Rosiglitazone-induced white adipocyte browning is regulated by actin and Myh9.

AIMS

This study investigates the role of actin polymerization and Myh9 in mediating lipid droplet (LD) fission during rosiglitazone-induced browning of white adipocytes. The aim is to understand how LD splitting might contribute to the beige conversion of white adipose tissue, providing insights into adipocyte plasticity and metabolic regulation.

MATERIALS AND METHODS

C3H10 T1/2-differentiated adipocytes were used as a classical model to study white adipocyte browning. Rosiglitazone was applied to induce browning, and the interactions between LDs and actin, as well as the distribution of Myh9, were assessed using immunofluorescence and Western blotting. In vivo, we employed a microfilament inhibitor to block actin polymerization in cold-stimulated mice and evaluated changes in LD morphology and browning. Furthermore, dynamic live-cell imaging using confocal microscopy was conducted to observe the real-time behavior of LDs during the browning process and to determine whether they undergo fission.

MAIN FINDINGS

Our results demonstrate that rosiglitazone significantly induces LD size reduction, a process correlated with the increased contact of LDs with microfilaments. Inhibition of actin polymerization prevented both the reduction in LD size and the browning of white adipocytes, indicating that actin plays a critical role. Myh9 was enriched at the LD fission sites, forming a structure resembling a contractile ring. Overexpression of Myh9 promoted the shrinkage of LD, suggesting that it may be involved in LD fission.

SIGNIFICANCE

This study identifies actin and Myh9 as key regulators of LD fission in rosiglitazone-induced browning of white adipocytes, offering new insights into the cellular mechanisms of adipocyte plasticity. The findings propose a novel pathway by which LD dynamics contribute to the beige conversion of white fat, with potential implications for metabolic disease therapies targeting adipocyte function and energy expenditure.