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1.
JID Innov ; 3(2): 100165, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36699197

RESUMO

To enhance the understanding of molecular mechanisms and mine previously unidentified biomarkers of pediatric atopic dermatitis, PBMC gene expression profiles were generated by RNA sequencing in infants with atopic dermatitis and age-matched controls. A total of 178 significantly differentially expressed genes (DEGs) (115 upregulations and 63 downregulations) were seen, compared with those in healthy controls. The DEGs identified included IL1ß, TNF, TREM1, IL18R1, and IL18RAP. DEGs were validated by real-time RT- qPCR in a larger number of samples from PBMCs of infants with atopic dermatitis aged <12 months. Using the DAVID (Database for Annotation, Visualization and Integrated Discovery) database, functional and pathway enrichment analyses of DEGs were performed. Gene ontology enrichment analysis showed that DEGs were associated with immune responses, inflammatory responses, regulation of immune responses, and platelet activation. Pathway analysis indicated that DEGs were enriched in cytokine‒cytokine receptor interaction, immunoregulatory interactions between lymphoid and nonlymphoid cells, hematopoietic cell lineage, phosphoinositide 3-kinase‒protein kinase B signaling pathway, NK cell‒mediated cytotoxicity, and platelet activation. Furthermore, the protein‒protein interaction network was predicted using the STRING (Search Tool for the Retrieval of Interacting Genes/Proteins) database and visualized with Cytoscape software. Finally, on the basis of the protein‒protein interaction network, 18 hub genes were selected, and two significant modules were obtained. In conclusion, this study sheds light on the molecular mechanisms of pediatric atopic dermatitis and may provide diagnostic biomarkers and therapeutic targets.

2.
Exp Dermatol ; 31(4): 567-576, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-34787924

RESUMO

BACKGROUND: Psoriasis is characterized by aberrant activation of several pro-inflammatory circuits as well as abnormal hyperproliferation and dysregulated apoptosis of keratinocytes (KCs). Most currently available therapeutic options primarily target psoriasis-associated immunological defects rather than epidermal abnormalities. OBJECTIVE: To investigate the efficacy of the histone deacetylase (HDAC) inhibitor, Vorinostat, in targeting hyperproliferation and impaired apoptosis in psoriatic skin. METHODS: Vorinostat effect was investigated in primary KCs cell cultures using cell cycle analysis by flow cytometry, apoptosis assays (Annexin V-FICH and caspase-3/7) and antibody arrays, qRT-PCR and immunohistochemistry. Vorinostat impact on clinical manifestations of psoriasis was investigated in a chimeric mouse model. RESULTS: Vorinostat was found to inhibit KCs proliferation and to induce their differentiation and apoptosis. Using a chimeric mouse model, vorinostat was found to result in marked attenuation of a psoriasiform phenotype with a significant decrease in epidermal thickness and inhibition of epidermal proliferation. CONCLUSIONS: Our results support the notion that vorinostat, a prototypic HDAC inhibitor, may be of potential use in the treatment of psoriasis and other hyperproliferative skin disorders.


Assuntos
Inibidores de Histona Desacetilases , Psoríase , Animais , Apoptose , Linhagem Celular Tumoral , Proliferação de Células , Inibidores de Histona Desacetilases/farmacologia , Inibidores de Histona Desacetilases/uso terapêutico , Camundongos , Psoríase/tratamento farmacológico , Vorinostat/farmacologia , Vorinostat/uso terapêutico
3.
J Invest Dermatol ; 136(12): 2340-2341, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27884290

RESUMO

In complex disease such as atopic dermatitis, the journey from identification of strong risk loci to profound functional and mechanistic insights can take several years. Here, Manz et al. have elegantly deciphered the mechanistic pathways in the well-established 11q13.5 atopic dermatitis risk locus. Their genetic and functional insights emphasize a role for T regulatory cells in atopic dermatitis pathogenesis.


