Cloning of monkey RALDH1 and characterization of retinoid metabolism in monkey kidney proximal tubule cells.
All-trans and 9-cis retinoic acids function as ligands for retinoic acid receptors (RARs and RXRs), which are ligand-dependent transcription factors and play important roles in development and cellular differentiation. Several retinal dehydrogenases are likely to contribute to the production of all-trans and 9-cis RAs in vivo, but their respective roles in different tissues are still poorly characterized. We have previously characterized and cloned from kidney tissues the rat retinal dehydrogenase type 1 (RALDH1), which oxidizes all-trans and 9-cis retinal with high efficiency but is inactive with 13-cis retinal. Here we have characterized the retinal-oxidizing activity in monkey JTC12 cells, which are derived from kidney proximal tubules. In vitro assay of cell lysates revealed the presence of a NAD+-dependent dehydrogenase that catalyzed the oxidation of all-trans, 9-cis, and 13-cis retinal. Northern blot analysis of JTC12 RNAs and cloning by reverse transcription-polymerase chain reaction demonstrated expression of a monkey homolog of RALDH1. Bacterially expressed JTC12 RALDH1 catalyzed conversion of all three retinal isomers, with a higher catalytic efficiency for 9-cis retinal than for all-trans and 13-cis retinal. Accordingly, live JTC12 produced 9-cis retinoic acid more efficiently than all-trans retinoic acid from their respective retinal precursors. Only metabolites corresponding to the same steric conformation were formed from 9-cis or all-trans retinal, indicating a lack of detectable isomerizing activity in JTC12 cells.
Brodeur
Helene
H
Laboratory of Nutrition and Cancer, Universite de Montreal, Montreal, Quebec, Canada.
Gagnon
Isabelle
I
Mader
Sylvie
S
Bhat
Pangala V
PV
D000445:Aldehyde Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D004224:Diterpenes; D000882:Haplorhini; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007536:Isomerism; D015474:Isotretinoin / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000378:metabolism*; D008969:Molecular Sequence Data; D051381:Rats; D050697:Retinal Dehydrogenase; D012172:Retinaldehyde / Q000378:metabolism*; D016415:Sequence Alignment; D013379:Substrate Specificity; D014212:Tretinoin / Q000378:metabolism*
D004224:Diterpenes; C031390:9-cis-retinal; D014212:Tretinoin; D000445:Aldehyde Oxidoreductases; D050697:Retinal Dehydrogenase; D015474:Isotretinoin; D012172:Retinaldehyde