Mitochondrial Protein UCP5 Protects the Aging Heart and Extends Lifespan in Flies

Mitochondrial uncoupling proteins (UCPs) dissipate the proton gradient across the inner mitochondrial membrane, reducing ATP production but also limiting damaging reactive oxygen species (ROS). In mammals, UCPs are linked to metabolism, ROS regulation, and cardiac health, but their roles in simpler model organisms like Drosophila have been less explored. This study zeroes in on UCP5, the only Drosophila UCP homolog detected in the adult heart proteome, to understand its contribution to cardiac aging and metabolic adaptation.

Using cardiac-specific and systemic genetic manipulation in Drosophila, the researchers overexpressed or knocked down UCP5 and tracked heart function, ROS levels, lifespan, and metabolic markers across age. Fly hearts are functionally analogous to the mammalian heart and serve as an established model for studying cardiac aging.

Key results showed that UCP5 RNA levels decline significantly with age in the heart, implicating it in age-related cardiac deterioration. Overexpressing UCP5 specifically in the heart reduced nuclear ROS in cardiomyocytes and extended overall lifespan, suggesting a cardioprotective, pro-longevity role. However, too much UCP5 also increased fibrillation incidence in an age-dependent manner, revealing a nuanced dose-dependent relationship. Conversely, knocking down UCP5 led to increased asystoles, likely driven by tachycardia, underscoring its necessity for normal rhythm.

Metabolically, UCP5 expression rose under high-fat diet conditions, and systemic overexpression lowered triglyceride levels, indicating an adaptive response to lipid overload. These findings suggest UCP5 acts as a metabolic sensor and cardiac protector.

The study is limited by its use of an invertebrate model, and whether mammalian UCP homologs replicate these cardiac and lifespan effects remains to be confirmed in higher organisms.