51
|
Gu SM, Thompson DA, Srikumari CR, Lorenz B, Finckh U, Nicoletti A, Murthy KR, Rathmann M, Kumaramanickavel G, Denton MJ, Gal A. Mutations in RPE65 cause autosomal recessive childhood-onset severe retinal dystrophy. Nat Genet 1997; 17:194-7. [PMID: 9326941 DOI: 10.1038/ng1097-194] [Citation(s) in RCA: 422] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Autosomal recessive childhood-onset severe retinal dystrophy (arCSRD) designates a heterogeneous group of disorders affecting rod and cone photoreceptors simultaneously. The most severe cases are termed Leber congenital amaurosis (LCA), while the less aggressive forms are usually considered juvenile retinitis pigmentosa. Recently, mutations in the retinal-specific guanylate cyclase gene were found in patients with LCA. Disease genes implicated in other forms of arCSRD are expected to encode proteins present in the neuroretina or in the retinal pigment epithelium (RPE). The RPE, a monolayer of cells separating the vascular-rich choroid and the neuroretina, is in intimate contact with the outer segments of rods and cones via the microvilli surrounding the photoreceptors. The RPE expresses a tissue-specific and evolutionarily highly conserved 61 kD protein (RPE65) present at high levels in vivo. Although the function of RPE65 is not yet known, an important role in the RPE/photoreceptor vitamin-A cycle is suggested by the fact that RPE65 associates both with serum retinol-binding protein and with the RPE-specific 11-cis retinol dehydrogenase, an enzyme active in the synthesis of the visual pigment chromophore 11-cis retinal. Here we report that the analysis of RPE65 in a collection of about 100 unselected retinal-dystrophy patients of different ethnic origin revealed five that are likely to be pathogenic mutations, including a missense mutation (Pro363Thr), two point mutations affecting splicing (912 + 1G-->T and 65 + 5G-->A) and two small re-arrangements (ins144T and 831del8) on a total of nine alleles of five patients with arCSRD. In contrast to other genes whose defects have been implicated in degenerative retinopathies, RPE65 is the first disease gene in this group of inherited disorders that is expressed exclusively in the RPE, and may play a role in vitamin-A metabolism of the retina.
Collapse
Affiliation(s)
- S M Gu
- Institut für Humangenetik, Universitäts-Krankenhaus Eppendorf, Hamburg, Germany
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
52
|
Tsilou E, Hamel CP, Yu S, Redmond TM. RPE65, the major retinal pigment epithelium microsomal membrane protein, associates with phospholipid liposomes. Arch Biochem Biophys 1997; 346:21-7. [PMID: 9328280 DOI: 10.1006/abbi.1997.0276] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The retinal pigment epithelium (RPE)-specific protein RPE65 is the major protein of the RPE microsomal membrane fraction. Though RPE65 lacks transmembrane domains or signal peptide, detergents are required for its maximally effective solubilization in isotonic buffers. However, in 0.75-1.0 M KCl, RPE65 is as soluble without detergent, indicating a peripheral membrane association. We wished to understand why this non-membrane-inserted protein was so closely associated with RPE microsomal membranes. To explore the possible involvement of interactions with phospholipids, an isotonic salt-soluble extract of RPE was incubated with phosphatidylcholine (PC)/phosphatidylserine (PS)/phosphatidylinositol liposomes and centrifuged to sediment the liposomes. RPE65 cosedimented with the liposome pellet. RPE65 also cosedimented with synthetic dipalmitoyl-, 1-palmitoyl, 2-docosahexaenoyl-PC or dipalmitoyl-PS liposomes. Incubation with 1 mM Ca2+ or 1 mM EGTA had no effect, indicating a Ca2+-independent association. A spectrophotometric assay showed that this interaction of RPE65 with phospholipid vesicles resulted in increased light scattering, consistent with phospholipid vesicle aggregation. Resonance energy transfer experiments showed that any putative aggregation occurred without subsequent vesicle fusion. This PC affinity was further confirmed by incubation of RPE extract with dimyristoyl-PC-immobilized artificial membrane (IAM.PC) matrix. The RPE65 selectively bound and was elutable with 2% detergent. This RPE65-phospholipid liposome association may explain the solubilization characteristics of RPE65 and may be related to the function of RPE65 and to its physical association with the RPE smooth endoplasmic reticulum.
