J. our results unravel a novel function for Staufen1 in splicing rules and show that it may positively modulate the complex DM1 phenotype, therefore exposing its potential like a therapeutic target. Intro Myotonic dystrophy type 1 (DM1) is definitely caused by an development of CUG repeats located in the 3 untranslated region (3UTR) of dystrophia myotonica protein kinase (DMPK) mRNAs. Pathological severity of DM1 correlates with the number of CUG repeats (Wheeler and Thornton, 2007). This development causes a gain of function of the mutant CUGexp mRNA, which aggregates in the nucleus as ribonuclear foci, sequestering and misregulating transcription factors and RNA-binding proteins normally destined to regulate additional genes and/or mRNAs (Lee and Cooper, 2009). Therefore, the imbalance in cellular regulators induces a harmful GNE0877 cellular effect on the manifestation, rate of metabolism, and/or splicing of target mRNAs, leading to the complex phenotype seen in DM1 (ORourke and Swanson, 2009). In particular, missplicing events can account for symptoms, such as insulin resistance and myotonia, which are linked to aberrant splicing of insulin receptor (IR) and chloride channel (ClC-1) pre-mRNAs, respectively (Ranum and Cooper, 2006). Studies performed with transgenic mouse models support this pathogenicity model. Indeed, mice harboring the human being skeletal actin (HSA) transgene comprising a pathogenic quantity of CTG repeats (250) in the 39UTR, called HSAClong repeat (LR), recapitulate the characteristic features associated with DM1, including nuclear retention of CUGexp mRNAs and aberrant splicing of pre-mRNAs (Mankodi et al., 2000, 2002). Additional transgenic mouse models have more recently confirmed these initial observations (Seznec et al., 2001; Mahadevan et al., 2006; Orengo et al., 2008). In particular, the transgene fused to the 3UTR under the control of a tetracycline-inducible promoter shown inducibility and reversibility of the DM1 pathology (Mahadevan et al., 2006). Given this harmful RNA gain-of-function model, it becomes important to determine proteins that interact with mutant transcripts and that are misregulated in the DM1 pathology. In search of specific proteins that can bind CUG repeats, a few proteins have been characterized, including CUGBP1 (Timchenko et al., 1996) and MBNL1 (Miller et al., 2000), which are both splicing regulators. In DM1, MBNL1 is definitely sequestered in nuclei by CUGexp mRNAs, therefore reducing practical MBNL1 availability in cells (Miller et al., 2000), whereas CUGBP1 manifestation is definitely improved in the cytoplasm (Savkur et al., 2001). In agreement with these observations, mice deficient in MBNL1 (Kanadia et al., 2003) or overexpressing CUGBP1 (Timchenko et al., 2004; Mouse monoclonal to CD45 Ho et al., 2005) display symptoms and splicing abnormalities much like those observed in DM1 individuals, therefore highlighting the complementary functions of misregulated CUGBP1 and MBNL1 in the DM1 pathology. In addition to rules of alternate splicing, these RNA-binding proteins have additional regulatory functions that could also negatively GNE0877 effect DM1, including modulation of translation and RNA stability for CUGBP1 (Timchenko et al., 2001, 2004) and micro-RNA biogenesis for MBNL1 (Rau et al., 2011). Despite the prominent tasks that these two proteins play in DM1, it is reasonable to argue that additional RNA-binding proteins also interact with DMPK transcripts and are abnormally controlled in DM1 skeletal muscle mass. In a earlier study, we characterized the skeletal muscle mass manifestation of the RNA-binding protein Staufen1 (Blanger et al., 2003). Although in the beginning associated with mRNA transport (Kiebler et al., 1999), Staufen1 is now widely recognized like a multifunctional protein involved in key aspects of RNA rate of metabolism. Indeed, we now know that Staufen1 also regulates the translational effectiveness of a human population of mRNAs (Dugr-Brisson et al., 2005) and the stability of transcripts via a mechanism referred to as Staufen-mediated RNA decay (Kim et al., 2005b, 2007). Given its manifestation in skeletal muscle mass (Blanger et al., 2003), its implication in RNA-processing events, and its ability to bind considerable RNA secondary constructions, here, we hypothesize that Staufen1 may consequently be misregulated from the CUG development and that it may participate GNE0877 in the DM1 pathology. In this study, we display that Staufen1 levels are specifically improved in DM1 skeletal muscle mass and establish novel tasks for Staufen1 in pre-mRNA splicing and in the.
