Targeting Processive Transcription Elongation via SEC Disruption for MYC-Induced Cancer Therapy
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ABSTRACT:
PROVIDER: PRJNA448451 | ENA |
REPOSITORIES: ENA
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Project description:The super elongation complex (SEC) is required for robust and productive transcription through release of RNA polymerase II (Pol II) with its P-TEFb module and promoting transcriptional processivity with its ELL2 subunit. Malfunction of SEC contributes to multiple human diseases including cancer. Here, we identify peptidomimetic lead compounds, KL-1 and its structural homolog KL-2, which disrupt the interaction between the SEC scaffolding protein AFF4 and P-TEFb, resulting in impaired release of Pol II from promoter-proximal pause sites and a reduced average rate of processive transcription elongation. SEC is required for induction of heat-shock genes and treating cells with KL-1 and KL-2 attenuates the heat-shock response from Drosophila to human. SEC inhibition downregulates MYC and MYC-dependent transcriptional programs in mammalian cells and delays tumor progression in a mouse xenograft model of MYC-driven cancer, indicating that small-molecule disruptors of SEC could be used for targeted therapy of MYC-induced cancer.
2018-10-26 | GSE112608 | GEO
Project description:MYCN amplification in neuroblastoma predicts particular poor prognosis and directly targeting of MYCN remains a major challenge. We conducted a targeted screen of transcription elongation factors and identified the super elongation complex (SEC) as a unique vulnerability in MYCN-amplified neuroblastoma. Mechanistically, MYCN directly interacts with the SEC subunit EAF1 and recruits the complex to the target gene loci for ensuing processive transcription elongation, rendering MYCN-mediated transcriptional activation highly dependent on SEC. Pharmacological inhibition of SEC by KL-1 or KL-2 elicits selective cell death in MYCN-overexpressing neuroblastoma cells. Furthermore, drug combination screening identifies the BCL-2 inhibitor ABT-199 synergistic with KL-2. Pre-clinical studies manifest that KL-2 and ABT-199 co-treatment significantly suppresses tumorigenesis and shows therapeutic value in multiple neuroblastoma allograft and xenograft models. These findings highlight SEC as a targetable vulnerability, and simultaneous inhibition of SEC and BCL-2 holds great promise for the treatment of MYCN-driven neuroblastoma.
2023-02-27 | GSE199086 | GEO
Project description: Not available
| S-EPMC6422358 | biostudies-literature
Project description:The MYC oncoprotein binds to promoter-proximal regions of virtually all transcribed genes and is expressed in a strictly growth factor-dependent manner in non-tumor cells. Here we show that MYC directly binds SPT5, a subunit of the RNA polymerase II (POL2) elongation factor DSIF. MYC recruits SPT5 to genes and enables the CDK7-dependent transfer of SPT5 onto POL2. Consistent with known functions of SPT5, MYC is required for fast and processive transcription elongation. In addition, MYC increases the directionality of promoters by stimulating sense transcription and suppressing the synthesis of antisense RNAs. Our results argue that MYC controls the productive assembly of POL2 with general elongation factors to form processive elongation complexes. The high levels of MYC that are expressed in tumors sequester SPT5 into non-functional complexes, slows transcription at growth-suppressive genes and promotes uncontrolled cellular growth.
2019-03-27 | GSE115365 | GEO
Project description:MYCN amplification in neuroblastoma leads to aberrant expression of MYCN oncoprotein, which binds active genes promoting transcriptional amplification. Yet how MYCN coordinates transcription elongation to meet productive transcriptional amplification and which elongation machinery represents MYCN-driven vulnerability remain to be identified. We conducted a targeted screen of transcription elongation factors and identified the super elongation complex (SEC) as a unique vulnerability in MYCN-amplified neuroblastomas. MYCN directly binds EAF1 and recruits SEC to enhance processive transcription elongation. Depletion of EAF1 or AFF1/AFF4, another core subunit of SEC, leads to a global reduction in transcription elongation and elicits selective apoptosis of MYCN-amplified neuroblastoma cells. A combination screen reveals SEC inhibition synergistically potentiates the therapeutic efficacies of FDA-approved BCL2 antagonist ABT-199, in part due to suppression of MCL1 expression, both in MYCN-amplified neuroblastoma cells and in patient-derived xenografts. These findings identify disruption of the MYCN-SEC regulatory axis as a promising therapeutic strategy in neuroblastoma.