Collapse
Affiliation(s)
- E Tsilou
- Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | | | |
Collapse
|
53
|
A membrane receptor for plasma Retinal-binding Protein (RBP) is expressed in the retinal pigment epithelium. Prog Retin Eye Res 1997. [DOI: 10.1016/s1350-9462(96)00020-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
54
|
Hodam JR, Creek KE. Uptake and metabolism of [3H]retinoic acid delivered to human foreskin keratinocytes either bound to serum albumin or added directly to the culture medium. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1311:102-10. [PMID: 8630327 DOI: 10.1016/0167-4889(95)00203-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Retinoic acid (RA), a potent modulator of cell proliferation and differentiation is present in plasma bound to serum albumin. The biologic significance or source of plasma RA is not clear. Although most cellular RA is believed to be made in situ via the oxidation of retinol, plasma RA could potentially provide target cells with a source of preformed RA. To investigate RA uptake, we have used a model system of human foreskin keratinocytes (HKc) cultured in serum-free media to compare the uptake and metabolism of [3H]RA added directly to the culture medium in ethanol to that delivered bound to bovine serum albumin (BSA). [3H]RA added directly to the culture medium was rapidly taken up by HKc during the first 10 min of incubation (25-35% of the applied RA), no further accumulation occurred between 10 min and 90 min, and then cell-associated radioactivity rapidly decreased to about 3-5% of the applied dose by 12 h. In contrast, when [3H]RA was delivered to HKc bound to BSA, total cell-associated radioactivity reached about 2.5% of the applied dose by 5 min, increased to 3-5% of the applied radioactivity by 1 h, and no further accumulation or loss occurred over the next 23 h. The uptake by HKc of [3H]RA delivered bound to BSA or added directly to the culture medium was not influenced by pre-treatment of the cells for 72 h with unlabeled RA or by excess unlabeled RA added at the time of uptake. Analysis of the cells and media by high-performance liquid chromatography for RA metabolites found that [3H]RA added directly to the medium is rapidly converted by HKc to polar compounds that are subsequently excreted back into the medium. Also, RA added directly to the medium was susceptible to degradation in the absence of cells. In marked contrast, [3H]RA added to the media bound to BSA was much less susceptible to degradation in the absence of cells, and few [3H]RA metabolites were found in the media even after exposure to HKc for 24 h. The binding of RA to albumin clearly protects RA from conversion to polar metabolites, and also provides for a controlled delivery of RA from the aqueous extracellular environment to the cell surface.
