| First Author | Hardee JP | Year | 2018 |
| Journal | Am J Physiol Cell Physiol | Volume | 315 |
| Issue | 1 | Pages | C91-C103 |
| PubMed ID | 29641213 | Mgi Jnum | J:263190 |
| Mgi Id | MGI:6188351 | Doi | 10.1152/ajpcell.00063.2018 |
| Citation | Hardee JP, et al. (2018) Systemic IL-6 regulation of eccentric contraction-induced muscle protein synthesis. Am J Physiol Cell Physiol 315(1):C91-C103 |
| abstractText | Systemic cytokines and contractile activity are established regulators of muscle protein turnover. Paradoxically, the IL-6 cytokine family, which shares the ubiquitously expressed membrane gp130 receptor, has been implicated in skeletal muscle's response to both contractions and cancer-induced wasting. Although we have reported that tumor-derived cachectic factors could suppress stretch-induced protein synthesis in cultured myotubes, the ability of systemic cytokines to disrupt in vivo eccentric contraction-induced protein synthesis has not been established. Therefore, we examined whether systemic IL-6 regulates basal and eccentric contraction-induced protein synthesis through muscle gp130 signaling. Systemic IL-6 overexpression was performed for 2 wk, and we then examined basal and eccentric contraction-induced protein synthesis and mammalian target of rapamycin complex 1 (mTORC1) signaling in tibialis anterior muscle of male wild-type, muscle-specific gp130 receptor knockout, and tumor-bearing Apc(Min/+) mice. Systemic IL-6 overexpression suppressed basal protein synthesis and mTORC1 signaling independently of IL-6 level, which was rescued by muscle gp130 loss. Interestingly, only high systemic IL-6 levels suppressed eccentric contraction-induced protein synthesis. Systemic IL-6 overexpression in precachectic tumor-bearing Apc(Min/+) mice accelerated cachexia development, which coincided with suppressed basal and eccentric contraction-induced muscle protein synthesis. The suppression of eccentric contraction-induced protein synthesis by IL-6 occurred independently of mTORC1 activation. Collectively, these findings demonstrate that basal protein synthesis suppression was more sensitive to circulating IL-6 compared with the induction of protein synthesis by eccentric contraction. However, systemic IL-6 can interact with the cancer environment to suppress eccentric contraction-induced protein synthesis independently of mTORC1 activation. |
