LEDGF/p75 promotes transcriptional pausing through preventing SPT5 phosphorylation
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ABSTRACT:
PROVIDER: PRJNA1053782 | ENA |
REPOSITORIES: ENA
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Project description:The transcriptional progression is regulated by SPT5, which is involved in both promoter-proximal RNA polymerase II (Pol II) pausing and elongation, which serve as rate-limiting steps in metazoan. However, the mechanism for SPT5 coordinating these processes remains unclear. Here we report that the disordered sub-regions within SPT5 contain a prion-like domain (PLD) that is required for Pol II pausing, while the phosphorylation site-rich domain (PRD) is essential for transcript elongation. Mechanically, SPT5-PLD helps stabilize Pol II pausing by preventing SPT5-PRD phosphorylation mediated by the super elongation complex (SEC). SPT5-PLD also maintains Pol II pausing by recruiting a newly identified transcriptional pause regulator, PSIP1, which inhibits phosphorylation required for elongation. Additionally, SPT5-PLD prevents premature release of Pol II pausing through PSIP1’s IBD domain by counteracting SEC. Our results demonstrate that SPT5 possesses intrinsic characteristics that balance the transcriptional process by preventing premature pause release and promoting progression to elongation.
2025-01-08 | GSE250380 | GEO
Project description:The study has been focused on the characterization of the role of LEDGF/p75 in chemiresistance in pediatric leukemia Abstract: MLL is an aggressive subtype of leukemia with a poor prognosis that mostly affects pediatric patients. MLL-rearranged fusion proteins (MLLr) induce aberrant target gene expression resulting in leukemogenesis. MLL and its fusions are tethered to chromatin by LEDGF/p75, a transcriptional co-activator that specifically recognizes H3K36me2/3. LEDGF/p75 is ubiquitously expressed and associated with regulation of gene expression, autoimmune responses and HIV replication. LEDGF/p75 was proven to be essential for leukemogenesis in MLL. Apart from MLL, LEDGF/p75 has been linked to lung, breast and prostate cancer. Intriguingly, LEDGF/p75 interacts with Med-1, which co-localizes with BRD4. Both are known as co-activators of super-enhancers. Here, we describe LEDGF/p75-dependent chemoresistance of MLLr cell lines. Investigation of the underlying mechanism revealed a role of LEDGF/p75 in the cell cycle and in survival pathways and showed that LEDGF/p75 protects against apoptosis during chemotherapy. Remarkably, LEDGF/p75 levels also affected expression of BRD4 and Med1. Altogether, our data suggest a role of LEDGF/p75 in cancer survival, stem cell renewal, and activation of nuclear super enhancers.
2021-01-14 | GSE164751 | GEO
Project description:Mixed-lineage leukemia (MLL) represents a genetically distinct and aggressive subset of human acute leukemia carrying chromosomal translocations of the MLL gene. These translocations result in oncogenic fusions that mediate aberrant recruitment of transcription machinery to MLL target genes. The N-terminus of MLL and MLL-fusions form a complex with Lens Epithelium-Derived Growth Factor (LEDGF/p75; encoded by the Psip1 gene) and MENIN. This complex contributes to the association of MLL and MLL-fusion multiprotein complexes with chromatin. Several studies have shown that both MENIN and LEDGF/p75 are required for efficient MLL fusion-mediated transformation and for the expression of downstream MLL-regulated genes like HOXA9 and MEIS1. In light of the development of a therapeutic strategy targeting this complex, understanding the function of LEDGF/p75 in normal hematopoiesis is crucial. We generated a conditional Psip1 knockout mouse model in the hematopoietic compartment and examined the effects of LEDGF/p75 depletion in postnatal hematopoiesis and the initiation of MLL leukemogenesis. Psip1 knockout mice were viable but showed several defects in hematopoiesis, reduced colony-forming activity in vitro, decreased expression of Hox genes in hematopoietic stem cells and decreased MLL occupancy at MLL target genes. Finally, in vitro and in vivo experiments showed that LEDGF/p75 is dispensable for steady state hematopoiesis but essential for the initiation of MLL-mediated leukemia. These data corroborate the MLL-LEDGF/p75 interaction as novel target for the treatment of MLL-rearranged leukemia.
