SRX18491780 GSM6785855_r1 SRP351489 PRJNA790097 SRS15962538 GSM6785855 GSM6785855 RNA-Seq TRANSCRIPTOMIC cDNA For RNA-seq: RNA was isolated from tissue using TRIzol. Cell lysate was extracted with bromo-chloropropane and RNA was precipitated with 100% isopropanol supplemented with 10 μg of glycobluefor 10 min at room temperature and then pelleted at 16,000 x g for 30 min at 4°C. The RNA pellet was washed once with 75% ethanol and then resuspended in RNase-free water to a maximal concentration of 200 ng/μl. Genomic DNA contaminants were removed by Turbo DNase. Removal of Turbo DNase was performed by phenol:chloroform extraction and RNA was precipitated as described above and resuspended in RNase-free water and stored at -80°C. For Raphe RNA-seq: RNA was isolated from coronal sections of the Raphe (20 μm thick) obtainedfrom paraformaldehyde-fixed brain (described in more detail below, see paragraph “Preparation of Mouse Brain Tissue Sections”). After 3x 5 minutes washes of the slides with 1X PBS, a small portion of each section containing approximately the Raphe region was extracted. Then, the RNA was isolated using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE (Invitrogen) as instructed by the manufacturer. For in situ HiC was carried out according to Rao et al. 2014. For ChIP-seq: Cells were crosslinked with 1% formaldehyde for 10 minutes at room temperature. Formaldehyde was quenched by adding glycine to a final concentration of 0.125 M for 5 minutes at room temperature. Cells were then washed with 1X cold PBS with protein inhibitors twice and pelleted. Cell pellets were stored at -80°C till use. Cells were lysed in lysis buffer (50 mM Tris pH 7.5, 140 mM NaCl, 0.1% SDS, 0.1% sodium deoxycholate, 1% Triton X-100) for 10 minutes. Nuclei were spun for 10 minutes at 1000 x g and resuspended in the sonication buffer (10 mM Tris pH 7.5, 0.5% SDS) as 5million nuclei per 300 μl sonication buffer. Chromatin was sheared by Covaris (Peak power 105.0; Duty Factor 2.0; Cycle/Burst 200; Treatment 960 sec; Temperature 4-8°C). Following a spin at 13,000 x g for 10 minutes to remove debris, the sheared chromatin was diluted such that the final binding buffer concentration was 15 mM Tris-HCl pH 7.5, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS) and incubated for 2 hours with dynabeads G pre-equilibrated in the binding buffer for pre-clearing of the chromatin. Post-cleared chromatin was then incubated with the specific antibody overnight (1 μg of antibody was used per 5 million nuclei). The next day, dynabeads G were added to the chromatin-antibody mix for 2 hours. A total of four washes with 1X wash buffer (100 mM Tris pH 7.5, 500 mM LiCl, 1% NP-40, 1% sodium deoxycholate) and one wash with TE buffer (10 mM Tris pH 7.5, 1 mM EDTA) were performed. The elution was performed at65°C for 1 hour in the elution buffer (1% SDS, 250 mM NaCl, 2 mM DTT). All steps, with the exception of the elution, were performed at 4°C. All buffers, with the exception of the TE and elution buffer contained 1X protease inhibitors. The eluted chromatin was reverse-crosslinked overnight at 65°C and the DNA was purified with AMPure XP beads (Beckman Coulter). For RNA-Seq experiments, raw FASTQ files were aligned with either Tophat or STAR using hg19 or mm10 reference genomes. When libraries were made following the SMARTer Stranded Total RNA-Seq, the initial 4 base pairs of both paired reads were trimmed prior to alignment. For single cell RNA-seq, raw FASTQ files were analyzed using cellranger. For in situ Hi-C experiments, raw FASTQ files were analyzed using HiC-Pro and hic files were generated (Servant et al. 2015). NextSeq 500 SRX18491781 GSM6785856_r1 SRP351489 PRJNA790097 SRS15962539 GSM6785856 GSM6785856 RNA-Seq TRANSCRIPTOMIC cDNA For RNA-seq: RNA was isolated from tissue using TRIzol. Cell lysate was extracted with bromo-chloropropane and RNA was precipitated with 100% isopropanol supplemented with 10 μg of glycobluefor 10 min at room temperature and then pelleted at 16,000 x g for 30 min at 4°C. The RNA pellet was washed once with 75% ethanol and then resuspended in RNase-free water to a maximal concentration of 200 ng/μl. Genomic DNA contaminants were removed by Turbo DNase. Removal of Turbo DNase was performed by phenol:chloroform extraction and RNA was precipitated as described above and resuspended in RNase-free water and stored at -80°C. For Raphe RNA-seq: RNA was isolated from coronal sections of the Raphe (20 μm thick) obtainedfrom paraformaldehyde-fixed brain (described in more detail below, see paragraph “Preparation of Mouse Brain Tissue Sections”). After 3x 5 minutes washes of the slides with 1X PBS, a small portion of each section containing approximately the Raphe region was extracted. Then, the RNA was isolated using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE (Invitrogen) as instructed by the manufacturer. For in situ HiC was carried out according to Rao et al. 2014. For ChIP-seq: Cells were crosslinked with 1% formaldehyde for 10 minutes at room temperature. Formaldehyde was quenched by adding glycine to a final concentration of 0.125 M for 5 minutes at room temperature. Cells were then washed with 1X cold PBS with protein inhibitors twice and pelleted. Cell pellets were stored at -80°C till use. Cells were lysed in lysis buffer (50 mM Tris pH 7.5, 140 mM NaCl, 0.1% SDS, 0.1% sodium deoxycholate, 1% Triton X-100) for 10 minutes. Nuclei were spun for 10 minutes at 1000 x g and resuspended in the sonication buffer (10 mM Tris pH 7.5, 0.5% SDS) as 5million nuclei per 300 μl sonication buffer. Chromatin was sheared by Covaris (Peak power 105.0; Duty Factor 2.0; Cycle/Burst 200; Treatment 960 sec; Temperature 4-8°C). Following a spin at 13,000 x g for 10 minutes to remove debris, the sheared chromatin was diluted such that the final binding buffer concentration was 15 mM Tris-HCl pH 7.5, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS) and incubated for 2 hours with dynabeads G pre-equilibrated in the binding buffer for pre-clearing of the chromatin. Post-cleared chromatin was then incubated with the specific antibody overnight (1 μg of antibody was used per 5 million nuclei). The next day, dynabeads G were added to the chromatin-antibody mix for 2 hours. A total of four washes with 1X wash buffer (100 mM Tris pH 7.5, 500 mM LiCl, 1% NP-40, 1% sodium deoxycholate) and one wash with TE buffer (10 mM Tris pH 7.5, 1 mM EDTA) were performed. The elution was performed at65°C for 1 hour in the elution buffer (1% SDS, 250 mM NaCl, 2 mM DTT). All steps, with the exception of the elution, were performed at 4°C. All buffers, with the exception of the TE and elution buffer contained 1X protease inhibitors. The eluted chromatin was reverse-crosslinked overnight at 65°C and the DNA was purified with AMPure XP beads (Beckman Coulter). For RNA-Seq experiments, raw FASTQ files were aligned with either Tophat or STAR using hg19 or mm10 reference genomes. When libraries were made following the SMARTer Stranded Total RNA-Seq, the initial 4 base pairs of both paired reads were trimmed prior to alignment. For single cell RNA-seq, raw FASTQ files were analyzed using cellranger. For in situ Hi-C experiments, raw FASTQ files were analyzed using HiC-Pro and hic files were generated (Servant et al. 2015). NextSeq 500 SRX18491782 GSM6785858_r1 SRP351489 PRJNA790097 SRS15962540 GSM6785858 GSM6785858 RNA-Seq TRANSCRIPTOMIC cDNA For RNA-seq: RNA was isolated from tissue using TRIzol. Cell lysate was extracted with bromo-chloropropane and RNA was precipitated with 100% isopropanol supplemented with 10 μg of glycobluefor 10 min at room temperature and then pelleted at 16,000 x g for 30 min at 4°C. The RNA pellet was washed once with 75% ethanol and then resuspended in