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1.
Cell ; 166(4): 867-880, 2016 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-27518562

RESUMO

We report that astrocytic insulin signaling co-regulates hypothalamic glucose sensing and systemic glucose metabolism. Postnatal ablation of insulin receptors (IRs) in glial fibrillary acidic protein (GFAP)-expressing cells affects hypothalamic astrocyte morphology, mitochondrial function, and circuit connectivity. Accordingly, astrocytic IR ablation reduces glucose-induced activation of hypothalamic pro-opio-melanocortin (POMC) neurons and impairs physiological responses to changes in glucose availability. Hypothalamus-specific knockout of astrocytic IRs, as well as postnatal ablation by targeting glutamate aspartate transporter (GLAST)-expressing cells, replicates such alterations. A normal response to altering directly CNS glucose levels in mice lacking astrocytic IRs indicates a role in glucose transport across the blood-brain barrier (BBB). This was confirmed in vivo in GFAP-IR KO mice by using positron emission tomography and glucose monitoring in cerebral spinal fluid. We conclude that insulin signaling in hypothalamic astrocytes co-controls CNS glucose sensing and systemic glucose metabolism via regulation of glucose uptake across the BBB.


Assuntos
Astrócitos/metabolismo , Glucose/metabolismo , Hipotálamo/metabolismo , Insulina/metabolismo , Transdução de Sinais , Sistema X-AG de Transporte de Aminoácidos/genética , Sistema X-AG de Transporte de Aminoácidos/metabolismo , Animais , Barreira Hematoencefálica , Retículo Endoplasmático/metabolismo , Proteína Glial Fibrilar Ácida/genética , Proteína Glial Fibrilar Ácida/metabolismo , Homeostase , Camundongos , Mitocôndrias/metabolismo , Neurônios/citologia , Neurônios/metabolismo , Pró-Opiomelanocortina/metabolismo , Receptor de Insulina/genética , Receptor de Insulina/metabolismo
2.
Molecules ; 28(5)2023 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-36903408

RESUMO

Here we present an approach to functionalize silanized single-walled carbon nanotubes (SWNTs) through copper-free click chemistry for the assembly of inorganic and biological nanohybrids. The nanotube functionalization route involves silanization and strain-promoted azide-alkyne cycloaddition reactions (SPACC). This was characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and Fourier transform infra-red spectroscopy. Silane-azide-functionalized SWNTs were immobilized from solution onto patterned substrates through dielectrophoresis (DEP). We demonstrate the general applicability of our strategy for the functionalization of SWNTs with metal nanoparticles (gold nanoparticles), fluorescent dyes (Alexa Fluor 647) and biomolecules (aptamers). In this regard, dopamine-binding aptamers were conjugated to the functionalized SWNTs to perform real-time detection of dopamine at different concentrations. Additionally, the chemical route is shown to selectively functionalize individual nanotubes grown on the surface of silicon substrates, contributing towards future nano electronic device applications.


Assuntos
Nanopartículas Metálicas , Nanotubos de Carbono , Nanotubos de Carbono/química , Ouro , Azidas/química , Dopamina
3.
Phys Chem Chem Phys ; 24(6): 3780-3787, 2022 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-35084003

RESUMO

We present a joint experimental and theoretical characterization of the magnetic properties of coordination clusters with an antiferromagnetic core of four magnetic ions. Two different compounds are analyzed, with Co and Mn ions in the core. While both molecules are antiferromagnetic, they display different sensitivities to external magnetic field, according to the different atomic magnetic moments and strength of the intra-molecular magnetic couplings. In particular, the dependence of the magnetization versus field of the two molecules switches with temperature: at low temperature the magnetization is smaller in {Mn4} than in Co4, while the opposite happens at high temperature. Through a detailed analysis of the electronic and magnetic properties of the two compounds we identify a stronger magnetic interaction between the magnetic ions in {Mn4} with respect to {Co4}. Moreover {Co4} displays not negligible spin-orbit related effects that could affect the spin lifetime in future antiferromagnetic spintronic applications. We highlight the necessity to account for these spin-orbit effects together with electronic correlation effects for a reliable description of these compounds.

