Article

Phosphorylation-Dependent Regulation of PSF by GSK3 Controls CD45 Alternative Splicing

Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, 422 Curie Boulevard, Philadelphia, PA 19104-6059, USA.
Molecular cell (Impact Factor: 14.46). 10/2010; 40(1):126-37. DOI: 10.1016/j.molcel.2010.09.013
Source: PubMed

ABSTRACT Signal-induced alternative splicing of the CD45 gene in human T cells is essential for proper immune function. Skipping of the CD45 variable exons is controlled, in large part, by the recruitment of PSF to the pre-mRNA substrate upon T cell activation; however, the signaling cascade leading to exon exclusion has remained elusive. Here we demonstrate that in resting T cells PSF is directly phosphorylated by GSK3, thus promoting interaction of PSF with TRAP150, which prevents PSF from binding CD45 pre-mRNA. Upon T cell activation, reduced GSK3 activity leads to reduced PSF phosphorylation, releasing PSF from TRAP150 and allowing it to bind CD45 splicing regulatory elements and repress exon inclusion. Our data place two players, GSK3 and TRAP150, in the complex network that regulates CD45 alternative splicing and demonstrate a paradigm for signal transduction from the cell surface to the RNA processing machinery through the multifunctional protein PSF.

1 Follower
 · 
245 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Phosphorylation of peroxisome proliferator-activated receptor γ (PPARγ) at Ser273 by cyclin-dependent kinase 5 (CDK5) in adipose tissue stimulates insulin resistance, but the underlying molecular mechanisms are unclear. We show here that Thrap3 (thyroid hormone receptor-associated protein 3) can directly interact with PPARγ when it is phosphorylated at Ser273, and this interaction controls the diabetic gene programming mediated by the phosphorylation of PPARγ. Knockdown of Thrap3 restores most of the genes dysregulated by CDK5 action on PPARγ in cultured adipocytes. Importantly, reduced expression of Thrap3 in fat tissue by antisense oligonucleotides (ASOs) regulates a specific set of genes, including the key adipokines adiponectin and adipsin, and effectively improves hyperglycemia and insulin resistance in high-fat-fed mice without affecting body weight. These data indicate that Thrap3 plays a crucial role in controlling diabetic gene programming and may provide opportunities for the development of new therapeutics for obesity and type 2 diabetes.
    Genes & Development 10/2014; 28(21). DOI:10.1101/gad.249367.114 · 12.64 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Pre-messenger RNA (mRNA) processing, generally including capping, mRNA splicing, and cleavage-polyadenylation, is physically and functionally associated with transcription. The reciprocal coupling between transcription and mRNA processing ensures the efficient and regulated gene expression and editing. Multiple transcription factors/cofactors and mRNA processing factors are involved in the coupling process. This review focuses on several classic examples and recent advances that enlarge our understanding of how the transcriptional factors or cofactors, especially the Mediator complex, contribute to the RNA Pol II elongation, mRNA splicing, and polyadenylation.For further resources related to this article, please visit the WIREs website.Conflict of interest: The authors have declared no conflicts of interest for this article
    WIREs RNA 12/2014; 6(2). DOI:10.1002/wrna.1273 · 6.15 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The spliceosomal factor TRAP150 is essential for pre-mRNA splicing in vivo and, when overexpressed, it enhances splicing efficiency. In this study, we found that TRAP150 interacted with the cleavage and polyadenylation specificity factor (CPSF) and co-fractionated with CPSF and RNA polymerase II. Moreover, TRAP150 preferentially associated with the U1 small ribonucleoprotein (snRNP). However, our data do not support a role for TRAP150 in alternative 5' splice site or exon selection or in alternative polyadenylation. Because U1 snRNP participates in premature cleavage and polyadenylation (PCPA), we tested whether TRAP150 is a cofactor in the control of PCPA. Although TRAP150 depletion had no significant effect on PCPA, overexpression of TRAP150 forced activation of a cryptic 3' splice site, yielding spliced PCPA transcripts. Mechanistic studies showed that TRAP150-activated splicing occurred in composite but not authentic terminal exons, and such an activity was enhanced by debilitation of U1 snRNP or interference with transcription elongation or termination. Together, these results indicate that TRAP150 provides an additional layer of PCPA regulation, through which it may increase the diversity of abortive RNA transcripts under conditions of compromised gene expression.
    Nucleic Acids Research 10/2014; 42(20). DOI:10.1093/nar/gku963 · 8.81 Impact Factor

Preview

Download
4 Downloads
Available from