Identification of a novel 12-nucleotide insertion polymorphism in the promoter region of ADRA2B: full linkage with the 9-nucleotide deletion in the coding region and influence on transcriptional activity

Pierre-Antoine Crassous , Régis Blaise , Amélie Marquette , Amir Snapir , Mika Scheinin , Hervé Paris , Stéphane Schaak

The α-adrenoceptor (α-AR) mediates vasoconstriction and a common polymorphism (+901 Ins/Del), located in the coding region of the human α-AR gene (ADRA2B), has been demonstrated to affect receptor function . In this study, we have identified a novel polymorphism corresponding to the insertion of 12 nucleotides (GGGACGGCCCTG) at position -4825 relative to the start codon (-4825 del/ins) in the far upstream region of the ADRA2B promoter. The genotyping of 71 unrelated Finnish individuals showed that the -4825 ins polymorphism is common and in complete linkage with the Del polymorphism at position +901 and a G/C substitution at position -98. Transfection of various cell lines with luciferase constructs containing a 5.5kb fragment of the ADRA2B promoter region indicated that the -4825 ins polymorphism resulted in a large reduction of transcriptional activity. Electrophoretic mobility shift assays with oligonucleotide probes corresponding to the two ADRA2B alleles demonstrated that the region where the -4825 del/ins variation occurs binds nuclear proteins and that the 12 nucleotide insertion affects the pattern of bound transcription factors. Altogether, the present findings show that the previously identified +901 Del polymorphism is linked with a variation in the ADRA2B promoter that affects transcriptional activity . The molecular mechanisms underlying this effect are still unclear but a possible impact of the -4825 ins polymorphism on α-AR expression would merit to be examined as a diminution of promoter activity may limit the functional consequences of the +901 Del polymorphism.

Mots clés: adrenoceptor; ADRA2B promoter; polymorphism; transcription; haplotype

Pierre-Antoine Crassous, Régis Blaise, Amélie Marquette, Amir Snapir, Mika Scheinin, et al.. Identification of a novel 12-nucleotide insertion polymorphism in the promoter region of ADRA2B: full linkage with the 9-nucleotide deletion in the coding region and influence on transcriptional activity. Biochemical Pharmacology, 2009, 79 (3), pp.407. ⟨10.1016/j.bcp.2009.08.024⟩. ⟨hal-00538092⟩