Implication of Akt-dependent Prp19α/14-3-3β/Cdc5L complex formation in neuronal differentiation
ABSTRACT 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.
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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.Aging 04/2012; 4(4):290-304. · 4.89 Impact Factor
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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 · 3.87 Impact Factor
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ABSTRACT: The let-7 microRNA (miRNA) is highly conserved across animal phyla and generally regulates cellular differentiation and developmental timing pathways. In C. elegans, the mature let-7 miRNA starts to accumulate in the last stages of larval development where it directs cellular differentiation programs required for adult fates. Here we show that expression of the let-7 gene in C. elegans is under complex transcriptional control. The onset of let-7 transcription begins as early as the first larval stage in some tissues, and as late as the third larval stage in others, and is abrogated at the gravid adult stage. Transcription from two different start sites in the let-7 promoter oscillates during each larval stage. We show that transcription is regulated by two distinct cis-elements in the promoter of let-7, the previously described temporal regulatory element (TRE), and a novel element downstream of the TRE that we have named the let-7 transcription element (LTE). These elements play distinct and redundant roles in regulating let-7 expression in specific tissues. In the absence of the TRE and LTE, transcription of let-7 is undetectable and worms exhibit the lethal phenotype characteristic of let-7 null mutants. We also identify several genes that affect the transcription of let-7 generally and tissue-specifically. Overall, spatio-temporal regulation of let-7 transcription is orchestrated by multiple cis- and trans-acting factors to ensure appropriate expression of this essential miRNA during worm development.Developmental Biology 11/2012; 374(1). DOI:10.1016/j.ydbio.2012.11.021 · 3.64 Impact Factor