Kd. Martyn et al., IMMORTALIZED CONNEXIN43 KNOCKOUT CELL-LINES DISPLAY A SUBSET OF BIOLOGICAL PROPERTIES ASSOCIATED WITH THE TRANSFORMED PHENOTYPE, Cell growth & differentiation, 8(9), 1997, pp. 1015-1027
Immortalized cells from embryonic connexin43 knockout mice (Cx43(-/-))
and homozygous littermates (Cx43(+/+)) were cloned and characterized
to determine whether the absence of Cx43 function would induce observa
ble phenotypic changes. Cells of the Cx43(+/+) clones expressed Cx43 a
nd engaged in gap junctional communication with 10-12 neighboring cell
s. The Cx43(-/-) cells were devoid of Cx43 and communicated to less th
an 1 cell. Electrophysiological analysis indicated that the Cx43(-/-)
cells communicated through Cx45 channels from 8-80-fold less than did
the Cx43(+/+) subclones, which seemed to communicate through Cx43 and
Cx45 channels. The Cx43(-/-) clones grew at faster rates and to higher
saturation densities, had a more spindly morphology, were more refrac
tile, and adhered less well to the substratum than did the Cx43(+/+) c
lones. Reintroducing the Cx43 gene into the Cx43(-/-) clones resulted
in three subclones that communicated to 3-4 cells. Partial restoration
of gap junctional communication in the three subclones was accompanie
d by reduced growth rates and saturation densities (2-fold compared to
that of parental Cx43(-/-) clones) but no reversions in morphology or
cell-substratum adhesion. The increased growth rates and saturation d
ensities, altered morphology, and decreased cell adhesion displayed by
the Cx43(-/-) clones reflect a subset of the properties of transforme
d cells. These studies advance the hypothesis that loss of Cx43 functi
on during development may cause cells to acquire a preneoplastic condi
tion.