Proteasome Inhibition in Brain Aging

蛋白酶体存在于大脑的所有细胞中，并介导大部分的整体蛋白质降解。 特别是，蛋白酶体负责介导大脑中大多数氧化和受损蛋白质的降解。蛋白酶体由多个亚基组成，通过至少3种不同的蛋白水解活性的协同作用降解蛋白质。 最近，我们已经确定，有一个大脑区域特异性损伤的糜蛋白酶样活性的蛋白酶体，在正常的大脑老化。 我们实验室最近的研究表明，热休克蛋白（HSP）的表达减少和蛋白酶体亚基的表达减少可能起作用，这可能是年龄相关的蛋白酶体抑制发生的一种机制。 该提案中的数据清楚地表明，蛋白酶体活性的抑制足以诱导氧化DNA在脑中的积累，尽管蛋白酶体抑制在介导脑中氧化应激的年龄相关性增加中的可能作用尚未确定。 该建议的重点是检验以下假设：大脑中HSP、HSP相关蛋白和单个蛋白酶体亚基的表达减少直接导致与年龄相关的蛋白酶体活性受损，而蛋白酶体活性受损直接导致与年龄相关的蛋白质氧化和DNA氧化增加。 检验这一假设的具体目的如下：1）确定衰老脑中蛋白酶体表达的改变2）确定衰老脑中所有蛋白酶体蛋白水解活性的改变3）确定HSP和HSP相关蛋白表达的改变，4）确定蛋白酶体活性在衰老脑中被抑制的机制5）阐明蛋白酶体抑制在衰老脑中的作用，蛋白质氧化和DNA氧化的相关增加。 总之，这些研究将为理解大脑中的蛋白酶体生物学提供基础，并阐明蛋白酶体抑制作为与大脑衰老相关的有害影响的贡献者的参与。

The proteasome is found in all cells of the brain, and mediates the majority of overall protein degradation. In particular, the proteasome is responsible for mediating the degradation of most oxidized and damaged proteins in the brain. The proteasome is composed of multiple subunits, and degrades proteins through the coordinated efforts of at least 3 distinct proteolytic activities. Recently we have identified that there is a brain region specific impairment in the chymotrypsin-like activity of the proteasome, during normal brain aging. Recent studies from our laboratory indicate a possible role for decreased expression of heat shock proteins (HSP), and decreased expression of proteasome subunits, as a possible mechanism by which age-related proteasome inhibition occurs. Data in this proposal clearly demonstrate that inhibition of proteasome activity is sufficient to induce the accumulation of oxidized DNA in the brain, although the possible role of proteasome inhibition in mediating age-related increases in oxidative stress in the brain has not been determined previously. The focus of this proposal is to test the hypothesis that decreased expression of HSP, HSP associated proteins, and individual proteasome subunits in the brain directly contribute to age-related impairment of proteasome activity, which directly contributes to age-related increases in protein oxidation and DNA oxidation. The specific aims for testing this hypothesis are as follows: 1) To determine alterations in proteasome expression in the aging brain 2) To determine alterations in all proteasome proteolytic activities in the aging brain 3) To determine alterations in the expression of HSP, and HSP associated proteins, in the aging brain 4) To determine the mechanism by which proteasome activity is inhibited in the aging brain 5) To elucidate the role of proteasome inhibition in age-related increases in protein oxidation and DNA oxidation. Together, these studies will provide a basis for understanding proteasome biology in the brain, and elucidate the involvement of proteasome inhibition as a contributor to the deleterious effects associated with brain aging.