Sabio lab

at the CNIC

Tag: obesity (page 2 of 7)

p107 deficiency increases energy expenditure by inducing brown‐fat thermogenesis and browning of white adipose tissue

Juan Cunarro, Xabier Buque, Sabela Casado, Javier Lugilde, Anxo Vidal, Alfonso Mora, Guadalupe Sabio, Rubén Nogueiras, Patricia Aspichueta, Carlos Diéguez & Sulay Tovar.

The tumor suppressor p107, a pocket protein member of the retinoblastoma susceptibility protein family, plays an important role in the cell cycle and cellular adipocyte differentiation. Nonetheless, the mechanism by which it influences whole body energy homeostasis is unknown.

p107 during adipocyte differentiation

p107 is underexpressed in the stromal fraction (time 0) with the expression increasing during adipocyte differentiation (Image: Alfonso Mora).

The phenotype of p107 knockout (KO) mixed‐background C57BL6/129 mice phenotype is studied by focusing on the involvement of white and brown adipose tissue (WAT and BAT) in energy metabolism. It is shown that p107 KO mice are leaner and have high‐fat diet resistence. This phenomenon is explained by an increase of energy expenditure. The higher energy expenditure is caused by the activation of thermogenesis and may be mediated by both BAT and the browning of WAT. Consequently, it leads to the resistance of p107 KO mice to high‐fat diet effects, prevention of liver steatosis, and improvement of the lipid profile and glucose homeostasis.

These data allowed the unmasking of a mechanism by which a KO of p107 prevents diet‐induced obesity by increasing energy expenditure via increased thermogenesis in BAT and browning of WAT, indicating the relevance of p107 as a modulator of metabolic activity of both brown and white adipocytes. Therefore, it can be targeted for the development of new therapies to ameliorate the metabolic syndrome.

El frío activa un mecanismo para adelgazar, pero también puede hacer daño al corazón

Guadalupe Sabio asegura que «uno de los problemas a los que nos enfrentamos es cómo activar la grasa parda sin producir efectos secundarios en el corazón».

[read more in El País]

Regulation of browning and BAT activation by p38 pathway (Image: Ivana Nikolić).

p38α blocks brown adipose tissue thermogenesis through p38δ inhibition

Nuria Matesanz, Ivana Nikolić, Magdalena Leiva, Marta Pulgarín-Alfaro, Ayelén M. Santamans, Edgar Bernardo, Alfonso Mora, Leticia Herrera-Melle, Elena Rodríguez, Daniel Beiroa, Ainoa Caballero, Elena Martín-García, Rebeca Acín-Pérez, Lourdes Hernández-Cosido, Luis Leiva-Vega, Jorge L. Torres, Francisco Centeno, Angel R. Nebreda, José Antonio Enríquez, Rubén Nogueiras, Miguel Marcos & Guadalupe Sabio.

Adipose tissue has emerged as an important regulator of whole-body metabolism, and its capacity to dissipate energy in the form of heat has acquired a special relevance in recent years as potential treatment for obesity. In this context, the p38MAPK pathway has arisen as a key player in the thermogenic program because it is required for the activation of brown adipose tissue (BAT) thermogenesis and participates also in the transformation of white adipose tissue (WAT) into BAT-like depot called beige/brite tissue.

Regulation of browning and BAT activation by p38 pathway (Image: Ivana Nikolić).

Here, using mice that are deficient in p38α specifically in adipose tissue (p38αFab-KO), we unexpectedly found that lack of p38α protected against high-fat diet (HFD)-induced obesity. We also showed that p38αFab-KO mice presented higher energy expenditure due to increased BAT thermogenesis. Mechanistically, we found that lack of p38α resulted in the activation of the related protein kinase family member p38δ.

Our results showed that p38δ is activated in BAT by cold exposure, and lack of this kinase specifically in adipose tissue (p38δFab-KO) resulted in overweight together with reduced energy expenditure and lower body and skin surface temperature in the BAT region. These observations indicate that p38α probably blocks BAT thermogenesis through p38δ inhibition. Consistent with the results obtained in animals, p38α was reduced in visceral and subcutaneous adipose tissue of subjects with obesity and was inversely correlated with body mass index (BMI).

Altogether, we have elucidated a mechanism implicated in physiological BAT activation that has potential clinical implications for the treatment of obesity and related diseases such as diabetes.


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