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T. Kanamoto, S. Tanimoto, H. Tamura, H. Okumichi, T. Ue, M. Suzuki, H.K. Mishima; Proteomics Analysis of the Retina of EAAC1–Knock Out Mice: Neuroprotective Effect of PDGF Against Glutamate–Induced Excitotoxicity in Retinal Ganglion Cells . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4839.
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© ARVO (1962-2015); The Authors (2016-present)
L–Glutamate is the major excitatory neurotransmitter in the mammalian retina which expresses the excitatory amino acid transporters. Glutamate transporters are involved in maintaining extracellular glutamate at a low level for normal glutamatergic neurotransmission and to prevent neurons from excitotoxicity. To examine the role of one of the neuronal glutamate transporter EAAT3 (EAAC1) in the retina, changes of protein level in the retina of EAAC1–/– knock–out mice were investigated by proteomics techniques.
Proteomics was performed as standard protocols. Protein samples of EAAC1–/– mice retina were collected, and they were analyzed two–dimensional electrophoresis, and protein spots were stained by silver. Volumes of each spots were analyzed by PD–Quest ( Bio–Rad), compared with ICR mouse retina as negative controls. Some protein spots, protein expressions were apparently changed, were selected as target proteins, and identified by mass–spectrometry analysis. Target proteins were also immuno–histochemically analyzed on mouse retina tissue, and their cell biological activities were examined on RGC5 rat retina cells.
Proteomics analysis indicated that some proteins were up or down regulated in the retina of EAAC1–/– mice, compared to that of control (ICR) mice. Fifteen proteins, which expression was different between EAAC1–/– mice and ICR mice, were identified by massspectrometry. Of these fifteen proteins, there were many proteins which function were unkown including three unnamed proteins. In these fifteen proteins, we have explored the role of platelet–derived growth factor receptor alpha (PDGF–R–Alpha) which expression is high in the retina of EAAC1–/– mice and is undetectable in the ICR mice. We observed that PDGF signaling has a neuroprotective effect on glutamate induced death of RGC–5 cells. Partial inhibition of the neuroprotective action of PDGF signaling was detected upon inhibition of PI3 kinase by treatment with wortmanin.
PDGF may be involved in the glutamate–induced retinal ganglion cells death via PI3K pathway and it will lead to the clarification of glutamine–induced retinal gaglion cells death including glaucoma.
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