Mild spherocytosis and altered red cell ion transport in protein 4.2–null mice
Luanne L. Peters, … , David E. Golan, Carlo Brugnara
Luanne L. Peters, … , David E. Golan, Carlo Brugnara
Published June 1, 1999
Citation Information: J Clin Invest. 1999;103(11):1527-1537. https://doi.org/10.1172/JCI5766.
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Article

Mild spherocytosis and altered red cell ion transport in protein 4.2–null mice

Abstract

Protein 4.2 is a major component of the red blood cell (RBC) membrane skeleton. We used targeted mutagenesis in embryonic stem (ES) cells to elucidate protein 4.2 functions in vivo. Protein 4.2–null (4.2–/–) mice have mild hereditary spherocytosis (HS). Scanning electron microscopy and ektacytometry confirm loss of membrane surface in 4.2–/– RBCs. The membrane skeleton architecture is intact, and the spectrin and ankyrin content of 4.2–/– RBCs are normal. Band 3 and band 3–mediated anion transport are decreased. Protein 4.2–/– RBCs show altered cation content (increased K+/decreased Na+)resulting in dehydration. The passive Na+ permeability and the activities of the Na-K-2Cl and K-Cl cotransporters, the Na/H exchanger, and the Gardos channel in 4.2–/– RBCs are significantly increased. Protein 4.2–/– RBCs demonstrate an abnormal regulation of cation transport by cell volume. Cell shrinkage induces a greater activation of Na/H exchange and Na-K-2Cl cotransport in 4.2–/– RBCs compared with controls. The increased passive Na+ permeability of 4.2–/– RBCs is also dependent on cell shrinkage. We conclude that protein 4.2 is important in the maintenance of normal surface area in RBCs and for normal RBC cation transport.

Authors

Luanne L. Peters, Hitesh K. Jindel, Babette Gwynn, Cathy Korsgren, Kathryn M. John, Samuel E. Lux, Narla Mohandas, Carl M. Cohen, Michael R. Cho, David E. Golan, Carlo Brugnara

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Figure 3

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Partial band 3 deficiency in 4.2–/– RBCs. (a) Western blots demonstratin...
Partial band 3 deficiency in 4.2–/– RBCs. (a) Western blots demonstrating immunoreactive α- and β-spectrin (Sp; top 2 arrows, respectively), band 3 (Bd 3), ankyrin (Ank), protein 4.1 (4.1), p55, and glycophorin C (GPC) in normal (+/+) and 4.2-null (–/–) RBC membrane ghosts. p55 and GPC were detected using chemiluminescence; Sp, Bd 3, Ank, and protein 4.1 were detected using alkaline phosphatase–labeled secondary antibody. Each lane contains either equivalent amounts of ghost proteins (5 μg: bd 3 and 4.1; 20 μg: p55 and GPC) or cells (5 × 107 total cells: Sp and Ank). Note the decrement in band 3 in null (–/–) vs. normal (+/+) RBC membrane ghosts. (b) The maximal inhibitory DIDS concentration in 4.2–/– RBCs is decreased to ∼70% of 4.2+/+, confirming reduction of band 3. (c) Red blood cell anion transport. DIDS-sensitive sulfate transport (X ± SEM) in 4.2–/– and 4.2+/– RBCs is decreased to ∼ 60% and ∼80%, respectively, of 4.2+/+ RBCs. *P < 0.05 vs. 4.2+/+. **P < 0.01 vs. 4.2+/+.