ANALYSIS OF FUNCTION OF HUMAN BRAIN CARBOXYPEPTIDASE B-SPECIFIC C14-MODULE

为了阐明人脑羧基肽酶B （HBCPB）的病理生理意义，通过(1)形态学和(2)分子生物化学分析对其特定的c端区域c14模块进行了分析。(1)通过对5例散发性阿尔茨海默病患者与正常老年人的对比分析，得到以下形态学上的新发现。HBCPB在已确定为内质网的神经核周中的表达在整个神经元中进行了分析。在所有正常大脑中，HBCPB在限制性神经元中表达，包括阿尔茨海默病中高度易感的神经元，如海马锥体神经元，也在未参与的神经元中表达，如外侧膝状体神经元。然而，在分析的所有5个阿尔茨海默氏症大脑中，HBCPB在海马锥体神经元中的表达显著降低，而在外侧神经晚期体神经元中则没有。在所有阿尔茨海默病病例中，内质网表达量的选择性减少和表达模式的非均匀性表明，神经元特异性抑制HBCPB表达在阿尔茨海默病的进展中具有病理生理意义。(2)利用抗c14模块抗体对hbcpb - c14模块进行表位分析，明确该模块由EP1和EP2两个表位（各7-氨基酸残基）组成。前者表位高度独立，制备了抗EPI肽的兔抗体（抗C14-EP1）。在HBCPB对合成Aβ1-42的外蛋白水解分析中，EPI肽或抗C14-EP1抗体的共存均抑制了该反应。综上所述，明确了以c14模块为重点的HBCPB功能分析的重要性，并为了解HBCPB作为阿尔茨海默病治疗靶点的意义奠定了坚实的背景。

To clarify a pathophysiological significance of human brain carboxypeptidase B (HBCPB), the specific C-terminal region, C14-moduIe, was analyzed by (1) morphological and (2) molecular-bioc hemical analyses.(1) Through comparative analysis between five cases of sporadic Alzheimer's disease patients and normal aged, the following morphological novel findings were obtained. HBCPB expression in neuronal perikarya, which was already identified as endoplasmic reticulum, was analyzed throughout neurons. In all normal brains, HBCPB is expressed in restricted neurons including highly vulnerable neurons in Alzheimer's disease such as hippocampal pyramidal neuron and also in uninvolved neurons such as lateral geniculate body neurons. In all five Alzheimer's brains analyzed, however, HBCPB expression in hippocampal pyramidal neurons, but not in lateral genicu late body neurons, were significantly decreased. Selective decrease in expressed amount and nonhomogeneous expression pattern in endoplasmic reticulum in all Alzheimer's cases indicate that neuron-specific inhibition of HBCPB expression is of pathophysiological significance in progress ion of Alzheimer's disease.(2) By epitope analysis of HBCPB-C14-module using anti C14-module antibody, it was clarified that the module is composed of two epitopes (each 7- amino' acid residues), EP1 and EP2. The former epitope is highly independent, and an rabbit antibody was raised against EPI peptides (anti C14-EP1). In the exoproteolytic analysis of synthetic Aβ1-42 by HBCPB, both co-existence of EPI peptide or anti C14-EP1 antibody inhibited the reaction.Taken together, it was clarified that functional analysis of HBCPB by focusing on C14-module is important, and a substantial background was establ ished to understand the significance of HBCPB as therapeutical target for Alzheimer's disease.