Sulphydryl modifications alter scramblase activity in murine sickle cell disease.
Increased oxidant stress has been suggested to play a role in the process of phosphatidylserine (PS) externalization in the red blood cells of sickle cell patients. Inhibition of the ATP-driven translocation from outer to inner monolayer (flippase) by sulphydryl modification has been established. The present study showed that phospholipid scrambling was also sensitive to protein sulphydryl modification. Treatment with N-ethylmaleimide lead to enhanced PS exposure and a lower Ca(++) requirement for scrambling. In contrast, pyridyldithioethylamine treatment inhibited PS exposure. Red blood cells from a murine model for sickle cell disease exhibited a reduced response to both reagents, suggestive of previous sulphydryl modifications to the protein(s) involved in phospholipid scrambling. We conclude that sulphydryl modifications to both scramblase and flippase underlie the enhanced formation of PS-exposing cells in sickle cell disease.
de Jong
Kitty
K
Children's Hospital Oakland Research Institute, Oakland, CA 94609, USA. kdejong@chori.org
Kuypers
Frans A
FA
D000755:Anemia, Sickle Cell / Q000097:blood*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004910:Erythrocyte Membrane / Q000378:metabolism; D004912:Erythrocytes / Q000187:drug effects; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018384:Oxidative Stress; D010718:Phosphatidylserines / Q000097:blood; D049294:Phospholipid Transfer Proteins / Q000037:antagonists & inhibitors / Q000097:blood* / Q000502:physiology; D013438:Sulfhydryl Compounds / Q000097:blood*
D010718:Phosphatidylserines; D049294:Phospholipid Transfer Proteins; D013438:Sulfhydryl Compounds; D002118:Calcium