Work

PTEN-mediated akt/β-Catenin/foxo1 signaling regulates innate immune responses in mouse liver ischemia/reperfusion injury

Year: 2012

Type: article

Abstract: UNLABELLED: The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) regulates innate immune responses inversely with phosphoinositide 3-kinase (PI3K) and its direct downstream target gene, Akt. The Forkhead box O (Foxo) transcription factors are essential in the regulation of tissue development, immune homeostasis, and cell survival. This study was designed to investigate the role of PTEN-mediated Akt/β-catenin/Foxo1 signaling in the regulation of in vivo and in vitro innate immune responses in a mouse model of hepatic inflammatory injury induced by 90 minutes of liver partial warm ischemia followed by 6 hours of reperfusion. We found that knockdown of PTEN with small interfering RNA (siRNA) promoted Akt/β-catenin/Foxo1 signaling, leading to resistance against liver ischemia/reperfusion (IR) damage, local enhancement of antiapoptotic function, and downregulation of innate Toll-like receptor 4 (TLR4) expression. A specific PI3K blockade inhibited Akt/β-catenin signaling, increased Foxo1-mediated TLR4-driven local inflammation, and recreated cardinal features of liver IR injury. Moreover, knockdown of PTEN in lipopolysaccharide-stimulated mouse bone marrow-derived macrophages enhanced β-catenin activity, which in turn provided a negative regulatory feedback to the Foxo1 function, leading to the inhibition of TLR4 and NF-κB, with ultimate depression of proinflammatory cytokine programs in vitro. CONCLUSION: Our novel findings identify the PTEN-mediated Akt/β-catenin/Foxo1 axis as a key regulator of innate inflammatory response in the mouse liver. By identifying molecular mechanisms of PTEN-mediated Akt/β-catenin/Foxo1 signaling in TLR4 innate immune regulation, our study provides a rationale for therapeutic approaches to manage inflammation injury in IR-stressed liver.

Source: Hepatology

DOI: 10.1002/hep.25958

Authors: Naoko Kamo, Bibo Ke, Ronald W. Busuttil, Jerzy W. Kupiec-Weglinski

Institution: University of California, Los Angeles

Language: English

Topic: Organ Transplantation Techniques and Outcomes

Subfield: Surgery

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: bronze

Funders: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases