HuR and myogenesis: Being in the right place at the right time

The process of muscle cell differentiation into myotubes, termed myogenesis, depends on a complex coordination of myogenic factors, many of which are regulated post-transcriptionally. HuR, an mRNA-binding protein, is responsible for regulating the expression of several such myogenic factors by stabilizing their mRNAs. The critical role for HuR in myogenesis also involves the nucleocytoplasmic shuttling ability of this protein. Indeed, in order to perform its stabilizing functions, HuR must accumulate in the cytoplasm. This requires its dissociation from the import factor Transportin 2 (TRN2) which is actually caused by the cleavage of a portion of cytoplasmic HuR. In this review, we describe the roles of HuR during myogenesis, and the mechanisms regulating its cytoplasmic accumulation. This article is part of a Special Issue entitled: Regulation of Signaling and Cellular Fate through Modulation of Nuclear Protein Import.

Research highlights
► Post-transcriptional regulation of myogenesis involves RNA-binding proteins such as HuR.
► The cytoplasmic accumulation of HuR is required for its pro-myogenic function.
► Caspase-mediated cleavage of HuR promotes its translocation to the cytoplasm.
► A non-cleavable mutant of HuR acts as a dominant-negative that inhibits myogenesis.