Submitochondrial Protein Translocation in Thermogenic Regulation

Area of Science:

• Mitochondrial bioenergetics
• Cellular metabolism
• Obesity pathogenesis

Background:

• Brown adipocytes dissipate energy as heat via thermogenic energy expenditure (TEE).
• Obesity arises from impaired TEE due to nutrient excess or cold exposure, with unclear mechanisms.
• Mitochondrial inner membrane (IM) protein dynamics are implicated in metabolic regulation.

Purpose of the Study:

• Investigate mechanisms linking mitochondrial dysfunction to obesity.
• Identify proteins translocating within mitochondria during stress.
• Determine the role of identified proteins in thermogenesis and obesity.

Main Methods:

• Analysis of protein translocation in mitochondria under stress conditions.
• Proteomic analysis to identify proteins migrating from IM to matrix.
• Biochemical assays to assess enzymatic activity and substrate utilization.
• In vivo studies using mouse models to evaluate the impact of protein manipulation on obesity.

Main Results:

• Stress induces proton leak, causing IM proteins to translocate into the mitochondrial matrix.
• A subset of these proteins correlates with obesity in human adipose tissue.
• Acyl-CoA thioesterase 9 (ACOT9) translocates to the matrix upon stress, deactivating acetyl-CoA utilization in TEE.
• Loss of ACOT9 protects mice from obesity complications by preserving TEE.

Conclusions:

• Aberrant mitochondrial protein translocation is a key mechanism in obesity pathogenesis.
• ACOT9 is a critical factor linking stress-induced mitochondrial dysfunction to impaired TEE and obesity.
• Targeting stress-induced protein translocation offers a novel strategy for obesity treatment.