Abstract 252: Adhesion GPCR, Latrophilin-2 Induces Cardiac Differentiation Through CDK5, Contributing to Repair After Myocardial Infarction

There has been an increasing demand for cardiomyocyte (CMC) for research into cardiovascular disease and the toxicology of drug metabolites. We identified a G protein-coupled receptor, latrophilin-2 (Lphn2), as a functional marker for cardiomyogenic lineage cells during both in vitro differentiation from ESCs/iPSCs and in vivo heart development. Lphn2 was selectively expressed on CPCs and CMCs during the differentiation of mouse and human PSCs, and cell sorting with an anti-Lphn2 antibody promoted the isolation of populations highly enriched in CPCs and CMCs. Lphn2 knock-down iPSCs did not express cardiac genes. Heterozygous Lphn2 -KO mice ( Lphn2 +/-) were alive and fertile. Homozygous Lphn2 -/- mice were embryonically lethal and showed underdevelopment of the ventricular myocardium. Interestingly, the hearts of Lphn2 -/- embryos revealed the disrupted conotruncal septation of ventricles at E13.5. Lphn2 induces the expression of the central transcription factors Gata4, Nkx2.5, and Tbx5 in mouse heart development. The amino acid sequence of Lphn2 is highly conserved across humans and mice (95.8% identical). For the purpose of cardiac regeneration, we transplanted PSC-derived Lphn2+ cells into the infarcted heart. Transplantation of Lphn2+ cells significantly reduced the fibrosis area and length compared with those in the PBS-injected control group and Lphn2- cells. Echocardiography revealed significantly small LV dimensions at the systole and diastole, and the LV systolic function was higher in the Lphn2+ cell group than in the control and Lphn2- cell groups. To investigate the molecular mechanism underlying the induction of cardiac differentiation by Lphn2, we used the Phospho Explorer Antibody Array, which encompasses nearly all known signaling pathways. Lphn2-dependent phosphorylation was strongest for CDK5 at Tyr15. We identified CDK5, Src, and P38MAPK as key downstream molecules of Lphn2. Our findings provide a valuable tool for identifying CPCs and CMCs differentiated from PSCs, as well as revealing novel insights into cardiac development. Furthermore, the results of this study could be of potential use in regenerative cell therapy for the restoration of cardiac muscle. Funding Source: This study was supported by "Strategic Center of Cell and Bio Therapy for Heart, Diabetes & Cancer" (HI17C2085) through the Korea Health Industry Development Institute, funded by the Ministry of Health & Welfare, Republic of Korea.