Abstract Number: OC 31.1
Meeting: ISTH 2021 Congress
Theme: Platelet Disorders, von Willebrand Disease and Thrombotic Microangiopathies » Platelet Function Disorders, Hereditary
Background: Plasma factor XIII, consisting of two A (FXIII-A, gene F13A1) chains with transglutaminase activity and two B (FXIII-B), cross-links fibrin and regulates clot retraction (CR). FXIII-A is synthesized in megakaryocytes (MK) and abundant in platelets. Little is known regarding its regulation in MK. RUNX1 regulates gene expression in MK/platelets. RUNX1 haplodeficient (RHD) patients with heterozygous mutations have platelet defects.
Aims: To study mechanisms leading to decreased platelet F13A1 expression in RHD.
Methods: We studied regulation of F13A1 by RUNX1 in PMA-treated megakaryocytic HEL cells and CR in platelets and HEL cells.
Results: Platelet expression profiling (microarray) of patient (P1) with RUNX1 mutation (c.352-1 G>T) revealed decreased F13A1 expression (fold change 0.30; p=0.006; compared to 6 normals). By qPCR, platelet F13A1 mRNA expression was decreased with FXIII-A protein ~50%. Plasma FXIII-A (ELISA) was near normal. Platelet F13A1 mRNA was decreased in two siblings (ages 8 and 3 years) from an unrelated family with RUNX1 mutation (c.508+1 G>A). F13A1 promoter studies in HEL cells indicated that RUNX1 regulates F13A1: CHIP and EMSA showed RUNX1 binding to promoter region. RUNX1 overexpression increased F13A1 promoter activity and protein, and siRNA RUNX1 knockdown reduced FXIII-A protein. CR over 90 min studied in patient P1 and affected daughter in washed platelets suspended in plasma and clotted with thrombin was decreased. With HEL cells suspended in plasma or buffer (added fibrinogen), CR following thrombin clotting was decreased on siRNA downregulation of RUNX1 or F13A1, as was HEL cell FXIII-A surface expression on activation (convulxin+thrombin) by flow cytometry.
Conclusions: This is first evidence that RUNX1 regulates F13A1 expression in megakaryocytic cells and that platelet F13A1 expression is decreased in RHD, reflecting regulation of a coagulation protein by a hematopoietic transcription factor. Clot retraction is impaired in RHD platelets and RUNX1 deficient HEL cells, due to altered expression of multiple RUNX1 regulated genes.
To cite this abstract in AMA style:
Del Carpio-Cano F, Songdej N, Mao G, Wurtzel J, Goldfinger L, Lambert MP, Rao A. Transcription Factor RUNX1 Regulates Factor XIIIA Subunit (F13A1) Expression in Platelets and Megakaryocytic Cells: Decreased Platelet F13A1 Expression and Clot Retraction in RUNX1 Haplodeficiency [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/transcription-factor-runx1-regulates-factor-xiiia-subunit-f13a1-expression-in-platelets-and-megakaryocytic-cells-decreased-platelet-f13a1-expression-and-clot-retraction-in-runx1-haplodeficiency/. Accessed August 9, 2022.« Back to ISTH 2021 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/transcription-factor-runx1-regulates-factor-xiiia-subunit-f13a1-expression-in-platelets-and-megakaryocytic-cells-decreased-platelet-f13a1-expression-and-clot-retraction-in-runx1-haplodeficiency/