Equibiaxial strain and strain rate stimulate early activation of G proteins in cardiac fibroblasts
Equibiaxial strain and strain rate stimulate early activation of G proteins in cardiac fibroblasts
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DOI：
10.1152/ajpcell.1998.274.5.c1424
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发表时间：
1998-05-01
影响因子：
5.5
通讯作者：
Frangos, JA
中科院分区：
文献类型：
--
作者：
Gudi, SRP;Lee, AA;Frangos, JA
心脏成纤维细胞负责心脏细胞外基质的产生，成纤维细胞功能的改变与心肌梗死和心脏肥厚有关。本文研究了异三聚体gtp结合蛋白（G蛋白）在大鼠心脏成纤维细胞机械转导中的作用。在等双轴拉伸装置中，细胞与光反应性GTP类似物叠氮analido [α - p -32]GTP （AAGTP）一起孵育，并接受不同方案的应变。放射自显像分析显示，在60秒内，3%菌株暴露12次或6%菌株暴露6次（菌株速率为1.2%/s），细胞标记出42 kda蛋白，而3%菌株暴露6次（菌株速率为0.6%/s），细胞没有可测量的反应。为了进一步研究应变速率对AAGTP结合的影响，我们在10和60 s的时间内分别施加6%的单周期（分别为1.2%和0.2%/s），较快的周期刺激AAGTP结合，而较低的应变速率则没有反应。在单个6%周期/10 s的细胞中，免疫沉淀鉴定aagtp标记的42-kDa带为G蛋白亚基G α (q)和G α (i1)。这些结果表明，G蛋白激活代表了机械应变作用下心脏成纤维细胞的早期机械转导事件之一，应变施加的速率调节了这种反应。
Cardiac fibroblasts are responsible for the production of the extracellular matrix of the heart, with alterations of fibroblast function implicated in myocardial infarction and cardiac hypertrophy. Here the role of heterotrimeric GTP-binding proteins (G proteins) in the mechanotransduction of strain in rat cardiac fibroblasts was investigated. Cells in an equibiaxial stretch device were incubated with the photoreactive GTP analog azidoanalido [alpha-P-32]GTP (AAGTP) and were subjected to various regimens of strain. Autoradiographic analysis showed a 42-kDa protein labeled for cells exposed to 12 cycles of 3% strain or 6 cycles of 6% strain over 60 s (strain rate of 1.2%/s), whereas 6 cycles of 3% strain (0.6%/s) elicited no measurable response. To further investigate the role of strain rate, a single 6% cycle over 10 or 60 s (1.2% and 0.2%/s, respectively) was applied, with the more rapid cycle stimulating AAGTP binding, whereas the lower strain rate showed no response. In cells subjected to a single 6% cycle/10 s, immunoprecipitation identified the AAGTP-labeled 42-kDa band as the G protein subunits G alpha(q) and G alpha(i1). These results demonstrate that G protein activation represents one of the early mechanotransduction events in cardiac fibroblasts subjected to mechanical strain, with the rate at which the strain is applied modulating this response.