Assuntos
Dermatite Atópica/genética , Dermatite Atópica/fisiopatologia , Predisposição Genética para Doença/epidemiologia , Proteínas de Membrana/genética , Progressão da Doença , Feminino , Regulação da Expressão Gênica , Variação Genética , Humanos , Masculino , Prognóstico , Índice de Gravidade de Doença
4.
Exp Dermatol ; 24(8): 618-22, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25939713

RESUMO

Alopecia-neurological defects-endocrinopathy (ANE) syndrome is a rare inherited hair disorder, which was shown to result from decreased expression of the RNA-binding motif protein 28 (RBM28). In this study, we attempted to delineate the role of RBM28 in hair biology. First, we sought to obtain evidence for the direct involvement of RBM28 in hair growth. When RBM28 was downregulated in human hair follicle (HF) organ cultures, we observed catagen induction and HF growth arrest, indicating that RBM28 is necessary for normal hair growth. We also aimed at identifying molecular targets of RBM28. Given that an RBM28 homologue was recently found to regulate miRNA biogenesis in C. elegans and given the known pivotal importance of miRNAs for proper hair follicle development, we studied global miRNA expression profile in cells knocked down for RBM28. This analysis revealed that RBM28 controls the expression of miR-203. miR-203 was found to regulate in turn TP63, encoding the transcription factor p63, which is critical for hair morphogenesis. In conclusion, RBM28 contributes to HF growth regulation through modulation of miR-203 and p63 activity.


Assuntos
Alopecia/metabolismo , Doenças do Sistema Endócrino/metabolismo , Regulação da Expressão Gênica , Folículo Piloso/metabolismo , Deficiência Intelectual/metabolismo , MicroRNAs/fisiologia , Proteínas de Ligação a RNA/fisiologia , Fatores de Transcrição/fisiologia , Proteínas Supressoras de Tumor/fisiologia , Alopecia/fisiopatologia , Células Cultivadas , Doenças do Sistema Endócrino/fisiopatologia , Genes Reporter , Cabelo/crescimento & desenvolvimento , Folículo Piloso/crescimento & desenvolvimento , Humanos , Deficiência Intelectual/fisiopatologia , Queratinócitos/metabolismo , Morfogênese , Técnicas de Cultura de Órgãos , Interferência de RNA , RNA Interferente Pequeno/genética , Proteínas de Ligação a RNA/genética , Transfecção , Regulação para Cima
6.
Am J Med Genet A ; 161A(9): 2204-15, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23918762

RESUMO

3-Methylglutaconic aciduria (3-MGCA) type IV is defined as a heterogeneous group of inborn errors featuring in common 3-MGCA and associated with primary mitochondrial dysfunction leading to a spectrum of multisystem conditions. We studied four patients who presented at birth with a clinical picture simulating a primary mitochondrial hepatic disorder consistent with the MEGDEL syndrome including 3-MGCA, sensorineural deafness, encephalopathy and a brain magnetic resonance imaging with signs of Leigh disease. All affected children displayed biochemical features consistent with mitochondrial OXPHOS dysfunction including hepatic mitochondrial DNA depletion in one patient. Homozygosity mapping identified a candidate locus on 6q25.2-6q26. Using whole exome sequencing, we identified two novel homozygous mutations in SERAC1 recently reported to harbor mutations in MEGDEL syndrome. Both mutations were found to lead to decreased or absent expression of SERAC1. The present findings indicate that infantile hepatopathy is a cardinal feature of MEGDEL syndrome. We thus propose to rename the disease MEGDHEL syndrome.


Assuntos
Anormalidades Múltiplas/genética , Hidrolases de Éster Carboxílico/genética , Perda Auditiva Neurossensorial/genética , Doença de Leigh/genética , Hepatopatias/genética , Erros Inatos do Metabolismo/genética , Doenças Mitocondriais/genética , Mutação , Anormalidades Múltiplas/diagnóstico , Encéfalo/patologia , Estudos de Casos e Controles , Mapeamento Cromossômico , Consanguinidade , Análise Mutacional de DNA , Complexo de Proteínas da Cadeia de Transporte de Elétrons/metabolismo , Perda Auditiva Neurossensorial/diagnóstico , Homozigoto , Humanos , Recém-Nascido , Doença de Leigh/diagnóstico , Fígado/patologia , Fígado/ultraestrutura , Hepatopatias/diagnóstico , Imageamento por Ressonância Magnética , Masculino , Erros Inatos do Metabolismo/diagnóstico , Repetições de Microssatélites/genética , Mitocôndrias/patologia , Mitocôndrias/ultraestrutura , Doenças Mitocondriais/diagnóstico , Linhagem , Polimorfismo de Nucleotídeo Único , Síndrome
8.
Exp Dermatol ; 22(4): 251-4, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23528209

