Differential effects of hyperphosphorylation on splicing factor SRp55

Lai, Ming‐Wei; Lin, Ru-Inn; Tarn, Woan‐Yuh

doi:10.1042/bj20021827

Cited by 37 publications

(35 citation statements)

References 43 publications

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“…Previous studies showed that phosphorylation of SR proteins results in either their diffusion in the nucleoplasm (2, 28, 29) or the relocation of SR proteins to speckles (23), which subsequently causes reorganization of nuclear speckles. Thus trafficking of SR proteins with speckles is controlled by mechanisms involved in the phosphorylation process and influences speckled structures.…”

Section: Discussionmentioning

confidence: 99%

“…In addition, increased phosphorylation on SRp30 correlated with NH 2 Cl-induced morphological changes on nuclear speckles. Because the level of phosphorylation controls subnuclear distribution of SR proteins and the reorganization of speckle patterns (2,11,23,28,29), we hypothesized that NH 2 Cl-induced phosphorylation of SRp30 might be associated with NH 2 Cl-triggered aggregation of nuclear speckles in intestinal epithelial cells. In addition, induction of phosphorylation of SRp30 may contribute to oxidant-modulated gene expression in intestinal epithelial cells.…”

Section: Discussionmentioning

confidence: 99%

“…They are dynamic components. When the RS domain is modulated by phosphorylation, SR proteins are redistributed within the nucleus or accumulate in the cytoplasm (11,23). In addition, both hyper-and hypophosphorylation of SR proteins appears to influence protein-protein interactions and to be linked to their physiological functions in vivo (35,38,62).…”

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confidence: 99%

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Monochloramine induces reorganization of nuclear speckles and phosphorylation of SRp30 in human colonic epithelial cells: role of protein kinase C

Zhu¹,

Lu²,

Tan³

2003

American Journal of Physiology-Cell Physiology

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Intestinal epithelial cells are constantly stimulated by reactive oxidant metabolites (ROMs) in inflamed mucosa. Monochloramine (NH2Cl), a cell-permeant ROM, is particularly relevant to the pathogenesis of inflammation in the gastrointestinal tract. Nuclear speckles, a unique nuclear subcompartment, accumulate a family of proteins, namely, serine-and arginine-rich (SR) proteins. They play important roles in regulation of pre-mRNA splicing. Currently, little is known about the link between inflammatory stimulation and the pre-mRNA splicing process, although gene expression is changed in inflamed tissues. The present study was designed to investigate whether stimulation of human colonic epithelial cells (HT-29 and Caco-2 cell lines) with NH2Cl affects nuclear speckles and their components. By indirect immunofluorescence, nuclear speckles have been shown to undergo rapid aggregation after NH2Cl stimulation. By utilizing Western blotting, SRp30 (a subset of SR proteins) in intestinal epithelial cells was found to be phosphorylated after NH2Cl treatment, whereas other SR proteins were not responsive to NH2Cl stimulation. The cytotoxic effect of NH2Cl was excluded by both negative lactate dehydrogenase assay and propidium iodide staining. Therefore, NH2Cl-induced morphological changes on nuclear speckles and phosphorylated SRp30 do not result from intestinal epithelial injury. Furthermore, the effect of NH2Cl on nuclear speckles and SRp30 was blocked by bisindolylmaleimide I, a selective PKC inhibitor. Together, the available data suggest that stimulation of intestinal epithelial cells with NH2Cl results in a consequent change on pre-mRNA splicing machinery via a distinctive signal pathway involving activation of PKC. This effect may contribute to oxidant-induced pathophysiological changes in the gastrointestinal tract.intestinal epithelial cell; reactive oxygen metabolites; premRNA splicing machinery; SR proteins; signal transduction MONOCHLORAMINE (NH 2 CL) is a reactive oxygen metabolite. It is cell membrane permeable because of its high lipophilic property and low molecular weight (55,56).

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Monochloramine induces reorganization of nuclear speckles and phosphorylation of SRp30 in human colonic epithelial cells: role of protein kinase C

Zhu¹,

Lu²,

Tan³

2003

American Journal of Physiology-Cell Physiology

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“…HeLa and HEK-293 cell culture was carried out essentially as we described previously (24). H1299 and A549 cells were cultured in Dulbecco's modified Eagle's medium (DMEM; Gibco), and U2OS cells were cultured in McCoy's 5A medium (Gibco) at 37°C; both media were supplemented with 10% fetal bovine serum (FBS).…”

