Replacement by a lacZ reporter gene assigns mouse connexin36, 45 and 43 to distinct cell types in pancreatic islets.
Transcripts of three connexin isoforms (Cx36, Cx43 and Cx45) have been reported in rodent pancreatic islets, but the precise distribution of the cognate proteins is still unknown. We determined expression of Cx36 in a cell-autonomous manner using mice with a targeted replacement of the Cx36 coding region by a lacZ reporter gene. For cell-autonomous monitoring of Cx43 expression, we used the Cre/loxP system: Mice carrying the Cx43 coding region flanked by loxP sites (floxed) also carried an embedded lacZ gene that is activated after Cre-mediated recombination in cells with transcriptional activity of the Cx43 gene. Deletion of the Cx43 coding region in beta-cells did not result in the activation of the embedded lacZ reporter gene. Instead, Cx43 expression was found in endothelial cells of the islets of Langerhans in mice with endothelium-specific deletion. Ubiquitous deletion of Cx43 led to a similar endothelial lacZ expression, but again, activity of the reporter gene was not detected in beta-cells. Mice with targeted replacement of the Cx45 coding region by lacZ showed a vascular expression similar to Cx43. The data show that native insulin-producing cells express a connexin isoform (Cx36) which differs from those (Cx43 and Cx45) expressed by vascular islet cells.
Theis
Martin
M
Institut für Genetik, Abteilung Molekulargenetik, Universität Bonn, D-53117 Bonn, Germany.
Mas
Christophe
C
Döring
Britta
B
Degen
Joachim
J
Brink
Christopher
C
Caille
Dorothée
D
Charollais
Anne
A
Krüger
Olaf
O
Plum
Achim
A
Nepote
Virginie
V
Herrera
Pedro
P
Meda
Paolo
P
Willecke
Klaus
K
D000818:Animals; D018031:Connexin 43 / Q000032:analysis* / Q000235:genetics; D017630:Connexins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D004730:Endothelium, Vascular / Q000737:chemistry; D018390:Gene Targeting; D017930:Genes, Reporter; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000098:blood supply / Q000737:chemistry* / Q000166:cytology; D051379:Mice; D008822:Mice, Transgenic; D011993:Recombinant Fusion Proteins / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D001616:beta-Galactosidase / Q000032:analysis / Q000235:genetics*; D000097004:Gap Junction delta-2 Protein
D018031:Connexin 43; D017630:Connexins; D007328:Insulin; D011993:Recombinant Fusion Proteins; D001616:beta-Galactosidase; D000097004:Gap Junction delta-2 Protein; C082920:connexin 45