at the CNIC

Category: Publications (Page 1 of 5)

Cell identity and nucleo-mitochondrial genetic context modulate OXPHOS performance and determine somatic heteroplasmy dynamics

Ana Victoria Lechuga-Vieco, Ana Latorre-Pellicer, Iain G. Johnston, Gennaro Prota, Uzi Gileadi, Raquel Justo-Méndez, Rebeca Acín-Pérez, Raquel Martínez-de-Mena, Jose María Fernández-Toro, Daniel Jimenez-Blasco, Alfonso Mora, Jose A. Nicolás-Ávila, Demetrio J. Santiago, Silvia G. Priori, Juan Pedro Bolaños, Guadalupe Sabio, Luis Miguel Criado, Jesús Ruíz-Cabello, Vincenzo Cerundolo, Nick S. Jones, José Antonio Enríquez.

Heteroplasmy, multiple variants of mitochondrial DNA (mtDNA) in the same cytoplasm, may be naturally generated by mutations but is counteracted by a genetic mtDNA bottleneck during oocyte development.

Mitochondria (Image: Alfonso Mora).

Engineered heteroplasmic mice with nonpathological mtDNA variants reveal a nonrandom tissue-specific mtDNA segregation pattern, with few tissues that do not show segregation. The driving force for this dynamic complex pattern has remained unexplained for decades, challenging our understanding of this fundamental biological problem and hindering clinical planning for inherited diseases.

Here, we demonstrate that the nonrandom mtDNA segregation is an intracellular process based on organelle selection. This cell type–specific decision arises jointly from the impact of mtDNA haplotypes on the oxidative phosphorylation (OXPHOS) system and the cell metabolic requirements and is strongly sensitive to the nuclear context and to environmental cues.

JNK-mediated disruption of bile acid homeostasis promotes intrahepatic cholangiocarcinoma

Elisa Manieri, Cintia Folgueira, María Elena Rodríguez, Luis Leiva-Vega, Laura Esteban-Lafuente, Chaobo Chen, Francisco Javier Cubero, Tamera Barrett, Julie Cavanagh-Kyros, Davide Seruggia, Alejandro Rosell, Fátima Sanchez-Cabo, Manuel Jose Gómez, Maria J. Monte, Jose J. G. Marin, Roger J. Davis, Alfonso Mora & Guadalupe Sabio.

Obesity is associated with hepatic steatosis and activation of the cJun NH2-terminal kinase (JNK) stress-signaling pathway. Studies in mice demonstrate that JNK deficiency in the liver prevents the development of hepatic steatosis. This observation suggests that inhibition of JNK signaling may represent a possible treatment for hepatic steatosis. However, the long-term consequences of JNK inhibition are poorly understood.

Liver cholangiocarcinoma (Photo: Chaobo Chen).

Here we demonstrate that loss of JNK causes changes in cholesterol and bile acid metabolism that promote cholestasis, bile duct proliferation, and intrahepatic cholangiocarcinoma. We identify PPARα activation as the molecular mechanism that accounts for this phenotype .

Our analysis has important implications for the long-term use of JNK inhibitors for the treatment of obesity.

p38γ is essential for cell cycle progression and liver tumorigenesis

Antonia Tomás-Loba, Elisa Manieri, Bárbara González-Terán, Alfonso Mora, Luis Leiva-Vega, Ayelén M. Santamans, Rafael Romero-Becerra, Elena Rodríguez, Aránzazu Pintor-Chocano, Ferran Feixas, Juan Antonio López, Beatriz Caballero, Marianna Trakala, Óscar Blanco, Jorge L. Torres, Lourdes Hernández-Cosido, Valle Montalvo-Romeral, Nuria Matesanz, Marta Roche-Molina, Juan Antonio Bernal, Hannah Mischo, Marta León, Ainoa Caballero, Diego Miranda-Saavedra, Jesús Ruiz-Cabello, Yulia A. Nevzorova, Francisco Javier Cubero, Jerónimo Bravo, Jesús Vázquez, Marcos Malumbres, Miguel Marcos, Sílvia Osuna & Guadalupe Sabio.

The cell cycle is a tightly regulated process that is controlled by the conserved cyclin-dependent kinase (CDK)–cyclin protein complex. However, control of the G0-to-G1 transition is not completely understood.

Mitosis in liver
Mitosis in hepatocytes (Photo: Alfonso Mora/CNIC).

Here we demonstrate that p38 MAPK gamma (p38γ) acts as a CDK-like kinase and thus cooperates with CDKs, regulating entry into the cell cycle. p38γ shares high sequence homology, inhibition sensitivity and substrate specificity with CDK family members. In mouse hepatocytes, p38γ induces proliferation after partial hepatectomy by promoting the phosphorylation of retinoblastoma tumour suppressor protein at known CDK target residues.

Lack of p38γ or treatment with the p38γ inhibitor pirfenidone protects against the chemically induced formation of liver tumours. Furthermore, biopsies of human hepatocellular carcinoma show high expression of p38γ, suggesting that p38γ could be a therapeutic target in the treatment of this disease.

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