Reptilian uncoupling protein: functionality and expression in sub-zero temperatures.

Area of Science:

• Molecular Biology
• Biochemistry
• Ecology

Background:

• Uncoupling proteins (UCPs) are vital for thermogenesis and metabolic regulation in endotherms.
• Ectotherms, like reptiles, face unique challenges in regulating metabolism and mitigating oxidative stress, especially during temperature fluctuations.

Purpose of the Study:

• To characterize the reptilian uncoupling protein (repUCP) gene in the European common lizard (Lacerta vivipara).
• To investigate the expression patterns and functional role of repUCP in response to cold acclimation and stress.

Main Methods:

• Partial nucleotide sequencing of the repUCP gene.
• Sequence homology analysis with known UCPs from other species.
• Gene expression analysis using quantitative PCR in various lizard tissues under different temperature conditions.
• Mitochondrial respiration assays using isolated skeletal muscle mitochondria.

Main Results:

• The repUCP gene sequence shows significant homology to mammalian, avian, and fish UCPs.
• RepUCP expression is widespread in cold-acclimated lizards and upregulated in muscle tissue upon exposure to sub-zero temperatures.
• Mitochondria exhibit guanosine diphosphate (GDP)-sensitive, non-phosphorylating respiration, indicating functional repUCP activity.
• Increased mitochondrial hydrogen peroxide (H2O2) production is linked to repUCP activity.

Conclusions:

• The repUCP is a functional protein in lizard tissues, playing a role in regulating mitochondrial proton leakage.
• RepUCP expression and function are likely involved in protecting mitochondria against oxidative stress during cold exposure and rewarming.
• The regulatory mechanisms of UCPs may be conserved between endothermic mammals and ectothermic reptiles.