title: 15-deoxy-Delta12,14 prostaglandin J2-induced heme oxygenase-1 in megakaryocytes regulates thrombopoiesis.
abstract: BACKGROUND
  Platelet production is an intricate process that is poorly understood. Recently, we demonstrated that the natural peroxisome proliferator-activated receptor gamma (PPARgamma) ligand, 15-deoxy-Delta(12,14) prostaglandin J(2) (15d-PGJ(2)), augments platelet numbers by increasing platelet release from megakaryocytes through the induction of reactive oxygen species (ROS). 15d-PGJ(2) can exert effects independent of PPARgamma, such as increasing oxidative stress. Heme oxygenase-1 (HO-1) is a potent antioxidant and may influence platelet production.
  
  
  OBJECTIVE
  To further investigate the influence of 15d-PGJ(2) on megakaryocytes and to understand whether HO-1 plays a role in platelet production.
  
  
  METHODS
  Meg-01 cells (a primary megakaryoblastic cell line) and primary human megakaryocytes derived from cord blood were used to examine the effects of 15d-PGJ(2) on HO-1 expression in megakaryocytes and their daughter platelets. The role of HO-1 activity in thrombopoiesis was studied using established in vitro models of platelet production.
  
  
  CONCLUSIONS
  15d-PGJ(2) potently induced HO-1 protein expression in Meg-01 cells and primary human megakaryocytes. The platelets produced from these megakaryocytes also expressed elevated levels of HO-1. 15d-PGJ(2)-induced HO-1 was independent of PPARgamma, but could be replicated using other electrophilic prostaglandins, suggesting that the electrophilic properties of 15d-PGJ(2) were important for HO-1 induction. Interestingly, inhibiting HO-1 activity enhanced ROS generation and augmented 15d-PGJ(2)-induced platelet production, which could be attenuated by antioxidants. These new data reveal that HO-1 negatively regulates thrombopoiesis by inhibiting ROS.
authors.affiliation: Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: O'Brien
authors.forename: C J
authors.initials: CJ
authors.lastname: Baglole
authors.forename: T M
authors.initials: TM
authors.lastname: Garcia-Bates
authors.forename: N
authors.initials: N
authors.lastname: Blumberg
authors.forename: C W
authors.initials: CW
authors.lastname: Francis
authors.forename: R P
authors.initials: RP
authors.lastname: Phipps
mesh_terms: D001792:Blood Platelets / Q000166:cytology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D051547:Heme Oxygenase-1 / Q000235:genetics* / Q000502:physiology*; D006801:Humans; D008533:Megakaryocytes / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D015230:Prostaglandin D2 / Q000031:analogs & derivatives* / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors; D034061:Thrombopoiesis / Q000187:drug effects*
chemical_list: C097240:15-deoxy-delta(12,14)-prostaglandin J2; D017382:Reactive Oxygen Species; D051547:Heme Oxygenase-1; D015230:Prostaglandin D2