Muscle mass and area usually decrease with age, and this phenomenon is known as
sarcopenia. This age-related
atrophy correlates with insufficient levels of muscle cells differentiate and proliferate regulated by the TGF-β signaling pathway and the expression of E3s
ubiquitin-protein ligase by the aged.
Sarcopenia makes a huge impact on the aging society, because it has the characteristic of high incidence, extensive adverse effects and disease aggravation gradually. Guided by a
single-guide RNA (sgRNA), Cas9 nuclease has been widely used in genome editing, opening up a new pathway for
sarcopenia treatment. Here, we present two rAAV9 systems, pX601-AAV-CMV:SaCas9-U6:sgRNA and pX601-AAV-EF1α:SaCas9-
tRNAGLN: sgRNA, which edited
myostatin efficiently. By delivering the two rAAV-SaCas9 targets to
myostatin via
intramuscular injection of aged mice, an increase in
body weight and an increase in the number and area of myofibers were observed. Knockout of
myostatin led to TGF-β signaling pathway changes, and increased MyoD, Pax7 and MyoG
protein levels and increased the number of satellite cells to improve muscle cells differentiation. Moreover, knockout of
myostatin prevented the
atrophy of muscle cells through reduced Murf1 and MAFbx
protein levels. We found that both rAAV-SaCas9 systems had gene editing efficiency, reducing the expression of
myostatin by affecting the relevant signaling pathways, thereby altering the physiological status. We showed that
myostatin has an important role in activating skeletal muscle proliferation and inhibiting
muscular atrophy during aging. Thus, we propose that knockout of
myostatin using the rAAV9-SaCas9 system has significant therapeutic potential in
sarcopenia.