Murakami N, Elzinga M
Laboratory of Neurobiochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island 10314.
Cell Motil Cytoskeleton. 1992;22(4):281-95. doi: 10.1002/cm.970220408.
The distribution of nonmuscle myosin isoforms in brain and aorta was studied by using polyclonal antibodies against two synthetic peptides selected from a region near the carboxyl terminus of bovine brain (peptide IIB) and human macrophage (peptide IIA) myosin. Immunoblots of brain homogenates and purified myosin showed two major bands stained by anti-peptide IIB (MIIB1 and MIIB2) and a minor band stained by anti-peptide IIA (MIIA2). Polyclonal anti-human platelet myosin antibodies did not react with MIIB isoforms. In cryosections from bovine, rat, and mouse brains, anti-peptide IIB stained most neuronal cells. In bovine cryosections, glial staining was also observed. In contrast, anti-peptide IIA and anti-platelet myosin antibodies primarily stained blood vessels. In bovine aorta, the anti-peptide antibodies recognized four bands, MIIB3, MIIB4, MIIA1, and MIIA2. Only MIIA2 was recognized by anti-human platelet myosin antibodies. In bovine aorta cryosections, anti-peptide IIB stained smooth muscle cells in tunica intima and tunica media but did not stain endothelial cells. Anti-peptide IIA stained smooth muscle cells in the tunica media, and endothelial cells of vaso vasorum but not of aorta. Only polyclonal anti-platelet myosin antibodies stained the endothelial cells of aorta tunica intima. These results indicate that multiple isoforms of cellular myosins exist in mammals, that these isoforms are expressed in a cell specific manner, and that the major myosin isoforms isolated from whole brain originate from neurons and, at least in bovine brain, from glia, but not from blood vessels.
利用针对从牛脑（肽IIB）和人巨噬细胞（肽IIA）肌球蛋白羧基末端附近区域选择的两种合成肽的多克隆抗体，研究了非肌肉肌球蛋白同工型在脑和主动脉中的分布。脑匀浆和纯化肌球蛋白的免疫印迹显示，抗肽IIB染色有两条主要条带（MIIB1和MIIB2），抗肽IIA染色有一条次要条带（MIIA2）。多克隆抗人血小板肌球蛋白抗体与MIIB同工型无反应。在牛、大鼠和小鼠脑的冰冻切片中，抗肽IIB染色了大多数神经元细胞。在牛的冰冻切片中，也观察到了胶质细胞染色。相比之下，抗肽IIA和抗血小板肌球蛋白抗体主要染色血管。在牛主动脉中，抗肽抗体识别出四条带，即MIIB3、MIIB4、MIIA1和MIIA2。只有MIIA2能被抗人血小板肌球蛋白抗体识别。在牛主动脉冰冻切片中，抗肽IIB染色了内膜和中膜的平滑肌细胞，但未染色内皮细胞。抗肽IIA染色了中膜的平滑肌细胞以及血管滋养管的内皮细胞，但未染色主动脉的内皮细胞。只有多克隆抗血小板肌球蛋白抗体染色了主动脉内膜的内皮细胞。这些结果表明，哺乳动物细胞中存在多种肌球蛋白同工型，这些同工型以细胞特异性方式表达，并且从全脑中分离出的主要肌球蛋白同工型起源于神经元，至少在牛脑中还起源于胶质细胞，而非血管。
