Murata Megumi, Miwa Yoko, Sato Iwao
Department of Anatomy, School of Dentistry at Tokyo, Nippon Dental University, 1-9-20 Fujimi Chiyoda-Ku, Tokyo, Japan 102-8159.
Okajimas Folia Anat Jpn. 2009 Nov;86(3):93-103. doi: 10.2535/ofaj.86.93.
The activity of respiratory chain enzymes in a rat's masseter muscle changes as the animal ages; however, there is little information about the RNA transcript levels of mitochondrial enzymes in klotho mutant mice as they age. We measured the activities of NADH-ferricyanide oxidoreductase and NADH-O2 oxidoreductase, and the RNA transcript levels of NADH dehydrogenase, the mitochondrial isoform of ND1, the nuclear isoforms of the 51 kDa and 75 kDa subunits of Complex I, the nuclear isoform of cytochrome c, and the mitochondrial isoform of beta subunits of ATPase (Complex V). In addition, we measured the RNA transcript levels of catalase (CAT) and superoxide dismutase (SOD), which are associated with antioxidant proteins. Moreover, we measured ATP concentrations using a luciferin-luciferase assay, and we determined the amount of cytochrome c associated with mitochondria in both klotho mutant mice and wild-type mice. However, the mRNA levels of cytochrome c and Complex V components, the mRNA levels of CAT, SOD, and apoptosis-inducing factor (Aifm), and the protein level of cytochrome c remained constant as klotho mutant mice aged from 5 weeks to 7 weeks. In wild-type mice, these components (except for those of Complex I) increased over time. NADH-ferricyanide oxidoreductase and NADH-O2 oxidoreductase activities decreased in klotho mutant mice as they aged from 5 weeks to 7 weeks. A few large mitochondria were scattered between myofibrils, and 7-week-old klotho mutant mice displayed an increased number of irregular mitochondria with fewer cristae. Our results indicate that the klotho protein plays a role in the diminished functional adaptability of enzymes in the masseter muscle of klotho mutant mice throughout the aging process.
随着大鼠年龄增长，其咬肌中呼吸链酶的活性会发生变化；然而，关于衰老过程中klotho突变小鼠线粒体酶的RNA转录水平的信息却很少。我们测量了NADH-铁氰化物氧化还原酶和NADH-O2氧化还原酶的活性，以及NADH脱氢酶、ND1的线粒体同工型、复合物I的51 kDa和75 kDa亚基的核同工型、细胞色素c的核同工型以及ATP酶（复合物V）的β亚基的线粒体同工型的RNA转录水平。此外，我们还测量了与抗氧化蛋白相关的过氧化氢酶（CAT）和超氧化物歧化酶（SOD）的RNA转录水平。而且，我们使用荧光素-荧光素酶测定法测量了ATP浓度，并确定了klotho突变小鼠和野生型小鼠中线粒体相关的细胞色素c的量。然而，随着klotho突变小鼠从5周龄到7周龄的衰老，细胞色素c和复合物V成分的mRNA水平、CAT、SOD和凋亡诱导因子（Aifm）的mRNA水平以及细胞色素c的蛋白质水平保持恒定。在野生型小鼠中，这些成分（复合物I的成分除外）随时间增加。随着klotho突变小鼠从5周龄到7周龄的衰老，NADH-铁氰化物氧化还原酶和NADH-O2氧化还原酶的活性降低。一些大的线粒体散布在肌原纤维之间，7周龄的klotho突变小鼠显示出不规则线粒体数量增加，嵴减少。我们的结果表明，klotho蛋白在整个衰老过程中对klotho突变小鼠咬肌中酶的功能适应性下降起作用。
