Inhibition of Calcium Signaling in Ultraviolet-Irradiated Fibroblasts: Role of Tyrosine Phosphorylation and Protein Kinase C

Author： Bagchi S. Bhaumik G. Raha S.

Publisher： Elsevier

ISSN： 0006-291X

Source： Biochemical and Biophysical Research Communications, Vol.261, Iss.2, 1999-08, pp. : 504-510

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Abstract

Our aim was to study whether ultraviolet radiation produced any alterations in the subsequent signaling response of V79 fibroblasts to mitogenic stimulus. In ultraviolet C (UVC)-irradiated V79 fibroblasts, increase in cytosolic calcium in response to thrombin was nearly abolished in the presence of 3 mM external Ca²⁺. UVC-treated V79 cells showed a greatly enhanced permeability to Ca²⁺ which was reversed by pretreatment with genistein, a tyrosine kinase inhibitor. Genistein also alleviated the inhibition of thrombin response caused by UVC. In UVC-treated cells, significant activation of protein kinase C (PKC) occurred only on exposure to 3 mM external calcium and PKC inhibitors (H-7 or staurosporine) reversed UVC-induced adverse effects on the thrombin response. Therefore, it is likely that protein tyrosine phosphorylation by UVC may play a role in the subsequent inhibition of thrombin response in V79 cells through increased calcium influx and activation of PKC.