Expression of HbC and HbS, but not HbA, results in activation of K-Cl cotransport activity in transgenic mouse red cells

Romero, José R.; Suzuka, Sandra M.; Nagel, Ronald L.; Fabry, Mary E.

doi:10.1182/blood-2003-01-0237

Cited by 22 publications

(21 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Positively charged Hb S and Hb C are associated with dehydration via up-regulation of the KCl cotransporter. [43][44][45] Notably, diffuse Hb strains would be predicted to have increased positive charge relative to single strains because ␤ dminor has a net loss of 2 negative residues, resulting in a pI of 7.85 versus 7.13 in ␤ S/T and ␤ dmajor . Whether this translates into a corresponding increase in KCl cotransport activity awaits further study.…”

Section: Discussionmentioning

confidence: 99%

Sequence variation at multiple loci influences red cell hemoglobin concentration

Peters

Shavit²,

Lambert

et al. 2010

Blood

View full text Add to dashboard Cite

A substantial genetic contribution underlies variation in baseline peripheral blood counts. We performed quantitative trait locus/loci analyses to identify chromosome regions harboring genes influencing red cell hemoglobin concentration using the cell hemoglobin concentration mean (CHCM), a directly measured parameter analogous to the mean cell hemoglobin concentration. Fourteen significant loci (gene symbols Chcmq1-Chcmq14) were detected. Seven of these influenced CHCM in a sex-specific fashion, and 2 showed significant interactive effects (epistasis). For quantitative trait locus/ loci detected in multiple crosses, confidence intervals were narrowed using statistical and bioinformatic approaches. Two strong candidate genes emerged and were further analyzed: adult ␤-globin (Hbb) for

show abstract

Section: Discussionmentioning

confidence: 99%

Sequence variation at multiple loci influences red cell hemoglobin concentration

Peters

Shavit²,

Lambert

et al. 2010

Blood

View full text Add to dashboard Cite

show abstract

“…5,6 Expression of Hb S or C in transgenic mice also increases red cell KCC activity. 7 Recently, we demonstrated an abnormal response to acid pH in SS RBCs that was partially corrected by incubation with the sulfhydryl reducing agent, dithiothreitol. 8 These findings suggested that regulation of KCC is abnormal in SS RBCs.…”

Section: Introductionmentioning

confidence: 99%

“…7,11,12 However, these studies, like flux studies, are complicated by varying numbers of reticulocytes (or young cells) in unfractionated SS blood, which preclude comparisons of KCC-mediated volume reduction in SS and AA cells. We recently compared the RVD mediated by KCC and stimulated by cell swelling and acid pH in SS and AA reticulocytes by tracking the changes in reticulocyte CHC by means of density gradient analysis.…”

Section: Introductionmentioning

confidence: 99%

Urea stimulation of KCl cotransport induces abnormal volume reduction in sickle reticulocytes

