Base de dados : MEDLINE
Pesquisa : D08.811.913.050.646 [Categoria DeCS]
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[PMID]:25944104
[Au] Autor:Campos B; Weisang S; Osswald F; Ali R; Sedlmeier G; Bageritz J; Mallm JP; Hartmann C; von Deimling A; Popanda O; Goidts V; Plass C; Unterberg A; Schmezer P; Burhenne J; Herold-Mende C
[Ad] Endereço:Experimental Neurosurgery, Department of Neurosurgery, University of Heidelberg, Heidelberg, Germany.
[Ti] Título:Retinoid resistance and multifaceted impairment of retinoic acid synthesis in glioblastoma.
[So] Source:Glia;63(10):1850-9, 2015 Oct.
[Is] ISSN:1098-1136
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Measuring concentrations of the differentiation-promoting hormone retinoic acid (RA) in glioblastoma tissues would help to understand the reason why RA treatment has been inefficient in clinical trials involving brain tumor patients. Here, we apply a recently established extraction and measurement protocol to screen glioblastoma tissues for the levels of the RA precursor retinol and biologically active RA. Combining this approach with mRNA analyses of 26 tumors and 8 normal brains, we identify a multifaceted disturbance of RA synthesis in glioblastoma, involving multiple aldehyde dehydrogenase 1 family and retinol dehydrogenase enzymes. Through database studies and methylation analyses, we narrow down chromosomal deletions and aberrant promoter hypermethylation as potential mechanisms accounting for these alterations. Employing chromatin immunoprecipitation analyses and cell-culture studies, we further show that chromatin at RA target genes is poised to RA substitution, but most glioblastoma cell cultures are completely resistant to RA treatment. This paradoxical RA response is unrelated to alternative RA signaling through the fatty acid-binding protein 5/peroxisome proliferator-activated receptor delta axis. Our data suggest a multifaceted disturbance of RA synthesis in glioblastoma and contribute to reconsider current RA treatment strategies.
[Mh] Termos MeSH primário: Neoplasias Encefálicas/complicações
Encéfalo/metabolismo
Regulação Neoplásica da Expressão Gênica/fisiologia
Glioblastoma/complicações
Tretinoína/metabolismo
[Mh] Termos MeSH secundário: Encéfalo/efeitos dos fármacos
Proliferação Celular/efeitos dos fármacos
Imunoprecipitação da Cromatina
Metilação de DNA
Bases de Dados Bibliográficas/estatística & dados numéricos
Inibidores Enzimáticos/farmacologia
Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos
Seres Humanos
Isoenzimas/metabolismo
Receptores do Ácido Retinoico/genética
Receptores do Ácido Retinoico/metabolismo
Retinal Desidrogenase/metabolismo
Retinoides/farmacologia
Retinol O-Graxo-Aciltransferase/metabolismo
Transdução de Sinais/efeitos dos fármacos
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Enzyme Inhibitors); 0 (Isoenzymes); 0 (Receptors, Retinoic Acid); 0 (Retinoids); 0 (retinoic acid receptor beta); 5688UTC01R (Tretinoin); EC 1.2.1.- (aldehyde dehydrogenase 1); EC 1.2.1.36 (Retinal Dehydrogenase); EC 2.3.1.76 (Retinol O-Fatty-Acyltransferase)
[Em] Mês de entrada:1605
[Cu] Atualização por classe:150811
[Lr] Data última revisão:
150811
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:150507
[St] Status:MEDLINE
[do] DOI:10.1002/glia.22849


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[PMID]:25383759
[Au] Autor:Golczak M; Sears AE; Kiser PD; Palczewski K
[Ad] Endereço:Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA.
[Ti] Título:LRAT-specific domain facilitates vitamin A metabolism by domain swapping in HRASLS3.
[So] Source:Nat Chem Biol;11(1):26-32, 2015 Jan.
