A BMP4-p38 MAPK signaling axis controls ISL1 protein stability and activity during cardiogenesis

Summary During development, cells respond rapidly to intra- and intercellular signals, which induce signaling cascades regulating the activity of transcription factors at the transcriptional and/or post-translational level. The transcription factor ISL1 plays a key role in second heart field development and cardiac differentiation, and its mRNA levels are tightly regulated during cardiogenesis. Here, we show that a BMP-p38 MAPK signaling axis controls ISL1 protein function at the post-translational level. BMP-mediated activation of p38 MAPK leads to ISL1 phosphorylation at S269 by p38, which prevents ISL1 degradation and ensures its transcriptional activity during cardiogenesis. Interfering with p38 MAPK signaling leads to the degradation of ISL1 by the proteasome, resulting in defects in cardiomyocyte differentiation and impaired zebrafish and mouse heart morphogenesis and function. Given the critical role of the tight control of ISL1 activity during cardiac lineage diversification, modulation of BMP4-p38 MAPK signaling could direct differentiation into specific cardiac cell subpopulations.
Highlights • ISL1 is phosphorylated by p38 MAPK at serine 269 • A BMP4-p38 MAPK signaling axis controls ISL1 protein stability • Phosphorylation of ISL1 by p38 regulates its activity during cardiogenesis • p38 Inhibition in vivo results in ISL1 degradation and second heart field defects
In this article, Jing and colleagues describe a key role of BMP4-p38 MAPK signaling in controlling ISL1 protein stability and activity during cardiogenesis through p38-mediated ISL1 phosphorylation at S269. Interfering with p38 MAPK signaling leads to the degradation of ISL1 by the proteasome, resulting in defects in ISL1+ cardiac progenitor cell differentiation and impaired heart morphogenesis and function.