Joiner

Rettig

Jiang

et al. 2006

Blood

View full text Add to dashboard Cite

KCl cotransport (KCC) activity contributes to pathologic dehydration in sickle (SS) red blood cells (RBCs). KCC activation by urea was measured in SS and IntroductionThe KCl cotransporter (KCC) mediates electroneutral coupled transport of K ϩ and Cl Ϫ in a variety of cell types. 1,2 KCC activation results in net efflux of KCl from cells with high potassium content, with accompanying water loss and volume reduction. KCC is active in reticulocytes and diminishes with red cell maturation. 3,4 It is thought to function physiologically to reduce red blood cell (RBC) volume and establish the high cellular hemoglobin concentration (CHC) characteristic of mature cells. KCC is activated in vitro by cell swelling, acid pH, sulfhydryl oxidation/alkylation, and exposure to urea, but the relative importance of these stimuli in vivo is unknown.In RBCs containing sickle hemoglobin (Hb S), KCC activity is high, in part because of the high percentage of reticulocytes. 4 However, Hb S or Hb C in trait RBCs (AS or AC) with normal mean cell age, or after incorporation into normal RBC ghosts, appears to increase KCC activity. 5,6 Expression of Hb S or C in transgenic mice also increases red cell KCC activity. 7 Recently, we demonstrated an abnormal response to acid pH in SS RBCs that was partially corrected by incubation with the sulfhydryl reducing agent, dithiothreitol. 8 These findings suggested that regulation of KCC is abnormal in SS RBCs.As a volume regulator, KCC activity is responsive to CHC. 9,10 KCC is activated on cell swelling, and, as KCl is lost, cell volume falls, cellular hemoglobin concentration increases, and transport activity diminishes. The resultant CHC thus reflects the physiologic "volume set point" of the system. The inactivation of KCC as the cell shrinks toward its new steady state is most likely a key factor in defining the volume regulatory function of the transporter, which in turn is crucial for establishing the steady state CHC for RBCs in vivo.Volume reduction mediated by KCC has been demonstrated with RBC density measurements. 7,11,12 However, these studies, like flux studies, are complicated by varying numbers of reticulocytes (or young cells) in unfractionated SS blood, which preclude comparisons of KCC-mediated volume reduction in SS and AA cells. We recently compared the RVD mediated by KCC and stimulated by cell swelling and acid pH in SS and AA reticulocytes by tracking the changes in reticulocyte CHC by means of density gradient analysis. 8 Acid-stimulated volume reduction was exaggerated in SS reticulocytes and was diminished by sulfhydryl reduction, parallel to the behavior of KCC flux activity. However, despite the normal response of KCC flux activation to cell swelling in SS RBCs, swelling-stimulated volume reduction was markedly abnormal in SS reticulocytes and resulted in higher final CHC than in AA reticulocytes. Thus, volume reduction and KCC fluxes appear to reflect different functional aspects of the KCC system in RBCs and may be subject to different pathologic influences in SS RBCs...

show abstract

“…The C57 (background) mouse and full KO mice models expressing HbE and HbS or HbA are used as controls. In selective cases, the HbA full KO mouse model is compared but found to be limited due to its RBC thalassemic characteristics [37] [38]. …”

Section: Introductionmentioning

confidence: 99%

A transgenic mouse model expressing exclusively human hemoglobin E: Indications of a mild oxidative stress

Fabry

Rybicki

Suzuka

et al. 2012

Blood Cells, Molecules, and Diseases

Self Cite

View full text Add to dashboard Cite

Hemoglobin (Hb) E (β26 Glu→ Lys) is the most common abnormal hemoglobin (Hb) variant in the world. Homozygotes for HbE are mildly thalassemic as a result of the alternate splice mutation and present with a benign clinical picture (microcytic and mildly anemic) with rare clinical symptoms. Given that the human red blood cell (RBC) contains both HbE and excess α-chains along with minor hemoglobins, the consequence of HbE alone on RBC pathophysiology has not been elucidated. This becomes critical for the highly morbid βE-thalassemia disease. We have generated transgenic mice exclusively expressing human HbE (HbEKO) that exhibit the known aberrant splicing of βE globin mRNA, but are essentially non-thalassemic as demonstrated by RBC α/β (human) globin chain synthesis. These mice exhibit hematological characteristics similar to presentations in human EE individuals: microcytic RBC with low MCV and MCH but normal MCHC; target RBC; mild anemia with low Hb, HCT and mildly elevated reticulocyte levels and decreased osmotic fragility, indicating altered RBC surface area to volume ratio. These alterations are correlated with a mild RBC oxidative stress indicated by enhanced membrane lipid peroxidation, elevated zinc protoporphyrin levels, and by small but significant changes in cardiac function. The C57 (background) mouse and full KO mouse models expressing HbE with the presence of HbS or HbA are used as controls. In select cases, the HbA full KO mouse model is compared but found to be limited due to its RBC thalassemic characteristics. Since the HbEKO mouse RBC lacks an abundance of excess α-chains that would approximate a mouse thalassemia (or a human thalassemia), the results indicate that the observed in vivo RBC mild oxidative stress arises, at least in part, from the molecular consequences of the HbE mutation.

show abstract

Expression of HbC and HbS, but not HbA, results in activation of K-Cl cotransport activity in transgenic mouse red cells

Abstract: Elevation of K-

Cited by 22 publications

References 49 publications

Sequence variation at multiple loci influences red cell hemoglobin concentration

Sequence variation at multiple loci influences red cell hemoglobin concentration

Urea stimulation of KCl cotransport induces abnormal volume reduction in sickle reticulocytes

A transgenic mouse model expressing exclusively human hemoglobin E: Indications of a mild oxidative stress

Contact Info

Product

Resources

About