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Tag: kinases (Page 1 of 4)

Stress kinases in the development of liver steatosis and hepatocellular carcinoma

Beatriz Cicuéndez, Irene Ruiz-Garrido, Alfonso Mora & Guadalupe Sabio.

Non-alcoholic fatty liver disease (NAFLD) is an important component of metabolic syndrome and one of the most prevalent liver diseases worldwide. This disorder is closely linked to hepatic insulin resistance, lipotoxicity, and inflammation.

p38 pathway during liver steatosis
p38 pathway during liver steatosis.

Although the mechanisms that cause steatosis and chronic liver injury in NAFLD remain unclear, a key component of this process is the activation of stress-activated kinases (SAPKs), including p38 and JNK in the liver and immune system.

This review summarizes findings which indicate that the dysregulation of stress kinases plays a fundamental role in the development of steatosis and are important players in inducing liver fibrosis. To avoid the development of steatohepatitis and liver cancer, SAPK activity must be tightly regulated not only in the hepatocytes but also in other tissues, including cells of the immune system. Possible cellular mechanisms of SAPK actions are discussed.

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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