Jin N, Siddiqui R A, English D, Rhoades R A
Department of Physiology/Biophysics, Indiana University School of Medicine, Indianapolis, USA.
Am J Physiol. 1996 Oct;271(4 Pt 2):H1348-55. doi: 10.1152/ajpheart.1996.271.4.H1348.
Two separate signal transduction pathways exist in vascular smooth muscle: one for cell growth, proliferation, and differentiation and the other for contraction. Although activation of protein tyrosine kinases is intimately involved in the signaling pathway that induces cell growth, proliferation, and differentiation, activation of myosin light chain kinase (MLCK) is an important step in the pathway leading to smooth muscle contraction. Indirect evidence suggests that "cross talk" exists between these two signaling pathways, but the common intermediates are not well defined. The purpose of this study was to determine whether a vasoconstrictor and a mitogen initiate crossover signaling between the tyrosine kinase pathway and the MLCK pathway in vascular smooth muscle. Rat aorta and pulmonary arteries were isolated and stimulated with either fetal calf serum (FCS) or phenylephrine in the presence or absence of a tyrosine kinase inhibitor (genistein) or tyrosine phosphatase inhibitor [sodium o-vanadate (Na3 VO4)]. Isometric force was recorded as a function of time; myosin light chain phosphorylation, protein tyrosine phosphorylation, and mitogen-activated protein kinase (MAPK) mobility were determined by immunoblotting. The results demonstrate that FCS, which contains a variety of growth factors known to activate tyrosine kinases, induced myosin light chain phosphorylation and contraction in vascular smooth muscle. Phenylephrine, a vasoconstrictor known to activate MLCK, induced tyrosine phosphorylation of a 42-kDa protein identified as MAPK. Tyrosine phosphorylation of this protein was inhibited by genistein and enhanced by vanadate. Genistein significantly inhibited both serum- and phenylephrine-induced myosin light chain phosphorylation as well as the serum- and phenylephrine-induced force generation, whereas vanadate enhanced these responses. These data demonstrate interrelationship between activation of the tyrosine kinase pathway and the MLCK pathway in vascular smooth muscle. These interactions may influence smooth muscle contraction and be important in the regulation of smooth muscle cell proliferation.
一条用于细胞生长、增殖和分化，另一条用于收缩。虽然蛋白酪氨酸激酶的激活密切参与诱导细胞生长、增殖和分化的信号通路，但肌球蛋白轻链激酶（MLCK）的激活是导致平滑肌收缩通路中的一个重要步骤。间接证据表明这两条信号通路之间存在“串扰”，但共同的中间体尚未明确界定。本研究的目的是确定血管收缩剂和促有丝分裂原是否会在血管平滑肌的酪氨酸激酶途径和MLCK途径之间引发交叉信号传导。分离大鼠主动脉和肺动脉，在存在或不存在酪氨酸激酶抑制剂（染料木黄酮）或酪氨酸磷酸酶抑制剂[偏钒酸钠（Na3VO4）]的情况下，用胎牛血清（FCS）或去氧肾上腺素刺激。记录等长力随时间的变化；通过免疫印迹法测定肌球蛋白轻链磷酸化、蛋白酪氨酸磷酸化和丝裂原活化蛋白激酶（MAPK）迁移率。结果表明，含有多种已知可激活酪氨酸激酶的生长因子的FCS可诱导血管平滑肌中的肌球蛋白轻链磷酸化和收缩。去氧肾上腺素是一种已知可激活MLCK的血管收缩剂，可诱导一种被鉴定为MAPK的42 kDa蛋白的酪氨酸磷酸化。该蛋白的酪氨酸磷酸化被染料木黄酮抑制，被钒酸盐增强。染料木黄酮显著抑制血清和去氧肾上腺素诱导的肌球蛋白轻链磷酸化以及血清和去氧肾上腺素诱导的力产生，而钒酸盐增强了这些反应。这些数据证明了血管平滑肌中酪氨酸激酶途径和MLCK途径激活之间的相互关系。这些相互作用可能影响平滑肌收缩，并在平滑肌细胞增殖的调节中起重要作用。
