The duplication mutation of Quebec platelet disorder dysregulates PLAU, but not C10orf55, selectively increasing production of normal PLAU transcripts by megakaryocytes but not granulocytes

Abstract

Quebec Platelet disorder (QPD) is a unique bleeding disorder that markedly increases urokinase plasminogen activator (uPA) in megakaryocytes and platelets but not in plasma or urine. The cause is tandem duplication of a 78 kb region of chromosome 10 containing PLAU (the uPA gene) and C10orf55, a gene of unknown function. QPD increases uPA in platelets and megakaryocytes >100 fold, far more than expected for a gene duplication. To investigate the tissue-specific effect that PLAU duplication has on gene expression and transcript structure in QPD, we tested if QPD leads to: 1) overexpression of normal or unique PLAU transcripts; 2) increased uPA in leukocytes; 3) altered levels of C10orf55 mRNA and/or protein in megakaryocytes and leukocytes; and 4) global changes in megakaryocyte gene expression. Primary cells and cultured megakaryocytes from donors were prepared for quantitative reverse polymerase chain reaction analyses, RNA-seq and protein expression analyses. Rapidly isolated blood leukocytes from QPD subjects showed only a 3.9 fold increase in PLAU transcript levels, in keeping with the normal to minimally increased uPA in affinity purified, QPD leukocytes. All subjects had more uPA in granulocytes than monocytes and minimal uPA in lymphocytes. QPD leukocytes expressed PLAU alleles in proportions consistent with an extra copy of PLAU on the disease chromosome, unlike QPD megakaryocytes. QPD PLAU transcripts were consistent with reference gene models, with a much higher proportion of reads originating from the disease chromosome in megakaryocytes than granulocytes. QPD and control megakaryocytes contained minimal reads for C10orf55, and C10orf55 protein was not increased in QPD megakaryocytes or platelets. Finally, our QPD megakaryocyte transcriptome analysis revealed a global down regulation of the interferon type 1 pathway. We suggest that the low endogenous levels of uPA in blood are actively regulated, and that the regulatory mechanisms are disrupted in QPD in a megakaryocyte-specific manner.

Application of weighted gene co-expression network analysis to identify key modules and hub genes in oral squamous cell carcinoma tumorigenesis

“…However, in Quebec platelet disorder, tandem duplication of a 78 kb region of chromosome 10 containing PLAU (the uPA gene) would lead to increasing production of normal PLAU transcripts. 43 FSCN1 encodes for a member of the fascin family of actin-binding proteins, which plays a critical role in cell migration, motility, adhesion and cellular interactions. It has been reported that overexpression of this gene may play a role in the metastasis of multiple types of cancer by increasing cell motility.…”

A Comprehensive Overview of Coagulation Factor V and Congenital Factor V Deficiency

“…28,38 The definitive diagnosis of QBD is molecular screening for tandem duplication of a-78 kb region of chromosome 10 containing PLAU and C10orf55, a gene without a determined function. 39 QBD causes bleeding problems within 12 hours to 4 days unless it is treated with antifibrinolytic agents including tranexamic acid or aminocaproic acid. Other treatments including plasma and platelet transfusion are not useful in patients with QBD.…”

Genetic Techniques Used in the Diagnosis of Inherited Platelet Disorders

“…The capacity of WGS to detect noncoding variants enables detection of causal variants underlying most forms of thrombocytopenia absent radius syndrome (RBM8A) and Quebec platelet disorder (PLAU), 45,46 which are associated with variants in regulatory regions outside coding exons. Noncoding regulatory regions are also good candidate regions for causal variants in 40% of Mendelian IPD which cannot currently be assigned to specific genes.…”