Not – passed continuously in the culture dish. We did not find adipose tissues in vivo that express as little C/EBPa as the NIH/ 3T3 cells (Figure 7), so the significance of this C/EBPa independent pathway in normal adipocyte physiology is unclear. Identification of the alternative signals to turn on the target genes of C/EBPa may someday provide clues to new diabetes treatment.Materials and Methods Materials2-Deoxy-D-[2,6-3H]glucose was purchased from Amersham Pharmacia Title Loaded From File Biotech (Piscataway, NJ). Rosiglitazone was purchased from Title Loaded From File Cayman Chemical (Ann Arbor, MI). Akt and phosphoAkt(pS473) antibodies were from Epitomics (Burlingame, CA). IRS-1 antibody was from Upstate (Charlottesville, VA), and 4G10 was from Millipore (Billerica, MA). All other antibodies were from Genetex (Irvine, CA). The RNeasy total RNA kit was from QIAGEN (Valencia, CA). Reverse transcription reagents were obtained from Promega Corp. (Madison, WI) and TaqMan reagents were from PE Applied Biosystems (Foster City, CA). All other reagents were from Sigma (St. Louis, MO).Tissue Culture3T3-L1 fibroblasts (ATCC, Manassas, VA) were maintained at no higher than 70 confluence in DMEM (Dulbecco’s Modified Eagle Medium)/CS (DMEM containing 10 calf serum, 25 mM glucose, 2 mM glutamine). For differentiation they were grown 2 days post confluence in the same medium and then for 3 days in 3T3-L1 induction cocktail (DMEM containing 10 fetal bovine serum, 25 mM glucose, 2 mM glutamine, supplemented with 1 mM dexamethasone, and 0.5 mM isobutylmethylxanthine). The medium was then changed to DMEM/FBS (DMEM containing 10 fetal bovine serum, 25 mM glucose, 2 mM glutamine) for 6 days (change medium every 48 hours) before use. NIH/3T3 fibroblasts (ATCC, Manassas, VA) were maintained at no higher than 70 confluence in DMEM/CS. For differentiation they were grown 2 days post confluence in the same medium and then for 7 days in an adipogenic cocktail containing rosiglitazone (DMEM containing 20 fetal bovine serum, 25 mM glucose, 2 mM glutamine, supplemented with 1 mM dexamethasone, 0.5 mM isobutylmethylxanthine, and 4.5 mM rosiglitazone) or 14 days in an adipogenic cocktail without rosiglitazone. The medium was then changed to DMEM/FBS for 8 days (change medium on every 72 hours) before use.Figure 4. Temporal expression profiles of the C/EBPs during differentiation of 3T3-L1 and NIH/3T3 cells. The mRNA levels and the standard errors (n = 3) of measurement of (A) C/EBPa, (B) C/EBPb, and (C) C/EBPd were determined by qPCR and normalized by Gapdh signal on day 0 (D0), 2 (D2) and 4(D4) in differentiation medium and day 8 in DMEM +10 FBS medium. doi:10.1371/journal.pone.0051459.gExcept for the differences in the expression profiles of the C/ EBPs, the insulin signaling patterns of NIH/3T3 and 3T3-L1 adipocytes did not show significant difference. The western blot analysis of the PI3K/Akt pathway in NIH/3T3 shown in Figure 5. The NIH/3T3 adipocytes are a suitable and easier to work with than the 3T3-L1 system to study insulin action. Body weight gain is associated with development of insulin resistance and higher blood pressure. It was seemingly paradoxical that diabetic patients treated with rosiglitazone gained even more weight but showed less insulin resistance and lower blood pressure [22]. The results presented above may provide clues to solve the paradox between obesity and insulin resistance. 24272870 Figure 1 showed that NIH/3T3 adipocytes induced in the presence of rosiglitazone formed adipo.Not – passed continuously in the culture dish. We did not find adipose tissues in vivo that express as little C/EBPa as the NIH/ 3T3 cells (Figure 7), so the significance of this C/EBPa independent pathway in normal adipocyte physiology is unclear. Identification of the alternative signals to turn on the target genes of C/EBPa may someday provide clues to new diabetes treatment.Materials and Methods Materials2-Deoxy-D-[2,6-3H]glucose was purchased from Amersham Pharmacia Biotech (Piscataway, NJ). Rosiglitazone was purchased from Cayman Chemical (Ann Arbor, MI). Akt and phosphoAkt(pS473) antibodies were from Epitomics (Burlingame, CA). IRS-1 antibody was from Upstate (Charlottesville, VA), and 4G10 was from Millipore (Billerica, MA). All other antibodies were from Genetex (Irvine, CA). The RNeasy total RNA kit was from QIAGEN (Valencia, CA). Reverse transcription reagents were obtained from Promega Corp. (Madison, WI) and TaqMan reagents were from PE Applied Biosystems (Foster City, CA). All other reagents were from Sigma (St. Louis, MO).Tissue Culture3T3-L1 fibroblasts (ATCC, Manassas, VA) were maintained at no higher than 70 confluence in DMEM (Dulbecco’s Modified Eagle Medium)/CS (DMEM containing 10 calf serum, 25 mM glucose, 2 mM glutamine). For differentiation they were grown 2 days post confluence in the same medium and then for 3 days in 3T3-L1 induction cocktail (DMEM containing 10 fetal bovine serum, 25 mM glucose, 2 mM glutamine, supplemented with 1 mM dexamethasone, and 0.5 mM isobutylmethylxanthine). The medium was then changed to DMEM/FBS (DMEM containing 10 fetal bovine serum, 25 mM glucose, 2 mM glutamine) for 6 days (change medium every 48 hours) before use. NIH/3T3 fibroblasts (ATCC, Manassas, VA) were maintained at no higher than 70 confluence in DMEM/CS. For differentiation they were grown 2 days post confluence in the same medium and then for 7 days in an adipogenic cocktail containing rosiglitazone (DMEM containing 20 fetal bovine serum, 25 mM glucose, 2 mM glutamine, supplemented with 1 mM dexamethasone, 0.5 mM isobutylmethylxanthine, and 4.5 mM rosiglitazone) or 14 days in an adipogenic cocktail without rosiglitazone. The medium was then changed to DMEM/FBS for 8 days (change medium on every 72 hours) before use.Figure 4. Temporal expression profiles of the C/EBPs during differentiation of 3T3-L1 and NIH/3T3 cells. The mRNA levels and the standard errors (n = 3) of measurement of (A) C/EBPa, (B) C/EBPb, and (C) C/EBPd were determined by qPCR and normalized by Gapdh signal on day 0 (D0), 2 (D2) and 4(D4) in differentiation medium and day 8 in DMEM +10 FBS medium. doi:10.1371/journal.pone.0051459.gExcept for the differences in the expression profiles of the C/ EBPs, the insulin signaling patterns of NIH/3T3 and 3T3-L1 adipocytes did not show significant difference. The western blot analysis of the PI3K/Akt pathway in NIH/3T3 shown in Figure 5. The NIH/3T3 adipocytes are a suitable and easier to work with than the 3T3-L1 system to study insulin action. Body weight gain is associated with development of insulin resistance and higher blood pressure. It was seemingly paradoxical that diabetic patients treated with rosiglitazone gained even more weight but showed less insulin resistance and lower blood pressure [22]. The results presented above may provide clues to solve the paradox between obesity and insulin resistance. 24272870 Figure 1 showed that NIH/3T3 adipocytes induced in the presence of rosiglitazone formed adipo.
