MED13 and hypothyroidism: Recently, Eric Olson's group reported that the heart controls systemic energy metabolism,fat mass, and body weight via microRNA-208a (miR-208a) and Mediator complex subunit 13 (MED13)signaling (Grueter et al, 2012).miR-208a is encoded by an intron of the α-myosin heavy-chain (MHC) gene andis required for upregulation of βMHC and cardiac growth in response topressure overload or hypothyroidism (van Rooij et al, 2007).