Vitamin A has both positive and negative regulatory functions in the immune system. While vitamin A is required for normal formation of immune cells and epithelial cell barriers, vitamin A deficiency can lead to increased inflammatory responses and tissue damage. The mechanism with which vitamin A and its metabolites such as retinoids negatively regulate inflammatory responses has not been clea...

Steroid and xenobiotic receptor (SXR) or human pregnane X receptor (hPXR) dimerizes with retinoid X receptor (RXR) and regulates the transcription of genes encoding xenobiotic-metabolizing enzymes such as CYP3A4. Rifampin, the classical activator of CYP3A4, binds to SXR directly. It is unclear whether various natural and synthetic retinoids can regulate the expression of CYP3A4. To evaluate the...

Solid organ transplant recipients (OTRs) have an increased incidence of skin cancer, resulting in significant morbidity and mortality post-transplantation. Chemoprevention strategies are focused on reducing and delaying the development of skin cancer in these patients. Although systemic retinoids are widely used in OTRs, few randomized controlled trials have been performed. Limited data suggest...

Vitamin A (retinol), its natural and synthetic derivatives, and its metabolites are known collectively as retinoids (Fig. 1). Vitamin A is required in the diets of vertebrate animals, and vitamin A is oxidized to RA,2 a compound that exerts dramatic effects on vertebrate development and cell differentiation. In addition, retinoids can inhibit or reverse the process of malignant transformation i...

When I began studying biochemistry at the Graduate School of Pharmaceutical Sciences at the University of Tokyo, Japan, molecular cloning of retinoic acid receptors (RARs), the nuclear receptors for retinoids, was one of the hottest topics in medical science. In the laboratory of Professor Koichi Shudo, who was my mentor and now my current manager, the development of novel synthetic retinoids h...

BACKGROUND Retinoids are lipophilic isoprenoids composed of a cyclic group and a linear chain with a hydrophilic end group. These compounds include retinol, retinal, retinoic acid, retinyl esters, and various derivatives of these structures. Retinoids are used as cosmetic agents and effective pharmaceuticals for skin diseases. Retinal, an immediate precursor of retinoids, is derived by β-carote...