Autor(es):
Fernandes, Rosa 
; Girão, Henrique ; Pereira, Paulo
Data: 2004
Identificador Persistente: http://hdl.handle.net/10316/12632
Origem: Estudo Geral - Universidade de Coimbra
Detalhes do Documento
High glucose down-regulates intercellular communication in retinal endothelial ...
Descrição
Intercellular communication through gap junctions (GJIC) is most likely relevant to maintaining the integrity of the blood-retinal barrier. In this study, we investigated the mechanism whereby high glucose enhances degradation of connexin 43 (Cx43), thus contributing to a decrease in GJIC. The levels of Cx43 in bovine retinal endothelial cells exposed to high glucose (25 mm) decreased about 50% as compared with controls (5.5 mm glucose). Consistently, the half-life of the protein decreased from 2.3 to 1.9 h. The proteasome inhibitors MG132 and lactacystin prevented the loss of Cx43 induced by high glucose and extended Cx43 half-life. The amount of phosphorylated Cx43 increased in high glucose and after proteasome inhibition. Scrape-loading dye transfer experiments show that high glucose is associated to a decrease of 40% in GJIC. Significantly, this reduction can be reversed by proteasome inhibitors. The decrease in GJIC in cells exposed to high glucose is associated with a loss of Cx43 from the plasma membrane, as demonstrated by immunofluorescence and biotinylation of cell-surface proteins. Results indicate that increased phosphorylation of Cx43 under high glucose is the mechanism targeting Cx43 for degradation by a proteasome-dependent mechanism. Increased degradation of Cx43 and reduction of GJIC in high glucose may be of physiological importance by contributing to endothelial cell dysfunction associated with the breakdown of the blood-retinal barrier in diabetic retinopathy
Intercellular communication through gap junctions (GJIC) is most likely relevant to maintaining the integrity of the blood-retinal barrier. In this study, we investigated the mechanism whereby high glucose enhances degradation of connexin 43 (Cx43), thus contributing to a decrease in GJIC. The levels of Cx43 in bovine retinal endothelial cells exposed to high glucose (25 mm) decreased about 50% as compared with controls (5.5 mm glucose). Consistently, the half-life of the protein decreased from 2.3 to 1.9 h. The proteasome inhibitors MG132 and lactacystin prevented the loss of Cx43 induced by high glucose and extended Cx43 half-life. The amount of phosphorylated Cx43 increased in high glucose and after proteasome inhibition. Scrape-loading dye transfer experiments show that high glucose is associated to a decrease of 40% in GJIC. Significantly, this reduction can be reversed by proteasome inhibitors. The decrease in GJIC in cells exposed to high glucose is associated with a loss of Cx43 from the plasma membrane, as demonstrated by immunofluorescence and biotinylation of cell-surface proteins. Results indicate that increased phosphorylation of Cx43 under high glucose is the mechanism targeting Cx43 for degradation by a proteasome-dependent mechanism. Increased degradation of Cx43 and reduction of GJIC in high glucose may be of physiological importance by contributing to endothelial cell dysfunction associated with the breakdown of the blood-retinal barrier in diabetic retinopathy
Tipo de Documento
Artigo
Idioma Inglês
Idioma Inglês
| Financiadores do RCAAP | |||||||
|
|
|
|
|
|
||