Collapse
Affiliation(s)
- J R Hodam
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia 29208, USA
| | | |
Collapse
|
55
|
Jaconi S, Rose K, Hughes G, Saurat J, Siegenthaler G. Characterization of two post-translationally processed forms of human serum retinol-binding protein: altered ratios in chronic renal failure. J Lipid Res 1995. [DOI: 10.1016/s0022-2275(20)41132-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
56
|
Okuno M, Caraveo VE, Goodman DS, Blaner WS. Regulation of adipocyte gene expression by retinoic acid and hormones: effects on the gene encoding cellular retinol-binding protein. J Lipid Res 1995. [DOI: 10.1016/s0022-2275(20)39762-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
57
|
Simon A, Hellman U, Wernstedt C, Eriksson U. The Retinal Pigment Epithelial-specific 11-cis Retinol Dehydrogenase Belongs to the Family of Short Chain Alcohol Dehydrogenases. J Biol Chem 1995. [DOI: 10.1074/jbc.270.3.1107] [Citation(s) in RCA: 200] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
|
58
|
Ylikoski J, Pirvola U, Eriksson U. Cellular retinol-binding protein type I is prominently and differentially expressed in the sensory epithelium of the rat cochlea and vestibular organs. J Comp Neurol 1994; 349:596-602. [PMID: 7860790 DOI: 10.1002/cne.903490407] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
To understand the possible role of retinoic acid during inner ear development and cellular regeneration, we have examined the expression pattern of two intracellular retinoid-binding proteins, the cellular retinol- and retinoic acid-binding proteins of type I in the developing and mature rat inner ear. Expression of cellular retinol-binding protein type I was seen in the supporting cells of the organ of Corti and vestibular organs as soon as the first signs of differentiation of the adjacent hair cells were seen. In the developing organ of Corti, the expression pattern followed the basal-to-apical coil differentiation gradient. After the 1st postnatal week, detectable expression of cellular retinol-binding protein type I disappeared from the organ of Corti, but persisted in the supporting cells of vestibular organs throughout life. Expression of cellular retinoic acid-binding protein type I was not found in the inner ear sensory epithelia. Cellular retinol-binding protein type I has previously been shown to act as a substrate carrier in the synthesis of retinoic acid from its precursor, retinol. Our data suggest that retinoic acid is synthesized in the developing sensory epithelium of the cochlear and vestibular organs and that a concentration gradient formed by retinoic acid may have a role in differentiation of the cochlear sensory epithelium. Furthermore, retinoic acid may have a role in damage-induced hair cell regeneration in the developing and mature vestibular organs as well as in the developing auditory organ. The absence of cellular retinol-binding protein type I from the supporting cells of the mature organ of Corti may be associated with the inability of this organ to regenerate hair cells after damage.
Collapse
Affiliation(s)
- J Ylikoski
- Department of Otolaryngology, University of Kuopio, Finland
| | | | | |
Collapse
|
59
|
Zetterström RH, Simon A, Giacobini MM, Eriksson U, Olson L. Localization of cellular retinoid-binding proteins suggests specific roles for retinoids in the adult central nervous system. Neuroscience 1994; 62:899-918. [PMID: 7870312 DOI: 10.1016/0306-4522(94)90482-0] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Retinoic acid, the active metabolite of retinoids (vitamin A compounds), is thought to act as a gene regulator via ligand-activated transcription factors. In order to investigate possible roles of retinoids and retinoid-controlled gene expression in brain function, we have used immunohistochemistry to localize the possible presence of two intracellular retinoid-binding proteins, cellular retinol-binding protein type I and cellular retinoic acid-binding protein type I, in the adult rat central nervous system. We find a widespread, yet distinct, presence of these two binding proteins in the brain and spinal cord. Most of the immunoreactivity is neuronal, including cell somata, as well as dendritic and axonal processes and axon terminals. Cellular retinol-binding protein type I-immunoreactivity is also found in the walls of cerebral blood vessels, the meninges, the choroid plexus, certain ependymal cells, tanocytes and certain other glial elements. The cellular retinol-binding protein type I- and cellular retinoic acid-binding protein type I-immunoreactivity patterns appear to be almost exclusively non-overlapping. Very strong cellular retinol-binding protein type I-immunoreactivity is found in the dendritic layers of the hippocampal formation and dentate gyrus. Cellular retinol-binding protein type I-immunoreactivity is also present in layer 5 cortical pyramidal neurons and neurons in the glomerular layer of the olfactory bulb. Many other areas, e.g. hypothalamic nuclei and amygdala areas, contain networks of varicose cellular retinol-binding protein type I-immunoreactive nerve fibers. The medial amygdaloid nucleus contains strongly cellular retinol-binding protein type I-positive neurons. Cellular retinoic acid-binding protein type I-immunoreactivity is more restricted in the adult brain. Strong cellular retinoic acid-binding protein type I-immunoreactivity is, however, found in a population of medium-sized neurons scattered throughout the striatum, in neurons in the glomerular layer of the olfactory bulb, the olfactory nerve and in a group of nerve cells close to the third ventricle in hypothalamus. The remarkably selective patterns of cellular retinol-binding protein type I- and cellular retinoic acid-binding protein type I-immunoreactivity discovered in the adult rat brain suggest that retinoids have important roles as regulators of gene expression in normal brain function. The high levels of cellular retinol-binding protein type I-immunoreactivity found in hippocampus suggest that one such role might relate to brain plasticity.
