Structures of cellular retinoic acid binding proteins I and II in complex with synthetic retinoids

1999 ◽  
Vol 55 (11) ◽  
pp. 1850-1857 ◽  
Author(s):  
Barnali Neel Chaudhuri ◽  
Gerard J. Kleywegt ◽  
Isabelle Broutin-L'Hermite ◽  
Terese Bergfors ◽  
Hans Senn ◽  
...  

Retinoids play important roles in diverse cellular processes including growth, cell differentiation and vision. Many natural and synthetic retinoids are used as drugs in dermatology and oncology. A large amount of data has been accumulated on the cellular activity of different synthetic retinoids. They are stabilized and transported inside the cell cytoplasm by binding and transport proteins, such as cellular retinol-binding proteins and cellular retinoic acid binding proteins (CRABPs). The structures of human CRABP II in complex with two different synthetic retinoids, Ro13-6307 and Ro12-7310 (at 2.1 and 2.0 Å resolution, respectively) and of bovine CRABP I in complex with a retinobenzoic acid, Am80 (at 2.8 Å resolution) are described. The binding affinities of human CRABP I and II for the retinoids studied here have been determined. All these compounds have comparable binding affinities (nanomolar range) for both CRABPs. Apart from the particular interactions of the carboxylate group of the retinoids with specific protein groups, each structure reveals characteristic interactions. Studying the atomic details of the interaction of retinoids with retinoid-binding proteins facilitates the understanding of the kinetics of retinoid trafficking inside the cytoplasm.

Development ◽  
1993 ◽  
Vol 118 (1) ◽  
pp. 267-282 ◽  
Author(s):  
E. Ruberte ◽  
V. Friederich ◽  
P. Chambon ◽  
G. Morriss-Kay

We have studied the transcript distribution of the retinoic acid receptors (RARs) and the cytoplasmic retinoid binding proteins during embryonic development of the mouse nervous system. Of the three retinoic acid receptors, only RAR-gamma was not expressed in developing neural structures. RAR-beta and RAR-alpha both showed rostral limits of expression in the medulla oblongata equivalent to their patterns of expression in the neuroepithelium of the early hindbrain neural tube. Within their expression domains in the spinal cord and brain, RAR-alpha was ubiquitously expressed, whereas RAR-beta transcripts showed very specific patterns of expression, suggesting that this receptor is involved in mediating retinoic acid-induced gene expression in relation to the development of specific neural structures or pathways. The cytoplasmic binding proteins, cellular retinoic acid binding proteins type I and II (CRABP I and CRABP II) and cellular retinol binding protein type I (CRBP I), were widely distributed in developing neural structures. Their differential spatiotemporal patterns of expression suggest that fine regional control of availability of retinoic acid (RA) to the nuclear receptors plays an important role in organization and differentiation of the nervous system. For instance, expression of CRABP I in the migrating cells that give rise to the olivary and pontine nuclei, which develop abnormally in conditions of retinoid excess, is consistent with observations from a variety of other systems indicating that CRABP I limits the access of RA to the nuclear receptors in normal physiological conditions. Similarly, expression of CRBP I in the choroid plexuses, which develop abnormally in conditions of vitamin A deficiency, is consistent with observations indicating that this binding protein mediates the synthesis of RA in tissues requiring high levels of RA for their normal developmental programme. RAR-beta and CRABP II, which are both RA-inducible, were coexpressed with CRBP I in the choroid plexus and in many other sites, perhaps reflecting the fact that all three genes are RA-inducible. The function of CRABP II is not well understood; its domains of expression showed overlaps with both CRABP I and CRBP I.


2011 ◽  
Vol 58 (1) ◽  
Author(s):  
Emilia Stachurska ◽  
Agnieszka Loboda ◽  
Justyna Niderla-Bielińska ◽  
Małgorzata Szperl ◽  
Michał Juszyński ◽  
...  

Cellular retinoic acid binding proteins are considered to be involved in retinoic acid (RA) signaling pathways. Our aim was to compare the expression and localization of cellular retinoic acid binding proteins I and II (CRABP I and II) in embryonic mouse hearts during normal development and after a single teratogenic dose of RA. Techniques such as real-time PCR, RT-PCR, Western blots and immunostaining were employed to examine hearts from embryos at 9-17 dpc. RA treatment at 8.5dpc affects production of CRABP I and II in the heart in the 48-h period. Changes in expression of mRNA for retinaldehyde dehydrogenase II (Raldh2), Crabp1 and Crabp2 genes also occur within the same time window (i.e. 10-11dpc) after RA treatment. In the embryonic control heart these proteins are localized in groups of cells within the outflow tract (OT), and the atrioventricular endocardial cushions. A gradient of labeling is observed with CRABP II but not for CRABP I along the myocardium of the looped heart at 11 dpc; this gradient is abolished in hearts treated with RA, whereas an increase of RALDH2 staining has been observed at 10 dpc in RA-treated hearts. Some populations of endocardial endothelial cells were intensively stained with anti-CRABP II whereas CRABP I was negative in these structures. These results suggest that CRABP I and II are independently regulated during heart development, playing different roles in RA signaling, essential for early remodeling of the heart tube and alignment of the great arteries to their respective ventricles.


