Pervasive satellite cell contribution to uninjured adult muscle fibers.
Pervasive satellite cell contribution to uninjured adult muscle fibers.
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DOI：
10.1186/s13395-015-0067-1
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发表时间：
2015
期刊：
影响因子：
4.9
通讯作者：
Olwin BB
中科院分区：
文献类型：
--
作者：
Pawlikowski B;Pulliam C;Betta ND;Kardon G;Olwin BB
成人骨骼肌适应功能需求，保持一致的肌细胞核和干细胞数量。虽然肌肉生长和修复需要常驻肌肉干细胞或卫星细胞，但在未受伤的肌肉中，这些细胞表现为静止和代谢不活跃。为了研究卫星细胞对成年未受伤骨骼肌中肌纤维的贡献，我们通过在Pax 7 CreER小鼠中诱导LSL-tdTomato重组来标记卫星细胞，并将tdTomato+肌纤维评分作为卫星细胞融合的指标。卫星细胞融合成肌纤维高原出生后8和12周龄之间，达到一个稳定的状态，在后肢肌肉，但在眼外肌或膈肌，卫星细胞融合维持在出生后的水平，无论年龄测定。重组后，在6月龄小鼠中追踪2周后，tdTomato标记的卫星细胞融合到肌纤维中，分别有20%、50%和80%的后肢、眼外和膈肌肌纤维为tdTomato+。卫星细胞在细胞分裂后或直接在没有细胞分裂的情况下形成未损伤的肌纤维。卫星细胞融合成骨骼肌纤维的频率大于先前估计的，这表明卫星细胞融合成成人肌纤维的重要功能作用，并且需要在未受伤的骨骼肌中积极维持卫星细胞数量。
Adult skeletal muscle adapts to functional needs, maintaining consistent numbers of myonuclei and stem cells. Although resident muscle stem cells or satellite cells are required for muscle growth and repair, in uninjured muscle, these cells appear quiescent and metabolically inactive. To investigate the satellite cell contribution to myofibers in adult uninjured skeletal muscle, we labeled satellite cells by inducing a recombination of LSL-tdTomato in Pax7CreER mice and scoring tdTomato+ myofibers as an indicator of satellite cell fusion. Satellite cell fusion into myofibers plateaus postnatally between 8 and 12 weeks of age, reaching a steady state in hindlimb muscles, but in extra ocular or diaphragm muscles, satellite cell fusion is maintained at postnatal levels irrespective of the age assayed. Upon recombination and following a 2-week chase in 6-month-old mice, tdTomato-labeled satellite cells fused into myofibers as 20, 50, and 80 % of hindlimb, extra ocular, and diaphragm myofibers, respectively, were tdTomato+. Satellite cells contribute to uninjured myofibers either following a cell division or directly without an intervening cell division. The frequency of satellite cell fusion into the skeletal muscle fibers is greater than previously estimated, suggesting an important functional role for satellite cell fusion into adult myofibers and a requirement for active maintenance of satellite cell numbers in uninjured skeletal muscle.