![]() ![]() On the other hand, inhibition of RA synthesis with disulfiram, or of RAR receptors with the pan-RAR antagonist Ro-41-5253, or the RARβ antagonist LE135E, greatly reduced the survival of the axotomized neurons. Intraocular injection of all-trans retinoic acid (ATRA), the retinoic acid receptor (RAR) type-α agonist AM80, the RARβ agonist CD2314, or the RARγ agonist CD1530, returned axotomized RGC numbers to almost normal levels. Here we investigate whether RA signaling affects long-term RGC survival at 6 weeks after axotomy. The RA signaling pathway is also present in parts of the adult nervous system, and components of it are upregulated after injury in peripheral nerves but not in the CNS. Retinoic acid (RA) is a vitamin A-derived lipophilic molecule that plays major roles during development of the nervous system. Frog RGCs, on the other hand, suffer only an approximately 50% cell loss, and we have previously investigated the mechanisms by which the application of growth factors can increase their survival rate. Prestained molecular size standards were used to identify bands of the correct molecular weight.Īfter lesions to the mammalian optic nerve, the great majority of retinal ganglion cells (RGCs) die before their axons have even had a chance to regenerate. Lanes 1, control cells lanes 2, cells exposed to RA for 90 min lanes 3 to lane 9, treated cells collected every 30 min. (B) Ten micrograms of DNA-binding proteins obtained from control cells and cells exposed to 10 nM RA was electrophoresed on SDS-polyacrylamide gels, transferred to PVDF membranes, and probed with antibodies against RAR ␣, RAR ␥, or RXR. Five independent experiments with very similar results were conducted. Only data relative to RAR  2 and RAR ␥ 1 are reported, since no modulations were observed for the remaining RARs and RXRs. The degree of amplification was quantitated by scanning densitometry and plotted as a ratio of RAR to  -actin or RXR to  -actin. Values for RAR and RXR mRNAs were normalized to that for  -actin mRNA used as internal standard for each RNA sample. At various times after RA addition, total RNA was isolated and 1 g was analyzed by RT-PCR for RAR or RXR expression as described in the text. (A) SK-N-BE2(c) cells were plated at 10 6 cells per 25-cm 2 tissue culture flask, and after an overnight incubation at 37☌, RA was added (time zero) to a final concentration of 10 nM. Time course of RA-regulated expression of RAR  2 and RAR ␥ 1. ![]()
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