RESUMO

Autosomal recessive congenital ichthyosis refers to a heterogeneous group of cornification disorders of major impact on patients' life. The disease has been linked so far to mutations in 8 distinct genes. We report a consanguineous family of Arab Muslim origin with several members displaying a severe form of congenital ichthyosiform erythroderma. Using a panel of polymorphic microsatellite markers, we identified a region of homozygosity shared by all patients on 2q34, in a region harbouring the ABCA12 gene. Direct sequencing of genomic DNA derived from a patient failed to reveal any obviously pathogenic change in the coding sequence of this gene. In contrast, cDNA sequence analysis revealed the existence of a 163-bp-long deletion in exon 24, thus pointing to a splicing defect. Careful reanalysis of the genomic DNA sequence revealed apart from several known single-nucleotide polymorphisms, a hitherto unreported homozygous synonymous mutation in exon 24 (c.3456G>A; p.S1152S), which was found to lead to the formation of a novel splicing acceptor site. Synonymous mutations have been shown to uncommonly cause inherited disorders in humans. Here, we present the first example of a congenital form of ichthyosis resulting from such a genetic defect.


Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Eritrodermia Ictiosiforme Congênita/genética , Mutação , Adolescente , Árabes/genética , Cromossomos Humanos Par 2/genética , Consanguinidade , Análise Mutacional de DNA , Feminino , Genes Recessivos , Homozigoto , Humanos , Israel , Masculino , Linhagem
9.
Am J Hum Genet ; 91(2): 337-42, 2012 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-22840363

RESUMO

Disproportionate short stature refers to a heterogeneous group of hereditary disorders that are classified according to their mode of inheritance, clinical skeletal and nonskeletal manifestations, and radiological characteristics. In the present study, we report on an autosomal-recessive osteocutaneous disorder that we termed SOFT (short stature, onychodysplasia, facial dysmorphism, and hypotrichosis) syndrome. We employed homozygosity mapping to locate the disease-causing mutation to region 3p21.1-3p21.31. Using whole-exome-sequencing analysis complemented with Sanger direct sequencing of poorly covered regions, we identified a homozygous point mutation (c.512T>C [p.Leu171Pro]) in POC1A (centriolar protein homolog A). This mutation was found to cosegregate with the disease phenotype in two families. The p.Leu171Pro substitution affects a highly conserved amino acid residue and is predicted to interfere with protein function. Poc1, a POC1A ortholog, was previously found to have a role in centrosome stability in unicellular organisms. Accordingly, although centrosome structure was preserved, the number of centrosomes and their distribution were abnormal in affected cells. In addition, the Golgi apparatus presented a dispersed morphology, cholera-toxin trafficking from the plasma membrane to the Golgi was aberrant, and large vesicles accumulated in the cytosol. Collectively, our data underscore the importance of POC1A for proper bone, hair, and nail formation and highlight the importance of normal centrosomes in Golgi assembly and trafficking from the plasma membrane to the Golgi apparatus.


Assuntos
Anormalidades Múltiplas/genética , Cromossomos Humanos Par 3/genética , Hipotricose/genética , Proteínas/genética , Anormalidades Múltiplas/patologia , Sequência de Aminoácidos , Sequência de Bases , Proteínas de Ciclo Celular , Mapeamento Cromossômico , Proteínas do Citoesqueleto , Exoma/genética , Feminino , Complexo de Golgi/patologia , Humanos , Indóis , Masculino , Microscopia Confocal , Dados de Sequência Molecular , Linhagem , Mutação Puntual/genética , Polimorfismo de Fragmento de Restrição/genética , Transporte Proteico/genética , Análise de Sequência de DNA
10.
Am J Hum Genet ; 91(1): 163-70, 2012 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-22703878

