Dual-substrate Specificity Short Chain Retinol Dehydrogenases from the Vertebrate Retina

Abstract

Retinoids are chromophores involved in vision, transcriptional regulation, and cellular differentiation. Members of the short chain alcohol dehydrogenase/reductase superfamily catalyze the transformation of retinol to retinal. Here, we describe the identification and properties of three enzymes from a novel subfamily of four retinol dehydrogenases (RDH11-14) that display dualsubstrate specificity, uniquely metabolizing all-trans-and cis-retinols with C 15 pro-R specificity. RDH11-14 could be involved in the first step of all-trans-and 9-cis-retinoic acid production in many tissues. RDH11-14 fill the gap in our understanding of 11-cis-retinal and all-trans-retinal transformations in photoreceptor (RDH12) and retinal pigment epithelial cells (RDH11). The dualsubstrate specificity of RDH11 explains the minor phenotype associated with mutations in 11-cisretinol dehydrogenase (RDH5) causing fundus albipunctatus in humans and engineered mice lacking RDH5. Furthermore, photoreceptor RDH12 could be involved in the production of 11-cis-retinal from 11-cis-retinol during regeneration of the cone visual pigments. These newly identified enzymes add new elements to important retinoid metabolic pathways that have not been explained by previous genetic and biochemical studies.Retinoids are indispensable light-sensitive elements of vision and also serve as essential modulators of cellular differentiation and proliferation in diverse cell types, including those comprising the epithelium and immune system. Retinoids modulate the growth of both normal and malignant cells through their binding to retinoid receptors. All-trans-retinoic acid signals through specific interactions with the nuclear retinoic acid receptors, whereas its isomer, 9-cis-retinoic acid, is a high affinity ligand of retinoic acid receptors and retinoid X receptors. In the retina, light-dependent photoisomerization of 11-cis-retinylidene to the all-transretinylidene moiety of rod and cone photoreceptors is a key reaction that triggers visual * This research was supported by National Institutes of Health Grants EY08061, CA75173, and DK59125, a grant from Research to Prevent Blindness, Inc. (to the Department of Ophthalmology, University of Washington), and by the E. K. Bishop Foundation. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. S The on-line version of this article (available at http://www.jbc.org) contains Supplemental Figs. 1 and 2 and Tables 1-3. § These authors contributed equally to this work. § § Recipient of a Research to Prevent Blindness Senior Investigator Award. To whom correspondence should be addressed: Dept. of Ophthalmology, University of Washington, Seattle,; E-mail: palczews@u.washington.edu. Transformations of retinoids occur mostly through enzymatic or photochemical reactions, although they readily isomerize non-enzymatically to thermodynamic equilibriu...

Retinoid processing in cone and Müller cell lines

“…Our findings are in agreement with previously published reports whereby RDH11, RDH12, RDH14 and RetSDR1 are shown to specifically prefer the phosphorylated coenzyme, and catalyze the reduction over the oxidation reaction (Haeseleer, Huang, Lebioda, Saari and Palczewski, 1998;Rattner, Smallwood and Nathans, 2000). RDH13 has been shown before to completely lack catalytic activity towards retinoids (Haeseleer, Jang, Imanishi, Driessen, Matsumura, Nelson and Palczewski, 2002) therefore it is not expected to contribute to the total RDH activity measured here. Our results in Figure 3A also show a low NAD/NADH-dependent activity suggesting either the presence of other and unknown RDHs in the microsomal fraction of 661W cells or that the existing RDHs can also use NAD and NADH but at a much lower efficiency than NADP/NADPH.…”

RDH13L, an Enzyme Responsible for the Aldehyde-Alcohol Redox Coupling Reaction (AL-OL Coupling Reaction) to Supply 11-cis Retinal in the Carp Cone Retinoid Cycle

“…8A). However, it was previously reported that human RDH14 has NADPH-dependent 11-cis retinal reductase activity (27). From this result, we thought that mouse RDH14 may also have an activity to produce 11-cis retinal from its retinol in the absence of aldehydes but in the presence of added NADP ϩ .…”

“…7, recombinant RDH13L-His6 contains tightly bound NADP ϩ , not NADPH, at a molar ratio of almost 1:1 to RDH13L-His6. Other members of RDH family enzymes require exogenous NAD(H) or NADP(H) as a cofactor of the retinoid reduction/oxidation (27). Based on these findings, we propose that RDH13L catalyzes the AL-OL coupling using tightly bound NADP ϩ .…”

Lecithin-retinol Acyltransferase Is Essential for Accumulation of All-trans-Retinyl Esters in the Eye and in the Liver

“…After in-gel trypsin digestion, the eluted tryptic peptides were examined by microsequencing by liquid chromatography-mass spectrometry to verify the identity of the recombinant Lrat fragment. The purified protein was used to immunize mice as described before (23), and the monoclonal antibody was produced by established methods (24). The antibody was tested for its specificity by immunocytochemical testing of the Lratϩ/ϩ and LratϪ/Ϫ mouse retinas.…”