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[Effect of Calpain on the Degradation of Tau Protein in Rat Brain Cortex Extracts]

Zheng-Yu Fang, Shi-Jie Liu, Xiao-Chuan Wang, Rong Liu, Qun Wang, Zheng-Yue Chen, Jian-Zhi Wang

Sheng Wu Hua Xue Yu Sheng Wu Wu Li Xue Bao (Shanghai). 2003 Jul;35(7):629-34.

PMID: 12883633

Abstract:

Calpain is a calcium-activated protease and has two ubiquitously distributed mammalian isoforms, namely calpain 1 (calpain I, mu-calpain and CAPN1) and calpain 2 (calpain II, m-calpain and CAPN2). Calpains regulate the function of many proteins by limited proteolysis. To determine the nature of different subtypes of calpain on degradation of microtubule-associated protein tau, the rat cortex extracts were incubated with 0.2 mmol/L, 1 mmol/L, 3 mmol/L and 5 mmol/L of CaCl(2 )for 15 min at 37 degrees C, respectively, and it was found that Ca(2+) treatment at concentrations 1-5 mmol/L led to significant proteolysis of the tau protein and this degradation was blocked by calpain inhibitor, calpeptin. In addition, when the extracts containing 1 mmol/L CaCl(2 )were treated with mu-calpain inhibitor (0.05 micromol/L of calpastatin) or m-calpain inhibitor (100 micromol/L calpain inhibitor IV) or both, the Ca(2+)-induced degradation of tau protein was blocked to about 8.6% 92.5% and 97.8% compared with the group with 1 mmol/L CaCl(2), respectively. These data suggest that both mu-calpain and m-calpain in brain cortex extracts are activated by Ca(2+) and both of them degraded tau protein, although, m-calpain plays a more important role in proteolysis of the tau protein.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
IAR42415257 Calpain Inhibitor IV Calpain Inhibitor IV Price
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