Department of Molecular Medicine, Cornell University, Ithaca, New York 14853-6401, USA.
J Biol Chem. 2011 Oct 28;286(43):37094-107. doi: 10.1074/jbc.M111.242438. Epub 2011 Sep 6.
Cell migration is essential for several important biological outcomes and is involved in various developmental disorders and disease states including cancer cell invasiveness and metastasis. A fundamental step in cell migration is the development of a leading edge. By using HeLa carcinoma cells as an initial model system, we uncovered a surprising role for the heat shock protein 70 (Hsp70) and its ability to bind the protein cross-linking enzyme, tissue transglutaminase (tTG), in cancer cell migration. Treatment of HeLa cells with EGF results in the activation of a plasma membrane-associated pool of tTG and its redistribution to the leading edges of these cells, which are essential events for EGF-stimulated HeLa cell migration. However, we then found that the ability of tTG to be localized to the leading edge is dependent on Hsp70. Similarly, the localization of tTG to the leading edges of MDAMB231 breast carcinoma cells, where it also plays an essential role in their migration, has a strict requirement for Hsp70. Treatment of these different cell lines with inhibitors against the ATP hydrolytic activity of Hsp70 prevented tTG from localizing to their leading edges and thereby blocked EGF-stimulated HeLa cell migration, as well as the constitutive migration normally exhibited by MDAMB231 cells. These findings highlight a new and unconventional role for the chaperonin activity of Hsp70 in the localization of a key regulatory protein (tTG) at the leading edges of cancer cells and the important consequences that this holds for their ability to migrate.
细胞迁移对于许多重要的生物学结果至关重要，并且涉及到各种发育障碍和疾病状态，包括癌细胞的侵袭和转移。细胞迁移的一个基本步骤是形成前缘。通过使用 HeLa 癌细胞作为初始模型系统，我们揭示了热休克蛋白 70（Hsp70）及其与蛋白交联酶组织转谷氨酰胺酶（tTG）结合的能力在癌细胞迁移中的惊人作用。用 EGF 处理 HeLa 细胞会导致与质膜相关的 tTG 池的激活及其重新分布到这些细胞的前缘，这对于 EGF 刺激的 HeLa 细胞迁移是必不可少的事件。然而，我们随后发现 tTG 定位于前缘的能力依赖于 Hsp70。同样，tTG 定位于 MDAMB231 乳腺癌细胞前缘的能力也对其迁移起着至关重要的作用，这对 Hsp70 有严格的要求。用 Hsp70 的 ATP 水解活性抑制剂处理这些不同的细胞系，阻止 tTG 定位于它们的前缘，从而阻止 EGF 刺激的 HeLa 细胞迁移，以及 MDAMB231 细胞通常表现出的组成型迁移。这些发现强调了 Hsp70 伴侣蛋白活性在将关键调节蛋白（tTG）定位在癌细胞前缘中的新的和非常规作用，以及这对它们迁移能力的重要影响。