Collapse
Affiliation(s)
- R H Zetterström
- Department of Neuroscience, Karolinska Institute, Stockholm, Sweden
| | | | | | | | | |
Collapse
|
60
|
Sivakumar B, Jahoor F, Burrin DG, Frazer EM, Reeds PJ. Fractional synthesis rates of retinol-binding protein, transthyretin, and a new peptide measured by stable isotope techniques in neonatal pigs. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)47178-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
61
|
Vonesch JL, Nakshatri H, Philippe M, Chambon P, Dollé P. Stage and tissue-specific expression of the alcohol dehydrogenase 1 (Adh-1) gene during mouse development. Dev Dyn 1994; 199:199-213. [PMID: 8018987 DOI: 10.1002/aja.1001990305] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The Adh-1 gene product, ADH-A2, the only known murine class I alcohol dehydrogenase, is able to oxidize retinol (vitamin A) into retinaldehyde, the first enzymatic step in the conversion of retinol into its biologically active metabolite retinoic acid. We have investigated the developmental expression pattern of Adh-1 transcripts by in situ hybridization. Transcripts were first detected by embryonic day 10.5 in the mesonephros mesenchyme. During the following gestational days, Adh-1 transcripts were detected in several mesenchymal areas, such as nasal, laterocervical, and genital regions. Adh-1 transcripts were also detected in a small ectodermal domain at the anterior margins of both forelimbs and hindlimbs. During late fetal development. Adh-1 transcripts were found essentially in the epidermis and in a number of tissues which continue to express the gene after birth, such as liver, kidney, gut epithelium, adrenal cortex, testis interstitium, and ovarian stroma. In contrast, a strong expression of Adh-1 was found in the mesenchyme of developing lungs, but not in the adult organ. This highly regulated expression of Adh-1 is discussed with respect to the local synthesis of retinoic acid during development. Although the promoter of the human counterpart of Adh-1 contains a retinoic acid response element (Duester et al. [1991] Mol. Cell. Biol. 11:1638-1646), we report that this element is not conserved in the murine gene. Consistently, Adh-1 promoter-containing reporter constructs were not retinoic acid-inducible in cotransfections assays with RARs and/or RXRs, suggesting that retinoic acid regulation of Adh-1 differs from that of the human gene.
