title: Significant lethality following liver resection in A20 heterozygous knockout mice uncovers a key role for A20 in liver regeneration.
abstract: Hepatic expression of A20, including in hepatocytes, increases in response to injury, inflammation and resection. This increase likely serves a hepatoprotective purpose. The characteristic unfettered liver inflammation and necrosis in A20 knockout mice established physiologic upregulation of A20 as integral to the anti-inflammatory and anti-apoptotic armamentarium of hepatocytes. However, the implication of physiologic upregulation of A20 in modulating hepatocytes' proliferative responses following liver resection remains controversial. To resolve the impact of A20 on hepatocyte proliferation and the liver's regenerative capacity, we examined whether decreased A20 expression, as in A20 heterozygous knockout mice, affects outcome following two-third partial hepatectomy. A20 heterozygous mice do not demonstrate a striking liver phenotype, indicating that their A20 expression levels are still sufficient to contain inflammation and cell death at baseline. However, usually benign partial hepatectomy provoked a staggering lethality (>40%) in these mice, uncovering an unsuspected phenotype. Heightened lethality in A20 heterozygous mice following partial hepatectomy resulted from impaired hepatocyte proliferation due to heightened levels of cyclin-dependent kinase inhibitor, p21, and deficient upregulation of cyclins D1, E and A, in the context of worsened liver steatosis. A20 heterozygous knockout minimally affected baseline liver transcriptome, mostly circadian rhythm genes. Nevertheless, this caused differential expression of >1000 genes post hepatectomy, hindering lipid metabolism, bile acid biosynthesis, insulin signaling and cell cycle, all critical cellular processes for liver regeneration. These results demonstrate that mere reduction of A20 levels causes worse outcome post hepatectomy than full knockout of bona fide liver pro-regenerative players such as IL-6, clearly ascertaining A20's primordial role in enabling liver regeneration. Clinical implications of these data are of utmost importance as they caution safety of extensive hepatectomy for donation or tumor in carriers of A20/TNFAIP3 single nucleotide polymorphisms alleles that decrease A20 expression or function, and prompt the development of A20-based liver pro-regenerative therapies.
authors.affiliation: Division of Vascular Surgery, Center for Vascular biology Research and the Transplant Institute, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.|Department of Visceral Surgery and Medicine, University Hospital Bern, Bern, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Studer
authors.affiliation: Division of Vascular Surgery, Center for Vascular biology Research and the Transplant Institute, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: C G
authors.initials: CG
authors.lastname: da Silva
authors.affiliation: Division of Vascular Surgery, Center for Vascular biology Research and the Transplant Institute, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Revuelta Cervantes
authors.affiliation: Division of Vascular Surgery, Center for Vascular biology Research and the Transplant Institute, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: A
authors.initials: A
authors.lastname: Mele
authors.affiliation: Division of Vascular Surgery, Center for Vascular biology Research and the Transplant Institute, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: E
authors.initials: E
authors.lastname: Csizmadia
authors.affiliation: Division of Vascular Surgery, Center for Vascular biology Research and the Transplant Institute, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Siracuse
authors.affiliation: Division of Vascular Surgery, Center for Vascular biology Research and the Transplant Institute, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Damrauer
authors.affiliation: Division of Vascular Surgery, Center for Vascular biology Research and the Transplant Institute, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: C R
authors.initials: CR
authors.lastname: Peterson
authors.affiliation: Department of Visceral Surgery and Medicine, University Hospital Bern, Bern, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Candinas
authors.affiliation: Department of Visceral Surgery and Medicine, University Hospital Bern, Bern, Switzerland.
authors.forename: D M
authors.initials: DM
authors.lastname: Stroka
authors.affiliation: Division of Interdisciplinary Medicine and Biotechnology, Bioinformatics core, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: A
authors.initials: A
authors.lastname: Ma
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of California in San Francisco, San Fransisco, CA, USA.
authors.forename: M
authors.initials: M
authors.lastname: Bhasin
authors.affiliation: Division of Vascular Surgery, Center for Vascular biology Research and the Transplant Institute, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: C
authors.initials: C
authors.lastname: Ferran
mesh_terms: D000818:Animals; D017209:Apoptosis; D049109:Cell Proliferation; D019925:Cyclin A / Q000378:metabolism; D019938:Cyclin D1 / Q000378:metabolism; D019927:Cyclin E / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D006498:Hepatectomy; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D050356:Lipid Metabolism; D008099:Liver / Q000378:metabolism* / Q000601:surgery; D008115:Liver Regeneration; D051379:Mice; D018345:Mice, Knockout; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D019925:Cyclin A; D019927:Cyclin E; D050759:Cyclin-Dependent Kinase Inhibitor p21; D015850:Interleukin-6; D047908:Intracellular Signaling Peptides and Proteins; D014409:Tumor Necrosis Factor-alpha; D019938:Cyclin D1; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D003546:Cysteine Endopeptidases; C513261:Tnfaip3 protein, mouse