Dietary restriction can promote cellular repair, a paper published by National Yang Ming Chiao Tung University researchers showed, a discovery that could help the pharmaceutical industry further its research on countering the effects of aging, contributing author Hsu Ao-lin (許?麟) said.
The paper, published in the Autophagy journal, explores how the S-adenosylmethionine synthetase-1 (SAMS-1) is a critical mediator in dietary restriction responses.
Hsu said his team used roundworms as a test subject as they possess similar genetic sequences to humans, have a short life span and can reproduce at great rates, making them the top pick for test subjects in aging studies.
Photo courtesy of National Yang Ming Chiao Tung University
“Dietary restriction is known to promote autophagy and exert its longevity effect, and although SAMS-1 is a key mediator, very little is known about S-adenosylmethionine (SAM) and SAM-dependent methyltransferase in autophagy and dietary restriction-induced longevity,” Hsu said.
If the roundworm ate less every day, its life cycle — which is usually only up to two weeks — could be extended to three or even four weeks, the study found.
Eating less causes the production of a nutrient-sensing module, Hsu said, adding that the study shows that dietary restriction triggers SAMS-1 to repress the activity of SET-2, a histone H3K4 methyltransferase, by limiting the availability of SAM.
“The reduced H3K4me3 levels promote the expression and activity of two transcription factors, HLH-30/TFEB and PHA-4/FOXA, which both regulate the transcription of autophagy-related genes,” Hsu said.
The two transcription factors jointly act on their target genes, mediating the body’s response to autophagy, thus affecting the lifespan of the animals, Hsu said.
The study shows that if food were scarce, the body would use its limited nutrient resources to prioritize cell repair and increase chances of survival, rather than putting energy into reproduction, Hsu said.
The study was authored by university student Lim Chiao-yin (林喬寅), and coauthored by Caroline Kumsta and Malene Hansen from the California-based Sanford Burnham Prebys research institute. Hsu and associate professor Ching Tsui-ting (金翠庭), who was Lim’s adviser, were contributing authors of the paper.
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