RNAi of nhx-2 impedes reproductive senescence and aging via restoring mitochondrial membrane depolarization in C. elegans

2019-12-28T06:42:59Z (GMT) by shikha shukla
Neurodegenerative diseases do not have a complete cure yet. The strategies that target overall healthy aging might be very effective in treating such debilitating conditions. Reproductive senescence (RS) is one such phenomenon which could be associated with healthy aging vis-à-vis neurodegeneration. Here, we have employed bioinformatics, functional genomics, and molecular biology approaches to understand the mechanistic association between RS and NDs. Employing RNAi induced silencing we performed a systematic screening of subset of 22 such genes that delay reproductive senescence; on the basis of their effect on the various endpoint of neurodegeneration including α-synuclein aggregation, ROS level, locomotion and effect of estradiol upon the functioning of these genes in transgenic strain NL5901 of C. elegans. Our studies led to the identification of a Na+/H+ exchanger as its silencing had a profound effect on endpoints associated with PD. Further, we performed an in silico analysis and found out that the estradiol receptor is having an affinity towards direct inverse repeats of upstream region of nhx-2. We treated worms with 17 beta-estradiol and it gave rise to the altered mRNA levels of nhx-2. We further observed that RNAi of nhx-2, prolonged reproductive span of the worms by 71.3%. Knockdown of nhx-2 is known to alter pH of the gut so we endeavored to decipher whether the observed effects are correlated with selective food absorption. Performing network analysis, immunoblotting and fecundity assay we found out that nhx-2 RNAi is actually working via SIR-2.1 and in absence of SIR-2.1 effects exerted via nhx-2 are withdrawn. When we performed a co knockdown of sir-2.1 and nhx-2, RNAi of nhx-2 did not alter the fecundity of C. elegans which proves that it is showing its effect via altering the levels and functionality of SIR-2.1. We observed that nhx-2 is actually giving rise to selective food absorption and that is mimicking calorie restriction which in turn altering the levels of SIR-2.1.In order to check the mechanistic insight we blindly performed a real-time analysis of genes associated with several pathways and we found that nhx-2 RNAi is affecting genes of the mitochondrial pathway. We also checked the mitochondrial membrane potential of individual cells of worm sine nhx-2 is a proton exchanger and we found that it also improves mitochondrial health by restoring the depolarization of mitochondrial membrane potential. Hence, knockdown of nhx-2, impedes reproductive senescence, extends healthy reproductive span and ameliorates effects associated with neurodegeneration. The data here substantiates the link between reproductive senescence with aging and neuronal health via genes that can alter all over the reproductive health of C. elegans.

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CC BY 4.0