BACKGROUND & AIMSThe nuclear factor of activated T-cells (NFAT) plays an important role in immune responses by regulating the expression of inflammatory genes. However, it is not known whether NFAT plays any role in the bile acid (BA)-induced hepatic inflammatory response. Thus, we aimed to examine the functional role of NFATc3 in cholestatic liver injury in mice and humans.METHODSGene and protein expression and cellular localization were assessed in primary hepatocyte cultures (mouse and human) and cholestatic liver tissues (murine models and patients with primary biliary cholangitis [PBC] or primary sclerosing cholangitis [PSC]) by quantitative PCR, western blot and immunohistochemistry. Specific NFAT inhibitors were used in vivo and in vitro. Gene reporter assays and ChIP-PCR were used to determine promoter activity.RESULTSNFAT isoforms c1 and c3 were expressed in human and mouse hepatocytes. When treated with cholestatic levels of BAs, nuclear translocation of NFATc3 was increased in both human and mouse hepatocytes and was associated with elevated mRNA levels of IL-8, CXCL2, and CXCL10 in these cells. Blocking NFAT activation with pathway-specific inhibitors or knocking down Nfatc3 expression significantly decreased BA-driven induction of these cytokines in mouse hepatocytes. Nuclear expression of NFATc3/Nfatc3 protein was increased in cholestatic livers, both in mouse models (bile duct ligation or Abcb4^-/- mice) and in patients with PBC and PSC in association with elevated tissue levels of Cxcl2 (mice) or IL-8 (humans). Gene reporter assays and ChIP-PCR demonstrated that the NFAT response element in the IL-8 promoter played a key role in BA-induced human IL-8 expression. Finally, blocking NFAT activation in vivo in Abcb4^-/- mice reduced cholestatic liver injury.CONCLUSIONSNFAT plays an important role in BA-stimulated hepatic cytokine expression in cholestasis. Blocking hepatic NFAT activation may reduce cholestatic liver injury in humans.LAY SUMMARYBile acid induces liver injury by stimulating the expression of inflammatory genes in hepatocytes through activation of the transcription factor NFAT. Blocking this activation in vitro (in hepatocyte cultures) and in vivo (in cholestatic mice) decreased the expression of inflammatory genes and reduced liver injury.

2018-09-01·Cellular Signalling3区 · 生物学

EphA2 stimulates VCAM-1 expression through calcium-dependent NFAT1 activity

3区 · 生物学

Article

作者: Pattillo, Christopher B ; Orr, A Wayne ; Yurdagul, Arif ; Finney, Alexandra C ; Funk, Steven Daniel

Endothelial cell activation by proinflammatory stimuli drives leukocyte recruitment through enhanced expression of counter-receptors such as vascular cell adhesion molecule-1 (VCAM-1). We previously demonstrated that activation of the receptor tyrosine kinase EphA2 with its ligand ephrin-A1 induces VCAM-1 expression. Here, we sought to characterize the proinflammatory signaling pathways involved. Analysis of over-represented transcription factors in ephrin-A1-induced genes identified multiple potential transcriptional regulators, including the Rel family members nuclear factor-κB (NF-κB/p65) and nuclear factor of activated T-cells (NFAT). While ephrin-A1 failed to induce endothelial NF-κB activation, NF-κB inhibitors prevented ephrin-A1-induced VCAM-1 expression, suggesting basal NF-κB activity is required. In contrast, ephrin-A1 induced a robust EphA2-dependent increase in NFAT activation, and mutation of the NF-κB/NFAT-binding sites in the VCAM-1 promoter blunted ephrin-A1-induced promoter activity. NFAT activation classically occurs through calcium-dependent calcineurin activation, and inhibiting NFAT signaling with calcineurin inhibitors (cyclosporine A, FK506) or direct NFAT inhibitors (A-285222) was sufficient to block ephrin-A1-induced VCAM-1 expression. Consistent with robust NFAT activation, ephrin-A1-induced an EphA2-dependent calcium influx in endothelial cells that was required for ephrin-A1-induced NFAT activation and VCAM-1 expression. This work provides the first data showing EphA2-dependent calcium influx and NFAT activation and identifies NFAT as a novel EphA2-dependent proinflammatory pathway in endothelial activation.

2016-12-01·Journal of Neurochemistry2区 · 医学

Pasireotide prevents nuclear factor of activated T cells nuclear translocation and acts as a protective agent in aminoglycoside‐induced auditory hair cell loss

2区 · 医学

Article

作者: Bodmer, Daniel ; Petkovic, Vesna ; Wright, Matthew B. ; Perkovic, Adrijana ; Sekulic‐Jablanovic, Marijana

AbstractHearing impairment is a global health problem with a high socioeconomic impact. Damage to auditory hair cells (HCs) in the inner ear as a result of aging, disease, trauma, or toxicity, underlies the majority of cases of sensorineural hearing loss. Previously we demonstrated that the Ca2+‐sensitive neuropeptide, somatostatin (SST), and an analog, octreotide, protect HCs from gentamicin‐induced cell death in vitro. Aminoglycosides such as gentamicin trigger a calcium ion influx (Ca2+) that activates pro‐apoptotic signaling cascades in HCs. SST binding to the G‐protein‐coupled receptors (SSTR1‐SSTR5) that are directly linked to voltage‐dependent Ca2+ channels inhibits Ca2+ channel activity and associated downstream events. Here, we report that the SST analog pasireotide, a high affinity ligand to SSTRs 1–3, and 5, with a longer half‐life than octreotide, prevents gentamicin‐induced HC death in the mouse organ of Corti (OC). Explant experiments using OCs derived from SSTR1 and SSTR1and 2 knockout mice, revealed that SSTR2 mediates pasireotide's anti‐apoptotic effects. Mechanistically, pasireotide prevented a nuclear translocation of the Ca2+‐sensitive transcription factor, nuclear factor of activated T cells (NFAT), which is ordinarily provoked by gentamicin in OC explants. Direct inhibition of NFAT with 11R‐VIVIT also prevented the gentamicin‐dependent nuclear translocation of NFAT and apoptosis. Both pasireotide and 11R‐VIVIT partially reversed the effects of gentamicin on the expression of downstream survival targets (NMDA receptor and the regulatory subunit of phosphatidylinositol‐4,5‐bisphosphate 3‐kinase, PI3K). These data suggest that SST analogs antagonize aminoglycoside‐induced cell death in an NFAT‐dependent fashion. SST analogs and NFAT inhibitors may therefore offer new therapeutic possibilities for the treatment of hearing loss.

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100 项与 NFAT inhibitor(Imagene) 相关的药物交易

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