Targeted downregulation of estradiol binding Na⁺/H⁺exchangernhx-2,mimics calorie restriction, extends reproductive longevity and ameliorates effects associated with alpha synuclein aggregation inC. elegans

Abstract

Setting in of reproductive senescence (RS) gives rise to several changes, making aged individuals susceptible to neurodegenerative diseases, cardiovascular and bone disorders amongst others. The present study deciphers the association of reproductive senescence, presence/absence of the sex hormone estradiol with age-associated neurodegenerative diseases. We employed RNAi induced silencing of a subset of 22 genes that are known to delay RS, followed by studies on alpha-Synuclein aggregation and associated effects in the transgenic C. elegans. These studies led us to fuctional characterisation of the Na+/H+ exchanger, expressed exclusively in gut. We found that RNAi of nhx-2 ameliorates the affects associated with alpha-Synuclein aggregation via mimicking dietary restriction as it alters food absorption from the gut. Our studies further elucidated that such effects are Sir-2.1 driven as nhx-2 RNAi did not delay reproductive senescence when sir-2.1 was silenced concurrently. As estradiol plays a central role in both reproductive health as well as neuronal health, we performed structural binding analysis that demonstrated the binding potential of the estradiol receptor NHR-14 with nhx-2 gene. Hence, we treated the worms with estradiol and observed that the transcription levels of nhx-2 were elevated above the endogenous level. To unravel the underlying molecular mechanism of induction we performed ChIP analysis and it revealed that estradiol treatment gives rise to enhanced NHX-2 levels through inducing the promoter specific histone H3 acetylation (H3K9) and lysine methylation (H3K4me3).Graphical abstractHIGHLIGHTSSilencing of a sodium proton antiporter nhx-2 of gut ameliorates effects associated with alpha-Synuclein aggregation via mimicking dietary restriction in C. elegans.We have established a genetic cross to construct a strain that expresses mCherry SIR-2.1 ubiquitously and α-Synuclein in muscles, that assists in corroborating the link between NHX-2 and SIR-2.1.Human 17-β-Estradiol treatment induces the expression of nhx-2, through inducing the promoter specific histone H3 acetylation (H3K9) and lysine methylation (H3K4me3).Effects associated with nhx-2, including prolonged reproductive span and neuroprotective effects, are SIR-2.1 driven.nhx-2 silencing decreases alpha-Synuclein aggregation however estradiol mediated overexpression above the endogenus level, does not amend the aggregation any further.