Upregulation of alpha-skeletal muscle actin and myosin heavy polypeptide gene products in degenerating rotator cuff muscles.
Impaired function of shoulder muscles, resulting from rotator cuff tears, is associated with abnormal deposition of fat in muscle tissue, but corresponding cellular and molecular mechanisms, likely reflected by altered gene expression profiles, are largely unknown. Here, an analysis of muscle gene expression was carried out by semiquantitative RT-PCR in total RNA extracts of supraspinatus biopsies collected from 60 patients prior to shoulder surgery. A significant increase of alpha-skeletal muscle actin (p = 0.0115) and of myosin heavy polypeptide 1 (p = 0.0147) gene transcripts was observed in parallel with progressive fat deposition in the muscle, assessed on parasagittal T1-weighted turbo-spin-echo magnetic resonance images according to Goutallier. Upregulation of alpha-skeletal muscle actin and of myosin heavy polypeptide-1 has been reported to be associated with increased muscle tissue metabolism and oxidative stress. The findings of the present study, therefore, challenge the hypothesis that increased fat deposition in rotator cuff muscle after injury reflects muscle degeneration.
Fuchs
Bruno
B
Laboratory for Orthopedic Research, Balgrist University Hospital, Zurich, Switzerland. research@balgrist.ch <research@balgrist.ch>
Zumstein
Matthias
M
Regenfelder
Felix
F
Steinmann
Patrick
P
Fuchs
Thomas
T
Husmann
Knut
K
Hellermann
Jens
J
Jost
Bernhard
B
Hodler
Jürg
J
Born
Walter
W
Gerber
C
C
D000199:Actins / Q000235:genetics / Q000378:metabolism*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000473:pathology; D050356:Lipid Metabolism / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism*; D017006:Rotator Cuff / Q000378:metabolism / Q000473:pathology; D000070636:Rotator Cuff Injuries; D015854:Up-Regulation
D000199:Actins; D018995:Myosin Heavy Chains