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V. P. Sarthy, C. Shum; Ciliary Neurotrophic Factor-Induced Changes in Retinal Müller Cells. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3692.
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© ARVO (1962-2015); The Authors (2016-present)
Ciliary neurotrophic factor (CNTF) is a neuroprotective agent known to retard retinal degeneration in several animal models of retinitis pigmentosa. The molecular mechanisms underlying CNTF-mediated neuroprotection are currently not understood. In a recent microarray analysis of GFP+-Müller cells flow-sorted from CNTF-injected eyes, we were surprised to find that CNTF treatment leads to transcriptional activation of several neurotrophin and proinflammatory cytokine genes in Müller cells. One or more of these might be responsible for the neuroprotective effect of CNTF. The study, however, did not distinguish genes that are directly induced by CNTF from those induced by secondary factors acting back on Müller cells. The goal of the present study was to examine the direct effect of CNTF on Müller cells.
We investigated the effect of CNTF on an established Müller cell line, rMC-1. Actively growing rMC-1 cultures were treated with 50 nM CNTF for periods ranging from 15 to 60 min. RNA was isolated and used to determine transcriptional profiles of known growth factors, cytokines and neurotrophic factors using commercially-available, quantitative real-time PCR array kits (SuperArray Bioscience Corporation, Frederick, MD).
We found that rMC-1 cells treated with CNTF expressed only a small number of growth factors and cytokines or their receptors. At 15 min, the genes induced were (-fold): CxCl1, 3.1; IL10, 4.9; CCl2, 2.0; CxCR5, 2.4; IL6Rα, 2.0; IL2Rγ, 2.8 and STAT3, 2.0. At 30 min, the profile changed to: IL6, 3.5; CxCl1, 2.5; IL10, 3.9 and Myc, 2.5. Finally, at 60 min, gene expression changes included: IL6, 3.6; CCl2, 7.1; CCl7, 2.5; Myc, 2.5; BCl6, 2.2 and STAT3, 2.0. In addition, Fos was strongly induced in rMC-1 cells at all times: 5.9-fold at 15 min, 12.4-fold at 30 min and 4.3-fold at 60 min.
Our studies lead to the surprising finding that CNTF treatment leads to transcriptional activation of only a small number of cytokines in Müller cells. This result suggests that in situ, Müller cell response to CNTF is complex, and that it involves both primary and secondary effects, which strongly increase the repertoire of gene expression changes in Müller cells.
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