1
|
Frumence E, Genetet S, Ripoche P, Iolascon A, Andolfo I, Le Van Kim C, Colin Y, Mouro-Chanteloup I, Lopez C. Rapid Cl−/HCO3−exchange kinetics of AE1 in HEK293 cells and hereditary stomatocytosis red blood cells. Am J Physiol Cell Physiol 2013; 305:C654-62. [DOI: 10.1152/ajpcell.00142.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Anion exchanger 1 (AE1) or band 3 is a membrane protein responsible for the rapid exchange of chloride for bicarbonate across the red blood cell membrane. Nine mutations leading to single amino-acid substitutions in the transmembrane domain of AE1 are associated with dominant hereditary stomatocytosis, monovalent cation leaks, and reduced anion exchange activity. We set up a stopped-flow spectrofluorometry assay coupled with flow cytometry to investigate the anion transport and membrane expression characteristics of wild-type recombinant AE1 in HEK293 cells, using an inducible expression system. Likewise, study of three stomatocytosis-associated mutations (R730C, E758K, and G796R), allowed the validation of our method. Measurement of the rapid and specific chloride/bicarbonate exchange by surface expressed AE1 showed that E758K mutant was fully active compared with wild-type (WT) AE1, whereas R730C and G796R mutants were inactive, reinforcing previously reported data on other experimental models. Stopped-flow analysis of AE1 transport activity in red blood cell ghost preparations revealed a 50% reduction of G796R compared with WT AE1 corresponding to a loss of function of the G796R mutated protein, in accordance with the heterozygous status of the AE1 variant patients. In conclusion, stopped-flow led to measurement of rapid transport kinetics using the natural substrate for AE1 and, conjugated with flow cytometry, allowed a reliable correlation of chloride/bicarbonate exchange to surface expression of AE1, both in recombinant cells and ghosts and therefore a fine comparison of function between different stomatocytosis samples. This technical approach thus provides significant improvements in anion exchange analysis in red blood cells.
Collapse
Affiliation(s)
- Etienne Frumence
- Inserm U665, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, UMR-S665, Paris, France
- Institut National de la Transfusion Sanguine, Paris, France
- Laboratoire d'Excellence GR-Ex., Paris, France
- Université de la Réunion, Saint-Denis, France; and
| | - Sandrine Genetet
- Inserm U665, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, UMR-S665, Paris, France
- Institut National de la Transfusion Sanguine, Paris, France
- Laboratoire d'Excellence GR-Ex., Paris, France
| | - Pierre Ripoche
- Inserm U665, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, UMR-S665, Paris, France
- Institut National de la Transfusion Sanguine, Paris, France
- Laboratoire d'Excellence GR-Ex., Paris, France
| | - Achille Iolascon
- Chair of Medical Genetics, Department of Molecular Medicine and Medical Biotechnologies, University Federico II, Naples, and CEINGE-Advanced Biotechnologies, Naples, Italy
| | - Immacolata Andolfo
- Chair of Medical Genetics, Department of Molecular Medicine and Medical Biotechnologies, University Federico II, Naples, and CEINGE-Advanced Biotechnologies, Naples, Italy
| | - Caroline Le Van Kim
- Inserm U665, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, UMR-S665, Paris, France
- Institut National de la Transfusion Sanguine, Paris, France
- Laboratoire d'Excellence GR-Ex., Paris, France
| | - Yves Colin
- Inserm U665, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, UMR-S665, Paris, France
- Institut National de la Transfusion Sanguine, Paris, France
- Laboratoire d'Excellence GR-Ex., Paris, France
| | - Isabelle Mouro-Chanteloup
- Inserm U665, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, UMR-S665, Paris, France
- Institut National de la Transfusion Sanguine, Paris, France
- Laboratoire d'Excellence GR-Ex., Paris, France
| | - Claude Lopez
- Inserm U665, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, UMR-S665, Paris, France
- Institut National de la Transfusion Sanguine, Paris, France
- Laboratoire d'Excellence GR-Ex., Paris, France
| |
Collapse
|