Activation of the JAK-STAT intracellular pathway in human retinal pigment epithelial cell line ARPE-19

Background: Retinal pigment epithelial cells constitute an important component of the blood-retinal barrier and play a pivotal role in the development of age-related macular degeneration (AMD). Understanding the underlying molecular mechanisms is a prerequisite for developing therapeutic strategies for the treatment of this disease. This study investigated cytokine-induced changes of the JAK-STAT (Janus tyrosine kinase-signal transducers and activators of transcription) signaling pathway in the human retinal pigment epithelial cell line ARPE-19 and potential implications for AMD. Methods: Electromobility shift assay, immunofluorescence staining, and flow cytometry were used to evaluate the JAK-STAT pathway in the ARPE-19 cell line. Results: We examined cytokine-induced expression of STATs in the ARPE-19 cell line. Strong STAT1 activation determined by electromobility shift assay and flow cytometry was demonstrated upon exposure to interferon-γ. Interferon-α upregulated STAT1, STAT2, and STAT3 in ARPE-19 cells, while interleukin-6 (IL-6) and IL-4 activated STAT3 and STAT6, respectively. Confocal microscopy identified the nuclear translocation of the STAT proteins. Flow cytometry analysis demonstrated the upregulation of major histocompatibility complex molecules on ARPE-19 cells as responses to interferon-α and interferon-γ. Conclusion: Our data demonstrate the upregulation of members of the JAK-STAT signaling pathway in the ARPE-19 cells upon stimulation with interferon-α, interferon-γ, IL-4, and IL-6. We present a model for these signaling pathways potentially relevant for AMD, which may prove useful for screening of AMD therapeutics.