Liver Retinol Transporter and Receptor for Serum Retinol-binding Protein (RBP4)

Alapatt, Philomena; Guo, Fangjian; Komanetsky, Susan M.; Wang, Shuping; Cai, Jinjin; Sargsyan, Ashot; Díaz, E; Bacon, Brandon T.; Aryal, Pratik; Graham, Timothy E.

doi:10.1074/jbc.m112.369132

Cited by 123 publications

(193 citation statements)

References 70 publications

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“…It is possible that this protein has a role in intercellular retinol transfer within the liver. Interestingly, Alapatt et al report that RBPR2 shares considerable structural similarity with STRA6 ( 122 ). However, at present, these and other possibilities for explaining how retinol is transported between hepatocytes and HSCs remain to be established.…”

Section: Retinoids In Adipose Tissuementioning

confidence: 99%

“…Other early authors suggested that some unidentifi ed protein was involved in facilitating this process ( 6,7,88 ). In late 2012, Alapatt et al reported the identifi cation of a novel retinol transporter that is expressed primarily in mouse liver and intestine and that is able to bind RBP4 (this receptor is named RBP4 receptor-2 or RBPR2) ( 122 ). It is possible that this protein has a role in intercellular retinol transfer within the liver.…”

Section: Retinoids In Adipose Tissuementioning

confidence: 99%

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Retinol and retinyl esters: biochemistry and physiology

O’Byrne

Blaner

2013

Journal of Lipid Research

311

250

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The different retinoid forms present within the body (see Fig. 1 ) are generated by and large through modifi cations to the terminal polar end group of the molecule. Retinol and retinyl esters are the most abundant retinoid forms present in the body. All-trans -retinol is by defi nition vitamin A. When a fatty acyl group is esterifi ed to the hydroxyl terminus of retinol, a storage form of retinol, the retinyl ester, is formed. The most abundant retinyl esters present in the body are those of palmitic acid, oleic acid, stearic acid, and linoleic acid ( 6, 7 ). Although retinyl acetate can be found in supplements to foods and vitamin formulations, only long-chain acyl groups are esterifi ed to retinol by animals. Retinyl esters have no known biological activity aside from retinol storage and for serving as the substrate for the formation of the visual chromophore 11-cis -retinal, which must be formed from all-trans -retinyl ester through linked hydrolysis and isomerization reactions catalyzed by the enzyme RPE65 ( 3,4,8,9 ). Retinol is a transport form and a precursor form, which is enzymatically activated to retinoic acid via a two-step oxidation process. The primary role of retinal is in the eye where 11-cis -retinal is needed for visual pigment formation. In tissues, retinal serves as an intermediate in the synthesis of retinoic acid from retinol ( 6, 7 ). The literature also suggests a direct role for retinal in adipose tissue, where it was shown to inhibit adipogenesis and suppress peroxisome proliferator-activated receptor-␥ (PPAR ␥ ) and retinoid X receptor (RXR) responses in cell culture models and in mouse models fed high-fat diets ( 10 ).Abstract By defi nition, a vitamin is a substance that must be obtained regularly from the diet. Vitamin A must be acquired from the diet, but unlike most vitamins, it can also be stored within the body in relatively high levels. For humans living in developed nations or animals living in present-day vivariums, stored vitamin A concentrations can become relatively high, reaching levels that can protect against the adverse effects of insuffi cient vitamin A dietary intake for six months, or even much longer. The ability to accumulate vitamin A stores lessens the need for routinely consuming vitamin A in the diet, and this provides a selective advantage to the organism. The molecular processes that underlie this selective advantage include effi cient mechanisms to acquire vitamin A from the diet, effi cient and overlapping mechanisms for the transport of vitamin A in the circulation, a specifi c mechanism allowing for vitamin A storage, and a mechanism for mobilizing vitamin A from these stores in response to tissue needs. These processes are considered in this review. Since the identifi cation of fat-soluble A a century ago ( 1 ), retinoids (vitamin A and its natural and synthetic analogs) have been the most extensively studied of the fatsoluble vitamins. This research has identifi ed essential roles for retinoids in many different aspects of mammalian physiology, includ...