RNase-free water to a maximal concentration of 200 ng/μl. Genomic DNA contaminants were removed by Turbo DNase. Removal of Turbo DNase was performed by phenol:chloroform extraction and RNA was precipitated as described above and resuspended in RNase-free water and stored at -80°C. For Raphe RNA-seq: RNA was isolated from coronal sections of the Raphe (20 μm thick) obtainedfrom paraformaldehyde-fixed brain (described in more detail below, see paragraph “Preparation of Mouse Brain Tissue Sections”). After 3x 5 minutes washes of the slides with 1X PBS, a small portion of each section containing approximately the Raphe region was extracted. Then, the RNA was isolated using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE (Invitrogen) as instructed by the manufacturer. For in situ HiC was carried out according to Rao et al. 2014. For ChIP-seq: Cells were crosslinked with 1% formaldehyde for 10 minutes at room temperature. Formaldehyde was quenched by adding glycine to a final concentration of 0.125 M for 5 minutes at room temperature. Cells were then washed with 1X cold PBS with protein inhibitors twice and pelleted. Cell pellets were stored at -80°C till use. Cells were lysed in lysis buffer (50 mM Tris pH 7.5, 140 mM NaCl, 0.1% SDS, 0.1% sodium deoxycholate, 1% Triton X-100) for 10 minutes. Nuclei were spun for 10 minutes at 1000 x g and resuspended in the sonication buffer (10 mM Tris pH 7.5, 0.5% SDS) as 5million nuclei per 300 μl sonication buffer. Chromatin was sheared by Covaris (Peak power 105.0; Duty Factor 2.0; Cycle/Burst 200; Treatment 960 sec; Temperature 4-8°C). Following a spin at 13,000 x g for 10 minutes to remove debris, the sheared chromatin was diluted such that the final binding buffer concentration was 15 mM Tris-HCl pH 7.5, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS) and incubated for 2 hours with dynabeads G pre-equilibrated in the binding buffer for pre-clearing of the chromatin. Post-cleared chromatin was then incubated with the specific antibody overnight (1 μg of antibody was used per 5 million nuclei). The next day, dynabeads G were added to the chromatin-antibody mix for 2 hours. A total of four washes with 1X wash buffer (100 mM Tris pH 7.5, 500 mM LiCl, 1% NP-40, 1% sodium deoxycholate) and one wash with TE buffer (10 mM Tris pH 7.5, 1 mM EDTA) were performed. The elution was performed at65°C for 1 hour in the elution buffer (1% SDS, 250 mM NaCl, 2 mM DTT). All steps, with the exception of the elution, were performed at 4°C. All buffers, with the exception of the TE and elution buffer contained 1X protease inhibitors. The eluted chromatin was reverse-crosslinked overnight at 65°C and the DNA was purified with AMPure XP beads (Beckman Coulter). For RNA-Seq experiments, raw FASTQ files were aligned with either Tophat or STAR using hg19 or mm10 reference genomes. When libraries were made following the SMARTer Stranded Total RNA-Seq, the initial 4 base pairs of both paired reads were trimmed prior to alignment. For single cell RNA-seq, raw FASTQ files were analyzed using cellranger. For in situ Hi-C experiments, raw FASTQ files were analyzed using HiC-Pro and hic files were generated (Servant et al. 2015). NextSeq 500 SRX18491783 GSM6785859_r1 SRP351489 PRJNA790097 SRS15962541 GSM6785859 GSM6785859 RNA-Seq TRANSCRIPTOMIC cDNA For RNA-seq: RNA was isolated from tissue using TRIzol. Cell lysate was extracted with bromo-chloropropane and RNA was precipitated with 100% isopropanol supplemented with 10 μg of glycobluefor 10 min at room temperature and then pelleted at 16,000 x g for 30 min at 4°C. The RNA pellet was washed once with 75% ethanol and then resuspended in RNase-free water to a maximal concentration of 200 ng/μl. Genomic DNA contaminants were removed by Turbo DNase. Removal of Turbo DNase was performed by phenol:chloroform extraction and RNA was precipitated as described above and resuspended in RNase-free water and stored at -80°C. For Raphe RNA-seq: RNA was isolated from coronal sections of the Raphe (20 μm thick) obtainedfrom paraformaldehyde-fixed brain (described in more detail below, see paragraph “Preparation of Mouse Brain Tissue Sections”). After 3x 5 minutes washes of the slides with 1X PBS, a small portion of each section containing approximately the Raphe region was extracted. Then, the RNA was isolated using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE (Invitrogen) as instructed by the manufacturer. For in situ HiC was carried out according to Rao et al. 2014. For ChIP-seq: Cells were crosslinked with 1% formaldehyde for 10 minutes at room temperature. Formaldehyde was quenched by adding glycine to a final concentration of 0.125 M for 5 minutes at room temperature. Cells were then washed with 1X cold PBS with protein inhibitors twice and pelleted. Cell pellets were stored at -80°C till use. Cells were lysed in lysis buffer (50 mM Tris pH 7.5, 140 mM NaCl, 0.1% SDS, 0.1% sodium deoxycholate, 1% Triton X-100) for 10 minutes. Nuclei were spun for 10 minutes at 1000 x g and resuspended in the sonication buffer (10 mM Tris pH 7.5, 0.5% SDS) as 5million nuclei per 300 μl sonication buffer. Chromatin was sheared by Covaris (Peak power 105.0; Duty Factor 2.0; Cycle/Burst 200; Treatment 960 sec; Temperature 4-8°C). Following a spin at 13,000 x g for 10 minutes to remove debris, the sheared chromatin was diluted such that the final binding buffer concentration was 15 mM Tris-HCl pH 7.5, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS) and incubated for 2 hours with dynabeads G pre-equilibrated in the binding buffer for pre-clearing of the chromatin. Post-cleared chromatin was then incubated with the specific antibody overnight (1 μg of antibody was used per 5 million nuclei). The next day, dynabeads G were added to the chromatin-antibody mix for 2 hours. A total of four washes with 1X wash buffer (100 mM Tris pH 7.5, 500 mM LiCl, 1% NP-40, 1% sodium deoxycholate) and one wash with TE buffer (10 mM Tris pH 7.5, 1 mM EDTA) were performed. The elution was performed at65°C for 1 hour in the elution buffer (1% SDS, 250 mM NaCl, 2 mM DTT). All steps, with the exception of the elution, were performed at 4°C. All buffers, with the exception of the TE and elution buffer contained 1X protease inhibitors. The eluted chromatin was reverse-crosslinked overnight at 65°C and the DNA was purified with AMPure XP beads (Beckman Coulter). For RNA-Seq experiments, raw FASTQ files were aligned with either Tophat or STAR using hg19 or mm10 reference genomes. When libraries were made following the SMARTer Stranded Total RNA-Seq, the initial 4 base pairs of both paired reads were trimmed prior to alignment. For single cell RNA-seq, raw FASTQ files were analyzed using cellranger. For in situ Hi-C experiments, raw FASTQ files were analyzed using HiC-Pro and hic files were generated (Servant et al. 2015). NextSeq 500 SRX18491784 GSM6785861_r1 SRP351489 PRJNA790097 SRS15962542 GSM6785861 GSM6785861 RNA-Seq TRANSCRIPTOMIC cDNA For RNA-seq: RNA was isolated from tissue using TRIzol. Cell lysate was extracted with bromo-chloropropane and RNA was precipitated with 100% isopropanol supplemented with 10 μg of glycobluefor 10 min at room temperature and then pelleted at 16,000 x g for 30 min at 4°C. The RNA pellet was washed once with 75% ethanol and then resuspended in RNase-free water to a maximal concentration of 200 ng/μl. Genomic DNA contaminants were removed by Turbo DNase. Removal of Turbo DNase was performed by phenol:chloroform extraction and RNA was precipitated as described above and resuspended in RNase-free water and stored at -80°C. For Raphe RNA-seq: RNA was isolated from coronal sections of the Raphe (20 μm thick) obtainedfrom paraformaldehyde-fixed brain (described in more detail below, see paragraph “Preparation of Mouse Brain Tissue Sections”). After 3x 5 minutes washes of the slides with 1X PBS, a small portion of each section containing approximately the Raphe region was extracted. Then, the RNA was isolated using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE (Invitrogen) as instructed by the manufacturer. For in situ HiC was carried out according to Rao et al. 2014. For ChIP-seq: Cells were crosslinked with 1% formaldehyde for 10 minutes at room temperature. Formaldehyde was quenched by adding glycine to a final concentration of 0.125 M for 5 minutes at room temperature. Cells were then washed with 1X cold PBS with protein inhibitors twice and pelleted. Cell pellets were stored at -80°C till use. Cells were lysed in lysis buffer (50 mM Tris pH 7.5, 140 mM NaCl, 0.1% SDS, 0.1% sodium deoxycholate, 1% Triton X-100) for 10 minutes. Nuclei were spun for 10 minutes at 1000 x g and resuspended in the sonication buffer (10 mM Tris pH 7.5, 0.5% SDS) as 5million nuclei per 300 μl sonication buffer. Chromatin was sheared by Covaris (Peak power 105.0; Duty Factor 2.0; Cycle/Burst 200; Treatment 960 sec; Temperature 4-8°C). Following a spin at 13,000 x g for 10 minutes to remove debris, the sheared chromatin was diluted such that the final binding buffer concentration was 15 mM Tris-HCl pH 7.5, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS) and incubated for 2 hours with dynabeads G pre-equilibrated in the binding buffer for pre-clearing of the chromatin. Post-cleared chromatin was then incubated with the specific antibody overnight (1 μg of antibody was used per 5 million nuclei). The next day, dynabeads G were added to the chromatin-antibody mix for 2 hours. A total of four washes with 1X wash buffer (100 mM Tris pH 7.5, 500 mM LiCl, 1% NP-40, 1% sodium deoxycholate) and one wash with TE buffer (10 mM Tris pH 7.5, 1 mM EDTA) were performed. The elution was performed at65°C for 1 hour in the elution buffer (1% SDS, 250 mM NaCl, 2 mM DTT). All steps, with the exception of the elution, were performed at 4°C. All buffers, with the exception of the TE and elution buffer contained 1X protease inhibitors. The eluted chromatin was reverse-crosslinked overnight at 65°C and the DNA was purified with AMPure XP beads (Beckman Coulter). For RNA-Seq experiments, raw FASTQ files were aligned with either Tophat or STAR using hg19 or mm10 reference genomes. When libraries were made following the SMARTer Stranded Total RNA-Seq, the initial 4 base pairs of both paired reads were trimmed prior to alignment. For single cell RNA-seq, raw FASTQ files were analyzed using cellranger. For in situ Hi-C experiments, raw FASTQ files were analyzed using HiC-Pro and hic files were generated (Servant et al. 2015). NextSeq 500 SRX18491785 GSM6785862_r1 SRP351489 PRJNA790097 SRS15962543 GSM6785862 GSM6785862 RNA-Seq TRANSCRIPTOMIC cDNA For RNA-seq: RNA was isolated from tissue using TRIzol. Cell lysate was extracted with bromo-chloropropane and RNA was precipitated with 100% isopropanol supplemented with 10 μg of glycobluefor 10 min at room temperature and then pelleted at 16,000 x g for 30 min at 4°C. The RNA pellet was washed once with 75% ethanol and then resuspended in RNase-free water to a maximal concentration of 200 ng/μl. Genomic DNA contaminants were removed by Turbo DNase. Removal of Turbo DNase was performed by phenol:chloroform extraction and RNA was precipitated as described above and resuspended in RNase-free water and stored at -80°C. For Raphe RNA-seq: RNA was isolated from coronal sections of the Raphe (20 μm thick) obtainedfrom paraformaldehyde-fixed brain (described in more detail below, see paragraph “Preparation of Mouse Brain Tissue Sections”). After 3x 5 minutes washes of the slides with 1X PBS, a small portion of each section containing approximately the Raphe region was extracted. Then, the RNA was isolated using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE (Invitrogen) as instructed by the manufacturer. For in situ HiC was carried out according to Rao et al. 2014. For ChIP-seq: Cells were crosslinked with 1% formaldehyde for 10 minutes at room temperature. Formaldehyde was quenched by adding glycine to a final concentration of 0.125 M for 5 minutes at room temperature. Cells were then washed with 1X cold PBS with protein inhibitors twice and pelleted. Cell pellets were stored at -80°C till use. Cells were lysed in lysis buffer (50 mM Tris pH 7.5, 140 mM NaCl, 0.1% SDS, 0.1% sodium deoxycholate, 1% Triton X-100) for 10 minutes. Nuclei were spun for 10 minutes at 1000 x g and resuspended in the sonication buffer (10 mM Tris pH 7.5, 0.5% SDS) as 5million nuclei per 300 μl sonication buffer. Chromatin was sheared by Covaris (Peak power 105.0; Duty Factor 2.0; Cycle/Burst 200; Treatment 960 sec; Temperature 4-8°C). Following a spin at 13,000 x g for 10 minutes to remove debris, the sheared chromatin was diluted such that the final binding buffer concentration was 15 mM Tris-HCl pH 7.5, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS) and incubated for 2 hours with dynabeads G pre-equilibrated in the binding buffer for pre-clearing of the chromatin. Post-cleared chromatin was then incubated with the specific antibody overnight (1 μg of antibody was used per 5 million nuclei). The next day, dynabeads G were added to the chromatin-antibody mix for 2 hours. A total of four washes with 1X wash buffer (100 mM Tris pH 7.5, 500 mM LiCl, 1% NP-40, 1% sodium deoxycholate) and one wash with TE buffer (10 mM Tris pH 7.5, 1 mM EDTA) were performed. The elution was performed at65°C for 1 hour in the elution buffer (1% SDS, 250 mM NaCl, 2 mM DTT). All steps, with the exception of the elution, were performed at 4°C. All buffers, with the exception of the TE and elution buffer contained 1X protease inhibitors. The eluted chromatin was reverse-crosslinked overnight at 65°C and the DNA was purified with AMPure XP beads (Beckman Coulter). For RNA-Seq experiments, raw FASTQ files were aligned with either Tophat or STAR using hg19 or mm10 reference genomes. When libraries were made following the SMARTer Stranded Total RNA-Seq, the initial 4 base pairs of both paired reads were trimmed prior to alignment. For single cell RNA-seq, raw FASTQ files were analyzed using cellranger. For in situ Hi-C experiments, raw FASTQ files were analyzed using HiC-Pro and hic files were generated (Servant et al. 2015). NextSeq 500 SRX18491786 GSM6785864_r1 SRP351489 PRJNA790097 SRS15962544 GSM6785864 GSM6785864 RNA-Seq TRANSCRIPTOMIC cDNA For RNA-seq: RNA was isolated from tissue using TRIzol. Cell lysate was extracted with bromo-chloropropane and RNA was precipitated with 100% isopropanol supplemented with 10 μg of glycobluefor 10 min at room temperature and then pelleted at 16,000 x g for 30 min at 4°C. The RNA pellet was washed once with 75% ethanol and then resuspended in RNase-free water to a maximal concentration of 200 ng/μl. Genomic DNA contaminants were removed by Turbo DNase. Removal of Turbo DNase was performed by phenol:chloroform extraction and RNA was precipitated as described above and resuspended in RNase-free water and stored at -80°C. For Raphe RNA-seq: RNA was isolated from coronal sections of the Raphe (20 μm thick) obtainedfrom paraformaldehyde-fixed brain (described in more detail below, see paragraph “Preparation of Mouse Brain Tissue Sections”). After 3x 5 minutes washes of the slides with 1X PBS, a small portion of each section containing approximately the Raphe region was extracted. Then, the RNA was isolated using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE (Invitrogen) as instructed by the manufacturer. For in situ HiC was carried out according to Rao et al. 2014. For ChIP-seq: Cells were crosslinked with 1% formaldehyde for 10 minutes