Retinoid metabolism

The known beneficial effects of retinoids on malignancies are assumed to relate to retinoid receptor-mediated antipromoting and anti-initiating effects. The latter appeals to be influenced by interference of several xenobiotics with different steps of the retinoid metabolism in the target cell. Of the carotenoids, (3-carotene is the most potent retinol precursor, yet being... 

Ethanol also inhibits ADH-catalyzed retinol oxidation in vitro, and ethanol treatment of mouse embtyos has been demonstrated to reduce endogenous RA levels. The inhibition of cytosolic RolDH activity and stimulation of microsomal RolDH activity could explain ethanol-mediated vitamin A depletion, separate from ADH isoenzymes. Although the exact mechanism of inhibition of retinoid metabolism by ethanol is unclear, these observations are consistent with the finding that patients with alcoholic liver disease have depletedhepatic vitamin A reserves [review see [2]. 

Blomhoff, R and Blomhoff, HK, 2006. Overview of retinoid metabolism and function. J Neurobiol 66, 606-630. 

Ziouzenkova, O. and J. Plutzky. 2008. Retinoid metabolism and nuclear receptor responses New insights into coordinated regulation of the PPAR-RXR complex. FEBS Lett 582(1 ) 32—38. 

RGS9-1 is required for normal inactivation of mouse cone phototransduction. Mol. Vis. 7 71—78. McBee, J.K., Palczewski, K., Baehr, W., and Pepperberg, D.R. (2001). Confronting complexity the interlink of phototransduction and retinoid metabolism in the vertebrate retina. Prog. Retin. Eye Res. 20 469-529. 

Kedishvili NY, Stone CL, Popov KM, Chernoff EAG. Role of alcohol dehydrogenases in steroid and retinoid metabolism. In Weiner H, Lindahl R, Crabb DW, Flynn TG, eds. Enzymology and Molecular Biology of Carbonyl Metabolism 6. New York Plenum Press, 1996 321-329. 

Retinoids, metabolic and synthetic derivatives of vitamin A, have been shown to function as effective... 

The small intestine is a major site of retinoid metabolism, beginning with the oxidative... 

Previous reviews on retinoid metabolism and action have focused almost exclusively on studies with mammals16 30 31,J58.6o,62- 65,io4,io< Qur understanding of the retinoid system in fish has grown immensely over the past decade and while there are many similarities with what has been shown in mammals, some subtle differences exist. There is also growing evidence that the retinoid system of many vertebrates is sensitive to toxicant exposure. The effects of toxicants on the retinoid system in mammals have been previously reviewed68 93 108. Additionally, Rolland87 has summarized cases of retinoid and thyroid disruptions in wildlife that include information about retinoids in feral fish from polluted areas. 

Napoli, J.L. Retinoid binding-proteins redirect retinoid metabolism biosynthesis and metabolism of retinoic acid. Semin. Cell Dev. Biol. 8 403-415, 1997. 

Ross, A. Overview of retinoid metabolism. J. Nutr. 123 S346-S350, 1993. 

Creech Kraft, J. Juchau, M.R. Xenopus laevis A model system for the study of embryonic retinoid metabolism. III. Isomerization and metabolism of all-trares-retinoic acid and 9-cis-retinoic acid and their dysmorphogenic effects in embryos during neurulation. Drug Metab.Dispos., 1995, 23, 1058-1071... 

The only information presently available about the CYP26C1 gene is its existence in the human genome . Any suggestion of a role in retinoid metabolism is only speculatory at this time. 

Nishimura N, Yonemoto J, Miyabara Y, Fujii-Kuriyama Y, Tohyama C (2005) Altered thyroxin and retinoid metabolic response to 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin in aryl hydrocarbon receptor-null mice. Arch Toxicol 79 260-267... 

The potential clinical issues related to P450 26C1 have not been considered in detail but would involve issues with retinoids, i.e., lack of retinoid metabolism would lead to an overload of retinoid-induced problems. As mentioned above (Sect. 7.51.3), some possibihties exist with genetic variations in focal facial dermal dysplasia type VI and nonsyndromic bilateral and unilateral optic nerve aplasia. 

The exact mechanisms of voriconazole-associated photosensitivity are unknown, but inhibition of retinoid metabolism or a direct phototoxic effect of voriconazole or its N-oxide main metabolite, formed by the action of CYP2C19, has been implicated. There was no significant correlation between the incidence of photosensitivity and voriconazole serum concentrations in six children with allergic bronchopulmonary aspergillosis [3T]. In a retrospective study of 24 lung transplant recipients with cystic fibrosis who took voriconazole, heterozygous carriers of the CYP2C19 2 allele required lower maintenance doses than... 

Kim, Y. K., L. Wassef, S. Chung, et al. 2011. P-Carotene and Its Cleavage Enzyme P-Carotene-15,15 -Oxygenase (Cmol) Affect Retinoid Metabolism in Developing Tissues. Faseb J 25, no 5 1641-52. 

Napoli, J. L. 1999. Interactions of Retinoid Binding Proteins and Enzymes in Retinoid Metabolism. Biochem Biophys Acta 1440, no 2-3 139-62. 

Napoli, J. L. 2000. A Gene Knockont Corroborates the Integral Function of Cellular Retinol-Binding Protein in Retinoid Metabolism. NutrRev 58, no 8 230-6. 

Pares, X., J. Farres, N. KedishvUi, and G. Duester. 2008. Medium-Chain and Short-Chain Dehydrogenases/Reductases in Retinoid Metabolism. Cell Mol Life Sci 65, no 24 3936 9. 

Sima, A., Manolescu, D-C., and Bhat, P. V. 2011. Retinoids and retinoid-metabolic gene expression in mouse adipose tissues. Biochem Cell Biol 89 578-584. 

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