RESUMO
AIM: Thyroid hormones regulate metabolic response. While triiodothyronine (T3) is usually considered to be the active form of thyroid hormone, one form of diiodothyronine (3,5-T2) exerts T3-like effects on energy consumption and lipid metabolism. 3,5-T2 also improves glucose tolerance in rats and 3,5-T2 levels correlate with fasting glucose in humans. Presently, however, little is known about mechanisms of 3,5-T2 effects on glucose metabolism. Here, we set out to compare effects of T3, 3,5-T2 and another form of T2 (3,3-T2) in a mouse model of diet-induced obesity and determined effects of T3 and 3,5-T2 on markers of classical insulin sensitization to understand how diiodothyronines influence blood glucose. METHODS: Cell- and protein-based assays of thyroid hormone action. Assays of metabolic parameters in mice. Analysis of transcript and protein levels in different tissues by qRT-PCR and Western blot. RESULTS: T3 and 3,5-T2 both reduce body weight, adiposity and body temperature despite increased food intake. 3,3'-T2 lacks these effects. T3 and 3,5-T2 reduce blood glucose levels, whereas 3,3'-T2 worsens glucose tolerance. Neither T3 nor 3,5-T2 affects markers of insulin sensitization in skeletal muscle or white adipose tissue (WAT), but both reduce hepatic GLUT2 glucose transporter levels and glucose output. T3 and 3,5-T2 also induce expression of mitochondrial uncoupling proteins (UCPs) 3 and 1 in skeletal muscle and WAT respectively. CONCLUSIONS: 3,5-T2 influences glucose metabolism in a manner that is distinct from insulin sensitization and involves reductions in hepatic glucose output and changes in energy utilization.
Assuntos
Glicemia/efeitos dos fármacos , Di-Iodotironinas/farmacologia , Resistência à Insulina , Animais , Dieta Hiperlipídica , Metabolismo Energético/efeitos dos fármacos , Células Hep G2 , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Obesidade , Tri-Iodotironina/farmacologiaRESUMO
Thyroid hormone receptors (TRs) are ligand-gated transcription factors with critical roles in development and metabolism. Although x-ray structures of TR ligand-binding domains (LBDs) with agonists are available, comparable structures without ligand (apo-TR) or with antagonists are not. It remains important to understand apo-LBD conformation and the way that it rearranges with ligands to develop better TR pharmaceuticals. In this study, we conducted hydrogen/deuterium exchange on TR LBDs with or without agonist (T(3)) or antagonist (NH3). Both ligands reduce deuterium incorporation into LBD amide hydrogens, implying tighter overall folding of the domain. As predicted, mass spectroscopic analysis of individual proteolytic peptides after hydrogen/deuterium exchange reveals that ligand increases the degree of solvent protection of regions close to the buried ligand-binding pocket. However, there is also extensive ligand protection of other regions, including the dimer surface at H10-H11, providing evidence for allosteric communication between the ligand-binding pocket and distant interaction surfaces. Surprisingly, C-terminal activation helix H12, which is known to alter position with ligand, remains relatively protected from solvent in all conditions suggesting that it is packed against the LBD irrespective of the presence or type of ligand. T(3), but not NH3, increases accessibility of the upper part of H3-H5 to solvent, and we propose that TR H12 interacts with this region in apo-TR and that this interaction is blocked by T(3) but not NH3. We present data from site-directed mutagenesis experiments and molecular dynamics simulations that lend support to this structural model of apo-TR and its ligand-dependent conformational changes.
Assuntos
Medição da Troca de Deutério , Receptores dos Hormônios Tireóideos/agonistas , Receptores dos Hormônios Tireóideos/antagonistas & inibidores , Sequência de Aminoácidos , Amônia/farmacologia , Apoproteínas/química , Apoproteínas/metabolismo , Deutério/metabolismo , Humanos , Ligantes , Simulação de Dinâmica Molecular , Dados de Sequência Molecular , Mutação/genética , Peptídeos/química , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Receptores dos Hormônios Tireóideos/química , Alinhamento de Sequência , Solventes , Tri-Iodotironina/farmacologiaRESUMO
Thyroid hormone receptors (TR) play critical roles in virtually all tissues. The TR ligand-binding domain (LBD) participates in important activities, such as transcriptional activation and repression, through conformational changes induced by hormone binding. Two crystal forms of isoform alpha1 of the human thyroid hormone receptor LBD (hTRalpha1) in complex with the thyroid hormones T3 and Triac were obtained. The hTRalpha1-T3 complex was crystallized in a previously unobserved crystal form (space group P2(1)2(1)2(1), a = 59.98, b = 80.80, c = 102.21 A), with diffraction patterns extending to 1.90 A resolution on a rotating-anode X-ray source, and in space group C2 (a = 117.54, b = 80.66, c = 62.55 A, beta = 121.04 degrees), with data extending to 2.32 A resolution. The hTRalpha1-Triac complex was also crystallized in the new space group P2(1)2(1)2(1), with unit-cell parameters a = 60.01, b = 80.82, c = 102.39 A; its resolution limit extended to 2.20 A on a home source. Phasing was carried out by the molecular-replacement method and structural refinement is currently in progress. The refined structures may provide insight into the design of new thyromimetics.
