RESUMO
INTRODUCTION: Uncoupling protein 2 (UCP2) reduces production of reactive oxygen species (ROS) by mitochondria. ROS overproduction is one of the major contributors to the pathogenesis of chronic diabetic complications, such as diabetic kidney disease (DKD). Thus, deleterious polymorphisms in the UCP2 gene are candidate risk factors for DKD. In this study, we investigated whether UCP2 -866G/A, Ala55Val and Ins/Del polymorphisms were associated with DKD in patients with type 2 diabetes mellitus (T2DM), and whether they had an effect on UCP2 gene expression in human kidney tissue biopsies. MATERIALS AND METHODS: In a case-control study, frequencies of the UCP2 -866G/A, Ala55Val and Ins/Del polymorphisms as well as frequencies of the haplotypes constituted by them were analyzed in 287 T2DM patients with DKD and 281 T2DM patients without this complication. In a cross-sectional study, UCP2 gene expression was evaluated in 42 kidney biopsy samples stratified according to the presence of the UCP2 mutated -866A/55Val/Ins haplotype. RESULTS: In the T2DM group, multivariate logistic regression analysis showed that the -866A/55Val/Ins haplotype was an independent risk factor for DKD (OR = 2.136, 95% CI 1.036-4.404), although neither genotype nor allele frequencies of the individual polymorphisms differed between case and control groups. Interestingly, T2DM patients carrying the mutated haplotype showed decreased estimated glomerular filtration rate (eGFR) when compared to subjects with the reference haplotype (adjusted P= 0.035). In kidney biopsy samples, UCP2 expression was significantly decreased in UCP2 mutated haplotype carriers when compared to kidneys from patients with the reference haplotype (0.32 ± 1.20 vs. 1.85 ± 1.16 n fold change; adjusted P< 0.000001). DISCUSSION: Data reported here suggest that the UCP2 -866A/55Val/Ins haplotype is associated with an increased risk for DKD and with a lower eGFR in T2DM patients. Furthermore, this mutated haplotype was associated with decreased UCP2 gene expression in human kidneys.
Assuntos
Diabetes Mellitus Tipo 2 , Nefropatias Diabéticas , Regulação da Expressão Gênica , Taxa de Filtração Glomerular/genética , Canais Iônicos , Rim/metabolismo , Proteínas Mitocondriais , Mutação de Sentido Incorreto , Adulto , Substituição de Aminoácidos , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patologia , Nefropatias Diabéticas/genética , Nefropatias Diabéticas/metabolismo , Nefropatias Diabéticas/patologia , Feminino , Humanos , Canais Iônicos/biossíntese , Canais Iônicos/genética , Rim/patologia , Masculino , Proteínas Mitocondriais/biossíntese , Proteínas Mitocondriais/genética , Proteína Desacopladora 2RESUMO
The serotonergic system plays a crucial role in the energy balance regulation. Energy balance is mediated by food intake and caloric expenditure. Thus, the present study investigated the mechanisms that might be associated with fluoxetine treatment-induced weight reduction. Wistar male rat pups received daily injections with subcutaneous fluoxetine (Fx-group) or vehicle solution (Ct-group) from day 1 until 21 days of age. Several analyses were conducted to verify the involvement of mitochondria in weight reduction. We found that body weight in the Fx-group was lower compared to control. In association to lower fat mass in the Fx-group (25%). Neither neonatal caloric intake nor food intake reveals significant differences. Evaluating caloric expenditure (locomotor activity and temperature after stimulus), we did not observe differences in locomotor activity. However, we observed that the Fx group had a higher capacity to maintain body temperature in a cold environment compared with the Ct-group. Since brown adipose tissue-(BAT) is specialized for heat production and the rate of heat production is related to mitochondrial function, we found that Fx-treatment increases respiration by 36%, although after addition of GDP respiration returned to Ct-levels. Examining ROS production we observe that Fx-group produced less ROS than control group. Evaluating uncoupling protein (UCP) expression we found that Fx-treatment increases the expression by 23%. Taken together, our results suggest that modulation of serotonin system results in positive modulation of UCP and mitochondrial bioenergetics in brown fat tissue.
