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Tag: p38γ (Page 1 of 5)

MKK6 deficiency promotes cardiac dysfunction through MKK3-p38γ/δ-mTOR hyperactivation

Rafael Romero-Becerra, Alfonso Mora, Elisa Manieri, Ivana Nikolic, Ayelén Melina Santamans, Valle Montalvo-Romeral, Francisco Miguel Cruz, Elena Rodríguez, Marta León, Luis Leiva-Vega, Laura Sanz, Víctor Bondía, David Filgueiras-Rama, Luis Jesús Jiménez-Borreguero, José Jalife, Barbara Gonzalez-Teran & Guadalupe Sabio.

Stress-activated p38 kinases control a plethora of functions, and their dysregulation has been linked to the development of steatosis, obesity, immune disorders, and cancer. Therefore, they have been identified as potential targets for novel therapeutic strategies. There are four p38 family members (p38α, p38β, p38γ, and p38δ) that are activated by MKK3 and MKK6.

Cardiac hypertrophy under the microscope.
Cardiac hypertrophy in a heart lacking MKK6 (Image: Bárbara González-Terán).

Here, we demonstrate that lack of MKK6 reduces the lifespan in mice. Longitudinal study of cardiac function in MKK6 KO mice showed that young mice develop cardiac hypertrophy which progresses to cardiac dilatation and fibrosis with age. Mechanistically, lack of MKK6 blunts p38α activation while causing MKK3-p38γ/δ hyperphosphorylation and increased mammalian target of rapamycin (mTOR) signaling, resulting in cardiac hypertrophy. Cardiac hypertrophy in MKK6 KO mice is reverted by knocking out either p38γ or p38δ or by inhibiting the mTOR pathway with rapamycin.

In conclusion, we have identified a key role for the MKK3/6-p38γ/δ pathway in the development of cardiac hypertrophy, which has important implications for the clinical use of p38α inhibitors in the long-term treatment since they might result in cardiotoxicity.

p38γ and p38δ regulate postnatal cardiac metabolism through glycogen synthase 1

Ayelén M. Santamans, Valle Montalvo-Romeral, Alfonso Mora, Juan Antonio Lopez, Francisco González-Romero, Daniel Jimenez-Blasco, Elena Rodríguez, Aránzazu Pintor-Chocano, Cristina Casanueva-Benítez, Rebeca Acín-Pérez, Luis Leiva-Vega, Jordi Duran, Joan J. Guinovart, Jesús Jiménez-Borreguero, José Antonio Enríquez, María Villlalba-Orero, Juan P. Bolaños, Patricia Aspichueta, Jesús Vázquez, Bárbara González-Terán, Guadalupe Sabio.

During the first weeks of postnatal heart development, cardiomyocytes undergo a major adaptive metabolic shift from glycolytic energy production to fatty acid oxidation. This metabolic change is contemporaneous to the up-regulation and activation of the p38γ and p38δ stress-activated protein kinases in the heart.

Cardiac fibrosis (Image: Ayelén Santamans/CNIC).

We demonstrate that p38γ/δ contribute to the early postnatal cardiac metabolic switch through inhibitory phosphorylation of glycogen synthase 1 (GYS1) and glycogen metabolism inactivation. Premature induction of p38γ/δ activation in cardiomyocytes of newborn mice results in an early GYS1 phosphorylation and inhibition of cardiac glycogen production, triggering an early metabolic shift that induces a deficit in cardiomyocyte fuel supply, leading to whole-body metabolic deregulation and maladaptive cardiac pathogenesis. Notably, the adverse effects of forced premature cardiac p38γ/δ activation in neonate mice are prevented by maternal diet supplementation of fatty acids during pregnancy and lactation.

These results suggest that diet interventions have a potential for treating human cardiac genetic diseases that affect heart metabolism.

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