127 research outputs found
Hepatocyte IKK2 Protects Mdr2â/â Mice from Chronic Liver Failure
Mice lacking the Abc4 protein encoded by the multidrug resistance-2 gene (Mdr2â/â) develop chronic periductular inflammation and cholestatic liver disease resulting in the development of hepatocellular carcinoma (HCC). Inhibition of NF-ÎșB by expression of an IÎșBα super-repressor (IÎșBαSR) transgene in hepatocytes was shown to prevent HCC development in Mdr2â/â mice, suggesting that NF-ÎșB acts as a tumour promoter in this model of inflammation-associated carcinogenesis. On the other hand, inhibition of NF-ÎșB by hepatocyte specific ablation of IKK2 resulted in increased liver tumour development induced by the chemical carcinogen DEN. To address the role of IKK2-mediated NF-ÎșB activation in hepatocytes in the pathogenesis of liver disease and HCC in Mdr2â/â mice, we generated Mdr2-deficient animals lacking IKK2 specifically in hepatocytes using the Cre-loxP system. Mdr2â/â mice lacking IKK2 in hepatocytes developed spontaneously a severe liver disease characterized by cholestasis, major hyperbilirubinemia and severe to end-stage fibrosis, which caused muscle wasting, loss of body weight, lethargy and early spontaneous death. Cell culture experiments showed that primary hepatocytes lacking IKK2 were more sensitive to bile acid induced death, suggesting that hepatocyte-specific IKK2 deficiency sensitized hepatocytes to the toxicity of bile acids under conditions of cholestasis resulting in greatly exacerbated liver damage. Mdr2â/âIKK2Hep-KO mice remarkably recapitulate chronic liver failure in humans and might be of special importance for the study of the mechanisms contributing to the pathogenesis of end-stage chronic liver disease or its implications on other organs. Conclusion: IKK2-mediated signaling in hepatocytes protects the liver from damage under conditions of chronic inflammatory cholestasis and prevents the development of severe fibrosis and liver failure
The bile acid receptor TGR5 and cholestasis
During liver injury and cholestasis, the mechanisms allowing the organ to protect itself with the aim of maintaining biliary homeostasis are not completely understood. Central to their biological roles, bile acids (BAs) and their receptors constitute a signaling network with multiple molecular and cellular impacts on both liver repair and protection from BA overload. BA signal through nuclear [mainly farnesoid X receptor (FXR)] and membrane [mainly G protein-coupled BA receptor 1 (GPBAR-1), aka Takeda G protein-coupled receptor 5 (TGR5)] receptors, in which activation elicits a wide array of biological responses. So far, most of the studies have been focused on FXR signaling as hepato-protective, TGR5 being less explored to this regard. While the liver faces massive and potentially harmful BA overload during cholestasis, it is crucial to understand that BAs induce also protective responses contributing not only to reduce the inflammatory burden, but also to spare liver cells and their repair capacities. Based on the available literature, the TGR5 BA receptor protects the liver in the cholestatic context and counteracts BA overload with the aim of restoring biliary homeostasis mainly through the control of inflammatory processes, biliary epithelial barrier permeability, and BA pool composition. Mouse experimental models of cholestasis reveal that the lack of TGR5 was associated with exacerbated inflammation and necrosis, leaky biliary epithelium, and excessive BA pool hydrophobicity, resulting in biliary cell and parenchymal insult, and compromising optimal restoration of biliary homeostasis and liver repair. There are thus widely opened translational perspectives with the aim of targeting TGR5-related signaling or biological responses to trigger protection of the cholestatic liver
Ca2+-mobilizing hormones induce sequentially ordered Ca2+ signals in multicellular systems of rat hepatocytes
Participation of 5-lipoxygenase and LTB4 in liver regeneration after partial hepatectomy
