Biology subjects

Guccione, E.

Publications and source records attributed to Guccione, E..

3 recordsLinked to original sources

bioRxiv2020

Npac Is a Co-factor of Histone H3K36me3 and Regulates Transcriptional Elongation in Mouse ES Cells

Chromatin modification contributes to pluripotency maintenance in embryonic stem cells (ESCs). However, the related mechanisms remain obscure. Here, we show that Npac, a "reader" of histone H3 lysine 36 trimethylation (H3K36me3), is required to maintain mouse ESC pluripotency since knockdown of Npac causes mouse ESC differentiation. Depletion of Npac in mouse embryonic fibroblasts (MEFs) inhibits reprogramming efficiency. Furthermore, our Npac ChIP-seq results reveal that Npac co-localizes with histone H3K36me3 in gene bodies of actively transcribed genes in mESCs. Interestingly, we find that Npac interacts with p-TEFb, RNA Pol II Ser2 and Ser5. Depletion of Npac disrupts transcriptional elongation of pluripotency genes Nanog and Rif1. Taken together, we propose that Npac is essential for transcriptional elongation of pluripotency genes by recruiting of p-TEFb and interacting with RNA Pol II Ser2 and Ser5.

molecular biology↗

bioRxiv2020

HNRNPM controls circRNA biogenesis and splicing fidelity to sustain prostate cancer cell fitness

Cancer cells are differentially dependent on the splicing machinery compared to normal untransformed cells. The splicing machinery thus represents a potential therapeutic target in cancer. To identify splicing factors important for prostate cancer cell (PCa) cell growth, we performed a parallel pooled shRNA screen on in vitro passaged cells and in vivo xenografted PCa tumor lines. Our screen revealed HNRNPM as a potential regulator of PCa cell growth. RNA- and eCLIP-sequencing data suggest that HNRNPM is bound to transcripts of key homeostatic genes and that loss of HNRNPM binding in a subset of these genes results in aberrant exon inclusion and exon back-splicing events in target transcripts. In both linear and circular mis-spliced transcripts, HNRNPM appears to preferentially bind to GU-rich elements in long flanking proximal introns. Mimicry of HNRNPM dependent linear splicing events using splice-switching antisense oligonucleotides (SSOs) was sufficient to inhibit cell growth in HNRNPM expressing cells. This suggests that prostate cancer cell dependence on HNRNPM is likely a result of mis-splicing of key homeostatic coding and non-coding genes. Taken together, our data reveal a role for HNRNPM in supporting prostate cancer cell fitness, and also as a potential therapeutic target in PCa.

genomics↗

bioRxiv2020

Deregulation of the histone H3K9 dimethylation landscape suppresses Wnt signaling in embryonal rhabdomyosarcoma

The Wnt signaling pathway is down-regulated in embryonal rhabdomyosarcoma (ERMS) and contributes to the block of myogenic differentiation. Epigenetic mechanisms leading to its suppression are unknown and could pave the way towards novel therapeutic modalities. In this study, we demonstrate that the H3K9 lysine methyltransferase G9a suppresses canonical Wnt signaling by activating expression of the Wnt antagonist DKK1. Inhibition of G9a expression or activity reduced DKK1 expression and elevated canonical Wnt signaling resulting in myogenic differentiation in vitro and in vivo. Mechanistically, G9a impacted Sp1 and p300 enrichment at the DKK1 promoter in a methylation-dependent manner. The reduced tumor growth upon G9a deficiency was reversed by recombinant DKK1 or LGK974, which also inhibits Wnt signaling. Consistently, among thirteen drugs targeting chromatin modifiers, G9a inhibitors were highly effective in reducing ERMS cell viability. Together, our study demonstrates that ERMS cells are vulnerable to G9a inhibitors and suggest that targeting the G9a-DKK1-{beta}-catenin node holds promise for differentiation therapy.

molecular biology↗