WNT-3A regulates an Axin1/NRF2 complex that regulates antioxidant metabolism in hepatocytes

Nuclear factor (erythroid-derived 2)-like 2 (NRF2) is a master regulator of oxidant and xenobiotic metabolism, but it is unknown how it is regulated to provide basal expression of this defense system. Here, we studied the putative connection between NRF2 and the canonical WNT pathway, which modulates hepatocyte metabolism. Results: WNT-3A increased the levels of NRF2 and its transcriptional signature in mouse hepatocytes and HEK293T cells. The use of short interfering RNAs in hepatocytes and mouse embryonic fibroblasts which are deficient in the redox sensor Kelch-like ECH-associated protein 1 (KEAP1) indicated that WNT-3A activates NRF2 in a β-Catenin- and KEAP1-independent manner. WNT-3A stabilized NRF2 by preventing its GSK-3-dependent phosphorylation and subsequent SCF/β-TrCP-dependent ubiquitination and proteasomal degradation. Axin1 and NRF2 were physically associated in a protein complex that was regulated by WNT-3A, involving the central region of Axin1 and the Neh4/Neh5 domains of NRF2. Axin1 knockdown increased NRF2 protein levels, while Axin1 stabilization with Tankyrase inhibitors blocked WNT/NRF2 signaling. The relevance of this novel pathway was assessed in mice with a conditional deletion of Axin1 in the liver, which showed upregulation of the NRF2 signature in hepatocytes and disruption of liver zonation of antioxidant metabolism. Innovation: NRF2 takes part in a protein complex with Axin1 that is regulated by the canonical WNT pathway. This new WNT-NRF2 axis controls the antioxidant metabolism of hepatocytes. Conclusion: These results uncover the participation of NRF2 in a WNT-regulated signalosome that participates in basal maintenance of hepatic antioxidant metabolism

Adaptation and Convergent Evolution within the Jamesonia-Eriosorus Complex in High-Elevation Biodiverse Andean Hotspots

The recent uplift of the tropical Andes (since the late Pliocene or early Pleistocene) provided extensive ecological opportunity for evolutionary radiations. We test for phylogenetic and morphological evidence of adaptive radiation and convergent evolution to novel habitats (exposed, high-altitude páramo habitats) in the Andean fern genera Jamesonia and Eriosorus. We construct time-calibrated phylogenies for the Jamesonia-Eriosorus clade. We then use recent phylogenetic comparative methods to test for evolutionary transitions among habitats, associations between habitat and leaf morphology, and ecologically driven variation in the rate of morphological evolution. Páramo species (Jamesonia) display morphological adaptations consistent with convergent evolution in response to the demands of a highly exposed environment but these adaptations are associated with microhabitat use rather than the páramo per se. Species that are associated with exposed microhabitats (including Jamesonia and Eriorsorus) are characterized by many but short pinnae per frond whereas species occupying sheltered microhabitats (primarily Eriosorus) have few but long pinnae per frond. Pinnae length declines more rapidly with altitude in sheltered species. Rates of speciation are significantly higher among páramo than non-páramo lineages supporting the hypothesis of adaptation and divergence in the unique Páramo biodiversity hotspot

Impact of safety-related dose reductions or discontinuations on sustained virologic response in HCV-infected patients: Results from the GUARD-C Cohort

