On-line analysis of gap junctions reveals more efficient electrical than dye coupling between islet cells.
Pancreatic beta-cells constitute a well-communicating multicellular network that permits a coordinated and synchronized signal transmission within the islet of Langerhans that is necessary for proper insulin release. Gap junctions are the molecular keys that mediate functional cellular connections, which are responsible for electrical and metabolic coupling in the majority of cell types. Although the role of gap junctions in beta-cell electrical coupling is well documented, metabolic communication is still a matter of discussion. Here, we have addressed this issue by use of a fluorescence recovery after photobleaching (FRAP) approach. This technique has been validated as a reliable and noninvasive approach to monitor functional gap junctions in real time. We show that control pancreatic islet cells did not exchange a gap junction-permeant molecule in either clustered cells or intact islets of Langerhans under conditions that allowed cell-to-cell exchange of current-carrying ions. Conversely, we have detected that the same probe was extensively transferred between islet cells of transgenic mice expressing connexin 32 (Cx32) that have enhanced junctional coupling properties. The results indicate that the electrical coupling of native islet cells is more extensive than dye communication. Dye-coupling domains in islet cells appear more restricted than previously inferred with other methods.
Quesada
Ivan
I
Institute of Bioengineering, Miguel Hernandez University, San Juan Campus, 03550 San Juan de Alicante, Spain.
Fuentes
Esther
E
Andreu
Etelvina
E
Meda
Paolo
P
Nadal
Angel
A
Soria
Bernat
B
D000818:Animals; D001253:Astrocytes / Q000502:physiology; D002450:Cell Communication / Q000502:physiology; D002478:Cells, Cultured; D017630:Connexins / Q000378:metabolism; D001330:Electronic Data Processing; D004594:Electrophysiology; D005452:Fluoresceins; D005453:Fluorescence; D017629:Gap Junctions / Q000502:physiology*; D007515:Islets of Langerhans / Q000166:cytology / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D038761:Photobleaching; D000097002:Gap Junction beta-1 Protein
D017630:Connexins; D005452:Fluoresceins; D000097002:Gap Junction beta-1 Protein; C093616:6-carboxyfluorescein diacetate; C084577:5-carboxyfluorescein diacetate