Mechanisms of gene regulation by the mammalian Integrator-PP2A complex

• Applicant: Dr. Apoorva Baluapuri
• Subject Area: Biochemistry
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 511798779

It was recently discovered by the lab of Karen Adelman (Harvard Medical School) that the Integrator complex (INT) associates specifically with the protein phosphatase PP2A and recruits it to RNA polymerase II (Pol II) to directly mediate dephosphorylation of the Pol II C-terminal domain (CTD) and transcription elongation factors. By antagonizing the phosphorylation events required to enable Pol II pause release and productive elongation, INT-PP2A drives transcription termination at selected genes and potently attenuates expression. Targets of INT are enriched in pathways that govern cell growth, immune and stress responses, underscoring a role for INT in cancer. Moreover, we found increased phosphorylation of MYC in cancer cells upon disruption of INT-PP2A association, suggesting that INT is central for PP2A-mediated dephosphorylation of both the transcription machinery and critical transcriptional regulators.The overarching goal of my project is to dissect the direct role of INTS8 & INTS11 and identify small molecules that specifically stimulate or disrupt the association of PP2A with INT to control expression of growth and stress responsive genes in cancer cells, or to sensitize cells to DNA damaging chemotherapeutics. Further, this will illuminate the functional antagonism between transcriptional kinases and PP2A in regulation of gene networks, by precisely defining the gene expression changes that result from modulation of kinase and phosphatase activity with small molecules.In summary, this project will (A) Dissect the direct role of INTS8 & INTS11 (the phosphatase and endonuclease activity governing subunits respectively) in transcription of genes and enhancers utilizing auxin induced protein degradation and nascent RNA-sequencing.(B) Characterize the transcriptional effects of modulating INT activity in conjunction with inhibition of transcriptional kinases CDK9 and CDK12/13, using advanced nascent RNA profiling methods complemented with proteomics and integrative computational analyses.(C) Identify novel small-molecule modulators of INT-PP2A interaction, particularly ones which disrupt phosphatase (rather than endonuclease) functions of INT and offer a therapeutic benefit in cancer cell lines (like breast cancer).

• DFG Programme: WBP Fellowship
• International Connection: USA
• Host: Professorin Karen Adelman, Ph.D.