2002 ◽  
Vol 22 (14) ◽  
pp. 5114-5127 ◽  
Author(s):  
Nguan-Soon Tan ◽  
Natacha S. Shaw ◽  
Nicolas Vinckenbosch ◽  
Peng Liu ◽  
Rubina Yasmin ◽  
...  

ABSTRACT Lipophilic compounds such as retinoic acid and long-chain fatty acids regulate gene transcription by activating nuclear receptors such as retinoic acid receptors (RARs) and peroxisome proliferator-activated receptors (PPARs). These compounds also bind in cells to members of the family of intracellular lipid binding proteins, which includes cellular retinoic acid-binding proteins (CRABPs) and fatty acid binding proteins (FABPs). We previously reported that CRABP-II enhances the transcriptional activity of RAR by directly targeting retinoic acid to the receptor. Here, potential functional cooperation between FABPs and PPARs in regulating the transcriptional activities of their common ligands was investigated. We show that adipocyte FABP and keratinocyte FABP (A-FABP and K-FABP, respectively) selectively enhance the activities of PPARγ and PPARβ, respectively, and that these FABPs massively relocate to the nucleus in response to selective ligands for the PPAR isotype which they activate. We show further that A-FABP and K-FABP interact directly with PPARγ and PPARβ and that they do so in a receptor- and ligand-selective manner. Finally, the data demonstrate that the presence of high levels of K-FABP in keratinocytes is essential for PPARβ-mediated induction of differentiation of these cells. Taken together, the data establish that A-FABP and K-FABP govern the transcriptional activities of their ligands by targeting them to cognate PPARs in the nucleus, thereby enabling PPARs to exert their biological functions.


1988 ◽  
Vol 249 (3) ◽  
pp. 929-932 ◽  
Author(s):  
B P Sani ◽  
A Vaid

Specific cellular binding proteins for retinol and retinoic acid from mammalian and avian species may mediate the action of retinoids in the control of epithelial differentiation, growth and tumorigenesis. Parasite retinol-binding protein (PRBP) and parasite retinoic acid-binding protein (PRABP) isolated and characterized from parasitic worms of the family Filarioidea might be involved in some possible action of vitamin A compounds in these parasites. Ivermectin, a potent and widely used anti-parasitic drug, competes efficiently with retinol for retinol-binding sites on PRBP, but not for the host-tissue retinol-binding-protein sites. The drug has no affinity for retinoic acid-binding proteins from either parasite or host tissues. Binding studies using radiolabelled ivermectin and retinol reveal that ivermectin has a higher affinity than retinol for PRBP. A correlation exists between the binding affinities of ivermectin analogues and their anti-parasitic activities. A binding-protein-mediated interrelationship may exist between the actions of retinol and ivermectin in the parasites, but not in the host tissues.


1991 ◽  
Vol 115 (3) ◽  
pp. 851-859 ◽  
Author(s):  
J Buck ◽  
A Myc ◽  
A Garbe ◽  
G Cathomas

We have previously reported on the dependency of activated B lymphocytes for retinol. Here we confirm and extend these findings that cells deprived of retinol perish in cell culture within days, displaying neither signs of apoptosis nor of cell cycle arrest. Cell death can be prevented by physiological concentrations of retinol and retinal, but not by retinoic acid or three synthetic retinoic acid analogues. To exclude the possibility that retinoic acid is so rapidly degraded as to escape detection, we have tested its stability in intra- and extracellular compartments. Contrary to expectation, we find that retinoic acid persists for longer (t 1/2 3 d) in cultures than retinol (t 1/2 1 d). Furthermore, despite the use of sensitive trace-labeling techniques, we cannot detect retinoic acid or 3,4-didehydroretinoic acid among retinol metabolites. However, retinol is converted into several new retinoids, one of which has the ability to sustain B cell growth in the absence of an external source of retinol, supporting the notion of a second retinol pathway. We have also determined which of the known retinoid-binding proteins are expressed in B lymphoblastoid cells. According to results obtained with polymerase chain reaction-assisted mRNA detection, they transcribe the genes for cellular retinol- and cellular retinoic acid-binding proteins, for the nuclear retinoic acid receptors, RAR-alpha, -gamma, and RXR-alpha, but not RAR-beta. Our findings that B cells do not synthesize retinoic acid or respond to exogenous retinoic acid on the one hand, but on the other hand convert retinol to a novel bioactive form of retinol, suggest the existence of a second retinoid pathway, distinct from that of retinoic acids.


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