[Is] ISSN:1552-4469
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Cellular uptake of vitamin A, production of visual chromophore and triglyceride homeostasis in adipocytes depend on two representatives of the vertebrate N1pC/P60 protein family, lecithin:retinol acyltransferase (LRAT) and HRAS-like tumor suppressor 3 (HRASLS3). Both proteins function as lipid-metabolizing enzymes but differ in their substrate preferences and dominant catalytic activity. The mechanism of this catalytic diversity is not understood. Here, by using a gain-of-function approach, we identified a specific sequence responsible for the substrate specificity of N1pC/P60 proteins. A 2.2-Å crystal structure of the HRASLS3-LRAT chimeric enzyme in a thioester catalytic intermediate state revealed a major structural rearrangement accompanied by three-dimensional domain swapping dimerization not observed in native HRASLS proteins. Structural changes affecting the active site environment contributed to slower hydrolysis of the catalytic intermediate, supporting efficient acyl transfer. These findings reveal structural adaptation that facilitates selective catalysis and mechanism responsible for diverse substrate specificity within the LRAT-like enzyme family.
[Mh] Termos MeSH primário: Aciltransferases/metabolismo
Fosfolipases A2 Independentes de Cálcio/metabolismo
Proteínas Supressoras de Tumor/metabolismo
Vitamina A/metabolismo
[Mh] Termos MeSH secundário: Animais
Seres Humanos
Camundongos
Camundongos Transgênicos
Modelos Moleculares
Conformação Proteica
Retinol O-Graxo-Aciltransferase/metabolismo
Especificidade por Substrato
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL; RESEARCH SUPPORT, NON-U.S. GOV'T; RESEARCH SUPPORT, U.S. GOV'T, NON-P.H.S.
[Nm] Nome de substância:
0 (Tumor Suppressor Proteins); 11103-57-4 (Vitamin A); EC 2.3.- (Acyltransferases); EC 2.3.1.- (lecithin-retinol acyltransferase); EC 2.3.1.76 (Retinol O-Fatty-Acyltransferase); EC 3.1.1.4 (PLA2G16 protein, human); EC 3.1.1.4 (Phospholipases A2, Calcium-Independent)
[Em] Mês de entrada:1502
[Cu] Atualização por classe:170604
[Lr] Data última revisão:
170604
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:141111
[St] Status:MEDLINE
[do] DOI:10.1038/nchembio.1687


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[PMID]:24799687
[Au] Autor:Kaylor JJ; Cook JD; Makshanoff J; Bischoff N; Yong J; Travis GH
[Ad] Endereço:Jules Stein Eye Institute and.
[Ti] Título:Identification of the 11-cis-specific retinyl-ester synthase in retinal Müller cells as multifunctional O-acyltransferase (MFAT).
[So] Source:Proc Natl Acad Sci U S A;111(20):7302-7, 2014 May 20.
[Is] ISSN:1091-6490
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Absorption of a photon by a rhodopsin or cone-opsin pigment isomerizes its 11-cis-retinaldehyde (11-cis-RAL) chromophore to all-trans-retinaldehyde (all-trans-RAL), which dissociates after a brief period of activation. Light sensitivity is restored to the resulting apo-opsin when it recombines with another 11-cis-RAL. Conversion of all-trans-RAL to 11-cis-RAL is carried out by an enzyme pathway called the visual cycle in cells of the retinal pigment epithelium. A second visual cycle is present in Müller cells of the retina. The retinol isomerase for this noncanonical pathway is dihydroceramide desaturase (DES1), which catalyzes equilibrium isomerization of retinol. Because 11-cis-retinol (11-cis-ROL) constitutes only a small fraction of total retinols in an equilibrium mixture, a subsequent step involving selective removal of 11-cis-ROL is required to drive synthesis of 11-cis-retinoids for production of visual chromophore. Selective esterification of 11-cis-ROL is one possibility. Crude homogenates of chicken retinas rapidly convert all-trans-ROL to 11-cis-retinyl esters (11-cis-REs) with minimal formation of other retinyl-ester isomers. This enzymatic activity implies the existence of an 11-cis-specific retinyl-ester synthase in Müller cells. Here, we evaluated multifunctional O-acyltransferase (MFAT) as a candidate for this 11-cis-RE-synthase. MFAT exhibited much higher catalytic efficiency as a synthase of 11-cis-REs versus other retinyl-ester isomers. Further, we show that MFAT is expressed in Müller cells. Finally, homogenates of cells coexpressing DES1 and MFAT catalyzed the conversion of all-trans-ROL to 11-cis-RP, similar to what we observed with chicken-retina homogenates. MFAT is therefore an excellent candidate for the retinyl-ester synthase that cooperates with DES1 to drive synthesis of 11-cis-retinoids by mass action.
