9B.02

Abstract

Objective: We previously showed that a blunted expression of the Twik-related Acid-Sensitive K+ channel 2 (TASK-2) is a common feature of Aldosterone Producing Adenoma (APA). Thus, we aimed at investigating the presence of mutations in the promoter region of the TASK-2 gene (KCNK5) in APA. Design and method: We sequenced the entire TASK-2 promoter region of 88 APA and 98 primary hypertensive patients (controls). We next tested the in vitro effects of the most frequently detected mutation by fusing the mutated and wild type TASK-2 promoter region to the luciferase coding sequence and transfecting the reporter vectors in H295R cells. Results: We detected only one mutation (C999T) in one of 98 primary hypertensive patients. Seven novel mutations were found in 16% of APA: the C999T variant was found in 6% of APA, the G595A in 3.5% of APA, the G36A in 2% of APAs, while the Gins466, G263C, C1247T and G1140T mutations in 1% of APA. None was germline. By site-direct mutagenesis we demonstrated that the C999T mutation significantly decreased the TASK-2 transcription activity and luciferase signal of the reporter vector in transfected H295R cells (fold change of normalized luciferase signal: 0.55 ± 0.22, p Conclusions: Thus, we demonstrated that 16% of APA have seven recurrent mutations in the promoter region of TASK-2 gene. One of these TASK-2 genetic variants blunts the transcription of the TASK-2 in human adrenal cells, thus suggesting a possible molecular mechanism contributing to the autonomous aldosterone secretion typical of APA.