Inhibition of Sarco-Endoplasmic Reticulum Ca2+ ATPase Extends the Lifespan in C. elegans Worms

Paloma García-Casas,Jessica Arias-Del-Val,Rosalba I Fonteriz,Pilar Alvarez-Illera,Javier Alvarez,Mayte Montero

doi:10.3389/fphar.2018.00669

Abstract

The sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) refills the endoplasmic reticulum (ER) with Ca2+ up to the millimolar range and is therefore the main controller of the ER [Ca2+] level ([Ca2+]ER), which has a key role in the modulation of cytosolic Ca2+ signaling and ER-mitochondria Ca2+ transfer. Given that both cytosolic and mitochondrial Ca2+ dynamics strongly interplay with energy metabolism and nutrient-sensitive pathways, both of them involved in the aging process, we have studied the effect of SERCA inhibitors on lifespan in C. elegans. We have used thapsigargin and 2,5-Di-tert-butylhydroquinone (2,5-BHQ) as SERCA inhibitors, and the inactive analog 2,6-Di-tert-butylhydroquinone (2,6-BHQ) as a control for 2,5-BHQ. Every drug was administered to the worms either directly in the agar or via an inclusion compound with γ-cyclodextrin. The results show that 2,6-BHQ produced a small but significant increase in survival, perhaps because of its antioxidant properties. However, 2,5-BHQ produced in all the conditions a much higher increase in lifespan, and the potent and specific SERCA inhibitor thapsigargin also extended the lifespan. The effects of 2,5-BHQ and thapsigargin had a bell-shaped concentration dependence, with a maximum effect at a certain dose and smaller or even toxic effects at higher concentrations. Our data show therefore that submaximal inhibition of SERCA pumps has a pro-longevity effect, suggesting that Ca2+ signaling plays an important role in the aging process and that it could be a promising novel target pathway to act on aging.

Highlights

The molecular mechanisms responsible for aging are not yet fully understood
Our data show that sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) inhibitors induced a significant increase in C. elegans lifespan, suggesting that Ca2+ homeostasis plays an important role in the mechanisms responsible for aging and survival
As all the mammalian SERCA isoforms, the C. elegans protein is inhibited by thapsigargin, a very potent and specific irreversible inhibitor of SERCA pumps (Zwaal et al, 2001)

Summary

INTRODUCTION

The molecular mechanisms responsible for aging are not yet fully understood. In recent years, evidence has accumulated suggesting a key role in aging for the so-called nutrient-sensitive signaling pathways: the insulin/IGF-1 pathway, the AMP kinase pathway (AMPK), the mTOR kinase pathway, and the sirtuin pathway (López-Otín et al, 2016; Riera et al, 2016). One of the key points in Ca2+ signaling linked to the activity of mTOR and AMPK is the inositol trisphosphate receptor (IP3R), which releases Ca2+ from the endoplasmic/sarcoplasmic reticulum (ER/SR) and is able to transfer Ca2+ from the ER to the mitochondria through close contacts that connect both organelles In this work we have studied the effect of the inhibition of the sarco-endoplasmic reticulum Ca2+ ATPase (SERCA) on survival in C. elegans The rationale of this treatment is that submaximal SERCA inhibition should decrease [Ca2+]ER, leading to a reduced Ca2+ release from the ER and a smaller Ca2+ transfer from ER to mitochondria. Our data show that SERCA inhibitors induced a significant increase in C. elegans lifespan, suggesting that Ca2+ homeostasis plays an important role in the mechanisms responsible for aging and survival

MATERIALS AND METHODS

RESULTS

DISCUSSION

DATA AVAILABILITY STATEMENT