Gene Expression Of Hsc70 And Hsp70 In Mammals

热休克基因，包括热休克70基因家族的成员，是高度保守的，一些成员是在环境或生理应激下诱导的。在热休克70家族中，热休克同源基因（hsc70）在非应激脑中的表达水平较高，而在应激脑中的表达水平较高。诱导家族成员（hsp70）在非应激啮齿动物大脑中表达水平非常低，在应激后短暂表达高水平。相比之下，hsp70在所有被检测的人脑中的表达水平要高得多，甚至在那些突然和意外死亡的人身上也是如此，没有记录在案的精神紧张。hsp70的高水平表达可能是人脑的一个特征。另外，死后间隔（PMI）和/或死前应激源都可能影响人脑中hsp70基因家族的表达。在PMI研究中，hsc70和hsp70蛋白在人脑中至少稳定27小时。即使死亡前的压力被消除（医学记录中发现的发烧、缺氧、昏迷等），人类猝死大脑中的hsp70蛋白组成水平仍然比应激的啮齿动物高几倍。这些结果有力地表明hsp70在人脑中的组成表达确实比在啮齿动物脑中高许多倍。非人类灵长类动物的大脑已经被很好地描述了，它的生长和发育与人类大脑相似。使用猴子模型可以消除处理人体组织、死后间隔（PMI）以及死前压力的固有问题。在非人类灵长类动物大脑中，hsc70和hsp70 mRNA水平与人类相似。与人类一样，hsp70蛋白的组成性表达水平很高，仅比hsc70蛋白的表达水平低几倍。hsp70的高表达可能是灵长类动物特有的，也可能与寿命有关。

Heat shock genes, including members of the heat shock 70 gene family, are highly conserved and some members are induced in response to environmental or physiological stress. In the heat shock 70 family, the heat shock cognate (hsc70) gene is expressed at high constitutive levels in non-stressed brain and at higher levels in stressed brain in all species examined so far. Inducible members of the family (hsp70) are expressed at very low levels in non-stressed rodent brain, and transiently expressed at high levels following stress. In contrast, hsp70 is expressed at much higher levels in all human brains assayed, even in persons who died suddenly and unexpectedly, with no documented agonal stress. High levels of expression of hsp70 could be a characteristic of human brain. Alternatively, post mortem interval (PMI), and/or premortem stressors could each be affecting the expression of the hsp70 gene family in human brain. In PMI studies, hsc70 and hsp70 protein was found to be stable for at least 27 hours in human brain. Even when premortem stress was eliminated (fever, hypoxia, coma etc. found in medical records) the constitutive levels of hsp70 protein were still several fold higher in sudden death human brain than that seen in stressed rodent. These results strongly suggest that constitutive expression of hsp70 is indeed many fold higher in human than in rodent brain. The non-human primate brain has been well characterized and its growth and development parallels that seen in human brain. The use of the monkey model would eliminate the inherent problems of working with human tissue, post mortem interval (PMI) as well as premortem stresses. In non-human primate brain, hsc70 and hsp70 mRNA levels were similar to those in humans. As in humans, hsp70 protein was constitutively expressed at high levels, only several fold less than the levels of hsc70 protein. The high hsp70 expression could be primate specific or it could be related to life span.