Defective acid hydrolase secretion in <i><scp>RUNX</scp>1</i> haplodeficiency: Evidence for a global platelet secretory defect

Rao, A Koneti; Poncz, Mortimer

doi:10.1111/hae.13280

Cited by 13 publications

(11 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…14,15 In this study Thrombocytopenia with normal platelet volume occurs in many, but not all, FPD/AML patients, 14,16,31,33 while a varying degree of platelet dysfunction is present in most affected patients. 34,35 Consistent with this, we found RUNX1 L43S/L43S mice to have mild thrombocytopenia, with unaffected platelet size, compared with RUNX1 WT/L43S and RUNX1 WT/WT animals. Our in vitro megakaryopoiesis experiments suggested that the reduced platelet count is related to a slightly delayed MK maturation during the middle stages of megakaryopoiesis in RUNX1 L43S/L43S mice.…”

Section: Discussionsupporting

confidence: 82%

“…38 However, these findings are different from the reduced secretion of the α-and d-granules observed in many FPD/AML patients. 34 Defective fibrinogen/JONA binding and spreading in fibrinogen in mutant mice indicated that the deleterious effect of p.Leu43Ser affects α IIb β 3 integrin insideout and outside-in signaling, respectively. It is worth mentioning that abnormal integrin α IIb β 3 activation has been previously reported in FPD/AML patients.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of the Platelet Phenotype Caused by a Germline RUNX1 Variant in a CRISPR/Cas9-Generated Murine Model

et al. 2021

View full text Add to dashboard Cite

RUNX1-related disorder (RUNX1-RD) is caused by germline variants affecting the RUNX1 gene. This rare, heterogeneous disorder has no specific clinical or laboratory phenotype, making genetic diagnosis necessary. Although international recommendations have been established to classify the pathogenicity of variants, identifying the causative alteration remains a challenge in RUNX1-RD. Murine models may be useful not only for definitively settling the controversy about the pathogenicity of certain RUNX1 variants, but also for elucidating the mechanisms of molecular pathogenesis. Therefore, we developed a knock-in murine model, using the CRISPR/Cas9 system, carrying the RUNX1 p.Leu43Ser variant (mimicking human p.Leu56Ser) to study its pathogenic potential and mechanisms of platelet dysfunction. A total number of 75 mice were generated; 25 per genotype (RUNX1WT/WT, RUNX1WT/L43S, and RUNX1L43S/L43S). Platelet phenotype was assessed by flow cytometry and confocal microscopy. On average, RUNX1L43S/L43S and RUNX1WT/L43S mice had a significantly longer tail-bleeding time than RUNX1WT/WT mice, indicating the variant's involvement in hemostasis. However, only homozygous mice displayed mild thrombocytopenia. RUNX1L43S/L43S and RUNX1WT/L43S displayed impaired agonist-induced spreading and α-granule release, with no differences in δ-granule secretion. Levels of integrin αIIbβ3 activation, fibrinogen binding, and aggregation were significantly lower in platelets from RUNX1L43S/L43S and RUNX1WT/L43S using phorbol 12-myristate 13-acetate (PMA), adenosine diphosphate (ADP), and high thrombin doses. Lower levels of PKC phosphorylation in RUNX1L43S/L43S and RUNX1WT/L43S suggested that the PKC-signaling pathway was impaired. Overall, we demonstrated the deleterious effect of the RUNX1 p.Leu56Ser variant in mice via the impairment of integrin αIIbβ3 activation, aggregation, α-granule secretion, and platelet spreading, mimicking the phenotype associated with RUNX1 variants in the clinical setting.

show abstract

Section: Discussionsupporting

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Characterization of the Platelet Phenotype Caused by a Germline RUNX1 Variant in a CRISPR/Cas9-Generated Murine Model

et al. 2021

View full text Add to dashboard Cite

show abstract

“…While 9% of our index cases (representing 2 families) had probable pathogenic TF mutations affecting RUNX1 , 1 had no family history of leukemia or myelodysplasia. RUNX1 mutations alter gene expression, 19,37‐43 and we found reduced expression of PF4 , MYL9 , and ALOX12 in platelets from PFD participants with RUNX1 haploinsufficiency mutations, with some but not all showing increased MYH10 transcript and protein levels compared to controls. Accordingly, we caution against analyzing MYH10 for diagnostic purposes.…”

