Figure 6

The roles of CBP and p300 in CLOCK/BMAL1-mediated transcription in MCF7 and COS-1 cells. (A) MCF7 cells were transiently transfected with either pE-less (white-bar) or pE-box (2 ng), together with (black-bar) or without (gray-bar) pcDNA3CLOCK (20 ng) plus pcDNA3BMAL1 (20 ng) in combination with increasing amounts of pcDNA3CBP (0, 10, 20, 50 or 100 ng), as indicated. Empty vector (pcDNA3) was used to standardize the total amount of transfected DNA (402 ng). pCMVβ (100 ng) was cotransfected as a control for transfection efficiency. An asterisk indicates p < 0.05 compared with black-bar in lane 1 (E-box + CL/BM; Student's t test). (B) COS-1 cells were transiently transfected with pPeriod1-Luc (10 ng), together with or without pcDNA3CLOCK (10 ng) plus pcDNA3BMAL1 (10 ng) alone or in combination with pcDNA3CBP or pCMV-p300 (100 ng), as indicated. Empty vector (pcDNA3) was used to standardize the total amount of transfected DNA (410 ng). An asterisk indicates p < 0.05 (Student's t test, n = 6). (C) COS-1 cells were transiently transfected with pGAL4RE-Luc (5 ng), together with either pGAL4, pGAL4-CLOCK or pGAL4-BMAL1 (100 ng) alone or in combination with pcDNA3CLOCK or pcDNA3BMAL1 (100 ng), in the presence or absence of pcDNA3CBP (100 ng), as indicated. Empty vector (pcDNA3) was used to standardize the total amount of transfected DNA (405 ng). An asterisk indicates p < 0.05 (Student's t test). (A, B) Luciferase activity was expressed as a ratio of CLOCK/BMAL1-mediated reporter activity.