Deletion of a single allele of Cx43 is associated with a reduction in the gap junctional intercellular communication and increased cell proliferation of mouse lung pneumocytes type II.
OBJECTIVE
Connexins (Cx) are proteins that form the gap junctional channels at neighbouring plasma membranes between adjacent cells. Cxs are involved in cell communication, which is reportedly correlated with cell proliferation and differentiation. Alterations in connexin expression and/or gap junctional intercellular communication (GJIC) capacity have long been postulated to be important in a number of pathological conditions including cancer. This study was performed to determine the consequences of the deletion of a single allele of Gja1 (Cx43 gene) in Alveolar Type II cells (APTIIs), and its impact on GJIC and cell proliferation.


METHODS
In order to do so, APTIIs from wild type (Cx43(+/+)) and heterozygous (Cx43(+/-)) mice were harvested and cultured for 4 days. The GJIC capacity was evaluated by scrape-loading method, with the transfer of lucifer yellow dye. The expression of Cx43 was evaluated by immunofluorescence method and Western blotting. Cell proliferation was evaluated by 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide assay.


RESULTS
It was observed that GJIC capacity was significantly reduced and cell proliferation index was significantly higher in Cx43(+/-) cells compared to Cx43(+/+) cells.


CONCLUSIONS
These results show that knocking out one allele of Cx43 leads to a lower cell to cell communication capacity, and consequently induces a higher cell proliferation. Because chemically induced lung adenomas in mice are known to originate from APTIIs, these alterations may play a critical role in their susceptibility to lung carcinogenesis.
Avanzo
J L
JL
Laboratory of Experimental Oncology, Department of Pathology, Faculty of Veterinary Medicine and Animal Science, University of São Paulo, Brazil.
Mennecier
G
G
Mesnil
M
M
Hernandez-Blazquez
F J
FJ
Fukumasu
H
H
da Silva
T C
TC
Rao
K V K
KV
Dagli
M L Z
ML
D000483:Alleles; D000818:Animals; D002450:Cell Communication / Q000502:physiology*; D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured; D018031:Connexin 43 / Q000235:genetics*; D017629:Gap Junctions / Q000502:physiology*; D017353:Gene Deletion; D020022:Genetic Predisposition to Disease; D008168:Lung / Q000166:cytology*; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology; D051379:Mice; D008815:Mice, Inbred Strains; D008817:Mice, Mutant Strains; D020133:Reverse Transcriptase Polymerase Chain Reaction
D018031:Connexin 43