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1.
Adv Sci (Weinh) ; 11(24): e2308021, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38561969

RESUMO

The severe Zn-dendrite growth and insufficient carbon-based cathode performance are two critical issues that hinder the practical applications of flexible Zn-ion micro-ssupercapacitors (FZCs). Herein, a self-adaptive electrode design concept of the synchronous improvement on both the cathode and anode is proposed to enhance the overall performance of FZCs. Polypyrrole doped with anti-expansion graphene oxide and acrylamide (PPy/GO-AM) on the cathode side can exhibit remarkable electrochemical performance, including decent capacitance and cycling stability, as well as exceptional mechanical properties. Meanwhile, a robust protective polymeric layer containing reduced graphene oxide and polyacrylamide is self-assembled onto the Zn surface (rGO/PAM@Zn) at the anode side, by which the "tip effect" of Zn small protuberance can be effectively alleviated, the Zn-ion distribution homogenized, and dendrite growth restricted. Benefiting from these advantages, the FZCs deliver an excellent specific capacitance of 125 mF cm-2 (125 F cm-3) at 1 mA cm-2, along with a maximum energy density of 44.4 µWh cm-2, and outstanding long-term durability with 90.3% capacitance remained after 5000 cycles. This conformal electrode design strategy is believed to enlighten the practical design of high-performance in-plane flexible Zn-based electrochemical energy storage devices (EESDs) by simultaneously tackling the challenges faced by Zn anodes and capacitance-type cathodes.

2.
J Am Chem Soc ; 146(9): 6397-6407, 2024 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-38394777

RESUMO

Catalyst supports play an essential role in catalytic reactions, hinting at pronounced metal-support effects. Zeolites are a propitious support in heterogeneous catalysts, while their use in the electrocatalytic CO2 reduction reaction has been limited as yet because of their electrically insulating nature and serious competing hydrogen evolution reaction (HER). Enlightened by theoretical prediction, herein, we implant zinc ions into the structural skeleton of a zeolite Y to strategically tailor a favorable electrocatalytic platform with remarkably enhanced electronic conduction and strong HER inhibition capability, which incorporates ultrafine cadmium oxide nanoclusters as guest species into the supercages of the tailored 12-ring window framework. The metal d-bandwidth tuning of cadmium by skeletal zinc steers the extent of substrate-molecule orbital mixing, enhancing the stabilization of the key intermediate *COOH while weakening the CO poisoning effect. Furthermore, the strong cadmium-zinc interplay causes a considerable thermodynamic barrier for water dissociation in the conversion of H+ to *H, potently suppressing the competing HER. Therefore, we achieve an industrial-level partial current density of 335 mA cm-2 and remarkable Faradaic efficiency of 97.1% for CO production and stably maintain Faradaic efficiency above 90% at the industrially relevant current density for over 120 h. This work provides a proof of concept of tailored conductive zeolite as a favorable electrocatalytic support for industrial-level CO2 electrolysis and will significantly enhance the adaptability of conductive zeolite-based electrocatalysts in a variety of electrocatalysis and energy conversion applications.

