Small molecule inhibitors of calcium-dependent proteases, calpains (CAPNs), protect against neurodegeneration induced by a variety of insults including excitotoxicity and spinal cord injury (SCI). Many of these compounds, however, also inhibit other proteases, which has made it difficult to evaluate the contribution of calpains to neurodegeneration. Calpastatin is a highly specific endogenous inhibitor of classical calpains, including CAPN1 and CAPN2. In the present study, we utilized transgenic mice that overexpress human calpastatin under the prion promoter (PrP-hCAST) to evaluate the hypothesis that calpastatin overexpression protects against excitotoxic hippocampal injury and contusive SCI. The PrP-hCAST organotypic hippocampal slice cultures showed reduced neuronal death and reduced calpain-dependent proteolysis (α-spectrin breakdown production, 145 kDa) at 24 h after N-methyl-D-aspartate (NMDA) injury compared with the wild-type (WT) cultures (n = 5, p < 0.05). The PrP-hCAST mice (n = 13) displayed a significant improvement in locomotor function at one and three weeks after contusive SCI compared with the WT controls (n = 9, p < 0.05). Histological assessment of lesion volume and tissue sparing, performed on the same animals used for behavioral analysis, revealed that calpastatin overexpression resulted in a 30% decrease in lesion volume (p < 0.05) and significant increases in tissue sparing, white matter sparing, and gray matter sparing at four weeks post-injury compared with WT animals. Calpastatin overexpression reduced α-spectrin breakdown by 51% at 24 h post-injury, compared with WT controls (p < 0.05, n = 3/group). These results provide support for the hypothesis that sustained calpain-dependent proteolysis contributes to pathological deficits after excitotoxic injury and traumatic SCI.

中文翻译：

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Calpastatin 过度表达可防止兴奋性海马损伤和创伤性脊髓损伤。

钙依赖性蛋白酶的小分子抑制剂钙蛋白酶 (CAPN) 可防止由多种损伤引起的神经变性，包括兴奋性毒性和脊髓损伤 (SCI)。然而，这些化合物中的许多还抑制其他蛋白酶，这使得评估钙蛋白酶对神经变性的贡献变得困难。Calpastatin 是一种高度特异性的经典钙蛋白酶的内源性抑制剂，包括 CAPN1 和 CAPN2。在本研究中，我们利用在朊病毒启动子 (PrP-hCAST) 下过表达人钙蛋白酶抑制剂的转基因小鼠来评估钙蛋白酶抑制剂过表达可防止兴奋性海马损伤和挫伤性 SCI 的假设。n  = 5，p  < 0.05）。 与 WT 对照相比，PrP-hCAST 小鼠（n = 13）在挫伤性 SCI 后第 1 周和第 3 周显示出运动功能的显着改善（n  = 9，p  < 0.05）。对用于行为分析的相同动物进行的病灶体积和组织保留的组织学评估显示，calpastatin 过度表达导致病灶体积减少 30% ( p  < 0.05)，组织保留、白质保留和灰质显着增加与 WT 动物相比，受伤后 4 周的物质保留。与 WT 对照相比，Calpastatin 过表达使损伤后 24 小时的 α-血影蛋白分解减少了 51%（p  < 0.05，n  = 3/组）。这些结果为持续的钙蛋白酶依赖性蛋白水解导致兴奋性毒性损伤和创伤性 SCI 后病理缺陷的假设提供了支持。