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Section: Retinoids In Adipose Tissuementioning

confidence: 99%

Section: Retinoids In Adipose Tissuementioning

confidence: 99%

Retinol and retinyl esters: biochemistry and physiology

O’Byrne

Blaner

2013

Journal of Lipid Research

311

250

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“…3 and 175 ). STRA6, the plasma membrane receptor for retinol carrier RBP4, is known to be induced by atRA in extrahepatic tissues ( 173,174 ) while retinolbinding protein receptor 2 (RBPR2), the recently discovered analogous receptor in rodent liver, is suppressed by atRA, presumably to promote the uptake of retinol by extrahepatic tissues under conditions of vitamin A sufficiency ( 176 ).…”

Section: Feedback Regulation By Atramentioning

confidence: 99%

Enzymology of retinoic acid biosynthesis and degradation

Kedishvili

2013

Journal of Lipid Research

170

165

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This article is available online at http://www.jlr.org ( 10 ), and regulation of energy homeostasis ( 11,12 ). atRA exerts its actions by serving as an activating ligand of nuclear atRA receptors [retinoid acid receptor (RAR) ␣ , RAR ␤ , and RAR ␥ ] and peroxisome proliferator-activated receptors (PPAR) ␤ / ␦ , which form heterodimers with retinoid X receptors ( 13,14 ). The actions of the RARs are described in more detail in this thematic series by RochetteEgly and colleagues. The concentration of atRA during embryonic development is tightly controlled in a spatial and temporal manner, and in adult tissues, it is maintained within a very narrow range that is specifi c for each given tissue. If the control mechanisms fail and the concentration of atRA exceeds or falls below the optimal range, tissues and cells undergo pathophysiological changes that in most severe cases can lead to disease. Thus, the maintenance of optimal atRA levels is essential for life. This review focusses on recent fi ndings regarding the mechanisms that control atRA homeostasis, with specifi c emphasis on the enzymes involved in atRA biosynthesis and degradation. All-trans -retinoic acid (atRA) is a highly potent derivative of vitamin A that is required for virtually all essential physiological processes and functions because of its involvement in transcriptional regulation of over 530 different genes ( 1, 2 ). For example, atRA is necessary for differentiation and development of fetal and adult tissues, stem cell differentiation, and apoptosis ( 3-7 ), and for support of reproductive functions ( 8, 9 ), immune response

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“…These observations initiated studies leading to the identification of the novel RBP4 receptor-2 (RBPR2) in 2013 [162]. Polymorphisms in RBPR2 have not been investigated so far.…”

Section: Stimulated By Retinoic Acid 6 (Stra6)mentioning

confidence: 99%

Genetic Determination of Serum Levels of Diabetes-Associated Adipokines

Schleinitz

2015

Rev Diabet Stud

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■ AbstractAdipose tissue secretes an abundance of proteins. Some of these proteins are known as adipokines and adipose-derived hormones which have been linked with metabolic disorders, including type 2 diabetes, and even with cancer. Variance in serum adipokine concentration is often closely associated with an increase (obesity) or decrease (lipodystrophy) in fat tissue mass, and it is affected by age, gender, and localization of the adipose tissue. However, there may be genetic variants which, in consequence, influence the serum concentration of a certain adipokine, and thereby promote metabolic disturbances or, with regard to the "protective" allele, exert beneficial effects. This review focuses on the genetic determination of serum levels of the following adipokines: adiponectin, chemerin, leptin, progranulin, resistin, retinol binding protein 4, vaspin, adipsin, apelin, and omentin. The article reports on the latest findings from genome-wide association studies (GWAS) and candidate gene studies, showing variants located in/nearby the adipokine genes and other (non-receptor) genes. An extra chapter highlights adipokine-receptor variants. Epigenetic studies on adipokines are also addressed.

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Liver Retinol Transporter and Receptor for Serum Retinol-binding Protein (RBP4)

Cited by 123 publications

References 70 publications

Retinol and retinyl esters: biochemistry and physiology

Retinol and retinyl esters: biochemistry and physiology

Enzymology of retinoic acid biosynthesis and degradation

Genetic Determination of Serum Levels of Diabetes-Associated Adipokines

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