Autoregulation of the human D-1A dopamine receptor gene by cAMP

作者:Minowa MT; Lee SH; Mouradian MM
来源:DNA and Cell Biology, 1996, 15(9): 759-767.
DOI:10.1089/dna.1996.15.759

摘要

Stimulation of the D-1A dopamine receptor increases intracellular cAMP concentration and down-regulates the receptor protein, We evaluated the possibility that this second messenger system could affect the expression of the D-1A gene as a positive autoregulatory mechanism, Treatment of the D-1A-expressing cells SK-NMC with 100 mu M dopamine resulted in an initial increase in steady-state levels of the D-1A mRNA beginning at 30 min, followed by decline below the baseline and then recovery by 24 hr, Forskolin/IBMX (100 mu M each) treatment also resulted in a decline followed by recovery, To determine if these changes in D-1A message levels are due to transcriptional control, transient expression assays were done using reporter gene constructs of the human D-1A gene 5'-flanking region, Forskolin/IBMX treatment for 19 hr resulted in a four- to sevenfold increase in trans-activation of the human D-1A gene promoter, Two cAMP-responsive regions in exon 1 of this gene with nuclear protein binding sites within both regions were identified, The segment of the D-1A gene between these two cAMP-responsive regions contained two additional DNA-protein interaction sites, one of which bound to nuclear factors considerably stronger following forskolin/IBMX treatment, Several consensus sequences for classical transcription factors known to mediate the cAMP response, such as CREB, AP2, and AP1, are found in the human D-1A gene, However, the location of all but one AP2 site in other parts of this gene and lack of AP2 expression in SK-N-MC cells suggest that these factors are unlikely to transduce this response, Thus, dopamine treatment results in delayed cAMP-mediated trans-activation of the D-1A gene via an indirect mechanism.

  • 出版日期1996-9

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