Retinoids and the Vitamin a Receptor STRA6 in Health and Disease

Retinoids are essential for all chordates. They comprise a diverse group of natural and synthetic compounds derived from vitamin A with differing configuration of double bonds, oxidation state and modifications. Retinoids may be beneficial or detrimental to health: they are known teratogens, but a dietary deficiency leads to numerous defects throughout the body, such as night blindness. They exert their effects through a multi-layered signalling network by acting as transcription factors for a number of genes aside from retinoid homeostasis. This diversity in retinoid signalling may be exploited for therapeutic purposes, such as fostering differentiation or eliminating malignant cells in certain cancers. This chapter focusses on the effects that retinoids have in health and disease and, particularly, the role of one component of their signalling pathway—the membrane bound receptor for retinol, STRA6. This unique transporter of vitamin A is itself implicated in several disease states and warrants further attention to open novel therapeutic avenues.