Collapse
Affiliation(s)
- J L Vonesch
- Laboratoire de Génétique Moléculaire des Eucaryotes du CNRS, Unité 184 de Biologie Moléculaire et de Génie Génétique de l'INSERUM, Faculté de Médecine, Strasbourg, France
| | | | | | | | | |
Collapse
|
62
|
Ong DE, Davis JT, O'Day WT, Bok D. Synthesis and secretion of retinol-binding protein and transthyretin by cultured retinal pigment epithelium. Biochemistry 1994; 33:1835-42. [PMID: 8110786 DOI: 10.1021/bi00173a029] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Recent studies indicate that the retinal pigment epithelium (RPE) may serve as an extrahepatic source of retinol-binding protein (RBP) and transthyretin (TTR) for the retina by virtue of the fact that this cell layer is the exclusive retinal location for mRNA coding for these proteins [Herbert, J., et al. (1991) Invest. Ophthalmol. Vis. Sci. 32, 302-309; Cavallaro, T., et al. (1990) Invest. Ophthalmol. Vis. Sci. 31, 497-501], although the proteins themselves are present in a variety of retinal neurons. It is therefore necessary to determine whether these mRNAs are translated and whether their translated products are secreted like hepatic RBP and TTR. Metabolic labeling of cultured bovine RPE with [35S]cysteine and [35S]methionine and subsequent analysis of newly synthesized proteins in the conditioned medium by affinity chromatography, gel filtration, partial amino acid sequence analysis, and autoradiography of electrophoretograms indicate that both RBP and TTR are synthesized and secreted by the RPE. Moreover, for cells grown in chambers with permeable supports, the predominant direction for secretion was into the apical medium. The mean apical:basal ratio after 72 h of incubation was 9.2 for TTR and 4.5 for RBP. A function for these proteins in the neurosensory retina remains speculative. They could be involved in the delivery of all-trans-retinol to amacrine and Müller cells as a precursor for retinoic acid, since these cells are known to contain cellular retinoic acid binding protein [Gaur, V.P., et al. (1990) Exp. Eye Res. 50, 505-511; Milam et al. (1990) J. Comp. Neurol. 296, 123-129].(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- D E Ong
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee 37232
| | | | | | | |
Collapse
|
63
|
Vieira AV, Schneider WJ. Transport and uptake of retinol during chicken oocyte growth. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1169:250-6. [PMID: 7548118 DOI: 10.1016/0005-2760(93)90248-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Most, if not all, components found in the yolk of a chicken egg are extracted from the plasma compartment during the rapid growth phase of the oocyte. Uptake of the major yolk constituents, very-low-density lipoprotein and vitellogenin, has been shown to be mediated by a specific receptor in the plasma membrane of the oocyte (Barber, D.L., Aebersold, R., Sanders, E.J. and Schneider, W.J. (1991) J. Biol. Chem. 266, 18761-18770). In the current study, we sought biochemical evidence for the uptake into oocytes of a minor but biologically very important component, the vitamin retinol. For transport in serum, retinol is bound to retinol-binding protein (RBP), which in turn forms a complex with transthyretin (TTR). In order to gain insight into the biochemical details of transport of the vitamin, we have identified, purified and characterized RBP, TTR, and RBP-TTR complexes from chicken serum and yolk. The results demonstrate that both serum and yolk contain the tertiary retinol-RBP-TTR complexes as well as free RBP and TTR. Western blots of yolk collected from oocytes at different stages of growth show that both RBP and TTR, but not albumin, are more abundant at early stages relative to total yolk protein. In addition, we find both RBP and TTR in endocytic clathrin-coated vesicles of the oocyte. Our results support the hypothesis that retinol, which must be imported by the oocyte for proper embryonic development, is internalized by the chicken oocyte bound to its serum protein-transport complex.
Collapse
Affiliation(s)
- A V Vieira
- Department of Biochemistry, University of Alberta, Edmonton, Canada
| | | |
Collapse
|
64
|
|
65
|
Båvik C, Lévy F, Hellman U, Wernstedt C, Eriksson U. The retinal pigment epithelial membrane receptor for plasma retinol-binding protein. Isolation and cDNA cloning of the 63-kDa protein. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(20)80759-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
66
|
