CASPASE CLEAVAGE OF BRAIN FODRIN

许多神经病理标记物与阿尔茨海默病S病有关 (AD)，其中包括脑底总蛋白(非红系)的增加 SPECTIN)和该蛋白在体内的异常沉积 退化的神经元。Fodrin是一种外周膜蛋白，提供 细胞膜和细胞骨架之间的一个关键环节 神经元。AD中的胡芦巴蛋白沉积与显著的 增加了150 kDa击穿产物(BDP)。BDP中的这一纤维蛋白被认为 由fodrin的α-亚单位的Calain裂解所致，以及 已在阿尔茨海默病患者的大脑中检测到广泛激活的钙蛋白酶。更多 然而，最近，caspase对关键细胞蛋白的切割是 被认为是导致形态和功能变化的原因 当细胞发生凋亡时观察。麦草蛋白的裂解 半胱氨酸氨基转移酶与磷脂酰丝氨酸的暴露直接相关 在细胞表面，也与触发细胞膜有关 流着泪。在Caspase中发现了一个可能的切割位点 α-食物蛋白亚基，位于主要钙蛋白裂解的下游 地点。此外，还产生了针对钙蛋白酶介导的抗体 Fodrin中的裂解位点也识别caspase来源的BDP。这些 令人惊讶的结果加上越来越多的证据表明 细胞凋亡作为AD神经元丢失的机制，提示更多 可能有一种以上的机制参与了胡芦巴中BDP的积累 广告。此外，因为胡芦巴中的BDPs以稳定的形式积累 细胞内沉积，并被两个不同的家族切割 蛋白水解酶代表具有新的抗原表位的死亡产物 提供了钙蛋白和半胱氨酸天冬氨酸酶对 神经退行性疾病。我们建议：1)研究胡芦巴中的BDP 暴露于几种不同的凋亡性损伤和 确定半胱氨酸天冬氨酸酶的裂解位点(S)，Fodrin的α亚基；2) 确定β-半胱氨酸天冬氨酸氨基转移酶的裂解位点 Fodrin的亚单位在细胞凋亡过程中被切割；3)确定是否 仅限于树突的红系形式的Fodrin，有些 以及caspase底物；以及4)形成定点定位的裂解底物 抗Caspase介导的Fodrin BDPs的抗体 上述目标。Fodrin的BDPs清楚地代表了一个独特的特征 阿尔茨海默病发生的神经病理变化和抗体 特别认识到caspase裂解死亡产物应该提供 细胞凋亡在神经退行性变中的作用 疾病。

Many neuropathological markers have been linked to Alzheimer s disease (AD), among them is an increase in total brain fodrin (non-erythroid spectrin) and accumulation of abnormal depositions of this protein in degenerating neurons. Fodrin, a peripheral membrane protein, provides a critical link between the plasma membrane and the cytoskeleton in neurons. The fodrin deposits in AD correlate with a significant increase in 150kDa breakdown product (BDP). This fodrin BDP is believed to result from calpain cleavage of the alpha-subunit of fodrin, and widespread activation of calpain has been detected in AD brains. More recently, however, caspase cleavage of critical cellular proteins is believed to be responsible for the morphological and functional changes observed when cells undergo apoptosis. The cleavage of fodrin by caspases has been directly linked to the exposure of phosphatidylserine on the cell surface, and has also been implicated in triggering membrane blebbing. A putative caspase cleavage site has been identified in the alpha-subunit of fodrin, just downstream of the major calpain cleavage site. Moreover, antibodies developed against the calpain-mediated cleavage site in fodrin also recognize the caspase-derived BDP. These surprising results coupled with increasing evidence implicating apoptosis as the mechanism of neuronal loss in AD, suggest that more than one mechanism may be involved in the accumulation of fodrin BDP in AD. Additionally, because the fodrin BDPs accumulate as stable intracellular deposits and are cleaved by two distinct families of proteases they represent death products with novel antigenic epitopes that provide a signature of the contribution of calpain and caspases to neurodegenerative diseases. We propose to: 1) study the fodrin BDP profiles in neurons exposed to several distinct apoptotic insults and identify the caspase cleavage site(s) the alpha-subunit of fodrin; 2) determine whether the putative caspase cleavage sites in the beta- subunit of fodrin are cleaved during apoptosis; 3) determine if the erythroid forms of fodrin that are restricted to dendrites and some are also caspase substrates; and 4) develop cleavage fodrin site-directed antibodies against the caspase-mediated BDPs of fodrin identified in the above aims. The BDPs of fodrin clearly represent a unique signature of the neuropathological changes that occur in AD, and antibodies that specifically recognize caspase cleavage death products should provide insights into the contribution of apoptosis in neurodegenerative diseases.