Regeneration is the unmatched liver ability for recovering its functional mass after tissue lost. Leukotrienes (LT) are a family of eicosanoids with the capacity of signaling to promote proliferation. We analyzed the impact of blocking LT synthesis during liver regeneration after partial hepatectomy (PH). Male Wistar rats were subjected to two-third PH and treated with zileuton, a specific inhibitor of 5-lipoxygenase (5-LOX). Our first find was a significant increment of intrahepatic LTB4 during the first hour after PH together with an increase in 5-LOX expression. Zileuton reduced hepatic LTB4 levels at the moment of hepatectomy and also inhibited the increase in hepatic LTB4. This inhibition produced a delay in liver proliferation as seen by decreased PCNA and cyclin D1 nuclear expression 24 h post-PH. Results also showed that hepatic LTB4 diminution by zileuton was associated with a decrease in NF-ÄžB activity. Additionally, decreased hepatic LTB4 levels by zileuton affected the recruitment of neutrophils and macrophages. Non-parenchymal cells (NPCs) from zileuton-treated PH-rats displayed higher apoptosis than NPCs from PH control rats. In conclusion, the present work provides evidences that 5-LOX activation and its product LTB4 are involved in the initial signaling events for liver regeneration after PH and the pharmacological inhibition of this enzyme can delay the initial time course of the phenomenon.Fil: Lorenzetti, Florencia. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FisiologĂa Experimental. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Instituto de FisiologĂa Experimental; ArgentinaFil: Vera, Marina Cecilia. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FisiologĂa Experimental. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Instituto de FisiologĂa Experimental; ArgentinaFil: Ceballos Mancini, MarĂa Paula. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FisiologĂa Experimental. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Instituto de FisiologĂa Experimental; ArgentinaFil: Ronco, Maria Teresa. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FisiologĂa Experimental. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Instituto de FisiologĂa Experimental; ArgentinaFil: Pisani, Gerardo Bruno. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Departamento de Ciencias FisiolĂłgicas. Ărea MorfologĂa; ArgentinaFil: Monti, Juan Alberto. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FisiologĂa Experimental. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Instituto de FisiologĂa Experimental; ArgentinaFil: Lucci, Alvaro. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FisiologĂa Experimental. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Instituto de FisiologĂa Experimental; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Departamento de Ciencias FisiolĂłgicas. Ărea MorfologĂa; ArgentinaFil: Comanzo, Carla Gabriela. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FisiologĂa Experimental. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Instituto de FisiologĂa Experimental; ArgentinaFil: Tordjmann, Thierry. UniversitĂ© Paris-Saclay; Francia. Institut National de la SantĂ© et de la Recherche MĂ©dicale; FranciaFil: Carrillo, MarĂa Cristina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FisiologĂa Experimental. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Instituto de FisiologĂa Experimental; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Departamento de Ciencias FisiolĂłgicas. Ărea MorfologĂa; ArgentinaFil: Quiroga, Ariel Dario. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FisiologĂa Experimental. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Instituto de FisiologĂa Experimental; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Departamento de Ciencias FisiolĂłgicas. Ărea MorfologĂa; Argentina. Universidad Abierta Interamericana. Facultad de Medicina. Centro de Altos Estudios en Ciencias de la Salud; ArgentinaFil: Alvarez, MarĂa de LujĂĄn. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FisiologĂa Experimental. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Instituto de FisiologĂa Experimental; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Departamento de Ciencias FisiolĂłgicas. Ărea MorfologĂa; Argentina. Universidad Abierta Interamericana. Facultad de Medicina. Centro de Altos Estudios en Ciencias de la Salud; Argentin
Cell to Cell Communication in Response to Mechanical Stress via Bilateral Release of Atp and Utp in Polarized Epithelia