Assuntos
Tecido Adiposo Marrom/metabolismo , Tecido Adiposo Branco/metabolismo , Metabolismo Energético/efeitos dos fármacos , Fluoxetina/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Canais Iônicos/biossíntese , Proteínas Mitocondriais/biossíntese , Animais , Masculino , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Proteína Desacopladora 1RESUMO
Mitochondrial inner membrane uncoupling proteins (UCP) dissipate the proton electrochemical gradient established by the respiratory chain, thus affecting the yield of ATP synthesis. UCP overexpression in plants has been correlated with oxidative stress tolerance, improved photosynthetic efficiency and increased mitochondrial biogenesis. This study reports the main transcriptomic responses associated with the overexpression of an UCP (AtUCP1) in tobacco seedlings. Compared to wild-type (WT), AtUCP1 transgenic seedlings showed unaltered ATP levels and higher accumulation of serine. By using RNA-sequencing, a total of 816 differentially expressed genes between the investigated overexpressor lines and the untransformed WT control were identified. Among them, 239 were up-regulated and 577 were down-regulated. As a general response to AtUCP1 overexpression, noticeable changes in the expression of genes involved in energy metabolism and redox homeostasis were detected. A substantial set of differentially expressed genes code for products targeted to the chloroplast and mainly involved in photosynthesis. The overall results demonstrate that the alterations in mitochondrial function provoked by AtUCP1 overexpression require important transcriptomic adjustments to maintain cell homeostasis. Moreover, the occurrence of an important cross-talk between chloroplast and mitochondria, which culminates in the transcriptional regulation of several genes involved in different pathways, was evidenced.
Assuntos
Regulação da Expressão Gênica de Plantas , Canais Iônicos/biossíntese , Proteínas Mitocondriais/biossíntese , Nicotiana/genética , Transcriptoma , Trifosfato de Adenosina/metabolismo , Antioxidantes/metabolismo , Cloroplastos/metabolismo , Perfilação da Expressão Gênica , Homeostase , Mitocôndrias/metabolismo , Oxirredução , Fosforilação Oxidativa , Estresse Oxidativo , Fotossíntese , Plantas Geneticamente Modificadas/genética , RNA/genética , Plântula , Análise de Sequência de RNA , Proteína Desacopladora 1RESUMO
T leukemogenesis is a multistep process, where the genetic errors during T cell maturation cause the healthy progenitor to convert into the leukemic precursor that lost its ability to differentiate but possesses high potential for proliferation, self-renewal, and migration. A new misdirecting "leukemogenic" signaling network appears, composed by three types of participants which are encoded by (1) genes implicated in determined stages of T cell development but deregulated by translocations or mutations, (2) genes which normally do not participate in T cell development but are upregulated, and (3) nondifferentially expressed genes which become highly interconnected with genes expressed differentially. It appears that each of three groups may contain genes coding ion channels. In T cells, ion channels are implicated in regulation of cell cycle progression, differentiation, activation, migration, and cell death. In the present review we are going to reveal a relationship between different genetic defects, which drive the T cell neoplasias, with calcium signaling and ion channels. We suggest that changes in regulation of various ion channels in different types of the T leukemias may provide the intracellular ion microenvironment favorable to maintain self-renewal capacity, arrest differentiation, induce proliferation, and enhance motility.
Assuntos
Carcinogênese/genética , Diferenciação Celular/genética , Canais Iônicos/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Proliferação de Células/genética , Regulação Leucêmica da Expressão Gênica , Células-Tronco Hematopoéticas/patologia , Humanos , Canais Iônicos/biossíntese , Linfócitos/patologia , Leucemia-Linfoma Linfoblástico de Células T Precursoras/patologia , Transdução de Sinais/genética , Timócitos/patologia , Microambiente Tumoral/genéticaRESUMO
The altricial young of the European rabbit (Oryctolagus cuniculus) are not brooded by the mother, and although they are born into an underground nest, depend importantly on the warmth and insulation provided by littermates for their early growth and survival. Consistent with previous studies, heavier pups occupied more central, thermally advantageous positions in the litter huddle, maintained higher body temperatures, obtained more milk, were more efficient at converting it to body mass, and consequently grew faster than their lighter sibs occupying the periphery of the huddle. In the present study we measured the expression of uncoupling protein 1 (UCP-1), which is essential for the metabolism of brown adipose tissue to generate body heat in response to cold. In nine litters of domestic rabbits maintained for the first four postnatal days at temperatures below their critical thermoneutral temperature, peripheral pups showed greater expression of UCP-1 than intermediate pups, and these greater expression than central pups. This suggests that during early development littermates of the rabbit experience differing degrees of activation of the sympathetic nervous system as a consequence of exposure to different thermal environments associated with different positions in the litter huddle. Whether this is associated with long term differences in the physiological response to cold and perhaps in the manner of responding to other environmental challenges is currently under investigation.
