Mehlen P, Arrigo A P
Laboratoire du Stress Cellulaire, CNRS-UMR 106, Université Claude Bernard, France.
Eur J Biochem. 1994 Apr 1;221(1):327-34. doi: 10.1111/j.1432-1033.1994.tb18744.x.
The oligomeric small heat-shock protein hsp27, also denoted hsp28, is constitutively expressed in several mammalian cells and displays a phosphorylation status that is related to cellular growth and differentiation. This protein is related to alpha-crystallin and has strong sequence similarity with an in vitro inhibitor of actin polymerization. Here, we have analyzed hsp27 phosphorylation, cellular localization and structural organization following serum stimulation of serum-starved HeLa cells. hsp27 is dephosphorylated in starved cells and quantitatively recovered in the form of small structures (< 200 kDa) present in the soluble phase of the cytoplasm. Immediately after the addition of serum to starved cells, a rapid phosphorylation and complex changes in the intracellular distribution and structural organization of hsp27 are observed. Phosphorylation essentially occurs at the level of small hsp27 structures (< 200 kDa) and is concomitant with the increased molecular mass (up to 700 kDa) of a fraction of this protein. Serum treatment also induced the detergent-sensitive association of another fraction of hsp27, still in the form of small and dephosphorylated structures, with cellular particulate fractions. Contrasting with these observations, hsp70 had the tendency to concentrate into nucleoli during serum starvation.
寡聚小分子热休克蛋白hsp27，也称为hsp28，在几种哺乳动物细胞中组成性表达，并呈现出与细胞生长和分化相关的磷酸化状态。这种蛋白质与α-晶体蛋白相关，并且与肌动蛋白聚合的一种体外抑制剂具有很强的序列相似性。在这里，我们分析了血清饥饿的HeLa细胞在血清刺激后hsp27的磷酸化、细胞定位和结构组织。hsp27在饥饿细胞中去磷酸化，并以存在于细胞质可溶相中的小结构（<200 kDa）形式定量恢复。向饥饿细胞中添加血清后，立即观察到hsp27的快速磷酸化以及细胞内分布和结构组织的复杂变化。磷酸化主要发生在小的hsp27结构（<200 kDa）水平，并伴随着该蛋白一部分分子量的增加（高达700 kDa）。血清处理还诱导了另一部分hsp27（仍为小的去磷酸化结构形式）与细胞颗粒部分的去污剂敏感结合。与这些观察结果形成对比的是，hsp70在血清饥饿期间倾向于聚集到核仁中。
