Genomic structure and regulation of kcn1, a cyclic gmp-gated
potassium channel.
Yao, Xiaoqiang, Yong Liu, Freeman Tung, and Gary V. Desir.
Department of Medicine, Section of Nephrology, Yale University
School of Medicine, West Haven VA medical Center, 2073 LMP, 333 Cedar
street, New Haven CT 06510
APStracts 3:0025F, 1996.
We recently cloned a novel rabbit gene that encodes a 725 amino acid
protein (Kcn1) (In press, 1995 PNAS). Kcn1 RNA injected in Xenopus
oocytes leads to the expression of potassium (K+) channels that are
specifically activated by cGMP. Northern blot and RNAase protection
analysis show that Kcn1 is differentially expressed in kidney, aorta,
brain and heart. The purpose of present study is to determine the
structure of Kcn 1 gene, analyze promoter region and identify cis
regulatory elements responsible for transcription. We find that the
coding region of Kcn is intronless. The major transcription
initiation site (TIS) was identified by primer extension. Sequence
analysis of the 5' flanking region indicates that while the gene
lacks a typical TATA box, it does have a TATA box like region (-TAT
-). Using luciferase reporter constructs transfected in the porcine
kidney cell line (LLC-PK1), the promoter region and a 5' enhancer
element were identified by deletion analysis. Phorbol esters (TPA)
and forskolin (FK) stimulated Kcn1 gene expression 2.5 and 3.5 fold
respectively. In conclusion, we have identified the region of the
novel potassium channel gene, Kcn1, that contains the promoter, a 5'
enhancer and several cis regulatory elements and shown that gene
transcription is stimulated by cAMP and phorbol esters.
Received 20 September 1995; accepted in final form 19 December
1995.
APS Manuscript Number F318-5.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 February 96