Division of Geriatric Medicine & Gerontology, Department of Internal Medicine, Mayo Clinic, Rochester, MN 55905.
Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905.
Proc Natl Acad Sci U S A. 2022 Jun 14;119(24):e2103615119. doi: 10.1073/pnas.2103615119. Epub 2022 Jun 7.
Skeletal muscle atrophy is commonly associated with aging, immobilization, muscle unloading, and congenital myopathies. Generation of mature muscle cells from skeletal muscle satellite cells (SCs) is pivotal in repairing muscle tissue. Exercise therapy promotes muscle hypertrophy and strength. Primary cilium is implicated as the mechanical sensor in some mammalian cells, but its role in skeletal muscle cells remains vague. To determine mechanical sensors for exercise-induced muscle hypertrophy, we established three SC-specific cilium dysfunctional mouse models- () () ()- (), and -by specifically deleting a ciliary protein ARL3 in MYF5-expressing SCs, or IFT88 in PAX7-expressing SCs, or ARL3 in PAX7-expressing SCs, respectively. We show that the mice develop grossly the same as WT mice. Intriguingly, mechanical stimulation-induced muscle hypertrophy or myoblast differentiation is abrogated in and mice or primary isolated and myoblasts, likely due to defective cilia-mediated Hedgehog (Hh) signaling. Collectively, we demonstrate SC cilia serve as mechanical sensors and promote exercise-induced muscle hypertrophy via Hh signaling pathway.
骨骼肌萎缩通常与衰老、固定、肌肉失用和先天性肌病有关。从骨骼肌卫星细胞 (SCs) 生成成熟的肌肉细胞对于修复肌肉组织至关重要。运动疗法可促进肌肉肥大和力量增加。初级纤毛被认为是某些哺乳动物细胞中的机械感受器,但它在骨骼肌细胞中的作用尚不清楚。为了确定运动引起的肌肉肥大的机械感受器,我们建立了三个 SC 特异性纤毛功能障碍的小鼠模型- () () ()- (), 和 -通过分别在 MYF5 表达的 SC 中特异性删除纤毛蛋白 ARL3、在 PAX7 表达的 SC 中特异性删除 IFT88 或在 PAX7 表达的 SC 中特异性删除 ARL3。我们表明,与 WT 小鼠相比, 小鼠大体上发育正常。有趣的是,机械刺激诱导的肌肉肥大或成肌细胞分化在 和 小鼠或原代分离的 和 成肌细胞中被阻断,这可能是由于纤毛介导的 Hedgehog (Hh) 信号通路缺陷所致。总之,我们证明 SC 纤毛作为机械感受器,并通过 Hh 信号通路促进运动引起的肌肉肥大。