at room temperature. Formaldehyde was quenched by adding glycine to a final concentration of 0.125 M for 5 minutes at room temperature. Cells were then washed with 1X cold PBS with protein inhibitors twice and pelleted. Cell pellets were stored at -80°C till use. Cells were lysed in lysis buffer (50 mM Tris pH 7.5, 140 mM NaCl, 0.1% SDS, 0.1% sodium deoxycholate, 1% Triton X-100) for 10 minutes. Nuclei were spun for 10 minutes at 1000 x g and resuspended in the sonication buffer (10 mM Tris pH 7.5, 0.5% SDS) as 5million nuclei per 300 μl sonication buffer. Chromatin was sheared by Covaris (Peak power 105.0; Duty Factor 2.0; Cycle/Burst 200; Treatment 960 sec; Temperature 4-8°C). Following a spin at 13,000 x g for 10 minutes to remove debris, the sheared chromatin was diluted such that the final binding buffer concentration was 15 mM Tris-HCl pH 7.5, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS) and incubated for 2 hours with dynabeads G pre-equilibrated in the binding buffer for pre-clearing of the chromatin. Post-cleared chromatin was then incubated with the specific antibody overnight (1 μg of antibody was used per 5 million nuclei). The next day, dynabeads G were added to the chromatin-antibody mix for 2 hours. A total of four washes with 1X wash buffer (100 mM Tris pH 7.5, 500 mM LiCl, 1% NP-40, 1% sodium deoxycholate) and one wash with TE buffer (10 mM Tris pH 7.5, 1 mM EDTA) were performed. The elution was performed at65°C for 1 hour in the elution buffer (1% SDS, 250 mM NaCl, 2 mM DTT). All steps, with the exception of the elution, were performed at 4°C. All buffers, with the exception of the TE and elution buffer contained 1X protease inhibitors. The eluted chromatin was reverse-crosslinked overnight at 65°C and the DNA was purified with AMPure XP beads (Beckman Coulter). For RNA-Seq experiments, raw FASTQ files were aligned with either Tophat or STAR using hg19 or mm10 reference genomes. When libraries were made following the SMARTer Stranded Total RNA-Seq, the initial 4 base pairs of both paired reads were trimmed prior to alignment. For single cell RNA-seq, raw FASTQ files were analyzed using cellranger. For in situ Hi-C experiments, raw FASTQ files were analyzed using HiC-Pro and hic files were generated (Servant et al. 2015). NextSeq 500 SRX18491787 GSM6785865_r1 SRP351489 PRJNA790097 SRS15962545 GSM6785865 GSM6785865 RNA-Seq TRANSCRIPTOMIC cDNA For RNA-seq: RNA was isolated from tissue using TRIzol. Cell lysate was extracted with bromo-chloropropane and RNA was precipitated with 100% isopropanol supplemented with 10 μg of glycobluefor 10 min at room temperature and then pelleted at 16,000 x g for 30 min at 4°C. The RNA pellet was washed once with 75% ethanol and then resuspended in RNase-free water to a maximal concentration of 200 ng/μl. Genomic DNA contaminants were removed by Turbo DNase. Removal of Turbo DNase was performed by phenol:chloroform extraction and RNA was precipitated as described above and resuspended in RNase-free water and stored at -80°C. For Raphe RNA-seq: RNA was isolated from coronal sections of the Raphe (20 μm thick) obtainedfrom paraformaldehyde-fixed brain (described in more detail below, see paragraph “Preparation of Mouse Brain Tissue Sections”). After 3x 5 minutes washes of the slides with 1X PBS, a small portion of each section containing approximately the Raphe region was extracted. Then, the RNA was isolated using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE (Invitrogen) as instructed by the manufacturer. For in situ HiC was carried out according to Rao et al. 2014. For ChIP-seq: Cells were crosslinked with 1% formaldehyde for 10 minutes at room temperature. Formaldehyde was quenched by adding glycine to a final concentration of 0.125 M for 5 minutes at room temperature. Cells were then washed with 1X cold PBS with protein inhibitors twice and pelleted. Cell pellets were stored at -80°C till use. Cells were lysed in lysis buffer (50 mM Tris pH 7.5, 140 mM NaCl, 0.1% SDS, 0.1% sodium deoxycholate, 1% Triton X-100) for 10 minutes. Nuclei were spun for 10 minutes at 1000 x g and resuspended in the sonication buffer (10 mM Tris pH 7.5, 0.5% SDS) as 5million nuclei per 300 μl sonication buffer. Chromatin was sheared by Covaris (Peak power 105.0; Duty Factor 2.0; Cycle/Burst 200; Treatment 960 sec; Temperature 4-8°C). Following a spin at 13,000 x g for 10 minutes to remove debris, the sheared chromatin was diluted such that the final binding buffer concentration was 15 mM Tris-HCl pH 7.5, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS) and incubated for 2 hours with dynabeads G pre-equilibrated in the binding buffer for pre-clearing of the chromatin. Post-cleared chromatin was then incubated with the specific antibody overnight (1 μg of antibody was used per 5 million nuclei). The next day, dynabeads G were added to the chromatin-antibody mix for 2 hours. A total of four washes with 1X wash buffer (100 mM Tris pH 7.5, 500 mM LiCl, 1% NP-40, 1% sodium deoxycholate) and one wash with TE buffer (10 mM Tris pH 7.5, 1 mM EDTA) were performed. The elution was performed at65°C for 1 hour in the elution buffer (1% SDS, 250 mM NaCl, 2 mM DTT). All steps, with the exception of the elution, were performed at 4°C. All buffers, with the exception of the TE and elution buffer contained 1X protease inhibitors. The eluted chromatin was reverse-crosslinked overnight at 65°C and the DNA was purified with AMPure XP beads (Beckman Coulter). For RNA-Seq experiments, raw FASTQ files were aligned with either Tophat or STAR using hg19 or mm10 reference genomes. When libraries were made following the SMARTer Stranded Total RNA-Seq, the initial 4 base pairs of both paired reads were trimmed prior to alignment. For single cell RNA-seq, raw FASTQ files were analyzed using cellranger. For in situ Hi-C experiments, raw FASTQ files were analyzed using HiC-Pro and hic files were generated (Servant et al. 2015). NextSeq 500 SRX18491788 GSM6785867_r1 SRP351489 PRJNA790097 SRS15962546 GSM6785867 GSM6785867 RNA-Seq TRANSCRIPTOMIC cDNA For RNA-seq: RNA was isolated from tissue using TRIzol. Cell lysate was extracted with bromo-chloropropane and RNA was precipitated with 100% isopropanol supplemented with 10 μg of glycobluefor 10 min at room temperature and then pelleted at 16,000 x g for 30 min at 4°C. The RNA pellet was washed once with 75% ethanol and then resuspended in RNase-free water to a maximal concentration of 200 ng/μl. Genomic DNA contaminants were removed by Turbo DNase. Removal of Turbo DNase was performed by phenol:chloroform extraction and RNA was precipitated as described above and resuspended in RNase-free water and stored at -80°C. For Raphe RNA-seq: RNA was isolated from coronal sections of the Raphe (20 μm thick) obtainedfrom paraformaldehyde-fixed brain (described in more detail below, see paragraph “Preparation of Mouse Brain Tissue Sections”). After 3x 5 minutes washes of the slides with 1X PBS, a small portion of each section containing approximately the Raphe region was extracted. Then, the RNA was isolated using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE (Invitrogen) as instructed by the manufacturer. For in situ HiC was carried out according to Rao et al. 2014. For ChIP-seq: Cells were crosslinked with 1% formaldehyde for 10 minutes at room temperature. Formaldehyde was quenched by adding glycine to a final concentration of 0.125 M for 5 minutes at room temperature. Cells were then washed with 1X cold PBS with protein inhibitors twice and pelleted. Cell pellets were stored at -80°C till use. Cells were lysed in lysis buffer (50 mM Tris pH 7.5, 140 mM NaCl, 0.1% SDS, 0.1% sodium deoxycholate, 1% Triton X-100) for 10 minutes. Nuclei were spun for 10 minutes at 1000 x g and resuspended