Project description:To understand better the contribution of CDK9 in P. gingivalis-stimulated gene expression, gene chips were performed. Lentiviral vectors carrying CDK9 shRNA or not were transfected into cells for 96 hours, with the assist of Envirus. NC group was transfected with non-targeting scramble and stimulated with PBS. NC and Pg group was transfected with non-targeting scramble and stimulated with P. gingivalis. CDK9 shRNA group was transfected with CDK9 shRNA and stimulated with PBS. CDK9 shRNA and Pg group was transfected with CDK9 shRNA and stimulated with P. gingivalis.
Project description:Primary outcome(s): The association of intestinal microbiota with gene mutations and gene expressions and clinicopathological factors in colorectal cancer and inflammatory bowel disease.
Project description:CDK9 is the kinase subunit of P-TEFb that enables RNA polymerase (Pol) II to transit from promoter-proximal pausing to productive elongation. Although considerable interest exists in CDK9 as a therapeutic target, little progress has been made due to the lack of highly selective inhibitors. Here, we describe the development of i-CDK9 as such an inhibitor that potently suppresses CDK9 phosphorylation of substrates and causes genome-wide Pol II pausing. While most genes experience reduced expression, MYC and other primary response genes increase expression upon sustained i-CDK9 treatment. Essential for this increase, the bromodomain protein BRD4 captures P-TEFb from 7SK snRNP to deliver to target genes and also enhances CDK9’s activity and resistance to inhibition. Because the i-CDK9-induced MYC expression and binding to P-TEFb compensate for P-TEFb’s loss of activity, only the simultaneous inhibition of CDK9 and MYC can efficiently induce growth arrest and apoptosis of cancer cells, suggesting the potential of a combinatorial treatment strategy. ChIP-seq of Pol II in HeLa cells before or after i-CDk9 treatment
Project description:Cyclin-Dependent Kinase 9 (CDK9) as part of the PTEFb complex promotes transcriptional elongation by promoting RNAPII pause release. We now report that, paradoxically, CDK9 is also essential for maintaining gene silencing at heterochromatic loci. Through a live cell screen, we discovered that CDK9 inhibition reactivates epigenetically silenced genes in cancer, leading to restored tumor suppressor gene expression and cell differentiation, along with activation of endogenous retrovirus (ERV) genes. CDK9 inhibition dephosphorylates the SWI/SNF protein SMARCA4 and represses HP1α expression, both of which contribute to gene reactivation. Based on gene activation, we developed the highly selective and potent CDK9 inhibitor MC180295 (IC50 =5.1nM) that has broad anti-cancer activity in-vitro and is effective in in-vivo cancer models. Additionally, CDK9 inhibition sensitizes with the immune checkpoint inhibitor α-PD-1 in vivo, making it an excellent target for epigenetic therapy of cancer.
Project description:CDK9 is the kinase subunit of P-TEFb that enables RNA polymerase (Pol) II to transit from promoter-proximal pausing to productive elongation. Although considerable interest exists in CDK9 as a therapeutic target, little progress has been made due to the lack of highly selective inhibitors. Here, we describe the development of i-CDK9 as such an inhibitor that potently suppresses CDK9 phosphorylation of substrates and causes genome-wide Pol II pausing. While most genes experience reduced expression, MYC and other primary response genes increase expression upon sustained i-CDK9 treatment. Essential for this increase, the bromodomain protein BRD4 captures P-TEFb from 7SK snRNP to deliver to target genes and also enhances CDK9’s activity and resistance to inhibition. Because the i-CDK9-induced MYC expression and binding to P-TEFb compensate for P-TEFb’s loss of activity, only the simultaneous inhibition of CDK9 and MYC can efficiently induce growth arrest and apoptosis of cancer cells, suggesting the potential of a combinatorial treatment strategy. We used microarrays to examine the global impact on gene expression by imhibiting CDK9 at different time durations. HeLa cell lines treated with CDK9 inhibitor at different time points
Project description:We characterized the CDK9 and Hes1 occupancy on gene loci in conditions of unstimuated and LPS stimualtion in BMDMs BMDMs were left untreated or stimulated with LPS for 1 hour. CDK9 or Hes1 ChIP was performed and the DNA products were subject to ChIPseq
Project description:Gene expression by RNA Polymerase II (RNAPII) is tightly controlled by Cyclindependent kinases (CDKs) at discrete checkpoints during the transcription cycle. The RNAPII pausing checkpoint, engaged after transcription initiation, is controlled by CDK9 to regulate transcription in metazoans. We discovered that CDK9-mediated RNAPII pause-release is functionally opposed by a protein phosphatase 2A (PP2A) complex. PP2A dynamically competes for key CDK9 substrates, DSIF and RNAPIICTD, and is recruited to transcription pausing sites by the Integrator complex subunit INTS6. INTS6 depletion confers resistance to CDK9 inhibition in a variety of normal and tumor cell lines. Loss of INTS6 abolishes the Integrator-PP2A association leading to unrestrained CDK9 activity, which amplifies transcriptional responses. Pharmacological PP2A activation synergizes with CDK9 inhibition to kill MLLrearranged leukemias and solid tumors and provide therapeutic benefit in vivo. These data demonstrate that finely-tuned gene expression relies on the balance of kinase and phosphatase activity at the pausing checkpoint.
Project description:In this study, we discovered that CDK9-mediated, RNAPII-driven transcription is functionally opposed by a protein phosphatase 2A (PP2A) complex that is recruited to transcription sites by the Integrator complex subunit INTS6. PP2A dynamically antagonises phosphorylation of key CDK9 substrates including DSIF and RNAPII-CTD. Loss of INTS6 results in resistance to tumor cell death mediated by CDK9 inhibition, decreased turnover of CDK9 phospho-substrates and amplification of acute cell growth and pro-inflammatory transcriptional responses. Pharmacological PP2A activation synergizes with CDK9 inhibition to kill both leukemic and solid tumor cells, providing therapeutic benefit in vivo. These data demonstrate that finely-tuned gene expression relies on the balance of kinase and phosphatase activity throughout the transcription cycle.
Project description:To determine the expression of genes in cells following silencing of CDK9 by siRNA. U2OS human osteosarcoma cell lines were utilized.