2017-09-30 | GSE104138 | GEO
Project description:Role of LEDGF/p75 in MLL chemoresistance
| PRJNA691895 | ENA
Project description:Mixed lineage leukemia-rearranged (MLLr) leukemia is a genetically distinct subtype of leukemia driven by a reciprocal chromosomal translocation or partial tandem duplications of internal coding regions of the MLL gene KMT2A. These rearrangements result in in-frame genes, translated to oncogenic fusion proteins deregulating the MLL target genes (e.g. HoxA family, Meis1, Cdk6), promoting leukemogenesis and tumor progression. To regulate gene expression, unstructured N-terminal motifs found in MLL form a ternary complex with menin and the integrase binding domain (IBD) of the p75 splice variant of Lens Epithelium Derived Growth Factor (LEDGF/p75). Formation of the ternary complex is crucial for MLL-r leukemogenesis. Hepatoma derived growth factor related protein 2 (HRP2) is the only human paralog of LEDGF/p75 with identical functional domains. We investigated its role in normal hematopoiesis and leukemia. We demonstrate that adult Hrp2 knockout mice can be distinguished from their wild type littermates by increased neutrophils in the hematopoietic system. Colony formation experiments and Gene Set Enrichment Analysis on lin- HSC hinted towards a stem-like state supported by HRP2. In context of leukemia, we observe a more general role for HRP2 in the survival of leukemic cells independently of MLL.
2020-07-11 | GSE154202 | GEO
Project description:The pause-release model of transcription proposes that pol II pauses 40-100 bases from the start site resulting in a pile-up that is relieved by subsequent release into productive elongation. Pause release is facilitated by PTEFb phosphorylation of the pol II elongation factor, Spt5. We mapped paused polymerases by eNETseq and found frequent pausing in zones that extend ~0.3-3kb into genes, even when PTEFb is inhibited. The fraction of paused polymerases or “pausiness” declines gradually over several kb, and not abruptly as predicted for a discrete pause release event. Spt5 depletion extends pausing zones suggesting that it promotes maturation of elongation complexes to a low-pausing state. Expression of mutants after Spt5 depletion showed that phosphomimetic substitutions in the Spt5 CTR1 domain diminished pausing throughout genes. In contrast mutants that prevent phosphorylation of the Spt5 RNA-binding domain strengthened pausing. Thus distinct Spt5 phospho-isoforms set the balance between pausing and elongation.
2022-10-01 | GSE202749 | GEO
Project description:LEDGF/p75 is Dispensable for Hematopoiesis but Essential for MLL-rearranged Leukemogenesis
| PRJNA411792 | ENA
Project description:Role of HRP2 in mixed lineage leukemia compared to its paralog LEDGF/p75
| PRJNA645412 | ENA
Project description:The pluripotency of embryonic stem cells (ESCs) relies on appropriate responsiveness to developmental cues. Promoter-proximal pausing of RNA polymerase II (Pol II) has been suggested to play a role in keeping genes poised for future activation. To identify the role of Pol II pausing in regulating ESC pluripotency, we have generated mouse ESCs carrying a mutation in the pause-inducing factor SPT5. Consistent with previous in vitro studies showing the pausing deficiency of this mutant SPT5, our genomic analysis reveals genome-wide reduction of paused Pol II in mutant mESCs. Furthermore, we find that genes differentially regulated by mutant SPT5 correlates with distinct chromatin states. Functionally, this pausing-deficient SPT5 disrupts ESC differentiation without affecting self-renewal. Thus, our study uncovers an important role of Pol II pausing in regulating ESC differentiation and also suggests that Pol II pausing can both positively and negatively influence transcription depending on the local chromatin environment.
2017-12-08 | GSE99747 | GEO
Project description:The pluripotency of embryonic stem cells (ESCs) relies on appropriate responsiveness to developmental cues. Promoter-proximal pausing of RNA polymerase II (Pol II) has been suggested to play a role in keeping genes poised for future activation. To identify the role of Pol II pausing in regulating ESC pluripotency, we have generated mouse ESCs carrying a mutation in the pause-inducing factor SPT5. Consistent with previous in vitro studies showing the pausing deficiency of this mutant SPT5, our genomic analysis reveals genome-wide reduction of paused Pol II in mutant mESCs. Furthermore, we find that genes differentially regulated by mutant SPT5 correlates with distinct chromatin states. Functionally, this pausing-deficient SPT5 disrupts ESC differentiation without affecting self-renewal. Thus, our study uncovers an important role of Pol II pausing in regulating ESC differentiation and also suggests that Pol II pausing can both positively and negatively influence transcription depending on the local chromatin environment.
2017-12-08 | GSE99746 | GEO