Project description:We analyzed the breadth and functional relationships of RNA Polymerase II pausing across many human and mouse cell types to understand what roles RNA Polymerase II pausing plays in gene regulation. We identified a novel association of H2A.Z at the TSS of increasingly paused genes. We knocked down H2A.Z to test whether H2A.Z positively or negatively affects RNA Polymerase II pausing to find that pausing globally increased upon knockdown.
Project description:Biochemical studies have established that the four-subunit negative elongation factor (NELF) complex mediates RNA polymerase II (Pol II) pausing at promoter proximal regions. Genetic ablation of individual NELF subunits destabilizes the entire NELF complex and causes lethality of cultured cells, leading to the prevailing concept that NELF-mediated Pol II pausing is essential for cell survival. Using separation-of-function mutations, we show here that NELFB’s effects on cell proliferation can be uncoupled from its function in Pol II pausing. NELFB mutants localized in the cytoplasm and incapacitated in the NELF complex assembly still retain their ability to support cell proliferation and at least part of NELFB-dependent transcriptome. Furthermore, we demonstrate that cytoplasmic NELFB physically and functionally interacts with multiple pro-survival signaling kinases, most notably PI3K/AKT. Enforced activation of PI3K/AKT-related kinases largely rescues deficiency of NELFB-depleted cells in proliferation, but not Pol II pausing. Together, these data revise the current understanding of the growth impact of Pol II pausing and underscore multiplicity of the biological function of individual NELF subunits.
Project description:Biochemical studies have established that the four-subunit negative elongation factor (NELF) complex mediates RNA polymerase II (Pol II) pausing at promoter proximal regions. Genetic ablation of individual NELF subunits destabilizes the entire NELF complex and causes lethality of cultured cells, leading to the prevailing concept that NELF-mediated Pol II pausing is essential for cell survival. Using separation-of-function mutations, we show here that NELFB’s effects on cell proliferation can be uncoupled from its function in Pol II pausing. NELFB mutants localized in the cytoplasm and incapacitated in the NELF complex assembly still retain their ability to support cell proliferation and at least part of NELFB-dependent transcriptome. Furthermore, we demonstrate that cytoplasmic NELFB physically and functionally interacts with multiple pro-survival signaling kinases, most notably PI3K/AKT. Enforced activation of PI3K/AKT-related kinases largely rescues deficiency of NELFB-depleted cells in proliferation, but not Pol II pausing. Together, these data revise the current understanding of the growth impact of Pol II pausing and underscore multiplicity of the biological function of individual NELF subunits.
Project description:RNA polymerase II (RNAPII) controls the expression of all protein coding genes and most noncoding loci in higher eukaryotes. The ultimate rate of transcription is regulated at the level of multiple checkpoints during the transcription cycle (initiation, pausing, termination). Calibrating the activity of RNAPII is fundamental to all cellular processes and requires an assortment of polymerase-associated factors that are recruited at sites of active transcription. The Integrator complex is one of the most elusive transcriptional regulators in metazoans, deemed to be recruited after initiation to help establish and modulate paused RNAPII. Recent structural, biochemical, and functional evidence suggest that Integrator is composed of 14 subunits that assemble and operate in a modular fashion. We employed proteomics and machine-learning structure prediction (AlphaFold2) approaches to identify a novel Integrator subunit, INTS15. We report that INTS15 assembles primarily with the INTS13/INTS14/INTS10 module and interfaces with the core of the Int-PP2A complex. Functional genomics analysis further reveals a role for INTS15 in modulating RNAPII pausing at a subset of genes in human cell lines. Our study shows that omics approaches combined with AlphaFold2-based predictions provide novel insights into the molecular architecture of large and flexible multiprotein complexes.