Poly c binding protein 2 mediated post transcriptional regulation of utrophin a expression in c2c12 cells

Abstract

Duchenne Muscular Dystrophy (DMD) is an X-linked neuromuscular disorder affecting 1 in every 3500 males worldwide. Mutations in Dystrophin gene cause DMD disease. Dystrophin is the key component of Dystrophin Associated Protein Complex (DAPC) that helps in stabilizing sarcolemmal integrity. Although many therapeutic approaches have been tried such as cell-based therapy, gene therapy, exon-skipping, etc. but nothing has been successfully established as DMD treatment. Glucocorticoid based drugs with physical therapy is the only available treatment till date. Utrophin, the autosomal homologue of dystrophin may replace dystrophin in DAPC complex to compensate dystrophin deficiency. Utrophin has been reported to compensate dystrophin deficiency in mdx mice model. Thus, over-expression of utrophin can eliminate or ameliorate disease phenotype of DMD. Therefore, utrophin upregulation can be a therapeutic approach to treat DMD phenotype. In order to achieve utrophin upregulation in myofibre, understanding of regulatory mechanisms of utrophin expression is required. So far, transcriptional regulation of utrophin expression has been investigated in detail. However, utrophin-A mRNA UTRs play an important role in repression of utrophin expression in mouse myoblast C2C12 cells. Till date no transacting factor has been reported that contributes in 5 UTR mediated repression of utrophin-A expression. Poly (C) binding protein 2 (Pcbp2) is a member of sequence specific RNA binding protein with three evolutionary conserved KH domains. These domains are responsible for their C-rich sequence binding in single stranded nucleic acids. Pcbps are attributed with various cellular functions such as mRNA stability, transcriptional repression and enhancement, translational repression and activation, induction of programmed cell death etc. Initial bioinformatics study shows utrophin-A 5 UTR has poly C stretches that may bind to Pcbp2.