Inhibition of cyclic AMP response element-binding protein/cyclic AMP response element-mediated transcription by the immunosuppressive drugs cyclosporin A and FK506 depends on the promoter context.
The immunosuppressants cyclosporin A and FK506 (tacrolimus) can block the phosphatase calcineurin, thereby inhibiting gene transcription directed by the cyclic AMP (cAMP)- and calcium-responsive transcription factor, cAMP response element (CRE)-binding protein, and its binding site, CRE, in various cell lines. This action is a novel molecular mechanism of cyclosporin A and FK506 action. Because inhibition of CREB/CRE-directed transcription by cyclosporin A and FK506 has previously been observed by using synthetic minienhancers, reporter fusion genes were constructed to examine the effect of cyclosporin A and FK506 on the transcriptional activity of CRE-containing natural promoters. In transient transfection experiments, cyclosporin A and FK506 inhibited the transcriptional activation by cAMP and the membrane depolarization of three CRE-containing promoters. However, cyclosporin A and FK506 failed to inhibit the activation by cAMP of another promoter, the rat insulin I gene promoter. The lack of cyclosporin A/FK506 sensitivity is not intrinsic to the insulin CRE because cyclosporin A and FK506 inhibited the activation by cAMP of the insulin CRE when isolated and used as a synthetic minienhancer. Rather, cyclosporin A/FK506 resistance may be conferred by specific promoter interactions because a mutational analysis of the insulin promoter revealed that inside this promoter, CRE activity depends on an adjacent control element. These data show that cyclosporin A and FK506 can inhibit CRE activity when the CRE resides in its natural promoter. However, the cyclosporin A/FK506 sensitivity depends on the specific promoter context. The results suggest that cyclosporin A and FK506 may alter target tissue function through the regulation of a subset of CRE-containing genes.
Siemann
G
G
Department of Molecular Pharmacology, University of Göttingen, Göttingen, Germany.
Blume
R
R
Grapentin
D
D
Oetjen
E
E
Schwaninger
M
M
Knepel
W
W
D000818:Animals; D001483:Base Sequence; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology*; D017362:Cyclic AMP Response Element-Binding Protein / Q000037:antagonists & inhibitors* / Q000235:genetics; D016572:Cyclosporine / Q000494:pharmacology*; D005786:Gene Expression Regulation; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007328:Insulin / Q000235:genetics; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D051381:Rats; D016415:Sequence Alignment; D016559:Tacrolimus / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects
D017362:Cyclic AMP Response Element-Binding Protein; D007166:Immunosuppressive Agents; D007328:Insulin; D005576:Colforsin; D016572:Cyclosporine; D000242:Cyclic AMP; D016559:Tacrolimus