title: P2Y12 protects platelets from apoptosis via PI3k-dependent Bak/Bax inactivation.
abstract: BACKGROUND
  Platelet ADP receptor P2Y(12) is well studied and recognized as a key player in platelet activation, hemostasis and thrombosis. However, the role of P2Y(12) in platelet apoptosis remains unknown.
  
  
  OBJECTIVE
  To evaluate the role of the P2Y(12) receptor in platelet apoptosis.
  
  
  METHODS
  We used flow cytometry and Western blotting to assess apoptotic events in platelets treated with ABT-737 or ABT-263, and stored at 37°C, combined with P2Y(12) receptor antagonists or P2Y(12) -deficient mice.
  
  
  RESULTS
  P2Y(12) activation attenuated apoptosis induced by ABT-737 in human and mouse platelets in vitro, evidenced by reduced phosphatidylserine (PS) exposure, diminished depolarization of mitochondrial inner transmembrane potential (ΔΨm) and decreased caspase-3 activation. Through increasing the phosphorylation level of Akt and Bad, and changing the interaction between different Bcl-2 family proteins, P2Y(12) activation inactivated Bak/Bax. This antiapoptotic effect could be abolished by P2Y(12) antagonism or PI3K inhibition. We also observed the antiapoptotic effect of P2Y(12) activation in platelets stored at 37°C. P2Y(12) activation improved the impaired activation responses of apoptotic platelets stressed by ABT-737. In platelets from mice dosed with ABT-263 in vivo, clopidogrel or deficiency of P2Y(12) receptor enhanced apoptosis along with increased Bak/Bax activation.
  
  
  CONCLUSIONS
  This study demonstrates that P2Y(12) activation protects platelets from apoptosis via PI3k-dependent Bak/Bax inactivation, which may be physiologically important to counter the proapoptotic challenge. Our findings that P2Y(12) blockade exaggerates platelet apoptosis induced by ABT-263 (Navitoclax) also imply a novel drug interaction of ABT-263 and P2Y(12) antagonists.
authors.affiliation: Key Laboratory of Molecular Medicine, Ministry of Education, and Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai, China.
authors.forename: S
authors.initials: S
authors.lastname: Zhang
authors.forename: J
authors.initials: J
authors.lastname: Ye
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: X
authors.initials: X
authors.lastname: Xu
authors.forename: J
authors.initials: J
authors.lastname: Liu
authors.forename: S H
authors.initials: SH
authors.lastname: Zhang
authors.forename: S P
authors.initials: SP
authors.lastname: Kunapuli
authors.forename: Z
authors.initials: Z
authors.lastname: Ding
mesh_terms: D000814:Aniline Compounds / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001713:Biphenyl Compounds / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects* / Q000201:enzymology* / Q000473:pathology; D015153:Blotting, Western; D053148:Caspase 3 / Q000097:blood; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D006801:Humans; D053078:Membrane Potential, Mitochondrial; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009596:Nitrophenols / Q000494:pharmacology; D058539:Phosphatidylinositol 3-Kinase / Q000097:blood*; D010718:Phosphatidylserines / Q000097:blood; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000097:blood; D058921:Purinergic P2Y Receptor Antagonists / Q000494:pharmacology; D058925:Receptors, Purinergic P2Y12 / Q000097:blood* / Q000172:deficiency / Q000187:drug effects / Q000235:genetics; D015398:Signal Transduction; D013449:Sulfonamides / Q000494:pharmacology; D013997:Time Factors; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000097:blood*; D051028:bcl-2-Associated X Protein / Q000097:blood*; D051025:bcl-Associated Death Protein / Q000097:blood
chemical_list: C501332:ABT-737; D000814:Aniline Compounds; C494819:BAD protein, human; C494772:BAK1 protein, human; C494826:BAX protein, human; C494820:Bad protein, mouse; C494773:Bak1 protein, mouse; C494827:Bax protein, mouse; D001713:Biphenyl Compounds; D009596:Nitrophenols; C548576:P2RY12 protein, human; C548577:P2ry12 protein, mouse; D010718:Phosphatidylserines; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D058921:Purinergic P2Y Receptor Antagonists; D058925:Receptors, Purinergic P2Y12; D013449:Sulfonamides; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D051025:bcl-Associated Death Protein; D058539:Phosphatidylinositol 3-Kinase; D051057:Proto-Oncogene Proteins c-akt; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; C528561:navitoclax