Author:
Golbang Amir P.,Cope Georgina,Hamad Abbas,Murthy Meena,Liu Che-Hsiung,Cuthbert Alan W.,O’Shaughnessy Kevin M.
Abstract
The novel serine/threonine kinases (with no lysine kinases or WNKs), WNK1 and WNK4, are encoded by the disease genes for Gordon syndrome (PRKWNK1 and PRKWNK4), a rare monogenic syndrome of hypertension and hyperkalemia. These proteins alter the expression of the thiazide-sensitive Na/Cl cotransporter (NCCT) in Xenopus laevis oocytes, although the details are controversial. We describe here our own experience and confirm that kinase-dead WNK4 (318D>A) is unable to affect Na+fluxes through the thiazide-sensitive Na/Cl transporter (NCCT) or its membrane expression as an ECFP-NCCT fusion protein. However, the kinase domain is not sufficient for a functional WNK4 since deletion of the acidic motif (a motif unique to WNK family members) completely abolishes functional activity. Indeed, the NH2terminal of WNK4 (1–620) containing the kinase domain and acidic motif retains full activity, but does not interact directly with NCCT in pull-down assays. Coexpression of WNK1 antagonizes the action of WNK4, and kinase-dead WNK1 (368D>A) or WNK1 carrying a WNK4 disease mutation (565Q>E) behaves in the same way as wild-type WNK1. This suggests kinase activity and charge conservation within the acidic motif are not essential for the WNK1-WNK4 interaction. We also report that WNK4 probably reduces surface expression largely through an effect on forward trafficking. Hence, the effect of WNK4 on NCCT expression is mimicked by dynamin, but the dominant-negative K44A dynamin mutant does not block the action of WNK4 itself. These results further highlight important differences in the mechanism by which WNK kinases affect expression of NCCT vs. other membrane proteins such as ROMK.
Publisher
American Physiological Society
Reference25 articles.
1. Cope G, Golbang A, Murthy M, Hamad A, Liu CH, Hoff WV, Cuthbert A, and O’Shaughnessy KM.The origin of hyperkalaemia in Gordon’s syndrome: WNK1 interacts directly with the potassium channel ROMK to reduce its surface expression in Xenopus oocytes.J Hum Hypertens19: 832, 2005.
2. WNK kinases and the control of blood pressure
3. Mutations in the Na-Cl Cotransporter Reduce Blood Pressure in Humans
4. Multiple Promoters in the WNK1 Gene: One Controls Expression of a Kidney-Specific Kinase-Defective Isoform
5. Gamba G, Miyanoshita A, Lombardi M, Lytton J, Lee WS, Hediger MA, and Hebert SC.Molecular cloning, primary structure, and characterization of two members of the mammalian electroneutral sodium-(potassium)-chloride cotransporter family expressed in kidney.J Biol Chem269: 17713–17722, 1994.
Cited by
72 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献