On October 1, researchers at the University of Copenhagen identified the SLC25A34 mitochondrial protein as a direct metabolic link coordinating brown fat activity with dietary intake, circadian rhythms, and environmental temperature. The study reveals how our bodies manage energy expenditures when faced with unexpected demands like a sudden cold morning or a delayed meal.
Overriding the Biological Clock
Brown fat naturally fluctuates its heat production based on a strict daily schedule, dropping during sleep and peaking before waking. However, scientists discovered that this specific transporter acts as an adaptive switch. While the circadian regulatory protein REV-ERBα suppresses the carrier during sleep, exposure to cold can completely bypass this schedule, increasing its levels by up to 90-fold to generate vital heat.
Dietary intake and metabolic states also control this mechanism through another protein called PPARα. Surprisingly, both fasting and insulin spikes elevate the transporter’s presence. Active brown tissue builds new lipid molecules specifically to burn them for heat, a continuous cycle that clears sugar and fat from the bloodstream. This newly understood carrier sustains the cycle by moving a molecule called oxaloacetate back into the mitochondria.
Potential for Metabolic Therapies
The findings hold significant implications for human health. When researchers silenced the transporter in human brown fat cells, energy burning dropped noticeably. Furthermore, analyzing clinical data from 24 studies showed that individuals with higher expressions of this protein in their subcutaneous white fat were generally leaner and exhibited better metabolic profiles. As Associate Professor Zach Gerhart-Hines noted, targeting a mechanism that is naturally tuned by diet, temperature, and time of day could eventually lead to entirely new therapeutic approaches for obesity and diabetes.