in the sonication buffer (10 mM Tris pH 7.5, 0.5% SDS) as 5million nuclei per 300 μl sonication buffer. Chromatin was sheared by Covaris (Peak power 105.0; Duty Factor 2.0; Cycle/Burst 200; Treatment 960 sec; Temperature 4-8°C). Following a spin at 13,000 x g for 10 minutes to remove debris, the sheared chromatin was diluted such that the final binding buffer concentration was 15 mM Tris-HCl pH 7.5, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS) and incubated for 2 hours with dynabeads G pre-equilibrated in the binding buffer for pre-clearing of the chromatin. Post-cleared chromatin was then incubated with the specific antibody overnight (1 μg of antibody was used per 5 million nuclei). The next day, dynabeads G were added to the chromatin-antibody mix for 2 hours. A total of four washes with 1X wash buffer (100 mM Tris pH 7.5, 500 mM LiCl, 1% NP-40, 1% sodium deoxycholate) and one wash with TE buffer (10 mM Tris pH 7.5, 1 mM EDTA) were performed. The elution was performed at65°C for 1 hour in the elution buffer (1% SDS, 250 mM NaCl, 2 mM DTT). All steps, with the exception of the elution, were performed at 4°C. All buffers, with the exception of the TE and elution buffer contained 1X protease inhibitors. The eluted chromatin was reverse-crosslinked overnight at 65°C and the DNA was purified with AMPure XP beads (Beckman Coulter). For RNA-Seq experiments, raw FASTQ files were aligned with either Tophat or STAR using hg19 or mm10 reference genomes. When libraries were made following the SMARTer Stranded Total RNA-Seq, the initial 4 base pairs of both paired reads were trimmed prior to alignment. For single cell RNA-seq, raw FASTQ files were analyzed using cellranger. For in situ Hi-C experiments, raw FASTQ files were analyzed using HiC-Pro and hic files were generated (Servant et al. 2015). NextSeq 500 SRX18491789 GSM6785868_r1 SRP351489 PRJNA790097 SRS15962547 GSM6785868 GSM6785868 RNA-Seq TRANSCRIPTOMIC cDNA For RNA-seq: RNA was isolated from tissue using TRIzol. Cell lysate was extracted with bromo-chloropropane and RNA was precipitated with 100% isopropanol supplemented with 10 μg of glycobluefor 10 min at room temperature and then pelleted at 16,000 x g for 30 min at 4°C. The RNA pellet was washed once with 75% ethanol and then resuspended in RNase-free water to a maximal concentration of 200 ng/μl. Genomic DNA contaminants were removed by Turbo DNase. Removal of Turbo DNase was performed by phenol:chloroform extraction and RNA was precipitated as described above and resuspended in RNase-free water and stored at -80°C. For Raphe RNA-seq: RNA was isolated from coronal sections of the Raphe (20 μm thick) obtainedfrom paraformaldehyde-fixed brain (described in more detail below, see paragraph “Preparation of Mouse Brain Tissue Sections”). After 3x 5 minutes washes of the slides with 1X PBS, a small portion of each section containing approximately the Raphe region was extracted. Then, the RNA was isolated using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE (Invitrogen) as instructed by the manufacturer. For in situ HiC was carried out according to Rao et al. 2014. For ChIP-seq: Cells were crosslinked with 1% formaldehyde for 10 minutes at room temperature. Formaldehyde was quenched by adding glycine to a final concentration of 0.125 M for 5 minutes at room temperature. Cells were then washed with 1X cold PBS with protein inhibitors twice and pelleted. Cell pellets were stored at -80°C till use. Cells were lysed in lysis buffer (50 mM Tris pH 7.5, 140 mM NaCl, 0.1% SDS, 0.1% sodium deoxycholate, 1% Triton X-100) for 10 minutes. Nuclei were spun for 10 minutes at 1000 x g and resuspended in the sonication buffer (10 mM Tris pH 7.5, 0.5% SDS) as 5million nuclei per 300 μl sonication buffer. Chromatin was sheared by Covaris (Peak power 105.0; Duty Factor 2.0; Cycle/Burst 200; Treatment 960 sec; Temperature 4-8°C). Following a spin at 13,000 x g for 10 minutes to remove debris, the sheared chromatin was diluted such that the final binding buffer concentration was 15 mM Tris-HCl pH 7.5, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS) and incubated for 2 hours with dynabeads G pre-equilibrated in the binding buffer for pre-clearing of the chromatin. Post-cleared chromatin was then incubated with the specific antibody overnight (1 μg of antibody was used per 5 million nuclei). The next day, dynabeads G were added to the chromatin-antibody mix for 2 hours. A total of four washes with 1X wash buffer (100 mM Tris pH 7.5, 500 mM LiCl, 1% NP-40, 1% sodium deoxycholate) and one wash with TE buffer (10 mM Tris pH 7.5, 1 mM EDTA) were performed. The elution was performed at65°C for 1 hour in the elution buffer (1% SDS, 250 mM NaCl, 2 mM DTT). All steps, with the exception of the elution, were performed at 4°C. All buffers, with the exception of the TE and elution buffer contained 1X protease inhibitors. The eluted chromatin was reverse-crosslinked overnight at 65°C and the DNA was purified with AMPure XP beads (Beckman Coulter). For RNA-Seq experiments, raw FASTQ files were aligned with either Tophat or STAR using hg19 or mm10 reference genomes. When libraries were made following the SMARTer Stranded Total RNA-Seq, the initial 4 base pairs of both paired reads were trimmed prior to alignment. For single cell RNA-seq, raw FASTQ files were analyzed using cellranger. For in situ Hi-C experiments, raw FASTQ files were analyzed using HiC-Pro and hic files were generated (Servant et al. 2015). NextSeq 500 SRX18491790 GSM6785870_r1 SRP351489 PRJNA790097 SRS15962548 GSM6785870 GSM6785870 RNA-Seq TRANSCRIPTOMIC cDNA For RNA-seq: RNA was isolated from tissue using TRIzol. Cell lysate was extracted with bromo-chloropropane and RNA was precipitated with 100% isopropanol supplemented with 10 μg of glycobluefor 10 min at room temperature and then pelleted at 16,000 x g for 30 min at 4°C. The RNA pellet was washed once with 75% ethanol and then resuspended in RNase-free water to a maximal concentration of 200 ng/μl. Genomic DNA contaminants were removed by Turbo DNase. Removal of Turbo DNase was performed by phenol:chloroform extraction and RNA was precipitated as described above and resuspended in RNase-free water and stored at -80°C. For Raphe RNA-seq: RNA was isolated from coronal sections of the Raphe (20 μm thick) obtainedfrom paraformaldehyde-fixed brain (described in more detail below, see paragraph “Preparation of Mouse Brain Tissue Sections”). After 3x 5 minutes washes of the slides with 1X PBS, a small portion of each section containing approximately the Raphe region was extracted. Then, the RNA was isolated using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE (Invitrogen) as instructed by the manufacturer. For in situ HiC was carried out according to Rao et al. 2014. For ChIP-seq: Cells were crosslinked with 1% formaldehyde for 10 minutes at room temperature. Formaldehyde was quenched by adding glycine to a final concentration of 0.125 M for 5 minutes at room temperature. Cells were then washed with 1X cold PBS with protein inhibitors twice and pelleted. Cell pellets were stored at -80°C till use. Cells were lysed in lysis buffer (50 mM Tris pH 7.5, 140 mM NaCl, 0.1% SDS, 0.1% sodium deoxycholate, 1% Triton X-100) for 10 minutes. Nuclei were spun for 10 minutes at 1000 x g and resuspended in the sonication buffer (10 mM Tris pH 7.5, 0.5% SDS) as 5million nuclei per 300 μl sonication buffer. Chromatin was sheared by Covaris (Peak power 105.0; Duty Factor 2.0; Cycle/Burst 200; Treatment 960 sec; Temperature 4-8°C). Following a spin at 13,000 x g for 10 minutes to remove debris, the sheared chromatin was diluted such that the final binding buffer concentration was 15 mM Tris-HCl pH 7.5, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS) and