Researchers from Leipzig University and Charité – Universitätsmedizin Berlin have discovered a key mechanism regulating appetite and weight control that helps the brain manage the feeling of hunger. In a study conducted within the framework of the Collaborative Research Centre (CRC) 1423 – Structural Dynamics of GPCR Activation and Signaling, the scientists revealed how the protein MRAP2 (melanocortin 2 receptor accessory protein 2) influences the function of the brain receptor MC4R (melanocortin-4 receptor), which plays a central role in controlling appetite and energy balance. The results were published in Nature Communications.

The MC4R receptor is activated by the peptide hormone MSH and participates in regulating the sensation of hunger. Mutations in this receptor are considered one of the most common genetic causes of severe obesity. Previously, researchers deciphered the three-dimensional structure of the active receptor in complex with ligands and the drug setmelanotide, which reduces the feeling of hunger. This provided new insights into the function of MRAP2 and its role in transporting the receptor to the cell surface, where it can more effectively suppress appetite.

Using advanced fluorescence microscopy and single-cell imaging, the team demonstrated that MRAP2 significantly alters the localization and behavior of MC4R inside cells. Fluorescent biosensors and confocal microscopy revealed that MRAP2 is essential for transporting MC4R to the cell surface, ensuring more efficient signaling that suppresses appetite.

The discovery of this new level of receptor regulation points to promising therapeutic strategies that mimic or modulate MRAP2, potentially aiding in the fight against obesity and metabolic disorders. An interdisciplinary and international research team from Germany, Canada, and the United Kingdom combined expertise in live-cell microscopy, molecular pharmacology, and structural biology, demonstrating the power of an integrated approach to studying receptor regulation.