3.
Mol Cell Endocrinol ; 549: 111641, 2022 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-35398053

RESUMO

Luteinizing hormone (LH) stimulates testosterone production from Leydig cells. Both LH and testosterone play important roles in spermatogenesis and male fertility. To identify LH - and testosterone - responsive transporter genes that play key roles in spermatogenesis, we performed large-scale gene expression analyses on testes obtained from adult control and Lhb knockout mice. We found a significant reduction in cystine/glutamate transporter encoding Slc7a11 mRNA in testes of Lhb null mice. We observed that Slc7a11/SLC7A11 expression was initiated pre-pubertally and developmentally regulated in mouse testis. Immunolocalization studies confirmed that SLC7A11 was mostly expressed in Sertoli cells in testes of control and germ cell-deficient mice. Western blot analyses indicated that SLC7A11 was significantly reduced in testes of mutant mice lacking either LH or androgen receptor selectively in Sertoli cells. Genetic and pharmacological rescue of Lhb knockout mice restored the testicular expression of Slc7a11 comparable to that observed in controls. Additionally, Slc7a11 mRNA was significantly suppressed upon Sertoli cell/testicular damage induced in mice by cadmium treatment. Knockdown of Slc7a11 in vitro in TM4 Sertoli cells or treatment of mice with sulfasalazine, a SLC7A11 inhibitor caused a significant reduction in intracellular cysteine and glutathione levels but glutamate content remained unchanged as determined by metabolomic analysis. Knockdown of Slc7a11 resulted in compensatory upregulation of other glutamate transporters belonging to the Slc1a family presumably to maintain intracellular glutamate levels. Collectively, our studies identified that SLC7A11 is an LH/testosterone-regulated transporter that is required for cysteine/glutathione but not glutamate homeostasis in mouse Sertoli cells.


Assuntos
Sistema y+ de Transporte de Aminoácidos/metabolismo , Androgênios , Células de Sertoli , Androgênios/metabolismo , Animais , Cisteína/metabolismo , Cistina/metabolismo , Glutamatos/metabolismo , Glutationa/metabolismo , Homeostase , Células Intersticiais do Testículo/metabolismo , Hormônio Luteinizante/farmacologia , Masculino , Camundongos , Camundongos Knockout , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Células de Sertoli/metabolismo , Espermatogênese , Testículo/metabolismo , Testosterona/farmacologia
4.
Dev Cell ; 57(7): 914-929.e7, 2022 04 11.
Artigo em Inglês | MEDLINE | ID: mdl-35320732

RESUMO

Fallopian tube (FT) homeostasis requires dynamic regulation of heterogeneous cell populations and is disrupted in infertility and ovarian cancer. Here, we applied single-cell RNA-seq to profile 59,738 FT cells from four healthy, pre-menopausal subjects. The resulting cell atlas contains 12 major cell types representing epithelial, stromal, and immune compartments. Re-clustering of epithelial cells identified four ciliated and six non-ciliated secretory epithelial subtypes, two of which represent potential progenitor pools: one leading to mature secretory cells and the other contributing to either ciliated cells or one of the stromal cell types. To understand how FT cell numbers and states change in a disease state, we analyzed 17,798 cells from two hydrosalpinx samples and observed shifts in epithelial and stromal populations and cell-type-specific changes in extracellular matrix and TGF-ß signaling; this underscores fibrosis pathophysiology. This resource is expected to facilitate future studies aimed at expanding understanding of fallopian tube homeostasis in normal development and disease.


Assuntos
Tubas Uterinas , Neoplasias Ovarianas , Células Epiteliais/metabolismo , Tubas Uterinas/metabolismo , Feminino , Humanos , Neoplasias Ovarianas/metabolismo , Análise de Célula Única
5.
Genes (Basel) ; 12(8)2021 07 25.
Artigo em Inglês | MEDLINE | ID: mdl-34440302

RESUMO

We report four allelic variants (three novel) in three genes previously established as causal for hypopituitarism or related disorders. A novel homozygous variant in the growth hormone gene, GH1 c.171delT (p.Phe 57Leufs*43), was found in a male patient with severe isolated growth hormone deficiency (IGHD) born to consanguineous parents. A hemizygous SOX3 allelic variant (p.Met304Ile) was found in a male patient with IGHD and hypoplastic anterior pituitary. YASARA, a tool to evaluate protein stability, suggests that p.Met304Ile destabilizes the SOX3 protein (ΔΔG = 2.49 kcal/mol). A rare, heterozygous missense variant in the TALE homeobox protein gene, TGIF1 (c.268C>T:p.Arg90Cys) was found in a patient with combined pituitary hormone deficiency (CPHD), diabetes insipidus, and syndromic features of holoprosencephaly (HPE). This variant was previously reported in a patient with severe holoprosencephaly and shown to affect TGIF1 function. A novel heterozygous TGIF1 variant (c.82T>C:p.Ser28Pro) was identified in a patient with CPHD, pituitary aplasia and ectopic posterior lobe. Both TGIF1 variants have an autosomal dominant pattern of inheritance with incomplete penetrance. In conclusion, we have found allelic variants in three genes in hypopituitarism patients. We discuss these variants and associated patient phenotypes in relation to previously reported variants in these genes, expanding our knowledge of the phenotypic spectrum in patient populations.


