title: Capsaicin mimics mechanical load-induced intracellular signaling events: involvement of TRPV1-mediated calcium signaling in induction of skeletal muscle hypertrophy.
abstract: Mechanical load-induced intracellular signaling events are important for subsequent skeletal muscle hypertrophy. We previously showed that load-induced activation of the cation channel TRPV1 caused an increase in intracellular calcium concentrations ([Ca ( 2+) ]i) and that this activated mammalian target of rapamycin (mTOR) and promoted muscle hypertrophy. However, the link between mechanical load-induced intracellular signaling events, and the TRPV1-mediated increases in [Ca ( 2+) ]i are not fully understood. Here we show that administration of the TRPV1 agonist, capsaicin, induces phosphorylation of mTOR, p70S6K, S6, Erk1/2 and p38 MAPK, but not Akt, AMPK or GSK3β. Furthermore, the TRPV1-induced phosphorylation patterns resembled those induced by mechanical load. Our results continue to highlight the importance of TRPV1-mediated calcium signaling in load-induced intracellular signaling pathways.
authors.affiliation: Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Ito
authors.forename: Urs T
authors.initials: UT
authors.lastname: Ruegg
authors.forename: Akira
authors.initials: A
authors.lastname: Kudo
authors.forename: Yuko
authors.initials: Y
authors.lastname: Miyagoe-Suzuki
authors.forename: Shin'ichi
authors.initials: S
authors.lastname: Takeda
mesh_terms: D000818:Animals; D020013:Calcium Signaling; D008297:Male; D018482:Muscle, Skeletal / Q000473:pathology*; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism*; D030421:Peroxynitrous Acid / Q000378:metabolism*; D050916:TRPV Cation Channels / Q000378:metabolism*
chemical_list: D050916:TRPV Cation Channels; D030421:Peroxynitrous Acid; D052248:Nitric Oxide Synthase Type I
keywords: TRPV1; calcium signaling; capsaicin; mTOR; muscle hypertrophy; skeletal muscle