title: Piperlongumine-induced phosphatidylserine translocation in the erythrocyte membrane.
abstract: BACKGROUND
  Piperlongumine, a component of Piper longum fruit, is considered as a treatment for malignancy. It is effective by inducing apoptosis. Mechanisms involved in the apoptotic action of piperlongumine include oxidative stress and activation of p38 kinase. In analogy to apoptosis of nucleated cells, erythrocytes may undergo eryptosis, the suicidal death of erythrocytes characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine-exposure at the erythrocyte surface. Signaling involved in eryptosis include increase of cytosolic Ca²⁺-activity ([Ca²⁺]i), formation of ceramide, oxidative stress and activation of p38 kinase.
  
  
  METHODS
  Cell volume was estimated from forward scatter, phosphatidylserine-exposure from annexin V binding, [Ca²⁺]i from Fluo3 fluorescence, reactive oxygen species from 2',7'-dichlorodihydrofluorescein-diacetate fluorescence, and ceramide abundance from binding of fluorescent antibodies in flow cytometry.
  
  
  RESULTS
  A 48 h exposure to piperlongumine (30 µM) was followed by significant decrease of forward scatter and increase of annexin-V-binding. Piperlongumine did not significantly modify [Ca²⁺]i and the effect was not dependent on presence of extracellular Ca²⁺. Piperlongumine significantly increased ROS formation and ceramide abundance.
  
  
  CONCLUSIONS
  Piperlongumine triggers cell membrane scrambling, an effect independent from entry of extracellular Ca²⁺ but at least partially due to ROS and ceramide formation.
authors.affiliation: Department of Physiology, Eberhard-Karls-University of Tuebingen, Gmelinstr. 5, 72076 Tuebingen, Germany. ro.bissinger@gmx.de.
authors.forename: Rosi
authors.initials: R
authors.lastname: Bissinger
authors.affiliation: Department of Physiology, Eberhard-Karls-University of Tuebingen, Gmelinstr. 5, 72076 Tuebingen, Germany. malik.abaid@googlemail.com.
authors.forename: Abaid
authors.initials: A
authors.lastname: Malik
authors.affiliation: Department of Physiology, Eberhard-Karls-University of Tuebingen, Gmelinstr. 5, 72076 Tuebingen, Germany. jamshedwarsi@yahoo.com.
authors.forename: Jamshed
authors.initials: J
authors.lastname: Warsi
authors.affiliation: Department of Physiology, Eberhard-Karls-University of Tuebingen, Gmelinstr. 5, 72076 Tuebingen, Germany. kashif_cbc@yahoo.com.
authors.forename: Kashif
authors.initials: K
authors.lastname: Jilani
authors.affiliation: Department of Physiology, Eberhard-Karls-University of Tuebingen, Gmelinstr. 5, 72076 Tuebingen, Germany. florian.lang@uni-tuebingen.de.
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002518:Ceramides / Q000378:metabolism; D004148:Dioxolanes / Q000494:pharmacology*; D004910:Erythrocyte Membrane / Q000187:drug effects* / Q000378:metabolism; D005452:Fluoresceins / Q000378:metabolism; D006801:Humans; D018384:Oxidative Stress / Q000187:drug effects; D010718:Phosphatidylserines / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D010881:Piperidones
chemical_list: D017304:Annexin A5; D002118:Calcium; D002518:Ceramides; D004148:Dioxolanes; D005452:Fluoresceins; D010718:Phosphatidylserines; D017382:Reactive Oxygen Species; C065013:2',7'-dichlorodihydrofluorescein; C498077:piperlongumine; D010881:Piperidones