CCAAT/enhancer binding protein alpha maintains the ability of insulin-stimulated GLUT4 translocation in 3T3-C2 fibroblastic cells.
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/EBPalpha, 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/EBPalpha was observed. We also created 3T3-C2 cells stably expressing both myc-tagged GLUT4 and C/EBPalpha, demonstrating that co-expressed cells showed insulin-stimulated GLUT4 translocation on day 8 after the induction, as well as adipose conversion coupling with PPARgamma expression. Our results provide evidence that C/EBPalpha has the potential to maintain the ability of insulin-stimulated GLUT4 translocation in C/EBPalpha-deficient 3T3-C2 fibroblastic cells.
Fujimoto
Muneya
M
Division of Endocrinology and Metabolism, Department of Medicine and Clinical Science, Kyoto University Graduate School of Medicine, 54, Sakyo-ku, Kyoto, 606-8507, Japan.
Masuzaki
Hiroaki
H
Yamamoto
Yuji
Y
Norisada
Nobuyoshi
N
Imori
Makoto
M
Yoshimoto
Masako
M
Tomita
Tsutomu
T
Tanaka
Tomohiro
T
Okazawa
Kayoko
K
Fujikura
Junji
J
Chusho
Hideki
H
Ebihara
Ken
K
Hayashi
Tatsuya
T
Hosoda
Kiminori
K
Inoue
Gen
G
Nakao
Kazuwa
K
D016475:3T3 Cells; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism*; D017930:Genes, Reporter; D016259:Genes, myc; D051275:Glucose Transporter Type 4; D007328:Insulin / Q000494:pharmacology*; D051379:Mice; D009004:Monosaccharide Transport Proteins / Q000187:drug effects / Q000378:metabolism*; D009124:Muscle Proteins / Q000187:drug effects / Q000378:metabolism*; D010957:Plasmids; D021381:Protein Transport / Q000187:drug effects*
D022763:CCAAT-Enhancer-Binding Protein-alpha; D051275:Glucose Transporter Type 4; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495693:Slc2a4 protein, mouse