Identification of microRNAs targeting PROX1 and their role in mediating Dilated Cardiomyopathy
Dilated cardiomyopathy (DCM) is one the most common heart conditions in the world and the leading cause of heart failure (HF). However, the link between the DCM disease genotypes and disease progression into is not evident. To address this gap, my thesis research explored the control of DCM disease manifestations by miRNAs regulation of their mRNA targets. I used PROX1 as a seed to link mechanical stress and DCM phenotypes. I developed a high throughput functional screen of synthetic miRNA mimics for the suppression of PROX1 mRNA that revealed 18 miRNAs that inhibit PROX1 by binding to the 3’ untranslated region (3’ UTR). Among their computationally predicted protein targets, we identified those that belong to known pathways that are relevant to DCM phenotypes. Furthermore, we identified four miRNAs that target PROX1 and were dysregulated in cardiomyocytes under mechanical stress. Pursing these miRNAs in more depth, I generated hypothetical signaling modules connecting mechanical stress to miRNAs and proteins involved in the DCM phenotypes. Confirmation of their actual involvement awaits direct experimental verification of biochemical interaction with the miRNAs, and functional demonstration that they play a role in DCM pathogenesis using in vitro cardiomyocyte physiology and animal models. Nonetheless, there are three main conclusions to my thesis research: (1) It is possible to use a single dysregulated protein (PROX1) as a seed to construct a miRNA-protein network using a combination of experimental and computational studies, (2) several miRNAs are identified to selectively downregulated PROX1 and are predicted to coordinately regulated PROX1, and (3) these miRNAs that downregulate PROX1 also downregulates proteins that are involved in other DCM phenotypes.