Abstract
Intracellular triacylglycerol (TAG) is a ubiquitous energy storage lipid also involved in lipid homeostasis and signaling. Comparatively, little is known about TAG’s role in other cellular functions. Here we show a pro-longevity function of TAG in the budding yeast Saccharomyces cerevisiae. In yeast strains derived from natural and laboratory environments a correlation between high levels of TAG and longer chronological lifespan was observed. Increased TAG abundance through the deletion of TAG lipases prolonged chronological lifespan of laboratory strains, while diminishing TAG biosynthesis shortened lifespan without apparently affecting vegetative growth. TAG-mediated lifespan extension was independent of several other known stress response factors involved in chronological aging. Because both lifespan regulation and TAG metabolism are conserved, this cellular pro-longevity function of TAG may extend to other organisms.
Highlights
Lipid is essential for all life forms on earth
Triacylglycerol (TAG) is a ubiquitous lipid species well-known for its roles in storing surplus energy, providing insulation, and maintaining cellular lipid homeostasis
Our results are reminiscent of certain animal studies linking higher body fat to longer
Summary
Lipid is essential for all life forms on earth. Polar lipids, most notably phospholipids, are the primary components of biological membranes, whereas neutral lipids such as triacylglycerols (TAG; or triglycerides, TG), are long believed to store excessive energy and to provide thermal and physical insulation for animals. TAG metabolism is linked to the overall lipid homeostasis in cells and the organism [1]. This is commonly achieved via diacylglycerol, DAG, which is a shared precursor for TAG and phospholipids biosynthesis. In many organisms, TAG accumulation is not a response of surplus nutrients, but of different stresses. Even the oleaginous marine alga Nannochloropsis species increase the TAG content by 50% when starved of nitrogen, and to a lesser extent when stressed by high light and salinity [4]. By storing chemical energy and materials for membrane lipid biosynthesis, TAG helps the underlying cells quickly resume robust metabolism and growth when conditions improve. Whether the existence of TAG in cells affords other benefits for survival through the environmental stress remains an unaddressed question
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