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SS Zhang, C Zhang, J Wei, CJ Barnstable, X-Y Fu; Activation of STAT in Response to Growth Factors or Cytokines in Retina Explant Culture . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3652.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Growth factors and cytokines play an important role in the development of central nervous systems including neuron of the retina. These extrinsic factors are major elements in the neuronal proliferation and differentiation. However, the molecular pathway that triggers cell fate determination or cell growth remains unclear. Those external molecules can activate intracellular signal transduction or transcription factors via their membrane receptors or intracellular protein tyrosine kinases. Signal transducer and activator of transcription (STAT) proteins contribute a signaling pathway used by various cytokines and growth factors to regulate gene expression and cellular alterations. Methods: In present studies, we used a retinal explant culture system to investigate STATs in response to extrinsic factors during mouse retinal development. Retina from embryonic and neonatal stages were used to study whether Stat3 and Stat1 activation in response to FGF1 (50ng/ml), FGF2 (50ng/ml), CNTF (25ng/ml), LIF (25ng/ml), EGF (25ng/ml), IFN-alpha (10ng/ml), and IFN-gamma (10ng/ml). A final concentration of 10 mM of BrdU was used for tissue culture system. After for 12h incorporation into the DNA of replicating cells, proliferating cells were detected using a monoclonal anti-BrdU antibody. Explanted retinas were fixed with 4% paraformaldehyde in PBS for 24h at 4*C. After three washes with PBS, fixed explants were dehydrated through washes in a series of graded ethanol and embedded in paraffin. All samples for one experiment were placed in the same blocks and sectioned for immunohistochemistry. Results: Retina from embryonic and neonatal stages showed that Stat3 but not Stat1 activation in response to FGF1, FGF2, CNTF, LIF, EGF, IFN-alpha, and IFN-gamma. 24h after stimulation, Stat3 activation was detected in the outermost neuroblastic layer in response to CNTF, LIF, FGF1, and IFN-alpha but not FGF2, IFN-gamma, and EGF, indicating that Stat3 may be involve in neural stem cell proliferation in an immediate response to growth factors or cytokines. Furthermore we have evidence showing that an increase of the number of cells incorporating BrdU was related to cytokine stimuli and co-localized with phosphorylated Stat3 expression even in the later stages. Conclusion: This result suggested that Stat3 play an essential role in response to extrinsic factors and then promotes neural precursor proliferation.
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