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.
Department of Human Science, School of Nursing and Health Studies, Georgetown University, 3700 Reservoir Rd., Washington, DC 20057, USA. jkh22@georgetown.edu
Jon-Philippe K
JP
Hyatt
Gary E
GE
McCall
Elizabeth M
EM
Kander
Hui
H
Zhong
Roland R
RR
Roy
Kimberly A
KA
Huey
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