"Diet-induced obesity modulates close-packing of triacylglycerols in lipid droplets of adipose tissue"
Lipid droplets (LDs) are oil–in–water emulsion organelles which are present in most eukaryotic cells. LDs are rich in triacylglycerol (TAGs) that regulate essential cellular processes such as nutrient supply and energy storage, especially in fat (adipose) tissue. Although TAG abundance in adipocytes has been linked to metabolic disorders, including obesity and metabolic syndromes, how LDs dynamically package TAGs in response to excessive nutrients remains elusive. We found that LD lipidomes display a remarkable increase in TAG acyl chain saturation under calorie-dense diets turning them conducive to close-packing. Using high-resolution X-ray diffraction, solid-state NMR, and imaging, we show that beyond size expansion, LDs from mice under varied obesogenic diets govern fat accumulation by packing TAGs in different crystalline polymorphs. Consistently, LD membrane tension and tissue elastic modulus in high-calorie-fed mice doubled compared to normal diet. Our data suggest that in addition to expanding, adipose tissue undergoes structural remodeling in response to caloric overload. This work could enable the development of new therapies to combat obesity and associated diseases.
