RESUMO
AIMS: Pro-inflammatory response of vascular smooth muscle cells (VSMCs) is triggered by endothelial damage and a causative step for thrombosis and neointimal thickening in the injured arterial vessels. Therefore, we investigate a role of cytosolic Hsp60 as a novel pro-inflammatory mediator in VSMCs. METHODS AND RESULTS: Hsp60 was detected in the cytosol of VSMCs. The selective depletion of cytosolic Hsp60 in VSMCs reduced the IκB kinase activation, repressed the induction of nuclear factor (NF)-κB-dependent survival genes (MnSOD and Bfl-1/A1), and enhanced apoptotic death in response to TNF-α. Moreover, a quantitative RNA sequencing revealed that the expression of 75 genes among the 774 TNF-α-inducible genes was significantly reduced by the depletion of cytosolic Hsp60. In particular, the expression of pro-inflammatory cytokines/chemokines, such as CCL2, CCL20, and IL-6, was regulated by the cytosolic Hsp60 in VSMCs. Finally, the depletion of cytosolic Hsp60 markedly inhibited the neointimal thickening in the balloon-injured arterial vessels by inducing apoptotic cell death and inhibiting chemokine production. CONCLUSIONS: This study provides the first evidence that cytosolic Hsp60 could be a therapeutic target for preventing VSMC hyperplasia and inflammatory response in the injured vessels.
Assuntos
Aortite/metabolismo , Chaperonina 60/metabolismo , Citosol/metabolismo , Mediadores da Inflamação/metabolismo , Proteínas Mitocondriais/metabolismo , Músculo Liso Vascular/metabolismo , Miócitos de Músculo Liso/metabolismo , Lesões do Sistema Vascular/metabolismo , Animais , Aorta/lesões , Aorta/metabolismo , Aorta/patologia , Aortite/genética , Aortite/patologia , Apoptose , Lesões das Artérias Carótidas/metabolismo , Lesões das Artérias Carótidas/patologia , Sobrevivência Celular , Células Cultivadas , Chaperonina 60/genética , Modelos Animais de Doenças , Regulação da Expressão Gênica , Redes Reguladoras de Genes , Humanos , Quinase I-kappa B/metabolismo , Masculino , Proteínas Mitocondriais/genética , Músculo Liso Vascular/lesões , Músculo Liso Vascular/patologia , Miócitos de Músculo Liso/patologia , NF-kappa B/metabolismo , Neointima , Oligonucleotídeos/genética , Oligonucleotídeos/metabolismo , Ratos Sprague-Dawley , Transdução de Sinais , Fatores de Tempo , Transfecção , Remodelação Vascular , Lesões do Sistema Vascular/genética , Lesões do Sistema Vascular/patologiaRESUMO
Cytoplasmic presence of Hsp60, which is principally a nuclear gene-encoded mitochondrial chaperonin, has frequently been stated, but its role in intracellular signaling is largely unknown. In this study, we demonstrate that the cytosolic Hsp60 promotes the TNF-alpha-mediated activation of the IKK/NF-kappaB survival pathway via direct interaction with IKKalpha/beta in the cytoplasm. Selective loss or blockade of cytosolic Hsp60 by specific antisense oligonucleotide or neutralizing antibody diminished the IKK/NF-kappaB activation and the expression of NF-kappaB target genes, such as Bfl-1/A1 and MnSOD, which thus augmented intracellular ROS production and ASK1-dependent cell death, in response to TNF-alpha. Conversely, the ectopic expression of cytosol-targeted Hsp60 enhanced IKK/NF-kappaB activation. Mechanistically, the cytosolic Hsp60 enhanced IKK activation via upregulating the activation-dependent serine phosphorylation in a chaperone-independent manner. Furthermore, transgenic mouse study showed that the cytosolic Hsp60 suppressed hepatic cell death induced by diethylnitrosamine in vivo. The cytosolic Hsp60 is likely to be a regulatory component of IKK complex and it implicates the first mitochondrial factor that regulates cell survival via NF-kappaB pathway.