[Mh] Termos MeSH primário: Acetiltransferases/metabolismo
Células Ependimogliais/enzimologia
Enzimas Multifuncionais/metabolismo
Retinol O-Graxo-Aciltransferase/metabolismo
[Mh] Termos MeSH secundário: Animais
Catálise
Bovinos
Galinhas
Opsinas dos Cones/metabolismo
Ésteres/química
Ácidos Graxos/química
Perfilação da Expressão Gênica
Regulação Enzimológica da Expressão Gênica
Células HEK293
Seres Humanos
Cinética
Camundongos
Opsinas/metabolismo
Retina/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL
[Nm] Nome de substância:
0 (Cone Opsins); 0 (Esters); 0 (Fatty Acids); 0 (Multifunctional Enzymes); 0 (Opsins); EC 2.3.1.- (Acetyltransferases); EC 2.3.1.76 (Retinol O-Fatty-Acyltransferase)
[Em] Mês de entrada:1407
[Cu] Atualização por classe:161019
[Lr] Data última revisão:
161019
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:140507
[St] Status:MEDLINE
[do] DOI:10.1073/pnas.1319142111


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[PMID]:24186946
[Au] Autor:Wongsiriroj N; Jiang H; Piantedosi R; Yang KJ; Kluwe J; Schwabe RF; Ginsberg H; Goldberg IJ; Blaner WS
[Ad] Endereço:Institute of Human Nutrition, Columbia University, New York, NY 10032.
[Ti] Título:Genetic dissection of retinoid esterification and accumulation in the liver and adipose tissue.
[So] Source:J Lipid Res;55(1):104-14, 2014 Jan.
[Is] ISSN:1539-7262
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Approximately 80-90% of all retinoids in the body are stored as retinyl esters (REs) in the liver. Adipose tissue also contributes significantly to RE storage. The present studies, employing genetic and nutritional interventions, explored factors that are responsible for regulating RE accumulation in the liver and adipose tissue and how these influence levels of retinoic acid (RA) and RA-responsive gene expression. Our data establish that acyl-CoA:retinol acyltransferase (ARAT) activity is not involved in RE synthesis in the liver, even when mice are nutritionally stressed by feeding a 25-fold excess retinol diet or upon ablation of cellular retinol-binding protein type I (CRBPI), which is proposed to limit retinol availability to ARATs. Unlike the liver, where lecithin:retinol acyltransferase (LRAT) is responsible for all RE synthesis, this is not true for adipose tissue where Lrat-deficient mice display significantly elevated RE concentrations. However, when CrbpI is also absent, RE levels resemble wild-type levels, suggesting a role for CrbpI in RE accumulation in adipose tissue. Although expression of several RA-responsive genes is elevated in Lrat-deficient liver, employing a sensitive liquid chromatography tandem mass spectrometry protocol and contrary to what has been assumed for many years, we did not detect elevated concentrations of all-trans-RA. The elevated RA-responsive gene expression was associated with elevated hepatic triglyceride levels and decreased expression of Pparδ and its downstream Pdk4 target, suggesting a role for RA in these processes in vivo.
[Mh] Termos MeSH primário: Tecido Adiposo Branco/metabolismo
Fígado/metabolismo
Retinoides/metabolismo
[Mh] Termos MeSH secundário: Animais
Epididimo/metabolismo
Esterificação
Ésteres
Feminino
Expressão Gênica
Regulação da Expressão Gênica
Masculino
Camundongos
Camundongos Endogâmicos C57BL
Camundongos Knockout
PPAR delta/metabolismo
Fosfatidilcolina-Esterol O-Aciltransferase/genética
Fosfatidilcolina-Esterol O-Aciltransferase/metabolismo
Proteínas Serina-Treonina Quinases/metabolismo
Retinol O-Graxo-Aciltransferase/genética
Retinol O-Graxo-Aciltransferase/metabolismo
Proteínas Celulares de Ligação ao Retinol/genética
Proteínas Celulares de Ligação ao Retinol/metabolismo
Triglicerídeos/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL
[Nm] Nome de substância:
0 (CrbpI protein, mouse); 0 (Esters); 0 (PPAR delta); 0 (Retinoids); 0 (Retinol-Binding Proteins, Cellular); 0 (Triglycerides); EC 2.3.1.43 (Phosphatidylcholine-Sterol O-Acyltransferase); EC 2.3.1.76 (Retinol O-Fatty-Acyltransferase); EC 2.7.11.1 (Protein-Serine-Threonine Kinases); EC 2.7.11.2 (pyruvate dehydrogenase (acetyl-transferring) kinase)
[Em] Mês de entrada:1407
[Cu] Atualização por classe:161025
[Lr] Data última revisão:
161025
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:131105
[St] Status:MEDLINE
[do] DOI:10.1194/jlr.M043844


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[PMID]:22634428
[Au] Autor:Betts BS; Obregon I; Tsin AT
[Ti] Título:Cultured Müller cells from mammals can synthesize and accumulate retinyl esters.
