The objectives of this project are to define and characterize molecular evens of megakaryocytopoiesis and platelet production by analyzing the in vivo expression of platelet glycoprotein (GP) receptors. Our studies target the GP Ib-IX-V complex, a membrane multi subunit receptor providing platelets with two properties essential for normal function. First, GP Ib-IX-V supports platelet adhesion on thrombogenic surfaces, a process exemplified by bleeding disorders which result from a congenital absence of the receptor or its ligand, von Willerbrand factor. Second, is an assumed role for GP Ib-IX-V in normal platelet morphogenesis, suggested by the release of abnormal giant platelets coinciding with the congenital absence of the receptor, the Bernard- Soulier syndrome. However, the mechanisms responsible for platelet release from the megakaryocyte and the maintenance of a normal structure of recirculating platelets are poorly understood primarily due to the lack of in vitro models to examine and manipulate either process. A distinctive feature of this proposal is the utilization of in vivo models to examine platelet receptor expression in the unique intracellular environment of the megakaryocyte and platelet. Proposed studies will provide fundamental information on the mechanisms of in vivo regulation of GP Ib supporting a long-term objective of defining molecular events and/or factors responsible for the transcription of megakaryocytic-specific genes (Aims 1 and 2). Other experiments will evaluate the expression of septin genes during megakaryocytopoiesis. These have been made possible by the identification of human septin genes expressed by megakaryocytes, which are directly linked to the expression of the beta-subunit of GP Ib (Aim 3). We will also test the structural hypothesis linking platelet GP Ib-IX-V expression to normal platelet structure by proposing experiments to examine the in vivo relevance of interactions between the cytoplasmic domain of the alpha- subunit of GP Ib and the platelet membrane cytoskeleton in a murine model of the Bernard-Soulier syndrome (Aim 4).
These aims will be achieved through the combined use of megakaryocytic-specific gene promoters, the expression of variant GP Ibalpha molecules on the surface of murine blood platelets, and an examination of in vivo and in vitro megakaryocytic gene expression. These studies will generate basic information that can be applied to therapeutic strategies for pathological conditions affecting megakaryocytopoiesis and platelet production.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
2R01HL050545-05
Application #
2631792
Study Section
Hematology Subcommittee 2 (HEM)
Project Start
1994-05-01
Project End
2002-04-30
Budget Start
1998-05-01
Budget End
1999-04-30
Support Year
5
Fiscal Year
1998
Total Cost
Indirect Cost
Name
Scripps Research Institute
Department
Type
DUNS #
City
La Jolla
State
CA
Country
United States
Zip Code
92037
Franco, Aime T; Corken, Adam; Ware, Jerry (2015) Platelets at the interface of thrombosis, inflammation, and cancer. Blood 126:582-8
Corken, Adam; Russell, Susan; Dent, Judith et al. (2014) Platelet glycoprotein Ib-IX as a regulator of systemic inflammation. Arterioscler Thromb Vasc Biol 34:996-1001
Kanaji, S; Fahs, S A; Ware, J et al. (2014) Non-myeloablative conditioning with busulfan before hematopoietic stem cell transplantation leads to phenotypic correction of murine Bernard-Soulier syndrome. J Thromb Haemost 12:1726-32
Boulaftali, Yacine; Hess, Paul R; Getz, Todd M et al. (2013) Platelet ITAM signaling is critical for vascular integrity in inflammation. J Clin Invest 123:908-16
Joglekar, M V; Ware, Jerry; Xu, Jin et al. (2013) Platelets, glycoprotein Ib-IX, and von Willebrand factor are required for FeCl(3)-induced occlusive thrombus formation in the inferior vena cava of mice. Platelets 24:205-12
Ware, Jerry; Corken, Adam; Khetpal, Reshma (2013) Platelet function beyond hemostasis and thrombosis. Curr Opin Hematol 20:451-6
Yin, Hong; Stojanovic-Terpo, Aleksandra; Xu, Weidong et al. (2013) Role for platelet glycoprotein Ib-IX and effects of its inhibition in endotoxemia-induced thrombosis, thrombocytopenia, and mortality. Arterioscler Thromb Vasc Biol 33:2529-37
Kanaji, Taisuke; Ware, Jerry; Okamura, Takashi et al. (2012) GPIb? regulates platelet size by controlling the subcellular localization of filamin. Blood 119:2906-13
Boilard, Eric; Larabee, Katherine; Shnayder, Ruslan et al. (2011) Platelets participate in synovitis via Cox-1-dependent synthesis of prostacyclin independently of microparticle generation. J Immunol 186:4361-6
Boilard, Eric; Nigrovic, Peter A; Larabee, Katherine et al. (2010) Platelets amplify inflammation in arthritis via collagen-dependent microparticle production. Science 327:580-3

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