Metabolism

In 2014, the International Olympic Committee named a syndrome affecting many of its athletes: relative energy deficiency in sport, or REDs. Athletes develop REDs when they consistently expend more energy through their physical activity than they take in through their diet. Over time, this prolonged energy deficit can lead to a wide range of symptoms, including hormonal and reproductive issues, insomnia and fatigue, bone weakness and injury, and a higher risk of anxiety and depression. It’s now estimated that more than 40% of professional athletes have REDs, and the rate could be even higher in recreational athletes and exercisers. Despite its high prevalence, little is known about REDs on a cellular and molecular level—until Professor Satchidananda Panda, postdoctoral researcher Laura van Rosmalen, and colleagues created a landmark mouse model of REDs. By studying these mice, they discovered that REDs affects organ size and gene expression patterns across the entire body. What’s more, the syndrome appears to impact male and female mice differently: In males, kidney health was most significantly impacted, while in females, reproductive health and muscle mass were most affected. This work is helping the researchers identify potential biomarkers to improve REDs diagnosis, and also reveals new molecular targets for future therapeutics to halt, reverse, or prevent the syndrome altogether.

Our bodies rely on little molecules called amino acids—aptly nicknamed the building blocks of life—that come together to form proteins and carry out bodily functions like digesting, growing, repairing, and so much more. Maintaining a constant supply of these important amino acids requires participation from the liver, kidneys, and circulatory system. But for people with an age-related retinal disease like macular telangiectasia, important amino acids like serine and glycine are depleted. New research from Professor Christian Metallo, visiting graduate student Esther Lim, Salk colleagues, and collaborators at Lowy Medical Research Institute and Scripps Research has revealed how a partial genetic deletion in an important metabolic enzyme (PHGDH) leads to lower levels of circulating serine, and how this contributes to dysfunction between the brain’s visual and non-visual systems. Importantly, they show that dietary serine supplementation can reverse serine-associated retinopathy and peripheral neuropathies.