incubated for 2 hours with dynabeads G pre-equilibrated in the binding buffer for pre-clearing of the chromatin. Post-cleared chromatin was then incubated with the specific antibody overnight (1 μg of antibody was used per 5 million nuclei). The next day, dynabeads G were added to the chromatin-antibody mix for 2 hours. A total of four washes with 1X wash buffer (100 mM Tris pH 7.5, 500 mM LiCl, 1% NP-40, 1% sodium deoxycholate) and one wash with TE buffer (10 mM Tris pH 7.5, 1 mM EDTA) were performed. The elution was performed at65°C for 1 hour in the elution buffer (1% SDS, 250 mM NaCl, 2 mM DTT). All steps, with the exception of the elution, were performed at 4°C. All buffers, with the exception of the TE and elution buffer contained 1X protease inhibitors. The eluted chromatin was reverse-crosslinked overnight at 65°C and the DNA was purified with AMPure XP beads (Beckman Coulter). For RNA-Seq experiments, raw FASTQ files were aligned with either Tophat or STAR using hg19 or mm10 reference genomes. When libraries were made following the SMARTer Stranded Total RNA-Seq, the initial 4 base pairs of both paired reads were trimmed prior to alignment. For single cell RNA-seq, raw FASTQ files were analyzed using cellranger. For in situ Hi-C experiments, raw FASTQ files were analyzed using HiC-Pro and hic files were generated (Servant et al. 2015). NextSeq 500 SRX18491791 GSM6785871_r1 SRP351489 PRJNA790097 SRS15962549 GSM6785871 GSM6785871 RNA-Seq TRANSCRIPTOMIC cDNA For RNA-seq: RNA was isolated from tissue using TRIzol. Cell lysate was extracted with bromo-chloropropane and RNA was precipitated with 100% isopropanol supplemented with 10 μg of glycobluefor 10 min at room temperature and then pelleted at 16,000 x g for 30 min at 4°C. The RNA pellet was washed once with 75% ethanol and then resuspended in RNase-free water to a maximal concentration of 200 ng/μl. Genomic DNA contaminants were removed by Turbo DNase. Removal of Turbo DNase was performed by phenol:chloroform extraction and RNA was precipitated as described above and resuspended in RNase-free water and stored at -80°C. For Raphe RNA-seq: RNA was isolated from coronal sections of the Raphe (20 μm thick) obtainedfrom paraformaldehyde-fixed brain (described in more detail below, see paragraph “Preparation of Mouse Brain Tissue Sections”). After 3x 5 minutes washes of the slides with 1X PBS, a small portion of each section containing approximately the Raphe region was extracted. Then, the RNA was isolated using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE (Invitrogen) as instructed by the manufacturer. For in situ HiC was carried out according to Rao et al. 2014. For ChIP-seq: Cells were crosslinked with 1% formaldehyde for 10 minutes at room temperature. Formaldehyde was quenched by adding glycine to a final concentration of 0.125 M for 5 minutes at room temperature. Cells were then washed with 1X cold PBS with protein inhibitors twice and pelleted. Cell pellets were stored at -80°C till use. Cells were lysed in lysis buffer (50 mM Tris pH 7.5, 140 mM NaCl, 0.1% SDS, 0.1% sodium deoxycholate, 1% Triton X-100) for 10 minutes. Nuclei were spun for 10 minutes at 1000 x g and resuspended in the sonication buffer (10 mM Tris pH 7.5, 0.5% SDS) as 5million nuclei per 300 μl sonication buffer. Chromatin was sheared by Covaris (Peak power 105.0; Duty Factor 2.0; Cycle/Burst 200; Treatment 960 sec; Temperature 4-8°C). Following a spin at 13,000 x g for 10 minutes to remove debris, the sheared chromatin was diluted such that the final binding buffer concentration was 15 mM Tris-HCl pH 7.5, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS) and incubated for 2 hours with dynabeads G pre-equilibrated in the binding buffer for pre-clearing of the chromatin. Post-cleared chromatin was then incubated with the specific antibody overnight (1 μg of antibody was used per 5 million nuclei). The next day, dynabeads G were added to the chromatin-antibody mix for 2 hours. A total of four washes with 1X wash buffer (100 mM Tris pH 7.5, 500 mM LiCl, 1% NP-40, 1% sodium deoxycholate) and one wash with TE buffer (10 mM Tris pH 7.5, 1 mM EDTA) were performed. The elution was performed at65°C for 1 hour in the elution buffer (1% SDS, 250 mM NaCl, 2 mM DTT). All steps, with the exception of the elution, were performed at 4°C. All buffers, with the exception of the TE and elution buffer contained 1X protease inhibitors. The eluted chromatin was reverse-crosslinked overnight at 65°C and the DNA was purified with AMPure XP beads (Beckman Coulter). For RNA-Seq experiments, raw FASTQ files were aligned with either Tophat or STAR using hg19 or mm10 reference genomes. When libraries were made following the SMARTer Stranded Total RNA-Seq, the initial 4 base pairs of both paired reads were trimmed prior to alignment. For single cell RNA-seq, raw FASTQ files were analyzed using cellranger. For in situ Hi-C experiments, raw FASTQ files were analyzed using HiC-Pro and hic files were generated (Servant et al. 2015). NextSeq 500 SRX18491792 GSM6785873_r1 SRP351489 PRJNA790097 SRS15962550 GSM6785873 GSM6785873 RNA-Seq TRANSCRIPTOMIC cDNA For RNA-seq: RNA was isolated from tissue using TRIzol. Cell lysate was extracted with bromo-chloropropane and RNA was precipitated with 100% isopropanol supplemented with 10 μg of glycobluefor 10 min at room temperature and then pelleted at 16,000 x g for 30 min at 4°C. The RNA pellet was washed once with 75% ethanol and then resuspended in RNase-free water to a maximal concentration of 200 ng/μl. Genomic DNA contaminants were removed by Turbo DNase. Removal of Turbo DNase was performed by phenol:chloroform extraction and RNA was precipitated as described above and resuspended in RNase-free water and stored at -80°C. For Raphe RNA-seq: RNA was isolated from coronal sections of the Raphe (20 μm thick) obtainedfrom paraformaldehyde-fixed brain (described in more detail below, see paragraph “Preparation of Mouse Brain Tissue Sections”). After 3x 5 minutes washes of the slides with 1X PBS, a small portion of each section containing approximately the Raphe region was extracted. Then, the RNA was isolated using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE (Invitrogen) as instructed by the manufacturer. For in situ HiC was carried out according to Rao et al. 2014. For ChIP-seq: Cells were crosslinked with 1% formaldehyde for 10 minutes at room temperature. Formaldehyde was quenched by adding glycine to a final concentration of 0.125 M for 5 minutes at room temperature. Cells were then washed with 1X cold PBS with protein inhibitors twice and pelleted. Cell pellets were stored at -80°C till use. Cells were lysed in lysis buffer (50 mM Tris pH 7.5, 140 mM NaCl, 0.1% SDS, 0.1% sodium deoxycholate, 1% Triton X-100) for 10 minutes. Nuclei were spun for 10 minutes at 1000 x g and resuspended in the sonication buffer (10 mM Tris pH 7.5, 0.5% SDS) as 5million nuclei per 300 μl sonication buffer. Chromatin was sheared by Covaris (Peak power 105.0; Duty Factor 2.0; Cycle/Burst 200; Treatment 960 sec; Temperature 4-8°C). Following a spin at 13,000 x g for 10 minutes to remove debris, the sheared chromatin was diluted such that the final binding buffer concentration was 15 mM Tris-HCl pH 7.5, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS) and incubated for 2 hours with dynabeads G pre-equilibrated in the binding buffer for pre-clearing of the chromatin. Post-cleared chromatin was then incubated with the specific antibody overnight (1 μg of antibody was used per 5 million nuclei). The next day, dynabeads G were added to the chromatin-antibody mix for 2 hours. A total of four washes with 1X wash buffer (100 mM Tris pH 7.5, 500 mM LiCl, 1% NP-40, 1% sodium deoxycholate) and one wash with