Section: Methodsmentioning

confidence: 99%

DDX3 Regulates Cell Growth through Translational Control of Cyclin E1

Lai

Chang

Shieh

et al. 2010

Molecular and Cellular Biology

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167

178

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DDX3 belongs to the DEAD box family of RNA helicases, but the details of its biological function remain largely unclear. Here we show that knockdown of DDX3 expression impedes G 1 /S-phase transition of the cell cycle. To know how DDX3 may act in cell cycle control, we screened for cellular mRNA targets of DDX3. Many of the identified DDX3 targets encoded cell cycle regulators, including G 1 /S-specific cyclin E1. DDX3 depletion specifically downregulates translation of cyclin E1 mRNA. Moreover, our data suggest that DDX3 participates in translation initiation of targeted mRNAs as well as in cell growth control via its RNA helicase activity. Consistent with these findings, we show that in the temperature-sensitive DDX3 mutant hamster cell line tsET24, cyclin E1 expression is downregulated at a nonpermissive temperature that inactivates mutant DDX3. Taken together, our results indicate that DDX3 is critical for translation of cyclin E1 mRNA, which provides an alternative mechanism for regulating cyclin E1 expression during the cell cycle.The DEAD box family of RNA helicases plays diverse roles in eukaryotic gene expression, including transcriptional and posttranscriptional regulation (8,40). These helicases contain a highly conserved catalytic core domain that mediates ATP binding, in addition to their ATPase and helicase activities. They are presumed to function in unwinding RNA duplexes or remodeling RNA-protein complexes in an ATP-dependent manner. However, their cellular functions and localization may be defined largely by the divergent sequences flanking the catalytic core domain.Human DDX3 is a DEAD box RNA helicase that participates in various aspects of mRNA metabolism, including translation. The role of DDX3 in translational control is phylogenetically conserved (47). The DDX3 homolog in Saccharomyces cerevisiae, Ded1, participates in translation initiation (6, 9). Analogously, in the fission yeast Schizosaccharomyces pombe, Ded1 is implicated in translational control of two B-type cyclin genes, Cig2 and Cdc13, whose mRNAs contain a complex structure in the 5Ј untranslated region (5Ј UTR) (16). Indeed, Ded1 facilitates efficient RNA duplex unwinding, thus supporting its role in ribosome scanning at the translation initiation step (32). We recently reported that although DDX3 is dispensable for general mRNA translation, it is required for efficient translation of mRNAs that contain a long or structured 5Ј UTR (25). How the biochemical activity of DDX3 contributes to its function, however, remains unclear.In this study, we found that DDX3 targets the mRNA encoding the cell cycle regulator cyclin E1. The eukaryotic cell cycle is driven by a series of cyclin-dependent kinases (Cdks), which are activated via association with their respective cyclin partners (31). Cyclins D and E are specific for cell cycle progression from G 1 to S phase. In early G 1 phase, activated cyclin D-Cdk4/6 phosphorylates the retinoblastoma protein (pRb), which in turn releases E2F from the E2F-pRb complex and stimulates E2F-mediate...

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“…S2). Interestingly, SRp55 hyperphosphorylation relative to other SR proteins has been characterized previously as a unique response to treatment with the transcription inhibitor DRB, but not with other transcription inhibitors, in multiple cell types (Lai et al 2003). Whether DRB treatment might represent a form of stress to the cell analysis of the phosphorylation state of typical SR proteins in response to osmotic stress.…”

Section: Differential Phosphorylation Of Sr Proteins In Sorbitol-treamentioning

confidence: 99%

Regulation of SR protein phosphorylation and alternative splicing by modulating kinetic interactions of SRPK1 with molecular chaperones

Zhong¹,

Ding²,

Adams³

et al. 2009

Genes Dev.

172

189

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Phosphorylation is essential for the SR family of splicing factors/regulators to function in constitutive and regulated pre-mRNA splicing; yet both hypo-and hyperphosphorylation of SR proteins are known to inhibit splicing, indicating that SR protein phosphorylation must be tightly regulated in the cell. However, little is known how SR protein phosphorylation might be regulated during development or in response to specific signaling events. Here, we report that SRPK1, a ubiquitously expressed SR protein-specific kinase, directly binds to the cochaperones Hsp40/DNAjc8 and Aha1, which mediate dynamic interactions of the kinase with the major molecular chaperones Hsp70 and Hsp90 in mammalian cells. Inhibition of the Hsp90 ATPase activity induces dissociation of SRPK1 from the chaperone complexes, which can also be triggered by a stress signal (osmotic shock), resulting in translocation of the kinase from the cytoplasm to the nucleus, differential phosphorylation of SR proteins, and alteration of splice site selection. These findings connect the SRPK to the molecular chaperone system that has been implicated in numerous signal transduction pathways and provide mechanistic insights into complex regulation of SR protein phosphorylation and alternative splicing in response to developmental cues and cellular signaling.[Keywords: SR protein-specific kinase; molecular chaperones; stress signaling; SR protein phosphorylation alternative splicing] Supplemental material is available at http://www.genesdev.org.

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Differential effects of hyperphosphorylation on splicing factor SRp55

Cited by 37 publications

References 43 publications

Monochloramine induces reorganization of nuclear speckles and phosphorylation of SRp30 in human colonic epithelial cells: role of protein kinase C

Monochloramine induces reorganization of nuclear speckles and phosphorylation of SRp30 in human colonic epithelial cells: role of protein kinase C

DDX3 Regulates Cell Growth through Translational Control of Cyclin E1

Regulation of SR protein phosphorylation and alternative splicing by modulating kinetic interactions of SRPK1 with molecular chaperones

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