Adipose cell size changes are associated with a drastic actin remodeling.

Area of Science:

• Cell Biology
• Metabolism
• Physiology

Background:

• Adipose tissue is crucial for insulin sensitivity and energy metabolism.
• Adipocyte size (hypertrophy) and number (hyperplasia) increase to store excess energy.
• Enlarged adipocytes show reduced insulin responsiveness, predicting type 2 diabetes.

Purpose of the Study:

• To investigate the link between adipocyte size changes and actin cytoskeleton remodeling.
• To understand how diet-induced adipocyte expansion affects insulin sensitivity.
• To explore the role of actin cytoskeleton in adipocyte function during metabolic changes.

Main Methods:

• Primary adipocyte expansion induced by high-fat diet (HFD) in C57BL6/J mice.
• Assessment of filamentous (F)-actin using fluorescence microscopy.
• Measurement of Rho-kinase activity and expression of actin-regulating proteins.
• Evaluation of insulin response and protein interactions (IQGAP1 and IRS-1).

Main Results:

• Adipocyte expansion correlated with increased F-actin, Rho-kinase activity, and actin polymerization.
• Increased adipocyte size was associated with impaired insulin response.
• Reversed feeding (HFD to chow) normalized cell size, insulin response, and actin cytoskeleton.
• The interaction between IQGAP1 and IRS-1 remained intact despite cell size changes.

Conclusions:

• Adipocyte expansion involves significant actin cytoskeleton remodeling.
• Cytoskeletal changes during adipocyte expansion may contribute to impaired adipocyte function and insulin resistance.
• Dietary interventions can reverse these detrimental cytoskeletal and functional changes in adipocytes.