BACKGROUND: Despite the introduction of direct-acting antiviral agents for chronic hepatitis C virus (HCV) infection, peginterferon alfa/ribavirin remains relevant in many resource-constrained settings. The non-randomized GUARD-C cohort investigated baseline predictors of safety-related dose reductions or discontinuations (sr-RD) and their impact on sustained virologic response (SVR) in patients receiving peginterferon alfa/ribavirin in routine practice. METHODS: A total of 3181 HCV-mono-infected treatment-naive patients were assigned to 24 or 48 weeks of peginterferon alfa/ribavirin by their physician. Patients were categorized by time-to-first sr-RD (Week 4/12). Detailed analyses of the impact of sr-RD on SVR24 (HCV RNA <50 IU/mL) were conducted in 951 Caucasian, noncirrhotic genotype (G)1 patients assigned to peginterferon alfa-2a/ribavirin for 48 weeks. The probability of SVR24 was identified by a baseline scoring system (range: 0-9 points) on which scores of 5 to 9 and <5 represent high and low probability of SVR24, respectively. RESULTS: SVR24 rates were 46.1% (754/1634), 77.1% (279/362), 68.0% (514/756), and 51.3% (203/396), respectively, in G1, 2, 3, and 4 patients. Overall, 16.9% and 21.8% patients experienced 651 sr-RD for peginterferon alfa and ribavirin, respectively. Among Caucasian noncirrhotic G1 patients: female sex, lower body mass index, pre-existing cardiovascular/pulmonary disease, and low hematological indices were prognostic factors of sr-RD; SVR24 was lower in patients with 651 vs. no sr-RD by Week 4 (37.9% vs. 54.4%; P = 0.0046) and Week 12 (41.7% vs. 55.3%; P = 0.0016); sr-RD by Week 4/12 significantly reduced SVR24 in patients with scores <5 but not 655. CONCLUSIONS: In conclusion, sr-RD to peginterferon alfa-2a/ribavirin significantly impacts on SVR24 rates in treatment-naive G1 noncirrhotic Caucasian patients. Baseline characteristics can help select patients with a high probability of SVR24 and a low probability of sr-RD with peginterferon alfa-2a/ribavirin

IL-10 transcription is negatively regulated by BAF180, a component of the SWI/SNF chromatin remodeling enzyme

<p>Abstract</p> <p>Background</p> <p>SWI/SNF chromatin remodeling enzymes play a critical role in the development of T helper lymphocytes, including Th2 cells, and directly program chromatin structure at Th2 cytokine genes. Different versions of SWI/SNF complexes, including BAF and PBAF, have been described based on unique subunit composition. However, the relative role of BAF and PBAF in Th cell function and cytokine expression has not been reported.</p> <p>Results</p> <p>Here we examine the role of the PBAF SWI/SNF complex in Th cell development and gene expression using mice deficient for a PBAF-specific component, BAF180. We find that T cell development in the thymus and lymphoid periphery is largely normal when the BAF180 gene is deleted late in thymic development. However, BAF180-deficient Th2 cells express high levels of the immunoregulatory cytokine IL-10. BAF180 binds directly to regulatory elements in the Il-10 locus but is replaced by BAF250 BAF complexes in the absence of BAF180, resulting in increased histone acetylation and CBP recruitment to the IL-10 locus.</p> <p>Conclusions</p> <p>These results demonstrate that BAF180 is a repressor of IL-10 transcription in Th2 cells and suggest that the differential recruitment of different SWI/SNF subtypes can have direct consequences on chromatin structure and gene transcription.</p

Evolution in the Genus Rhinella: A Total Evidence Phylogenetic Analysis of Neotropical True Toads (Anura: Bufonidae)