[So] Source:Exp Eye Res;101:56-9, 2012 Aug.
[Is] ISSN:1096-0007
[Cp] País de publicação:England
[La] Idioma:eng
[Mh] Termos MeSH primário: Neuroglia/metabolismo
Retinaldeído/síntese química
Retinol O-Graxo-Aciltransferase/metabolismo
Proteínas Celulares de Ligação ao Retinol/síntese química
Vitamina A/biossíntese
[Mh] Termos MeSH secundário: Animais
Bovinos
Células Cultivadas
Galinhas
Cromatografia Líquida de Alta Pressão
Ésteres/metabolismo
Seres Humanos
Camundongos
Camundongos Endogâmicos C57BL
Ratos
[Pt] Tipo de publicação:LETTER; RESEARCH SUPPORT, N.I.H., EXTRAMURAL; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Esters); 0 (Retinol-Binding Proteins, Cellular); 11103-57-4 (Vitamin A); EC 2.3.1.76 (Retinol O-Fatty-Acyltransferase); RR725D715M (Retinaldehyde)
[Em] Mês de entrada:1210
[Cu] Atualização por classe:161019
[Lr] Data última revisão:
161019
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:120529
[St] Status:MEDLINE
[do] DOI:10.1016/j.exer.2012.05.004


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[PMID]:19181555
[Au] Autor:Gao JG; Shih A; Gruber R; Schmuth M; Simon M
[Ad] Endereço:Department of Oral Biology and Pathology, School of Dental Medicine, Stony Brook University, Stony Brook, NY 11794-8702, USA. Jiaguo.Gao@stonybrook.edu
[Ti] Título:GS2 as a retinol transacylase and as a catalytic dyad independent regulator of retinylester accretion.
[So] Source:Mol Genet Metab;96(4):253-60, 2009 Apr.
[Is] ISSN:1096-7206
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:GS2 (PNPLA4; iPLAeta) is the smallest member of the patatin-like family of phospholipases (PNPLA). It was initially identified by its ability to hydrolyze retinylesters (RE) in cell homogenates, and was later found to esterify retinol using a variety of acyl donors. In the present study we set out to determine its cellular function and examined its impact on RE status in 293T cells transfected with GS2, GS2-M1 (a non-translatable mutant of GS2) and empty vector, in fibroblasts isolated from normal and GS2-null donors and in SCC12b and in a somatic cell knock-out of GS2 (SCC12b-GS2(neo/-)), that we generated by homologous recombination. At 50nM medium retinol, GS2 had no significant impact on RE accumulation. However, at 2muM retinol, GS2 promoted a 1.6- to 5-fold increase in RE accumulation. To verify role of GS2 as a catalyst, RE levels were measured in 293T transfected wild type GS2, catalytic dyad mutants devoid of enzymatic activity, or alanine substitution mutants spanning the entire GS2 sequence. Surprisingly, every GS2 mutant promoted RE accumulation. This activity was also observed in the GS2 paralogues and rat orthologue. The data demonstrate that within the context of the cell GS2 promotes RE accumulation and may do so either as a catalyst or as a regulatory protein that enhances RE formation catalyzed by other acyl transferases.
