Electrical Muscle Activity Pattern and Transcriptional and Posttranscriptional Mechanisms Regulate PKA Subunit Expression in Rat Skeletal Muscle

Author： Hoover F. Kalhovde J.M. Dahle M.K. Skålhegg B. Taskén K. Lømo T.

Publisher： Academic Press

ISSN： 1044-7431

Source： Molecular and Cellular Neuroscience, Vol.19, Iss.2, 2002-02, pp. : 125-137

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Abstract

We have examined protein kinase A (PKA) subunit expression in adult rat skeletal muscles. Northern blots identified PKA catalytic α and regulatory (R) I α and RII α subunits as the major subunits expressed in slowly contracting soleus (SOL) and rapidly contracting extensor digitorum longus (EDL) muscles. In addition, the steady-state RNA levels of PKA subunit mRNAs and activities of RI α and RII α promoters are similar in SOL and EDL. These data indicate that posttranscriptional mechanisms account for the twofold differences in PKA subunit protein levels reported earlier. Electrical stimulation of denervated SOL with an EDL-like activity pattern (fast pattern) transformed SOL into an EDL-like muscle with regard to PKA protein levels. These experiments suggest that the posttranscriptional regulation is activity pattern-dependent. Denervation specifically increased RI α promoter activity and RI α mRNA levels in SOL and EDL. Further experiments indicated that the RI α 1a upstream sequences were activated following denervation. Direct electrical stimulation prevented the rise in RI α mRNA levels following denervation, demonstrating that electrical muscle activity regulates transcription. ©2002 Elsevier Science (USA).