FRG1 is a direct transcriptional regulator of nonsense-mediated mRNA decay genes

Abstract

FRG1 is the primary candidate gene for Fascioscapulohumeral Muscular Dystrophy. So far, its role has been reported in muscle development, vasculogenesis, angiogenesis, and tumorigenesis. Mechanistically studies suggest FRG1's role in RNA biogenesis which may have implications in multiple physiological processes and diseases, including tumorigenesis. Its probable role as hnRNP and association with NMD-related genes prompted us to look into FRG1's effect on NMD gene expression and the mechanism. Using microarray profiling in cell lines, we found that FRG1 altered the mRNA surveillance pathway and associated pathways, such as RNA transport and spliceosome machinery molecules. Multiple sequence alignment of core factors, namely, UPF1, UPF3B, and SMG1, showed conserved stretches of nucleotide sequence ‘CTGGG’. Structural modeling followed by EMSA, ChIP-qPCR, and luciferase reporter assays showed ‘CTGGG’ as a FRG1 binding site. Analysis of the publicly available datasets showed that the expression of FRG1 correlates with NMD genes in different tissue types. We validated the effect of FRG1 on NMD gene transcription by qRT-PCR. Overall, FRG1 might be a transcriptional regulator of NMD genes.