Project description:Transcriptional co-regulators, which mediate chromatin-dependent transcriptional signaling, represent tractable targets to modulate tumorigenic gene expression programs with small molecules. Genetic loss-of-function studies have recently implicated the transcriptional co-activator, ENL, as a selective requirement for the survival of acute leukemia – particularly those driven by multiple lineage leukemia (MLL)-fusion oncogenes. The YEATS domain of ENL, which binds to chromatin by interacting with acyl-lysine side chains, is critical for its pathogenic function in acute leukemiaand highlighted an essential role for its chromatin reader YEATS domain. Motivated by these recent discoveries, we executed a screen of nearly 300,000 small molecules to identify chromatin-competitiveand identified an amido-imidazopyridine inhibitors of the ENL YEATS domain (IC50 = 7 µM). Leveraging a SuFEx-based high-throughput approach to Optimizing an amido-imidazopyridine scaffold with highly parallelized, SuFEx-based medicinal chemistry optimization, we discovered SR-0813 (IC50 = 25 nM), a potent and selective ENL/AF9 YEATS domain inhibitor that exclusively inhibits the growth of ENL-dependent leukemia cell lines. Armed with this tool and a first-in-class ENL PROTAC, SR-1114, we detailed the response of AML cells to pharmacological ENL disruption for the first time. Most notably, displacement of In AML cells, SR-0813 evicts ENL from chromatin, by SR-0813 preferentially suppresseselicited a strikingly selective suppression of ENL target genes, including HOXA9/10, MYB, MYC and a number of other leukemia proto-oncogenes. Our study reproduces a number of key observations previously made by CRISPR/Cas9 loss of function and dTAG-mediated degradation, and therefore, both reinforces ENL as an emerging leukemia target and validates SR-0813 as a high-quality chemical probe.
Project description:Transcriptional co-regulators, which mediate chromatin-dependent transcriptional signaling, represent tractable targets to modulate tumorigenic gene expression programs with small molecules. Genetic loss-of-function studies have recently implicated the transcriptional co-activator, ENL, as a selective requirement for the survival of acute leukemia – particularly those driven by multiple lineage leukemia (MLL)-fusion oncogenes. The YEATS domain of ENL, which binds to chromatin by interacting with acyl-lysine side chains, is critical for its pathogenic function in acute leukemiaand highlighted an essential role for its chromatin reader YEATS domain. Motivated by these recent discoveries, we executed a screen of nearly 300,000 small molecules to identify chromatin-competitiveand identified an amido-imidazopyridine inhibitors of the ENL YEATS domain (IC50 = 7 µM). Leveraging a SuFEx-based high-throughput approach to Optimizing an amido-imidazopyridine scaffold with highly parallelized, SuFEx-based medicinal chemistry optimization, we discovered SR-0813 (IC50 = 25 nM), a potent and selective ENL/AF9 YEATS domain inhibitor that exclusively inhibits the growth of ENL-dependent leukemia cell lines. Armed with this tool and a first-in-class ENL PROTAC, SR-1114, we detailed the response of AML cells to pharmacological ENL disruption for the first time. Most notably, displacement of In AML cells, SR-0813 evicts ENL from chromatin, by SR-0813 preferentially suppresseselicited a strikingly selective suppression of ENL target genes, including HOXA9/10, MYB, MYC and a number of other leukemia proto-oncogenes. Our study reproduces a number of key observations previously made by CRISPR/Cas9 loss of function and dTAG-mediated degradation, and therefore, both reinforces ENL as an emerging leukemia target and validates SR-0813 as a high-quality chemical probe.
Project description:Recurrent chromosomal translocations involving the mixed lineage leukemia gene (MLL) give rise to highly aggressive acute leukemia associated with poor clinical outcomes. The preferential involvement of chromatin-associated factors in MLL rearrangements belies a dependency on transcriptional control. To identify new targets for therapeutic development in MLL, we performed a genome-scale CRISPR-Cas9 knockout screen in MLL-AF4 leukemia. Among validated targets, we identified the transcriptional regulator, ENL, as an unrecognized dependency particularly indispensable for proliferation. To explain the mechanistic role for ENL in leukemia pathogenesis and the dynamic role in transcription control, we pursued a chemical genetic strategy utilizing targeted protein degradation. ENL loss suppresses transcription initiation and elongation genome-wide, with pronounced effects at genes featuring disproportionate ENL load. Importantly, ENL-dependent leukemic growth was contingent upon an intact YEATS epigenomic reader domain. These findings reveal a novel dependency in acute leukemia and a first mechanistic rationale for disrupting YEATS domains in disease.