[Mh] Termos MeSH primário: Biocatálise
Ésteres/metabolismo
Proteínas/metabolismo
Retinol O-Graxo-Aciltransferase/metabolismo
Tretinoína/análogos & derivados
[Mh] Termos MeSH secundário: Aciltransferases/metabolismo
Substituição de Aminoácidos
Animais
Linhagem Celular
Esterificação
Éxons/genética
Fibroblastos/enzimologia
Fibroblastos/patologia
Regulação Enzimológica da Expressão Gênica
Técnicas de Inativação de Genes
Seres Humanos
Lipase
Camundongos
Proteínas/genética
RNA Mensageiro/genética
RNA Mensageiro/metabolismo
Ratos
Recombinação Genética/genética
Deleção de Sequência
Tretinoína/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Esters); 0 (Proteins); 0 (RNA, Messenger); 5688UTC01R (Tretinoin); EC 2.3.- (Acyltransferases); EC 2.3.1.- (lecithin-retinol acyltransferase); EC 2.3.1.76 (Retinol O-Fatty-Acyltransferase); EC 3.1.1.3 (Lipase); EC 3.1.1.3 (PNPLA4 protein, human)
[Em] Mês de entrada:0905
[Cu] Atualização por classe:131121
[Lr] Data última revisão:
131121
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:090203
[St] Status:MEDLINE
[do] DOI:10.1016/j.ymgme.2008.12.007


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[PMID]:19028692
[Au] Autor:Shih MY; Kane MA; Zhou P; Yen CL; Streeper RS; Napoli JL; Farese RV
[Ad] Endereço:Gladstone Institute of Cardiovascular Disease, San Francisco, California 94158, USA.
[Ti] Título:Retinol Esterification by DGAT1 Is Essential for Retinoid Homeostasis in Murine Skin.
[So] Source:J Biol Chem;284(7):4292-9, 2009 Feb 13.
[Is] ISSN:0021-9258
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Retinoic acid (RA) is a potent signaling molecule that is essential for many biological processes, and its levels are tightly regulated by mechanisms that are only partially understood. The synthesis of RA from its precursor retinol (vitamin A) is an important regulatory mechanism. Therefore, the esterification of retinol with fatty acyl moieties to generate retinyl esters, the main storage form of retinol, may also regulate RA levels. Here we show that the neutral lipid synthesis enzyme acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) functions as the major acyl-CoA:retinol acyltransferase (ARAT) in murine skin. When dietary retinol is abundant, DGAT1 deficiency results in elevated levels of RA in skin and cyclical hair loss; both are prevented by dietary retinol deprivation. Further, DGAT1-deficient skin exhibits enhanced sensitivity to topically administered retinol. Deletion of the enzyme specifically in the epidermis causes alopecia, indicating that the regulation of RA homeostasis by DGAT1 is autonomous in the epidermis. These findings show that DGAT1 functions as an ARAT in the skin, where it acts to maintain retinoid homeostasis and prevent retinoid toxicity. Our findings may have implications for human skin or hair disorders treated with agents that modulate RA signaling.
[Mh] Termos MeSH primário: Diacilglicerol O-Aciltransferase/metabolismo
Epiderme/enzimologia
Homeostase/fisiologia
Retinol O-Graxo-Aciltransferase/metabolismo
Tretinoína/metabolismo
[Mh] Termos MeSH secundário: Alopecia/enzimologia
Alopecia/genética
Animais
Diacilglicerol O-Aciltransferase/genética
Feminino
Homeostase/efeitos dos fármacos
Masculino
Camundongos
Camundongos Knockout
Retinoides/genética
Retinoides/metabolismo
Retinol O-Graxo-Aciltransferase/genética
Transdução de Sinais/efeitos dos fármacos
Transdução de Sinais/fisiologia
Tretinoína/farmacologia
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL
[Nm] Nome de substância:
0 (Retinoids); 5688UTC01R (Tretinoin); EC 2.3.1.20 (Dgat1 protein, mouse); EC 2.3.1.20 (Diacylglycerol O-Acyltransferase); EC 2.3.1.76 (Retinol O-Fatty-Acyltransferase)
[Em] Mês de entrada:0903
[Cu] Atualização por classe:161019
[Lr] Data última revisão:
161019
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:081126
[St] Status:MEDLINE
[do] DOI:10.1074/jbc.M807503200


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[PMID]:18163989
[Au] Autor:Kanan Y; Kasus-Jacobi A; Moiseyev G; Sawyer K; Ma JX; Al-Ubaidi MR
[Ad] Endereço:Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
[Ti] Título:Retinoid processing in cone and Müller cell lines.
[So] Source:Exp Eye Res;86(2):344-54, 2008 Feb.
