We have a longstanding research interest into the molecular basis of inherited platelet dysfunction. Transcription factor RUNX1 is a master regulator of hematopoiesis, megakaryopoiesis and thrombopoiesis. The overall goal of this project is to obtain insights into the molecular basis of the platelet dysfunction associated with human RUNX1 mutations and into the genes regulated by it in platelets/megakaryocytes (MK) through studies in patients with RUNX1 haplodeficiency (RHD), characterized by familial thrombocytopenia, platelet dysfunction and a predisposition to acute leukemia. They have abnormalities in platelet granules and impaired platelet responses. Our platelet expression profiling of a RHD patient, one of the first platelet profiling studies in a patient with inherited platelet dysfunction, showed several genes are down regulated, some are direct RUNX1 targets, and affect specific aspects of platelet/MK biology. RHD is an important human model and untapped reservoir of information into platelet/ MK biology. Studies supported by the current R01 Award have been highly successful and extend the relevance of RUNX1 regulation of genes from bleeding disorder to CV disease. We propose studies on the RUNX1 regulation of 2 genes whose expression is decreased in RHD platelets: coagulation factor XIIIa (gene F13A) and phosphodiesterase E5A (PDE5A); little is known regarding their regulation.
Aim 1 is to study the mechanisms and effects of decreased MK/platelet expression of F13A and PDE5A in RHD. F13A is synthesized by MK, (~3% of platelet protein) and regulates clot retraction. PDE5A regulates cGMP levels, a major regulator of platelet responses. We will perform studies in RHD patient platelets and in cultured cells, (HEL cells and MK generated from IPSCs from a RHD patient). We will assess association of RUNX1 regulation of these genes in vivo and in relation to future death and MI in patients with heart disease. RUNX1 is expressed from two alternate promoters ? a distal P1 and a proximal P2 promoter, leading to two distinct proteins, RUNX1C and RUNX1B, with differential effects.
Aim 2 is to study the differential regulation of MK/platelet genes by the RUNX1B and RUNX1C. Recent evidence suggests that RUNX1C is autoregulated by RUNX1.
Aim 3 is to study the autoregulation of RUNX1 by RUNX1B and RUNX1C. Our studies will provide important, new information into the aberrant platelet/MK mechanisms in RHD, the differential gene regulation by RUNX1 variants and their downstream effects, and the relationship to CV disease. They will lay the basis for developing newer antithrombotic strategies.

Public Health Relevance

Platelets are tiny blood cells that play a role in stopping bleeding following injury and in the formation of clots that cause heart attacks. Our longstanding goals are to define the molecular mechanisms in platelets and megakaryocytes through the studies in a group of poorly understood patients with defective platelets and bleeding symptoms. This project will provide new insights into platelet mechanisms and form the basis for new therapies for cardiovascular diseases and bleeding disorders.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL109568-07
Application #
10083753
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Sarkar, Rita
Project Start
2013-01-18
Project End
2022-11-30
Budget Start
2020-12-01
Budget End
2021-11-30
Support Year
7
Fiscal Year
2021
Total Cost
Indirect Cost
Name
Temple University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
057123192
City
Philadelphia
State
PA
Country
United States
Zip Code
19122
Jalagadugula, Gauthami; Goldfinger, Lawrence E; Mao, Guangfen et al. (2018) Defective RAB1B-related megakaryocytic ER-to-Golgi transport in RUNX1 haplodeficiency: impact on von Willebrand factor. Blood Adv 2:797-806
Mao, G F; Goldfinger, L E; Fan, D C et al. (2017) Dysregulation of PLDN (pallidin) is a mechanism for platelet dense granule deficiency in RUNX1 haplodeficiency. J Thromb Haemost 15:792-801
Rao, A Koneti (2017) Editorial: Platelet Genomics and Disorders of Platelet Number and Function. Platelets 28:2
Rao, A Koneti; Songdej, Natthapol (2017) Parsing the repertoire of GPIb-IX-V disorders. Blood 129:403-404
Mao, Guangfen; Songdej, Natthapol; Voora, Deepak et al. (2017) Transcription Factor RUNX1 Regulates Platelet PCTP (Phosphatidylcholine Transfer Protein): Implications for Cardiovascular Events: Differential Effects of RUNX1 Variants. Circulation 136:927-939
Rao, A K; Poncz, M (2017) Defective acid hydrolase secretion in RUNX1 haplodeficiency: Evidence for a global platelet secretory defect. Haemophilia 23:784-792
Michael, James V; Wurtzel, Jeremy G T; Mao, Guang Fen et al. (2017) Platelet microparticles infiltrating solid tumors transfer miRNAs that suppress tumor growth. Blood 130:567-580
Songdej, Natthapol; Rao, A Koneti (2017) Hematopoietic transcription factor mutations: important players in inherited platelet defects. Blood 129:2873-2881
Songdej, Natthapol; Rao, A Koneti (2017) Inherited platelet dysfunction and hematopoietic transcription factor mutations. Platelets 28:20-26
Voora, Deepak; Rao, A Koneti; Jalagadugula, Gauthami S et al. (2016) Systems Pharmacogenomics Finds RUNX1 Is an Aspirin-Responsive Transcription Factor Linked to Cardiovascular Disease and Colon Cancer. EBioMedicine 11:157-164

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