title: Inhibition of calcium signaling in ultraviolet-irradiated fibroblasts: role of tyrosine phosphorylation and protein kinase C.
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 Ca(2+). UVC-treated V79 cells showed a greatly enhanced permeability to Ca(2+) 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.
authors.affiliation: Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Calcutta, 700064, India.
authors.forename: S
authors.initials: S
authors.lastname: Bagchi
authors.forename: G
authors.initials: G
authors.lastname: Bhaumik
authors.forename: S
authors.initials: S
authors.lastname: Raha
mesh_terms: D017607:Aluminum Compounds / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects*; D002460:Cell Line; D006224:Cricetinae; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D005459:Fluorides / Q000494:pharmacology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D013917:Thrombin / Q000494:pharmacology; D014443:Tyrosine / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D017607:Aluminum Compounds; D014443:Tyrosine; D011493:Protein Kinase C; D013917:Thrombin; D005459:Fluorides; D002118:Calcium; C032311:aluminum fluoride