Restoration of cell-to-cell communication in thyroid cell lines by transfection with and stable expression of the connexin-32 gene. Impact on cell proliferation and tissue-specific gene expression.
Normal thyroid epithelial cells coexpress connexin-32 and connexin-43, which form distinct gap junctions. In primary culture, connexin-43 is expressed by thyrocytes in monolayers or reorganized into follicles, whereas the expression of connexin-32 is dependent upon the reconstitution of follicles. To study the functional impact of connexin-32 gap junctions in thyroid cells, we transfected connexin-32 cDNA in two thyroid-derived communication-deficient cell lines, FRT and FRTL-5. The selected clones, which stably expressed connexin-32 at high levels and exhibited high gap junction-mediated dye-coupling, presented a reduced proliferation rate as compared with that of the corresponding wild-type FRT and FRTL-5 cells; the mean population doubling time was increased by approximately 35%. The proliferation of connexin-32-transfected FRTL-5 cells remained thyrotropin-dependent; the range of thyrotropin concentrations that stimulated growth was the same in transfected and control cells. The expression of connexin-32 led to an increase of thyroglobulin gene expression in FRTL-5 cells. The expression of two other tissue-specific proteins, thyroid transcription factor-1 and Pax-8, was unchanged. These findings provide evidence that connexin-32 gap junction-mediated cell-to-cell communication participates in the control of growth and differentiation of thyroid cells.
Statuto
M
M
INSERM U369, Faculté de Médecine Lyon-RTH Laënnec, rue G. Paradin, 69372 Lyon Cedex 08, France.
Audebet
C
C
Tonoli
H
H
Selmi-Ruby
S
S
Rousset
B
B
Munari-Silem
Y
Y
D000818:Animals; D002450:Cell Communication; D002455:Cell Division / Q000235:genetics; D002460:Cell Line; D017630:Connexins / Q000235:genetics*; D005786:Gene Expression Regulation; D051381:Rats; D013954:Thyroglobulin / Q000235:genetics; D013961:Thyroid Gland / Q000166:cytology / Q000378:metabolism*; D015854:Up-Regulation; D000097002:Gap Junction beta-1 Protein
D017630:Connexins; D013954:Thyroglobulin; D000097002:Gap Junction beta-1 Protein