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oai:mountainscholar.org:10217/463782025-12-30T03:36:50Zcom_10217_100532com_10217_100000com_10217_100362com_10217_100303col_10217_100538col_10217_100364

Lee, Jerome Edward, author Wilusz, Carol J., advisor Wilusz, Jeffrey, advisor Garrity, Deborah M., committee member Curthoys, Norman P., committee member 2007-01-03T04:58:10Z 2012-09-01T08:10:42Z 2011 Lee_colostate_0053A_10613.pdf http://hdl.handle.net/10217/46378 https://doi.org/10.25675/3.018878 Type I Myotonic Dystrophy (DM1) is characterized by myotonia, cardiac conduction defects, muscle wasting, and insulin resistance. In patient muscle cells expression and function of the RNA-binding proteins CUGBP1 and MBNL1 are disrupted, resulting in altered mRNA metabolism at the levels of splicing and translation. Intriguingly, despite strong evidence for CUGBP1 being a regulator of mRNA turnover in humans and other organisms, the possibility that defects in mRNA decay contribute to DM1 pathogenesis has not been investigated to date. As such, we sought to further characterize the roles of CUGBP1 and its partner, the deadenylase PARN, in mRNA decay in mouse C2C12 muscle cells. The TNF message, which encodes a cytokine known to cause muscle wasting and insulin resistance when over-expressed, was stabilized by depletion of CUGBP1. The normally rapid decay of the TNF mRNA was also disrupted in cells treated with phorbol ester and this coincided with phosphorylation of CUGBP1. These findings provided impetus to undertake a global analysis of mRNA decay rates in muscle cells. Our investigation revealed that GU- and AU-rich sequence elements are enriched in labile transcripts, which encode cell cycle regulators, transcription factors, and RNA-processing proteins. Transcripts specifically bound to CUGBP1 in myoblasts are linked with processes such as mRNA metabolism, protein targeting to the endoplasmic reticulum, cytoskeletal organization, and transcriptional regulation, all of which have implications for muscle cell biology. Consistent with this, CUGBP1 depletion profoundly altered the formation of myotubes during differentiation. Finally we investigated whether PARN, which interacts with CUGBP1 and mediates rapid deadenylation of TNF in HeLa cell extracts, also plays a role in mediating mRNA decay in muscle. We identified 64 mRNA targets whose decay was dependent on PARN. Moreover, deadenylation of the Brf2 mRNA was impaired in PARN knock-down cells supporting that this mRNA is directly and specifically targeted for decay by PARN. Taken together our findings demonstrate that CUGBP1 and PARN are critical regulators of decay for specific sets of transcripts in muscle cells. It seems likely that some or all of the CUGBP1 targets we have identified may be affected in myotonic dystrophy. Defective mRNA turnover could be linked with defects in myogenesis, TNF over-expression, muscle wasting and/or ER stress, all of which have been documented in DM1. born digital doctoral dissertations English eng Colorado State University. Libraries 2000-2019 Copyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright. CELF1 muscle mRNA decay CUGBP1 gene expression PARN Global analysis of mRNA decay rates and RNA-binding specificity reveals novel roles for CUGBP1 and PARN deadenylase in muscle cells Text 2012-09-01 2012-09-01 This Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). Doctor of Philosophy (Ph.D.) Doctoral Cell and Molecular Biology Colorado State University open.access