RESUMO

Pityriasis rubra pilaris (PRP) is a papulosquamous disorder phenotypically related to psoriasis. The disease has been occasionally shown to be inherited in an autosomal-dominant fashion. To identify the genetic cause of familial PRP, we ascertained four unrelated families affected by autosomal-dominant PRP. We initially mapped PRP to 17q25.3, a region overlapping with psoriasis susceptibility locus 2 (PSORS2 [MIM 602723]). Using a combination of linkage analysis followed by targeted whole-exome sequencing and candidate-gene screening, we identified three different heterozygous mutations in CARD14, which encodes caspase recruitment domain family, member 14. CARD14 was found to be specifically expressed in the skin. CARD14 is a known activator of nuclear factor kappa B signaling, which has been implicated in inflammatory disorders. Accordingly, CARD14 levels were increased, and p65 was found to be activated in the skin of PRP-affected individuals. The present data demonstrate that autosomal-dominant PRP is allelic to familial psoriasis, which was recently shown to also be caused by mutations in CARD14.


Assuntos
Proteínas Adaptadoras de Sinalização CARD/genética , Guanilato Ciclase/genética , Proteínas de Membrana/genética , Mutação , Pitiríase Rubra Pilar/genética , Adulto , Sequência de Bases , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Linhagem , Pele/metabolismo
11.
Am J Hum Genet ; 89(2): 302-7, 2011 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-21820097

RESUMO

Monogenic disorders offer unique opportunities for researchers to shed light upon fundamental physiological processes in humans. We investigated a large family affected with autosomal-dominant adermatoglyphia (absence of fingerprints) also known as the "immigration delay disease." Using linkage and haplotype analyses, we mapped the disease phenotype to 4q22. One of the genes located in this interval is SMARCAD1, a member of the SNF subfamily of the helicase protein superfamily. We demonstrated the existence of a short isoform of SMARCAD1 exclusively expressed in the skin. Sequencing of all SMARCAD1 coding and noncoding exons revealed a heterozygous transversion predicted to disrupt a conserved donor splice site adjacent to the 3' end of a noncoding exon uniquely present in the skin-specific short isoform of the gene. This mutation segregated with the disease phenotype throughout the entire family. Using a minigene system, we found that this mutation causes aberrant splicing, resulting in decreased stability of the short RNA isoform as predicted by computational analysis and shown by RT-PCR. Taken together, the present findings implicate a skin-specific isoform of SMARCAD1 in the regulation of dermatoglyph development.


Assuntos
Genes Dominantes/genética , Mutação/genética , Dermatopatias/genética , Pele/patologia , Sequência de Bases , Mapeamento Cromossômico , DNA Helicases/genética , DNA Helicases/metabolismo , Análise Mutacional de DNA , Feminino , Perfilação da Expressão Gênica , Haplótipos/genética , Células HeLa , Humanos , Escore Lod , Masculino , Dados de Sequência Molecular , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Conformação de Ácido Nucleico , Especificidade de Órgãos/genética , Linhagem , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Pele/metabolismo
13.
Am J Hum Genet ; 88(4): 482-7, 2011 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-21439540

RESUMO

Autosomal-recessive congenital ichthyoses represent a large and heterogeneous group of disorders of epidermal cornification. Recent data suggest that most of these disorders might result from defective lipid transport and metabolism. In the present study, we describe a late-onset form of recessive ichthyosis in a large consanguineous pedigree. By using a combination of homozygosity mapping and positional candidate-gene screening, we identified a 2 bp deletion in LIPN that segregated with the disease phenotype throughout the family. LIPN encodes one of six acid lipases known to be involved in triglyceride metabolism in mammals . LIPN was found to be exclusively expressed in the epidermis and to be strongly induced during keratinocyte differentiation.


