Directly Measuring Atherogenic Lipoprotein Kinetics in Zebrafish with the Photoconvertible LipoTimer Reporter

Area of Science:

• Cardiovascular Biology
• Metabolic Research
• Zebrafish Models

Background:

• Lipoprotein kinetics are vital for understanding lipoprotein metabolism.
• Extended circulation of apolipoprotein-B (ApoB)-containing lipoproteins (B-lps) contributes to atherosclerosis.
• Direct measurement of lipoprotein kinetics in vivo is challenging.

Purpose of the Study:

• To develop a novel method for directly measuring lipoprotein kinetics in live developing animals.
• To investigate the impact of genetic mutations and diet on B-lp metabolism using this new method.

Main Methods:

• Development of a zebrafish genetic reporter (LipoTimer) fusing endogenous ApoBb.1 with the photoconvertible fluorophore Dendra2.
• Quantification of the red fluorescent population of ApoB-Dendra2 over time to assess B-lp turnover.
• Analysis of B-lp kinetics in wild-type and mutant zebrafish larvae and juveniles under varying dietary conditions.

Main Results:

• Zebrafish B-lp turnover accelerates with larval development.
• Impaired B-lp uptake or lipolysis leads to increased B-lp levels and half-life.
• Impaired triglyceride loading results in smaller B-lps with shorter half-lives.
• High-cholesterol feeding prolongs B-lp half-life in wild-type, but not in lipolysis-deficient mutants.

Conclusions:

• The LipoTimer system provides a powerful tool for studying lipoprotein kinetics in vivo.
• Lipoprotein lipolysis is suppressed by the influx of intestinal B-lps after high-fat meals.
• These findings advance our understanding of lipoprotein metabolism and its link to atherosclerosis.