Phosphatidylserine (PS) is distributed asymmetrically in the plasma membrane of eukaryotic cells. Phosphatidylserine flippase (P4-ATPase) transports PS from the outer leaflet of the lipid bilayer to the inner leaflet of the membrane to maintain PS asymmetry. The β subunit TMEM30A is indispensable for transport and proper function of P4-ATPase. Previous studies have shown that the ATP11A and TMEM30A complex is the molecular switch for myotube formation. However, the role of Tmem30a in skeletal muscle regeneration remains elusive. In the current study, Tmem30a was highly expressed in the tibialis anterior (TA) muscles of dystrophin-null ( mdx) mice and BaCl 2-induced muscle injury model mice. We generated a satellite cell (SC)-specific Tmem30a conditional knockout (cKO) mouse model to investigate the role of Tmem30a in skeletal muscle regeneration. The regenerative ability of cKO mice was evaluated by analyzing the number and diameter of regenerated SCs after the TA muscles were injured by BaCl 2-injection. Compared to the control mice, the cKO mice showed decreased Pax7 + and MYH3 + SCs, indicating diminished SC proliferation, and decreased expression of muscular regulatory factors (MYOD and MYOG), suggesting impaired myoblast proliferation in skeletal muscle regeneration. Taken together, these results demonstrate the essential role of Tmem30a in skeletal muscle regeneration.
真核细胞质膜中的磷脂酰丝氨酸（PS）是不对称分布的。磷脂酰丝氨酸翻转酶（flippase）能将PS从质膜双分子层的外叶转移到膜的内叶，维持PS的不对称分布。Flippase的β亚基TMEM30A决定其正确的细胞定位及细胞功能。先前研究报道ATP11A和TMEM30A复合物是控制肌管形成的分子开关，然而 Tmem30a在骨骼肌再生过程中的作用尚不明确。在该研究中，我们发现 Tmem30a在肌肉营养不良小鼠和BaCl 2诱导骨骼肌损伤模型小鼠的胫骨前肌中都有高表达。进一步我们构建了在卫星细胞中特异性敲除 Tmem30a的小鼠模型来研究 Tmem30a在骨骼肌再生过程中的作用。通过H&E和天狼星红染色，分析BaCl 2损伤骨骼肌后再生卫星细胞的数量和直径，发现敲除小鼠的骨骼肌再生被延迟。紧接着通过免疫组织化学实验发现，条件性敲除小鼠的再生骨骼肌区域中Pax7阳性和MYH3阳性的卫星细胞数量减少，表明卫星细胞增殖受到一定的影响。随后发现在敲除小鼠的再生骨骼肌区域中肌肉调节因子(MYOD和MYOG)表达也减少，表明骨骼肌再生中成肌细胞的增殖受损。综上所述，这些结果证明 Tmem30a在骨骼肌再生过程中发挥着重要作用。.
Keywords: Atp11a; Knockout mouse model; Satellite cell; Skeletal muscle regeneration; Tmem30a.