Assuntos
Ictiose/enzimologia , Ictiose/genética , Lipase/genética , Deleção de Sequência , Adolescente , Sequência de Bases , Consanguinidade , Primers do DNA/genética , Feminino , Genes Recessivos , Haplótipos , Homozigoto , Humanos , Ictiose/patologia , Masculino , Linhagem , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição
14.
J Invest Dermatol ; 130(2): 378-87, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19710688

RESUMO

Insulin-like growth factor (IGF)-binding protein 7 (IGFBP7) belongs to the IGFBP superfamily, which is involved in the regulation of IGF and insulin signaling. Recently, a global gene expression study revealed that IGFBP7 is downregulated in the psoriatic epidermis, with UVB phototherapy restoring its expression to normal. In the present study, we confirmed that IGFBP7 expression is decreased in psoriatic lesions. Given the previous data suggesting a role for IGFBP7 in the control of cancer cell growth, we investigated its involvement in the regulation of keratinocyte (KC) proliferation and differentiation, which are abnormal in psoriasis. To model IGFBP7 downregulation in vitro, we used IGFBP7-specific small interfering RNA or small hairpin RNA-expressing lentiviral vectors in HaCaT cells or primary human KCs. Downregulation of IGFBP7 was found to markedly enhance KC proliferation in both systems, was associated with a significant decrease in KC susceptibility to tumor necrosis factor-alpha-induced apoptosis, but did not affect senescence. Downregulation of IGFBP7 was also shown to block expression of genes associated with calcium-induced differentiation of human KCs. Finally, recombinant IGFBP7 was found to inhibit KC proliferation and enhanced their apoptosis. These data position IGFBP7 as a regulator of KC proliferation and differentiation, suggesting a potential role for this protein in the pathophysiology and treatment of hyperproliferative dermatoses such as psoriasis.


Assuntos
Apoptose , Regulação da Expressão Gênica , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina/metabolismo , Queratinócitos/metabolismo , Diferenciação Celular , Linhagem Celular , Linhagem Celular Tumoral , Proliferação de Células , Senescência Celular , Regulação para Baixo , Humanos , Queratinócitos/citologia , Receptor de Insulina/metabolismo , Proteínas Recombinantes/química , Transdução de Sinais , Fator de Necrose Tumoral alfa/metabolismo
15.
Am J Hum Genet ; 82(5): 1114-21, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18439547

RESUMO

Single-gene disorders offer unique opportunities to shed light upon fundamental physiological processes in humans. We investigated an autosomal-recessive phenotype characterized by alopecia, progressive neurological defects, and endocrinopathy (ANE syndrome). By using homozygosity mapping and candidate-gene analysis, we identified a loss-of-function mutation in RBM28, encoding a nucleolar protein. RBM28 yeast ortholog, Nop4p, was previously found to regulate ribosome biogenesis. Accordingly, electron microscopy revealed marked ribosome depletion and structural abnormalities of the rough endoplasmic reticulum in patient cells, ascribing ANE syndrome to the restricted group of inherited disorders associated with ribosomal dysfunction.


Assuntos
Alopecia/genética , Doenças do Sistema Endócrino/genética , Predisposição Genética para Doença , Doenças do Sistema Nervoso/genética , Proteínas Nucleares/genética , Proteínas de Ligação a RNA/genética , Adulto , Alopecia/metabolismo , Alopecia/patologia , Sequência de Aminoácidos , Nucléolo Celular/metabolismo , Células Cultivadas , Doenças do Sistema Endócrino/metabolismo , Doenças do Sistema Endócrino/patologia , Retículo Endoplasmático/metabolismo , Retículo Endoplasmático/ultraestrutura , Feminino , Humanos , Masculino , Dados de Sequência Molecular , Doenças do Sistema Nervoso/metabolismo , Doenças do Sistema Nervoso/patologia , Proteínas Nucleares/metabolismo , Linhagem , Polimorfismo de Nucleotídeo Único , Proteínas de Ligação a RNA/metabolismo , Ribossomos/metabolismo , Ribossomos/ultraestrutura , Síndrome
16.
J Biol Chem ; 283(5): 2724-33, 2008 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-18045875

