MODULATION OF CELLULAR THERMORESISTANCE AND ACTIN FILAMENT STABILITY ACCOMPANIES PHOSPHORYLATION-INDUCED CHANGES IN THE OLIGOMERIC STRUCTURE OF HEAT-SHOCK PROTEIN-27
MODULATION OF CELLULAR THERMORESISTANCE AND ACTIN FILAMENT STABILITY ACCOMPANIES PHOSPHORYLATION-INDUCED CHANGES IN THE OLIGOMERIC STRUCTURE OF HEAT-SHOCK PROTEIN-27
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DOI：
10.1128/mcb.15.1.505
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发表时间：
1995-01-01
影响因子：
5.3
通讯作者：
LANDRY, J
中科院分区：
文献类型：
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作者：
LAVOIE, JN;LAMBERT, H;LANDRY, J
热休克蛋白27（HSP 27）的磷酸化可以调节肌动蛋白丝的动力学响应生长因子。在热休克期间，HSP 27在与促有丝分裂刺激期间相同的位点被相同的蛋白激酶磷酸化。这表明，在生长因子刺激和应激反应期间，蛋白质的相同功能可能被激活。为了确定HSP 27磷酸化在热休克反应中的作用，开发了几种稳定的中国仓鼠细胞系，其组成性表达各种水平的野生型HSP 27（HU27细胞）或人HSP 27的非磷酸化形式（HU27pm3细胞）。与热休克后存活率增加的HU27细胞相反，HU27pm3细胞仅显示出轻微的存活率增加。有证据表明，微丝的稳定是热休克蛋白27的保护功能的一个主要目标。在HU27 pm3细胞中，与对照细胞中的那些相比，微丝被热敏化，而野生型HSP 27引起HU27细胞中这些结构的稳定性增加。与对照细胞相比，HU27而非HU27pm3细胞对细胞松弛素D处理具有高度抗性。此外，在用细胞松弛素D处理的细胞中，野生型HSP 27而不是HSP 27的磷酸化形式加速了肌动蛋白丝的再现。人HSP 27的突变对热休克诱导的蛋白质溶解度和细胞定位的变化没有影响，表明磷酸化不参与这些过程。然而，诱导HSP 27磷酸化应激剂或促分裂剂引起的野生型蛋白质的多聚体大小的减少，这是没有观察到的突变蛋白质的效果。我们建议，早期在应力，磷酸化诱导的构象变化的HSP 27寡聚体调节蛋白质的活性在微丝动力学的水平，从而提高稳定性和加速恢复的细丝。热休克过程中HSP 27提供的保护水平可能因此代表了更好地维持肌动蛋白丝完整性对整体细胞存活的贡献。
Phosphorylation of heat shock protein 27 (HSP27) can modulate actin filament dynamics in response to growth factors. During heat shock, HSP27 is phosphorylated at the same sites and by the same protein kinase as during mitogenic stimulation. This suggests that the same function of the protein may be activated during growth factor stimulation and the stress response. To determine the role of HSP27 phosphorylation in the heat shock response, several stable Chinese hamster cell lines that constitutively express various level of the wild-type HSP27 (HU27 cells) or a nonphosphorylatable form of human HSP27 (HU27pm3 cells) were developed. In contrast to HU27 cells, which showed increased survival after heat shock, HU27pm3 cells showed only slightly enhanced survival. Evidence is presented that stabilization of microfilaments is a major target of the protective function of HSP27. In the HU27pm3 cells, the microfilaments were thermosensitized compared with those in the control cells, whereas wild-type HSP27 caused an increased stability of these structures in HU27 cells. HU27 but not HU27pm3 cells were highly resistant to cytochalasin D treatment compared with control cells. Moreover, in cells treated with cytochalasin D, wild-type HSP27 but not the phosphorylated form of HSP27 accelerated the reappearance of actin filaments. The mutations in human HSP27 had no effect on heat shock-induced change in solubility and cellular localization of the protein, indicating that phosphorylation was not involved in these processes. However, induction of HSP27 phosphorylation by stressing agents or mitogens caused a reduction in the multimeric size of the wild-type protein, an effect which was not observed with the mutant protein. We propose that early during stress, phosphorylation-induced conformational changes in the HSP27 oligomers regulate the activity of the protein at the level of microfilament dynamics, resulting in both enhanced stability and accelerated recovery of the filaments. The level of protection provided by HSP27 during heat shock may thus represent the contribution of better maintenance of actin filament integrity to overall cell survival.