GROWTH-CONTROL OF 3T3 FIBROBLAST CELL-LINES ESTABLISHED FROM CONNEXIN43-DEFICIENT MICE

Connexins are considered to be involved in cell growth control, on the basis of studies mainly with tumorigenic cells. To study the role of connexin genes in normal cell growth control, we established fibroblas t cell lines from connexin 43 (Cx43)-deficient mice and characterized their growth. Embryonic fibroblasts from wildtype mice (Cx43(+/+)) and those with heterozygous (Cx43(+/-)) and homozygous (Cx43(-/-)) defici encies of the Cx43 gene were cultured and passaged by a 3T3 protocol ( every 3 d, 3 x 10(5) cells/60-mm dish). All cell lines showed a growth crisis during passages 6-15 and then started to grow well. All cell l ines grew at similar rates under the 3T3 protocol, but Cx43-deficient (Cx43(-/-)) cell lines tended to grow faster when they were plated at 105 cells per dish. Cx43(-/-) cells did not express Cx43 and showed li ttle gap-junctional intercellular communication (GJIC), confirming tha t Cx43 is the major connexin responsible for GJIC of these fibroblasts . While all Cx43(+/+) and Cx43(+/-) cell lines expressed Cx43 protein, some of them showed very little GJIC. Those cell lines with high GJIC showed higher levels of the P2 form of Cx43 protein, and more Cx43 wa s localized in the plasma membrane than in cell lines with lower GJIC levels. We investigated effects of serum concentration on cell growth in these cell lines. Although different cell lines responded different ially to these agents, there was no clear relationship between Cx43 ex pression and cell growth stimulation by them. This suggests that Cx43 expression alone is not a strong regulator of mouse fibroblast growth. (C) 1998 Wiley-Liss, Inc.