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[Changes of phosphorylation states of Cx43 protein in Chinese hamster lung cells induced by SiO2]
Weiwei Wu1, Guogen Mao, Chen Yu
1Women's Hospital, Zhejiang University, School of Medicine, Hangzhou 310006, China.
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.
Conclusion:
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.
Insights
Silica exposure down-regulates gap-junctional communication (GJIC) and internalizes connexin 43 (Cx43) in lung cells. This is linked to Cx43 phosphorylation changes, potentially via protein kinase C (PKC) activation.
Area of Science:
- Cell Biology
- Toxicology
- Biochemistry
Context:
- Silica particles are a known occupational hazard, causing lung diseases.
- Pulmonary alveolar macrophages (PAM) play a role in silica-induced lung injury.
- Cellular communication via gap junctions is crucial for tissue homeostasis.
Purpose:
- To investigate the relationship between silica-induced changes in connexin 43 (Cx43) phosphorylation and its effects on gap-junctional communication (GJIC).
- To explore the mechanism underlying Cx43 internalization and GJIC inhibition in lung fibroblasts exposed to silica.
Summary:
- Western blot analysis revealed distinct phosphorylated Cx43 species (NP, P1, P2, P3) in Chinese hamster lung (CHL) cells exposed to silica-stimulated PAM supernatants.
- Increased silica dosage correlated with elevated levels of P2 and P3 Cx43 bands.
- Inhibition of protein kinase C (PKC) with Palmitoyl-DL-Camitine chloride (PMC) reduced P2 and P3 levels, suggesting a role for PKC in silica-induced Cx43 phosphorylation.
Impact:
- The findings suggest that silica-induced inhibition of GJIC and Cx43 internalization in CHL cells are associated with altered Cx43 phosphorylation states.
- The mechanism may involve the protein kinase C (PKC) activation pathway, similar to phorbol 12-myristate 13-acetate (TPA).
- This research provides insights into the molecular mechanisms of silica toxicity in lung cells.
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