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Ju Zhang, Judy M. Ogilvie; Expression of Cyclic Nucleotide Gated Channel During Development of Wild Type and rd1 Mouse Retina. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5421.
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© ARVO (1962-2015); The Authors (2016-present)
The rd1 mouse retina is a model of retinitis pigmentosa in which rod photoreceptors begin to undergo apoptosis around postnatal day 10 (P10) and degenerate completely by P21 as a result of a mutation in the Pde6b gene. Pde6 plays a central role in phototransduction in the adult photoreceptor outer segment. Upon light-stimulated activation of Pde, cGMP levels decrease resulting in closure of the cyclic nucleotide gated channels (CNGC) and signal transduction. Here we determine the expression pattern of the two channel subunit genes, CNGA1 and CNGB1, during early postnatal development in the wild type (wt) and rd1 mouse.
The expression level of the two components of cyclic nucleotide gated channel, CNGA1 and CNGB1, were analyzed by quantitative PCR. Isolated retinas were harvested from wt and rd1 mice at P2, P4, P6, P10 and P21. Retinas of both eyes were homogenized together and processed for RNA extraction and c-DNA synthesis. The obtained c-DNA was used as template for quantitative PCR analysis. The ratio was calculated after both the CNGA1 and CNGB1 levels had been normalized to two reference genes, HPRT or beta-actin.
At P2 and P4, no difference was observed in expression of either CNGA1 or CNGB1 in wt compared to rd1 retinas. However, both genes were significantly downregulated in the rd1 retina by P6 and nearly gone by P21 compared to the wt retina. A greater difference in expression for both genes was seen at P6 than at P10.
In the rd1 retina, a mutation in the Pde6b gene leads to an increase in cGMP levels by P6. Several phototransduction genes are expressed in wt retina around this age. The Pde6b gene, however, is expressed embryonically suggesting it may play a different developmental role. Here we show that the earliest significant difference in both CNGC genes is detected at P6. This data suggests that any role for Pde6b during development may be independent of the channels. Delayed differentiation of rod photoreceptors has been described in morphological studies of the rd1 retina. The observation that a greater difference in expression of CNGA1 and CNGB1 was seen at P6 than at P10 is consistent with this delay.
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