Premium
Nitric Oxide Mediates Stretch‐Induced Proliferation in Myoblasts
Author(s) -
Soltow Quinlyn A.,
Lira Vitor A.,
Betters Jenna L.,
Gutierrez Bryan J.,
Long H. Jodi,
Criswell David S.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.lb33-a
Subject(s) - myocyte , nitric oxide synthase , dapi , nitric oxide , chemistry , c2c12 , cell growth , microbiology and biotechnology , endocrinology , biology , biochemistry , myogenesis , apoptosis
PURPOSE Cyclo‐oxygenase (COX) activity and the transcription factor NFκB are important for satellite cell proliferation and differentiation. Since transcription of both COX‐2 and nitric oxide synthase (NOS) can be regulated by NFκB, we sought to determine if NOS, COX‐2, and NFκB activity are necessary for basal and stretch‐induced myoblast proliferation. METHODS C2C12 myoblasts were cultured in growth medium (10% FBS) for 24h, then switched to differentiation medium for 24h (2%HoS) containing either the NOS inhibitor L‐NAME (200μM), the COX‐2 specific inhibitor NS‐398 (100μM), the NFkB inhibitor PDTC (5mM), or no supplement (control). Subgroups of control, L‐NAME, and PDTC cultures were exposed to 1h of 15% cyclic stretch (1 Hz), and were then allowed to proliferate for 24h before fixing. Proliferation was measured by BrdU incorporation during the last hour before fixing, and DAPI stain. Separately, cultured L6 myoblasts were exposed to the NO‐donor, SNAP (100, 500, 1000, 5000μM) in media (2%HoS) for 16h. RESULTS Stretch induced a two‐fold increase in nuclear number compared to control, and this effect was completely inhibited by L‐NAME and PDTC (P<0.05). Basal proliferation was reduced ~35% and ~50% by NS‐398 and PDTC, respectively (P<0.05). SNAP (500 and 1000μM) induced a 2.0–2.5‐fold increase in COX‐2 mRNA expression (P<0.05). CONCLUSIONS Nitric oxide (NO) and NFκB are necessary for stretch‐induced proliferation of myoblasts. COX‐2 and NFκB are both involved in basal proliferation, and NO can induce COX‐2 expression in myoblasts. Therefore, we propose that NO induction of COX‐2 in muscle is likely mediated by NFκB and is critical for proliferation in response to cyclic stretch. Supported by the University of Florida Opportunity Fund.