Research Article

Regulation of WNK4 gene transcription in the kidneys

Published: July 08, 2013
Genet. Mol. Res. 12 (3) : 2332-2340 DOI: 10.4238/2013.January.4.9

Abstract

With-no-lysine (K) kinase-4 (WNK4) is a newly cloned kinase-encoding gene that plays a crucial role in the maintenance of electrolyte homeostasis. Mutations of WNK4 can cause pseudohypoal­dosteronism type α, an autosomal dominant disease characterized by hyperkalemia, metabolic acidosis and hypertension. We explored the expression and regulatory mechanism of WNK4 in the human kidneys, which is a key regulator of blood pressure. Expression of WNK4 was determined by RT-PCR. Transcription initiation site and regulatory ele­ments in the promoter region of WNK4 were systematically analyzed with a combined set of experimental and bioinformatic methods. Us­ing 5'-RACE, we have determined the transcription initiation site. We identified a number of putative cis-acting elements by analysis of the promoter region with the TRANSFAC-TESS software; these were sub­sequently confirmed with an electrophoresis mobility shift assay. As con­firmed by a CAT-ELISA reporter assay, the promoter region of WNK4 has a high level of transcriptional activity. Several hormones, in particular dexamethasone, can suppress the level of WNK4 mRNA. These results have shed light on the regulatory mechanism of WNK4 expression in kid­neys, as well as the influence of various hormones on expression levels. This should prove useful for studies on the roles of WNK4 in the patho­genesis of hypertension.

With-no-lysine (K) kinase-4 (WNK4) is a newly cloned kinase-encoding gene that plays a crucial role in the maintenance of electrolyte homeostasis. Mutations of WNK4 can cause pseudohypoal­dosteronism type α, an autosomal dominant disease characterized by hyperkalemia, metabolic acidosis and hypertension. We explored the expression and regulatory mechanism of WNK4 in the human kidneys, which is a key regulator of blood pressure. Expression of WNK4 was determined by RT-PCR. Transcription initiation site and regulatory ele­ments in the promoter region of WNK4 were systematically analyzed with a combined set of experimental and bioinformatic methods. Us­ing 5'-RACE, we have determined the transcription initiation site. We identified a number of putative cis-acting elements by analysis of the promoter region with the TRANSFAC-TESS software; these were sub­sequently confirmed with an electrophoresis mobility shift assay. As con­firmed by a CAT-ELISA reporter assay, the promoter region of WNK4 has a high level of transcriptional activity. Several hormones, in particular dexamethasone, can suppress the level of WNK4 mRNA. These results have shed light on the regulatory mechanism of WNK4 expression in kid­neys, as well as the influence of various hormones on expression levels. This should prove useful for studies on the roles of WNK4 in the patho­genesis of hypertension.