title: Expression of a functional N-methyl-D-aspartate-type glutamate receptor by bone marrow megakaryocytes.
abstract: Better understanding of hemostasis will be possible by the identification of new lineage-specific stimuli that regulate platelet formation. We describe a novel functional megakaryocyte receptor that belongs to a family of ionotropic glutamate receptors of the N-methyl-D-aspartate (NMDA) subtype responsible for synaptic neurotransmission in the central nervous system (CNS). Northern blotting and reverse-transcriptase polymerase chain reaction (RT-PCR) studies identified expression of NMDAR1 and NMDAR2D type subunit mRNA in rat marrow, human megakaryocytes, and MEG-01 clonal megakaryoblastic cells. Immunohistochemistry and in vivo autoradiographic binding of the NMDA receptor-specific antagonist MK-801 confirmed that megakaryocytes expressed open channel-forming NMDA receptors in vivo. Western blots indicated that megakaryocyte NMDAR1 was either unglycosylated or only glycosylated to low levels, and of identical size to CNS-type NMDAR1 after deglycosylation with endoglycosidase F/peptide-N-glycosidase F. In functional studies, we demonstrated that NMDA receptor activity was necessary for phorbol myristate acetate (PMA)-induced differentiation of megakaryoblastic cells; NMDA receptor blockade by specific antagonists significantly inhibited PMA-mediated increases in cell size, CD41 expression, and adhesion of MEG-01 cells. These results provide evidence for a novel pathway by which megakaryocytopoiesis and platelet production may be regulated.
authors.affiliation: Department of Biology, University of York, York, United Kingdom. pg5@york.ac.uk
authors.forename: P G
authors.initials: PG
authors.lastname: Genever
authors.forename: D J
authors.initials: DJ
authors.lastname: Wilkinson
authors.forename: A J
authors.initials: AJ
authors.lastname: Patton
authors.forename: N M
authors.initials: NM
authors.lastname: Peet
authors.forename: Y
authors.initials: Y
authors.lastname: Hong
authors.forename: A
authors.initials: A
authors.lastname: Mathur
authors.forename: J D
authors.initials: JD
authors.lastname: Erusalimsky
authors.forename: T M
authors.initials: TM
authors.lastname: Skerry
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism*; D002478:Cells, Cultured; D002999:Clone Cells; D005312:Fetal Blood / Q000166:cytology; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D007231:Infant, Newborn; D008533:Megakaryocytes / Q000187:drug effects / Q000378:metabolism*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000235:genetics; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D016194:Receptors, N-Methyl-D-Aspartate; D013755:Tetradecanoylphorbol Acetate