摘要
Calpain是钙依赖性中性蛋白酶 ,根据其对钙敏感性的不同 ,可分为m 和 μ calpain两型 .分别用不同浓度CaCl2 溶液孵育Wistar大鼠脑皮质匀浆液 ,并用蛋白质印迹和定量图像分析技术检测不同亚型calpain对tau蛋白的降解作用 .研究发现 :在 3 7℃用 1mmol/LCa2 + 孵育底物 15min ,可见tau蛋白明显降解 ,并在分子质量为 2 9ku处出现tau蛋白降解片段 ;当Ca2 + 浓度为 5mmol/L时 ,tau蛋白几乎全部被降解 ;这种tau蛋白降解可被calpain特异性抑制剂完全逆转 .进一步的研究发现 ,分别用 μ calpain抑制剂 (0 0 5μmol/Lcalpastatin) ,m calpain抑制剂 (10 0 μmol/LcalpaininhibitorⅣ )或总calpain抑制剂 (552 μmol/Lcalpeptin)与 1mmol/LCa2 + 共同孵育Wistar大鼠脑皮质匀浆液 ,Ca2 + 激活的tau蛋白降解分别被抑制8 6% ,92 5%和 97 8% .结果表明一定浓度的Ca2 + 可同时激活 μ calpain和m calpain ,这两种亚型calpain均参与降解tau蛋白 ,但m calpain的作用比 μ
Calpain is a calcium-activated protease and there are two ubiquitously distributed mammalian calpains, namely calpain 1 (mu-calpain and CAPN1) and calpain 2 (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 brain 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 37degreesC. The findings were that Ca(2+) treatment at concentration 1 similar to 5 mmol/L led to significant proteolysis of 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 mumol/L of calpastatin) or m-calpain inhibitor (100 mumol/L calpain inhibitor IV) or both, the Ca(2+) -induced degradation of tau protein was decreased to 8.6%, 92.5% and 97.8%, respectively. These data suggest that both mu-calpain and m-calpain in brain cortex extracts are activated by Ca(2+) and both of them degrade tau protein, although, m-calpain plays a more important role in proteolysis of tau.
出处
《生物化学与生物物理进展》
SCIE
CAS
CSCD
北大核心
2003年第6期884-888,共5页
Progress In Biochemistry and Biophysics
基金
国家自然科学基金资助项目 ( 3992 50 1 230 1 0 0 2 1 3,30 1 70 2 2 1 ,30 1 0 0 0 57)
国家基础研究发展计划子项目(G1 9990 540 0 7)资助~~
