SUMOylation of GMFB regulates the stability and function of GMF in RPE cells under oxidative stress and inflammation

Glia maturation factor beta (GMFB) is a growth and differentiation factor that act as an intracellular regulator of signal transduction pathways. The SUMOylation is a post-translational modification (PTM) that plays a key role in protein subcellular localization, stability, transcription, and enzymatic activity. Recent studies have highlighted the importance of SUMOylation in the inflammation and progression of numerous diseases. But little is known about the relationship between GMFB and SUMOylation. Here we first report that GMFB can be mono-SUMOylated at multiple sites by the covalent addition of a single SUMO1 protein, and identified K20, K35, K58, and K97 as major SUMO acceptor sites. We also found that SUMOylation leading to increased stability and trans-localization of GMFB. Furthermore, RNA-seq data and Real-time quantitative polymerase chain reaction (rt-qPCR) also indicated that the SUMOylated GMFB upregulated multiple pathways, including the cytokine-cytokin receptor interaction, NOD-like receptor signaling pathway, TNF signaling pathway, RIG-I-like receptor signaling pathway, and NF-kappa B signaling pathway. Our studies intend to provide a novel direction for the study into the biofunction of GMFB, SUMOylated GMFB and the mechanism, clinical therapy, and prognosis of inflammation-related RPE disorders like age-related macular degeneration (AMD) and diabetic retinopathy (DR).