4.
Nanotechnology ; 28(43): 435703, 2017 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-28885185

RESUMO

Endohedral lanthanide ions packed inside carbon nanotubes (CNTs) in a one-dimensional assembly have been studied with a combination of high resolution transmission electron microscopy (HRTEM), scanning transmission x-ray microscopy (STXM), and x-ray magnetic circular dichroism (XMCD). By correlating HRTEM and STXM images we show that structures down to 30 nm are resolved with chemical contrast and record x-ray absorption spectra from endohedral lanthanide ions embedded in individual nanoscale CNT bundles. XMCD measurements of an Er3N@C80 bulk sample and a macroscopic assembly of filled CNTs indicate that the magnetic properties of the endohedral Er3+ ions are unchanged when encapsulated in CNTs. This study demonstrates the feasibility of local magnetic x-ray characterisation of low concentrations of lanthanide ions embedded in molecular nanostructures.

5.
Naturwissenschaften ; 101(11): 1003-6, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25142634

RESUMO

The grey short-tailed opossum, Monodelphis domestica, has been an established research animal for more than five decades, but relatively, little is known about its thermophysiology. Here we studied core body temperature (T b) and metabolic rate (MR) of female adult M. domestica housed in the laboratory at an ambient temperature (T a) of 26 °C. In expanding previous reports, the average recorded core T b of M. domestica was 34.3 °C. The T b of an individual M. domestica can drop below 30 °C (minimal T b: 28.6 °C) accompanied by a reduction in MR of up to 52 % even while having ad libitum access to food. These findings demonstrate for the first time the presence of spontaneous torpor in M. domestica. Metabolic suppression at relatively high T a and T b furthermore broadens our perspective on the use of torpor as a metabolic strategy not just restricted to cold climates.


Assuntos
Temperatura Alta , Monodelphis/fisiologia , Torpor/fisiologia , Animais , Temperatura Corporal , Feminino
6.
Artigo em Inglês | MEDLINE | ID: mdl-24021912

RESUMO

Small mammals actively decrease metabolism during daily torpor and hibernation to save energy. Recently, depression of mitochondrial substrate oxidation in isolated liver mitochondria was observed and associated to hypothermic/hypometabolic states in Djungarian hamsters, mice and hibernators. We aimed to clarify whether hypothermia or hypometabolism causes mitochondrial depression during torpor by studying the Golden spiny mouse (Acomys russatus), a desert rodent which performs daily torpor at high ambient temperatures of 32°C. Notably, metabolic rate but not body temperature is significantly decreased under these conditions. In isolated liver, heart, skeletal muscle or kidney mitochondria we found no depression of respiration. Moderate cold exposure lowered torpor body temperature but had minor effects on minimal metabolic rate in torpor. Neither decreased body temperature nor metabolic rate impacted mitochondrial respiration. Measurements of mitochondrial proton leak kinetics and determination of P/O ratio revealed no differences in mitochondrial efficiency. Hydrogen peroxide release from mitochondria was not affected. We conclude that interspecies differences of mitochondrial depression during torpor do not support a general relationship between mitochondrial respiration, body temperature and metabolic rate. In Golden spiny mice, reduction of metabolic rate at mild temperatures is not triggered by depression of substrate oxidation as found in liver mitochondria from other cold-exposed rodents.


Assuntos
Metabolismo Basal , Peróxido de Hidrogênio/metabolismo , Mitocôndrias Hepáticas/metabolismo , Murinae/fisiologia , Torpor , Trifosfato de Adenosina/biossíntese , Animais , Temperatura Corporal , Rim/metabolismo , Fígado/metabolismo , Mitocôndrias Cardíacas/metabolismo , Músculo Esquelético/metabolismo , Miocárdio/metabolismo , Especificidade de Órgãos , Consumo de Oxigênio
7.
J Biol Chem ; 285(29): 21961-8, 2010 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-20466728

RESUMO

In thermogenic brown adipose tissue, uncoupling protein 1 (UCP1) catalyzes the dissipation of mitochondrial proton motive force as heat. In a cellular environment of high oxidative capacity such as brown adipose tissue (BAT), mitochondrial uncoupling could also reduce deleterious reactive oxygen species, but the specific involvement of UCP1 in this process is disputed. By comparing brown adipose tissue mitochondria of wild type mice and UCP1-ablated litter mates, we show that UCP1 potently reduces mitochondrial superoxide production after cold acclimation and during fatty acid oxidation. We address the sites of superoxide production and suggest diminished probability of "reverse electron transport" facilitated by uncoupled respiration as the underlying mechanism of reactive oxygen species suppression in BAT. Furthermore, ablation of UCP1 represses the cold-stimulated increase of substrate oxidation normally seen in active BAT, resulting in lower superoxide production, presumably avoiding deleterious oxidative damage. We conclude that UCP1 allows high oxidative capacity without promoting oxidative damage by simultaneously lowering superoxide production.


Assuntos
Tecido Adiposo Marrom/metabolismo , Canais Iônicos/metabolismo , Mitocôndrias/metabolismo , Proteínas Mitocondriais/metabolismo , Superóxidos/metabolismo , Aclimatação , Animais , Respiração Celular , Temperatura Baixa , Complexo I de Transporte de Elétrons/metabolismo , Ácidos Graxos/metabolismo , Temperatura Alta , Malatos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Modelos Biológicos , Oxirredução , Prótons , Ácido Pirúvico/metabolismo , Especificidade por Substrato , Proteína Desacopladora 1
8.
Nano Lett ; 10(11): 4470-4, 2010 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-20942383

RESUMO

We study collective vibrational breathing modes in the Raman spectrum of a multiwalled carbon nanotube. In correlation with high-resolution transmission electron microscopy, we find that these modes have energies differing by more than 23% from the radial breathing modes of the corresponding single-walled nanotubes. This shift in energy is explained with intershell interactions using a model of coupled harmonic oscillators. The strength of this interaction is related to the coupling strength expected for few-layer graphene.


Assuntos
Modelos Químicos , Nanotubos de Carbono/química , Nanotubos de Carbono/ultraestrutura , Simulação por Computador , Luz , Teste de Materiais , Tamanho da Partícula , Porosidade , Espalhamento de Radiação
9.
Materials (Basel) ; 15(1)2021 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-35009192

RESUMO

Here, we present the (element-specific) magnetic properties and cation ordering for ultrathin Co-rich cobalt ferrite films. Two Co-rich CoxFe3-xO4 films with different stoichiometry (x=1.1 and x=1.4) have been formed by reactive solid phase epitaxy due to post-deposition annealing from epitaxial CoO/Fe3O4 bilayers deposited before on Nb-doped SrTiO3(001). The electronic structure, stoichiometry and homogeneity of the cation distribution of the resulting cobalt ferrite films were verified by angle-resolved hard X-ray photoelectron spectroscopy. From X-ray magnetic circular dichroism measurements, the occupancies of the different sublattices were determined using charge-transfer multiplet calculations. For both ferrite films, a partially inverse spinel structure is found with increased amount of Co3+ cations in the low-spin state on octahedral sites for the Co1.4Fe1.6O4 film. These findings concur with the results obtained by superconducting quantum interference device measurements. Further, the latter measurements revealed the presence of an additional soft magnetic phase probably due to cobalt ferrite islands emerging from the surface, as suggested by atomic force microscope measurements.

10.
Elife ; 102021 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-33513092

RESUMO

Insights into the conformational organization and dynamics of proteins complexes at membranes is essential for our mechanistic understanding of numerous key biological processes. Here, we introduce graphene-induced energy transfer (GIET) to probe axial orientation of arrested macromolecules at lipid monolayers. Based on a calibrated distance-dependent efficiency within a dynamic range of 25 nm, we analyzed the conformational organization of proteins and complexes involved in tethering and fusion at the lysosome-like yeast vacuole. We observed that the membrane-anchored Rab7-like GTPase Ypt7 shows conformational reorganization upon interactions with effector proteins. Ensemble and time-resolved single-molecule GIET experiments revealed that the HOPS tethering complex, when recruited via Ypt7 to membranes, is dynamically alternating between a 'closed' and an 'open' conformation, with the latter possibly interacting with incoming vesicles. Our work highlights GIET as a unique spectroscopic ruler to reveal the axial orientation and dynamics of macromolecular complexes at biological membranes with sub-nanometer resolution.