True toads of the genus Rhinella are among the most common and diverse group of Neotropical anurans. These toads are widely distributed throughout South America, inhabiting a great diversity of environments and ecoregions. Currently, however, the genus is defined solely on the basis of molecular characters, and it lacks a proper diagnosis. Although some phenetic species groups have traditionally been recognized within Rhinella, the monophyly of some of them have been rejected in previous phylogenetic analyses, and many species remain unassigned to these poorly defined groups. Additionally, the identity and taxonomy of several species are problematic and hinder the specific recognition and description of undescribed taxa. In this work, we first perform phylogenetic analyses of separate mitochondrial and nuclear datasets to test the possible occurrence of hybridiza-tion and/or genetic introgression in the genus. The comparative analysis of both datasets revealed unidirectional mitochondrial introgressions of an unknown parental species into R . horribilis (“ghost introgression”) and of R . dorbignyi into R . bernardoi; therefore, the mitochondrial and nuclear data-sets of these species were considered separately in subsequent analyses. We performed total-evidence phylogenetic analyses that included revised molecular (four mitochondrial and five nuclear genes) and phenotypic (90 characters) datasets for 83 nominal species of Rhinella, plus several undescribed and problematic species and multiple outgroups. Results demonstrate that Rhinella was nonmono-phyletic due to the position of R . ceratophrys, which was recovered as the sister taxon of Rhaebo nasicus with strong support. Among our outgroups, the strongly supported Anaxyrus + Incilius is the sister clade of all other species of Rhinella. Once R . ceratophrys is excluded, the genus Rhinellais monophyletic, well supported, and composed of two major clades. One of these is moderately supported and includes species of the former R . spinulosa Group (including R . gallardoi); the mono-phyletic R . granulosa, R . crucifer, and R . marina Groups; and a clade composed of the mitochondrial sequences of R . horribilis. The other major clade is strongly supported and composed of all the spe-cies from the non-monophyletic R . veraguensis and R . margaritifera Groups, the former R . acrolophaGroup, and R . sternosignata. Consistent with these results, we define eight species groups of Rhinella that are mostly diagnosed by phenotypic synapomorphies in addition to a combination of morpho-logical character states. Rhinella sternosignata is the only species that remains unassigned to any group. We also synonymize nine species, treat three former subspecies as full species, and suggest that 15 lineages represent putative undescribed species. Lastly, we discuss the apparently frequent occurrence of hybridization, deep mitochondrial divergence, and “ghost introgression”; the incomplete phenotypic evidence (including putative character systems that could be used for future phy-logenetic analyses); and the validity of the known fossil record of Rhinella as a source of calibration points for divergence dating analyses.Peer reviewe

Effect of inhibition of the protein tyrosine phosphatase 1B in lipotoxicity in liver progenitor oval cells

Resumen del póster presentado al 42nd Congress of the Spanish Society of Biochemistry and Molecular Biology (SEBBM), celebrado en Madrid del 16 al 19 de julio de 2019.Oval cells are progenitor cells with an emerging role in liver regenerative responses. However, their susceptibility to lipotoxicity in obesity-associated insulin resistance is unknown. Inhibition of protein tyrosine phosphatase 1B (PTP1B), a negative modulator of insulin signaling, is a pharmacological strategy against insulin resistance/obesity. Ours aims were to identify whether oval cells are insulin target cells and to analyze the impact of PTP1B deficiency in their susceptibility to lipotoxicity in the context of obesity-associated non-alcoholic fatty liver disease (NAFLD). For lipotoxicity studies, oval cells were treated with palmitic acid (PA) for different time-periods, after which oxidative/endoplasmic reticulum (ER) stress responses and autophagy/apoptosis markers were analyzed. A lipidomic study was conducted to characterize the intracellular lipid species upon PA stimulation. Oval cells responded to insulin by inducing insulin receptor tyrosine phosphorylation, this effect being higher in the absence of PTP1B. Treatment with PA induced apoptotic cell death in PTP1B+/+ oval cells in parallel with a blockade of the autophagy flux. Cell death was not found in PTP1B-/- cells that accumulated lipid droplets and increased perilipin2 levels upon PA treatment. Cell death in PA-treated PTP1B+/+ oval cells was prevented by cotreatment with sulforaphane, a Nrf2 activator. Also, PTP1B-/- oval cells showed higher basal levels of HO-1 and catalase, suggesting constitutive anti-oxidant defense. An early activation of ER stress was found in both genotypes but this response was enhanced in PTP1B-/- cells in both basal and upon PA treatment. Lipidomics revealed that PTP1B-/- oval cells accumulated triglyceride species and cholesterol esters in response to PA. By contrast, PTP1B+/+ oval cells showed higher diacylglycerides, more toxic lipid species. In conclusion, we have revealed that oval cells are insulin target cells susceptible to lipotoxicity, an effect mediated at least in part by the induction of oxidative stress. PTP1B deficiency protects against lipotoxic cell death by mechanisms including enhancement of anti-oxidant defences and capacity to accumulate TG containing lipid droplets, suggesting a potential benefit in cellular regenerative therapies against NAFLD.Peer reviewe

