Downregulation of NCC and NKCC2 cotransporters by kidney-specific WNK1 revealed by gene disruption and transgenic mouse models.
WNK1 (with-no-lysine[K]-1) is a protein kinase of which mutations cause a familial hypertension and hyperkalemia syndrome known as pseudohypoaldosteronism type 2 (PHA2). Kidney-specific (KS) WNK1 is an alternatively spliced form of WNK1 kinase missing most of the kinase domain. KS-WNK1 downregulates the Na(+)-Cl(-) cotransporter NCC by antagonizing the effect of full-length WNK1 when expressed in Xenopus oocytes. The physiological role of KS-WNK1 in the regulation of NCC and potentially other Na(+) transporters in vivo is unknown. Here, we report that mice overexpressing KS-WNK1 in the kidney exhibited renal Na(+) wasting, elevated plasma levels of angiotensin II and aldosterone yet lower blood pressure relative to wild-type littermates. Immunofluorescent staining revealed reduced surface expression of total and phosphorylated NCC and the Na(+)-K(+)-2Cl(-) cotransporter NKCC2 in the distal convoluted tubule and the thick ascending limb of Henle's loop, respectively. Conversely, mice with targeted deletion of exon 4A (the first exon for KS-WNK1) exhibited Na(+) retention, elevated blood pressure on a high-Na(+) diet and increased surface expression of total and phosphorylated NCC and NKCC2 in respective nephron segments. Thus, KS-WNK1 is a negative regulator of NCC and NKCC2 in vivo and plays an important role in the control of Na(+) homeostasis and blood pressure. These results have important implications to the pathogenesis of PHA2 with WNK1 mutations.
Division of Nephrology, Department of Medicine, UT Southwestern Medical Center, Dallas, TX 75390-8856, USA.
Zhen
Z
Liu
Jian
J
Xie
Tao
T
Wu
Thao
T
Truong
Richard J
RJ
Auchus
Chou-Long
CL
Huang
D000595:Amino Acid Sequence; D000818:Animals; D001794:Blood Pressure; D004195:Disease Models, Animal; D015536:Down-Regulation; D005260:Female; D005786:Gene Expression Regulation; D020868:Gene Silencing; D006801:Humans; D007668:Kidney / Q000201:enzymology* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D015778:Minor Histocompatibility Antigens; D008969:Molecular Sequence Data; D009928:Organ Specificity; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011546:Pseudohypoaldosteronism / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D011955:Receptors, Drug / Q000235:genetics* / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D028021:Sodium-Potassium-Chloride Symporters / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D064466:Solute Carrier Family 12, Member 1; D064486:Solute Carrier Family 12, Member 3; D027981:Symporters / Q000235:genetics* / Q000378:metabolism; D000076204:WNK Lysine-Deficient Protein Kinase 1
D015778:Minor Histocompatibility Antigens; D011955:Receptors, Drug; C578714:SLC12A1 protein, human; C578715:Slc12a1 protein, mouse; C578875:Slc12a3 protein, mouse; D028021:Sodium-Potassium-Chloride Symporters; D064466:Solute Carrier Family 12, Member 1; D064486:Solute Carrier Family 12, Member 3; D027981:Symporters; D012964:Sodium; D017346:Protein Serine-Threonine Kinases; D000076204:WNK Lysine-Deficient Protein Kinase 1; C498744:Wnk1 protein, mouse