Connexin 36 controls synchronization of Ca2+ oscillations and insulin secretion in MIN6 cells.
Cx36 is the predominant connexin isoform expressed by pancreatic beta-cells. However, little is known about the role of this protein in the functioning of insulin-secreting cells. To address this question, we searched for a cell line expressing Cx36 and having glucose-induced insulin secretion comparable to that of primary beta-cells. By evaluating Cx36 expression in MIN6, betaTC3, RIN2A, INS1, and HIT cell lines, which differ in their sensitivity to glucose, we found that wild-type MIN6 cells fit these requirements. Therefore, we stably transfected MIN6 cells with a cDNA coding for a Cx36 antisense sequence to study the role of Cx36 in these cells. Independent clones of MIN6 cells were obtained that had a markedly reduced Cx36 expression. Loss of Cx36 decreased functional gap junctional conductance in these clones. This alteration impaired the synchronization of glucose-induced [Ca(2+)](i) oscillations and insulin secretion in response to glucose, to secretagogues that increase [cAMP](i), and to depolarizing conditions. These data provide the first evidence that Cx36-made channels 1) mediate functional coupling in MIN6 cells, 2) provide for synchronous [Ca(2+)](i) oscillations, and 3) are necessary for proper insulin secretion in response to metabolizable and nonmetabolizable secretagogues.
Calabrese
Alessandra
A
Department of Morphology, University of Geneva, Switzerland. alessandra.calabrese@medecine.unige.ch
Zhang
Min
M
Serre-Beinier
Véronique
V
Caton
David
D
Mas
Christophe
C
Satin
Leslie S
LS
Meda
Paolo
P
D000666:Amphotericin B / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D020013:Calcium Signaling / Q000502:physiology*; D002460:Cell Line; D017630:Connexins / Q000235:genetics*; D017931:DNA Primers; D004553:Electric Conductivity; D004594:Electrophysiology / Q000379:methods; D017629:Gap Junctions / Q000187:drug effects / Q000502:physiology; D005786:Gene Expression Regulation / Q000502:physiology; D005947:Glucose / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000097004:Gap Junction delta-2 Protein
D000666:Amphotericin B; D017630:Connexins; D017931:DNA Primers; D005947:Glucose; D007328:Insulin; D000097004:Gap Junction delta-2 Protein