Frismantiene Agne, Dasen Boris, Pfaff Dennis, Erne Paul, Resink Therese J, Philippova Maria
Department of Biomedicine, Laboratory for Signal Transduction, Basel University Hospital and University of Basel, Basel, Switzerland.
Department of Biomedicine, Laboratory for Signal Transduction, Basel University Hospital and University of Basel, Basel, Switzerland.
Cell Signal. 2016 May;28(5):516-530. doi: 10.1016/j.cellsig.2016.02.014. Epub 2016 Feb 22.
Participation of the cadherin superfamily of adhesion molecules in smooth muscle cell (SMC) phenotype modulation is poorly understood. Immunohistochemical analyses of arterial lesions indirectly suggest upregulated expression of atypical glycosylphosphatidylinositol-anchored T-cadherin on vascular SMCs as a molecular indicator of the dedifferentiated/proliferative phenotype. This study investigated the role of T-cadherin in SMC phenotypic modulation. Morphological, molecular and functional SMC-signature characteristics of rat, porcine and human arterial SMCs stably transduced with respect to T-cadherin upregulation (Tcad+) or T-cadherin-deficiency (shTcad) were compared with their respective control transductants (E-SMCs or shC-SMCs). Tcad+-SMCs displayed several characteristics of the dedifferentiated phenotype including loss of spindle morphology, reduced/disorganized stress fiber formation, decay of SMC-differentiation markers (smooth muscle α-actin, smooth muscle myosin heavy chain, h-caldesmon), gain of SMC-dedifferentiation marker calmodulin, reduced levels of myocardin, nuclear-to-cytoplasmic redistribution of the myocardin related transcription factors MRTFA/B and increased proliferative and migratory capacities. T-cadherin depletion enforced features of the differentiated SMC phenotype. PI3K/Akt is a major signal pathway utilized by T-cadherin in SMCs and we investigated mTORC1/S6K1 and GSK3β axes as mediators of T-cadherin-induced dedifferentiation. Inhibition of mTORC1/S6K1 signalling by rapamycin suppressed proliferation in both E-SMCs and Tcad+-SMCs but failed to restore expression of contractile protein markers in Tcad+-SMCs. Ectopic adenoviral-mediated co-expression of constitutively active GSK3β mutant S9A in Tcad+-SMCs restored the morphological and molecular marker characteristics of differentiated SMCs and normalized rate of proliferation to that in control SMCs. In conclusion our study demonstrates that T-cadherin promotes acquisition of the dedifferentiated phenotype via a mechanism that is dependent on GSK3β inactivation.
黏附分子钙黏蛋白超家族在平滑肌细胞（SMC）表型调节中的作用尚不清楚。对动脉病变的免疫组织化学分析间接表明，血管平滑肌细胞上非典型糖基磷脂酰肌醇锚定的T-钙黏蛋白表达上调，作为去分化/增殖表型的分子指标。本研究调查了T-钙黏蛋白在SMC表型调节中的作用。将大鼠、猪和人动脉平滑肌细胞分别稳定转导上调T-钙黏蛋白（Tcad+）或缺乏T-钙黏蛋白（shTcad），并将其形态、分子和功能上的SMC特征与其各自的对照转导细胞（E-SMCs或shC-SMCs）进行比较。Tcad+-SMC表现出几种去分化表型的特征，包括纺锤形形态丧失、应力纤维形成减少/紊乱、SMC分化标志物（平滑肌α-肌动蛋白、平滑肌肌球蛋白重链、h-钙调蛋白）衰减、SMC去分化标志物钙调蛋白增加、心肌素水平降低、心肌素相关转录因子MRTFA/B的核质重分布以及增殖和迁移能力增加。T-钙黏蛋白缺失强化了分化的SMC表型特征。PI3K/Akt是T-钙黏蛋白在平滑肌细胞中利用的主要信号通路，我们研究了mTORC1/S6K1和GSK3β轴作为T-钙黏蛋白诱导去分化的介质。雷帕霉素抑制mTORC1/S6K1信号传导可抑制E-SMCs和Tcad+-SMCs的增殖，但未能恢复Tcad+-SMCs中收缩蛋白标志物的表达。在Tcad+-SMCs中，异位腺病毒介导的组成型活性GSK3β突变体S9A的共表达恢复了分化的SMC的形态和分子标志物特征，并使增殖率恢复到对照SMC的水平。总之，我们的研究表明T-钙黏蛋白通过依赖于GSK3β失活的机制促进去分化表型的获得。
