CHROMOSOMAL LOCALIZATION OF THE HUMAN RETINOID-X RECEPTORS

The recently described retinoid X receptors (RXRs) respond to the nove l retinoid 9-cis-retinoic acid and also serve as heterodimeric partner s for the vitamin D, thyroid hormone, and retinoic acid receptors (VDR , TR, and RAR, respectively). In this work, we report high-resolution localization of the human RXR genes within cytogenetic bands and also within a standard reference map of cosmid DNA markers on human chromos omes. We have determined the location of the human RXR genes by pairwi se hybridization of the RXR cosmids and reference markers, using fluor escence in situ hybridization. We localized (i) RXR alpha (RXRA) to ch romosome 9 band q34.3; (ii) RXR beta (RXRB) to chromosome 6 band 21.3; and (iii) RXR gamma (RXRG) to chromosome 1 band q22-q23. Six retinoid -responsive transcription factors have been identified so far, includi ng three retinoic acid receptors in addition to the three RXRs. Intere stingly, each of these receptors in human and mouse is encoded by gene s located at distinct chromosomal loci and on separate chromosomes. Th e proximity of RXR genes to loci known to be associated with genetic d isorders suggests that their location may be useful in establishing a link between RXRs and certain human diseases. (C) 1994 Academic Press, Inc.