Abstract
Tissue factor pathway inhibitor (TFPI) is an anticoagulant protein that inhibits factor VIIa and Xa in the coagulation cascade. It has been shown that forkhead box P3 protein is a TFPI transcriptional repressor. However, there are no studies on chromatin remodeling that control TFPI expression. We hypothesized that the genome-wide knockdowns of the chromatin binding and regulatory proteins (CBRPs) in zebrafish could identify novel tfpia gene regulators. As an initial step, we selected 69 CBRP genes from the list of zebrafish thrombocyte-expressed genes. We then performed a 3-gene piggyback knockdown screen of these 69 genes, followed by quantification of tfpia mRNA levels. The results revealed that knockdown of brd7, ing2, ing3, ing4, and suz12b increased tfpia mRNA levels. The simultaneous knockdown of these 5 genes also increased tfpia mRNA levels. We also performed individual gene and simultaneous 5-gene knockdowns on the 5 genes in zebrafish larvae. We found that after laser injury, it took a longer time for the formation of the thrombus to occlude the caudal vessel compared to the control larvae. We then treated the larvae and adults with a chemical UNC6852 known to proteolytically degrade polycomb repressor complex 2, where SUZ12 is a member, and observed prolongation of time to occlude (TTO) the caudal vein after laser injury and increased tfpia mRNA levels in larvae and adults, respectively. In summary, our results have identified novel epigenetic regulators for tfpia and exploited this information to discover a drug that enhances tfpia mRNA levels and prolongation of TTO. This discovery provides the basis for testing whether UNC6852 could be used as an antithrombotic drug. This approach could be used to study the regulation of other plasma proteins, including coagulant and anticoagulant factors.
Highlights
Tissue factor pathway inhibitor (TFPI) is an anticoagulant that inhibits blood coagulation pathway enzymes VIIa and Xa
Since TFPI is expressed in megakaryocytes and thrombocytes have similar transcription factors expressed in megakaryocytes, we first examined single-cell RNAseq data from our laboratory for the transcripts expressed in zebrafish thrombocytes and found transcripts for 69 chromatin binding and regulatory proteins (CBRPs) as well as tfpia transcripts
To identify whether any of the 69 CBRPs are involved in tfpia gene expression, as an initial step, we selected all 69 CBRP mRNAs, and they were divided into 23 sets for a 3-gene knockdown
Summary
Tissue factor pathway inhibitor (TFPI) is an anticoagulant that inhibits blood coagulation pathway enzymes VIIa and Xa. We selected 69 CBRP genes from the single-cell RNAseq analysis of zebrafish thrombocyte transcripts identified in our laboratory, performed a knockdown screen of these genes in adult zebrafish, and measured tfpia mRNA levels by qRT-PCR. This screen revealed knockdown of brd[7], ing[2], ing[3], ing[4], and suz12b genes individually, increased tfpia mRNA levels. Our results showed knockdown of brd[7], ing[2], ing[3], ing[4], and suz12b increased tfpia mRNA levels, and SUZ12 inhibitor gave an antithrombotic phenotype This epigenetic approach could be used to control coagulation factors
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