Nuclear coactivator-62 kDa/Ski-interacting protein is a nuclear matrix-associated coactivator that may couple vitamin D receptor-mediated transcription and RNA splicing
Department of Cell Biology; Graduate School of Biomedical Sciences
Life Sciences | Medicine and Health Sciences
Nuclear coactivator-62 kDa/Ski-interacting protein (NCoA62/SKIP) is a putative vitamin D receptor (VDR) and nuclear receptor coactivator protein that is unrelated to other VDR coactivators such as those in the steroid receptor coactivator (SRC) family. The mechanism through which NCoA62/SKIP functions in VDR-activated transcription is unknown. In the present study, we identified a nuclear localization sequence in the COOH terminus of NCoA62/SKIP and showed that NCoA62/SKIP was targeted to nuclear matrix subdomains. Chromatin immunoprecipitation studies revealed that endogenous NCoA62/SKIP associated in a 1,25-dihydroxyvitamin D3-dependent manner with VDR target genes in ROS17/2.8 osteosarcoma cells. A cyclic pattern of promoter occupancy by VDR, SRC-1, and NCoA62/SKIP was observed, with NCoA62/SKIP entering these promoter complexes after SRC-1. These studies provide strong support for the proposed role of NCoA62/SKIP as a VDR transcriptional coactivator, and they indicate that key mechanistic differences probably exist between NCoA62/SKIP and SRC coactivators. To explore potential mechanisms, NCoA62/SKIP-interacting proteins were purified from HeLa cell nuclear extracts and identified by mass spectrometry. The identified proteins represent components of the spliceosome as well as other nuclear matrix-associated proteins. Here, we show that a dominant negative inhibitor of NCoA62/SKIP (dnNCoA62/SKIP) interfered with appropriate splicing of transcripts derived from 1,25-dihydroxyvitamin D3-induced expression of a growth hormone minigene cassette. Taken together, these data show that NCoA62/SKIP has properties that are consistent with those of nuclear receptor coactivators and with RNA spliceosome components, thus suggesting a potential role for NCoA62/SKIP in coupling VDR-mediated transcription to RNA splicing.
DOI of Published Version
J Biol Chem. 2003 Sep 12;278(37):35325-36. Epub 2003 Jul 2. Link to article on publisher's site
The Journal of biological chemistry
Zhang C, Dowd DR, Staal A, Gu C, Lian JB, Van Wijnen AJ, Stein GS, MacDonald PN. (2003). Nuclear coactivator-62 kDa/Ski-interacting protein is a nuclear matrix-associated coactivator that may couple vitamin D receptor-mediated transcription and RNA splicing. Morningside Graduate School of Biomedical Sciences Student Publications. https://doi.org/10.1074/jbc.M305191200. Retrieved from https://escholarship.umassmed.edu/gsbs_sp/722