Adhesion GPCR, latrophilin-2, specifies cardiac lineage commitment through CDK5, Src, and P38MAPK

Identifying lineage-specific markers is pivotal for understanding developmental processes and developing cell therapies. Here, we report a new cardiomyogenic cell surface marker latrophilin-2 (Lphn2), an adhesion G protein-coupled receptor. When mouse and human pluripotent stem cells (PSCs) were stimulated with BMP4, Activin A, and bFGF, they differentiated into cardiac lineage cells. Lphn2 was selectively expressed on cardiac progenitor cells (CPCs) and cardiomyocytes (CMCs) during the differentiation of mouse PSCs, and cell sorting with an anti-Lphn2 antibody promoted the isolation of populations highly enriched in CPCs and CMCs. Lphn2 knock-down or knock-out PSCs did not express cardiac genes. 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 cyclin-dependent kinase 5 (CDK5) at Tyr15. We identified CDK5, Src, and P38MAPK as key downstream molecules of Lphn2. These findings provide a valuable tool for isolating cardiomyogenic progenitors and CMCs from PSCs and shed light on the still-unknown mechanisms of cardiac differentiation. 6 samples are analyzed by 3 groups.