Vascular endothelial cells serve as barriers between blood components and subendothelial tissue and regulate the blood coagulation-fibrinolytic system. Ionizing radiation is a common physical stimulant that induces a bystander effect whereby irradiated cells influence neighboring cells through signalings, including purinergic receptor signaling, activated by adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP), and adenosine as secondary soluble factors. Human vascular endothelial EA.hy926 cells were cultured and irradiated with γ-rays or treated with ATP, ADP, or adenosine under non-toxic conditions. RNA-seq, gene ontology, and hierarchical clustering analyses were performed. The transcriptome analysis of differentially expressed genes in vascular endothelial cells after γ-ray irradiations suggests that the change of gene expression by γ-irradiation is mediated by ATP and ADP. In addition, the expression and activity of the proteins related to blood coagulation and fibrinolysis systems appear to be secondarily regulated by ATP and ADP in vascular endothelial cells after exposure to γ-irradiation. Although it is unclear whether the changes of the gene expression related to blood coagulation and fibrinolysis systems by γ-irradiation affected the increased hemorrhagic tendency through the exposure to γ-irradiation or the negative feedback to the activated blood coagulation system, the present data indicate that toxicity associated with γ-irradiation involves the dysfunction of vascular endothelial cells related to the blood coagulation-fibrinolytic system, which is mediated by the signalings, including purinergic receptor signaling, activated by ATP and ADP.
Keywords: ATP; Ionizing radiation; RNA-sequencing; Vascular endothelial cell; γ-Ray.