Cloning of a cDNA for Liver Microsomal Retinol Dehydrogenase
A TISSUE-SPECIFIC, SHORT-CHAIN ALCOHOL DEHYDROGENASE (*)
- From the Department of Biochemistry, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York 14214
- § To whom correspondence should be addressed: School of Medicine and Biomedical Sciences, 140 Farber Hall, SUNY-Buffalo, Buffalo, NY 14214. Tel.: 716-829-2726; Fax: 716-829-2725.
Abstract
Retinoic acid, a hormone biosynthesized from retinol, controls numerous biological systems by regulating eukaryotic gene expression
from conception through death. This work reports the cloning and expression of a liver cDNA encoding a microsomal retinol
dehydrogenase (RoDH), which catalyzes the primary and rate-limiting step in retinoic acid synthesis. The predicted amino acid
sequence and biochemical data obtained from the recombinant enzyme verify it as a short-chain alcohol dehydrogenase. Like
microsomal RoDH, the recombinant enzyme recognized as substrate retinol bound to cellular retinol-binding protein, had higher
activity with NADP rather than NAD, was stimulated by ethanol or phosphatidylcholine, was not inhibited by 4-methylpyrazole,
was inhibited by phenylarsine oxide and carbenoxolone and localized to microsomes. RoDH recognized the physiological form
of retinol, holocellular retinol-binding protein, with a K
of 0.9 μM, a value lower than the 
5 μM concentration of holocellular retinol binding protein in liver. Northern and Western blot analyses revealed RoDH expression
only in rat liver, despite enzymatic activity in liver, brain, kidney, lung, and testes. These data suggest that tissue-specific
isozyme(s) of short chain alcohol dehydrogenases catalyze the first step in retinoic acid biogenesis and further strengthen
the evidence that the “cassette” of retinol bound to cellular retinol-binding protein serves as a physiological substrate.
Footnotes
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↵* This work was supported by National Institutes of Health Grant DK36870. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵1 The abbreviations used are:
- RA
-
all-trans-retinoic acid
- CRBP
-
cellular retinol-binding protein, type I
- PAO
-
phenylarsine oxide
- PCR
-
polymerase chain reaction
- SCAD
-
short-chain alcohol dehydrogenase.
-
2M. H. E. M. Boerman and J. L. Napoli, unpublished results.
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- Received October 28, 1994.
- Revision received December 9, 1994.
- © 1995 by The American Society for Biochemistry and Molecular Biology, Inc.