RESUMO

Macrophages are a central arm of innate immune defense against intracellular pathogens. They internalize microbes into phagosomes where the invaders are being killed by oxygen and nitrogen reactive species. Despite this battery of antimicrobial molecules, some are able to thrive within the phagosome thus termed intraphagosomal pathogens among which are Salmonella, Leishmania, and Mycobacteria. In mice, a single dominant gene termed Nramp1/Slc11a1 controls innate resistance to such pathogens. This gene is expressed exclusively in myeloid cells. Previously, we have shown that the restricted expression of Nramp1 is regulated by a myeloid cell-specific transcription factor termed IRF-8/ICSBP. It is demonstrated here that the induction of Nramp1 expression in activated macrophages is accompanied by a promoter shift from a repression state elicited by c-Myc to an activation state elicited by the induction of IRF-8 in activated macrophages. This transition from repression to activation is facilitated by a competitive protein-protein interaction with the transcription factor Miz-1. To show that IRF-8 is directly involved in the elimination of intraphagosomal pathogens through the regulation of Nramp1 gene expression, we bred wild type as well as IRF-8 and Nramp1 null mouse strains and examined macrophages derived from bone marrow and peritoneum. Our results clearly show that the absence of IRF-8 and Nramp1 leads to the same phenotype; defective killing of intraphagosomal Salmonella enterica serovar typhimurium and Mycobacterium bovis. Thus, interplay between repression and activation state of the Nramp1 promoter mediated by IRF-8 provides the molecular basis by which macrophages resist intraphagosomal pathogens at early stage after infection.


Assuntos
Proteínas de Transporte de Cátions/genética , Proteínas de Transporte de Cátions/imunologia , Imunidade Inata , Fatores Reguladores de Interferon/imunologia , Macrófagos/imunologia , Macrófagos/microbiologia , Fagossomos/imunologia , Fagossomos/microbiologia , Proteínas Proto-Oncogênicas c-myc/imunologia , Animais , Sequência de Bases , Sítios de Ligação/genética , Linhagem Celular , DNA/genética , DNA/metabolismo , Primers do DNA/genética , Fatores Reguladores de Interferon/deficiência , Fatores Reguladores de Interferon/genética , Ativação de Macrófagos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mycobacterium bovis/imunologia , Regiões Promotoras Genéticas , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Salmonella typhimurium/imunologia , Transativadores/genética , Transativadores/metabolismo
17.
Biochem Pharmacol ; 70(11): 1548-59, 2005 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-16226723

RESUMO

Microsomal triglyceride transfer protein (MTP) catalyzes the assembly and secretion of liver triglyceride-rich lipoproteins. The human MTP (hMTP) promoter activity is reported here to be suppressed by HNF-4alpha ligand antagonists (e.g., Medica analogs) or by PPARgamma ligand agonists (e.g., thiazolidinediones), thus accounting for their hypolipidemic activity in humans. Suppression of liver hMTP by Medica analogs or by thiazolidinediones was mediated by the TAAA sequence that serves as non-canonical TATA box of the hMTP core promoter. MTP suppression was evident in the specific context of the wild type hMTP core promoter, but not in the context of the mutated rodent-conforming hMTP core promoter governed by a canonical TATA box conjoined with its proximal (-50/-38)DR-1 element. hMTP suppression by Medica analogs or thiazolidinediones mediated by hMTP TAAA was independent of HNF-4alpha or PPARgamma. hMTP suppression by Medica analogs, but not by thiazolidinediones, was further complemented by inhibition of HNF-4alpha transcriptional activity transduced by the distal (-83/-70)DR-1 element of hMTP promoter. hMTP promoter activity was unaffected by PPARalpha activation. Furthermore, in contrast to hMTP, the promoter activity of the rodent-conforming hMTP was robustly activated by Wy-14,643-activated PPARalpha or by thiazolidinedione-activated PPARgamma. Transcriptional activation by PPARalpha or PPARgamma of the rodent-conforming, but not the wild type hMTP gene promoter, resulted from the species-specific context of the respective proximal DR-1 elements. Hence, suppression of hMTP transcription by hypolipidemic insulin sensitizers requires the specific context of hMTP core promoter. In light of the species-specific context of MTP core promoters, the rodent MTP promoter may not substitute for the human promoter when searching for hypolipidemic MTP suppressors.


