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Tag: liver (Page 2 of 10)

Mitochondrial bioenergetics boost macrophages activation promoting liver regeneration in metabolically compromised animals

Naroa Goikoetxea-Usandizaga, Marina Serrano-Maciá, Teresa C. Delgado, Jorge Simón, David Fernández Ramos, Diego Barriales, Maria E. Cornide, Mónica Jiménez, Marina Pérez-Redondo, Sofia Lachiondo-Ortega, Rubén Rodríguez-Agudo, Maider Bizkarguenaga, Juan Diego Zalamea, Samuel T. Pasco, Daniel Caballero-Díaz, Benedetta Alfano, Miren Bravo, Irene González-Recio, Maria Mercado-Gómez, Clàudia Gil-Pitarch, Jon Mabe, Jordi Gracia-Sancho, Leticia Abecia, Óscar Lorenzo, Paloma Martín-Sanz, Nicola G. A. Abrescia, Guadalupe Sabio, Mercedes Rincón, Juan Anguita, Eduardo Miñambres, César Martín, Marina Berenguer, Isabel Fabregat, Marta Casado, Carmen Peralta, Marta Varela-Rey & María Luz Martínez-Chantar.

BACKGROUND & AIMS: Hepatic ischemia-reperfusion injury (IRI) is the leading cause of early post-transplantation organ failure, as mitochondrial respiration and ATP production are affected. Shortage of donors has extended liver donor criteria, including aged or steatotic livers, which are more susceptible to IRI. Given the lack of an effective treatment and the extensive transplantation waitlist, we aimed at characterizing the effects of an accelerated mitochondrial activity by silencing Methylation-controlled J protein (MCJ) in three pre-clinical models of IRI and liver regeneration, focusing on metabolically compromised animal models.

Hepatic uptake of 18F-fluorodeoxyglucose (Image: Alfonso Mora).

APPROACH & RESULTS: Wt, MCJ KO and Mcj silenced Wt mice were subjected to 70% Partial hepatectomy (Phx), prolonged IRI and 70% Phx with IRI. Old and mice with metabolic syndrome were also subjected to these procedures. Expression of MCJ, an endogenous negative regulator of mitochondrial respiration, increases in pre-clinical models of Phx with or without vascular occlusion, and in donors’ livers. Mice lacking MCJ initiate liver regeneration 12h faster than WT, show reduced ischemic injury and increased survival. MCJ knockdown enables a mitochondrial adaptation that restores the bioenergetic supply for enhanced regeneration and prevents cell death after IRI. Mechanistically, increased ATP secretion facilitates the early activation of kupffer cells and production of TNF, IL-6 and HB-EGF accelerating the priming phase and the progression through G1/S transition during liver regeneration. Therapeutic silencing of MCJ in 15-month-old mice and in mice fed with a high fat-high fructose diet for 12 weeks improves mitochondrial respiration, reduces steatosis and overcomes regenerative limitations.

CONCLUSIONS: Boosting mitochondrial activity by silencing MCJ could pave the way for a novel protective approach after major liver resection or IRI, specially in metabolically compromised, IRI susceptible organs.

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.

Circadian clock and liver cancer

María Crespo, Magdalena Leiva & Guadalupe Sabio.

Circadian clocks control several homeostatic processes in mammals through internal molecular mechanisms. Chronic perturbation of circadian rhythms is associated with metabolic diseases and increased cancer risk, including liver cancer.

The mammalian circadian clock

The hepatic physiology follows a daily rhythm, driven by clock genes that control the expression of several proteins involved in distinct metabolic pathways. Alteration of the liver clock results in metabolic disorders, such as non-alcoholic fatty liver diseases (NAFLD) and impaired glucose metabolism, that can trigger the activation of oncogenic pathways, inducing spontaneous hepatocarcinoma (HCC).

In this review, we provide an overview of the role of the liver clock in the metabolic and oncogenic changes that lead to HCC and discuss new potentially useful targets for prevention and management of HCC.

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