title: Janus kinase 3 is expressed in erythrocytes, phosphorylated upon energy depletion and involved in the regulation of suicidal erythrocyte death.
abstract: Janus kinase 3, a tyrosine kinase expressed in haematopoetic tissues, plays a decisive role in T-lymphocyte survival. JAK3 deficiency leads to (Severe) Combined Immunodeficiency (SCID) resulting from enhanced lymphocyte apoptosis. JAK3 is activated by phosphorylation. Nothing is known about expression of JAK3 in erythrocytes, which may undergo apoptosis-like cell death (eryptosis) characterized by cell membrane scrambling with phosphatidylserine exposure and cell shrinkage. Triggers of eryptosis include energy depletion. The present study utilized immunohistochemistry and confocal microscopy to test for JAK3 expression and phosphorylation, and FACS analysis to determine phosphatidylserine exposure (annexin binding) and cell volume (forward scatter). As a result, JAK3 was expressed in erythrocytes and phosphorylated following 24h and 48h glucose depletion. Forward scatter was slightly but significantly smaller in erythrocytes from JAK3-deficient mice (jak3(-/-)) than in erythrocytes from wild type mice (jak3(+/+)). Annexin V binding was similarly low in both genotypes. The JAK3 inhibitors WHI-P131/JANEX-1 (4-(4'-Hydroxyphenyl)amino-6,7-dimethoxyquinazoline, 156μM) and WHI-P154 (4-[(3'-Bromo-4'-hydroxyphenyl)amino]-6,7-dimethoxyquinazoline, 11.2μM) did not significantly modify annexin V binding or forward scatter. Glucose depletion increased annexin V binding, an effect significantly blunted in jak3(-/-) erythrocytes and in the presence of the JAK3 inhibitors. The observations disclose a completely novel role of Janus kinase 3, i.e. the triggering of cell membrane scrambling in energy depleted erythrocytes.
authors.affiliation: Department of Physiology, University of Tübingen, Gmelinstrasse 5, Tübingen, Germany.
authors.forename: Shefalee K
authors.initials: SK
authors.lastname: Bhavsar
authors.forename: Shuchen
authors.initials: S
authors.lastname: Gu
authors.forename: Diwakar
authors.initials: D
authors.lastname: Bobbala
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D000255:Adenosine Triphosphate / Q000032:analysis / Q000378:metabolism; D000818:Animals; D017304:Annexin A5 / Q000032:analysis; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D048429:Cell Size; D004906:Erythrocyte Count; D004912:Erythrocytes / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D005260:Female; D005434:Flow Cytometry; D017353:Gene Deletion; D005947:Glucose / Q000172:deficiency / Q000494:pharmacology*; D006801:Humans; D007150:Immunohistochemistry; D053616:Janus Kinase 3 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D010718:Phosphatidylserines / Q000032:analysis / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011799:Quinazolines / Q000494:pharmacology
chemical_list: D017304:Annexin A5; D010718:Phosphatidylserines; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; C116180:WHI P131; C113888:WHI P154; D000255:Adenosine Triphosphate; D053616:Janus Kinase 3; D005947:Glucose