All-Trans Retinoic Acid Regulates Cx43 Expression, Gap Junction Communication and Differentiation in Primary Lens Epithelial Cells

Abstract

Purpose: To examine the effect of all-trans retinoic acid (ATRA) treatment on connexin 43 (Cx43) expression, gap junction intercellular communication (GJIC), and cellular differentiation in primary canine lens epithelial cells (LEC).Methods and Materials: Dose and time-dependent effects of ATRA on Cx43 protein, mRNA and GJIC, were assessed by immunoblotting, quantitative reverse transcription polymerase chain reaction (qRT-PCR), and scrape loading/dye transfer assays, respectively. Expression of β crystallin was evaluated by immunoblotting.Results: Treatment with ATRA at non-cytotoxic concentrations significantly increased Cx43 protein, mRNA and GJIC in primary canine LEC. Treatment with ATRA for five and seven days increased levels of β crystallin, a protein marker of LEC differentiation. Inhibition of GJIC via pre-treatment with a synthetic inhibitor, 18-α glycyrrethinic acid (AGA), reduced ATRA-induced increases in Cx43 and GJIC and partially blocked ATRA-induced β crystallin protein.Conclusions: Treatment with ATRA significantly increased Cx43 expression and GJIC in canine LEC, and these effects were associated with increased LEC differentiation. Results from this study suggest that functional gap junctions may play a role in the modulation of cellular differentiation in primary canine LEC.