title: Annexin V staining due to loss of membrane asymmetry can be reversible and precede commitment to apoptotic death.
abstract: Signal-induced apoptosis is a normal phenomenon in which cells respond to changes in their environment through a cascade of intracellular biochemical changes culminating in cell death. However, it is not clear at what point in this process the cell becomes committed to die. An early biochemical change characteristic of cells undergoing apoptosis is the loss of plasma membrane asymmetry, such that high levels of phosphatidylserine become exposed on the outside cell surface. These cells can be recognized by staining with Annexin V, which binds to phosphatidylserine with high affinity. To investigate the mechanisms controlling signal-induced apoptosis we have examined the response of a B cell lymphoma to crosslinking of the membrane immunoglobulin (mIg) receptor. We have found that many of the cells that stain positive for Annexin V are viable and can resume growth and reestablish phospholipid asymmetry once the signal is removed. These results indicate that Annexin V staining, and thus loss of membrane asymmetry, precedes commitment to apoptotic death in this system.
authors.affiliation: Laboratory of Molecular Pathology, Department of Microbiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75235, USA.
authors.forename: A K
authors.initials: AK
authors.lastname: Hammill
authors.forename: J W
authors.initials: JW
authors.lastname: Uhr
authors.forename: R H
authors.initials: RH
authors.lastname: Scheuermann
mesh_terms: D000818:Animals; D017304:Annexin A5 / Q000378:metabolism*; D000906:Antibodies; D017209:Apoptosis / Q000187:drug effects; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D002452:Cell Count; D002462:Cell Membrane / Q000378:metabolism*; D002470:Cell Survival; D008213:Lymphocyte Activation; D051379:Mice; D010718:Phosphatidylserines / Q000378:metabolism; D011419:Propidium; D011940:Receptor Aggregation; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism; D015398:Signal Transduction; D014343:Trypan Blue; D014407:Tumor Cells, Cultured
chemical_list: D017304:Annexin A5; D000906:Antibodies; D010718:Phosphatidylserines; D011947:Receptors, Antigen, B-Cell; D011419:Propidium; D014343:Trypan Blue