👤 Julia G Kiefer

Lipoprotein kinetics are a crucial factor in understanding lipoprotein metabolism because a prolonged time in circulation can contribute to the atherogenic character of B-lps (ApoB-containing lipoproteins). We developed a genetically encoded B-Lp reporter, LipoTimer, in which the zebrafish endogenous By quantifying the red population of ApoB-Dendra2 over time, we found that B-lp turnover in wild-type larvae becomes faster as development proceeds. Mutants with impaired B-lp uptake or lipolysis present with increased B-lp levels and half-life. In contrast, mutants with impaired B-lp triglyceride loading display slightly fewer and smaller B-lps, which have a significantly shorter B-lp half-life. Furthermore, we showed that chronic high-cholesterol feeding is associated with a longer B-lp half-life in wild-type juveniles but does not lead to changes in B-lp half-life in lipolysis-deficient In conclusion, the new LipoTimer reporter allows for direct in vivo examination of B-lp kinetics, which can be used to better understand the role of lipoprotein modifier genes and environmental factors (eg, diet) on B-lp lifetime. Show less

Carbohydrate response element-binding protein (ChREBP) is a transcription factor activated by glucose metabolites that orchestrates the expression of genes involved in glycolysis, de novo lipogenesis, and ATP homeostasis. Inadequate ChREBP activity impairs the cellular adaptations to glucose exposure and in humans associates with dyslipidemia, fatty liver disease, and type 2 diabetes. ChREBP activity is regulated by cytosolic-nuclear translocation involving its low-glucose inhibitory domain (LID). Whether this domain is targeted by post-translational lysine acetylation is unknown. Here we report a novel LID acetylation site that controls activity and protein interactions of ChREBP. Mutation of this residue increased glucose-induced activity and target gene expression of ChREBP. Mechanistically, mutant ChREBP protein showed more nuclear localization and enhanced genomic binding to a target promoter. Interactions with proteins that exhibit differential binding upon glucose exposure were attenuated by the mutation, demonstrating the importance of the LID in the formation of the protein interactome. Particularly interactions with 14-3-3 proteins, factors that regulate cytosolic/nuclear trafficking of ChREBP, were reduced, whereas interactions with proteins of the nucleosome remodeling deacetylase complex (NuRD) were increased. These molecular insights may shape new therapeutic strategies to target ChREBP activity and counteract metabolic diseases. Show less