Assuntos
Proteínas de Transporte/genética , Hipolipemiantes/farmacologia , Transcrição Gênica/efeitos dos fármacos , Animais , Linhagem Celular , Fator 4 Nuclear de Hepatócito/metabolismo , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Humanos , Insulina/metabolismo , Ligantes , Camundongos , Receptores Ativados por Proliferador de Peroxissomo/metabolismo , Regiões Promotoras Genéticas/genética , Ratos
18.
Biochem J ; 388(Pt 1): 325-32, 2005 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-15651981

RESUMO

HNF-4alpha (hepatocyte nuclear factor-4alpha) is required for tissue-specific expression of many of the hepatic, pancreatic, enteric and renal traits. Heterozygous HNF-4alpha mutants are inflicted by MODY-1 (maturity onset diabetes of the young type-1). HNF-4alpha expression is reported here to be negatively autoregulated by HNF-4alpha1 and to be activated by dominant-negative HNF-4alpha1. Deletion and chromatin immunoprecipitation analysis indicated that negative autoregulation by HNF-4alpha1 was mediated by its association with the TATA-less HNF-4alpha core promoter enriched in Sp1, but lacking DR-1 response elements. Also, negative autoregulation by HNF-4alpha1 was independent of its transactivation function, being similarly exerted by transcriptional-defective MODY-1 missense mutants of HNF-4alpha1, or under conditions of suppressing or enhancing HNF-4alpha activity by small heterodimer partner or by inhibiting histone deacetylase respectively. Negative autoregulation by HNF-4alpha1 was abrogated by overexpressed Sp1. Transcriptional suppression by HNF-4alpha1 independently of its transactivation function may extend the scope of its transcriptional activity to interference with docking of the pre-transcriptional initiation complex to TATA-less promoters.


Assuntos
Regulação da Expressão Gênica , Fator 4 Nuclear de Hepatócito/genética , Linhagem Celular , Humanos , Regiões Promotoras Genéticas , Ativação Transcricional
19.
J Lipid Res ; 46(2): 328-41, 2005 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-15547294

RESUMO

Microsomal triglyceride transfer protein (MTP) catalyzes the assembly of triglyceride (TG)-rich apolipoprotein B-containing liver (e.g., VLDL) and intestinal (e.g., chylomicron) lipoproteins. The human MTP gene promoter is reported here to associate in vivo with endogenous hepatocyte nuclear factor-4alpha (HNF-4alpha) and to be transactivated or transsuppressed by overexpressed or by dominant negative HNF-4alpha, respectively. Human MTP (hMTP) transactivation by HNF-4alpha is accounted for by the concerted activity of distal (-83/-70) and proximal (-50/-38) direct repeat 1 elements of the hMTP promoter that bind HNF-4alpha. Transactivation by HNF-4alpha is specifically antagonized by chicken ovalbumin upstream promoter. Transcriptional activation of hMTP by HNF-4alpha is mediated by HNF-4alpha domains engaged in ligand binding and ligand-driven transactivation and is further complemented by HNF-4alpha/HNF-1alpha synergism that involves the HNF-4alpha activation function 1 (AF-1) domain. hMTP transactivation by HNF-4alpha is specifically inhibited by beta,beta-tetramethyl-hexadecanedioic acid acting as an HNF-4alpha antagonist ligand. hMTP transactivation by HNF-4alpha may account for the activation or inhibition of MTP expression and the production of TG-rich lipoproteins by agonist (e.g., saturated fatty acids) or antagonist [e.g., (n-3) PUFA, hypolipidemic fibrates, or Methyl-substituted dicarboxylic acid (Medica) compounds] HNF-4alpha ligands.


Assuntos
Proteínas de Transporte/biossíntese , Proteínas de Transporte/genética , Proteínas de Ligação a DNA/fisiologia , Regulação da Expressão Gênica , Fosfoproteínas/fisiologia , Fatores de Transcrição/fisiologia , Transcrição Gênica , Animais , Catálise , Linhagem Celular , Núcleo Celular/metabolismo , Galinhas , Imunoprecipitação da Cromatina , Proteínas de Ligação a DNA/metabolismo , Ácidos Graxos/metabolismo , Células HeLa , Fator 4 Nuclear de Hepatócito , Hepatócitos/metabolismo , Humanos , Ligantes , Lipoproteínas VLDL/metabolismo , Modelos Genéticos , Mutação , Ovalbumina/genética , Fosfoproteínas/metabolismo , Plasmídeos/metabolismo , Regiões Promotoras Genéticas , RNA Mensageiro/metabolismo , Elementos de Resposta , Fatores de Tempo , Fatores de Transcrição/metabolismo , Ativação Transcricional , Transfecção
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