at the CNIC

Tag: p53

O-GlcNAcylated p53 in the liver modulates hepatic glucose production

Maria J. Gonzalez-Rellan, Marcos F. Fondevila, Uxia Fernandez, Amaia Rodríguez, Marta Varela-Rey, Christelle Veyrat-Durebex, Samuel Seoane, Ganeko Bernardo, Fernando Lopitz-Otsoa, David Fernández-Ramos, Jon Bilbao, Cristina Iglesias, Eva Novoa, Cristina Ameneiro, Ana Senra, Daniel Beiroa, Juan Cuñarro, Maria DP Chantada-Vazquez, Maria Garcia-Vence, Susana B. Bravo, Natalia Da Silva Lima, Begoña Porteiro, Carmen Carneiro, Anxo Vidal, Sulay Tovar, Timo D. Müller, Johan Ferno, Diana Guallar, Miguel Fidalgo, Guadalupe Sabio, Stephan Herzig, Won Ho Yang, Jin Won Cho, Maria Luz Martinez-Chantar, Roman Perez-Fernandez, Miguel López, Carlos Dieguez, Jose M. Mato, Oscar Millet, Roberto Coppari, Ashwin Woodhoo, Gema Fruhbeck & Ruben Nogueiras.

p53 regulates several signaling pathways to maintain the metabolic homeostasis of cells and modulates the cellular response to stress. Deficiency or excess of nutrients causes cellular metabolic stress, and we hypothesized that p53 could be linked to glucose maintenance.

Pyruvate tolerance test.

We show here that upon starvation hepatic p53 is stabilized by O-GlcNAcylation and plays an essential role in the physiological regulation of glucose homeostasis. More specifically, p53 binds to PCK1 promoter and regulates its transcriptional activation, thereby controlling hepatic glucose production. Mice lacking p53 in the liver show a reduced gluconeogenic response during calorie restriction. Glucagon, adrenaline and glucocorticoids augment protein levels of p53, and administration of these hormones to p53 deficient human hepatocytes and to liver-specific p53 deficient mice fails to increase glucose levels.

Moreover, insulin decreases p53 levels, and over-expression of p53 impairs insulin sensitivity. Finally, protein levels of p53, as well as genes responsible of O-GlcNAcylation are elevated in the liver of type 2 diabetic patients and positively correlate with glucose and HOMA-IR.

Overall these results indicate that the O-GlcNAcylation of p53 plays an unsuspected key role regulating in vivo glucose homeostasis.

Pharmacological stimulation of p53 with low-dose doxorubicin ameliorates diet-induced nonalcoholic steatosis and steatohepatitis

Begoña Porteiro, Marcos F. Fondevila, Xabier Buque, Maria J. Gonzalez-Rellan, Uxia Fernandez, Alfonso Mora, Daniel Beiroa, Ana, Senra, Rosalia Gallego, Johan Fernø, Miguel López, Guadalupe Sabio, Carlos Dieguez, Patricia Aspichueta & Rubén Nogueiras.

Recent reports have implicated the p53 tumor suppressor in the regulation of lipid metabolism. We hypothesized that the pharmacological activation of p53 with low-dose doxorubicin, which is widely used to treat several types of cancer, may have beneficial effects on nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH).

Hematoxylin&eosin and oil red O staining of liver sections.

We used long-term pharmacological activation of p53 by i.p. or oral administration of low-dose doxorubicin in different animal models of NAFLD (high fat diet containing 45% and 60% kcal fat) and NASH (methionine- and choline-deficient diet and choline deficiency combined with high fat diet). We also administered doxorubicin in mice lacking p53 in the liver and in two human hepatic cells lines (HepG2 and THLE2).

The attenuation of liver damage was accompanied by the stimulation of fatty acid oxidation and decrease of lipogenesis, inflammation, and ER stress. The effects of doxorubicin were abrogated in mice with liver-specific ablation of p53. Finally, the effects of doxorubicin on lipid metabolism found in animal models were also present in two human hepatic cells lines, in which the drug stimulated fatty acid oxidation and inhibited de novo lipogenesis at doses that did not cause changes in apoptosis or cell viability.

These data provide new evidence for targeting p53 as a strategy to treat liver disease

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