CCAAT/enhancer binding protein α maintains the ability of insulin-stimulated GLUT4 translocation in 3T3-C2 fibroblastic cells

• Published in: Biochimica et biophysica acta 2005-08, Vol.1745 (1), p.38-47
• Main Authors: Fujimoto, Muneya, Masuzaki, Hiroaki, Yamamoto, Yuji, Norisada, Nobuyoshi, Imori, Makoto, Yoshimoto, Masako, Tomita, Tsutomu, Tanaka, Tomohiro, Okazawa, Kayoko, Fujikura, Junji, Chusho, Hideki, Ebihara, Ken, Hayashi, Tatsuya, Hosoda, Kiminori, Inoue, Gen, Nakao, Kazuwa
• Format: Article
• Language: English
• Subjects: 3T3 Cells; 3T3-C2 fibroblast; Adipocytes - drug effects; Adipocytes - metabolism; Adipogenesis; Animals; C/EBPα; CCAAT-Enhancer-Binding Protein-alpha - deficiency; CCAAT-Enhancer-Binding Protein-alpha - genetics; CCAAT-Enhancer-Binding Protein-alpha - metabolism; Fibroblasts - metabolism; Genes, myc; Genes, Reporter; Glucose Transporter Type 4; GLUT4 translocation; Insulin - pharmacology; Mice; Monosaccharide Transport Proteins - drug effects; Monosaccharide Transport Proteins - metabolism; Muscle Proteins - drug effects; Muscle Proteins - metabolism; Peroxisome proliferator-activated receptor γ; Plasmids; Protein Transport - drug effects
• ISSN: 0167-4889; 0006-3002; 1879-2596
• DOI: 10.1016/j.bbamcr.2004.12.007

In 3T3-L1 preadipocytes, hormonal induction causes adipose conversion and facilitates the expression of insulin-sensitive glucose transporter, GLUT4. Evidence has accumulated that, in 3T3-L1 preadipocytes, the formation of GLUT4 storage vesicle and its translocation to plasma membrane precede both lipid accumulation and expression of GLUT4 and C/EBPα, a key transcription factor for adipose differentiation. On the other hand, 3T3-C2 fibroblastic cells, a subline of 3T3-L1, follow adipogenic process till mitotic clonal expansion stage (2 days after hormonal induction), but do not proceed to terminal differentiation stage (8 days after the induction), resulting in a lack of adipose conversion and GLUT4 expression. Here we show that, when myc-tagged GLUT4 was retrovirally expressed in 3T3-C2 cells, insulin-stimulated GLUT4 translocation did occur on day 2 after the induction. On day 8 after the induction, however, neither GLUT4 translocation nor the expression of C/EBPα was observed. We also created 3T3-C2 cells stably expressing both myc-tagged GLUT4 and C/EBPα, demonstrating that co-expressed cells showed insulin-stimulated GLUT4 translocation on day 8 after the induction, as well as adipose conversion coupling with PPARγ expression. Our results provide evidence that C/EBPα has the potential to maintain the ability of insulin-stimulated GLUT4 translocation in C/EBPα-deficient 3T3-C2 fibroblastic cells.