mTOR complex 1 pathway activation in severe keratoconus; the functional implications of GWAS identified loci.

Abstract

PurposeKeratoconus (KC) is an eye condition that can lead to a severe vision loss and may warrant a corneal grafting procedure. Meta-analyses of genome wide association studies have identified several genes that confer risks for differences in corneal curvature, corneal thickness, and developing keratoconus. Currently, there is limited evidence of a functional role for the identified loci in the affected corneal tissues.\n\nMethodsWe investigated the gene expression profiles of 4 GWAS confirmed risk loci and several related pathways that function in cellular ageing and cell cycle control in corneal tissue of a discovery and replication cohort comprising in total 27 keratoconus patients, 16 healthy controls, and 21 diseased controls (failed corneal grafts).\n\nResultsWe confirmed the MTOR gene locus as differentially expressed in KC corneas in a discovery cohort Next, we replicated these results in a second cohort and found evidence of increased expression of various mTORC1 pathway signature genes, namely MTOR itself (P=0.040), AKT1 (P=0.028), IGF1R (P=0.022) and RAPTOR (P=0.007).\n\nConclusionsGene expression profiling in cornea tissues revealed robust up-regulation of the mTORC1 pathway in KC and substantiates a potential role for this pathway in its pathogenesis. Functional implications should be further studied since biomarkers for disease activity are needed and selective targeting of the mTOR pathway is a promising treatment concept.