Sabio lab

at the CNIC

Category: Publications

Hepatic p63 regulates steatosis via IKKβ/ER stress

Begoña Porteiro, Marcos F. Fondevila, Teresa C. Delgado, Cristina Iglesias, Monica Imbernon, Paula Iruzubieta, Javier Crespo, Amaia Zabala-Letona, Johan Fernø, Bárbara González-Terán, Nuria Matesanz, Lourdes Hernández-Cosido, Miguel Marcos, Sulay Tovar, Anxo Vidal, Julia Sánchez-Ceinos, Maria M. Malagon, Celia Pombo, Juan Zalvide, Arkaitz Carracedo, Xabier Buque, Carlos Dieguez, Guadalupe Sabio, Miguel López, Patricia Aspichueta, María L. Martínez-Chantar & Ruben Nogueiras.

Pathway proposed to modulate lipid metabolism in liverp53 family members control several metabolic and cellular functions. The p53 ortholog p63 modulates cellular adaptations to stress and has a major role in cell maintenance and proliferation.

Here we show that p63 regulates hepatic lipid metabolism. Mice with liver-specific p53 deletion develop steatosis and show increased levels of p63. Down-regulation of p63 attenuates liver steatosis in p53 knockout mice and in diet-induced obese mice, whereas the activation of p63 induces lipid accumulation. Hepatic overexpression of N-terminal transactivation domain TAp63 induces liver steatosis through IKKβ activation and the induction of ER stress, the inhibition of which rescues the liver functions. Expression of TAp63, IKKβ and XBP1s is also increased in livers of obese patients with NAFLD. In cultured human hepatocytes, TAp63 inhibition protects against oleic acid-induced lipid accumulation, whereas TAp63 overexpression promotes lipid storage, an effect reversible by IKKβ silencing.

Our findings indicate an unexpected role of the p63/IKKβ/ER stress pathway in lipid metabolism and liver disease.


p38γ and δ promote heart hypertrophy by targeting the mTOR-inhibitory protein DEPTOR for degradation

Bárbara González-Terán, Juan Antonio López, Elena Rodríguez, Luis Leiva, Sara Martínez-Martínez, Juan Antonio Bernal, Luis Jesús Jiménez-Borreguero, Juan Miguel Redondo, Jesús Vazquez & Guadalupe Sabio.

heart

Disrupted organ growth leads to disease development. Hypertrophy underlies postnatal heart growth and is triggered after stress, but the molecular mechanisms involved in these processes are largely unknown.

Here we show that cardiac activation of p38γ and p38δ increases during postnatal development and by hypertrophy-inducing stimuli. p38γ/δ promote cardiac hypertrophy by phosphorylating the mTORC1 and mTORC2 inhibitor DEPTOR, which leads to its degradation and mTOR activation. Hearts from mice lacking one or both kinases are below normal size, have high levels of DEPTOR, low activity of the mTOR pathway and reduced protein synthesis. The phenotype of p38γ−/− mice is reverted by overactivation of mTOR with amino acids, shRNA-mediated knockdown of Deptor, or cardiomyocyte overexpression of active p38γ and p38δ. Moreover, in WT mice, heart weight is reduced by cardiac overexpression of DEPTOR.

Our results demonstrate that p38γ/δ control heart growth by modulating mTOR pathway through DEPTOR phosphorylation and subsequent degradation.


© 2017 Sabio lab

Crafted with love by ¡Cuánta Ciencia! using Anders Norén´s theme HemingwayUp ↑