Erythrocyte ion content and dehydration modulate maximal Gardos channel activity in KCNN4 V282M/+ hereditary xerocytosis red cells

Author:

Rivera Alicia1,Vandorpe David H.1,Shmukler Boris E.1,Andolfo Immacolata2,Iolascon Achille2,Archer Natasha M.3,Shabani Estela4,Auerbach Michael5,Hamerschlak Nelson6,Morton James7,Wohlgemuth Jay G.7,Brugnara Carlo8,Snyder L. Michael910,Alper Seth L.111

Affiliation:

1. Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts

2. Department of Molecular Medicine and Medical Biotechnologies, “Federico II” University of Naples, CEINGE Biotecnologie Avanzate, Naples, Italy

3. Division of Hematology and Oncology, Boston Children’s Hospital, Dana-Farber Cancer Center, Department of Pediatrics, Harvard Medical School, Boston, Massachusetts

4. Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts

5. Auerbach Hematology-Oncology, Rosedale, Maryland

6. Department of Hematology, Hospital Israelita Albert Einstein, Sao Paulo, Brazil

7. Quest Diagnostics, San Juan Capistrano, California

8. Department of Laboratory Medicine, Boston Children’s Hospital and Department of Pathology, Harvard Medical School, Boston, Massachusetts

9. Quest Diagnostics, Marlborough, Massachusetts

10. Departments of Medicine and Laboratory Medicine, University of Massachusetts Medical Center, Worcester, Massachusetts

11. Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts

Abstract

Hereditary xerocytosis (HX) is caused by missense mutations in either the mechanosensitive cation channel PIEZO1 or the Ca2+-activated K+channel KCNN4. All HX-associated KCNN4 mutants studied to date have revealed increased current magnitude and red cell dehydration. Baseline KCNN4 activity was increased in HX red cells heterozygous for KCNN4 mutant V282M. However, HX red cells maximally stimulated by Ca2+ionophore A23187 or by PMCA Ca2+-ATPase inhibitor orthovanadate displayed paradoxically reduced KCNN4 activity. This reduced Ca2+-stimulated mutant KCNN4 activity in HX red cells was associated with unchanged sensitivity to KCNN4 inhibitor senicapoc and KCNN4 activator Ca2+, with slightly elevated Ca2+uptake and reduced PMCA activity, and with decreased KCNN4 activation by calpain inhibitor PD150606. The altered intracellular monovalent cation content of HX red cells prompted experimental nystatin manipulation of red cell Na and K contents. Nystatin-mediated reduction of intracellular K+with corresponding increase in intracellular Na+in wild-type cells to mimic conditions of HX greatly suppressed vanadate-stimulated and A23187 -stimulated KCNN4 activity in those wild-type cells. However, conferral of wild-type cation contents on HX red cells failed to restore wild-type-stimulated KCNN4 activity to those HX cells. The phenotype of reduced, maximally stimulated KCNN4 activity was shared by HX erythrocytes expressing heterozygous PIEZO1 mutants R2488Q and V598M, but not by HX erythrocytes expressing heterozygous KCNN4 mutant R352H or PIEZO1 mutant R2456H. Our data suggest that chronic KCNN4-driven red cell dehydration and intracellular cation imbalance can lead to reduced KCNN4 activity in HX and wild-type red cells.

Funder

QUEST Diagnostics

Publisher

American Physiological Society

Subject

Cell Biology,Physiology

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