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Miryam A. Fragoso, Rei E. Nakamura, Amit Patel, Hyun Yi, Abigail S. Hackam; Analysis of Wnt and STAT Signaling Pathways in Retinal Cells. Invest. Ophthalmol. Vis. Sci. 2011;52(14):866.
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© ARVO (1962-2015); The Authors (2016-present)
The Wnt signaling is an essential pathway that regulates proliferation and differentiation in the retina. We previously demonstrated that the Wnt pathway is upregulated during retinal degeneration in Muller glia and that its activation protects cultured photoreceptors from oxidative stress. The STAT family of transcription factors also regulates neuroprotection. In age related macular degeneration (AMD), oxidative stress contributes to photoreceptor death and leading to loss of central vision. In this study, we investigated the roles and interactions between the Wnt signaling and STAT3 pathways in retinal cell lines under oxidative stress conditions.
Human retinal pigmented epithelium cell line ARPE19 and human Muller glia cell line MIO-M1 were utilized in this study. Activation of STAT3 was detected by immunofluorescence and Western blots using an antibody against the activated STAT3 protein (Tyr705). Wnt signaling was activated by incubating cells for 24 hours with lithium chloride or Wnt3a. Cells were exposed to oxidative stress (200 µM H2O2) for 24 hours in the presence of Wnt3a or control conditioned media. Viability was measured using Cell Titer Blue viability assays.
Wnt signaling induction by Wnt3a increased viability of ARPE19 cells exposed to oxidative stress by 18% (n=5, p≤0.05). Furthermore, Wnt signaling led to STAT3 activation in ARPE19 cells, as shown by immunofluorescence. Wnt also increased total STAT3 protein in MIO-M1 cells (1.6 fold, n=3, p≤0.05). In contrast, STAT3 overexpression did not activate Wnt signaling in either cell type.
These data indicate that STAT3 is downstream of Wnt, but not the converse. These findings suggest that regulation of STAT3 may be a mechanism of Wnt-mediated neuroprotection in the retina.
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