Retinoids have chemopreventive and therapeutic potency in oncology and dermatology, although their application is restricted by many undesirable side effects. For the development of more effective and less toxic retinoids, gene expression analyses using DNA microarrays have the potential to supplement conventional screening methods, which are based on the changes in cell morphology and/or funct...

Recent studies have suggested that the active metabolite of vitamin D3, 1,25-dihydroxyvitamin D3, can inhibit the growth and/or induce the differentiation of a variety of cell types and that these characteristics might be useful in the treatment of some cancers. Retinoids also promote the differentiation and inhibit the growth of some cells. That the vitamin D receptor acts as a heterodimer wit...

Retinoic acid exhibits effects on the proliferation and differentiation of many hematopoietic cells. Cellular responsiveness to retinoic acid (RA) is conferred through two distinct classes of nuclear receptors, the RA receptors (RARs) and the retinoid X receptors (RXRs). The RARs bind to both 9-cis- and all-trans-RAs, but 9-cis-RA alone directly binds and activates RXR. This suggested that 9-ci...

Retinoid X receptors (RXR) are members of the nuclear receptor superfamily of ligand-activated transcription factors that have been characterized in a wide variety of metazoan phyla. They act as heterodimer partners of other nuclear receptors, and in vertebrates also activate transcription as homodimers in the presence of a ligand, 9-cis retinoic acid. In order to test the hypothesis that retin...

Atherosclerosis is a major cause of morbidity and mortality in developed societies, and begins when activated endothelial cells recruit monocytes and T-cells from the bloodstream into the arterial wall. Macrophages that accumulate cholesterol and other fatty materials are transformed into foam cells. Several epidemiological studies have demonstrated that a diet rich in carotenoids is associated...

The mechanisms by which multipotent progenitor cells are directed to alternative cell identities during the histogenesis of the vertebrate central nervous system are likely to involve several different types of signaling systems. Recent evidence indicates that 9-cis retinoic acid, which acts through members of the steroid/thyroid superfamily of receptors, directs progenitor cells to the rod pho...

The results of several recent studies have demonstrated that cell commitment and differentiation in the developing vertebrate retina are influenced by cell-cell interactions within the microenvironment. Retinoic acid has been shown to influence cell fates during development of the nervous system, and retinoic acid has been detected in the embryonic retina. To determine whether retinoic acid med...

We report identification of 9-cis-4-oxo-retinoic acid (9-cis-4-oxo-RA) as an in vivo retinoid metabolite in Xenopus embryos. 9-Cis-4-oxo-RA bound receptors (RARs) alpha, beta, and gamma as well as retinoid X receptors (RXRs) alpha, beta, and gamma in vitro. However, this retinoid displayed differential RXR activation depending on the response pathway used. Although it failed to activate RXRs in...

Exposure to estrogens during the neonatal period interrupts rat prostatic development by reducing branching morphogenesis and by blocking epithelial cells from entering a normal differentiation pathway. Upon aging, ventral prostates exhibit extensive hyperplasia, dysplasia, and massive lymphocytic infiltrate, suggesting that neonatal estrogens may predispose the prostate gland to precancerous l...