Role of PTP1B in the progression of non-alcoholic fatty liver disease

Resumen del póster presentado al 13th International Symposium on Insulin Receptor and Insulin Action, celebrado en Niza (Francia) del 20 al 22 de abril de 2017.[Background and aims]: Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in Western countries. Protein tyrosine phosphatase 1B (PTP1B) negatively modulates insulin receptor-mediated signalling and is a therapeutic target for type 2 diabetes and obesity. We have evaluated the impact of PTP1B deftciency in non-alcoholic steatohepatitis (NASH), a severe NAFLD stage. [Materials and Methods]: Histological and molecular characterization of livers from wild-type and PTP1B-deficient mice fed chow (CHD) or methionine/choline-deficient diet (MCD) for 4-8 weeks. A NASH recovery model was established by switching MCD (after 8 weeks) to CHD for 2-7 days. Non-parenchymal liver cells (NPCs) were analyzed by flow cytometry. Oval cells (OCs) were isolated from mouse livers. PTP1B and OCs markers were analyzed in livers from mice, and NASH patients compared to normal livers. [Results]: Wild-type mice fed MCD for 8 weeks exhibited severe NASH with inftltration of NPCs and increased Fgf21, ll6 and ll1b mRNAs in the liver. These parameters returned to normal levels after switching to CHD. PTP1B deficiency accelerated MCD-induced NASH reflected by liver histology and higher increases in NPCs infiltration, and Fgf21 and ll6 mRNAs. Conversely, after switching to CHD, PTP1B deftciency rapidly improved liver histology and fat deposition decreased earlier than in wild-type mice in parallel with higher Cd36 and Cpt1a mRNAs, and serum triglycerides, suggesting increased fatty acid efflux from the liver. Recruitment of NK+ cells and M2 macrophage markers Nere also up-regulated in PTP1B-deficient compared to wild-type livers. lnterestingly, expression of OCs markers (Epcam and Ck19) increased by MCD in both genotypes, being this effect enhanced in PTP1B-deficient livers. OCs lacking PTP1B displayed enhanced proliferative capacity. In NASH patients, hepatic PTP1B mRNA levels correlated with OCs markers. [Conclusion]: PTP1B elicits an opposite role in NASH progression and regression, and might modulate oval cells proliferation during NAFLD progression.Peer Reviewe

Dual Role of PTP1B in the progression and reversión of non-alcoholic steatohepatitis

Trabajo presentado en el EMBO Workshop: "Metabotic disorders and liver cancer", celebrado en Palma de Mallorca, del 23 al 26 de abril de 2017Background and aims: Non-alcoholic fatty river disease (NAFLD) is the most common chronic liver disease in western countries. protein tyrosine phosphatur" tn lrretn¡ negatively modulates insulin receptor-mediated signaling uld.i:. l therapeuiic targer for type 2 díauetls -i "L-".iiv.'w" ¡r"" evaluated the impact of prplB sl.age. deficiency r, non-utcJ¡oü" steatohepatitis (NASH), a severe NAFLD Materials PTPlB-deficient and Methods: Histological and molecurar characterization of livers from w,d-type and mice fed ctrow lcHo¡ or methionine/cholir"-a.n"r*, a-i"i iü"crJi.. ols" ',J""n, NASH recovery o model was established by switching MC¡ parenchymal i"ir.. s *""t9 ro érro r- )-z á"vr. N", liver cells (NpCs) were analyzed by flów "y,o-"try. (Jval mouse livers. prplB cells 1OCs.¡ were isolated liom and oCs markers were Áaryzed-in liveis from compared -i""'unJñasn pá,iir, ,ra to normal livers. Results: wild-type mice fed MCD for 8 weeks exhibited severe NASH with inñltration of NpCs and increased Fgf21' 116 and Illb mRNAs in.the river. rir.i" p*"."t"., retumed ro normal revers after swirching ro cHD. prplB deficiency accelerated MCD-ináíü Nasg."nected by liver histology and higher increases in NpCs infirtration and Fgf21 ur¿ uo PTPIB. -n¡a1. conversely, after switching to cHD, deficiencl Tpid]y improved liver hlistology and iar aeposition decreased earlier rhan in wild- type mice in parallel with higher cd36 and Cptla irRNe, *J ,'"-,o t.igrycerides, fatty ,rg!"rti;g i;."ur"a acid efflux from the liver. Recruitment of Nr* ""rl-urJi,rz ,ruó.-.ópr,ug. Á;¿?;";;?;;r" ,p- regulated in PTPlB-deficient compared to wild-type tive.s. inte.estingly, expression of oCs markers (Epcam and Cklg) increased r," MCD.in uotn genotypes. i,is'Lrrect being enhanced prplB-deficient livers' ocs lacking prplB dísplayed_ enhancJo p.áiir".u,i*' "apacity. In NASH parients, hepatic PTPTB mRNA levels conelated with OCs markers. - Conclusion: PTPIB elicits u, "ppit" role in NASH progression and regression and might modulate oval cells prolilerarion auring NAFLO progression.Peer reviewe

