The role of latrophilin-2 in maintaining cardiac cell-to-cell junctions and its implications for dilated cardiomyopathy and sudden death

Abstract Background Identifying genes that are important for maintaining heart function and characterizing their roles and pathways are essential for developing therapeutic approaches. Latrophilin-2 (LPHN2), a relatively unknown GPCR, critically contributes to differentiation from pluripotent stem cells (PSC) to the cardiac lineage, but it is not known whether LPHN2 is active in the adult heart. Purpose In this study, we explored the functions of LPHN2 in adult hearts. Methods and Results To determine whether there is an association between variation in LPHN2 and cardiac phenotypes in humans, we used gnomAD and UK Biobank data. The data suggested that LPHN2 variants could be fatal. Accordingly, we developed a mouse model for further analysis of Lphn2. Deletion of Lphn2 causes embryonic lethality, so we generated a cardiac-specific, tamoxifen-inducible Lphn2 conditional knockout mouse (Lphn2icKO mouse) by cross-breeding Lphn2flox/flox mice with the TMX-inducible Cre recombinase (MerCreMer) under control of the α-Myh6 (α-myosin heavy chain) promoter mice. After administering tamoxifen, we found that the left ventricle became dilated and the systolic function was decreased, and gaps were created between cardiomyocytes. We also observed ventricular tachycardia and atrioventricular block associated with the dilated cardiomyopathy and subsequent sudden cardiac death. Cell-to-cell junctions (adherence, gap, and desmosomes,) were found to be dysregulated in the Lphn2icKO adult mouse heart and the heart at embryonic day 13.5 of Lphn2−/− (homozygous Lphn2 deficiency). To investigate Lphn2 function in a disease model, we generated a myocardial infarction (MI) in Lphn2icKO mice. MI with tamoxifen group showed wide QRS tachycardia and various types of block, and a survival reduction of 40% compared with that of the MI group. Regarding underlying mechanisms, we found that PGC-1α, a factor downstream of p38-MAPK that contributes to arrhythmia and maturation of PSC-derived cardiomyocytes, was downregulated (Figure). Conclusions LPHN2 is a key molecule that maintain adult heart integrity via its effects on cell-to-cell junctions, and the deficiency of Lphn2 exacerbates heart failure. Our findings provide evidence in support of LPHN2 being a pivotal regulator of heart function through the p38-MAPK-PGC-1α pathway.Schematic illustration