alpha2D/A-adrenergic receptor gene induction in the retina by phorbol ester: involvement of an AP-2 element.
BACKGROUND
The alpha2-adrenergic receptor (alpha2-AR) expressed in the bovine retina has been demonstrated to be of the alpha2D subtype. The bovine alpha2D-adrenergic receptor (alpha2D/A-AR) gene has been cloned and characterized. This report describes the induction of this gene by phorbol- 12, 13-myristate acetate (PMA), an activator of protein kinase C (PKC).


RESULTS
Treatment of the bovine retina for 60 min with PMA (1 micrometer) resulted in significant and similar increases in alpha2D/A-AR mRNA level and gene transcription. This indicates that PMA causes alpha2D/A-AR gene induction and that this induction takes place directly at the transcriptional level. In C6 cells, treatment with PMA at a concentration which was as low as 0.1 micrometer induced endogenous alpha2D/A-AR mRNA after 60 min. Luciferase reporter assays in C6 cells mapped the PMA-responsive element to a region between -247 bp and -163 bp on the alpha2D/A-AR promoter. Electrophoretic mobility shift assays showed an increased binding of nuclear factor(s) from PMA-treated bovine retina to this promoter region. Competition assays indicate that an AP-2 element may be involved in the PMA-dependent induction.


CONCLUSIONS
These findings demonstrate for the first time, the direct induction of the alpha2D/A-AR gene by PMA and support a role for an AP-2 element in the induction mechanism.
D000818:Animals; D002417:Cattle; D005786:Gene Expression Regulation; D005910:Glioma; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D018341:Receptors, Adrenergic, alpha-2 / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D020218:Response Elements; D012160:Retina / Q000187:drug effects* / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured