TY - JOUR
T1 - KEAP1-NRF2 complex in ischemia-induced hepatocellular damage of mouse liver transplants
AU - Ke, Bibo
AU - Shen, Xiu Da
AU - Zhang, Yu
AU - Ji, Haofeng
AU - Gao, Feng
AU - Yue, Shi
AU - Kamo, Naoko
AU - Zhai, Yuan
AU - Yamamoto, Masayuki
AU - Busuttil, Ronald W.
AU - Kupiec-Weglinski, Jerzy W.
N1 - Funding Information:
NIH Grant DK 062357 ; The Diann Kim and The Dumont Research Foundations.
PY - 2013/12
Y1 - 2013/12
N2 - Background & Aims The Keap1-Nrf2 signaling pathway regulates host cell defense responses against oxidative stress and maintains the cellular redox balance. Methods We investigated the function/molecular mechanisms by which Keap1-Nrf2 complex may influence liver ischemia/reperfusion injury (IRI) in a mouse model of hepatic cold storage (20 h at 4 C) followed by orthotopic liver transplantation (OLT). Results The Keap1 hepatocyte-specific knockout (HKO) in the donor liver ameliorated post-transplant IRI, evidenced by improved hepatocellular function and OLT outcomes (Keap1 HKO→Keap1 HKO; 100% survival), as compared with controls (WT→WT; 50% survival; p <0.01). By contrast, donor liver Nrf2 deficiency exacerbated IRI in transplant recipients (Nrf2 KO→Nrf2 KO; 40% survival). Ablation of Keap1 signaling reduced macrophage/neutrophil trafficking, pro-inflammatory cytokine programs, and hepatocellular necrosis/apoptosis, while simultaneously promoting anti-apoptotic functions in OLTs. At the molecular level, Keap1 HKO increased Nrf2 levels, stimulated Akt phosphorylation, and enhanced expression of anti-oxidant Trx1, HIF-1α, and HO-1. Pretreatment of liver donors with PI3K inhibitor (LY294002) disrupted Akt/HIF-1A signaling and recreated hepatocellular damage in otherwise IR-resistant Keap1 HKO transplants. In parallel in vitro studies, hydrogen peroxide-stressed Keap1-deficient hepatocytes were characterized by enhanced expression of Nrf2, Trx1, and Akt phosphorylation, in association with decreased release of lactate dehydrogenase (LDH) in cell culture supernatants. Conclusions Keap1-Nrf2 complex prevents oxidative injury in IR-stressed OLTs through Keap1 signaling, which negatively regulates Nrf2 pathway. Activation of Nrf2 induces Trx1 and promotes PI3K/Akt, crucial for HIF-1α activity. HIF-1α-mediated overexpression of HO-1/Cyclin D1 facilitates cytoprotection by limiting hepatic inflammatory responses, and hepatocellular necrosis/apoptosis in a PI3K-dependent manner.
AB - Background & Aims The Keap1-Nrf2 signaling pathway regulates host cell defense responses against oxidative stress and maintains the cellular redox balance. Methods We investigated the function/molecular mechanisms by which Keap1-Nrf2 complex may influence liver ischemia/reperfusion injury (IRI) in a mouse model of hepatic cold storage (20 h at 4 C) followed by orthotopic liver transplantation (OLT). Results The Keap1 hepatocyte-specific knockout (HKO) in the donor liver ameliorated post-transplant IRI, evidenced by improved hepatocellular function and OLT outcomes (Keap1 HKO→Keap1 HKO; 100% survival), as compared with controls (WT→WT; 50% survival; p <0.01). By contrast, donor liver Nrf2 deficiency exacerbated IRI in transplant recipients (Nrf2 KO→Nrf2 KO; 40% survival). Ablation of Keap1 signaling reduced macrophage/neutrophil trafficking, pro-inflammatory cytokine programs, and hepatocellular necrosis/apoptosis, while simultaneously promoting anti-apoptotic functions in OLTs. At the molecular level, Keap1 HKO increased Nrf2 levels, stimulated Akt phosphorylation, and enhanced expression of anti-oxidant Trx1, HIF-1α, and HO-1. Pretreatment of liver donors with PI3K inhibitor (LY294002) disrupted Akt/HIF-1A signaling and recreated hepatocellular damage in otherwise IR-resistant Keap1 HKO transplants. In parallel in vitro studies, hydrogen peroxide-stressed Keap1-deficient hepatocytes were characterized by enhanced expression of Nrf2, Trx1, and Akt phosphorylation, in association with decreased release of lactate dehydrogenase (LDH) in cell culture supernatants. Conclusions Keap1-Nrf2 complex prevents oxidative injury in IR-stressed OLTs through Keap1 signaling, which negatively regulates Nrf2 pathway. Activation of Nrf2 induces Trx1 and promotes PI3K/Akt, crucial for HIF-1α activity. HIF-1α-mediated overexpression of HO-1/Cyclin D1 facilitates cytoprotection by limiting hepatic inflammatory responses, and hepatocellular necrosis/apoptosis in a PI3K-dependent manner.
KW - HO-1
KW - Keap1-Nrf2 redox system
KW - Liver ischemia/reperfusion injury
KW - Liver transplantation
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U2 - 10.1016/j.jhep.2013.07.016
DO - 10.1016/j.jhep.2013.07.016
M3 - Article
C2 - 23867319
AN - SCOPUS:84887997385
SN - 0168-8278
VL - 59
SP - 1200
EP - 1207
JO - Journal of Hepatology
JF - Journal of Hepatology
IS - 6
ER -