Galectin-1-RNA interaction map reveals its novel regulatory roles in angiogenesis

Hyperactive angiogenesis contributes to the immunosuppressive microenvironment important for immunotherapy, and LGALS1-encoed galectin-1 can trigger vascular signaling programs and mediate anti-angiogenic treatment response. However, the mechanism of galectin-1 regulation of angiogenesis is poorly understood. Previous mRNA interactome studies suggested that galectin-1 associated with mRNAs. In this study, we applied the iRIP-seq methodology, an unbiased genome-wide approach to study the RNA binding profiles of galectin-1. The results demonstrate that galectin-1 interacted with a large population of mRNAs with a preferred location towards stop codon, and preferred motifs of UGCA/UGGA and GAGCAG motifs. Galectin-1-bound mRNAs are enriched in cell cycle control and diverse basic biological processes, including its previously reported protein targets H-Ras and also T cell receptors TLR6. Glectin-1 significantly binds to genes in angiogenesis, which included the key pro-angiogenic growth factor VEGFA, angiogenic regulators EGR1 and LAMA5, suggesting that galectin-1 may regulate via its mRNA binding activity. The presented results uncover an previously unrecognized mRNA binding activity of galectin-1; further pursue of this activity could lead to knowledge important for developing therapeutic strategies against cancer and other diseases involved in aberrant angiogenesis. Overall design: RIP-seq analysis of LGALS1 IP versus input in Hela cells