ERP128343 PRJEB44308 ena-STUDY-MPI FOR MOLECULAR GENETICS-14-04-2021-20:51:04:655-897 MYNRL15 in myeloid leukemia The noncoding genome presents a largely untapped source of new biological insights, including thousands of long noncoding RNA (lncRNA) loci. While some produce bona fide functional transcripts, others exert transcript-independent regulatory effects. Here, we describe MYNRL15: a noncoding regulatory locus on chromosome 15 and pan-myeloid leukemia dependency identified by a CRISPRi screen of lncRNA signatures from hematopoietic stem and progenitor cells (HSPCs) and acute myeloid leukemia (AML) samples. We demonstrate that the loss of cis-regulatory DNA elements in the locus, rather than its transcriptional products, drives its perturbation phenotype, triggering a global downregulation of oncogenic pathways, coordinated dysregulation of chromosome 15 neighborhoods, and formation of a tumor-suppressive, long-range chromatin interaction with the base of a distal loop. In addition, MYNRL15 perturbation selectively impaired primary AML blasts over normal HSPCs in vitro, and depleted patient-derived xenografts in vivo, providing evidence for oncogenic vulnerabilities at chromatin-regulating, noncoding loci. MYNRL15 The noncoding genome presents a largely untapped source of new biological insights, including thousands of long noncoding RNA (lncRNA) loci. While some produce bona fide functional transcripts, others exert transcript-independent regulatory effects. Here, we describe MYNRL15: a noncoding regulatory locus on chromosome 15 and pan-myeloid leukemia dependency identified by a CRISPRi screen of lncRNA signatures from hematopoietic stem and progenitor cells (HSPCs) and acute myeloid leukemia (AML) samples. We demonstrate that the loss of cis-regulatory DNA elements in the locus, rather than its transcriptional products, drives its perturbation phenotype, triggering a global downregulation of oncogenic pathways, coordinated dysregulation of chromosome 15 neighborhoods, and formation of a tumor-suppressive, long-range chromatin interaction with the base of a distal loop. In addition, MYNRL15 perturbation selectively impaired primary AML blasts over normal HSPCs in vitro, and depleted patient-derived xenografts in vivo, providing evidence for oncogenic vulnerabilities at chromatin-regulating, noncoding loci. ENA-FIRST-PUBLIC 2023-04-13 ENA-LAST-UPDATE 2023-04-13