[Changes of phosphorylation states of Cx43 protein in Chinese hamster lung cells induced by SiO2].
OBJECTIVE
To investigate whether cellular gap-junctional communication(GJIC) down-regulation and the internalization of connexin 43(Cx43) in Chinese hamster lung fibroblasts (CHL) induced by silica-stimulated pulmonary alveolar macrophages (PAM) supermatant is related with the phosphorylation states of Cx43 protein.


METHODS
Western-blot analysis was used to identify phosphorylated Cx43 species.


RESULTS
Samples from membrane protein, total protein and nucleoprotein in CHL cells with 50-500 micrograms/ml doses of silica-stimulated PAM supernatants showed NP, P1, P2, P3 four immunoreactive bands of Cx43 protein by contrast with the control group and 0 microgram/ml SiO2 group. And with the dose of SiO2 increased, the increment of the levels of P2 and P3 was observed. Moreover, the groups treated with SiO2 and protein kinase C inhibitor, Palmitoyl-DL-Camitine chloride (PMC), simutaneously showed reduced level of P2 and P3, as compared with the groups treated with SiO2 only.


CONCLUSIONS
The inhibition of GJIC and the internalization of Cx43 by SiO2 in CHL cells may relate to the changes of phosphorylation states of Cx43, and its mechanism may be similar to that of phorbol 12-myristate 13-acetate (TPA), i.e. via PKC activation pathway.
Wu
Weiwei
W
Women's Hospital, Zhejiang University, School of Medicine, Hangzhou 310006, China.
Mao
Guogen
G
Yu
Chen
C
D000818:Animals; D002450:Cell Communication / Q000187:drug effects; D002460:Cell Line; D018031:Connexin 43 / Q000378:metabolism*; D006224:Cricetinae; D017629:Gap Junctions / Q000187:drug effects; D008168:Lung / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation; D012822:Silicon Dioxide / Q000633:toxicity*
D018031:Connexin 43; D012822:Silicon Dioxide