Disruption of erythroid K-Cl cotransporters alters erythrocyte volume and partially rescues erythrocyte dehydration in SAD mice.
K-Cl cotransport activity in rbc is a major determinant of rbc volume and density. Pathologic activation of erythroid K-Cl cotransport activity in sickle cell disease contributes to rbc dehydration and cell sickling. To address the roles of individual K-Cl cotransporter isoforms in rbc volume homeostasis, we disrupted the Kcc1 and Kcc3 genes in mice. As rbc K-Cl cotransport activity was undiminished in Kcc1(-/-) mice, decreased in Kcc3(-/-) mice, and almost completely abolished in mice lacking both isoforms, we conclude that K-Cl cotransport activity of mouse rbc is mediated largely by KCC3. Whereas rbc of either Kcc1(-/-) or Kcc3(-/-) mice were of normal density, rbc of Kcc1(-/-)Kcc3(-/-) mice exhibited defective volume regulation, including increased mean corpuscular volume, decreased density, and increased susceptibility to osmotic lysis. K-Cl cotransport activity was increased in rbc of SAD mice, which are transgenic for a hypersickling human hemoglobin S variant. Kcc1(-/-)Kcc3(-/-) SAD rbc lacked nearly all K-Cl cotransport activity and exhibited normalized values of mean corpuscular volume, corpuscular hemoglobin concentration mean, and K(+) content. Although disruption of K-Cl cotransport rescued the dehydration phenotype of most SAD rbc, the proportion of the densest red blood cell population remained unaffected.
Rust
Marco B
MB
Zentrum für Molekulare Neurobiologie Hamburg, Universität Hamburg, Hamburg, Germany.
Alper
Seth L
SL
Rudhard
York
Y
Shmukler
Boris E
BE
Vicente
Rubén
R
Brugnara
Carlo
C
Trudel
Marie
M
Jentsch
Thomas J
TJ
Hübner
Christian A
CA
D000755:Anemia, Sickle Cell / Q000097:blood* / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D004195:Disease Models, Animal; D004911:Erythrocyte Volume; D004912:Erythrocytes / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006451:Hemoglobin, Sickle / Q000235:genetics; D006801:Humans; D017136:Ion Transport; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D027981:Symporters / Q000097:blood / Q000172:deficiency* / Q000235:genetics; D000096922:K Cl- Cotransporters
D017931:DNA Primers; D006451:Hemoglobin, Sickle; D027981:Symporters; D000096922:K Cl- Cotransporters; C492280:Slc12a6 protein, mouse