Proteins are part of the building blocks of life and are essential for structure, function and regulation of every cell, tissue and organ of the body. Proteins adopt different conformations to work efficiently within the various environments of a cell. They can also switch between shapes. One way to monitor how proteins change their shapes involves energy transfer. This approach can measure how close two proteins, or two parts of the same protein, are, by using dye labels that respond to each other when they are close together. For example, in a method called FRET, one dye label absorbs light and transfers the energy to the other label, which emits it as a different color of light. However, FRET only works over short distances (less than 10nm apart or 1/100,000th of a millimeter), so it is not useful for larger proteins. Here, Füllbrunn, Li et al. developed a method called GIET that uses graphene to analyze the dynamic structures of proteins on membrane surfaces. Graphene is a type of carbon nanomaterial that can absorb energy from dye labels and could provide a way to study protein interactions over longer distances. Graphene was deposited on a glass surface where it was coated with single layer of membrane, which could then be used to capture specific proteins. The results showed that GIET worked over longer distances (up to 30 nm) than FRET and could be used to study proteins attached to the membrane around graphene. Füllbrunn, Li et al. used it to examine a specific complex of proteins called HOPS, which is linked to multiple diseases, including Ebola, measuring distances between the head or tail of HOPS and the membrane to understand protein shapes. This revealed that HOPS adopts an upright position on membranes and alternates between open and closed shapes. The study of Füllbrunn, Li et al. highlights the ability of GIET to address unanswered questions about the function of protein complexes on membrane surfaces and sheds new light on the structural dynamics of HOPS in living cells. As it allows protein interactions to be studied over much greater distances, GIET could be a powerful new tool for cell biology research. Moreover, graphene is also useful in electron microscopy and both approaches combined could achieve a detailed structural picture of proteins in action.


Assuntos
Membrana Celular/metabolismo , Grafite/metabolismo , Complexos Multiproteicos/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/fisiologia , Membrana Celular/ultraestrutura , Saccharomyces cerevisiae/ultraestrutura
11.
Am J Physiol Regul Integr Comp Physiol ; 299(5): R1396-406, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20826705

RESUMO

We compared maximal cold-induced heat production (HPmax) and cold limits between warm (WA; 27°C), moderate cold (MCA; 18°C), or cold acclimated (CA; 5°C) wild-type and uncoupling-protein 1 knockout (UCP1-KO) mice. In wild-type mice, HPmax was successively increased after MCA and CA, and the cold limit was lowered to -8.3°C and -18.0°C, respectively. UCP1-KO mice also increased HPmax in response to MCA and CA, although to a lesser extent. Direct comparison revealed a maximal cold-induced recruitment of heat production by +473 mW and +227 mW in wild-type and UCP1-KO mice, respectively. The increase in cold tolerance of UCP1-KO mice from -0.9°C in MCA to -10.1°C in CA could not be directly related to changes in HPmax, indicating that UCP1-KO mice used the dissipated heat more efficiently than wild-type mice. As judged from respiratory quotients, acutely cold-challenged UCP1-KO mice showed a delayed transition toward lipid oxidation, and 5-h cold exposure revealed diminished physical activity and less variability in the control of metabolic rate. We conclude that BAT is required for maximal adaptive thermogenesis but also allows metabolic flexibility and a rapid switch toward sustained lipid-fuelled thermogenesis as an acute response to cold. In both CA groups, expression of contractile proteins (myosin heavy-chain isoforms) showed minor training effects in skeletal muscles, while cardiac muscle of UCP1-KO mice had novel expression of beta cardiac isoform. Neither respiration nor basal proton conductance of skeletal muscle mitochondria were different between genotypes. In subcutaneous white adipose tissue of UCP1-KO mice, cold exposure increased cytochrome-c oxidase activity and expression of the cell death-inducing DFFA-like effector A by 3.6-fold and 15-fold, respectively, indicating the recruitment of mitochondria-rich brown adipocyte-like cells. Absence of functional BAT leads to remodeling of white adipose tissue, which may significantly contribute to adaptive thermogenesis during cold acclimation.


