Cellular distribution of the potassium channel KCNQ1 in normal mouse kidney.
Mechanisms of K(+) secretion and absorption along the collecting duct are not understood fully. Because KCNQ1 participates in K(+) secretion within the inner ear and stomach, distribution of KCNQ1 in mouse kidney was studied using Northern and Western analyses, RT-PCR of isolated tubules, and immunohistochemistry. Northern blots demonstrated KCNQ1 transcripts in whole kidney. RT-PCR showed KCNQ1 mRNA in isolated distal convoluted tubule (DCT), connecting segment (CNT), collecting ducts (CD), and glomeruli. Immunoblots of kidney and stomach revealed a approximately 75-kDa protein, the expected mobility for KCNQ1. KCNQ1 was detected by immunohistochemistry throughout the distal nephron and CD. Thick ascending limbs exhibited weak basolateral immunolabel. In DCT and CNT cells, immunolabel was intense and basolateral, although KCNQ1 label was stronger in late than in early DCT. Initial collecting tubule and cortical CD KCNQ1 immunolabel was predominantly diffuse, but many cells exhibited discrete apical label. Double-labeling experiments demonstrated that principal cells, type B intercalated cells, and a few type A intercalated cells exhibited distinct apical KCNQ1 immunolabel. In inner medullary CD, principal cells exhibited distinct basolateral KCNQ1 immunolabel, whereas intercalated cells showed diffuse cytoplasmic staining. Thus KCNQ1 protein is widely distributed in mouse distal nephron and CD, with significant axial and cellular heterogeneity in location and intensity. These findings suggest that KCNQ1 has cell-specific roles in renal ion transport and may participate in K(+) secretion and/or absorption along the thick ascending limb, DCT, connecting tubule, and CD.
Zheng
Wencui
W
North Florida/South Georgia Veterans Health System, USA.
Verlander
Jill W
JW
Lynch
I Jeanette
IJ
Cash
Melanie
M
Shao
Jiahong
J
Stow
Lisa R
LR
Cain
Brian D
BD
Weiner
I David
ID
Wall
Susan M
SM
Wingo
Charles S
CS
D000818:Animals; D015152:Blotting, Northern; D004847:Epithelial Cells / Q000145:classification / Q000378:metabolism; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D015151:Immunoblotting; D007150:Immunohistochemistry; D051657:KCNQ1 Potassium Channel / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D007684:Kidney Tubules / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D015221:Potassium Channels / Q000378:metabolism; D015347:RNA Probes; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
D051657:KCNQ1 Potassium Channel; C496910:Kcnq1 protein, mouse; D008565:Membrane Proteins; D015221:Potassium Channels; D015347:RNA Probes; D012333:RNA, Messenger; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases