Multilayered Control of Alternative Splicing Regulatory Networks by Transcription Factors
MOLECULAR CELL
Authors: Han, Hong; Braunschweig, Ulrich; Gonatopoulos-Pournatzis, Thomas; Weatheritt, Robert J.; Hirsch, Calley L.; Ha, Kevin C. H.; Radovani, Ernest; Nabeel-Shah, Syed; Sterne-Weiler, Tim; Wang, Juli; O'Hanlon, Dave; Pan, Qun; Ray, Debashish; Zheng, Hong; Vizeacoumar, Frederick; Datti, Alessandro; Magomedova, Lilia; Cummins, Carolyn L.; Hughes, Timothy R.; Greenblatt, Jack F.; Wrana, Jeffrey L.; Moffat, Jason; Blencowe, Benjamin J.
Abstract
Networks of coordinated alternative splicing (AS) events play critical roles in development and disease. However, a comprehensive knowledge of the factors that regulate these networks is lacking. We describe a high-throughput system for systematically linking trans-acting factors to endogenous RNA regulatory events. Using this system, we identify hundreds of factors associated with diverse regulatory layers that positively or negatively control AS events linked to cell fate. Remarkably, more than one-third of the regulators are transcription factors. Further analyses of the zinc finger protein Zfp871 and BTB/POZ domain transcription factor Nacc1, which regulate neural and stem cell AS programs, respectively, reveal roles in controlling the expression of specific splicing regulators. Surprisingly, these proteins also appear to regulate target AS programs via binding RNA. Our results thus uncover a large "missing cache'' of splicing regulators among annotated transcription factors, some of which dually regulate AS through direct and indirect mechanisms.
Nucleus Accumbens-Associated 1 Contributes to Cortactin Deacetylation and Augments the Migration of Melanoma Cells
JOURNAL OF INVESTIGATIVE DERMATOLOGY
Authors: Tsunoda, Kanako; Oikawa, Hiroki; Tada, Hiroshi; Tatemichi, Yoshinori; Muraoka, Sosuke; Miura, Shinpei; Shibazaki, Masahiko; Maeda, Fumihiko; Takahashi, Kazuhiro; Akasaka, Toshihide; Masuda, Tomoyuki; Maesawa, Chihaya
Abstract
We investigated the prognostic significance and post-transcriptional acetylation-modification of cortactin (CTTN) via the nucleus accumbens-associated 1 (NACC1)-histone deacetylase 6 (HDAC6) deacetylation system in primary melanomas and melanoma cell lines. Overexpression of CTTN protein was observed in 56 (73%) of 77 stage I-IV melanomas, and was significantly correlated with tumor thickness, lymph node metastasis, distant metastasis, and disease outcome. The patients whose tumors exhibited CTTN overexpression had a poorer outcome than patients without this feature (P=0.028, log-rank test). NACC1 and CTTN proteins, but not HDAC6, were overexpressed in four melanoma cell lines in comparison with a primary culture of normal human epidermal melanocytes. Knockdown of both NACC1 and HDAC6 markedly downregulated the migration activity of all melanoma cell lines (P<0.05), and induced a gain of CTTN protein acetylation status. Confocal microscopy showed that hyperacetylation of CTTN modulated by depletion of both NACC1 and HDAC6 induced disappearance of CTTN protein at the leading edge of migrating cells, resulting in stabilization of the focal adhesion structure and development of actin stress fibers. These data suggest that the acetylation status of CTTN modulated by the NACC1-HDAC6 deacetylation system induces acceleration of melanoma cell migration activity via an actin-dependent cellular process, possibly contributing to aggressive behavior (invasion/metastasis) of the melanoma cells.