Data of ureagenesis from ammonia, glutamine and alanine, and mitochondrial aquaporin-8 expression in thioacetamide-treated hepatocytes

We present data about the synthesis of urea from different substrates, i.e., free ammonia, glutamine and alanine in primary cultured rat hepatocytes treated or untreated with the model hepatotoxic agent thioacetamide (TAA). We also provide data about the expression of mitochondrial aquaporin-8 (mtAQP8), a hepatocyte channel protein which facilitates ammonia diffusion into mitochondria to supply the urea cycle. Ammonia-derived ureagenesis was significantly inhibited by about 30% while that from the both amino acids resulted unaffected in TAA-treated hepatocytes. Protein expression of mtAQP8 was decreased by about 80% after TAA treatment. These data can be useful for the understanding of the mechanisms of drug-induced hepatic dysfunction.Fil: Capiglioni, Alejo Matías. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Alvarez, María de Luján. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Marinelli, Raul Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; Argentin

Mitochondrial aquaporin-8 is involved in SREBP-controlled hepatocyte cholesterol biosynthesis

Cholesterol, via sterol regulatory element-binding protein (SREBP) transcription factors, activates or represses genes involved in its hepatic biosynthetic pathway, and also modulates the expression of hepatocyte mitochondrial aquaporin-8 (mtAQP8), a channel that can function as peroxiporin by facilitating the transmembrane diffusion of H2O2. Here we tested the hypothesis that mtAQP8 is involved in the SREBP-mediated regulation of hepatocyte cholesterol biosynthesis. Using human hepatocyte-derived Huh-7 cells and primary rat hepatocytes, we found that mtAQP8 knockdown significantly downregulated de novo cholesterol synthesis as well as protein expressions of SREBP-2 and its target gene, a rate-limiting enzyme in cholesterol synthesis 3-Hydroxy-3-Methylglutaryl-CoA Reductase (HMGCR). In contrast, adenovirus-mediated human AQP8 mitochondrial expression significantly increased de novo cholesterol synthesis and protein expressions of SREBP-2 and HMGCR. In mtAQP8-overexpressed hepatocytes, mitochondrial H2O2 release was found to be increased; and a mitochondria-targeted antioxidant prevented the upregulation of mitochondrial H2O2 release and that of cholesterol synthesis. Our results suggest that peroxiporin mtAQP8 plays a role in the SREBP-controlled hepatocyte cholesterogenesis, a finding that might be relevant to cholesterol-related metabolic disorders.Fil: Danielli, Mauro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Marrone, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Capiglioni, Alejo Matías. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Marinelli, Raul Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; Argentin

Further evidence for the involvement of mitochondrial aquaporin-8 in hepatocyte lipid synthesis

We recently provided evidence suggesting that mitochondrial aquaporin-8 (mtAQP8), a channel protein able to conduct H2O2, is involved in the modulation of hepatocyte cholesterogenesis. To expand that study, we cultured human hepatocyte-derived Huh-7 cells in medium with lipoprotein-deficient serum (LPDS) to induce the de novo synthesis of cholesterol and fatty acids. We found that LPDS induced mtAQP8 expression and that AQP8 gene silencing significantly down-regulated the LPDS-induced synthesis of cholesterol and fatty acids as well as the expression of the corresponding key biosynthetic enzymes, 3-hydroxy-3-methylglutaryl-CoA reductase and fatty acid synthase. Our data further support a regulatory role of mtAQP8 in hepatocyte lipid homeostasis.Fil: Danielli, Mauro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Capiglioni, Alejo Matías. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Marrone, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Marinelli, Raul Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; Argentin