TE buffer (10 mM Tris pH 7.5, 1 mM EDTA) were performed. The elution was performed at65°C for 1 hour in the elution buffer (1% SDS, 250 mM NaCl, 2 mM DTT). All steps, with the exception of the elution, were performed at 4°C. All buffers, with the exception of the TE and elution buffer contained 1X protease inhibitors. The eluted chromatin was reverse-crosslinked overnight at 65°C and the DNA was purified with AMPure XP beads (Beckman Coulter). For RNA-Seq experiments, raw FASTQ files were aligned with either Tophat or STAR using hg19 or mm10 reference genomes. When libraries were made following the SMARTer Stranded Total RNA-Seq, the initial 4 base pairs of both paired reads were trimmed prior to alignment. For single cell RNA-seq, raw FASTQ files were analyzed using cellranger. For in situ Hi-C experiments, raw FASTQ files were analyzed using HiC-Pro and hic files were generated (Servant et al. 2015). NextSeq 500 SRX18491793 GSM6785874_r1 SRP351489 PRJNA790097 SRS15962552 GSM6785874 GSM6785874 RNA-Seq TRANSCRIPTOMIC cDNA For RNA-seq: RNA was isolated from tissue using TRIzol. Cell lysate was extracted with bromo-chloropropane and RNA was precipitated with 100% isopropanol supplemented with 10 μg of glycobluefor 10 min at room temperature and then pelleted at 16,000 x g for 30 min at 4°C. The RNA pellet was washed once with 75% ethanol and then resuspended in RNase-free water to a maximal concentration of 200 ng/μl. Genomic DNA contaminants were removed by Turbo DNase. Removal of Turbo DNase was performed by phenol:chloroform extraction and RNA was precipitated as described above and resuspended in RNase-free water and stored at -80°C. For Raphe RNA-seq: RNA was isolated from coronal sections of the Raphe (20 μm thick) obtainedfrom paraformaldehyde-fixed brain (described in more detail below, see paragraph “Preparation of Mouse Brain Tissue Sections”). After 3x 5 minutes washes of the slides with 1X PBS, a small portion of each section containing approximately the Raphe region was extracted. Then, the RNA was isolated using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE (Invitrogen) as instructed by the manufacturer. For in situ HiC was carried out according to Rao et al. 2014. For ChIP-seq: Cells were crosslinked with 1% formaldehyde for 10 minutes at room temperature. Formaldehyde was quenched by adding glycine to a final concentration of 0.125 M for 5 minutes at room temperature. Cells were then washed with 1X cold PBS with protein inhibitors twice and pelleted. Cell pellets were stored at -80°C till use. Cells were lysed in lysis buffer (50 mM Tris pH 7.5, 140 mM NaCl, 0.1% SDS, 0.1% sodium deoxycholate, 1% Triton X-100) for 10 minutes. Nuclei were spun for 10 minutes at 1000 x g and resuspended in the sonication buffer (10 mM Tris pH 7.5, 0.5% SDS) as 5million nuclei per 300 μl sonication buffer. Chromatin was sheared by Covaris (Peak power 105.0; Duty Factor 2.0; Cycle/Burst 200; Treatment 960 sec; Temperature 4-8°C). Following a spin at 13,000 x g for 10 minutes to remove debris, the sheared chromatin was diluted such that the final binding buffer concentration was 15 mM Tris-HCl pH 7.5, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS) and incubated for 2 hours with dynabeads G pre-equilibrated in the binding buffer for pre-clearing of the chromatin. Post-cleared chromatin was then incubated with the specific antibody overnight (1 μg of antibody was used per 5 million nuclei). The next day, dynabeads G were added to the chromatin-antibody mix for 2 hours. A total of four washes with 1X wash buffer (100 mM Tris pH 7.5, 500 mM LiCl, 1% NP-40, 1% sodium deoxycholate) and one wash with TE buffer (10 mM Tris pH 7.5, 1 mM EDTA) were performed. The elution was performed at65°C for 1 hour in the elution buffer (1% SDS, 250 mM NaCl, 2 mM DTT). All steps, with the exception of the elution, were performed at 4°C. All buffers, with the exception of the TE and elution buffer contained 1X protease inhibitors. The eluted chromatin was reverse-crosslinked overnight at 65°C and the DNA was purified with AMPure XP beads (Beckman Coulter). For RNA-Seq experiments, raw FASTQ files were aligned with either Tophat or STAR using hg19 or mm10 reference genomes. When libraries were made following the SMARTer Stranded Total RNA-Seq, the initial 4 base pairs of both paired reads were trimmed prior to alignment. For single cell RNA-seq, raw FASTQ files were analyzed using cellranger. For in situ Hi-C experiments, raw FASTQ files were analyzed using HiC-Pro and hic files were generated (Servant et al. 2015). NextSeq 500 SRX18491794 GSM6785876_r1 SRP351489 PRJNA790097 SRS15962551 GSM6785876 GSM6785876 RNA-Seq TRANSCRIPTOMIC cDNA For RNA-seq: RNA was isolated from tissue using TRIzol. Cell lysate was extracted with bromo-chloropropane and RNA was precipitated with 100% isopropanol supplemented with 10 μg of glycobluefor 10 min at room temperature and then pelleted at 16,000 x g for 30 min at 4°C. The RNA pellet was washed once with 75% ethanol and then resuspended in RNase-free water to a maximal concentration of 200 ng/μl. Genomic DNA contaminants were removed by Turbo DNase. Removal of Turbo DNase was performed by phenol:chloroform extraction and RNA was precipitated as described above and resuspended in RNase-free water and stored at -80°C. For Raphe RNA-seq: RNA was isolated from coronal sections of the Raphe (20 μm thick) obtainedfrom paraformaldehyde-fixed brain (described in more detail below, see paragraph “Preparation of Mouse Brain Tissue Sections”). After 3x 5 minutes washes of the slides with 1X PBS, a small portion of each section containing approximately the Raphe region was extracted. Then, the RNA was isolated using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE (Invitrogen) as instructed by the manufacturer. For in situ HiC was carried out according to Rao et al. 2014. For ChIP-seq: Cells were crosslinked with 1% formaldehyde for 10 minutes at room temperature. Formaldehyde was quenched by adding glycine to a final concentration of 0.125 M for 5 minutes at room temperature. Cells were then washed with 1X cold PBS with protein inhibitors twice and pelleted. Cell pellets were stored at -80°C till use. Cells were lysed in lysis buffer (50 mM Tris pH 7.5, 140 mM NaCl, 0.1% SDS, 0.1% sodium deoxycholate, 1% Triton X-100) for 10 minutes. Nuclei were spun for 10 minutes at 1000 x g and resuspended in the sonication buffer (10 mM Tris pH 7.5, 0.5% SDS) as 5million nuclei per 300 μl sonication buffer. Chromatin was sheared by Covaris (Peak power 105.0; Duty Factor 2.0; Cycle/Burst 200; Treatment 960 sec; Temperature 4-8°C). Following a spin at 13,000 x g for 10 minutes to remove debris, the sheared chromatin was diluted such that the final binding buffer concentration was 15 mM Tris-HCl pH 7.5, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS) and incubated for 2 hours with dynabeads G pre-equilibrated in the binding buffer for pre-clearing of the chromatin. Post-cleared chromatin was then incubated with the specific antibody overnight (1 μg of antibody was used per 5 million nuclei). The next day, dynabeads G were added to the chromatin-antibody mix for 2 hours. A total of four washes with 1X wash buffer (100 mM Tris pH 7.5, 500 mM LiCl, 1% NP-40, 1% sodium deoxycholate) and one wash with TE buffer (10 mM Tris pH 7.5, 1 mM EDTA) were performed. The elution was performed at65°C for 1 hour in the elution buffer (1% SDS, 250 mM NaCl, 2 mM DTT). All steps, with the exception of the elution, were performed at 4°C. All buffers, with the exception of the TE and elution buffer contained 1X protease inhibitors. The eluted chromatin was reverse-crosslinked overnight at 65°C and the DNA was purified with AMPure XP beads (Beckman Coulter). For