Human Mutation in the Anti-apoptotic Heat Shock Protein 20 Abrogates Its Cardioprotective Effects
Human Mutation in the Anti-apoptotic Heat Shock Protein 20 Abrogates Its Cardioprotective Effects
复制标题
DOI：
10.1074/jbc.m802307200
复制
发表时间：
2008-11-28
影响因子：
4.8
通讯作者：
Kranias, Evangelia G.
中科院分区：
文献类型：
--
作者：
Nicolaou, Persoulla;Knoell, Ralph;Kranias, Evangelia G.
小热休克蛋白 Hsp20 可保护心肌细胞免于凋亡，其 Ser(16) 位点的磷酸化可增强其心脏保护作用。为了确定人类 Hsp20 中是否存在可能改变这些有益作用的遗传变异，我们对 1347 名扩张型心肌病患者和 744 名无心脏病受试者的 Hsp20 基因编码区进行了测序。我们在一名患者和三名没有心脏病的人身上发现了人类 Hsp20 基因中的 C59T 替换。所有受试者都是该突变的杂合子，该突变将完全保守的脯氨酸残基在第 20 位 (P20L) 变为亮氨酸，从而导致二级结构改变。为了检查 P20L-Hsp20 人类变体的潜在功能意义，成年大鼠心肌细胞被 Ad 感染。 GFP（其中 Ad 是腺病毒，GFP 是绿色荧光蛋白），Ad。 WT-Hsp20（其中WT是野生型）和Ad.P20L-Hsp20并受到模拟缺血/再灌注损伤。与 GFP 对照相比，WT-Hsp20 的表达导致细胞凋亡显着减弱。然而，通过 Hoechst 染色和 DNA 片段化评估，P20L-Hsp20 突变体没有表现出针对细胞凋亡的保护作用。与 WT-Hsp20 相比，突变型 Hsp20 心脏保护作用的丧失与其 Ser16 磷酸化减弱有关。此外，体外用异丙肾上腺素或蛋白激酶A介导的磷酸化对心肌细胞的最大刺激证实了突变体Hsp20在Ser16处磷酸化的能力受损。总之，我们在人 Hsp20 中发现了 P20L 取代，这与 Ser16 磷酸化的减弱和 Hsp20 心脏保护作用的完全消除有关，这可能对人类携带者应对细胞应激的能力产生不利影响。
The small heat shock protein Hsp20 protects cardiomyocytes against apoptosis, and phosphorylation at its Ser(16) site enhances its cardioprotection. To determine whether genetic variants exist in human Hsp20, which may modify these beneficial effects, we sequenced the coding region of the Hsp20 gene in 1347 patients suffering from dilated cardiomyopathy and 744 subjects with no heart disease. We identified a C59T substitution in the human Hsp20 gene in one patient and three individuals without heart disease. All subjects were heterozygous for this mutation, which changes a fully conserved proline residue into leucine at position 20 (P20L), resulting in secondary structural alterations. To examine the potential functional significance of the P20L-Hsp20 human variant, adult rat cardiomyocytes were infected with Ad. GFP (where Ad is adenovirus and GFP is green fluorescent protein), Ad. WT-Hsp20 (where WT is wild-type), and Ad.P20L-Hsp20 and subjected to simulated ischemia/reperfusion injury. Expression of WT-Hsp20 resulted in significant attenuation of apoptosis compared with the GFP control. However, the P20L-Hsp20 mutant showed no protection against apoptosis, assessed by Hoechst staining and DNA fragmentation. The loss of cardioprotection by the mutant Hsp20 was associated with its diminished phosphorylation at Ser16 compared with WT-Hsp20. Furthermore, maximal stimulation of cardiomyocytes with isoproterenol or protein kinase A-mediated phosphorylation in vitro confirmed the impaired ability of the mutant Hsp20 to become phosphorylated at Ser16. In conclusion, we have identified a P20L substitution in human Hsp20, which is associated with diminished phosphorylation at Ser16 and complete abrogation of the Hsp20 cardioprotective effects which may adversely affect the ability of human carriers to cope with cellular stress.