title: Retinaldehyde is a substrate for human aldo-keto reductases of the 1C subfamily.
abstract: Human AKR (aldo-keto reductase) 1C proteins (AKR1C1-AKR1C4) exhibit relevant activity with steroids, regulating hormone signalling at the pre-receptor level. In the present study, investigate the activity of the four human AKR1C enzymes with retinol and retinaldehyde. All of the enzymes except AKR1C2 showed retinaldehyde reductase activity with low Km values (~1 μM). The kcat values were also low (0.18-0.6 min-1), except for AKR1C3 reduction of 9-cis-retinaldehyde whose kcat was remarkably higher (13 min-1). Structural modelling of the AKR1C complexes with 9-cis-retinaldehyde indicated a distinct conformation of Trp227, caused by changes in residue 226 that may contribute to the activity differences observed. This was partially supported by the kinetics of the AKR1C3 R226P mutant. Retinol/retinaldehyde conversion, combined with the use of the inhibitor flufenamic acid, indicated a relevant role for endogenous AKR1Cs in retinaldehyde reduction in MCF-7 breast cancer cells. Overexpression of AKR1C proteins depleted RA (retinoic acid) transactivation in HeLa cells treated with retinol. Thus AKR1Cs may decrease RA levels in vivo. Finally, by using lithocholic acid as an AKR1C3 inhibitor and UVI2024 as an RA receptor antagonist, we provide evidence that the pro-proliferative action of AKR1C3 in HL-60 cells involves the RA signalling pathway and that this is in part due to the retinaldehyde reductase activity of AKR1C3.
authors.affiliation: Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Spain.
authors.forename: F Xavier
authors.initials: FX
authors.lastname: Ruiz
authors.forename: Sergio
authors.initials: S
authors.lastname: Porté
authors.forename: Oriol
authors.initials: O
authors.lastname: Gallego
authors.forename: Armando
authors.initials: A
authors.lastname: Moro
authors.forename: Albert
authors.initials: A
authors.lastname: Ardèvol
authors.forename: Alberto
authors.initials: A
authors.lastname: Del Río-Espínola
authors.forename: Carme
authors.initials: C
authors.lastname: Rovira
authors.forename: Jaume
authors.initials: J
authors.lastname: Farrés
authors.forename: Xavier
authors.initials: X
authors.lastname: Parés
mesh_terms: D015089:20-Hydroxysteroid Dehydrogenases / Q000737:chemistry / Q000378:metabolism*; D015096:3-Hydroxysteroid Dehydrogenases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000074425:Aldo-Keto Reductase Family 1 Member C3; D019943:Amino Acid Substitution; D001665:Binding Sites; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D006801:Humans; D006911:Hydroxyprostaglandin Dehydrogenases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006913:Hydroxysteroid Dehydrogenases / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D018168:Receptors, Retinoic Acid / Q000037:antagonists & inhibitors / Q000378:metabolism; D012172:Retinaldehyde / Q000737:chemistry* / Q000494:pharmacology / Q000502:physiology; D013379:Substrate Specificity; D015533:Transcriptional Activation; D014801:Vitamin A / Q000737:chemistry / Q000494:pharmacology / Q000502:physiology; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific)
chemical_list: D015089:20-Hydroxysteroid Dehydrogenases; D015096:3-Hydroxysteroid Dehydrogenases; D000074425:Aldo-Keto Reductase Family 1 Member C3; D006911:Hydroxyprostaglandin Dehydrogenases; D006913:Hydroxysteroid Dehydrogenases; D010088:Oxidoreductases; D018168:Receptors, Retinoic Acid; D012172:Retinaldehyde; D014801:Vitamin A; C115140:3 alpha-beta, 20 beta-hydroxysteroid dehydrogenase; C435496:AKR1C2 protein, human; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific); C487341:AKR1C3 protein, human; C048338:trans-1,2-dihydrobenzene-1,2-diol dehydrogenase