Proc Natl Acad Sci U S A. 2014 Jun 3. pii: 201406728. [Epub ahead of print]
The endocannabinoid 2-AG controls skeletal muscle cell differentiation via CB1 receptor-dependent inhibition of Kv7 channels.
Iannotti FA1, Silvestri C1, Mazzarella E1, Martella A1, Calvigioni D2, Piscitelli F1, Ambrosino P3, Petrosino S1, Czifra G4, Bíró T4, Harkany T2, Taglialatela M3, Di Marzo V5.
1Endocannabinoid Research Group, Institute of Biomolecular Chemistry, National Council of Research (Consiglio Nazionale delle Ricerche), 80078 Pozzuoli, Italy;
2Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden;Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, A-1090 Vienna, Austria;
3Department of Medicine and Health Sciences, University of Molise, 86100 Campobasso, Italy; and.
4Department of Physiology and Cell Physiology Research Group of the Hungarian Academy of Sciences, University Medical School of Debrecen, 4032, Debrecen, Hungary.
5Endocannabinoid Research Group, Institute of Biomolecular Chemistry, National Council of Research (Consiglio Nazionale delle Ricerche), 80078 Pozzuoli, Italy; vdimarzo@icb.cnr.it.
Little is known of the involvement of endocannabinoids and cannabinoid receptors in skeletal muscle cell differentiation. We report that, due to changes in the expression of genes involved in its metabolism, the levels of the endocannabinoid 2-arachidonoylglycerol (2-AG) are decreased both during myotube formation in vitro from murine C2C12 myoblasts and during mouse muscle growth in vivo. The endocannabinoid, as well as the CB1 agonist arachidonoyl-2-chloroethylamide, prevent myotube formation in a manner antagonized by CB1 knockdown and by CB1 antagonists, which, per se, instead stimulate differentiation. Importantly, 2-AG also inhibits differentiation of primary human satellite cells. Muscle fascicles from CB1 knockout embryos contain more muscle fibers, and postnatal mice show muscle fibers of an increased diameter relative to wild-type littermates. Inhibition of Kv7.4 channel activity, which plays a permissive role in myogenesis and depends on phosphatidylinositol 4,5-bisphosphate (PIP2), underlies the effects of 2-AG. We find that CB1 stimulation reduces both total and Kv7.4-bound PIP2 levels in C2C12 cells and inhibits Kv7.4 currents in transfected CHO cells. We suggest that 2-AG is an endogenous repressor of myoblast differentiation via CB1-mediated inhibition of Kv7.4 channels. |
