Analysis of association between MALAT1 haplotype and the severity of Normal Tension Glaucoma (NTG)

Abstract Background: The haplotype in MALAT1 affects its expression and is correlated with human diseases like Normal Tension Glaucoma (NTG), although its detailed mechanism remains unclear. Methods: Quantitative real-time PCR was performed to assess the expression of MALAT1, miR-1 and IL-6 in the serum of NTG patients with different haplotypes of MALAT1, as well as in HUVEC and HTMC cells transfected with MALAT1. ELISA was used to analyze the IL-6 level in the serum of NTG patients. RNFL thickness, RA and C/D ratio were calculated for NTG patients. A luciferase assays was carried out to evaluate the inhibitory effect of miR-1 on MALAT1 and IL-6 expression. Western blot was used to analyze the IL-6 protein level in HUVEC and HTMC cells transfected with MALAT1.Results: Accordingly, GGGT haplotype was demonstrated to be associated with a decreased risk of NTG. The MALAT1 level in serum of NTG patients carrying GGGT haplotype was significantly decreased compared with NTG patients carrying other haplotypes, along with elevated miR-1 expression and diminished IL-6 expression. NTG patients carrying GGGT haplotype had thicker RNFL and RA, but a smaller C/D ratio. Sequence analysis found potential target sites of miR-1 on MALAT1 and IL-6, and luciferase assay confirmed the inhibitory effect of miR-1 on MALAT1 and IL-6 expression. Meanwhile, MALAT1 also down-regulated miR-1 expression and consequently up-regulated IL-6 expression. Conclusion: This study presented evidence for a regulatory network containing MALAT1, miR-1 and IL-6, and further demonstrated the effect of MALAT1 haplotype on the risk and severity of NTG.