Cellular retinoid-binding proteins

Ong, D. E.

doi:10.1001/archderm.123.12.1693

Cited by 45 publications

(85 citation statements)

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“…High levels of CRABP I are evident in embryonic tissues with a high susceptibility to the teratogenic action of RA [3,5,18], which include the eye [41] and cerebellum [42]. RA-binding proteins sequester free RA and maintain its availability for enzymatic inactivation [43]. CRABP-I-rich tissues respond to RA [25,36] but are likely also to require protection from inappropriate levels of free RA.…”

Section: Discussionmentioning

confidence: 99%

Retinoid‐binding proteins in the cerebellum and choroid plexus and their relationship to regionalized retinoic acid synthesis and degradation

Yamamoto

Dräger

Ong

et al. 1998

European Journal of Biochemistry

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The expression of cellular retinoic-acid-binding protein (CRABP) and cellular retinol-binding protein (CRBP), as well as their relationship to retinoic acid (RA) synthesis and degradation were examined in the developing mouse cerebellum and choroid plexus of the fourth ventricle. The choroid plexus, which expresses the RA-synthesizing retinaldehyde dehydrogenase RALDH-2, is likely to represent a diffusion source of RA for the closely apposed cerebellum, regulating its development. We found CRBP to be expressed in the choroid plexus and, in an in-vitro assay, addition of recombinant CRBP to RALDH-2 increased RA synthesis from retinaldehyde, with the amount of increase depending on the CRBP/retinaldehyde ratio. A technique that characterizes RA-binding proteins according to their isoelectric point showed both CRABP I and CRABP II to be present in the cerebellum and P19 cells, and only CRABP II to be present in the choroid plexus. With this technique, CRABP I could also be detected in the HL60 cell line. In addition to the two known acidic RA-binding proteins CRABP I and II, the cerebellum expressed a third RA-binding protein distinguishable by its neutral isoelectric point; the same binding protein was also detected in the olfactory bulb, kidney and testes. We used the RA-binding technique to follow the rate of elimination of bound RA from the cerebellum. A systemic injection of 0.3 µmols RA into postnatal day-1 mice was almost completely removed after 8 hours. These results suggest mechanisms by which the retinoid-binding protein may regulate the equilibrium of RA synthesis and catabolism in the cerebellum and choroid plexus.

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Section: Discussionmentioning

confidence: 99%

Retinoid‐binding proteins in the cerebellum and choroid plexus and their relationship to regionalized retinoic acid synthesis and degradation

Yamamoto

Dräger

Ong

et al. 1998

European Journal of Biochemistry

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“…Both passive [8] and active [9,10] mechanisms of β-carotene uptake into enterocytes have been suggested. Upon entering the enterocyte, provitamin A carotenoids like β-carotene can be cleaved by β-carotene 15,15′-monooxygenase (BCMO1) to retinal and the resulting retinal can bind one of cellular retinolbinding proteins, type II (RBP2, also known as CRBP II) [11]. Retinal bound to RBP2 (retinal-RBP2) is then acted upon by retinal reductase and reduced to retinol which also binds to RBP2.…”

mentioning

confidence: 99%

“…The product of LRAT action, retinyl ester, is incorporated into chylomicrons along with the other dietary lipids before secretion into the lymphatic system. Similar β-carotene conversion processes to vitamin A occur in other retinoid target tissues, except in those tissues, cellular binding protein, type I (RBP1, also known as CRBP I) will take place of type II, as latter is only expressed in intestine while former is expressed ubiquitously [11]. The enzymes that are involved in this pathway have been studied individually.…”

