Disease relevance of RXRG

• By d10, when photoreceptors and ganglion cells have been generated and begun to establish their definitive layers, RXRgamma-positive cells were virtually restricted to the photoreceptor layer, and maintained this distribution to posthatch stages [1].

High impact information on RXRG

• We have previously shown that, in the developing chick neural retina, expression of the retinoid X receptor-gamma (RXR-gamma2) nuclear receptor gene is restricted to photoreceptors [2].
• To characterize the mechanisms that regulate expression of this gene in the neural retina, we isolated a chicken RXR-gamma genomic clone containing the RXR-gamma2 promoter and mapped the transcription initiation site by means of ribonuclease protection [2].
• We analysed promoter activity by transient transfection of luciferase reporter gene constructs into cultured cells isolated from embryonic-chick neural retina or facial mesenchyme, which does not normally express detectable RXR-gamma2 transcripts [2].
• These results indicate that regulation of RXR-gamma2 transcription in the developing chick neural retina involves the binding of one or more neural retina-specific protein factors to an enhancer element located approx. 1 kbp upstream of the transcription initiation site [2].
• At stage 10, when migrating neural crest expresses RXR gamma transcripts, we detect no transcripts in the neural tube [3].

Biological context of RXRG

• We detected RXRgamma transcripts as early as 4 days of embryonic development (d4) in central regions of the retina, spreading to more peripheral regions by d8 [1].

Anatomical context of RXRG

• By stage 15, RXR gamma transcripts also appear in an intermittent longitudinal cell column within the mantle zone of the alar plate of the hindbrain, eventually extending into the cerebellar plate rostrally and into the cervical spinal cord caudally, with a gap at about rhombomere 3 [3].
• By stage 13, RXR gamma transcripts accumulate to detectable levels along the midline of the posterior optic tectum, where the neural crest-derived sensory neurons of the mesencephalic trigeminal nucleus are located [3].
• With in situ hybridization assays, we mapped the distribution of retinoid X receptor gamma (RXR gamma) gene transcripts in the central nervous system of the chicken embryo [3].
• Previous studies have demonstrated the presence of RXR gamma transcripts in migrating neural crest and in neural crest derivatives throughout the peripheral nervous system, implicating RXR gamma as an early pan-neural crest marker (Rowe et al. 1991. Development 111:771-778), and in the retina (Hoover et al. 1998. J Comp Neurol 391:204-213) [3].

Analytical, diagnostic and therapeutic context of RXRG

• We have examined the distribution of the retinoid X receptor gamma (RXRgamma) in the developing chicken retina by using in situ hybridization and RNase protection assays [1].

References