Laboratory of Cell Cultures and Cellular Engineering, Institute of Cell Biophysics, Russian Academy of Sciences, 142290, Pushchino, Russia.
Cell Biol Int. 2010 Oct;34(10):985-90. doi: 10.1042/CBI20100147.
The HSPs (heat-shock proteins) of the 70-kDa family, the constitutively expressed HSC70 (cognate 70-kDa heat-shock protein) and the stress-inducible HSP70 (stress-inducible 70-kDa heat-shock protein), have been reported to be actively secreted by various cell types. The mechanisms of the release of these HSPs are obscure, since they possess no consensus secretory signal sequence. We showed that baby hamster kidney (BHK-21) cells released HSP70 and HSC70 in a serum-free medium and that this process was the result of an active secretion of HSPs rather than the non-specific release of the proteins due to cell death. It was found that the secretion of HSP70 and HSC70 is independent of de novo protein synthesis. BFA (Brefeldin A) did not inhibit the basal secretion of HSPs, indicating that the secretion of HSP70 and HSC70 from cells occurs by a non-classical pathway. Exosomes did not contribute to the secretion of HSP70 and HSC70 by cells. MBC (methyl-beta-cyclodextrin), a substance that disrupts the lipid raft organization, considerably reduced the secretion of both HSPs, indicating that lipid rafts are involved in the secretion of HSP70 and HSC70 by BHK-21 cells. The results suggest that HSP70 and HSC70 are actively secreted by BHK-21 cells in a serum-free medium through a non-classical pathway in which lipid rafts play an important role.
热休克蛋白（HSPs）的 70kDa 家族、组成型表达的 HSC70（同源 70kDa 热休克蛋白）和应激诱导的 HSP70（应激诱导的 70kDa 热休克蛋白）已被报道可由各种细胞类型主动分泌。这些 HSPs 的释放机制尚不清楚，因为它们没有保守的分泌信号序列。我们表明，仓鼠肾细胞（BHK-21）在无血清培养基中释放 HSP70 和 HSC70，并且该过程是 HSP 主动分泌的结果，而不是由于细胞死亡导致蛋白质的非特异性释放。发现 HSP70 和 HSC70 的分泌不依赖于新蛋白质的合成。BFA（布雷菲德菌素 A）不抑制 HSP 的基础分泌，表明 HSP70 和 HSC70 从细胞中的分泌是通过非经典途径发生的。外泌体对细胞 HSP70 和 HSC70 的分泌没有贡献。MBC（甲基-β-环糊精），一种破坏脂筏组织的物质，大大减少了两种 HSP 的分泌，表明脂筏参与了 BHK-21 细胞 HSP70 和 HSC70 的分泌。结果表明，HSP70 和 HSC70 通过 BHK-21 细胞在无血清培养基中通过非经典途径主动分泌，脂筏在其中发挥重要作用。
