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

Elizaveta Fasler-Kan¹, Natasha Barteneva², Sylvia Ketterer³, Kerstin Wunderlich³, Jörg Huwyler^1,*, Daniel Gygax¹, Josef Flammer⁴, Peter Meyer^5
1University of Applied Sciences Northwestern Switzerland, Muttenz, Switzerland; ²Immune Diseases Institute and Program in Cellular and Molecular Biology, Children Hospital of Boston, Department of Pathology, Harvard Medical School, Boston, MA, USA; ³Department of Research, University Hospital Basel, Basel, Switzerland; ⁴University Eye Clinic Basel, Basel, Switzerland; ⁵Institute of Pathology, University Hospital Basel, Basel, Switzerland; *Now at Department of Pharmaceutical Sciences University of Basel, Basel, Switzerland

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-a 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-a 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-a, 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.

Keywords: retinal pigment epithelium, ARPE-19, age-related macular degeneration, JAK–STAT pathway