title: Protein-tyrosine phosphatase 1B deficiency protects against Fas-induced hepatic failure.
abstract: Genetic disruption of protein-tyrosine phosphatase 1B (PTP1B) in mice leads to increased insulin sensitivity and resistance to weight gain. Although PTP1B has been implicated as a regulator of multiple signals, its function in other physiological responses in vivo is poorly understood. Here we demonstrate that PTP1B-null mice are resistant to Fas-induced liver damage and lethality, as evident by reduced hepatic apoptosis in PTP1B-null versus wild type mice and reduced levels of circulating liver enzymes. Activation of pro-apoptotic caspases-8, -9, -3, and -6 was attenuated in livers from PTP1B-null mice following Fas receptor stimulation, although components of the death-inducing signaling complex were intact. Activation of anti-apoptotic regulators, such as the hepatocyte growth factor/Met receptor tyrosine kinase, as well as Raf, ERK1/2, FLIP(L), and the NF-kappaB pathway, was elevated in response to Fas activation in livers from PTP1B-null mice. Using PTP1B-deficient primary hepatocytes, we show that resistance to Fas-mediated apoptosis is cell autonomous and that signals involving the Met, ERK1/2, and NF-kappaB pathways are required for cytoprotection. This study identifies a previously unknown physiological role for PTP1B in Fas-mediated liver damage and points to PTP1B as a potential therapeutic target against hepatotoxic agents.
authors.affiliation: Department of Biochemistry, McGill University, Montréal, Québec, Canada.
authors.forename: Veena
authors.initials: V
authors.lastname: Sangwan
authors.forename: Grigorios N
authors.initials: GN
authors.lastname: Paliouras
authors.forename: Alan
authors.initials: A
authors.lastname: Cheng
authors.forename: Nadia
authors.initials: N
authors.lastname: Dubé
authors.forename: Michel L
authors.initials: ML
authors.lastname: Tremblay
authors.forename: Morag
authors.initials: M
authors.lastname: Park
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology; D020169:Caspases / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D053222:Fas Ligand Protein; D005260:Female; D022781:Hepatocytes / Q000378:metabolism / Q000473:pathology; D008099:Liver / Q000201:enzymology* / Q000473:pathology; D017093:Liver Failure / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008817:Mice, Mutant Strains; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D013950:Thymus Gland / Q000166:cytology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D048069:Tumor Necrosis Factors / Q000378:metabolism; D019014:fas Receptor / Q000276:immunology / Q000378:metabolism*
chemical_list: D000906:Antibodies; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D048069:Tumor Necrosis Factors; D019014:fas Receptor; D048049:Extracellular Signal-Regulated MAP Kinases; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; C516609:Ptpn1 protein, mouse; D020169:Caspases