Lipid sensing nuclear receptors involved in the pathogenesis of fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) begins with lipid accumulation and progresses toward inflammation and fibrosis. Nuclear receptors (NRs), like the Peroxisome Proliferator-Activated Receptors alpha and gamma (PPARα and PPARy), the Farnesoid X Receptor (FXR), and the Liver X receptor (LXR), regulate genes by heterodimerizing with Retinoid X receptor (RXR). These receptors are emerging targets for pharmaceutical intervention for metabolic diseases.

Systemic and local lipid adaptations underlie regeneration in Drosophila melanogaster and Ambystoma mexicanum.

In regenerating tissues, synthesis and remodeling of membranes rely on lipid turnover and transport. Our study addresses lipid adaptations in intestinal regeneration of Drosophila melanogaster and limb regeneration of Ambystoma mexicanum. We found changes in lipid profiles at different locations: transport, storage organs and regenerating tissues. We demonstrate that attenuating insulin signaling, exclusively in fat storage, inhibits the regeneration-specific response in both the fat storage and the regenerating tissue in Drosophila. Furthermore, in uninjured axolotls we found sex-specific lipid profiles in both storage and circulation, while in regenerating animals these differences subside. The regenerating limb presents a unique sterol profile, albeit with no sex differences. We postulate that regeneration triggers a systemic response, where organs storing lipids play a significant role in the regulation of systemic lipid traffic. Second, that this response may be an active and well-regulated mechanism, as observed when homeostatic sex-differences disappear in regenerating salamanders.