Assuntos
Tecido Adiposo Marrom/metabolismo , Temperatura Baixa , Metabolismo Energético , Canais Iônicos/deficiência , Proteínas Mitocondriais/deficiência , Gordura Subcutânea/metabolismo , Termogênese , Sensação Térmica , Aclimatação , Animais , Proteínas Reguladoras de Apoptose/metabolismo , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Feminino , Canais Iônicos/genética , Metabolismo dos Lipídeos , Masculino , Potencial da Membrana Mitocondrial , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mitocôndrias Musculares/metabolismo , Proteínas Mitocondriais/genética , Músculo Esquelético/metabolismo , Miocárdio/metabolismo , Cadeias Pesadas de Miosina/metabolismo , Oxirredução , Condutividade Térmica , Fatores de Tempo , Proteína Desacopladora 1
12.
Nanoscale ; 10(38): 18153-18160, 2018 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-30132489

RESUMO

The magnetic ordering and bistability of one-dimensional chains of endofullerene Dy2ScN@C80 single-molecule magnets (SMMs) packed inside single-walled carbon nanotubes (SWCNTs) have been studied using high-resolution transmission electron microscopy (HRTEM), X-ray magnetic circular dichroism (XMCD), and ab initio calculations. X-ray absorption measurements reveal that the orientation of the encapsulated endofullerenes differs from the isotropic distribution in the bulk sample, indicating a partial ordering of the endofullerenes inside the SWCNTs. The effect of the one-dimensional packing was further investigated by ab initio calculations, demonstrating that for specific tube diameters, the encapsulation is leading to energetically preferential orientations of the endohedral clusters. Additionally, element-specific magnetization curves reveal a decreased magnetic bistability of the encapsulated Dy2ScN@C80 SMMs compared to the bulk analog.

13.
Front Physiol ; 8: 520, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28824441

RESUMO

Key Points Rectal probing is subject to procedural bias. This method is suitable for first-line phenotyping, provided probe depth and measurement duration are standardized. It is also useful for detecting individuals with out-of-range body temperatures (during hypothermia, torpor).The colonic temperature attained by inserting the probe >2 cm deep is a measure of deep (core) body temperature.IR imaging of the skin is useful for detecting heat leaks and autonomous thermoregulatory alterations, but it does not measure body temperature.Temperature of the hairy or shaved skin covering the inter-scapular brown adipose tissue can be used as a measure of BAT thermogenesis. However, obtaining such measurements of sufficient quality is very difficult, and interpreting them can be tricky. Temperature differences between the inter-scapular and lumbar areas can be a better measure of the thermogenic activity of inter-scapular brown adipose tissue.Implanted probes for precise determination of BAT temperature (changes) should be fixed close to the Sulzer's vein. For measurement of BAT thermogenesis, core body temperature and BAT temperature should be recorded simultaneously.Tail temperature is suitable to compare the presence or absence of vasoconstriction or vasodilation.Continuous, longitudinal monitoring of core body temperature is preferred over single probing, as the readings are taken in a non-invasive, physiological context.Combining core body temperature measurements with metabolic rate measurements yields insights into the interplay between heat production and heat loss (thermal conductance), potentially revealing novel thermoregulatory phenotypes. Endothermic organisms rely on tightly balanced energy budgets to maintain a regulated body temperature and body mass. Metabolic phenotyping of mice, therefore, often includes the recording of body temperature. Thermometry in mice is conducted at various sites, using various devices and measurement practices, ranging from single-time probing to continuous temperature imaging. Whilst there is broad agreement that body temperature data is of value, procedural considerations of body temperature measurements in the context of metabolic phenotyping are missing. Here, we provide an overview of the various methods currently available for gathering body temperature data from mice. We explore the scope and limitations of thermometry in mice, with the hope of assisting researchers in the selection of appropriate approaches, and conditions, for comprehensive mouse phenotypic analyses.