Assuntos
Receptores dos Hormônios Tireóideos/química , Cristalização , Cristalografia por Raios X , Humanos , Ligantes , Modelos Moleculares , Ligação Proteica , Conformação Proteica , Isoformas de Proteínas , Estrutura Terciária de Proteína , Software , Temperatura , Difração de Raios XRESUMO
An ELISA was compared with the plaque-reduction serum neutralization (PRSN) test, for detection of vesicular stomatitis virus (VSV) antibodies in cattle in a vesicular stomatitis enzootic region of Mexico. A total of 325 bovine serum samples were screened for VSV antibodies. The PRSN test was performed, using Vero cells. The ELISA contained gradient-purified VSV Indiana (Lab strain) and VSV New Jersey (Hazelhurst) as the antigens. Regression analysis and weighted kappa statistic were used to estimate measures of agreement between the 2 assays for detection of VSV antibodies. The ELISA method proved useful for serodiagnosis of vesicular stomatitis. The ELISA and PRSN test results were highly correlated for detection of VSV antibodies.
Assuntos
Anticorpos Antivirais/sangue , Doenças dos Bovinos/diagnóstico , Estomatite/veterinária , Vírus da Estomatite Vesicular Indiana/imunologia , Vesiculovirus , Viroses/veterinária , Animais , Antígenos Virais/imunologia , Bovinos , Doenças dos Bovinos/epidemiologia , Ensaio de Imunoadsorção Enzimática , Estudos de Avaliação como Assunto , México/epidemiologia , Testes de Neutralização , Valor Preditivo dos Testes , Análise de Regressão , Reprodutibilidade dos Testes , Estomatite/diagnóstico , Estomatite/epidemiologia , Células Vero , Viroses/diagnóstico , Viroses/epidemiologiaAssuntos
Febres Hemorrágicas Virais/epidemiologia , Adulto , Animais , Anticorpos Antivirais/análise , Arbovírus/isolamento & purificação , Autopsia , Sangue/microbiologia , Bolívia , Linhagem Celular , Células Cultivadas , Testes de Fixação de Complemento , Cricetinae , Feminino , Imunofluorescência , Febres Hemorrágicas Virais/microbiologia , Humanos , Fígado/microbiologia , Masculino , Camundongos , Testes de Neutralização , Faringe/microbiologia , Baço/microbiologiaAssuntos
Arbovírus , Animais , Antígenos/análise , Arbovírus/análise , Arbovírus/classificação , Arbovírus/efeitos dos fármacos , Arbovírus/crescimento & desenvolvimento , Arbovírus/imunologia , Arbovírus/isolamento & purificação , Arbovírus/patogenicidade , Linhagem Celular , Centrifugação com Gradiente de Concentração , Césio , Cloretos , Clorofórmio/farmacologia , Testes de Fixação de Complemento , Cricetinae , Imunofluorescência , Haplorrinos , Humanos , Soros Imunes , Imunodifusão , Rim , Camundongos , Testes de Sensibilidade Microbiana , Paraguai , RNA Viral/análise , Coelhos , RoedoresAssuntos
Anticorpos , Febres Hemorrágicas Virais/imunologia , Adsorção , Animais , Formação de Anticorpos , Testes de Fixação de Complemento , Cricetinae , Técnicas de Cultura , Cobaias , Haplorrinos , Humanos , Concentração de Íons de Hidrogênio , Métodos , Camundongos , Testes de Neutralização , Vírus de RNA/imunologia , Coelhos , Ratos , Fatores de TempoAssuntos
Febres Hemorrágicas Virais , Roedores , Animais , Anticorpos/análise , Bolívia , Testes de Fixação de Complemento , Geografia , Febres Hemorrágicas Virais/epidemiologia , Febres Hemorrágicas Virais/imunologia , Humanos , Testes de Neutralização , Vírus/imunologia , Vírus/isolamento & purificação , ZoonosesRESUMO
South American hemorrhagic fever viruses most certainly appear to be rodent-associated; any current effort to prevent human infection, therefore, should be directed at interrupting the transmission of virus, directly or indirectly, from rodents to humans. It is unlikely that any single means of rodent control would be effective in all situations
The development of a Machupo virus vaccine would be of great value, not only to Bolivians, but to laboratory workers outside of Bolivia. But is seems that the most acute need is for the protection of Argentine ...(AU)
Publicado en inglés en la Serie de Publicaciones Científicas de la OPS 147:260-265, 1967
Several approaches to rodent control are possible and methods need to be tailored to each local situation, but only after determining what the host-reservoir is, and the mode of virus transmission. Differences in human activities can be most striking among South American communities. In Bolivia, for example, the populations which are at risk live in areas in which there are no roads and travel is chiefly by oxcart trail or riverboat. Thus, most residents of north-eastern Bolivia never leave the province in which they were born, and there is little population movement over distances greater than 50 miles. In cotrast, the epidemic area of Argentina is laced with highways and railroads; a great deal of farm work is done by migratory labor and it is likely that large numbers of new susceptibles are fed into the hemorrhagic fever areas each year