Assuntos
Alelos , Proteínas de Homeodomínio/genética , Hormônio do Crescimento Humano/genética , Hipopituitarismo/genética , Fenótipo , Proteínas Repressoras/genética , Fatores de Transcrição SOXB1/genética , Criança , Pré-Escolar , Feminino , Genótipo , Humanos , Hipopituitarismo/diagnóstico por imagem , Lactente , Imageamento por Ressonância Magnética , Masculino , Mutação , Linhagem
6.
Am J Hum Genet ; 108(8): 1526-1539, 2021 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-34270938

RESUMO

Pituitary hormone deficiency occurs in ∼1:4,000 live births. Approximately 3% of the cases are due to mutations in the alpha isoform of POU1F1, a pituitary-specific transcriptional activator. We found four separate heterozygous missense variants in unrelated individuals with hypopituitarism that were predicted to affect a minor isoform, POU1F1 beta, which can act as a transcriptional repressor. These variants retain repressor activity, but they shift splicing to favor the expression of the beta isoform, resulting in dominant-negative loss of function. Using a high-throughput splicing reporter assay, we tested 1,070 single-nucleotide variants in POU1F1. We identified 96 splice-disruptive variants, including 14 synonymous variants. In separate cohorts, we found two additional synonymous variants nominated by this screen that co-segregate with hypopituitarism. This study underlines the importance of evaluating the impact of variants on splicing and provides a catalog for interpretation of variants of unknown significance in POU1F1.


Assuntos
Ensaios de Triagem em Larga Escala/métodos , Hipopituitarismo/patologia , Mutação , Hormônios Hipofisários/deficiência , Splicing de RNA/genética , Fator de Transcrição Pit-1/genética , Adolescente , Adulto , Criança , Pré-Escolar , Humanos , Hipopituitarismo/etiologia , Hipopituitarismo/metabolismo , Masculino , Linhagem
7.
Nat Commun ; 12(1): 3876, 2021 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-34162856

RESUMO

Testicular development and function rely on interactions between somatic cells and the germline, but similar to other organs, regenerative capacity declines in aging and disease. Whether the adult testis maintains a reserve progenitor population remains uncertain. Here, we characterize a recently identified mouse testis interstitial population expressing the transcription factor Tcf21. We found that TCF21lin cells are bipotential somatic progenitors present in fetal testis and ovary, maintain adult testis homeostasis during aging, and act as potential reserve somatic progenitors following injury. In vitro, TCF21lin cells are multipotent mesenchymal progenitors which form multiple somatic lineages including Leydig and myoid cells. Additionally, TCF21+ cells resemble resident fibroblast populations reported in other organs having roles in tissue homeostasis, fibrosis, and regeneration. Our findings reveal that the testis, like other organs, maintains multipotent mesenchymal progenitors that can be potentially leveraged in development of future therapies for hypoandrogenism and/or infertility.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Diferenciação Celular/genética , Homeostase/genética , Células-Tronco Mesenquimais/metabolismo , Regeneração/genética , Testículo/metabolismo , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Linhagem da Célula/genética , Células Cultivadas , Feminino , Perfilação da Expressão Gênica/métodos , Células Intersticiais do Testículo/citologia , Células Intersticiais do Testículo/metabolismo , Masculino , Células-Tronco Mesenquimais/citologia , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Análise de Célula Única/métodos , Testículo/citologia
8.
Eur J Endocrinol ; 185(1): 121-135, 2021 05 25.
Artigo em Inglês | MEDLINE | ID: mdl-33950863

