Role Of C-Abelson In The Loss Of Genome Integrity In Endothelial Cells In Pulmonary Arterial Hypertension

Introduction: Pulmonary endothelial cells (P-ECs) in idiopathic pulmonary arterial hypertension (iPAH) accumulate DNA lesions during the disease progression; however, the mechanisms underlying this phenomenon remain unclear. Since the non-receptor tyrosine kinase c-Abelson (c-Abl) responds to signals from DNA damage and activates apoptosis, we hypothesized that DNA damage accumulation is due to a loss of c-Abl activity in P-ECs derived from PAH patients. Aims and Objectives: To study the role of c-Abl in the loss of genome integrity in iPAH P-ECs. Methods: Primary cultures of human control and iPAH P-ECs were analyzed by comet assay to determine the amount of DNA strand breaks. P-ECs were treated with a c-Abl inhibitor dasatinib (a specific BCR-ABL tyrosine kinase inhibitor), c-Abl siRNA, or DPH (a c-Abl activator) to analyze DNA lesions by comet assays and the activation of DNA repair pathways by Western blotting. Cleaved caspase-3 expression was also measured to determine the level of apoptosis. Results: iPAH P-ECs display a larger amount of DNA strand breaks compared to control P-ECs along with higher apoptosis and impaired c-Abl expression and activity. Treatment of control P-ECs with dasatinib generates more DNA damage and apoptosis than vehicle conditions and alters the DNA repair pathways. Consistent with these observations, downregulation of c-Abl by RNA-interference in control P-ECs resulted in an increase in DNA damage and apoptosis, whereas upregulation of c-Abl with DPH treatment reduced DNA damage and apoptosis levels in iPAH-ECs. Conclusions: Our results demonstrate a central role of c-Abl in the loss of DNA integrity in iPAH P-ECs.