Klucken Jochen, Shin Youngah, Hyman Bradley T, McLean Pamela J
MassGeneral Institute for Neurodegenerative disease, Alzheimer Disease Research Unit, Massachusetts General Hospital, 114 16th Street, Charlestown, MA 02129, USA.
Biochem Biophys Res Commun. 2004 Dec 3;325(1):367-73. doi: 10.1016/j.bbrc.2004.10.037.
alpha-Synuclein aggregation and toxicity play a major role in Parkinson's disease and dementia with Lewy bodies. Hsp70 is a multipurpose stress response chaperone protein that mediates both refolding and degradation of misfolded proteins. We have shown that Hsp70 is able to block both alpha-synuclein toxicity and aggregation. Here we introduce a mutation into the ATPase domain of Hsp70 (K71S) and demonstrate that this abolishes Hsp70 refolding activity. Nonetheless, Hsp70K71S continues to mediate alpha-synuclein degradation and blocks aggregate formation. In contrast to wild type Hsp70, the ATPase domain mutant mediates alpha-synuclein degradation through a non-proteasome inhibitor sensitive pathway. Although Hsp70K71S can diminish levels of alpha-synuclein to an even greater extent than Hsp70, HSP70K71S does not protect against alpha-synuclein toxicity. The Hsp70K71S mutant appears to dissociate the formation of aggregates, which it blocks, and toxicity, which it does not block. These data suggest that the ability of Hsp70 to prevent toxicity is distinct from degradation of alpha-synuclein and is dependent on its ATPase domain.
α-突触核蛋白的聚集和毒性在帕金森病和路易体痴呆中起主要作用。热休克蛋白70（Hsp70）是一种多功能应激反应伴侣蛋白，可介导错误折叠蛋白的重新折叠和降解。我们已经表明，Hsp70能够阻止α-突触核蛋白的毒性和聚集。在此，我们在Hsp70的ATP酶结构域引入一个突变（K71S），并证明这消除了Hsp70的重新折叠活性。尽管如此，Hsp70K71S仍继续介导α-突触核蛋白的降解并阻止聚集体形成。与野生型Hsp70不同，ATP酶结构域突变体通过一条对蛋白酶体抑制剂不敏感的途径介导α-突触核蛋白的降解。虽然Hsp70K71S比Hsp70能更大程度地降低α-突触核蛋白的水平，但HSP70K71S不能预防α-突触核蛋白的毒性。Hsp70K71S突变体似乎使它所阻止的聚集体形成与它未阻止的毒性相分离。这些数据表明，Hsp70预防毒性的能力不同于其对α-突触核蛋白的降解能力，并且依赖于其ATP酶结构域。
