Escherichia coli alpha-hemolysin triggers shrinkage of erythrocytes via K(Ca)3.1 and TMEM16A channels with subsequent phosphatidylserine exposure.
alpha-Hemolysin from Escherichia coli (HlyA) readily lyse erythrocytes from various species. We have recently demonstrated that this pore-forming toxin provokes distinct shrinkage and crenation before it finally leads to swelling and lysis of erythrocytes. The present study documents the underlying mechanism for this severe volume reduction. We show that HlyA-induced shrinkage and crenation of human erythrocytes occur subsequent to a significant rise in [Ca(2+)](i). The Ca(2+)-activated K(+) channel K(Ca)3.1 (or Gardos channel) is essential for the initial shrinkage, because both clotrimazole and TRAM-34 prevent the shrinkage and potentiate hemolysis produced by HlyA. Notably, the recently described Ca(2+)-activated Cl(-) channel TMEM16A contributes substantially to HlyA-induced cell volume reduction. Erythrocytes isolated from TMEM16A(-/-) mice showed significantly attenuated crenation and increased lysis compared with controls. Additionally, we found that HlyA leads to acute exposure of phosphatidylserine in the outer leaflet of the plasma membrane. This exposure was considerably reduced by K(Ca)3.1 antagonists. In conclusion, this study shows that HlyA triggers acute erythrocyte shrinkage, which depends on Ca(2+)-activated efflux of K(+) via K(Ca)3.1 and Cl(-) via TMEM16A, with subsequent phosphatidylserine exposure. This mechanism might potentially allow HlyA-damaged erythrocytes to be removed from the bloodstream by macrophages and thereby reduce the risk of intravascular hemolysis.
Department of Physiology and Biophysics, Aarhus University, 8000 Aarhus, Denmark.
Marianne
M
Skals
Institute of Human Genetics, Aarhus University, and Department of Clinical Genetics, Aarhus University Hospital, 8000 Aarhus, Denmark.
Uffe B
UB
Jensen
Department of Physiology, University of Regensburg, 93053 Regensburg, Germany.
Jiraporn
J
Ousingsawat
Department of Physiology, University of Regensburg, 93053 Regensburg, Germany.
Karl
K
Kunzelmann
Department of Physiology and Biophysics, Aarhus University, 8000 Aarhus, Denmark.
Jens
J
Leipziger
Department of Physiology and Biophysics, Aarhus University, 8000 Aarhus, Denmark. Electronic address: hp@fi.au.dk.
Helle A
HA
Praetorius
D000818:Animals; D000075369:Anoctamin-1; D048429:Cell Size; D002478:Cells, Cultured; D018118:Chloride Channels; D004912:Erythrocytes / Q000187:drug effects*; D029968:Escherichia coli Proteins / Q000494:pharmacology*; D005434:Flow Cytometry; D006460:Hemolysin Proteins / Q000494:pharmacology*; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D008565:Membrane Proteins / Q000187:drug effects* / Q000502:physiology; D051379:Mice; D009363:Neoplasm Proteins / Q000187:drug effects* / Q000502:physiology; D010718:Phosphatidylserines / Q000494:pharmacology*; D024681:Potassium Channels, Calcium-Activated / Q000187:drug effects* / Q000502:physiology
C476213:ANO1 protein, human; D000075369:Anoctamin-1; D018118:Chloride Channels; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D010718:Phosphatidylserines; D024681:Potassium Channels, Calcium-Activated