👤 Louis-Philippe Laurin

The melanocortin-4 receptor is a G protein-coupled receptor and a key regulator of appetite and metabolism. It can interact with the melanocortin-receptor accessory protein 2, a single transmembrane helix protein known to interact with several different G protein-coupled receptors. However, the consequences of this interaction are not completely understood. Here we report that co-expression of melanocortin-receptor accessory protein 2 has multiple effects on the melanocortin-4 receptor: it enhances G protein-mediated signaling and simultaneously impairs β-arrestin2 recruitment and, consequently, internalization. In addition, co-expression of melanocortin-receptor accessory protein 2 leads to an increased number of monomers of melanocortin-4 receptor by disrupting receptor oligomers. A structural homology model of the active state melanocortin-4 receptor - melanocortin-receptor accessory protein 2 - Gα Show less

Patients with advanced chronic kidney disease have lower health-related quality of life (HRQOL) than the general population. There is uncertainty regarding patterns of HRQOL changes before dialysis initiation. This study aimed to characterise HRQOL trajectory and assess its potential association with intended dialysis modality. This prospective single-centre cohort study followed adults with an estimated glomerular filtration rate ≤15 mL/min/1.73 m One hundred and nine patients were included. At baseline, crude physical composite summary (PCS) (45 ± 10 vs. 39 ± 8) was higher in patients choosing home dialysis ( Patients choosing home dialysis had improved MCS over time compared to those not selecting home dialysis. More work is needed to determine how differences in processes of care and/or unmeasured patient characteristics modulate this association. Show less

The melanocortin 4 receptor (MC4R) plays a role in energy homeostasis and represents a target for treating energy balance disorders. For decades, synthetic ligands have been derived from MC4R endogenous agonists and antagonists, such as setmelanotide used to treat rare forms of genetic obesity. Recently, animal venoms have demonstrated their capacity to provide melanocortin ligands with toxins from a scorpion and a spider. Here, we described a cone snail toxin, N-CTX-Ltg1a, with a nanomolar affinity for hMC4R but unrelated to any known toxins or melanocortin ligands. We then derived from the conotoxin the linear peptide HT1-0, a competitive antagonist of Show less

The Melanocortin-4 Receptor (MC4R) plays a pivotal role in energy homeostasis. We used human MC4R mutations associated with an increased or decreased risk of obesity to dissect mechanisms that regulate MC4R function. Most obesity-associated mutations impair trafficking to the plasma membrane (PM), whereas obesity-protecting mutations either accelerate recycling to the PM or decrease internalization, resulting in enhanced signaling. MC4R mutations that do not affect canonical Gα Show less