Caveolae-Associated Protein 3 (Cavin-3) Influences Adipogenesis via TACE-Mediated Pref-1 Shedding.

Phil June Park,Sung Tae Kim

doi:10.3390/ijms21145000

Abstract

Abnormal adipogenesis regulation is accompanied by a variety of metabolic dysfunctions and disorders. Caveolae play an important role in the regulation of fat production, modulated by caveolae-associated proteins (Cavin-1 to 4). Here, we investigated the role of Cavin-3 in lipogenesis and adipocyte differentiation, as the regulatory functions and roles of Cavin-3 in adipocytes are unknown. A Cavin-3 knockdown/overexpression stable cell line was established, and adipogenesis-related gene and protein expression changes were investigated by real-time quantitative PCR and Western blot analysis, respectively. Additionally, confocal immune-fluorescence microscopy was used to verify the intracellular position of the relevant factors. The results showed that Cavin-3 mRNA and protein expression were elevated, along with physiological factors such as lipid droplet formation, during adipogenesis. Cavin-3 silencing resulted in retarded adipocyte differentiation, and its overexpression accelerated this process. Furthermore, Cavin-3 knockdown resulted in decreased expression of adipogenesis-related genes, such as PPAR-γ, FAS, aP2, and Adipoq, whereas preadipocyte factor-1 (Pref-1) was markedly increased during adipocyte maturation. Overall, Cavin-3 influences caveolar stability and modulates the tumor necrosis factor-alpha-converting enzyme (TACE)-mediated Pref-1 shedding process in both mouse and human adipocytes. The Cavin-3-dependent shedding mechanism appears to be an important process in adipocyte maturation, providing a potential therapeutic target for obesity-related disorders.

Highlights

Adipose tissues, which store energy in the form of lipids, and mobilize this energy in response to increased energy demands imposed by exercise, fasting, and hormonal stimulation, are important for maintaining energy balance in the body [1,2]
To investigate the association between Cavin-3 and adipocyte differentiation, Western blot analysis was performed to assess the expression of Cavin-3 during maturation of 3T3-L1 adipocytes (Figure 1A) [30]
In siCavin-3 cells, the small fragment of Preadipocyte factor 1 (Pref-1) was undetectable by day 5 of differentiation (Figure S2E, center panel). These results suggest that the association between Cavin-3 and tumor necrosis factor-alpha-converting enzyme (TACE)-mediated Pref-1 cleavage could be one feasible mechanism for controlling adipocyte differentiation

Summary

Introduction

Adipose tissues, which store energy in the form of lipids, and mobilize this energy in response to increased energy demands imposed by exercise, fasting, and hormonal stimulation, are important for maintaining energy balance in the body [1,2]. Chronic excess energy intake relative to expenditure, and the consequent abnormal adipocyte differentiation and development of hyperplastic adipose tissue, can cause obesity and major health problems such as hypertension, heart disease, and diabetes mellitus [3,4,5,6,7]. The soluble forms of Pref-1 produced by TACE are reported to inhibit adipocyte differentiation by suppressing factors involved in the early stage of adipogenesis, namely the CCAAT/enhancer-binding protein beta and delta (C/EBPβ and C/EBPδ), via induction of Sox expression through activation of the MEK/ERK pathway [15]. Pref-1 expression decreases gradually during adipocyte differentiation, and decreased Pref-1 expression alone is sufficient to increase adipocyte differentiation [11]

Methods

Results

Conclusion