Protein tyrosine phosphatase 1B modulates GSK3b/Nrf2 and IGFIR signaling pathways in acetaminophen-induced hepatotoxicity

Acute hepatic failure secondary to acetaminophen (APAP) poisoning is associated with high mortality. Protein tyrosine phosphatase 1B (PTP1B) is a negative regulator of tyrosine kinase growth factor signaling. In the liver, this pathway confers protection against injury. However, the involvement of PTP1B in the intracellular networks activated by APAP is unknown. We have assessed PTP1B expression in APAP-induced liver failure in humans and its role in the molecular mechanisms that regulate the balance between cell death and survival in human and mouse hepatocytes, as well as in a mouse model of APAPinduced hepatotoxicity. PTP1B expression was increased in human liver tissue removed during liver transplant from patients for APAP overdose. PTP1B was upregulated by APAP in primary human and mouse hepatocytes together with the activation of c-jun (NH2) terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38 MAPK), resulting in cell death. Conversely, Akt phosphorylation and the antiapoptotic Bcl2 family members BclxL and Mcl1 were decreased. PTP1B deficiency in mouse protects hepatocytes against APAP-induced cell death, preventing glutathione depletion, reactive oxygen species (ROS) generation and activation of JNK and p38 MAPK. APAP-treated PTP1B-/- hepatocytes showed enhanced antioxidant defense through the glycogen synthase kinase 3 (GSK3)b/Src kinase family (SKF) axis, delaying tyrosine phosphorylation of the transcription factor nuclear factor-erythroid 2-related factor (Nrf2) and its nuclear exclusion, ubiquitination and degradation. Insulin-like growth factor-I receptor-mediated signaling decreased in APAP-treated wild-type hepatocytes, but was maintained in PTP1B-/- cells or in wild-type hepatocytes with reduced PTP1B levels by RNA interference. Likewise, both signaling cascades were modulated in mice, resulting in less severe APAP hepatotoxicity in PTP1B-/- mice. Our results demonstrated that PTP1B is a central player of the mechanisms triggered by APAP in hepatotoxicity, suggesting a novel therapeutic target against APAPinduced liver failure. © 2013 Macmillan Publishers Limited. All rights reserved.We acknowledge the following grant support: SAF2012-33283 (MINECO, Spain), Comunidad de Madrid S2010/BMD-2423, EFSD and Amylin Paul Langerhans Grant and Centro de Investigaciones Biomédicasen Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM, ISCIII, Spain) (to AMV); SAF2012-38048 (MINECO, Spain) (to JM-P); PI09/0185 and Centro de Investigacion Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD, ISCIII, Spain) (to JM); AGL2010-17579 (MINECO, Spain) (to LG); and SAF2010-17822 (MINECO, Spain) (to AC).Peer Reviewe