RESUMO
Lysophosphatidylcholine (LPC), the active metabolite of palmitate, triggers hepatocyte death by activating endoplasmic reticulum stress and JNK signalling-mediated lipoapoptosis. However, LPC-induced cytotoxicity in hepatocytes is not well understood. Here, we found for the first time that LPC-induced cell rounding occurred prior to apoptosis. LPC-induced rounding of cells reduced both cell-extracellular matrix (ECM) adhesion and cell-cell junctions, which promoted detachment-induced apoptosis (defined as anoikis) in hepatocytes. Further study revealed that LPC altered cellular morphology and cell adhesion by inhibiting integrin and cadherin signalling-mediated microfilament polymerization. We also found that ECM supplementation and microfilament cytoskeletal stabilization inhibited LPC-induced hepatocyte death by attenuating anoikis. Our data indicate a novel cytotoxic process and signalling pathway induced by LPC.
Assuntos
Anoikis/efeitos dos fármacos , Caderinas/genética , Adesão Celular/efeitos dos fármacos , Integrinas/genética , Junções Intercelulares/efeitos dos fármacos , Lisofosfatidilcolinas/farmacologia , Citoesqueleto de Actina/efeitos dos fármacos , Citoesqueleto de Actina/metabolismo , Citoesqueleto de Actina/ultraestrutura , Anoikis/genética , Proteínas Reguladoras de Apoptose/genética , Proteínas Reguladoras de Apoptose/metabolismo , Caderinas/metabolismo , Caspase 8/genética , Caspase 8/metabolismo , Linhagem Celular Tumoral , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Estresse do Retículo Endoplasmático/genética , Matriz Extracelular/efeitos dos fármacos , Matriz Extracelular/metabolismo , Matriz Extracelular/ultraestrutura , Regulação da Expressão Gênica , Células Hep G2 , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Hepatócitos/ultraestrutura , Humanos , Integrinas/metabolismo , Junções Intercelulares/metabolismo , Junções Intercelulares/ultraestrutura , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Transdução de Sinais , Vinculina/genética , Vinculina/metabolismoRESUMO
OBJECTIVE: In this study, we aim to explore the role of bone marrow macrophage-derived exosomes in hepatic insulin resistance, investigate the substance in exosomes that regulates hepatic insulin signalling pathways, reveal the specific molecular mechanisms involved in hepatic insulin resistance and further explore the role of exosomes in type 2 diabetes. MATERIALS AND METHODS: High-fat diet (HFD)-fed mice were used as obesity-induced hepatic insulin resistance model, exosomes were isolated from BMMs which were extracted from HFD-fed mice by ultracentrifugation. Exosomes were analysed the spectral changes of microRNA expression using a microRNA array. The activation of the insulin signalling pathway and the level of glycogenesis were examined in hepatocytes after transfected with miR-143-5p mimics. Luciferase assay and western blot were used to assess the target of miR-143-5p. RESULTS: BMMs from HFD-fed mice were polarized towards M1, and miR-143-5p was significantly upregulated in exosomes of BMMs from HFD-fed mice. Overexpression of miR-143-5p in Hep1-6 cells led to decreased phosphorylation of AKT and GSK and glycogen synthesis. Dual-luciferase reporter assay and western blot demonstrated that mitogen-activated protein kinase phosphatase-5 (Mkp5, also known as Dusp10) was the target gene of miR-143-5p. Moreover, the overexpression of MKP5 could rescue the insulin resistance induced by transfection miR-143-5p mimics in Hep1-6. CONCLUSION: Bone marrow macrophage-derived exosomal miR-143-5p induces insulin resistance in hepatocytes through repressing MKP5.