Investigation of adipocyte proteome during the differentiation of brown preadipocytes

Abstract

Brown adipocytes oxidize fatty acids to produce heat in response to cold or caloric overfeeding. The motivation and function of the development of brown fat may thus counteract obesity, though this remains uncertain. We investigated the brown adipocyte proteome by two-dimensional gel electrophoresis followed by mass spectrometry. Comparative analyses of proteins focused on total protein spots to filter differentially expressed proteins during the differentiation of mouse primary brown preadipocytes. A Western blot analysis was performed to verify the target proteins. The results indicated that 10 protein spots were differentially expressed with significant changes, including the three up-regulated proteins of prohibitin, hypoxanthine-guanine phosphoribosyltransferase, and enoyl-CoA hydratase protein; the 5 down-regulated proteins of triosephosphate isomerase, elongation factor 2, α-tropomyosin slow, endophilin-B1, and cofilin-1 (CFL1); and the two unequivocally expressed proteins of peroxiredoxin-1 and collagen α-1(i) chain precursor. We found that during brown adipogenesis, CFL1 has an inhibitory effect on brown adipocyte differentiation. The overexpression of CFL1 inhibited the brown fat deposition and repressed the brown marker genes UCP1, PRDM16, PGC-1α and PPARγ via actin dynamics and polymerization. These observations may be novel findings that bring new insight into the detailed mechanisms of brown adipogenesis and identify possible therapeutic targets for anti-obesity.

Biological significance: We use 2-DE to compare the proteomes of adipocytes during the brown adipogenesis of primary mouse preadipocytes. We identified 10 proteins that are differentially expressed. Among these, we found that the actin binding protein CFL1 inhibits the differentiation of brown preadipocytes. CFL1 overexpressing cells showed lower deposition of brown fat droplets, and the brown marker genes of UCP1, PRDM16, PGC-1α and PPARγ were decreased through actin dynamics and polymerization.

Keywords: AIP1; APRT; Adipogenesis; BAT; Brown adipocyte; CAP; CFL-1; COL1A1; Cofilin-1; ECHS1; EEF-2; EndoB1; HPRT; LIM kinase; LIMK; Obesity; PHB; PRX-1; Proteomics; TESK; TPI; TPM3; actin-interacting protein-1; adenine phosphoribosyltransferase; brown adipose tissue; cofilin-1; collagen alpha-1(i) chain; cyclase-associated protein; elongation factor 2; endophilin B1; enoyl-CoA hydratase; hypoxanthine–guanine phosphoribosyltransferase; peroxiredoxin-1; prohibitin; testicular protein kinase; triosephosphate isomerase; α-tropomyosin slow..