Husse Britta, Isenberg Gerrit
Julius Bernstein Institute of Physiology, Martin Luther University Halle/Wittenberg, Halle, Germany.
Heart Int. 2010 Jun 23;5(1):e3. doi: 10.4081/hi.2010.e3.
The transcription factor cAMP-response element binding protein (CREB) mediates the mechanical strain-induced gene expression in the heart. This study investigated which signaling pathways are involved in the straininduced CREB activation using cultured ventricular fibroblasts from adult rat hearts. CREB phosphorylation was analyzed by immunocytochemistry and ELISA. Cyclic mechanical strain (1 Hz and 5% elongation) for 15 min induced CREB phosphorylation in all CREB-positive fibroblasts. Several signaling transduction pathways can contribute to strain-induced CREB activation. The inhibition of PKA, PKC, MEK, p38-MAPK or PI3-kinase partially reduced the strain-induced CREB phosphorylation. Activation of PKA by forskolin or PKC by PMA resulted in a level of CREB phosphorylation comparable to the reduced level of the strain-induced CREB phosphorylation in the presence of PKA or PKC inhibitors. Signaling pathways involving PKC, MEK, p38-MAPK or PI3-kinase seem to converge during strain-induced CREB activation. PKA interacted additively with the investigated signaling pathways. The strain-induced c-Fos expression can be reduced by PKC inhibition but not by PKA inhibition. Our results suggest that the complete strain-induced CREB phosphorylation involves several signaling pathways that have a synergistic effect. The influence on gene expression is dependent on the level and the time of CREB stimulation. These wide-ranging possibilities of CREB activation provide a graduated control system.
转录因子环磷酸腺苷反应元件结合蛋白（CREB）介导心脏中机械应变诱导的基因表达。本研究使用成年大鼠心脏培养的心室成纤维细胞，探究了哪些信号通路参与应变诱导的CREB激活。通过免疫细胞化学和酶联免疫吸附测定（ELISA）分析CREB磷酸化。15分钟的周期性机械应变（1赫兹和5%伸长率）可诱导所有CREB阳性成纤维细胞中的CREB磷酸化。几种信号转导通路可能有助于应变诱导的CREB激活。蛋白激酶A（PKA）、蛋白激酶C（PKC）、丝裂原活化蛋白激酶/细胞外信号调节激酶（MEK）、p38丝裂原活化蛋白激酶（p38-MAPK）或磷脂酰肌醇-3激酶（PI3-激酶）的抑制可部分降低应变诱导的CREB磷酸化。福司可林激活PKA或佛波酯激活PKC所导致的CREB磷酸化水平，与存在PKA或PKC抑制剂时应变诱导的CREB磷酸化降低水平相当。涉及PKC、MEK、p38-MAPK或PI3-激酶的信号通路在应变诱导的CREB激活过程中似乎会汇聚。PKA与所研究的信号通路具有累加性相互作用。PKC抑制可降低应变诱导的c-Fos表达，但PKA抑制则不能。我们的结果表明，完整的应变诱导CREB磷酸化涉及多种具有协同作用的信号通路。对基因表达的影响取决于CREB刺激的水平和时间。CREB激活的这些广泛可能性提供了一个分级控制系统。
