A novel GFP reporter mouse reveals Mustn1 expression in adult regenerating skeletal muscle, activated satellite cells and differentiating myoblasts Journal Articles uri icon

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  • AbstractAimMustn1 has been implicated in myofusion as well as skeletal muscle growth and repair; however, the exact role and spatio‐temporal expression of Mustn1 have yet to be fully defined.MethodsTransgenic mice were generated with a 1512‐bp sequence of the Mustn1 promoter directing the expression of GFP (Mustn1PROGFP). These mice were used to investigate the spatio‐temporal expression of Mustn1PROGFP during skeletal muscle development and adult skeletal muscle repair, as well as various phases of the satellite cell lifespan (i.e. quiescence, activation, proliferation, differentiation).ResultsMustn1PROGFP expression was observed within somites at embryonic day 12 and developing skeletal muscles at embryonic day 15 and 18. While uninjured adult tibialis anterior muscle displayed no detectable Mustn1PROGFP expression, cardiotoxin injury robustly elevated Mustn1PROGFP expression at 3 days post‐injury with decreasing levels observed at 5 days and minimal, focal expression seen at 10 days. The expression of Mustn1PROGFP at 3 days post‐injury consistently overlaid with MyoD although the strongest expression of Mustn1PROGFP was noted in newly formed myotubes that were expressing minimal levels of MyoD. By 5 days post‐injury, Mustn1PROGFP overlaid in all myotubes expressing myogenin although cells were present expressing Mustn1PROGFP alone. The expression patterns of Mustn1PROGFP in regenerating muscle preceded the expression of desmin throughout the regenerative time course consistent with Mustn1 being upstream of this myogenic protein. Further, quiescent satellite cells located on freshly isolated, single myofibers rarely expressed Mustn1PROGFP, but within 24 h of isolation, all activated satellite cells expressed Mustn1PROGFP. Expression of Mustn1PROGFP in primary myoblasts diminished with prolonged time in proliferation media. However, in response to serum withdrawal, the expression of Mustn1PROGFP increased during myofusion (day 2) followed by declining expression thereafter.ConclusionMustn1PROGFP is expressed in activated satellite cells and myoblasts but continued time in proliferation media diminished Mustn1PROGFP expression. However, myoblasts exposed to serum withdrawal increased Mustn1PROGFP expression consistent with its demonstrated role in myofusion. The in vivo expression pattern of Mustn1 observed in regenerating and developing skeletal muscle is consistent with its presence in satellite cells and its critical role in myofusion.


  • Krause, MP
  • Moradi, J
  • Coleman, SK
  • D'Souza, DM
  • Liu, C
  • Kronenberg, MS
  • Rowe, DW
  • Hawke, Thomas
  • Hadjiargyrou, M

publication date

  • June 2013

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