TAK1 regulates skeletal muscle mass and mitochondrial function

Area of Science:

• Molecular biology
• Skeletal muscle physiology
• Cell signaling

Background:

• Skeletal muscle mass is tightly regulated by intricate signaling networks.
• TGF-β-activated kinase 1 (TAK1) is a key signaling molecule involved in various cellular processes.
• The specific role of TAK1 in skeletal muscle mass regulation was previously undefined.

Purpose of the Study:

• To investigate the function of TAK1 in the regulation of skeletal muscle mass.
• To elucidate the molecular mechanisms by which TAK1 influences muscle homeostasis.
• To determine TAK1's role in muscle adaptation to different physiological stimuli.

Main Methods:

• Inducible genetic inactivation of TAK1 in mouse models (young and adult).
• Assessment of muscle mass, protein synthesis, and proteolysis markers.
• Analysis of key signaling pathways including AMPK, mTOR, and p38 MAPK.
• Evaluation of mitochondrial function and oxidative stress.
• Investigation of TAK1's role in response to denervation and functional overload.

Main Results:

• Inducible TAK1 inactivation in mice resulted in significant muscle wasting and kyphosis.
• TAK1 inhibition suppressed protein synthesis and enhanced proteolysis via ubiquitin-proteasome and autophagy pathways.
• AMPK activity increased, while phosphorylated mTOR and p38 MAPK decreased upon TAK1 inactivation.
• Mice with TAK1 inactivation exhibited mitochondrial dysfunction and oxidative stress.
• TAK1 inhibition did not prevent denervation-induced muscle atrophy but blocked overload-induced hypertrophy.
• TAK1 activity was upregulated during functional overload-induced muscle growth.

Conclusions:

• TAK1 is an essential regulator of skeletal muscle mass, impacting both anabolic and catabolic processes.
• TAK1 plays a critical role in maintaining skeletal muscle oxidative metabolism and mitochondrial health.
• Targeting TAK1 may offer therapeutic potential for muscle wasting conditions, but its role in overload-induced growth suggests complex regulation.