Yamanaka Kunitoshi, Takahashi Naohiko, Ooie Tatsuhiko, Kaneda Koji, Yoshimatsu Hironobu, Saikawa Tetsunori
Department of Internal Medicine I, School of Medicine, Oita Medical University, 1-1 Idaigaoka, Hasama, 879-5593, Oita, Japan.
J Mol Cell Cardiol. 2003 Jul;35(7):785-94. doi: 10.1016/s0022-2828(03)00133-0.
We recently demonstrated that oral administration of geranylgeranylacetone (GGA), an antiulcer agent, induces heat-shock protein 72 (HSP72) in the rat heart and renders cardioprotection against ischemia/reperfusion injury. However, the signaling pathways remain to be elucidated. The present study tested the hypothesis that oral GGA would activate protein kinase C (PKC), leading to the phosphorylation and translocation of heat-shock factor 1 (HSF1), and thus, promote the expression of HSP72 protein. Rats were classified into four groups: a control (CNT) group (vehicle administration), a GGA group (GGA 200 mg/kg administration), a chelerythrine (CHE)-CNT group (pretreated with intravenous (i.v.) injection of 5 mg/kg CHE before vehicle administration), and a CHE-GGA group (pretreated with CHE before GGA administration). After 24 h administration, oral GGA-induced overexpression of HSP72, increased amount of the phosphorylated form of HSF1 in the nucleus, produced heat-shock element-specific DNA-HSF1 complex, and caused translocation of protein kinase C (PKC)delta, all of which were prevented by pretreatment with CHE. GGA also increased the PKC activity in a particulate fraction, which was prevented by pretreatment with rottlerin, a specific inhibitor of PKCdelta. Isolated-perfused heart experiments revealed that the better functional recovery observed in the GGA group during the reperfusion period following the 20 min of no-flow global ischemia, compared with the CNT group, was abolished by pretreatment with CHE. These results suggest that activation of PKC (translocation of PKCdelta), which primes the phosphorylation of HSF1, plays an essential role in the cardiac overexpression of HSP72 by GGA that leads to cardioprotection.
我们最近证明，口服抗溃疡药物香叶基香叶基丙酮（GGA）可诱导大鼠心脏中的热休克蛋白72（HSP72），并对缺血/再灌注损伤产生心脏保护作用。然而，其信号通路仍有待阐明。本研究检验了以下假设：口服GGA会激活蛋白激酶C（PKC），导致热休克因子1（HSF1）磷酸化和易位，从而促进HSP72蛋白的表达。将大鼠分为四组：对照组（CNT）（给予赋形剂）、GGA组（给予200 mg/kg GGA）、白屈菜红碱（CHE）-CNT组（在给予赋形剂前静脉注射5 mg/kg CHE预处理）和CHE-GGA组（在给予GGA前用CHE预处理）。给药24小时后，口服GGA诱导HSP72过表达，细胞核中HSF1磷酸化形式的量增加，产生热休克元件特异性DNA-HSF1复合物，并导致蛋白激酶C（PKC）δ易位，所有这些均被CHE预处理所阻止。GGA还增加了微粒体部分的PKC活性，这被PKCδ的特异性抑制剂rottlerin预处理所阻止。离体灌注心脏实验显示，与CNT组相比，在20分钟无血流全心缺血后的再灌注期，GGA组观察到的更好的功能恢复被CHE预处理所消除。这些结果表明，PKC的激活（PKCδ的易位）引发HSF1的磷酸化，在GGA诱导的心脏HSP72过表达并导致心脏保护中起重要作用。