2023-05-10 | PXD039332 | Pride
Project description:MYC Recruits SPT5 to RNA Polymerase II to Promote Processive Transcription Elongation
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Project description:Cyclin-dependent kinase 12 (CDK12) interacts with Cyclin K to form a a functional nuclear kinase complex, which has been reported to phosphorylate the carboxyl-terminal domain (CTD) of RNA polymerase II (Pol II) for transcriptional regulation and co-transcriptional RNA processing. However, the precise mechanisms and targets of CDK12 action remain largely unknown. Here, we combined a chemical genetic screen and phosphoproteomic strategies and identified a landscape of nuclear CDK12 substrates, which included proteins that regulate transcription, chromatin organization, and RNA splicing. Next, we confirmed that the LEO1 subunit of the transcription elongation factor PAF1 complex (PAF1C) is a bona fide substrate of CDK12. Acute depletion of LEO1 reduces Pol II occupancy on the chromatin, while mutations of LEO1 phosphorylation sites to non-phosphorylatable alanine residues attenuated the association of PAF1C with elongating Pol II and chromatin, resulting in impaired processive transcription elongation. Furthermore, LEO1 C-terminus could interact with and be dephosphorylated by the Integrator-PP2A complex (INTAC), while acute depletion of INTAC in cells promotes the association between PAF1C and elongating Pol II on the chromatin. Together, this study provides a novel transcriptional regulatory mechanism that the CDK12-INTAC axis fine-tunes LEO1 phosphorylation for processive transcription elongation.
2023-05-19 | GSE217544 | GEO
Project description:Cyclin-dependent kinase 12 (CDK12) interacts with Cyclin K to form a functional nuclear kinase that promotes processive transcription elongation through phosphorylation of the RNA polymerase II (Pol II) C-terminal domain (CTD). To gain a broader understanding of CDK12 cellular function, we used chemical-genetic and phosphoproteomic screening to identify a landscape of nuclear human CDK12 substrates, including regulators of transcription, chromatin organization, and RNA splicing. We further validated LEO1, a subunit of the PAF1 complex (PAF1C), as a bona fide cellular substrate of CDK12. Acute depletion of LEO1, or substituting LEO1 phosphorylation sites with alanine, attenuated PAF1C association with elongating Pol II and impaired processive transcription elongation. We also found that LEO1 interacts with, and is dephosphorylated by, the Integrator-PP2A complex (INTAC) and that INTAC promotes the association of PAF1C with Pol II. Together, this study reveals a previously unknown role for CDK12 and INTAC in regulating LEO1 phosphorylation for transcriptional regulation, providing important insights into gene transcription and its regulation.
2023-06-08 | PXD038558 | Pride
Project description:A CSB-PAF1C axis restores processive transcription elongation after DNA damage repair
| PRJNA591582 | ENA
Project description:The super elongation complex (SEC) contains the positive transcription elongation factor b (P-TEFb) and a subcomplex, ELL2-EAF1, which stimulates transcription elongation by RNA polymerase II (Pol II). Here we report the cryo-EM structure of ELL2-EAF1 bound to a Pol II elongation complex at 2.8 Å resolution. The ELL2-EAF1 dimerization module directly binds the Pol II lobe, explaining how SEC delivers P-TEFb to Pol II. The same site on the lobe also binds the initiation factor TFIIF, consistent with SEC binding only after the transition from transcription initiation to elongation. Structure-guided functional analysis shows that elongation stimulation requires the dimerization module and an ELL2 protein linker that tethers this module to the Pol II protrusion. Our results show that SEC stimulates elongation allosterically and indicate that this stimulation involves stabilization of a further closed conformation of the Pol II active center cleft.
2021-07-15 | PXD024457 | Pride