Massa S M, Longo F M, Zuo J, Wang S, Chen J, Sharp F R
Department of Neurology, University of California, San Francisco, USA.
J Neurosci Res. 1995 Apr 15;40(6):807-19. doi: 10.1002/jnr.490400612.
Following metabolic stress a variety of gene products are induced in cells in the brain, some of which may protect the tissue from subsequent stresses. The heat shock proteins (hsps), in particular hsp70, have been widely studied in this context, but evidence for the involvement of known hsps in protection of the CNS is inconclusive. We have therefore undertaken the search for other stress-induced proteins which may mitigate ischemic injury. Beginning with degenerate RT-PCR, we have isolated a rat-brain cDNA encoding a protein highly similar to human grp75, a mitochondrial member of the hsp70-family of stress proteins. It is also highly similar to two non-mitochondrial proteins; mortalin, a senescence-related gene product, and pbp74, a protein implicated in B-cell peptide processing. Sequence structure and phylogenetic analyses predict mitochondrial localization and induction by a calcium ionophore and glucose deprivation in PC12 cells support its identification as rat grp75. In situ analysis of normal brain reveals an unusual distribution, with very high expression in neurons of the basal forebrain, reticular and subthalamic nuclei, globus pallidus, amygdala and elsewhere. grp75-mRNA is upregulated following focal brain ischemia in a distinctive fashion. When the degree of injury is small, induction occurs in the area of injury, similar to the pattern observed for hsp70. However, when the injury is extensive, hsr is upregulated in neurons outside the ischemic area. The induction of grp75 may represent a sensitive marker of metabolically compromised tissue.
在代谢应激后，大脑中的细胞会诱导产生多种基因产物，其中一些可能会保护组织免受后续应激的影响。热休克蛋白（hsps），特别是hsp70，在这种情况下已被广泛研究，但已知hsps参与中枢神经系统保护的证据尚无定论。因此，我们开始寻找其他可能减轻缺血性损伤的应激诱导蛋白。从简并RT-PCR开始，我们分离出了一种大鼠脑cDNA，它编码的蛋白质与人类grp75高度相似，grp75是应激蛋白hsp70家族的线粒体成员。它也与两种非线粒体蛋白高度相似；mortalin，一种与衰老相关的基因产物，以及pbp74，一种与B细胞肽加工有关的蛋白质。序列结构和系统发育分析预测其定位于线粒体，并且钙离子载体和PC12细胞中的葡萄糖剥夺诱导其表达，这支持将其鉴定为大鼠grp75。对正常大脑的原位分析显示其分布异常，在基底前脑、网状核和丘脑底核、苍白球、杏仁核及其他部位的神经元中表达非常高。局灶性脑缺血后，grp75-mRNA以一种独特的方式上调。当损伤程度较小时，诱导发生在损伤区域，类似于hsp70观察到的模式。然而，当损伤广泛时，hsr在缺血区域外的神经元中上调。grp75的诱导可能代表代谢受损组织的一个敏感标志物。
