No abstract

The highly conserved zinc-finger protein, CTCF, is a candidate tumor suppressor protein that binds to highly divergent DNA sequences. CTCF has been connected to multiple functions in chromatin organization and gene regulation including chromatin insulator activity and transcriptional enhancement and silencing. Here we show that CTCF harbors several autonomous repression domains. One of these domains, the zinc-finger cluster, silences transcription in all cell types tested and binds directly to the co-repressor SIN3A. Two distinct regions of SIN3A, the PAH3 domain and the extreme C-terminal region, bind independently to this zinc-finger cluster. Analysis of nuclear extract from HeLa cells revealed that CTCF is also capable of retaining functional histone deacetylase activity. Furthermore, the ability of regions of CTCF to retain deacetylase activity correlates with the ability to bind to SIN3A and to repress gene activity. We suggest that CTCF driven repression is mediated in part by the recruitment of histone deacetylase activity by SIN3A.

Mammalian target of rapamycin (mTOR) is a key protein kinase that regulates cell growth, metabolism, and autophagy to maintain cellular homeostasis. Its activity is inhibited by adverse conditions, including nutrient limitation, hypoxia, and DNA damage. In this study, we demonstrate that Che-1, a RNA polymerase II-binding protein activated by the DNA damage response, inhibits mTOR activity in response to stress conditions. We found that, under stress, Che-1 induces the expression of two important mTOR inhibitors, Redd1 and Deptor, and that this activity is required for sustaining stress-induced autophagy. Strikingly, Che-1 expression correlates with the progression of multiple myeloma and is required for cell growth and survival, a malignancy characterized by high autophagy response.

Introduction: Molecular characterization studies revealed recurrent kelch like ECH associated protein 1 gene (KEAP1)/nuclear factor, erythroid 2 like 2 gene (NFE2L2) alterations in NSCLC. These genes encode two interacting proteins (a stress response pathway [SRP]) that mediate a cytoprotective response to oxidative stress and xenobiotics. Nevertheless, whether KEAP1/NFE2L2 mutations have an impact on clinical outcomes is unclear. Methods: We performed amplicon-based next-generation sequencing to characterize the SRP in patients with metastatic NSCLC (Regina Elena National Cancer Institute cohort [n ¼ 88]) treated with first-line chemotherapy. Mutations in the DNA damage response (tumor protein p53 gene [TP53], ATM serine/threonine kinase gene [ATM], and ATR serine/threonine kinase gene [ATR]) were concomitantly analyzed. In lung adenocarcinoma (LAC), we also determined the expression of phosphorylated ataxia telangiectasia mutated kinase and ataxia telangiectasia and Rad3-related protein. Two independent cohorts (the Memorial Sloan Kettering Cancer Center cohort and The Cancer Genome Atlas cohort) with data from approximately 1400 patients with advanced LAC were used to assess the reproducibility of the results.Results: In the Regina Elena National Cancer Institute cohort, patients whose tumors carried mutations in the KEAP1/NFE2L2 pathway had significantly shorter progression-free survival and overall survival than their wild-type counterparts did (log-rank p ¼ 0.006 and p ¼ 0.018, respectively). This association was driven by LAC in which KEAP1/NFE2L2 mutations were overrepresented in

The activity of the nuclear factor-Y (NF-Y) transcription factor is restricted to proliferating cells in vitro. We engineered transgenic mice that enabled bioluminescence imaging of NF-Y activity in every area of the body. We visualized areas of proliferation, and we highlight for the first time a role of NF-Y activity in hepatocyte proliferation during liver regeneration.