PRP19alpha and CDC5L are major components of the active spliceosome. However, their association process is still unknown. Here, we demonstrated that PRP19 alpha/14-3-3beta/CDC5L complex formation is regulated by Akt during nerve growth factor (NGF)-induced neuronal differentiation of PC12 cells. Analysis of PRP19 alpha mutants revealed that the phosphorylation of PRP19 alpha at Thr 193 by Akt was critical for its binding with 14-3-3beta to translocate into the nuclei and for PRP19 alpha/14-3-3beta/CDC5L complex formation in neuronal differentiation. Forced expression of either sense PRP19 alpha or sense 14-3-3beta RNAs promoted NGF-induced neuronal differentiation, whereas down-regulation of these mRNAs showed a suppressive effect. The nonphosphorylation mutant PRP19 alpha T193A lost its binding ability with 14-3-3beta and acted as a dominant-negative mutant in neuronal differentiation. These results imply that Akt-dependent phosphorylation of PRP19 alpha at Thr193 triggers PRP19 alpha/14-3-3beta/CDC5L complex formation in the nuclei, likely to assemble the active spliceosome against neurogenic pre-mRNAs.
"Since P19 EC cells possess many properties similar to ES cells established from mice and humans , it may be possible that the expression system of Meis1a can be utilized for the production of neurons from human ES cells in combination with the PRP19α expression system 23,52. "
[Show abstract][Hide abstract] ABSTRACT: Oct4 plays a critical role both in maintaining pluripotency and the cell fate decision of embryonic stem (ES) cells. Nonetheless, in the determination of the neuroectoderm (NE) from ES cells, the detailed regulation mechanism of the gene expression is poorly understood. Here, we report that crosstalk between Oct4 and Meis1a, a Pbx-related homeobox protein, is required for neural differentiation of mouse P19 embryonic carcinoma (EC) cells induced by retinoic acid (RA). During neural differentiation, Oct4 expression was transiently enhanced during 6-12 h of RA addition and subsequently disappeared within 48 h. Coinciding with up-regulation of Oct4 expression, the induction of Meis1a expression was initiated and reached a plateau at 48 h, suggesting that transiently induced Oct4 activates expression and the up-regulated Meis1a then suppresses expression. Chromatin immunoprecipitation (ChIP) and luciferase reporter analysis showed that Oct4 enhanced expression via direct binding to the promoter accompanying histone H3 acetylation and appearance of 5-hydoxymethylcytosine (5hmC), while Meis1a suppressed expression via direct association with the promoter together with histone deacetylase 1 (HDAC1). Furthermore, ectopic expression promoted neural differentiation via formation of large neurospheres that expressed Nestin, GLAST, BLBP and Sox1 as neural stem cell (NSC)/neural progenitor markers, whereas its down-regulation generated small neurospheres and repressed neural differentiation. Thus, these results imply that crosstalk between Oct4 and Meis1a on mutual gene expressions is essential for the determination of NE from EC cells.
PLoS ONE 02/2013; 8(2):e56997. DOI:10.1371/journal.pone.0056997 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Defective DNA repair is widely acknowledged to negatively impact on healthy aging, since mutations in DNA repair factors lead to accelerated and premature aging. However, the opposite, namely if improved DNA repair will also increase the life or health span is less clear, and only few studies have tested if overexpression of DNA repair factors modulates life and health span in cells or organisms. Recently, we identified and characterized SNEVhPrp19/hPso4, a protein that plays a role in DNA repair and pre-mRNA splicing, and observed a doubling of the replicative life span upon ectopic overexpression, accompanied by lower basal DNA damage and apoptosis levels as well as an increased resistance to oxidative stress. Here we find that SNEVhPrp19/hPso4 is phosphorylated at S149 in an ataxia telangiectasia mutated protein (ATM)-dependent manner in response to oxidative stress and DNA double strand break inducing agents. By overexpressing wild-type SNEVhPrp19/hPso4 and a phosphorylation-deficient point-mutant, we found that S149 phosphorylation is necessary for mediating the resistance to apoptosis upon oxidative stress and is partially necessary for elongating the cellular life span. Therefore, ATM dependent phosphorylation of SNEVhPrp19/hPso4 upon DNA damage or oxidative stress might represent a novel axis capable of modulating cellular life span.
[Show abstract][Hide abstract] ABSTRACT: During the dynamic assembly and activation of the spliceosome, human pre-mRNA processing factor 19 (hPrp19) plays a major role alone or as a part of a protein complex. In addition to participating in post-transcriptional regulation of eukaryotic gene, hPrp19 takes part in many physiological events such as ubiquitin-proteasome system, DNA damage response, proliferation and apoptosis. Increasing evidence also indicates a potential role of hPrp19 during oncogenesis, possibly owing to its activity of repressing apoptosis. Together, these studies add a new dimension to our understanding of hPrp19, and we have reason to believe that continuing excavation of this multi-faceted protein may shed light on its roles in human diseases, especially in cancer.
Biology of the Cell 09/2012; 104(12). DOI:10.1111/boc.201200011 · 3.51 Impact Factor
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