Section: Discussionmentioning

confidence: 57%

Bleeding risks for uncharacterized platelet function disorders

Brunet

Badin

Chong

et al. 2020

Research and Practice in Thrombosis and Haemostasis

View full text Add to dashboard Cite

Background The bleeding risks for nonsyndromic platelet function disorders (PFDs) that impair aggregation responses and/or cause dense granule deficiency (DGD) are uncertain. Objectives Our goal was to quantify bleeding risks for a cohort of consecutive cases with uncharacterized PFD. Methods Sequential cases with uncharacterized PFDs that had reduced maximal aggregation (MA) with multiple agonists and/or nonsyndromic DGD were invited to participate along with additional family members to reduce bias. Index cases were further evaluated by exome sequencing, with analysis of RUNX1 ‐dependent genes for cases with RUNX1 sequence variants. Bleeding assessment tools were used to estimate bleeding scores, with bleeding risks estimated as odds ratios (ORs) relative to general population controls. Relationships between symptoms and laboratory findings were also explored. Results Participants with uncharacterized PFD (n = 37; 23 index cases) had impaired aggregation function (70%), nonsyndromic DGD (19%) or both (11%), unlike unaffected relatives. Probable pathogenic RUNX1 variants were found in 2 (9%) index cases/families, whereas others had PFD of unknown cause. Participants with PFD had increased bleeding scores compared to unaffected family members and general population controls, and increased risks for mucocutaneous (OR, 4‐207) and challenge‐related bleeding (OR, 12‐43), and for receiving transfusions for bleeding (OR, 100). Reduced MA with collagen was associated with wound healing problems and bruising, and more severe DGD was associated with surgical bleeding ( P < .04). Conclusions PFDs that impair MA and/or cause nonsyndromic DGD have significantly increased bleeding risks, and some symptoms are more common in those with more severe DGD or impaired collagen aggregation.

show abstract

“…In addition, thrombin induced free arachidonic acid release was unaffected in two patients with a RUNX1 mutation identical to that of the present patient. 31 Thus, the reported effects of inhibiting PCTP on platelet responses 2 are unlikely due to decreased thromboxane production.…”

Section: Discussionmentioning

confidence: 99%

Transcription Factor RUNX1 Regulates Platelet PCTP (Phosphatidylcholine Transfer Protein): Implications for Cardiovascular Events

et al. 2017

View full text Add to dashboard Cite

Background Phosphatidylcholine Transfer Protein (PCTP) regulates the intermembrane transfer of phosphatidylcholine (PC). Higher platelet PCTP expression is associated with increased platelet responses upon activation of protease-activated receptor 4 (PAR4) thrombin receptors noted in black subjects as compared to white subjects. Little is known regarding regulation of platelet PCTP. Haplodeficiency of RUNX1, a major hematopoietic transcription factor, is associated with thrombocytopenia and impaired platelet responses upon activation. Platelet expression profiling of a patient described by us with a RUNX1 loss-of-function mutation revealed a 10-fold downregulation of PCTP gene compared with healthy controls. Methods We pursued the hypothesis that PCTP is regulated by RUNX1 and that PCTP expression is correlated with cardiovascular events. We studied RUNX1 binding to PCTP promoter using DNA-protein binding studies and human erythroleukemia (HEL) cells, and promoter activity using luciferase reporter studies. We assessed the relationship between RUNX1 and PCTP in peripheral blood RNA and PCTP and death or myocardial infarction (MI) in two separate patient cohorts (587 total patients) with cardiovascular disease. Results Platelet PCTP protein in the patient was reduced by ~50%. DNA-protein binding studies showed RUNX1 binding to consensus sites in ~1 kB of PCTP promoter. PCTP expression was increased with RUNX1 overexpression and reduced with RUNX1 knockdown in HEL cells, indicating that PCTP is regulated by RUNX1. Studies in two cohorts of patients showed that RUNX1 expression in blood correlated with PCTP gene expression; PCTP expression was higher in black compared to white subjects, and associated with future death/myocardial infarction after adjusting for age, sex, and race (odds ratio 2.05, 95% CI [1.6–2.7], P-value < 0.0001). RUNX1 expression is known to initiate at two alternate promoters, a distal P1 and a proximal P2 promoter. In patient cohorts there were differential effects of RUNX1 isoforms on PCTP expression with a negative correlation in blood between RUNX1 expressed from the P1 promoter and PCTP expression. Conclusions PCTP is a direct transcriptional target of RUNX1. PCTP expression is associated with death/myocardial infarction in patients with cardiovascular disease. RUNX1 regulation of PCTP may play a role in the pathogenesis of platelet-mediated cardiovascular events.

show abstract

Defective acid hydrolase secretion in RUNX1 haplodeficiency: Evidence for a global platelet secretory defect

Cited by 13 publications

References 29 publications

Characterization of the Platelet Phenotype Caused by a Germline RUNX1 Variant in a CRISPR/Cas9-Generated Murine Model

Characterization of the Platelet Phenotype Caused by a Germline RUNX1 Variant in a CRISPR/Cas9-Generated Murine Model

Bleeding risks for uncharacterized platelet function disorders

Transcription Factor RUNX1 Regulates Platelet PCTP (Phosphatidylcholine Transfer Protein): Implications for Cardiovascular Events

Contact Info

Product

Resources

About