Martin J L, Hickey E, Weber L A, Dillmann W H, Mestril R
Department of Physiology, The Cardiovascular Institute, Loyola University, Chicago, IL, USA.
Gene Expr. 1999;7(4-6):349-55.
Recent reports have demonstrated that the heat shock proteins (hsp) and in particular the hsp70 confer protection against cardiac ischemic damage. More recently, we have shown that increased expression of another heat shock protein, the hsp27, through an adenovirus vector system protects adult cardiomyocytes against ischemic injury. This small heat shock protein undergoes phosphorylation when the cell is under stress. This has led many to speculate that phosphorylation of hsp27 is required for the protective role this protein plays in the cell. In order to investigate this possibility, we have mutated the serines that are the sites of phosphorylation on the hsp27, to glycines or alanines. These nonphosphorylatable mutants of hsp27 were cloned into adenoviral vectors and used to infect adult rat cardiomyocytes to assess their ability in protecting against ischemic injury. In addition, we used a specific inhibitor of p38 MAP kinase that is a key member of the kinase pathway responsible for phosphorylating the hsp27. Our present results show that the nonphosphorylated hsp27 forms larger oligomeric complexes than the phosphorylated hsp27. Interestingly, phosphorylation of hsp27 seems not to play a role in its ability to protect adult rat cardiomyocytes against ischemic damage.
最近的报告表明，热休克蛋白（hsp），尤其是hsp70能对心脏缺血损伤起到保护作用。最近，我们发现通过腺病毒载体系统增加另一种热休克蛋白hsp27的表达，可保护成年心肌细胞免受缺血损伤。当细胞处于应激状态时，这种小分子热休克蛋白会发生磷酸化。这使得许多人推测，hsp27的磷酸化是该蛋白在细胞中发挥保护作用所必需的。为了研究这种可能性，我们将hsp27上作为磷酸化位点的丝氨酸突变为甘氨酸或丙氨酸。将这些不可磷酸化的hsp27突变体克隆到腺病毒载体中，并用于感染成年大鼠心肌细胞，以评估它们抵御缺血损伤的能力。此外，我们使用了一种p38丝裂原活化蛋白激酶的特异性抑制剂，该激酶是负责使hsp27磷酸化的激酶途径的关键成员。我们目前的结果表明，未磷酸化的hsp27比磷酸化的hsp27形成更大的寡聚体复合物。有趣的是，hsp27的磷酸化似乎在其保护成年大鼠心肌细胞免受缺血损伤的能力中不起作用。