Aquaporin gene transfer for hepatocellular cholestasis

Bile secretion by hepatocytes is an osmotic process. The output of bile salts and other organic anions (e.g. glutathione), through the bile salt transporter BSEP/ABCB11 and the organic anion transporter MRP2/ABCC2, respectively, are considered to be the major osmotic driving forces for water secretion into bile canaliculi mainly via aquaporin-8 (AQP8) channels. The down-regulated canalicular expression of these key solute transporters and AQP8 would be a primary event in the establishment of hepatocellular cholestasis. Recent studies in animal models of hepatocellular cholestasis show that the hepatic delivery of AdhAQP1, an adenovector encoding for the archetypical water channel human aquaporin-1 (hAQP1), improves bile secretion and restores to normal the elevated serum bile salt levels. AdhAQP1-transduced hepatocytes show that the canalicularly-expressed hAQP1 not only enhances osmotic membrane water permeability but also induces the transport activities of BSEP/ABCB11 and MRP2/ABCC2 by redistribution in canalicular cholesterol-rich microdomains likely through interactions with the cholesterol-binding protein caveolin-1. Thus, the hepatic gene transfer of hAQP1 improves the bile secretory failure in hepatocellular cholestasis by increasing both biliary output and choleretic efficiency of key osmotic solutes, such as, bile salts and glutathione. The study of hepatocyte aquaporins has provided new insights into the mechanisms of bile formation and cholestasis, and may lead to innovative treatments for cholestatic liver diseases.Fil: Marrone, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Danielli, Mauro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Gaspari, César Ismael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Capiglioni, Alejo Matías. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Marinelli, Raul Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; Argentin

Hepatic glycerol metabolism is early reprogrammed in rat liver cancer development

Evidence shows that oral glycerol supplementation during the early stages of rat liver cancer reduces the growth of preneoplastic lesions. Besides, human hepatocellular carcinoma (HCC) cells display decreased expression of glycerol channel aquaporin 9 (AQP9) and also diminished glycerol-3-phosphate (G3P) content. According to this, we analyzed glycerol metabolism during the initial stages of rat liver carcinogenesis. Wistar rats were subjected to a 2-phase model of hepatocarcinogenesis (initiated-promoted, IP group) or left untreated (control, C group). Different features of glycerol metabolism were compared between both groups. IP animals showed increased plasma free glycerol levels and liver AQP9 protein expression. Also, IP rats showed increased glycerol kinase (GK) and glycerol-3-phosphate dehydrogenase (GPDH) hepatic activities. Gluconeogenesis from glycerol both in vivo and in isolated perfused liver was higher in rats having liver preneoplasia. Nevertheless, preneoplastic foci notably reduced AQP9 and GK protein expressions, displaying a reduced ability to import glycerol and to convert it into G3P, as a way to preserve preneoplastic hepatocytes from the deleterious effect of G3P. In conclusion, the metabolic shift that takes place in the initial stages of liver cancer development comprises an increased hepatic utilization of glycerol for gluconeogenesis. Enhanced glucose production from glycerol is mostly carried out by the surrounding non-preneoplastic tissue and can be used as an energy source for the early transformed liver cells.Fil: Lorenzetti, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Capiglioni, Alejo Matías. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Marinelli, Raul Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Carrillo, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Alvarez, María de Luján. Universidad Abierta Interamericana; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; Argentin

Enhanced ammonia detoxification to urea in hepatocytes transduced with human aquaporin-8 gene

Hepatic ammonia detoxification to urea is critical for the prevention of hyperammonemia and neurological damage. Hepatocyte mitochondrial aquaporin-8 (AQP8) channels have been involved in ammonia-derived ureagenesis. Herein, we studied whether the adenoviral gene transfer of human AQP8 (hAQP8) to hepatocyte mitochondria enhances ammonia conversion to urea. Using primary cultured rat hepatocytes, we first confirmed the mitochondrial expression of hAQP8 and then, using unlabeled or 15N-labeled ammonia, we demonstrated that the urea synthesis was significantly enhanced in hAQP8-transduced hepatocytes. Studies using isolated hAQP8-expressing mitochondria also showed an increased ammonia metabolism. hAQP8 transduction was able to recover the impaired ammonia-derived ureagenesis in hepatotoxin-treated hepatocytes. Our data suggest that mitochondrially-expressed hAQP8 enhances and improves hepatocyte ammonia conversion to urea, a finding with potential therapeutic implications for liver disease with impaired ammonia detoxification.Fil: Capiglioni, Alejo Matías. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Müller, Gabriela Leticia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Marrone, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Alvarez, María de Luján. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; ArgentinaFil: Marinelli, Raul Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; Argentin