14.
Nat Commun ; 8(1): 1725, 2017 11 23.
Artigo em Inglês | MEDLINE | ID: mdl-29170369

RESUMO

The co-chaperone FKBP5 is a stress-responsive protein-regulating stress reactivity, and its genetic variants are associated with T2D related traits and other stress-related disorders. Here we show that FKBP51 plays a role in energy and glucose homeostasis. Fkbp5 knockout (51KO) mice are protected from high-fat diet-induced weight gain, show improved glucose tolerance and increased insulin signaling in skeletal muscle. Chronic treatment with a novel FKBP51 antagonist, SAFit2, recapitulates the effects of FKBP51 deletion on both body weight regulation and glucose tolerance. Using shorter SAFit2 treatment, we show that glucose tolerance improvement precedes the reduction in body weight. Mechanistically, we identify a novel association between FKBP51 and AS160, a substrate of AKT2 that is involved in glucose uptake. FKBP51 antagonism increases the phosphorylation of AS160, increases glucose transporter 4 expression at the plasma membrane, and ultimately enhances glucose uptake in skeletal myotubes. We propose FKBP51 as a mediator between stress and T2D development, and potential target for therapeutic approaches.


Assuntos
Proteínas Ativadoras de GTPase/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas de Ligação a Tacrolimo/metabolismo , Animais , Transporte Biológico Ativo , Dieta Hiperlipídica , Glucose/metabolismo , Transportador de Glucose Tipo 4/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Modelos Biológicos , Fibras Musculares Esqueléticas/metabolismo , Fosforilação , Transdução de Sinais , Estresse Fisiológico , Proteínas de Ligação a Tacrolimo/deficiência , Proteínas de Ligação a Tacrolimo/genética , Aumento de Peso
15.
Nat Commun ; 7: 10782, 2016 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-26923837

RESUMO

Hypothalamic leptin signalling has a key role in food intake and energy-balance control and is often impaired in obese individuals. Here we identify histone deacetylase 5 (HDAC5) as a regulator of leptin signalling and organismal energy balance. Global HDAC5 KO mice have increased food intake and greater diet-induced obesity when fed high-fat diet. Pharmacological and genetic inhibition of HDAC5 activity in the mediobasal hypothalamus increases food intake and modulates pathways implicated in leptin signalling. We show HDAC5 directly regulates STAT3 localization and transcriptional activity via reciprocal STAT3 deacetylation at Lys685 and phosphorylation at Tyr705. In vivo, leptin sensitivity is substantially impaired in HDAC5 loss-of-function mice. Hypothalamic HDAC5 overexpression improves leptin action and partially protects against HFD-induced leptin resistance and obesity. Overall, our data suggest that hypothalamic HDAC5 activity is a regulator of leptin signalling that adapts food intake and body weight to our dietary environment.


Assuntos
Hipotálamo/metabolismo , Leptina/metabolismo , Animais , Glicemia , Linhagem Celular , Regulação da Expressão Gênica , Técnicas de Silenciamento de Genes , Teste de Tolerância a Glucose , Histona Desacetilases/genética , Histona Desacetilases/metabolismo , Infusões Intraventriculares , Resistência à Insulina , Microdissecção e Captura a Laser , Leptina/genética , Masculino , Hormônios Estimuladores de Melanócitos/farmacologia , Camundongos , Camundongos Endogâmicos , Camundongos Knockout , Neurônios/fisiologia , Ratos , Ratos Wistar
16.
Curr Protoc Mouse Biol ; 5(3): 205-222, 2015 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-26331756

RESUMO

Current comprehensive mouse metabolic phenotyping involves studying energy balance in cohorts of mice via indirect calorimetry, which determines heat release from changes in respiratory air composition. Here, we describe the measurement of daily energy expenditure (DEE) and basal metabolic rate (BMR) in mice. These well-defined metabolic descriptors serve as meaningful first-line read-outs for metabolic phenotyping and should be reported when exploring energy expenditure in mice. For further guidance, the issue of appropriate sample sizes and the frequency of sampling of metabolic measurements is also discussed.