RESUMO

Objective: The transcription factor OTX2 is implicated in ocular, craniofacial, and pituitary development. Design: We aimed to establish the contribution of OTX2 mutations in congenital hypopituitarism patients with/without eye abnormalities, study functional consequences, and establish OTX2 expression in the human brain, with a view to investigate the mechanism of action. Methods: We screened patients from the UK (n = 103), international centres (n = 24), and Brazil (n = 282); 145 were within the septo-optic dysplasia spectrum, and 264 had no eye phenotype. Transactivation ability of OTX2 variants was analysed in murine hypothalamic GT1-7 neurons. In situ hybridization was performed on human embryonic brain sections. Genetically engineered mice were generated with a series of C-terminal OTX2 variants. Results: Two chromosomal deletions and six haploinsufficient mutations were identified in individuals with eye abnormalities; an affected relative of one patient harboured the same mutation without an ocular phenotype. OTX2 truncations led to significant transactivation reduction. A missense variant was identified in another patient without eye abnormalities; however, studies revealed it was most likely not causative. In the mouse, truncations proximal to aa219 caused anophthalmia, while distal truncations and the missense variant were tolerated. During human embryogenesis, OTX2 was expressed in the posterior pituitary, retina, ear, thalamus, choroid plexus, and partially in the hypothalamus, but not in the anterior pituitary. Conclusions: OTX2 mutations are rarely associated with hypopituitarism in isolation without eye abnormalities, and may be variably penetrant, even within the same pedigree. Our data suggest that the endocrine phenotypes in patients with OTX2 mutations are of hypothalamic origin.


Assuntos
Hipopituitarismo/fisiopatologia , Microftalmia/fisiopatologia , Neurônios/fisiologia , Fatores de Transcrição Otx/genética , Hipófise/fisiopatologia , Displasia Septo-Óptica/fisiopatologia , Adolescente , Animais , Animais Geneticamente Modificados , Brasil , Linhagem Celular , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Humanos , Hipopituitarismo/embriologia , Hipopituitarismo/genética , Hipotálamo/citologia , Lactente , Masculino , Camundongos , Microftalmia/embriologia , Microftalmia/genética , Mutação , Neurônios/patologia , Linhagem , Hipófise/embriologia , Hipófise/patologia , Displasia Septo-Óptica/embriologia , Displasia Septo-Óptica/genética , Reino Unido
9.
Arch. endocrinol. metab. (Online) ; 61(6): 633-636, Dec. 2017. graf
Artigo em Inglês | LILACS | ID: biblio-887602

RESUMO

SUMMARY Isolated growth hormone deficiency (IGHD) is the most common pituitary hormone deficiency and, clinically, patients have delayed bone age. High sequence similarity between CYP21A2 gene and CYP21A1P pseudogene poses difficulties for exome sequencing interpretation. A 7.5 year-old boy born to second-degree cousins presented with severe short stature (height SDS −3.7) and bone age of 6 years. Clonidine and combined pituitary stimulation tests revealed GH deficiency. Pituitary MRI was normal. The patient was successfully treated with rGH. Surprisingly, at 10.8 years, his bone age had advanced to 13 years, but physical exam, LH and testosterone levels remained prepubertal. An ACTH stimulation test disclosed a non-classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency explaining the bone age advancement and, therefore, treatment with cortisone acetate was added. The genetic diagnosis of a homozygous mutation in GHRHR (p.Leu144His), a homozygous CYP21A2 mutation (p.Val282Leu) and CYP21A1P pseudogene duplication was established by Sanger sequencing, MLPA and whole-exome sequencing. We report the unusual clinical presentation of a patient born to consanguineous parents with two recessive endocrine diseases: non-classic congenital adrenal hyperplasia modifying the classical GH deficiency phenotype. We used a method of paired read mapping aided by neighbouring mis-matches to overcome the challenges of exome-sequencing in the presence of a pseudogene.


