Expression of a Functional N-Methyl-d-Aspartate–Type Glutamate Receptor by Bone Marrow Megakaryocytes

• Published in: Blood Vol. 93; no. 9; pp. 2876 - 2883
• Main Authors: Genever, Paul G., Wilkinson, David J.P., Patton, Amanda J., Peet, Nicky M., Hong, Ying, Mathur, Anthony, Erusalimsky, Jorge D., Skerry, Tim M.
• Format: Journal Article
• Language: English
• Published: 01.05.1999
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V93.9.2876.409k31_2876_2883

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 theN-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.