Large-scale identification of functional microRNA targeting reveals cooperative regulation of the hemostatic system.

Background: microRNAs (miRNAs) confer robustness to complex molecular networks regulating biological functions. However, despite the involvement of miRNAs in almost all biological processes, and the importance of the hemostatic system for a multitude of actions in and beyond blood coagulation, the role of miRNAs in hemostasis is poorly defined. Objectives: Here we comprehensively illuminate miRNA-mediated regulation of the hemostatic system in an unbiased manner. Methods: In contrast to widely applied association studies, we used an integrative screening approach that combines functional aspects of miRNA silencing with biophysical miRNA interaction based on RNA pull-downs (miTRAP) coupled to next-generation sequencing. Results: Examination of a panel of 27 hemostasis-associated gene 3'UTRs revealed the majority to possess substantial Dicer-dependent silencing capability, suggesting functional miRNA targeting. miTRAP revealed 150 specific miRNA interactions with 14 3'UTRs, of which 52, involving 40 miRNAs, were functionally confirmed. This includes cooperative miRNA regulation of key hemostatic genes comprising procoagulant (F7, F8, F11, FGA, FGG and KLKB1) and anticoagulant (SERPINA10, PROZ, SERPIND1 and SERPINC1) as well as fibrinolytic (PLG) components. Bioinformatic analysis of miRNA functionality reveals established and potential novel links between the hemostatic system and other pathologies, such as cancer, bone metabolism and renal function. Conclusions: Our findings provide, along with an in-vivo proof of concept, deep insights into the network of miRNAs regulating the hemostatic system and present a foundation for biomarker discovery and novel targeted therapeutics for correction of de-regulated hemostasis and associated processes in the future. A repository of the miRNA targetome covering 14 hemostatic components is provided.