RESUMO
We studied the role of a central domain of human apolipoprotein AI (apoAI) in cholesterol mobilization and removal from cells. In order to check different protein conformations, we tested different sized and cholesterol-content reconstituted apoAI particles (rHDL). Meanwhile cholesterol-free discs were active to induce mobilization, only small cholesterol-containing rHDL were active. To test the influence of a central domain in such events, we used two apoAI variants: one, with its central Y helix pair replaced by the C-terminal domain, and the other having a lysine deleted in central region. The helix-swapping variant decrease the cholesterol pool available to acyl-CoA cholesterol acyl transferase and increase mobilization of newly synthesized cholesterol. Instead, the deletion mutant had no effect on both events. We conclude that the central domain of apoAI is involved in cholesterol cell traffic and solubilization, and that a Y-type charge distribution in polar face may be required, as well as a correct helices-polar face orientation.
Assuntos
Apolipoproteína A-I/fisiologia , Colesterol/metabolismo , Líquido Intracelular/metabolismo , Mobilização Lipídica/fisiologia , Peptídeos/fisiologia , Sequência de Aminoácidos , Substituição de Aminoácidos/genética , Animais , Apolipoproteína A-I/química , Apolipoproteína A-I/genética , Células CHO , Colesterol/química , Colesterol/deficiência , HDL-Colesterol/química , HDL-Colesterol/fisiologia , Cricetinae , Cricetulus , Humanos , Líquido Intracelular/química , Mobilização Lipídica/genética , Lisina/genética , Dados de Sequência Molecular , Peptídeos/química , Peptídeos/genética , Estrutura Secundária de Proteína/genética , Estrutura Terciária de Proteína , Solubilidade , Eletricidade EstáticaAssuntos
Humanos , Hiperlipidemias/diagnóstico , Hiperlipoproteinemias/diagnóstico , Lipoproteínas/metabolismo , Apolipoproteínas/metabolismo , Hiperlipidemias/etiologia , Hiperlipoproteinemias/etiologia , Lipoproteína(a)/metabolismo , Lipoproteínas HDL/metabolismo , Lipoproteínas LDL/metabolismo , Lipoproteínas , Mobilização Lipídica/fisiologiaRESUMO
To investigate the role of the central cholinergic system in the regulation of metabolism during exercise, we injected atropine (5 x 10(-7) mol) into the lateral cerebral ventricle of normal and adrenodemedullated (ADM) untrained rats submitted to exercise on a treadmill (15 m min(-1), 5% grade) until exhaustion. Concentrations of blood glucose, plasma free fatty acids (FFA), and lactate were measured before and every 10 min after the start of exercise for a period of 60 min. Adrenomedullectomy had no effect on the maximal capacity of exercise (MCE), but atropine administered intracerebroventricularly (i.c.v.) reduced the maximal capacity of exercise of both normal and ADM rats. In normal rats, blood concentrations of glucose and plasma free fatty acids remained essentially unchanged compared to the levels at rest, whereas in ADM rats a rapid increase in plasma glucose and plasma free fatty acids levels occurred during exercise. These data indicate that adrenomedullectomy disrupted the accuracy of the feedback mechanism that regulates the mobilization of extramuscular fuels during exercise in normal rats. In addition, ADM rats showed an increased lipid mobilization as a source of energy during exercise, which might explain the increased plasma glucose by an inhibition of muscle glucose uptake. These results suggest that central cholinergic neurons might be involved in the control of energy substrate adjustment during exercise, thereby reducing the maximal capacity of exercise. In addition, the results of this study suggest that the adrenal glands are important for an accurate feedback mechanism during exercise.
Assuntos
Medula Suprarrenal/fisiologia , Atropina/administração & dosagem , Glicemia/efeitos dos fármacos , Ácidos Graxos não Esterificados/sangue , Ácido Láctico/sangue , Condicionamento Físico Animal/fisiologia , Medula Suprarrenal/cirurgia , Adrenalectomia , Análise de Variância , Animais , Glicemia/metabolismo , Retroalimentação/efeitos dos fármacos , Retroalimentação/fisiologia , Injeções Intraventriculares , Mobilização Lipídica/fisiologia , Masculino , Ratos , Valores de ReferênciaRESUMO
Colletotrichum graminicola, a pathogen of sorghum and corn, was investigated prior and during germination as to certain aspects of acid phosphatase activity and lipid mobilization. Ungerminated conidia cytoplasm was filled with lipid deposits, which were mobilized during the germination process. Cytochemical ultrastructural examination showed that conidia vacuoles exhibit acid phosphatase activity, which is suggestive of lytic activity. Lipid bodies, stored in the ungerminated conidia cytoplasm, were internalized by vacuoles in a process analogous to microautophagy and were apparently digested inside them. The lipid bodies disappeared and vacuoles became enlarged in conidial cells during germination. Appressoria also showed acid phosphatase activity in multiple heterogeneous vesicles which were, in most cases, juxtaposed with lipid bodies. These results suggest that the vacuolar system plays an important role during C. graminicola germination and that the initial stages of lipid metabolization are taking place inside the vacuoles.
Assuntos
Fosfatase Ácida/metabolismo , Mobilização Lipídica/fisiologia , Fungos Mitospóricos/enzimologia , Fungos Mitospóricos/metabolismo , Fungos Mitospóricos/fisiologia , Fungos Mitospóricos/ultraestruturaRESUMO
In this study, metabolic changes of several adipose depots as caused by aging were investigated. Key enzyme activity of glutaminolysis, pentose-phosphate pathway and Krebs cycle were measured. The rates of lipogenesis from 3H2O, lipoprotein lipase (LPL) activity and rate of lipolysis in vitro were also determined. The results obtained indicate a reduced capacity for lipogenesis in several adipose depots by aging. The authors concluded that hypertrophy of adipose tissue reported during aging is possible due to increased LPL activity and reduced rate of lipolysis.