Airway epithelia are positioned at the interface between the body and the environment, and generate complex signaling responses to inhaled toxins and other stresses. Luminal mechanical stimulation of airway epithelial cells produces a propagating wave of elevated intracellular Ca2+ that coordinates components of the integrated epithelial stress response. In polarized airway epithelia, this response has been attributed to IP3 permeation through gap junctions. Using a combination of approaches, including enzymes that destroy extracellular nucleotides, purinergic receptor desensitization, and airway cells deficient in purinoceptors, we demonstrated that Ca2+ waves induced by luminal mechanical stimulation in polarized airway epithelia were initiated by the release of the 5âČ nucleotides, ATP and UTP, across both apical and basolateral membranes. The nucleotides released into the extracellular compartment interacted with purinoceptors at both membranes to trigger Ca2+ mobilization. Physiologically, apical membrane nucleotide-release coordinates airway mucociliary clearance responses (mucin and salt, water secretion, increased ciliary beat frequency), whereas basolateral release constitutes a paracrine mechanism by which mechanical stresses signal adjacent cells not only within the epithelium, but other cell types (nerves, inflammatory cells) in the submucosa. Nucleotide-release ipsilateral and contralateral to the surface stimulated constitutes a unique mechanism by which epithelia coordinate local and distant airway defense responses to mechanical stimuli
Cell to Cell Communication in Response to Mechanical Stress via Bilateral Release of Atp and Utp in Polarized Epithelia
RÎle de la signalisation purinergique au cours de la régénération du foie chez la souris (étude des récepteurs P2X4 et P2X7)
Objectif : La régénération hépatique est un processus complexe qui met en jeu de nombreux signaux régulateurs endocrines, paracrines, autocrines et nerveux. L ATP extracellulaire et plus généralement la signalisation purinergique, ont été décrits comme ayant un rÎle dans la survie et la prolifération cellulaires ainsi que dans les processus inflammatoires et sécrétoires. Le laboratoire a rapporté antérieurement que l ATP extracellulaire contribuait à la régénération du foie chez le rat. L objectif de ce travail était d étudier le rÎle des récepteurs ionotropiques P2X4 et P2X7 au cours de la régénération hépatique aprÚs hépatectomie des deux tiers (Hx) chez la souris. Résultats : Les récepteurs P2X4 et P2X7 étaient fortement exprimés par les cellules de Kupffer et par les hépatocytes avec, pour le récepteur P2X4, un renforcement canaliculaire et sous-canaliculaire. AprÚs Hx, un retard de régénération par rapport aux souris WT (restauration de la masse du foie, expression protéique de la cycline D1 et du PCNA, entrée en mitose des hépatocytes), ainsi que des lésions de nécrose hépatique et une cholestase prolongée étaient observés chez les souris P2X4 KO mais pas chez les P2X7 KO. La réponse adaptative hépatocytaire à la surcharge en acides biliaires aprÚs Hx n était pas altérée chez les souris P2X4 KO (vs WT) (régulation transcritpionnelle de CYP7a1, NTCP, et OSTb), alors que l adaptation du flux biliaire et de la sécrétion d HCO3- dans la bile était anormale. Enfin, une réponse inflammatoire exacerbée était observée aprÚs Hx chez les souris P2X4 KO, (ARNm et concentrations plasmatiques de IL-1b, TNF-a et IL-6) par rapport aux souris WT. In vitro, le récepteur P2X4 n avait pas d impact significatif sur la prolifération hépatocytaire, ni sur la réponse au LPS (lipopolysaccharide) ou à l ATP des macrophages péritonéaux (MP). Conclusion : Pendant la régénération du foie, le récepteur P2X4 contribuerait au contrÎle de l homéostasie bilaire et de la réponse inflammatoire, deux éléments dont la régulation est essentielle au bon déroulement du processus de régénération. Les mécanismes par lesquels le récepteur P2X4 régule ces différents processus restent à déterminer.Background : Liver regeneration is a complex process during which various endocrine, paracrine, autocrine and nervous factors play important roles. Extracellular ATP and more generally purinergic signalling has been described to regulate cell survival and proliferation, as well as inflammatory processes. We previously reported that extracellular ATP contributed to liver regeneration in the rat. In this work, we analysed the involvement of the membrane ionotropic P2X4 and P2X7 purinergic receptors during liver regeneration after a two-third partial hepatectomy (PH) in mice. Results : P2X4 and P2X7 receptors were highly expressed in Kupffer cells, and in hepatocytes with reinforcement in the sub-canalicular and canalicular areas for P2X4 receptor. After PH, there was a delay in P2X4 KO as compared to WT mice, in liver mass restoration, cyclin D1 and PCNA expression, and mitotic activity. Post-PH hepatocyte necrosis (periportal focal bile infarcts ) and prolonged cholestasis were observed in P2X4-KO mice, but neither WT, nor P2X7 KO mice. Adaptive response to post-PH cholestasis (CYP7a1, NTCP and OSTb mRNA regulation) was similar in WT and P2X4-KO livers. In