RESUMO
Docosahexaenoic acid (DHA) increases lipolysis and decreases lipogenesis through several pathways. DHA also enhances the expression of serum amyloid A protein (SAA), a possible lipid metabolism related gene. The question of whether DHA regulates the expression of SAA to affect lipid metabolism and increase lipolysis needs to be demonstrated in human adipocytes. We designed experiments to determine the role of SAA in regulating lipid metabolism in HepG2 cells using microarray technology. In human hepatocytes, recombinant human SAA1 (hSAA1) inhibited the expression of genes related to lipogenesis and promoted the expression of those involved in lipolysis. When human breast adipocytes were treated with hSAA1 or DHA in vitro, the expression of peroxisome proliferator-activated receptor gamma and other lipogenic genes was decreased, whereas the expression of several lipolytic genes was increased. Glycerol release was increased by both SAA and DHA treatments, suggesting that they increased lipolytic activity in human adipocytes. The expression of perilipin, a lipid droplet-protective protein, was decreased, and hormone-sensitive lipase was increased by both of hSAA1 and DHA treatment. We speculate that the mechanism of lipolysis by DHA or SAA is at least partially the result of increased expression of hormone-sensitive lipase and decreased expression of perilipin. Whereas DHA treatment increased expression of hSAA1 in human adipocytes, the DHA-mediated reduction in expression of lipogenesis genes and enhancement of lipolysis may be through the activity of hSAA1. These results may be useful in developing new approaches to reduce body fat deposition.
Assuntos
Ácidos Docosa-Hexaenoicos/administração & dosagem , Lipólise , Fosfoproteínas/metabolismo , Proteína Amiloide A Sérica/fisiologia , Adipócitos Brancos/enzimologia , Adipócitos Brancos/metabolismo , Adipogenia , Tecido Adiposo Branco/citologia , Tecido Adiposo Branco/enzimologia , Tecido Adiposo Branco/metabolismo , Proteínas de Transporte , Células Cultivadas , Regulação para Baixo , Feminino , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Células Hep G2 , Humanos , Interleucina-6/genética , Interleucina-6/metabolismo , Lipogênese , Análise de Sequência com Séries de Oligonucleotídeos , Perilipina-1 , Fosfoproteínas/genética , Proteínas Recombinantes , Proteína Amiloide A Sérica/genética , Esterol Esterase/genética , Esterol Esterase/metabolismo , Células Estromais/metabolismoRESUMO
Apoptosis plays an important role in pathogenesis of many viral infections. Infection of chicken with avian reovirus S1133 causes tissue injury related to virus-induced apoptosis. To determine whether avian reovirus (ARV) induced apoptosis in chicken tissues, six 3-week-old specific pathogen free White Leghorn chicks were inoculated with ARV S1133. Tissues were dual-labelled for the simultaneous detection of viral antigen containing and apoptotic cells. DNA laddering was detected in ARV-infected but not mock-infected chicken tissues. Dual-labelling assay revealed that the majority of antigen-expressing cells were not apoptotic. Surprisingly, some apoptotic but non-antigen-expressing cells were frequently located in the vicinity of antigen-expressing cells. Syncytium formation in ARV-infected chicken tissues undergoing apoptosis was apparent, suggesting a correlation between virus replication and apoptosis in chicken tissues.