[Is] ISSN:0014-4835
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:To determine whether cones and Müller cells in the rod dominated retina cooperate to regenerate the 11-cis retinal chromophore via the retinoid cycle, two cell lines from the rod dominated retinas of Murine were used for this study: 661W, a mouse cell line derived from cones, and rMC-1, a rat Müller cell line. Retinoid cycle enzymes were analyzed by RT-PCR, and their catalytic activity was detected by incubation with retinoids and analyzed by HPLC. We found that 661W cells are capable of reducing all-trans retinal to all-trans retinol due to the presence of multiple dehydrogenases and to generate minor amounts of retinyl-ester. The rMC-1 cells take up all-trans retinol and oxidize it to all-trans retinal or esterify it to retinyl-ester, but are incapable of isomerizing all-trans retinoids to 11-cis retinoids. This could be a reflection of lack of necessary activities in Müller cells in vivo, which suggests that Müller cells do not contribute to retinoid cycling by regenerating 11-cis retinoids. Alternatively, this could be due to the potential that rMC-1, as a transformed cell line, has stopped expressing the proteins needed for the regeneration of 11-cis retinoids.
[Mh] Termos MeSH primário: Retina/metabolismo
Retinoides/metabolismo
[Mh] Termos MeSH secundário: Animais
Linhagem Celular
Cromatografia Líquida de Alta Pressão/métodos
Ésteres/metabolismo
Camundongos
Camundongos Endogâmicos C57BL
Oxirredução
Oxirredutases/fisiologia
Fosfatidilcolina-Esterol O-Aciltransferase/metabolismo
Estimulação Luminosa
Células Fotorreceptoras Retinianas Cones/metabolismo
Retinaldeído/metabolismo
Retinol O-Graxo-Aciltransferase/metabolismo
Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos
Vitamina A/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Esters); 0 (Retinoids); 11103-57-4 (Vitamin A); EC 1.- (Oxidoreductases); EC 2.3.1.43 (Phosphatidylcholine-Sterol O-Acyltransferase); EC 2.3.1.76 (Retinol O-Fatty-Acyltransferase); RR725D715M (Retinaldehyde)
[Em] Mês de entrada:0804
[Cu] Atualização por classe:161122
[Lr] Data última revisão:
161122
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:080101
[St] Status:MEDLINE
[do] DOI:10.1016/j.exer.2007.11.006


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[PMID]:17014079
[Au] Autor:Muniz A; Villazana-Espinoza ET; Thackeray B; Tsin AT
[Ad] Endereço:Department of Biology, University of Texas at San Antonio, San Antonio, Texas 78249, USA.
[Ti] Título:11-cis-Acyl-CoA:retinol O-acyltransferase activity in the primary culture of chicken Muller cells.
[So] Source:Biochemistry;45(40):12265-73, 2006 Oct 10.
[Is] ISSN:0006-2960
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:A novel retinoid cycle has recently been identified in the cone-dominated chicken retina, and this cone cycle accumulates 11-cis-retinyl esters upon light adaptation. The purpose of this study is to investigate how 11-cis-retinyl esters are formed in the retina. Primary cultures of chicken Muller cells and cell membrane were incubated with all-trans- or 11-cis-retinol to study retinyl ester synthesis. In Muller cells, esterification of 11-cis-retinol was four times greater than esterification of all-trans-retinol. In the presence of palmitoyl-CoA and CRALBP, Muller cell membranes synthesized 11-cis-retinyl ester from 11-cis-retinol at a rate which was 20-fold higher than that of all-trans-retinyl ester. In the absence of CRALBP, 11-cis-retinyl ester synthesis was greatly reduced (by 7-fold). In the absence of palmitoyl-CoA, retinyl ester synthesis was not observed. Muller cell membranes incubated with radiolabeled palmitoyl-CoA resulted in the transfer of the labeled acyl group to retinol. This acyl transfer was greatly reduced in the presence of progesterone, a known ARAT inhibitor. 11-cis-ARAT activity remained unchanged when assayed in the presence of all-trans-retinol, suggesting a distinct catalytic activity from that of all-trans-ARAT. Apparent kinetic rates for 11-cis-ARAT were 0.135 nmol min(-)(1) mg(-)(1) (V(max)) and 11.25 microM (K(M)) and for all-trans-ARAT were 0.0065 nmol min(-)(1) mg(-)(1) (V(max)) and 28.88 microM (K(M)). Our data indicate that Muller cells in the chicken retina possess 11-cis-ARAT activity, thus providing an explanation for the accumulation of 11-cis-retinyl esters in the cone cycle.
