Glaucoma is the leading cause of blindness worldwide. It is a genetic disease, but usually not monogenic. In an earlier study, PITX2 (pituitary homeobox2) target genes were identified. PITX2 is a transcription factor which affects the development of the eye, and mutations in its encoding gene are a common cause of Axenfeld-Rieger syndrome (ARS). As ARS is very often accompanied with glaucoma, it is reasonable to consider that its malfunction or the malfunction of its target genes may contribute to glaucoma. NOMO2 that encodes NODAL modulator 2 was among the PITX2 target genes. NODAL signaling is a form of TGFB signaling, and TGFB signaling is an important glaucoma related pathway. In addition to transcription factors, microRNAs are important components in the regulation of most normal and abnormal biological processe. Given this background, we aimed to identify miRNAs that may affect the expression of PITX2, NODAL, and NOMO2.

In silico searches in publically available web sites including MiRwalk were performed in order to identify miRNAs that are expressed in the trabecular meshwork and that may target PITX2, NODAL, or NOMO2. The trabecular meshwork is a glaucoma relevant tissue because it affects intraocular pressure. Four miRNAS were selected and their effects on the genes were assessed using a luciferase dual assay. The luciferase assay was performed in HEK293 cells transfected with the miRNAs and with vectors in which the 3'UTR segments of the genes were cloned downstream of coding sequences of a luciferase encoding gene.

In silico searches predicted that miR-193b and miR-17 may target NOMO2, miR-146 and miR-193b may target NODAL, and miR-204 may target PITX2. The luciferase assays did not confirm the predicted effects of miR-193b and miR-17 on NOMO2. However, as predicted by the bioinformatics tools, miR-146 and miR-193b did target the NODAL 3'UTR, and miR-204 did target the PITX2 3'UTR.

Results of earlier experiments suggested that PITX2, NODAL, and NOMO2 functions may have relevance to glaucoma. Here, we showed that miR-146, miR-193b, and miR-204 target NODAL or PITX2 and may, therefore, also have roles in the etiologies of the disease.