Hamel C, Tsilou E, Pfeffer B, Hooks J, Detrick B, Redmond T. Molecular cloning and expression of RPE65, a novel retinal pigment epithelium-specific microsomal protein that is post-transcriptionally regulated in vitro. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)82319-5] [Citation(s) in RCA: 90] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
67
|
Hamel CP, Tsilou E, Harris E, Pfeffer BA, Hooks JJ, Detrick B, Redmond TM. A developmentally regulated microsomal protein specific for the pigment epithelium of the vertebrate retina. J Neurosci Res 1993; 34:414-25. [PMID: 8474143 DOI: 10.1002/jnr.490340406] [Citation(s) in RCA: 87] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In the vertebrate retina, the retinal pigment epithelium (RPE) performs specific functions critical to the normal process of vision. Although some of these functions are well documented, molecular data are still scarce. Using the RPE-specific monoclonal antibody RPE9, raised against human RPE cells, we have identified a novel 65 kD protein, conserved in mammals, birds, and frogs. This RPE-specific protein was found to be nonglycosylated. It was most effectively solubilized in the presence of detergent suggesting that it is associated with the RPE cell membranes. Its partitioning in the detergent phase of Triton X-114 and its solubilization in 0.75 M and 1.0 M KCl suggest that it interacts with the membrane either through a polypeptide anchor or charged amino acids. Cell fractionation by differential solubilization and differential centrifugation demonstrated that the protein was preferentially associated with the microsomal membrane fraction, where it is the major protein. Developmental expression of this 65 kD protein was examined in neonatal rats. Morphologically well-differentiated RPE cells did not express the 65 kD protein at birth. However, expression was detectable at postnatal day 4, that is, one to two days before the photoreceptors develop their outer segments, suggesting that the expression of the 65 kD protein may be coordinated with other developmental events in the intact retina. This is further supported by the fact that RPE cells in confluent culture lose the expression of this protein within two weeks, while they maintain their characteristic epithelial morphology. Because of its specificity, its evolutionary conservation, and its timing of expression, it is possible that this protein may be involved in one of the key roles of RPE and as such is an important molecular marker for RPE differentiation.
Collapse
Affiliation(s)
- C P Hamel
- Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, NIH, Bethesda, Maryland 20892
| | | | | | | | | | | | | |
Collapse
|
68
|
Zapponi MC, Zanotti G, Stoppini M, Berni R. The primary structure of piscine (Oncorhynchus mykiss) retinol-binding protein and a comparison with the three-dimensional structure of mammalian retinol-binding protein. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 210:937-43. [PMID: 1483476 DOI: 10.1111/j.1432-1033.1992.tb17498.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
1. The primary structures of two variants of rainbow trout (Oncorhynchus mykiss) plasma retinol-binding protein (RBP) were determined and found to be approximately 60% identical with those of both human and Xenopus laevis RBPs. The comparable sequence similarities that we have found agree with the estimate of similar divergence times between bony fishes and mammals and between bony fishes and amphibians. The two piscine RBP variants differ by six amino acid substitutions at positions that are not crucial for the interaction with retinol, on the basis of the human RBP three-dimensional structure [Cowan, S. W., Newcomer, M. E. & Jones, T. A. (1990) Proteins Struct. Func. Genet. 8, 44-61]. 2. Models were developed for the three-dimensional structures of rainbow trout and X. laevis RBPs, based on that of human RBP. The overall three-dimensional structure appears to be very well preserved for RBPs isolated from vertebrate species for which the divergence time is 350-400 million years. At variance with an almost absolute conservation for the residues that participate in the formation of the retinol binding site in mammalian RBPs, several amino acid replacements are found for this part of the RBP molecule when the comparison is extended to piscine and amphibian RBPs. However, the only allowed amino acid replacements are either conservative or more than 0.4 nm distant from retinol. Besides the retinol binding site, a few regions at the protein surface appear to be rather conserved during phylogenetic development of vertebrates and, therefore, might be involved in molecular interactions.