P2X4 KO mice after PH, as compared with WT, smaller increase in bile flow and HCO3- biliary output were observed. Early mRNA induction, as well as plasma concentration rise in cytokines (IL1 b, TNFa and IL6) were greater in P2X4-KO than WT mice after PH. In vitro, the P2X4 receptor didn t impact significantly hepatocyte proliferation, nor peritoneal macrophages (PM) inflammatory reponse to LPS (lipopolysaccharide) or ATP. Conclusions : During liver regeneration, P2X4 may contribute to the complex control of hepatocyte proliferation through the regulation of biliary homeostasis and inflammation. Mechanisms underlying P2X4 involvement in those processes still remain to be definedPARIS-BIUSJ-Biologie recherche (751052107) / SudocSudocFranceF
Ca2+ et régénération du foie (impact de la signalisation calcique intracellulaire sur la prolifération hépatocytaire)
LE FOIE possÚde une capacité exceptionnelle à régénérer à la suite d une lésion induite soit chirurgicalement soit par des agents toxiques. Parmi les agonistes impliqués dans le processus régénératif, nombreux sont ceux qui mobilisent le calcium (Ca2+) intracellulaire, sans que l impact physiologique de cette voie de signalisation soit déterminé. Pour l étudier, nous avons interféré in vivo avec la signalisation calcique par transfert de gÚne grùce à un vecteur adénoviral. La parvalbumine (PV), une protéine tamponnant le Ca2+, a été adressée sélectivement dans le cytosol ou le noyau des hépatocytes, et la régénération du foie a été analysée aprÚs hépatectomie partielle (Hx) chez le rat. Nous avons ainsi mis en évidence un ralentissement de la régénération hépatique chez les animaux exprimant la PV cytosolique (PV-NES-DsR). En effet, nous avons observé, aprÚs Hx, un retard dans la prise de poids du foie ainsi que dans la progression des hépatocytes dans le cycle cellulaire. Ce retard était associé à une transcription altérée du gÚne précoce c-fos, fortement impliqué dans le démarrage du processus régénératif, ainsi que des gÚnes des cyclines E et A et la kinase associée cdk2. Nous avons également observé un retard d activation de la voie ERK 1/2, impliquée dans la prolifération hépatocytaire au cours de la régénération, et connue pour sa dépendance vis-à -vis du Ca2+. Une moindre activation de la réponse cytokinique a également été observée aprÚs Hx chez les animaux PV-NES-DsR, dont les mécanismes restent à préciser. Par ailleurs, nous avons observé in vitro, sur des cultures primaires d hépatocytes exprimant PV-NES-DsR, un retard de prolifération et mis en évidence une altération de la phosphorylation de CREB, un facteur de transcription activé par le Ca2+. Ces résultats nous indiquent que le calcium cytosolique régule de maniÚre positive la régénération hépatique. Des résultats préliminaires aprÚs expression nucléaire de la PV (PV-NLS-DsR) dans les hépatocytes, in vivo et in vitro, indiquent que le tamponnement du Ca2+ dans ce compartiment conduit à l apoptose des hépatocytes. L ensemble de ces données indiquent que la signalisation calcique contribue à réguler les processus de croissance et de survie hépatocytaire.PARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF
Régulation endocrine de la régénération hépatique chez le rat (implication physiologique de la vasopressine et remodelage de la signalisation calcique hépatocytaire)
PARIS-BIUSJ-ThĂšses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF
Calcium Signalling and Liver Regeneration
After partial hepatectomy (PH) the initial mass of the organ is restored through a complex network of cellular interactions that orchestrate both proliferative and hepatoprotective signalling cascades. Among agonists involved in this network many of them drive Ca2+ movements. During liver regeneration in the rat, hepatocyte cytosolic Ca2+ signalling has been shown on the one hand to be deeply remodelled and on the other hand to enhance progression of hepatocytes through the cell cycle. Mechanisms through which cytosolic Ca2+ signals impact on hepatocyte cell cycle early after PH are not completely understood, but at least they include regulation of immediate early gene transcription and ERK and CREB phosphorylation. In addition to cytosolic Ca2+, there is also evidence that mitochondrial Ca2+ and also nuclear Ca2+ may be critical for the regulation of liver regeneration. Finally, Ca2+ movements in hepatocytes, and possibly in other liver cells, not only impact hepatocyte progression in the cell cycle but more generally may regulate cellular homeostasis after PH
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