Sesamin extends lifespan through pathways related to dietary restriction in Caenorhabditis elegans

Abstract

Purpose: Sesamin, a polyphenolic compound found in sesame seeds, has been reported to exert a variety of beneficial health effects. We have previously reported that sesamin increases the lifespan of Caenorhabditis elegans. In this study, we investigated the molecular mechanisms underlying the longevity effect of sesamin in C. elegans.

Methods: Starting from three days of age, Caenorhabditis elegans animals were fed a standard diet alone or supplemented with sesamin. A C. elegans genome array was used to perform a comprehensive expression analysis. Genes that showed differential expression were validated using real-time PCR. Mutant or RNAi-treated animals were fed sesamin, and the lifespan was determined to identify the genes involved in the longevity effects of sesamin.

Results: The microarray analysis revealed that endoplasmic reticulum unfolded protein response-related genes, which have been reported to show decreased expression under conditions of SIR-2.1/Sirtuin 1 (SIRT1) overexpression, were downregulated in animals supplemented with sesamin. Sesamin failed to extend the lifespan of sir-2.1 knockdown animals and of sir-2.1 loss-of-function mutants. Sesamin was also ineffective in bec-1 RNAi-treated animals; bec-1 is a key regulator of autophagy, and is necessary for longevity induced by sir-2.1 overexpression. Furthermore, the heterozygotic mutation of daf-15, which encodes the target of rapamycin (TOR)-binding partner Raptor, abolished lifespan extension by sesamin. Moreover, sesamin did not prolong the lifespan of loss-of-function mutants of aak-2, which encodes the AMP-activated protein kinase (AMPK).

Conclusions: Sesamin extends the lifespan of C. elegans through several dietary restriction-related signaling pathways, including processes requiring SIRT1, TOR, and AMPK.

Keywords: Caenorhabditis elegans; Dietary restriction; Lifespan; Sesamin.