Collapse
Affiliation(s)
- M C Zapponi
- Dipartimento di Biochimica, Università di Pavia, Italy
| | | | | | | |
Collapse
|
69
|
Busch C, Siegenthaler G, Vahlquist A, Nordlinder H, Sundelin J, Saksena P, Eriksson U. Expression of cellular retinoid-binding proteins during normal and abnormal epidermal differentiation. J Invest Dermatol 1992; 99:795-802. [PMID: 1335015 DOI: 10.1111/1523-1747.ep12614757] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Retinoids have important roles in growth and differentiation of epidermal cells. We have analyzed the expression of two intracellular retinoid-binding proteins, the cellular retinol-binding protein type I and the cellular retinoic acid-binding protein type I, during normal and abnormal epidermal differentiation. Both proteins were found to be expressed in normal epidermis with increasing expression from basal layer towards superficial layers. In psoriatic lesions, a hyperproliferative condition of the skin, the epidermal expression of cellular retinol-binding protein I was induced, whereas expression of cellular retinoic acid-binding protein I was sharply down-regulated. This and other features of psoriatic lesions indicate that down-regulation of cellular retinoic acid-binding protein I expression might cause aberrant retinoid-regulated gene expression in skin. In basal and squamous cell carcinomas, cellular retinoic acid-binding protein I expression was down-regulated, whereas cellular retinol-binding protein I was expressed. Apart from epidermal cells, a mesenchymal, dendritic cell-type, strongly expressing cellular retinoic acid-binding protein I, was identified in the dermis. In several hyperproliferative conditions of the skin, including psoriasis, and squamous and basal cell carcinomas, this cell type was abundant. These results have implications for the role of retinoids in normal and abnormal epidermal differentiation and suggest that part of the phenotype of psoriasis is due to inappropriate metabolism of retinoic acid in skin.
Collapse
Affiliation(s)
- C Busch
- Department of Pathology, University Hospital, Uppsala, Sweden
| | | | | | | | | | | | | |
Collapse
|
70
|
Båvik C, Busch C, Eriksson U. Characterization of a plasma retinol-binding protein membrane receptor expressed in the retinal pigment epithelium. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)50052-1] [Citation(s) in RCA: 94] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
71
|
|
72
|
Creek KE, Hodam JR, St Hilaire P. REPLY. J Invest Dermatol 1992. [DOI: 10.1111/1523-1747.ep12616188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
73
|
Bychkova VE, Berni R, Rossi GL, Kutyshenko VP, Ptitsyn OB. Retinol-binding protein is in the molten globule state at low pH. Biochemistry 1992; 31:7566-71. [PMID: 1510943 DOI: 10.1021/bi00148a018] [Citation(s) in RCA: 111] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Using far- and near-UV circular dichroism, viscosity, tryptophan fluorescence, NMR spectra, binding of a hydrophobic probe, and microcalorimetry, we have shown that the apo form of human retinol-binding protein (RBP) at neutral pH is in a rigid state with properties similar to those of holo-RBP. On the contrary, at acidic pH apo-RBP is in the molten globule state which has been earlier revealed for a number of proteins under mild denaturing conditions. We have also shown that, at equilibrium, the pH-induced retinol release from holo-RBP parallels denaturation of the apoprotein. These findings are consistent with our hypothesis that the transformation of RBP into the molten globule state is involved in the mechanism whereby retinol is delivered to target cells. In particular, a local acidic pH near the membrane surface of target cells might cause the transition of RBP to the molten globule state as well as the release of retinol.
Collapse
Affiliation(s)
- V E Bychkova
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region
| | | | | | | | | |
Collapse
|
74
|
Berni R, Formelli F. In vitro interaction of fenretinide with plasma retinol-binding protein and its functional consequences. FEBS Lett 1992; 308:43-5. [PMID: 1386578 DOI: 10.1016/0014-5793(92)81046-o] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The synthetic retinoid fenretinide (4-HPR; N-[4-hydroxyphenyl] all-trans-retinamide) interacts with plasma apo-retinol-binding protein (RBP) to form a tight complex (K'd approximately 0.2 microM) which does not exhibit binding affinity to transthyretin (TTR). Therefore, a substantial modification of the retinol hydroxyl group does not appear to affect the interaction with RBP but does drastically interfere with the protein-protein recognition. The remarkable early reduction in plasma retinol level induced by fenretinide administration may be associated with the high binding affinity of this retinoid to RBP and to its interference with the RBP-TTR complex formation.
Collapse
Affiliation(s)
- R Berni
- Istituto di Scienze Biochimiche, Università di Parma, Italy
| | | |
Collapse
|