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P38α MAPK Coordinates Mitochondrial Adaptation to Caloric Surplus in Skeletal Muscle

Overview
Journal Int J Mol Sci
Publisher MDPI
Date 2024 Jul 27
PMID 39063031
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Abstract

Excessive calorie intake leads to mitochondrial overload and triggers metabolic inflexibility and insulin resistance. In this study, we examined how attenuated p38α activity affects glucose and fat metabolism in the skeletal muscles of mice on a high-fat diet (HFD). Mice exhibiting diminished p38α activity (referred to as p38α) gained more weight and displayed elevated serum insulin levels, as well as a compromised response in the insulin tolerance test, compared to the control mice. Additionally, their skeletal muscle tissue manifested impaired insulin signaling, leading to resistance in insulin-mediated glucose uptake. Examination of muscle metabolites in p38α mice revealed lower levels of glycolytic intermediates and decreased levels of acyl-carnitine metabolites, suggesting reduced glycolysis and β-oxidation compared to the controls. Additionally, muscles of p38α mice exhibited severe abnormalities in their mitochondria. Analysis of myotubes derived from p38α mice revealed reduced mitochondrial respiratory capacity relative to the myotubes of the control mice. Furthermore, these myotubes showed decreased expression of Acetyl CoA Carboxylase 2 (ACC2), leading to increased fatty acid oxidation and diminished inhibitory phosphorylation of pyruvate dehydrogenase (PDH), which resulted in elevated mitochondrial pyruvate oxidation. The expected consequence of reduced mitochondrial respiratory function and uncontrolled nutrient oxidation observed in p38α myotubes mitochondrial overload and metabolic inflexibility. This scenario explains the increased likelihood of insulin resistance development in the muscles of p38α mice compared to the control mice on a high-fat diet. In summary, within skeletal muscles, p38α assumes a crucial role in orchestrating the mitochondrial adaptation to caloric surplus by promoting mitochondrial biogenesis and regulating the selective oxidation of nutrients, thereby preventing mitochondrial overload, metabolic inflexibility, and insulin resistance.

References
1.
Odeh M, Tamir-Livne Y, Haas T, Bengal E . P38α MAPK coordinates the activities of several metabolic pathways that together induce atrophy of denervated muscles. FEBS J. 2019; 287(1):73-93. DOI: 10.1111/febs.15070. View

2.
Chandel N . Amino Acid Metabolism. Cold Spring Harb Perspect Biol. 2021; 13(4). PMC: 8015690. DOI: 10.1101/cshperspect.a040584. View

3.
Papaconstantinou J, Wang C, Zhang M, Yang S, Deford J, Bulavin D . Attenuation of p38α MAPK stress response signaling delays the in vivo aging of skeletal muscle myofibers and progenitor cells. Aging (Albany NY). 2015; 7(9):718-33. PMC: 4600628. DOI: 10.18632/aging.100802. View

4.
Randle P, Garland P, Hales C, Newsholme E . The glucose fatty-acid cycle. Its role in insulin sensitivity and the metabolic disturbances of diabetes mellitus. Lancet. 1963; 1(7285):785-9. DOI: 10.1016/s0140-6736(63)91500-9. View

5.
Antonioli L, Pellegrini C, Fornai M, Tirotta E, Gentile D, Benvenuti L . Colonic motor dysfunctions in a mouse model of high-fat diet-induced obesity: an involvement of A adenosine receptors. Purinergic Signal. 2017; 13(4):497-510. PMC: 5714840. DOI: 10.1007/s11302-017-9577-0. View