RNA-Seq experiments, raw FASTQ files were aligned with either Tophat or STAR using hg19 or mm10 reference genomes. When libraries were made following the SMARTer Stranded Total RNA-Seq, the initial 4 base pairs of both paired reads were trimmed prior to alignment. For single cell RNA-seq, raw FASTQ files were analyzed using cellranger. For in situ Hi-C experiments, raw FASTQ files were analyzed using HiC-Pro and hic files were generated (Servant et al. 2015). NextSeq 500 SRX18491795 GSM6785877_r1 SRP351489 PRJNA790097 SRS15962553 GSM6785877 GSM6785877 Hi-C GENOMIC other For RNA-seq: RNA was isolated from tissue using TRIzol. Cell lysate was extracted with bromo-chloropropane and RNA was precipitated with 100% isopropanol supplemented with 10 μg of glycobluefor 10 min at room temperature and then pelleted at 16,000 x g for 30 min at 4°C. The RNA pellet was washed once with 75% ethanol and then resuspended in RNase-free water to a maximal concentration of 200 ng/μl. Genomic DNA contaminants were removed by Turbo DNase. Removal of Turbo DNase was performed by phenol:chloroform extraction and RNA was precipitated as described above and resuspended in RNase-free water and stored at -80°C. For Raphe RNA-seq: RNA was isolated from coronal sections of the Raphe (20 μm thick) obtainedfrom paraformaldehyde-fixed brain (described in more detail below, see paragraph “Preparation of Mouse Brain Tissue Sections”). After 3x 5 minutes washes of the slides with 1X PBS, a small portion of each section containing approximately the Raphe region was extracted. Then, the RNA was isolated using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE (Invitrogen) as instructed by the manufacturer. For in situ HiC was carried out according to Rao et al. 2014. For ChIP-seq: Cells were crosslinked with 1% formaldehyde for 10 minutes at room temperature. Formaldehyde was quenched by adding glycine to a final concentration of 0.125 M for 5 minutes at room temperature. Cells were then washed with 1X cold PBS with protein inhibitors twice and pelleted. Cell pellets were stored at -80°C till use. Cells were lysed in lysis buffer (50 mM Tris pH 7.5, 140 mM NaCl, 0.1% SDS, 0.1% sodium deoxycholate, 1% Triton X-100) for 10 minutes. Nuclei were spun for 10 minutes at 1000 x g and resuspended in the sonication buffer (10 mM Tris pH 7.5, 0.5% SDS) as 5million nuclei per 300 μl sonication buffer. Chromatin was sheared by Covaris (Peak power 105.0; Duty Factor 2.0; Cycle/Burst 200; Treatment 960 sec; Temperature 4-8°C). Following a spin at 13,000 x g for 10 minutes to remove debris, the sheared chromatin was diluted such that the final binding buffer concentration was 15 mM Tris-HCl pH 7.5, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS) and incubated for 2 hours with dynabeads G pre-equilibrated in the binding buffer for pre-clearing of the chromatin. Post-cleared chromatin was then incubated with the specific antibody overnight (1 μg of antibody was used per 5 million nuclei). The next day, dynabeads G were added to the chromatin-antibody mix for 2 hours. A total of four washes with 1X wash buffer (100 mM Tris pH 7.5, 500 mM LiCl, 1% NP-40, 1% sodium deoxycholate) and one wash with TE buffer (10 mM Tris pH 7.5, 1 mM EDTA) were performed. The elution was performed at65°C for 1 hour in the elution buffer (1% SDS, 250 mM NaCl, 2 mM DTT). All steps, with the exception of the elution, were performed at 4°C. All buffers, with the exception of the TE and elution buffer contained 1X protease inhibitors. The eluted chromatin was reverse-crosslinked overnight at 65°C and the DNA was purified with AMPure XP beads (Beckman Coulter). For RNA-Seq experiments, raw FASTQ files were aligned with either Tophat or STAR using hg19 or mm10 reference genomes. When libraries were made following the SMARTer Stranded Total RNA-Seq, the initial 4 base pairs of both paired reads were trimmed prior to alignment. For single cell RNA-seq, raw FASTQ files were analyzed using cellranger. For in situ Hi-C experiments, raw FASTQ files were analyzed using HiC-Pro and hic files were generated (Servant et al. 2015). NextSeq 2000 SRX18491796 GSM6785879_r1 SRP351489 PRJNA790097 SRS15962554 GSM6785879 GSM6785879 Hi-C GENOMIC other For RNA-seq: RNA was isolated from tissue using TRIzol. Cell lysate was extracted with bromo-chloropropane and RNA was precipitated with 100% isopropanol supplemented with 10 μg of glycobluefor 10 min at room temperature and then pelleted at 16,000 x g for 30 min at 4°C. The RNA pellet was washed once with 75% ethanol and then resuspended in RNase-free water to a maximal concentration of 200 ng/μl. Genomic DNA contaminants were removed by Turbo DNase. Removal of Turbo DNase was performed by phenol:chloroform extraction and RNA was precipitated as described above and resuspended in RNase-free water and stored at -80°C. For Raphe RNA-seq: RNA was isolated from coronal sections of the Raphe (20 μm thick) obtainedfrom paraformaldehyde-fixed brain (described in more detail below, see paragraph “Preparation of Mouse Brain Tissue Sections”). After 3x 5 minutes washes of the slides with 1X PBS, a small portion of each section containing approximately the Raphe region was extracted. Then, the RNA was isolated using RecoverAll™ Total Nucleic Acid Isolation Kit for FFPE (Invitrogen) as instructed by the manufacturer. For in situ HiC was carried out according to Rao et al. 2014. For ChIP-seq: Cells were crosslinked with 1% formaldehyde for 10 minutes at room temperature. Formaldehyde was quenched by adding glycine to a final concentration of 0.125 M for 5 minutes at room temperature. Cells were then washed with 1X cold PBS with protein inhibitors twice and pelleted. Cell pellets were stored at -80°C till use. Cells were lysed in lysis buffer (50 mM Tris pH 7.5, 140 mM NaCl, 0.1% SDS, 0.1% sodium deoxycholate, 1% Triton X-100) for 10 minutes. Nuclei were spun for 10 minutes at 1000 x g and resuspended in the sonication buffer (10 mM Tris pH 7.5, 0.5% SDS) as 5million nuclei per 300 μl sonication buffer. Chromatin was sheared by Covaris (Peak power 105.0; Duty Factor 2.0; Cycle/Burst 200; Treatment 960 sec; Temperature 4-8°C). Following a spin at 13,000 x g for 10 minutes to remove debris, the sheared chromatin was diluted such that the final binding buffer concentration was 15 mM Tris-HCl pH 7.5, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS) and incubated for 2 hours with dynabeads G pre-equilibrated in the binding buffer for pre-clearing of the chromatin. Post-cleared chromatin was then incubated with the specific antibody overnight (1 μg of antibody was used per 5 million nuclei). The next day, dynabeads G were added to the chromatin-antibody mix for 2 hours. A total of four washes with 1X wash buffer (100 mM Tris pH 7.5, 500 mM LiCl, 1% NP-40, 1% sodium deoxycholate) and one wash with TE buffer (10 mM Tris pH 7.5, 1 mM EDTA) were performed. The elution was performed at65°C for 1 hour in the elution buffer (1% SDS, 250 mM NaCl, 2 mM DTT). All steps, with the exception of the elution, were performed at 4°C. All buffers, with the exception of the TE and elution buffer contained 1X protease inhibitors. The eluted chromatin was reverse-crosslinked overnight at 65°C and the DNA was purified with AMPure XP beads (Beckman Coulter). For RNA-Seq experiments, raw FASTQ files were aligned with either Tophat or STAR using hg19 or mm10 reference genomes. When libraries were made following the SMARTer Stranded Total RNA-Seq, the initial 4 base pairs of both paired reads were trimmed prior to alignment. For single cell RNA-seq, raw FASTQ files were analyzed using cellranger. For in situ Hi-C experiments, raw FASTQ files were analyzed using HiC-Pro and hic files were generated (Servant et al. 2015). NextSeq 2000