PURPOSE: Ciliary neurotrophic factor (CNTF) has been shown to inhibit the developmental expression of rod differentiation markers in rat retinal cultures. The present study was undertaken to investigate whether CNTF transiently inhibits rod differentiation or induces irreversible changes in the developmental fate of rod precursors. METHODS: The effects of CNTF on rod differentiation were monitored in organotypic slice cultures from early postnatal rat retinas by quantification of opsin-immunoreactive cells. The in vitro formation of the photoreceptor layer was analyzed by light and electron microscopy. The developmental expression of the CNTF receptor in photoreceptors was determined by immunoblot analysis. RESULTS: CNTF did not interfere with the generation of rod precursors, their morphologic differentiation, or the formation of the outer nuclear layer. Inhibition of rod differentiation was reversible. In the continuous presence of CNTF the number of opsin-positive cells increased at a normal rate but with a delay of 3 to 4 days. Developing rods became resistant to CNTF, both in vivo and in vitro, and this correlated temporally with the downregulation of CNTF receptor expression. Receptor downregulation was inhibited by CNTF in a dose-dependent manner. At higher CNTF concentrations with sustained receptor expression, the CNTF-induced decrease in opsin expression was accompanied by an increase in the expression of a bipolar cell marker in rod precursors located in the photoreceptor layer. CONCLUSIONS: These data indicate that, although rod precursors exhibit some phenotypic plasticity in the presence of CNTF, the factor does not induce a switch in the developmental fate of rod precursors but plays a role as a transient and reversible negative regulator of rod differentiation.
PURPOSE:Ciliary neurotrophic factor (CNTF) has been shown to inhibit the developmental expression of rod differentiation markers in rat retinal cultures. The present study was undertaken to investigate whether CNTF transiently inhibits rod differentiation or induces irreversible changes in the developmental fate of rod precursors. METHODS: The effects of CNTF on rod differentiation were monitored in organotypic slice cultures from early postnatal rat retinas by quantification of opsin-immunoreactive cells. The in vitro formation of the photoreceptor layer was analyzed by light and electron microscopy. The developmental expression of the CNTF receptor in photoreceptors was determined by immunoblot analysis. RESULTS:CNTF did not interfere with the generation of rod precursors, their morphologic differentiation, or the formation of the outer nuclear layer. Inhibition of rod differentiation was reversible. In the continuous presence of CNTF the number of opsin-positive cells increased at a normal rate but with a delay of 3 to 4 days. Developing rods became resistant to CNTF, both in vivo and in vitro, and this correlated temporally with the downregulation of CNTF receptor expression. Receptor downregulation was inhibited by CNTF in a dose-dependent manner. At higher CNTF concentrations with sustained receptor expression, the CNTF-induced decrease in opsin expression was accompanied by an increase in the expression of a bipolar cell marker in rod precursors located in the photoreceptor layer. CONCLUSIONS: These data indicate that, although rod precursors exhibit some phenotypic plasticity in the presence of CNTF, the factor does not induce a switch in the developmental fate of rod precursors but plays a role as a transient and reversible negative regulator of rod differentiation.
Authors: Yiwen Li; Weng Tao; Lingyu Luo; Deqiang Huang; Konrad Kauper; Paul Stabila; Matthew M Lavail; Alan M Laties; Rong Wen Journal: PLoS One Date: 2010-03-02 Impact factor: 3.240
Authors: Judith Mosinger Ogilvie; Angela M Hakenewerth; Rachel R Gardner; Joshua G Martak; Virginia M Maggio Journal: Mol Vis Date: 2009-12-23 Impact factor: 2.367