Assuntos
Humanos , Masculino , Lactente , Criança , Doenças do Desenvolvimento Ósseo/genética , Esteroide 21-Hidroxilase/genética , Receptores de Neuropeptídeos/genética , Hiperplasia Suprarrenal Congênita/genética , Nanismo Hipofisário/genética , Linhagem , Fenótipo , Doenças do Desenvolvimento Ósseo/etiologia , Receptores de Hormônios Reguladores de Hormônio Hipofisário/genética , Hiperplasia Suprarrenal Congênita/complicações , Consanguinidade , Nanismo Hipofisário/complicações , Mutação
10.
Blood Adv ; 1(15): 1037-1046, 2017 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-29296746

RESUMO

The metalloprotease ADAMTS13 cleaves von Willebrand factor (VWF) in circulating blood, limiting the size of VWF multimers and regulating VWF activity. Abnormal regulation of VWF contributes to bleeding and to thrombotic disorders. ADAMTS13 levels in plasma are highly variable among healthy individuals, although the heritability and the genetic determinants of this variation are unclear. We performed genome-wide association studies of plasma ADAMTS13 concentrations in 3244 individuals from 2 independent cohorts of healthy individuals. The heritability of ADAMTS13 levels was between 59.1% (all individuals) and 83.5% (siblings only), whereas tobacco smoking was associated with a decrease in plasma ADAMTS13 levels. Meta-analysis identified common variants near the ADAMTS13 locus on chromosome 9q34.2 that were significantly associated with ADAMTS13 levels and collectively explained 20.0% of the variance. The top single nucleotide polymorphism (SNP), rs28673647, resides in an intron of ADAMTS13 (ß, 6.7%; P = 1.3E-52). Conditional analysis revealed 3 additional independent signals represented by rs3739893 (ß, -22.3%; P = 1.2E-30) and rs3124762 (ß, 3.5%; P = 8.9E-9) close to ADAMTS13 and rs4075970 (ß, 2.4%; P = 6.8E-9) on 21q22.3. Linkage analysis also identified the region around ADAMTS13 (9q34.2) as the top signal (LOD 3.5), consistent with our SNP association analyses. Two nonsynonymous ADAMTS13 variants in the top 2 independent linkage disequilibrium blocks (Q448E and A732V) were identified and characterized in vitro. This study uncovered specific common genetic polymorphisms that are key genetic determinants of the variation in plasma ADAMTS13 levels in healthy individuals.

11.
Arch Endocrinol Metab ; 61(6): 633-636, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29412390

RESUMO

Isolated growth hormone deficiency (IGHD) is the most common pituitary hormone deficiency and, clinically, patients have delayed bone age. High sequence similarity between CYP21A2 gene and CYP21A1P pseudogene poses difficulties for exome sequencing interpretation. A 7.5 year-old boy born to second-degree cousins presented with severe short stature (height SDS -3.7) and bone age of 6 years. Clonidine and combined pituitary stimulation tests revealed GH deficiency. Pituitary MRI was normal. The patient was successfully treated with rGH. Surprisingly, at 10.8 years, his bone age had advanced to 13 years, but physical exam, LH and testosterone levels remained prepubertal. An ACTH stimulation test disclosed a non-classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency explaining the bone age advancement and, therefore, treatment with cortisone acetate was added. The genetic diagnosis of a homozygous mutation in GHRHR (p.Leu144His), a homozygous CYP21A2 mutation (p.Val282Leu) and CYP21A1P pseudogene duplication was established by Sanger sequencing, MLPA and whole-exome sequencing. We report the unusual clinical presentation of a patient born to consanguineous parents with two recessive endocrine diseases: non-classic congenital adrenal hyperplasia modifying the classical GH deficiency phenotype. We used a method of paired read mapping aided by neighbouring mis-matches to overcome the challenges of exome-sequencing in the presence of a pseudogene.


Assuntos
Hiperplasia Suprarrenal Congênita/genética , Doenças do Desenvolvimento Ósseo/genética , Nanismo Hipofisário/genética , Receptores de Neuropeptídeos/genética , Receptores de Hormônios Reguladores de Hormônio Hipofisário/genética , Esteroide 21-Hidroxilase/genética , Hiperplasia Suprarrenal Congênita/complicações , Doenças do Desenvolvimento Ósseo/etiologia , Criança , Consanguinidade , Nanismo Hipofisário/complicações , Humanos , Recém-Nascido , Masculino , Mutação , Linhagem , Fenótipo
12.
Clin Endocrinol (Oxf) ; 85(3): 408-14, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27000987

RESUMO

INTRODUCTION: Mutations in the transcription factor HESX1 can cause isolated growth hormone deficiency (IGHD) or combined pituitary hormone deficiency (CPHD) with or without septo-optic dysplasia (SOD). So far there is no clear genotype-phenotype correlation. PATIENTS AND RESULTS: We report four different recessive loss-of-function mutations in three unrelated families with CPHD and no midline defects or SOD. A homozygous p.R160C mutation was found by Sanger sequencing in two siblings from a consanguineous family. These patients presented with ACTH, TSH and GH deficiencies, severe anterior pituitary hypoplasia (APH) or pituitary aplasia (PA) and normal posterior pituitary. The p.R160C mutation was previously reported in a case with SOD, CPHD and ectopic posterior pituitary (EPP). Using exome sequencing, a homozygous p.I26T mutation was found in a Brazilian patient born to consanguineous parents. This patient had evolving CPHD, normal ACTH, APH and normal posterior pituitary (NPP). A previously reported patient homozygous for p.I26T had evolving CPHD and EPP. Finally, we identified compound heterozygous mutations in HESX1, p.[R159W];[R160H], in a patient with PA and CPHD. We showed that both of these mutations abrogate the ability of HESX1 to repress PROP1-mediated transcriptional activation. A patient homozygous for p.R160H was previously reported in a patient with CPHD, EPP, APH. CONCLUSION: These three examples demonstrate that HESX1 mutations cause variable clinical features in patients, which suggests an influence of modifier genes or environmental factors on the phenotype.


Assuntos
Proteínas de Homeodomínio/genética , Hipopituitarismo/genética , Mutação , Adolescente , Sequência de Bases , Brasil , Família , Feminino , Estudos de Associação Genética , Humanos , Hipopituitarismo/diagnóstico , Recém-Nascido , Masculino , Oriente Médio , Linhagem
13.
Blood ; 124(20): 3155-64, 2014 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-25208887

RESUMO

Plasminogen is the precursor of the serine protease plasmin, a central enzyme of the fibrinolytic system. Plasma levels of plasminogen vary by almost 2-fold among healthy individuals, yet little is known about its heritability or genetic determinants in the general population. In order to identify genetic factors affecting the natural variation of plasminogen levels, we performed a genome-wide association study and linkage analysis in a sample of 3456 young healthy individuals who participated in the Genes and Blood Clotting Study (GABC) or the Trinity Student Study (TSS). Heritability of plasminogen levels was 48.1% to 60.0%. Tobacco smoking and female sex were associated with higher levels of plasminogen. In the meta-analysis, 11 single-nucleotide polymorphisms (SNPs) in 2 regions reached genome-wide significance (P < 5.0E-8). Of these, 9 SNPs were near the PLG or LPA genes on Chr6q26, whereas 2 were on Chr19q13 and 5' upstream of SIGLEC14. These 11 SNPs represented 4 independent signals and collectively explained 6.8% of plasminogen level variation in the study populations. The strongest association was observed for a nonsynonymous SNP in the PLG gene (R523W). Individuals bearing an additional copy of this allele had an average decrease of 13.4% in plasma plasminogen level.


