Majaw T, Sharma R
Department of Biochemistry, North-Eastern Hill University, Shillong 793 022, India.
J Biosci. 2017 Jun;42(2):275-283. doi: 10.1007/s12038-017-9683-8.
Arginase II is a mitochondrial enzyme that catalyses the hydrolysis of L-arginine into urea and ornithine. It is present in other extra-hepatic tissues that lack urea cycle. Therefore, it is plausible that arginase II has a physiological role other than urea cycle which includes polyamine, proline, glutamate synthesis and regulation of nitric oxide production. The high expression of arginase II in kidney, among extrahepatic tissues, might have an important role associated with kidney functions. The present study is aimed to determine the age-associated alteration in the activity and expression of arginase II in the kidney of mice of different ages. The effect of dietary restriction to modulate the agedependent changes of arginase II was also studied. Results showed that renal arginase II activity declines significantly with the progression of age (p less than 0.01 and p less than 0.001 in 6- and 18-month-old mice, respectively as compared to 2-month old mice) and is due to the reduction in its protein as well as the mRNA level (p less than 0.001 in both 6- and 18-month-old mice as compared to 2-month-old mice). Long-term dietary restriction for three months has significantly up-regulated arginase II activity and expression level in both 2- and 18-month-old mice (p less than 0.01 and p less than 0.001, respectively as compared to AL group). These findings clearly indicate that the reducing level of arginase II during aging might have an impact on the declining renal functions. This age-dependent down-regulation of arginase II in the kidney can be attenuated by dietary restriction which may help in the maintenance of such functions.
精氨酸酶II是一种线粒体酶，可催化L-精氨酸水解为尿素和鸟氨酸。它存在于其他缺乏尿素循环的肝外组织中。因此，精氨酸酶II可能具有除尿素循环之外的生理作用，包括多胺、脯氨酸、谷氨酸的合成以及一氧化氮生成的调节。在肝外组织中，精氨酸酶II在肾脏中的高表达可能与肾脏功能相关。本研究旨在确定不同年龄小鼠肾脏中精氨酸酶II活性和表达的年龄相关变化。还研究了饮食限制对调节精氨酸酶II年龄依赖性变化的影响。结果表明，随着年龄的增长，肾脏精氨酸酶II活性显著下降（与2个月大的小鼠相比，6个月和18个月大的小鼠分别为p<0.01和p<0.001），这是由于其蛋白质和mRNA水平降低所致（与2个月大的小鼠相比，6个月和18个月大的小鼠均为p<0.001）。对2个月和18个月大的小鼠进行为期三个月的长期饮食限制，均显著上调了精氨酸酶II的活性和表达水平（与自由采食组相比，分别为p<0.01和p<0.001）。这些发现清楚地表明，衰老过程中精氨酸酶II水平的降低可能会影响肾功能的下降。肾脏中精氨酸酶II这种年龄依赖性的下调可通过饮食限制得到缓解，这可能有助于维持此类功能。
