Dietary control of peripheral adipose storage capacity through membrane lipid remodelling.

Genetic and dietary cues are known drivers of obesity, yet how they converge at the molecular level is incompletely understood. Here we show that PPARγ supports hypertrophic expansion of adipose tissue via transcriptional control of LPCAT3, an endoplasmic reticulum (ER)-resident O-acyltransferase that selectively enriches diet-derived omega-6 polyunsaturated fatty acids (n-6 PUFAs) in the membrane lipidome. In mice fed a high-fat diet, lowering membrane n-6 PUFA levels through genetic or dietary interventions results in aberrant adipose triglyceride (TG) turnover, ectopic fat deposition and insulin resistance. Additionally, we detail a non-canonical adaptive response in 'lipodystrophic' Lpcat3 adipose tissues that engages a futile lipid cycle to increase metabolic rate and offset lipid overflow to ectopic sites. Live-cell imaging, lipidomics and molecular dynamics simulations reveal that adipocyte LPCAT3 activity enriches n-6 arachidonate in the phosphatidylethanolamine (PE)-dense ER-lipid droplet interface. Functionally, this localized PE remodelling optimizes TG storage by driving the formation of large droplets that exhibit greater resistance to adipose TG lipase activity. These findings highlight the PPARγ-LPCAT3 axis as a mechanistic link between dietary n-6 PUFA intake, adipose expandability and systemic energy balance.