Integrative Cardiovascular Physiology and Pathophysiology Protein tyrosine phosphatase receptor- f 1 deletion triggers defective heart morphogenesis in mice and zebra fi sh

Protein tyrosine phosphatase receptor-f1 (PTPRZ1) is a transmembrane tyrosine phosphatase receptor highly expressed in em- bryonic stem cells. In the present work, gene expression analyses of Ptprz1?/? and Ptprz1þ / þ mice endothelial cells and hearts pointed to an unidentified role of PTPRZ1 in heart development through the regulation of heart-specific transcription factor genes. Echocardiography analysis in mice identified that both systolic and diastolic functions are affected in Ptprz1?/? compared with Ptprz1þ / þ hearts, based on a dilated left ventricular (LV) cavity, decreased ejection fraction and fraction shortening, and increased angiogenesis in Ptprz1?/? hearts, with no signs of cardiac hypertrophy. A zebrafish ptprz1?/? knockout was also gener- ated and exhibited misregulated expression of developmental cardiac markers, bradycardia, and defective heart morphogenesis characterized by enlarged ventricles and defected contractility. A selective PTPRZ1 tyrosine phosphatase inhibitor affected zebra- fish heart development and function in a way like what is observed in the ptprz1?/? zebrafish. The same inhibitor had no effect in the function of the adult zebrafish heart, suggesting that PTPRZ1 is not important for the adult heart function, in line with data from the human cell atlas showing very low to negligible PTPRZ1 expression in the adult human heart. However, in line with the animal models, Ptprz1 was expressed in many different cell types in the human fetal heart, such as valvar, fibroblast-like, cardio- myocytes, and endothelial cells. Collectively, these data suggest that PTPRZ1 regulates cardiac morphogenesis in a way that subsequently affects heart function and warrant further studies for the involvement of PTPRZ1 in idiopathic congenital cardiac pathologies. NEW