Chinni C, de Niese M R, Jenkins A L, Pike R N, Bottomley S P, Mackie E J
School of Veterinary Science, University of Melbourne, Parkville, Victoria 3010, Australia.
J Cell Sci. 2000 Dec;113 Pt 24:4427-33. doi: 10.1242/jcs.113.24.4427.
Protease-activated receptor-2 (PAR-2) is a G protein-coupled receptor that is cleaved by proteases within the N terminus, exposing a new tethered ligand that binds and activates the receptor. Activators of PAR-2 include trypsin and mast cell tryptase. Skeletal myoblasts are known to express PAR-1, a thrombin receptor. The current study was undertaken to determine whether myoblasts express PAR-2. Primary neonatal rat and mouse skeletal myoblast cultures were shown to express PAR-2 in polymerase chain reaction and immunocytochemical studies. Expression of PAR-2 was also demonstrated by immunohistochemistry in developing mouse skeletal muscle in vivo. Trypsin or a synthetic peptide corresponding to the rat PAR-2 tethered ligand caused a dose-dependent elevation in intracellular calcium in cultured rat myoblasts, with an EC(50) of 13 nM or 56 microM, respectively. Studies aimed at identifying the function of PAR-2 in myoblasts demonstrated no effect of the receptor-activating peptide on survival or fusion in serum-deprived myoblasts. The PAR-2-activating peptide did, however, stimulate proliferation of serum-deprived myoblasts. These results demonstrate that skeletal muscle cells express PAR-2, activation of which leads to stimulation of myoblast proliferation.
蛋白酶激活受体-2（PAR-2）是一种G蛋白偶联受体，其N端被蛋白酶切割，暴露出一种新的拴系配体，该配体结合并激活该受体。PAR-2的激活剂包括胰蛋白酶和肥大细胞类胰蛋白酶。已知骨骼肌成肌细胞表达PAR-1，一种凝血酶受体。当前的研究旨在确定成肌细胞是否表达PAR-2。在聚合酶链反应和免疫细胞化学研究中，原代新生大鼠和小鼠骨骼肌成肌细胞培养物显示表达PAR-2。PAR-2的表达在体内发育中的小鼠骨骼肌的免疫组织化学中也得到了证实。胰蛋白酶或与大鼠PAR-2拴系配体相对应的合成肽在培养的大鼠成肌细胞中引起细胞内钙浓度的剂量依赖性升高，其半数有效浓度（EC50）分别为13 nM或56 μM。旨在确定PAR-2在成肌细胞中功能的研究表明，受体激活肽对血清饥饿的成肌细胞的存活或融合没有影响。然而，PAR-2激活肽确实刺激了血清饥饿的成肌细胞的增殖。这些结果表明骨骼肌细胞表达PAR-2，其激活导致成肌细胞增殖的刺激。
