title: Enhanced eryptosis following juglone exposure.
abstract: Juglone, a quinone isolated from Juglans mandshurica Maxim, has previously been shown to be effective against malignancy. The effect is at least partially due to stimulation of suicidal death or apoptosis of tumour cells. On the other hand, juglone has been shown to counteract apoptosis, for example, of neurons. In analogy to apoptosis of nucleated cells, erythrocytes may enter eryptosis, a suicidal death characterized by cell shrinkage and breakdown of phosphatidylserine asymmetry of the cell membrane with phosphatidylserine exposure at the erythrocyte surface. Stimulators of eryptosis include increase in cytosolic Ca(2+) activity [(Ca(2+) )i]. This study explored whether juglone stimulates eryptosis. To this end, erythrocyte volume was estimated from forward scatter, phosphatidylserine exposure at the erythrocyte surface from FITC annexin V binding, ceramide abundance from binding of fluorescent antibodies in flow cytometry and cytosolic ATP with a luciferin-luciferase-based assay. As a result, a 24-hr exposure of human erythrocytes to juglone (5 μM) significantly decreased erythrocyte forward scatter. Juglone (1-5 μM) significantly increased the percentage of annexin V binding cells. Juglone (5 μM) significantly increased ceramide abundance at the erythrocyte surface and decreased erythrocyte ATP concentration. The effect of juglone (10 μM) on annexin V binding was slightly but significantly blunted by removal of extracellular Ca(2+) and by addition of protein kinase C (PKC) inhibitor staurosporine (1 μM). In conclusion, juglone stimulates suicidal erythrocyte death or eryptosis at least in part by upregulation of ceramide abundance, energy depletion and activation of PKC.
authors.affiliation: Department of Physiology, University of Tuebingen, Tuebingen, Germany; Department of Biological and Environmental Sciences, University of Messina, S. Agata-Messina, Italy.
authors.forename: Salvatrice
authors.initials: S
authors.lastname: Calabrò
authors.forename: Kousi
authors.initials: K
authors.lastname: Alzoubi
authors.forename: Rosi
authors.initials: R
authors.lastname: Bissinger
authors.forename: Kashif
authors.initials: K
authors.lastname: Jilani
authors.forename: Caterina
authors.initials: C
authors.lastname: Faggio
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D000255:Adenosine Triphosphate / Q000097:blood; D017304:Annexin A5 / Q000378:metabolism; D000972:Antineoplastic Agents, Phytogenic / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000097:blood; D048429:Cell Size / Q000187:drug effects; D002518:Ceramides / Q000097:blood; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D009285:Naphthoquinones / Q000633:toxicity*; D010718:Phosphatidylserines / Q000097:blood
chemical_list: D017304:Annexin A5; D000972:Antineoplastic Agents, Phytogenic; D002518:Ceramides; D009285:Naphthoquinones; D010718:Phosphatidylserines; D000255:Adenosine Triphosphate; D002118:Calcium; C005134:juglone