Why does exercise training make us healthier? It's well-known that exercise enhances insulin sensitivity, improves metabolism, and ultimately boosts athletic performance. However, the biological mechanisms behind this adaptation remain incompletely understood.
A new study published in PNAS suggests part of the explanation lies in how skeletal muscle and adipose tissue communicate. The research was led by Jonas Treebak, Associate Professor at the CBMR Center for Basic Metabolic Research at the University of Copenhagen, and Marcelo A. Mori, Assistant Professor at the University of Campinas.
Experiments in mice and humans revealed that short-term exercise training increases levels of the DICER enzyme in fat cells. DICER in fat helps muscles adapt to exercise and improve function by triggering fat cells to release fatty acids into the bloodstream, where muscles need them.
Scientists believe DICER works by regulating microRNA molecules that block fat cells from using glucose in the blood.Their research revealed that mice unable to produce DICER failed to gain exercise adaptations and even became obese.
However, transfusing blood from exercised mice into unexercised mice elevated DICER levels in the latter's fat tissue. This indicates exercise training triggers muscles to release a molecule that causes fat cells to produce more DICER.
Associate Professor Jonas Treebak stated:The concept that skeletal muscle responds to exercise by signaling other tissues isn't new. While the specific signals originating from muscle remain elusive, we've identified a signaling axis between muscle and fat that is crucial for adaptive responses to exercise." He added, "Clearly, the next step is to identify the circulating factor from skeletal muscle and determine the targets of specific microRNAs."