Project description:Recurrent chromosomal translocations involving the mixed lineage leukemia gene (MLL) give rise to highly aggressive acute leukemia associated with poor clinical outcomes. The preferential involvement of chromatin-associated factors in MLL rearrangements belies a dependency on transcriptional control. To identify new targets for therapeutic development in MLL, we performed a genome-scale CRISPR-Cas9 knockout screen in MLL-AF4 leukemia. Among validated targets, we identified the transcriptional regulator, ENL, as an unrecognized dependency particularly indispensable for proliferation. To explain the mechanistic role for ENL in leukemia pathogenesis and the dynamic role in transcription control, we pursued a chemical genetic strategy utilizing targeted protein degradation. ENL loss suppresses transcription initiation and elongation genome-wide, with pronounced effects at genes featuring disproportionate ENL load. Importantly, ENL-dependent leukemic growth was contingent upon an intact YEATS epigenomic reader domain. These findings reveal a novel dependency in acute leukemia and a first mechanistic rationale for disrupting YEATS domains in disease.
Project description:To investigate the contribution of ENL YEATS domain and downstream sequences in MLL-ENL leukemogenesis program, we generated MLL-ENL and MLL-ENL ∆YEATS (ENL aa372-559) cell lines by retrovirally introducing these constructs into lineage negative hematopoietic stem and progenitor cells (HSPCs).
Project description:The recognition of modified histones by “reader” proteins constitutes a key mechanism regulating gene expression in the chromatin context. Compared with the great variety of readers for histone methylation, few protein modules that recognize histone acetylation are known. Here we show that the evolutionarily conserved YEATS domains constitute a novel family of acetyllysine readers. The human AF9 YEATS domain binds strongly to histone H3K9 acetylation and, to a lesser extent, H3K27 and H3K18 acetylation. Crystal structural studies revealed that AF9 YEATS adopts an eight-stranded immunoglobin fold and utilizes a serine-lined aromatic “sandwiching” cage for acetyllysine readout, representing a novel recognition mechanism that is distinct from that of known acetyllysine readers. Histone acetylation recognition by AF9 is important for the chromatin recruitment of the H3K79 methyltransferase DOT1L. Together, our studies identify the YEATS domain as a novel acetyllysine-binding module, thereby establishing the first direct link between histone acetylation and DOTL1-mediated H3K79 methylation in transcription control. ChIP-seq analysis of AF9, H3K79me3, H3K9ac in Hela cells and H3K79me3 in Hela AF9 knockdown and Hela Dot1L knockdown cells.
Project description:Cancer cells are characterized by aberrant epigenetic landscapes and often exploit the chromatin machinery to activate oncogenic gene expression programs1. The recognition of modified histones by “reader” proteins constitutes a key mechanism underlying these processes; therefore targeting such pathways holds clinical promise, as exemplified by the recent development of BET bromodomain inhibitors2,3. We recently identified the YEATS domain as a novel acetyllysine-binding module4, yet its functional importance in human cancer remains unknown. Here we show that the YEATS domain-containing protein ENL, but not its paralog AF9, is required for disease maintenance in a variety of acute myeloid leukaemias (AML). CRISPR-Cas9 mediated depletion of ENL led to anti-leukemic effects, including increased terminal myeloid differentiation and suppression of leukaemia growth in vitro and in vivo. Biochemical and crystal structural studies in vitro and ChIP-seq analyses in leukaemia cells revealed that ENL binds to acetylated histone H3, and colocalizes with H3K27ac and H3K9ac on the promoters of actively transcribed genes that are essential for leukaemias. Disrupting the interaction between the YEATS domain and histone acetylation via structure-based mutagenesis reduced RNA polymerase II recruitment on ENL target genes, thus leading to suppression of oncogenic gene expression programs. Importantly, disruption of ENL’s functionality further sensitized leukaemia cells to BET inhibitors. Together, our study identifies ENL as a histone acetylation reader that regulates oncogenic transcriptional programs in AML and suggests that displacement of ENL from chromatin is a promising epigenetic therapy alone or in combination with BET inhibitors for AML