PAX3/7 expression coincides with MyoD during chronic skeletal muscle overload.
Paired box (Pax) proteins 3 and 7 are key determinants for embryonic skeletal muscle development by initiating myogenic regulatory factor (MRF) gene expression. We show that Pax3 and 7 participate in adult skeletal muscle plasticity during the initial responses to chronic overload (< or =7 days) and appear to coordinate MyoD expression, a member of the MRF family of genes. Pax3 and 7 mRNA were higher than control within 12 h after initiation of overload, preceded the increase in MyoD mRNA on day 1, and peaked on day 2. On days 3 and 7, Pax7 mRNA remained higher than control, suggesting that satellite cell self-renewal was occurring. Pax3 and 7 and MyoD protein levels were higher than control on days 2 and 3. These data indicate that Pax3 and 7 coordinate the recapitulation of developmental-like regulatory mechanisms in response to growth-inducing stimuli in adult skeletal muscle, presumably through activation of satellite cells.
Hyatt
Jon-Philippe K
JP
Department of Human Science, School of Nursing and Health Studies, Georgetown University, 3700 Reservoir Rd., Washington, DC 20057, USA. jkh22@georgetown.edu
McCall
Gary E
GE
Kander
Elizabeth M
EM
Zhong
Hui
H
Roy
Roland R
RR
Huey
Kimberly A
KA
D000818:Animals; D015153:Blotting, Western; D001835:Body Weight; D005260:Female; D005786:Gene Expression Regulation; D009124:Muscle Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D017570:MyoD Protein / Q000096:biosynthesis* / Q000235:genetics; D009929:Organ Size; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction
D009124:Muscle Proteins; D017570:MyoD Protein; C057363:MyoD1 myogenic differentiation protein; D000072041:PAX3 Transcription Factor; C530820:PAX3 protein, rat; C530821:PAX7 protein, rat; D051761:Paired Box Transcription Factors; D012333:RNA, Messenger