Activation of mTORC1 in skeletal muscle regulates whole-body metabolism through FGF21.
Sci Signal
; 8(402): ra113, 2015 Nov 10.
Article
en En
| MEDLINE
| ID: mdl-26554817
ABSTRACT
Skeletal muscle is the largest organ, comprising 40% of the total body lean mass, and affects whole-body metabolism in multiple ways. We investigated the signaling pathways involved in this process using TSCmKO mice, which have a skeletal muscle-specific depletion of TSC1 (tuberous sclerosis complex 1). This deficiency results in the constitutive activation of mammalian target of rapamycin complex 1 (mTORC1), which enhances cell growth by promoting protein synthesis. TSCmKO mice were lean, with increased insulin sensitivity, as well as changes in white and brown adipose tissue and liver indicative of increased fatty acid oxidation. These differences were due to increased plasma concentrations of fibroblast growth factor 21 (FGF21), a hormone that stimulates glucose uptake and fatty acid oxidation. The skeletal muscle of TSCmKO mice released FGF21 because of mTORC1-triggered endoplasmic reticulum (ER) stress and activation of a pathway involving PERK (protein kinase RNA-like ER kinase), eIF2α (eukaryotic translation initiation factor 2α), and ATF4 (activating transcription factor 4). Treatment of TSCmKO mice with a chemical chaperone that alleviates ER stress reduced FGF21 production in muscle and increased body weight. Moreover, injection of function-blocking antibodies directed against FGF21 largely normalized the metabolic phenotype of the mice. Thus, sustained activation of mTORC1 signaling in skeletal muscle regulated whole-body metabolism through the induction of FGF21, which, over the long term, caused severe lipodystrophy.
Texto completo:
1
Bases de datos:
MEDLINE
Asunto principal:
Músculo Esquelético
/
Complejos Multiproteicos
/
Serina-Treonina Quinasas TOR
/
Factores de Crecimiento de Fibroblastos
Tipo de estudio:
Etiology_studies
Límite:
Animals
Idioma:
En
Revista:
Sci Signal
Asunto de la revista:
CIENCIA
/
FISIOLOGIA
Año:
2015
Tipo del documento:
Article
País de afiliación:
Suiza