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confidence: 99%

In vitro and in vivo characterization of retinoid synthesis from β-carotene

Fierce

Vieira

Piantedosi

et al. 2008

Archives of Biochemistry and Biophysics

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Retinoids are indispensable for the health of mammals, which cannot synthesize retinoids de novo. Retinoids are derived from dietary provitamin A carotenoids, like β-carotene, through the actions β-carotene 15,15′ monooxygenase (BCMO1). As the substrates for retinoid metabolizing enzymes are water insoluble, they must be transported intracellularly bound to cellular retinol-binding proteins. Our studies suggest that cellular retinol binding protein, type I (RBP1) acts as an intracellular sensor of retinoid status that, when present as apo-RBP1, stimulates BCMO1 activity and the conversion of carotenoids to retinoids. Cellular retinol binding protein, type II (RBP2), which is 56% identical to RBP1 does not influence BCMO1 activity. Studies of mice lacking BCMO1 demonstrate that BCMO1 is responsible for metabolically limiting the amount of intact β-carotene that can be absorbed by mice from their diet. Our studies provide new insights into the regulation of BCMO1 activity and the physiological role of BCMO1 in living organisms. Keywordsβ-carotene; cleavage; β-carotene 15; 15′ monooxygenase; retinoid; metabolism; cellular retinol binding protein Retinoids (vitamin A, its natural metabolites and synthetic analogs) are required for survival of mammals and are needed to support vision, normal cell differentiation and proliferation, embryonic development, normal immune function and reproduction [1]. Aside from in vision, all of the essential actions of retinoids within the body are thought to involve the transcriptional activity of retinoic acid [1]. Retinoic acid is a potent transcriptional regulator whose effects are mediated by two families of nuclear receptors, the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs) [2][3][4]. When retinoic acid is not available, RAR/RXR heterodimers bind to retinoic acid response elements in promoter of genes and form complexes with transcriptional corepressors resulting in chromatin condensation and transcriptional silencing. In the presence of retinoic acid, corepressors are released from the RAR/RXR heterodimer which is now free to recruit and bind coactivators resulting in chromatin *Corresponding author: Jisun Paik, Department of Comparative Medicine, Raitt Hall, 324, Seattle, WA 98195. Phone: 206-221-2682; Fax: 206-685-1696; E-mail: jpaik@u.washington.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript decondensation and transcriptional activation. In excess of 500 genes may be responsive to retinoic acid [5].Since ani...

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“…RA is derived from vitamin A (retinol), which circulates complexed to retinol-binding protein (RBP) and transthyretin (Ttr; Soprano and Blaner 1994). RBP receptors mediate retinol uptake into cells (Bavik et al 1995), where it is then bound to cellular RBPs (CRBP I, II; Ong et al 1994). Conversion of retinol into active RA is a multistep process requiring retinol dehydrogenases (RoDH) and Raldhs (Clagett-Dame and DeLuca 2002).…”

mentioning

confidence: 99%

Signaling hierarchy downstream of retinoic acid that independently regulates vascular remodeling and endothelial cell proliferation

Bohnsack¹,

Lai²,

Dollé³

et al. 2004

Genes Dev.

103

128

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We previously demonstrated that during vascular morphogenesis, retinoic acid (RA) is required for the control of endothelial cell proliferation and capillary plexus remodeling. Herein, we investigate the mechanisms by which RA regulates these processes in the yolk sac. We found that although the enzyme required for RA production during early embryogenesis, retinaldehyde dehydrogenase-2 (Raldh2), was expressed in the visceral endoderm, RA receptors ␣1 and ␣2 were expressed in endothelial cells in the mesoderm, indicating that they are direct targets of RA. In Raldh2 −/− embryos, there was down-regulation of TGF-␤1, fibronectin (Fn) and integrin ␣5, which was associated with decreased visceral endoderm survival and production of VEGF-A, Indian hedgehog (IHH), and bFGF. Exogenous provision of RA or Fn to Raldh2 −/− explants in whole mouse embryo culture restored vascular remodeling, visceral endoderm survival, as well as integrin ␣5 expression and its downstream signaling that controls endothelial growth. Exogenous provision of visceral endoderm-derived factors (VEGF-A, IHH, and bFGF) failed to rescue endothelial cell proliferative control but collectively promoted vascular remodeling, suggesting that these processes are independently regulated via a signaling hierarchy downstream of RA.

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Cellular retinoid-binding proteins

Cited by 45 publications

References 0 publications

Retinoid‐binding proteins in the cerebellum and choroid plexus and their relationship to regionalized retinoic acid synthesis and degradation

Retinoid‐binding proteins in the cerebellum and choroid plexus and their relationship to regionalized retinoic acid synthesis and degradation

In vitro and in vivo characterization of retinoid synthesis from β-carotene

Signaling hierarchy downstream of retinoic acid that independently regulates vascular remodeling and endothelial cell proliferation

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