The histone demethylase KDM1A is a multi-faceted regulator of vital developmental processes, including mesodermal and cardiac tube formation during gastrulation. However, it is unknown whether the fine-tuning of KDM1A splicing isoforms, already shown to regulate neuronal maturation, is crucial for the specification and maintenance of cell identity during cardiogenesis. Here, we discovered a temporal modulation of ubKDM1A and KDM1A+2a during human and mice fetal cardiac development and evaluated their impact on the regulation of cardiac differentiation. We revealed a severely impaired cardiac differentiation in KDM1A^-/- hESCs, that can be rescued by re-expressing ubKDM1A or catalytically impaired ubKDM1A-K661A, but not by KDM1A+2a or KDM1A+2a-K661A. Conversely, KDM1A+2a^-/- hESCs give rise to functional cardiac cells, displaying increased beating amplitude and frequency and enhanced expression of critical cardiogenic markers. Our findings prove the existence of a divergent scaffolding role of KDM1A splice variants, independent of their enzymatic activity, during hESC differentiation into cardiac cells.

组蛋白去甲基化酶 KDM1A 是重要发育过程的多方面调节剂，包括原肠胚形成过程中的中胚层和心管形成。然而，尚不清楚 KDM1A 剪接异构体的微调是否对心脏发生过程中细胞特性的规范和维持至关重要。在这里，我们发现了人类和小鼠胎儿心脏发育过程中 ubKDM1A 和 KDM1A+2a 的时间调制，并评估了它们对心脏分化调节的影响。我们发现 KDM1A ^-/- hESCs 的心脏分化严重受损，这可以通过重新表达 ubKDM1A 或催化受损的 ubKDM1A-K661A 来挽救，但不能通过 KDM1A+2a 或 KDM1A+2a-K661A 来挽救。相反，KDM1A+2a ^-/-人胚胎干细胞产生功能性心脏细胞，表现出增加的搏动幅度和频率以及增强的关键心源性标志物的表达。我们的研究结果证明，在 hESC 分化为心脏细胞期间，KDM1A 剪接变体存在不同的支架作用，与它们的酶活性无关。