Nuclear and extranuclear effects of vitamin A1

• Published in: Canadian journal of physiology and pharmacology 2015, Vol.93 (12), p.1065-1075
• Main Authors: Iskakova, Madina, Karbyshev, Mikhail, Piskunov, Aleksandr, Rochette-Egly, Cécile
• Format: Article
• Language: English
• Subjects: acide rétinoïque; phosphorylation; retinoic acid; signaling; signalisation; transcription; vitamin A; vitamine A
• ISSN: 0008-4212; 1205-7541
• DOI: 10.1139/cjpp-2014-0522

Vitamin A or retinol is a multifunctional vitamin that is essential at all stages of life from embryogenesis to adulthood. Up to now, it has been accepted that the effects of vitamin A are exerted by active metabolites, the major ones being 11-cis retinal for vision, and all trans-retinoic acid (RA) for cell growth and differentiation. Basically RA binds nuclear receptors, RARs, which regulate the expression of a battery of target genes in a ligand dependent manner. During the last decade, new scenarios have been discovered, providing a rationale for the understanding of other long-noted but not explained functions of retinol. These novel scenarios involve: (i) other nuclear receptors such as PPAR β/δ, which regulate the expression of other target genes with other functions; (ii) extranuclear and nontranscriptional effects, such as the activation of kinases, which phosphorylate RARs and other transcription factors, thus expanding the list of the RA-activated genes; (iii) finally, vitamin A is active per se and can work as a cytokine that regulates gene transcription by activating STRA6. New effects of vitamin A and RA are continuously being discovered in new fields, revealing new targets and new mechanisms thus improving the understanding the pleiotropicity of their effects.