Assuntos
Calorimetria Indireta/métodos , Metabolismo Energético , Camundongos/metabolismo , Ração Animal/análise , Animais , Metabolismo Basal , Calorimetria Indireta/instrumentação
17.
Mol Metab ; 4(7): 537-42, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26137441

RESUMO

OBJECTIVE: Circulating fibroblast growth factor 21 (FGF21) is an important auto- and endocrine player with beneficial metabolic effects on obesity and diabetes. In humans, thermogenic brown adipose tissue (BAT) was recently suggested as a source of FGF21 secretion during cold exposure. Here, we aim to clarify the role of UCP1 and ambient temperature in the regulation of FGF21 in mice. METHODS: Wildtype (WT) and UCP1-knockout (UCP1 KO) mice, the latter being devoid of BAT-derived non-shivering thermogenesis, were exposed to different housing temperatures. Plasma metabolites and FGF21 levels were determined, gene expression was analyzed by qPCR, and tissue histology was performed with adipose tissue. RESULTS: At thermoneutrality, FGF21 gene expression and serum levels were not different between WT and UCP1 KO mice. Cold exposure led to highly increased FGF21 serum levels in UCP1 KO mice, which were reflected in increased FGF21 gene expression in adipose tissues but not in liver and skeletal muscle. Ex vivo secretion assays revealed FGF21 release only from BAT, progressively increasing with decreasing ambient temperatures. In association with increased FGF21 serum levels in the UCP1 KO mouse, typical FGF21-related serum metabolites and inguinal white adipose tissue morphology and thermogenic gene expression were altered. CONCLUSIONS: Here we show that the genetic ablation of UCP1 increases FGF21 gene expression in adipose tissue. The removal of adaptive nonshivering thermogenesis renders BAT a significant source of endogenous FGF21 under thermal stress. Thus, the thermogenic competence of BAT is not a requirement for FGF21 secretion. Notably, high endogenous FGF21 levels in UCP1-deficient models and subjects may confound pharmacological FGF21 treatments.

18.
EMBO Mol Med ; 7(3): 288-98, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25652173

RESUMO

We assessed the efficacy of simultaneous agonism at the glucagon-like peptide-1 receptor (GLP-1R) and the melanocortin-4 receptor (MC4R) for the treatment of obesity and diabetes in rodents. Diet-induced obese (DIO) mice were chronically treated with either the long-acting GLP-1R agonist liraglutide, the MC4R agonist RM-493 or a combination of RM-493 and liraglutide. Co-treatment of DIO mice with RM-493 and liraglutide improves body weight loss and enhances glycemic control and cholesterol metabolism beyond what can be achieved with either mono-therapy. The superior metabolic efficacy of this combination therapy is attributed to the anorectic and glycemic actions of both drugs, along with the ability of RM-493 to increase energy expenditure. Interestingly, compared to mice treated with liraglutide alone, hypothalamic Glp-1r expression was higher in mice treated with the combination therapy after both acute and chronic treatment. Further, RM-493 enhanced hypothalamic Mc4r expression. Hence, co-dosing with MC4R and GLP-1R agonists increases expression of each receptor, indicative of minimized receptor desensitization. Together, these findings suggest potential opportunities for employing combination treatments that comprise parallel MC4R and GLP-1R agonism for the treatment of obesity and diabetes.