Assuntos
Apolipoproteínas A/genética , Lectinas/genética , Plasminogênio/análise , Plasminogênio/genética , Receptores de Superfície Celular/genética , Fumar/sangue , Adolescente , Adulto , Estudos de Coortes , Feminino , Deleção de Genes , Ligação Genética , Variação Genética , Estudo de Associação Genômica Ampla , Humanos , Masculino , Polimorfismo de Nucleotídeo Único , Adulto Jovem
14.
J Nutr ; 141(5): 828-34, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21430251

RESUMO

We previously reported that (-)-epigallocatechin-3-gallate (EGCG) and grape seed extract (GSE) at high concentration nearly blocked intestinal iron transport across the enterocyte. In this study, we aimed to determine whether small amounts of EGCG, GSE, and green tea extract (GT) are capable of inhibiting iron absorption, to examine if ascorbic acid counteracts the inhibitory action of polyphenols on iron absorption, and to explore the mechanisms of polyphenol-mediated apical iron uptake and basolateral iron release. An(55)Fe absorption study was conducted by adding various concentrations of EGCG, GSE, and GT using Caco-2 intestinal cells. Polyphenols were found to inhibit the transepithelial (55)Fe transport in a dose-dependent manner. The addition of ascorbic acid offset the inhibitory effects of polyphenols on iron transport. Ascorbic acid modulated the transepithelial iron transport without changing the apical iron uptake and the expression of ferroportin-1 protein in the presence of EGCG. The polyphenol-mediated apical iron uptake was inhibited by membrane impermeable Fe(2+) chelators (P < 0.001), but at a low temperature (4°C), the apical iron uptake was still higher than the control values at 37°C (P < 0.001). These results suggest that polyphenols enhance the apical iron uptake partially by reducing the conversion of ferric to ferrous ions and possibly by increasing the uptake of polyphenol-iron complexes via the energy-independent pathway. The present results indicate that the inhibitory effects of dietary polyphenols on iron absorption can be offset by ascorbic acid. Further studies are needed to confirm the current findings in vivo.


Assuntos
Ácido Ascórbico , Dieta/efeitos adversos , Enterócitos/metabolismo , Flavonoides/efeitos adversos , Absorção Intestinal , Ferro da Dieta/metabolismo , Fenóis/efeitos adversos , Transporte Biológico/efeitos dos fármacos , Células CACO-2 , Catequina/efeitos adversos , Catequina/análogos & derivados , Catequina/antagonistas & inibidores , Catequina/metabolismo , Proteínas de Transporte de Cátions/metabolismo , Polaridade Celular , Temperatura Baixa , Suplementos Nutricionais/efeitos adversos , Enterócitos/efeitos dos fármacos , Flavonoides/antagonistas & inibidores , Flavonoides/metabolismo , Extrato de Sementes de Uva/efeitos adversos , Extrato de Sementes de Uva/antagonistas & inibidores , Extrato de Sementes de Uva/metabolismo , Humanos , Quelantes de Ferro/farmacologia , Radioisótopos de Ferro , Oxirredução , Fenóis/antagonistas & inibidores , Fenóis/metabolismo , Extratos Vegetais/efeitos adversos , Extratos Vegetais/antagonistas & inibidores , Extratos Vegetais/metabolismo , Polifenóis , Chá/química
15.
J Food Sci ; 76(5): H143-50, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22417433

