RESUMO
Autophagy is a metabolic process that is important in fibrogenesis, in which cellular components are degraded by lysosomal machinery. Transforming growth factor ß1 (TGFß1) is a potent fibrogenic cytokine involved in liver fibrosis; however, it remains elusive whether autophagy is regulated by TGFß1 in this process. In the present study, the function of TGFß1mediated autophagy in the proliferation and apoptosis of hepatic stellate cells (HSCs) was investigated. A rat HSC cell line (HSCT6) was incubated with or without TGFß1 followed by bafilomycin A1, and microtubule-associated proteins 1A/1B light chain 3 (LC3) small interfering (si)RNA was used to inhibit autophagy in order to assess the association between TGFß1 and autophagy. HSCT6 cell transient transfection was accomplished with a pLVXAcGFPN1rLC3Bencoding plasmid. An MTS assay and flow cytometry were utilized to detect proliferation and apoptosis of HSCT6 cells. Quantitative polymerase chain reaction, immunoï¬uorescence and western blot analysis were used to detect the presence of activation markers. Proliferation was increased and apoptosis was reduced in HSCT6 cells treated with TGFß1 compared with cells subjected to serum deprivation. However, when HSCT6 cells were treated with bafilomycin A1 and LC3 siRNA, increased apoptosis and reduced proliferation were observed. In addition, protein and mRNA expression levels of the autophagy marker LC3 were significantly increased. GFPLC3 punctate markings were more prolific following TGFß1 treatment of HSCT6 cells, indicating that TGFß1 may rescue HSCT6 cells from serum deprivation and reduce apoptosis via autophagy induction. The present study elucidated the possible functions of TGFß1mediated autophagy in the pathological process of liver fibrosis.
Assuntos
Apoptose , Autofagia , Células Estreladas do Fígado/metabolismo , Fator de Crescimento Transformador beta1/farmacologia , Animais , Caspase 3/genética , Caspase 3/metabolismo , Linhagem Celular , Proliferação de Células/fisiologia , Inibidores Enzimáticos/farmacologia , Cirrose Hepática/metabolismo , Macrolídeos/farmacologia , Proteínas Associadas aos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Ratos , TransfecçãoRESUMO
Nerve growth factor (NGF) regulates the proliferation, differentiation and survival of cells and is also involved in the wound healing and tissue remodeling processes. The biological effects of NGF are dependent upon receptor signal-mediating functions, which differ between cells. This study attempted to investigate the hepatoprotective effect and possible mechanism of ß-NGF on D-galactosamine (D-GalN)-injured human liver L-02 cell lines. We demonstrated that L-02 cells expressed the neurotrophin receptors tyrosine kinase-A nerve growth factor receptor (TrkA NGFR) and p75 pan-neurotrophin receptor (p75NTR). Recombinant human ß-NGF markedly reduced cell injury and promoted the proliferation of L-02 cells damaged by D-GalN. However, this proliferation effect was blocked by the anti-TrkA NGFR antibody. Lactate dehydrogenase (LDH) and malondialdehyde (MDA) were released at reduced levels in the L-02 cell culture supernatant pretreated with ß-NGF. Furthermore, the albumin (ALB) content in the cell medium and intracellular glutathione (GSH) levels were markedly augmented, and the permeability of the mitochondrial membrane of the L-02 cells was improved by ß-NGF. Our results suggested that exogenous ß-NGF protects L-02 cells from D-GalN-induced injury through the NGF/TrkA NGFR signaling pathway.