In a recent paper, Horita H. et al. identified a set of novel Post-Translational Modifications (PTMs) of the protein Programmed Cell Death Ligand (PD-L1).
For this, a novel series of PTM enrichment assays enabling the highly specific profiling of 4 key PTM profiles (Tyrosine phosphorylation (pY), Acetylation (Ac), Unbiquitination (Ub) and SUMOylation 2/3), have been used on EGF-stimulated A431 cell line. They revealed that EGF induced pY, Ac, mono- and poly-Ub Of PD-L1 in these EGF treated epidermoid carcinoma cells. The authors also suggested that the balance between mono- / poly-Ub of PD-L1 might regulate PD-L1 stability, as already described with LDB-1 protein.
These novel PD-L1 PTMs and their related regulatory actions might be valuable information in the future for the design of drug strategies targeting PD-L1/PD-1 immune checkpoint inhibition.