RESUMO
During menadione stress, trehalose was necessary intracellularly, but under H2O2, the sugar was required on the outside of the plasma membrane. The mechanism of protection involves minimizing the oxidative damage caused to both proteins and lipids, which would require the presence of trehalose on both sides of the lipid bilayer.
Assuntos
Proteínas de Transporte de Monossacarídeos/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Proteínas de Saccharomyces cerevisiae/fisiologia , Saccharomyces cerevisiae/metabolismo , Simportadores/fisiologia , Trealose/fisiologia , Glucosiltransferases/genética , Peróxido de Hidrogênio/farmacologia , Peroxidação de Lipídeos , Proteínas de Transporte de Monossacarídeos/genética , Mutação , Oxidantes/farmacologia , Estresse Oxidativo , Carbonilação Proteica , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Simportadores/genética , Trealose/farmacologia , Vitamina K 3/farmacologiaRESUMO
The mechanisms involved in D-glucose and amino acid transport in the intestine of birds are still not clear. In chickens, D-glucose and amino acid absorption occurs via carrier-mediated transport, but in wild birds a passive paracellular mechanism seems to be the predominant pathway. The purpose of this work was to determine the existence of carrier-mediated sodium cotransport of D-glucose and L-alanine in the small intestine of Japanese quail (Coturnix coturnix), a granivorous bird. Intestinal transport was determined by changes in the short-circuit current (Isc), proportional to ion transmembrane flux, in the middle segment of the intestine of Japanese quail with a Ussing chamber. D-Glucose produced an increase of the Isc, and this effect was reverted by phloridzin, indicating the presence of a D-glucose transport mediated by the sodium/glucose cotranspoter 1. Addition of L-alanine also produced an increase of the Isc. We concluded that there is carrier-mediated cotransport of D-glucose and L-alanine with sodium in the small intestine of the Japanese quail.
Assuntos
Alanina/metabolismo , Coturnix/metabolismo , Glucose/metabolismo , Animais , Transporte Biológico/efeitos dos fármacos , Condutividade Elétrica , Impedância Elétrica , Glucose/farmacologia , Absorção Intestinal/efeitos dos fármacos , Absorção Intestinal/fisiologia , Intestino Delgado/fisiologia , Masculino , Proteínas de Transporte de Monossacarídeos/efeitos dos fármacos , Proteínas de Transporte de Monossacarídeos/fisiologia , Florizina/farmacologiaRESUMO
Trypanosoma cruzi must invade mammalian host cells to replicate and complete its life cycle. Almost all nucleated mammalian cells can be invaded by the parasite following a receptor-ligand recognition as an early prerequisite. In this work, we describe a 67-kDa lectin-like glycoprotein that binds to desialylated human erythrocyte membranes in a galactose-dependent way. This protein is present on the parasite surface in both infective and non-infective stages of T. cruzi. More interestingly, we demonstrate by lectin-immuno-histochemistry assays that the 67kDa protein is involved in the recognition of host-cell receptors in mouse cardiac tissue and human cardiac aortic endothelium and mammary artery tissue. Moreover, antibodies against the 67kDa glycoprotein inhibit in vitro host-cell invasion by 63%. These data suggest that the 67kDa glycoprotein in vivo is needed for host-cell invasion by T. cruzi.
Assuntos
Proteínas de Ligação ao Cálcio , Membrana Eritrocítica/metabolismo , Proteínas de Helminto/isolamento & purificação , Proteínas de Transporte de Monossacarídeos/isolamento & purificação , Proteínas Periplásmicas de Ligação , Trypanosoma cruzi/fisiologia , Animais , Western Blotting , Cromatografia de Afinidade , Eletroforese em Gel de Poliacrilamida , Endotélio Vascular/metabolismo , Endotélio Vascular/parasitologia , Membrana Eritrocítica/parasitologia , Imunofluorescência , Galactose/metabolismo , Coração/parasitologia , Proteínas de Helminto/imunologia , Proteínas de Helminto/fisiologia , Humanos , Soros Imunes/imunologia , Imuno-Histoquímica , Lectinas , Camundongos , Camundongos Endogâmicos BALB C , Proteínas de Transporte de Monossacarídeos/imunologia , Proteínas de Transporte de Monossacarídeos/fisiologia , Coelhos , Trypanosoma cruzi/químicaRESUMO
GLUT4 protein expression in white adipose tissue (WAT) and skeletal muscle (SM) was investigated in 2-month-old, 12-month-old spontaneously obese or 12-month-old calorie-restricted lean Wistar rats, by considering different parameters of analysis, such as tissue and body weight, and total protein yield of the tissue. In WAT, an approximately 70% decrease was observed in plasma membrane and microsomal GLUT4 protein, expressed as microg protein or g tissue, in both 12-month-old obese and 12-month-old lean rats compared to 2-month-old rats. However, when plasma membrane and microsomal GLUT4 tissue contents were expressed as g body weight, they were the same. In SM, GLUT4 protein content, expressed as microg protein, was similar in 2-month-old and 12-month-old obese rats, whereas it was reduced in 12-month-old obese rats, when expressed as g tissue or g body weight, which may play an important role in insulin resistance. Weight loss did not change the SM GLUT4 content. These results show that altered insulin sensitivity is accompanied by modulation of GLUT4 protein expression. However, the true role of WAT and SM GLUT4 contents in whole-body or tissue insulin sensitivity should be determined considering not only GLUT4 protein expression, but also the strong morphostructural changes in these tissues, which require different types of data analysis.