Activation of the JAK?STAT intracellular pathway in human retinal pigment epithelialcell line ARPE-19

Background: Retinal pigment epithelial cells constitute an important component of theblood–retinal barrier and play a pivotal role in the development of age-related maculardegeneration (AMD). Understanding the underlying molecular mechanisms is a prerequisitefor developing therapeutic strategies for the treatment of this disease. This study investigatedcytokine-induced changes of the JAK–STAT (Janus tyrosine kinase–signal transducers andactivators of transcription) signaling pathway in the human retinal pigment epithelial cell lineARPE-19 and potential implications for AMD.Methods: Electromobility shift assay, immunofluorescence staining, and flow cytometry wereused 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. StrongSTAT1 activation determined by electromobility shift assay and flow cytometry was demonstratedupon exposure to interferon-γ. Interferon-α upregulated STAT1, STAT2, and STAT3 inARPE-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 cytometryanalysis demonstrated the upregulation of major histocompatibility complex molecules onARPE-19 cells as responses to interferon-α and interferon-γ.Conclusion: Our data demonstrate the upregulation of members of the JAK–STAT signalingpathway 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 mayprove useful for screening of AMD therapeutics.