Assuntos
Diabetes Mellitus/tratamento farmacológico , Peptídeo 1 Semelhante ao Glucagon/análogos & derivados , Hipoglicemiantes/uso terapêutico , Obesidade/tratamento farmacológico , Receptor Tipo 4 de Melanocortina/agonistas , Receptores de Glucagon/agonistas , alfa-MSH/análogos & derivados , Animais , Sinergismo Farmacológico , Quimioterapia Combinada , Peptídeo 1 Semelhante ao Glucagon/farmacologia , Peptídeo 1 Semelhante ao Glucagon/uso terapêutico , Receptor do Peptídeo Semelhante ao Glucagon 1 , Hipoglicemiantes/farmacologia , Liraglutida , Camundongos Obesos , Resultado do Tratamento , alfa-MSH/farmacologia , alfa-MSH/uso terapêutico
19.
Endocrinology ; 145(5): 2531-41, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-14726450

RESUMO

The SMA1-mouse is a novel ethyl-nitroso-urea (ENU)-induced mouse mutant that carries an a-->g missense mutation in exon 5 of the GH gene, which translates to a D167G amino acid exchange in the mature protein. Mice carrying the mutation are characterized by dwarfism, predominantly due to the reduction (sma1/+) or absence (sma1/sma1) of the GH-mediated peripubertal growth spurt, with sma1/+ mice displaying a less pronounced phenotype. All genotypes are viable and fertile, and the mode of inheritance is in accordance with a semidominant Mendelian trait. Adult SMA1 mice accumulate excessive amounts of sc and visceral fat in the presence of elevated plasma ghrelin levels, possibly reflecting altered energy partitioning. Our results suggest impaired storage and/or secretion of pituitary GH in mutants, resulting in reduced pituitary GH and reduced GH-stimulated IGF-1 expression. Generation and identification of the SMA1 mouse exemplifies the power of the combination of random mouse mutagenesis with a highly detailed phenotype-analysis as a successful strategy for the detection and analysis of novel gene-function relationships.


Assuntos
Nanismo/genética , Hormônio do Crescimento/genética , Mutação de Sentido Incorreto , Obesidade/genética , Hormônios Peptídicos/sangue , Tecido Adiposo , Sequência de Aminoácidos , Animais , Composição Corporal/genética , Peso Corporal/genética , Éxons , Feminino , Fertilidade , Ligação Genética , Genótipo , Grelina , Hormônio do Crescimento/análise , Hormônio do Crescimento/química , Humanos , Fator de Crescimento Insulin-Like I/análise , Fator de Crescimento Insulin-Like I/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C3H , Dados de Sequência Molecular , Fenótipo , Hipófise/química , Alinhamento de Sequência
20.
Free Radic Biol Med ; 77: 210-6, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25224037

RESUMO

Mitochondrial uncoupling reduces reactive oxygen species (ROS) production and appears to be important for cellular signaling/protection, making it a focus for the treatment of metabolic and age-related diseases. Whereas the physiological role of uncoupling protein 1 (UCP1) of brown adipose tissue is established for thermogenesis, the function of UCP1 in the reduction of ROS in cold-exposed animals is currently under debate. Here, we investigated the role of UCP1 in mitochondrial ROS handling in the Lesser hedgehog tenrec (Echinops telfairi), a unique protoendothermic Malagasy mammal with recently identified brown adipose tissue (BAT). We show that the reduction of ROS by UCP1 activity also occurs in BAT mitochondria of the tenrec, suggesting that the antioxidative role of UCP1 is an ancient mammalian trait. Our analysis shows that the quantity of UCP1 displays strong control over mitochondrial hydrogen peroxide release, whereas other factors, such as mild cold, nonshivering thermogenesis, oxidative capacity, and mitochondrial respiration, do not correlate. Furthermore, hydrogen peroxide release from recoupled BAT mitochondria was positively associated with mitochondrial membrane potential. These findings led to a model of UCP1 controlling mitochondrial ROS release and, presumably, being controlled by high membrane potential, as proposed in the canonical model of "mild uncoupling". Our study further promotes a conserved role for UCP1 in the prevention of oxidative stress, which was presumably established during evolution before UCP1 was physiologically integrated into nonshivering thermogenesis.


Assuntos
Eulipotyphla/metabolismo , Canais Iônicos/fisiologia , Mitocôndrias/metabolismo , Proteínas Mitocondriais/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Aclimatação , Tecido Adiposo Marrom/metabolismo , Animais , Evolução Biológica , Potencial da Membrana Mitocondrial , Estresse Oxidativo , Proteína Desacopladora 1
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