Zinc finger protein 593 is upregulated during skeletal muscle atrophy and modulates muscle cell differentiation

Skeletal muscle atrophy is a debilitating condition that can arise due to aging, cancer, corticosteroid use, and denervation. To better characterize the molecular genetic events of neurogenic atrophy, a previous study analyzed gene expression patterns in gastrocnemius muscle following sciatic nerve transection and found for the first time that Zinc Finger Protein 593 (Zfp593) is expressed in skeletal muscle and is induced in response to denervation. Quantitative PCR and Western blot analyses confirmed that Zfp593 is expressed in both proliferating myoblasts and differentiated myotubes. To assess sub-cellular location, GFP-tagged Zfp593 was expressed in C₂C₁₂ cells and found to localize to the nucleus. The Zfp593 protein possesses a putative zinc finger domain and is believed to function as a modulator of the Oct-2 transcription factor. Interestingly, ectopic expression of Zfp593 did not affect the ability of Oct-1 or Oct-2 to inhibit an Oct reporter gene in muscle cells. Finally, Zfp593 overexpression in cultured muscle cells resulted in significant repression of muscle cell differentiation and attenuation of ERK1/2 and p38 phosphorylation, but did not vitiate protein synthesis. The discovery that Zfp593 is expressed in skeletal muscle combined with the observation that it is induced in response to neurogenic atrophy furthers our understanding of the molecular genetic events of muscle wasting.