Assuntos
Tecido Adiposo Marrom/metabolismo , Animais Recém-Nascidos/fisiologia , Temperatura Corporal/fisiologia , Comportamento Competitivo/fisiologia , Ingestão de Alimentos , Metabolismo dos Lipídeos/fisiologia , Envelhecimento/fisiologia , Envelhecimento/psicologia , Animais , Western Blotting , Peso Corporal/fisiologia , Chinchila , Interpretação Estatística de Dados , Eletroforese em Gel de Poliacrilamida , Feminino , Individualidade , Canais Iônicos/biossíntese , Masculino , Proteínas Mitocondriais/biossíntese , Gravidez , Coelhos , Comportamento de Sucção , Proteína Desacopladora 1RESUMO
Uncoupling protein 2 (UCP2) is highly expressed in the hypothalamus; however, little is known about the functions it exerts in this part of the brain. Here, we hypothesized that UCP2 protects hypothalamic cells from oxidative and pro-apoptotic damage generated by inflammatory stimuli. Intracerebroventricular injection of tumor necrosis factor alpha (TNF-alpha)-induced an increase of UCP2 expression in the hypothalamus, which was accompanied by increased expression of markers of oxidative stress and pro-apoptotic proteins. The inhibition of UCP2 expression by an antisense oligonucleotide enhanced the damaging effects of TNF-alpha. Conversely, increasing the hypothalamic expression of UCP2 by cold exposure reversed most of the effects of the cytokine. Thus, UCP2 acts as a protective factor against cellular damage induced by an inflammatory stimulus in the hypothalamus.
Assuntos
Apoptose , Hipotálamo/citologia , Hipotálamo/metabolismo , Canais Iônicos/fisiologia , Proteínas Mitocondriais/fisiologia , Animais , Células Cultivadas , Temperatura Baixa , Canais Iônicos/antagonistas & inibidores , Canais Iônicos/biossíntese , Masculino , Proteínas Mitocondriais/antagonistas & inibidores , Proteínas Mitocondriais/biossíntese , Ratos , Ratos Wistar , Fator de Necrose Tumoral alfa/farmacologia , Fator de Necrose Tumoral alfa/fisiologia , Proteína Desacopladora 2RESUMO
An immortal, cloned cell line (RCMH), obtained from human skeletal muscle was established in our laboratory and shown to express muscle specific proteins. We measured ligand binding to ion channels, ion currents using whole cell patch clamp and intracellular calcium both in cells grown in complete media and in cells grown for 4-40 days in media supplemented with hormones and nutrients (differentiating media). Markers for differentiated muscle, such as the muscle isoform of creatine kinase and the cytoskeletal proteins alpha-actinin, alpha-sarcomeric actin, myosin and titin were present in early stages. Receptors for gamma toxin from Tityus serrulatus scorpion venom, a specific modulator for voltage dependent sodium channels, were present (0.9-1.0 pmol mg-1 protein) during stage 1 (0-6 days in culture with differentiating media) and increased by 50% in stage 3 (more than 10 days in differentiating media). High and low affinity dihydropyridine receptors present in stage 1 convert into a single type of high affinity receptors in stage 3. Both intracellular calcium release and InsP3 receptors were evident in stage 1 but ryanodine receptors were expressed only in stage 3. RCMH cells showed no voltage sensitive currents in stage 1. Between 7 and 10 days in differentiating media (stage 2), an outward potassium current was observed. Small inward currents appeared only in stage 3; we identified both tetrodotoxin sensitive and tetrodotoxin resistant sodium currents as well as calcium currents. This pattern is consistent with the expression of voltage dependent calcium release before appearance of both the action potential and ryanodine receptors.