Aniridia is a rare genetic disorder that affects the development of the eye and is caused in most cases by mutations in the PAX6 gene. Patients with a heterozygous mutation in their PAX6 gene are born without irises. Aniridia patients are also prone to other eye diseases over their lifetimes such as cataracts and glaucoma. Aniridia’s progressive nature suggests that therapeutic intervention aimed at restoring PAX6 expression may be effective at ameliorating the progression of this disease. PAX6 is necessary for the development and maintenance not only of the eye, but also the pancreas. Patients with aniridia have an increased likelihood of developing glucose intolerance and diabetes. Indeed, genetic studies in rodents have confirmed that haploinsufficient animals for Pax6 develop glucose intolerance due to an ongoing requirement for Pax6 expression in the pancreas and gut. This thesis is a proof-of-concept study designed to determine the effects of repressing miRNA regulation of murine Pax6. Pax6 is regulated by miRNA-7 and miRNA-375. I hypothesized that repression of miRNA-7 and miRNA-375 would restore Pax6 expression and that this strategy might be useful in treating some of the progressive symptoms that emerge in aniridia patients in adulthood. As a first step towards evaluating miRNA inhibition as a therapeutic strategy for the treatment of aniridia, my first objective was to confirm whether miRNA-7 and miRNA-375 regulate Pax6 expression in pancreatic cells and tissue. My second objective was to determine whether these miRNAs could be efficiently inhibited. My third objective was to determine whether repression of miRNA-7 or miRNA-375 alters endogenous PAX6 protein levels in pancreatic cell lines. My final objective was to determine whether target protectors, delivered to explants of pancreatic islets through an adeno-associated virus (AAV) vector, could be used to restore Pax6 expression in murine haploinsufficient islets. From this study, I have confirmed that miRNA-7 and miRNA-375 regulate Pax6 in pancreatic cells that these miRNAs can be specifically inhibited, and that inhibition leads to an increase in Pax6 on both the reporter and protein levels. I have shown that target protectors against the miRNA-7 and miRNA-375 binding sites within the Pax6 3’UTR are effective at increasing the levels of PAX6 protein in pancreatic cell lines. Finally, I have also shown that a target protector against the miRNA-7 binding site can increase PAX6 protein levels in islets from murine haploinsufficient islets to near wild-type levels. My thesis lays the groundwork for the development of anti-miRNA-based therapies aimed at restoring PAX6 expression in the eye and pancreas. / Graduate