[Mh] Termos MeSH primário: Retinol O-Graxo-Aciltransferase/metabolismo
[Mh] Termos MeSH secundário: Animais
Células Cultivadas
Galinhas
Isomerismo
Cinética
Palmitoil Coenzima A/metabolismo
Progesterona/farmacologia
Retina/citologia
Retina/enzimologia
Retinol O-Graxo-Aciltransferase/antagonistas & inibidores
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL
[Nm] Nome de substância:
1763-10-6 (Palmitoyl Coenzyme A); 4G7DS2Q64Y (Progesterone); EC 2.3.1.76 (Retinol O-Fatty-Acyltransferase)
[Em] Mês de entrada:0611
[Cu] Atualização por classe:161122
[Lr] Data última revisão:
161122
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:061004
[St] Status:MEDLINE


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Fotocópia
[PMID]:16054134
[Au] Autor:Kaschula CH; Jin MH; Desmond-Smith NS; Travis GH
[Ad] Endereço:Jules Stein Eye Institute, UCLA School of Medicine, Los Angeles, CA 90095, USA.
[Ti] Título:Acyl CoA:retinol acyltransferase (ARAT) activity is present in bovine retinal pigment epithelium.
[So] Source:Exp Eye Res;82(1):111-21, 2006 Jan.
[Is] ISSN:0014-4835
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:Visual perception is mediated by a family of G protein-coupled receptors called the opsins. The light-absorbing chromophore in most opsins is 11-cis-retinaldehyde, which is isomerized to all-trans-retinaldehyde upon absorption of a photon. Restoration of light sensitivity to the photobleached opsin requires chemical re-isomerization of the chromophore. This is carried out by an enzymatic pathway called the visual cycle in retinal pigment epithelial cells. The isomerase in this pathway uses fatty-acyl esters of all-trans-retinol as substrate. A retinyl-ester synthase that produces these esters, called lecithin:retinol acyltransferase (LRAT), has been extensively characterized. Based on prior biochemical studies and the phenotype in lrat(-/-) knockout mice, it has been assumed that LRAT is the sole or dominant retinyl-ester synthase in the retinal pigment epithelium. Here we demonstrate the presence of a second ester synthase activity in these cells called acyl CoA:retinol acyltransferase (ARAT). We show that this activity uses palmitoyl coenzyme A as an acyl donor, unlike LRAT which uses phosphatidylcholine. Similar to LRAT, ARAT esterifies both all-trans-retinol and 11-cis-retinol. LRAT and ARAT are both potently inhibited by the retinyl-ester analog, all-trans-retinylbromoacetate, but only ARAT is inhibited by progesterone. Unexpectedly, the maximum turnover rate (V(max)) of ARAT was similar to that of LRAT. However, the Michaelis constant (K(M)) of ARAT was 10-fold higher than the K(M) of LRAT for all-trans-retinol. These observations suggest that ARAT may complement LRAT to provide additional retinyl-ester synthase activity under conditions of high all-trans-retinol. These conditions occur in the retina following exposure to bright light.
[Mh] Termos MeSH primário: Epitélio Pigmentado Ocular/enzimologia
Retinol O-Graxo-Aciltransferase/análise
[Mh] Termos MeSH secundário: Aciltransferases/metabolismo
Animais
Bovinos
Linhagem Celular
Membrana Celular/química
Clonagem Molecular
Seres Humanos
Immunoblotting
Camundongos
Microssomos/química
Palmitoil Coenzima A/farmacologia
Retinol O-Graxo-Aciltransferase/genética
Estimulação Química
Transfecção/métodos
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
1763-10-6 (Palmitoyl Coenzyme A); EC 2.3.- (Acyltransferases); EC 2.3.1.- (lecithin-retinol acyltransferase); EC 2.3.1.76 (Retinol O-Fatty-Acyltransferase)
[Em] Mês de entrada:0604
[Cu] Atualização por classe:061115
[Lr] Data última revisão:
061115
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:050802
[St] Status:MEDLINE



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