Augmented Wnt signaling as a therapeutic tool to prevent ischemia/reperfusion injury in liver: Preclinical studies in a mouse model.
The Wnt signaling pathway has established biological roles in liver development, regeneration, and carcinogenesis. Given the common need for cellular energy utilization in each of these processes, we hypothesized that Wnt signaling would directly regulate hepatocyte mitochondrial function. Mice were engineered to overexpress Wnt1 in hepatocytes under the control of a tetracycline analogue. Wnt1 and wild-type mice underwent ischemia/reperfusion injury (IRI) to induce oxidative mitochondrial injury. Alpha mouse liver 12 (AML12) hepatocytes were exposed to Wnt agonists for in vitro hypoxia/reoxygenation (H-R) experiments. We observed stabilized mitochondrial membrane potential and reduced levels of hepatocyte apoptosis involving the mitochondrial pathway in Wnt1 mice compared to controls following IRI. Wnt1 mice also demonstrated increased mitochondrial DNA copy number, as well as an increased tricarboxylic acid cycle activity and adenosine triphosphate levels indicating that mitochondrial function is preserved by Wnt1 overexpression following IRI. AML12 cells treated by Wnt3a or the glycogen synthase kinase 3β inhibitor LiCl exposed to H-R demonstrated decreased reactive oxygen species and reduced apoptosis compared to controls. Increased nucleus-localized PGC-1α and phosphorylated SIRT1 was observed in both Wnt1+ mice as well as AML12 cells treated with Wnt3a or LiCl. Activated Wnt signaling protects hepatocytes against oxidative injury and apoptosis through mitochondrial stabilization and preserved oxidative phosphorylation function. Mechanistically, these effects are accompanied by an increase in phosphorylated SIRT1 and nucleus-localized PGC-1α. These findings expand the understanding of Wnt signaling biology in hepatocytes and suggest the potential for the therapeutic application of Wnt pathway manipulation in a variety of clinical applications including organ transplantation.
Division of Pediatric Surgery, Stanford University School of Medicine, Stanford, CA.
Bowen
B
Liu
Division of Pediatric Surgery, Stanford University School of Medicine, Stanford, CA.
Rong
R
Zhang
Division of Pediatric Surgery, Stanford University School of Medicine, Stanford, CA.
Guozhong
G
Tao
Division of Pediatric Surgery, Stanford University School of Medicine, Stanford, CA.|Department of General, Visceral and Pediatric Surgery, School of Medicine, Heinrich Heine University, Düsseldorf, Germany.
Nadja Corinna
NC
Lehwald
Division of Pediatric Surgery, Stanford University School of Medicine, Stanford, CA.
Bo
B
Liu
Division of Pediatric Surgery, Stanford University School of Medicine, Stanford, CA.
Yangseok
Y
Koh
Division of Pediatric Surgery, Stanford University School of Medicine, Stanford, CA.|Lucile Packard Children's Hospital Stanford, Stanford, CA.
Karl G
KG
Sylvester
D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D004195:Disease Models, Animal; D004734:Energy Metabolism; D008107:Liver Diseases / Q000378:metabolism / Q000517:prevention & control*; D008822:Mice, Transgenic; D008928:Mitochondria / Q000378:metabolism; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D017382:Reactive Oxygen Species / Q000378:metabolism; D015427:Reperfusion Injury / Q000378:metabolism / Q000517:prevention & control*; D056564:Sirtuin 1 / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D051153:Wnt Proteins / Q000378:metabolism; D051155:Wnt1 Protein / Q000378:metabolism*; D060509:Wnt3A Protein / Q000378:metabolism
D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C485290:Ppargc1a protein, mouse; D017382:Reactive Oxygen Species; D014157:Transcription Factors; D051153:Wnt Proteins; D051155:Wnt1 Protein; C495246:Wnt1 protein, mouse; D060509:Wnt3A Protein; C555511:Wnt3a protein, mouse; C470545:Sirt1 protein, mouse; D056564:Sirtuin 1