Beta cell coupling and connexin expression change during the functional maturation of rat pancreatic islets

Autor(es)

Carvalho‚ C.P.F. ; Barbosa‚ H.C.L. ; Britan‚ A. ; Santos-Silva‚ J.C.R. ; Boschero‚ AC ; Meda‚ P. ; Collares-Buzato‚ CB

• Tipo de documento: Artigo Científico
• Fonte: Diabetologia; v. 53, n. 7, p. 1428-1437, 2010.

Resumo

Cell-cell coupling mediated by gap junctions formed from connexin (CX) contributes to the control of insulin secretion in the endocrine pancreas. We investigated the cellular production and localisation of CX36 and CX43, and gap junction-mediated beta cell coupling in pancreatic islets from rats of different ages, displaying different degrees of maturation of insulin secretion. The presence and distribution of islet connexins were assessed by immunoblotting and immunofluorescence. The expression of connexin genes was evaluated by RT-PCR and quantitative real-time PCR. The ultrastructure of gap junctions and the function of connexin channels were assessed by freeze-fracture electron microscopy and tracer microinjection, respectively. Young and adult beta cells, which respond to glucose, expressed significantly higher levels of Cx36 (also known as Gjd2) than fetal and newborn beta cells, which respond poorly to the sugar. Accordingly, adult beta cells also showed a significantly higher membrane density of gap junctions and greater intercellular exchange of ethidium bromide than newborn beta cells. Cx43 (also known as Gja1) was not expressed by beta cells, but was located in various cell types at the periphery of fetal and newborn islets. These findings show that the pattern of connexins, gap junction membrane density and coupling changes in islets during the functional maturation of beta cells. (AU)

• Processo FAPESP: 02/13218-0 - Estudo do mecanismo de secreção de insulina em células B pancreáticas durante o período perinatal e na prenhez: participação das vias de sinalização de prolactina e da insulina nas várias etapas do processo secretório e alterações induzidas por desnutrição proteica e distúrbios do metabolismo lipídico
• Beneficiário: Antonio Carlos Boschiero
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 02/11909-5 - Comunicação intercelular e expressão diferencial de proteínas associadas às junções comunicantes na maturação in vivo do pâncreas endócrino
• Beneficiário: Carolina Prado de França Carvalho
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 06/50758-3 - Estudo in vivo e in vitro da importância da comunicação celular no mecanismo de secreção de insulina do pâncreas endócrino de ratos e camundongos normais e diabéticos
• Beneficiário: Antonio Carlos Boschiero
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 99/06846-0 - Mecanismos intracelulares de regulação das junções comunicantes (gap junctions) por hormônios somatotróficos em cultura de células de Ilhotas de Langerhans
• Beneficiário: Carla Beatriz Collares Buzato
• Modalidade de apoio: Auxílio à Pesquisa - Regular