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

Area of Science:

• Cardiovascular Biology
• Genetics
• Metabolic Research

Background:

• Lipoprotein kinetics are vital for understanding lipoprotein metabolism.
• Extended circulation time of ApoB-containing lipoproteins (B-lps) contributes to their atherogenic properties.

Purpose of the Study:

• To develop a novel reporter system for real-time in vivo assessment of B-lp kinetics.
• To investigate the influence of genetic factors and diet on B-lp metabolism and lifespan.

Main Methods:

• Genetically engineered zebrafish with a fusion protein (ApoB-Dendra2) using the endogenous apoBb.1 gene.
• Utilized photoconvertible fluorophore Dendra2 for tracking B-lp circulation and turnover via UV exposure.
• Quantified red fluorescent signal over time to determine B-lp half-life in various mutant models and dietary conditions.

Main Results:

• B-lp turnover accelerates with development in wild-type zebrafish larvae.
• Mutations affecting B-lp uptake or lipolysis increase B-lp levels and half-life.
• Impaired triglyceride loading reduces B-lp size and shortens their half-life.
• High-cholesterol feeding extends B-lp half-life in wild-type juveniles but not in apoC2 mutants, suggesting suppressed lipolysis.

Conclusions:

• The LipoTimer reporter enables direct in vivo analysis of B-lp kinetics.
• This tool facilitates a deeper understanding of how genes and environmental factors, such as diet, modulate B-lp lifetime and metabolism.