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S.S. Zhang, L. Chen, C.J. Barnstable; The PI3 Kinase/Akt Signaling Pathway Can Regulate Reactive Gliosis in the Retina . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4898.
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© ARVO (1962-2015); The Authors (2016-present)
Muller glia are the major support cells in the vertebrate retina. Following neuronal damage, Muller cells undergo reactive gliosis, which is characterized by increased expression of GFAP. The PI3 kinase/Akt pathway is believed being an important pathway for cell survival and many other biological processes. Here we explore the role of PI3K/Akt signaling pathways in control of reactive gliosis in mouse retina.
All mouse protocols were in accordance with ARVO guidelines and were approved by the Animal Care and Use Committee of Yale University School of Medicine. Primary Muller glial cells were isolated from C57BL/6 (The Jackson Lab) mouse retina at postnatal day 5 to 10. Muller cells were treated with Domic acid (DoA) 20uM within 10%FBS DMEM. Expression of GFAP, and the activation of Akt were evaluated with confocal microscope and western blotting. Migration, and polarization were evaluated with a monolayer wounding assay. TUNEL assay (Upstate) was used for apoptotic cell detection. C57BL/6 mice were also used for in vivo induction of reactive gliosis by injection of 0.5 ul 10mM Domoic Acid per eye. Whole eyeballs were fixed with 4% paraformaldehyde for morphological and immunohistological studies.
Induction of reactive gliosis in retina is associated with increased activation of PI3 kinase/Akt signaling pathways. A marker for activated Muller glia cell, GFAP protein is highly increased but later than elevated phosphorylation of PI3 kinase and Akt after DoA application. Histologically, the increased activation of Akt is predominantly restricted to Muller glial cells. PI3K inhibitor, LY294002 (50 nM) significantly inhibits the reactive gliosis and GFAP expression in vitro and in vivo. In our in vitro studies, inhibition of PI3 kinase/Akt pathways resulted in inhibition of polarization, migration, and proliferation, but not Muller cell death.
The PI3 kinase/Akt signaling pathway may play a particular role in control of reactive gliosis in mouse retina. Understanding the mechanisms of this process will allow modification and elimination of Muller gliosis in many retina disorders.
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