Identification and Characterization of Protein Phosphatase Methylesterase 1 (Ppme1) in Skeletal Muscle

Abstract

Skeletal muscle atrophy results from a variety of physiological conditions, including immobilization, denervation, glucocorticoid treatment, cancer, and aging. In order to elucidate a better understanding of the molecular and genetic mechanisms of skeletal muscle atrophy, a microarray study was performed using muscle tissue isolated from mice undergoing neurogenic atrophy in response to denervation. The data generated from this microarray identified a suite of several hundred predicted genes that displayed differential expression under conditions of muscle wasting, including protein phosphatase methylesterase 1 (Ppme1). The Ppme1 gene was observed to be transcriptionally upregulated in response to neurogenic skeletal muscle atrophy (i.e. denervation). To confirm that Ppme1 is expressed in muscle, we successfully cloned the predicted Ppme1 cDNA from mouse muscle cells. Additionally, Ppme1 mRNA expression levels were analyzed by quantitative polymerase chain reaction (qPCR) and found to be highly expressed in both proliferating and differentiated muscle cells. Furthermore, Ppme1 protein levels were analyzed by Western blot using protein homogenates isolated from muscle cells and Ppme1 was found to be ubiquitously and uniformly expressed at all time points throughout muscle cell proliferation and differentiation. In order to assess the transcriptional activity of the Ppme1 gene, a fragment of the promoter was cloned, fused to a reporter gene, transfected into C2C12 cells, and found to be transcriptionally active. Additionally, the Ppme1 reporter gene was transfected in combination with MyoD1 and myogenin expression plasmids and differential effects on the Ppme1 reporter gene activity were observed in response to myogenic regulatory factor ectopic expression. The results presented here help contribute new insight into the molecular and genetic mechanisms of muscle atrophy and help provide a better understanding of the genome‐wide transcriptional changes that occur during neurogenic atrophy‐induced muscle wasting.Support or Funding InformationThe work was support by University of North Florida Transformational Learning Opportunity grants to D.W.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.