Abstract
Purpose: :
To study if high glucose alters gap junction protein Cx43 expression, its distribution pattern, and intercellular communication in cultures of retinal Muller cells, and in cocultures of retinal Muller cells and pericytes.
Methods: :
Retinal Muller cells (rMC-1) alone, and cocultures of rMC-1 and bovine retinal pericytes (BRPs) were grown in normal (N; 5 mM glucose) or high (30 mM) glucose medium for 7 days. Western blot analysis was performed to determine expression of Cx43 protein, and scrape-load dye transfer (SLDT) technique was performed to assess gap junction intercellular communication (GJIC) activity. Additionally, Cx43 immunostaining was performed to determine Cx43 localization and distribution pattern.
Results: :
Cx43 expression was significantly reduced in both rMC-1 cultures and rMC-1 and BRP cocultures grown in high glucose medium compared to those grown in normal medium (64.4±6.9% of control, p<0.01; 72±16.6% of control, p<0.05,respectively). HG significantly reduced the number of Cx43 plaques in rMC-1 cultures, and rMC-1 and BRP cocultures (66.4±6.7% of control, p<0.01; 70.7±11.4% of control, p<0.05, respectively). GJIC was also significantly reduced in rMC-1 cultures and in rMC-1 and BRP cocultures compared to those grown in N medium (55.5±6.2% of control, p<0.01; 61.2±6.0% of control,p<0.01, respectively).
Conclusions: :
Results indicate that Cx43 expression, localization, and GJIC activity are reduced by high glucose in cultures of rMC-1, and in cocultures of rMC-1 and BRPs. High glucose-induced loss of intercellular communication in retinal Muller cells and between Muller cells and pericytes may negatively impact vascular cell viability and vascular homeostasis, and contribute to retinal dysfunction associated with the pathogenesis of diabetic retinopathy.
Keywords: diabetic retinopathy • Muller cells • gap junctions/coupling