RESUMO

UNLABELLED: Although heme iron is an important form of dietary iron, its intestinal absorption mechanism remains elusive. Our previous study revealed that (-)-epigallocatechin-3-gallate (EGCG) and grape seed extract (GSE) markedly inhibited intestinal heme iron absorption by reducing the basolateral iron export in Caco-2 cells. The aim of this study was to examine whether small amounts of EGCG, GSE, and green tea extract (GT) could inhibit heme iron absorption, and to test whether the inhibitory action of polyphenols could be offset by ascorbic acid. A heme-55Fe absorption study was conducted by adding various concentrations of EGCG, GSE, and GT to Caco-2 cells in the absence and presence of ascorbic acid. Polyphenolic compounds significantly inhibited heme-55Fe absorption in a dose-dependent manner. The addition of ascorbic acid did not modulate the inhibitory effect of dietary polyphenols on heme iron absorption when the cells were treated with polyphenols at a concentration of 46 mg/L. However, ascorbic acid was able to offset or reverse the inhibitory effects of polyphenolic compounds when lower concentrations of polyphenols were added (≤ 4.6 mg/L). Ascorbic acid modulated the heme iron absorption without changing the apical heme uptake, the expression of the proteins involved in heme metabolism and basolateral iron transport, and heme oxygenase activity, indicating that ascorbic acid may enhance heme iron absorption by modulating the intracellular distribution of 55Fe. These results imply that the regular consumption of dietary ascorbic acid can easily counteract the inhibitory effects of low concentrations of dietary polyphenols on heme iron absorption but cannot counteract the inhibitory actions of high concentrations of polyphenols. PRACTICAL APPLICATION: Bioactive dietary polyphenols inhibit heme iron absorption in a dose-dependent manner. The small amounts of polyphenolic compounds present in foods are capable of reducing heme iron transport across the intestinal enterocyte. However, the inhibitory effects of dietary polyphenolic compounds on heme iron absorption can be offset by ascorbic acid and can possibly be avoided by decreasing the consumption of polyphenols while simultaneously taking ascorbic acid.


Assuntos
Dieta , Absorção Intestinal/efeitos dos fármacos , Intestinos/citologia , Ferro da Dieta/sangue , Extratos Vegetais/farmacologia , Polifenóis/farmacologia , Animais , Antioxidantes/farmacologia , Ácido Ascórbico/metabolismo , Transporte Biológico/efeitos dos fármacos , Células CACO-2 , Catequina/análogos & derivados , Catequina/farmacologia , Relação Dose-Resposta a Droga , Enterócitos/efeitos dos fármacos , Enterócitos/metabolismo , Extrato de Sementes de Uva/farmacologia , Heme/metabolismo , Humanos , Mucosa Intestinal/metabolismo , Intestinos/efeitos dos fármacos , Ferro da Dieta/antagonistas & inibidores , Camundongos , Chá/química
16.
J Nutr ; 140(6): 1117-21, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20375262

RESUMO

Because dietary polyphenolic compounds have a wide range of effects in vivo and vitro, including chelation of metals such as iron, it is prudent to test whether the regular consumption of dietary bioactive polyphenols impair the utilization of dietary iron. Because our previous study showed the inhibitory effect of (-) -epigallocatechin-3-gallate (EGCG) and grape seed extract (GSE) on nonheme iron absorption, we investigated whether EGCG and GSE also affect iron absorption from heme. The fully differentiated intestinal Caco-2 cells grown on microporous membrane inserts were incubated with heme (55)Fe in uptake buffer containing EGCG or GSE in the apical compartment for 7 h. Both EGCG and GSE decreased (P < 0.05) transepithelial transport of heme-derived iron. However, apical heme iron uptake was increased (P < 0.05) by GSE. Despite the increased cellular levels of heme (55)Fe, the transfer of iron across the intestinal basolateral membrane was extremely low, indicating that basolateral export was impaired by GSE. In contrast, EGCG moderately decreased the cellular assimilation of heme (55)Fe, but the basolateral iron transfer was extremely low, suggesting that the basolateral efflux of heme iron was also inhibited by EGCG. Expression of heme oxygenase, ferroportin, and hephaestin protein was not changed by EGCG and GSE. The apical uptake of heme iron was temperature dependent and saturable in fully differentiated Caco-2 cells. Our data show that bioactive dietary polyphenols inhibit heme iron absorption mainly by reducing basolateral iron exit rather than decreasing apical heme iron uptake in intestinal cells.


Assuntos
Flavonoides/farmacologia , Heme/metabolismo , Intestinos/citologia , Ferro/metabolismo , Fenóis/farmacologia , Absorção , Transporte Biológico , Células CACO-2 , Catequina/análogos & derivados , Catequina/farmacologia , Extrato de Sementes de Uva/farmacologia , Humanos , Polifenóis
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