Galectin-1 regulates expression and alternative splicing of angiogenic genes by interacting with their RNAs in HUVECs

Background: Angiogenesis is an essential step for tissue development and its dysregulation is associated with various diseases, including moyamoya disease. Among the regulators of angiogenesis, galectin-1 encoded by LGALS1, plays essential roles, but the underlying mechanisms need to be further expounded. In this study, we systematically investigated the potential targets of galectin-1 by silencing LGALS1 (siLGALS1) in human umbilical vein endothelial cells (HUVECs) and performing whole transcriptome sequencing (RNA-seq) experiments. We also integrated galectin-1-interacting RNA data to explore how galectin-1 regulates gene expression and alternative splicing. Results: By systematical analysis, we found siLGALS1 treatment significantly regulated 1451 differentially expressed genes (DEGs), including 604 up-regulated DEGs and 847 down-regulated DEGs. The down-regulated DEGs were significantly enriched in angiogenesis and inflammatory response pathways. The involved genes included CCL2, GJA5, CALCRL, ACKR3, HEY1, AQP1, CD34, ECM1, RAMP2, and SELP, which were also validated by RT-qPCR experiment. We also analyzed the dysregulated alternative splicing (AS) profile by siLGALS1, and found siLGALS1 had obvious bias for dysregulated AS types, preferring to promote exon skipping and intron retention, and inhibit cassette exon events. Interestingly, we found the regulated AS genes (RASGs) were enriched in focal adhesion and VEGF signaling pathway, which were highly related to angiogenesis. Finally, we found hundreds of RASGs were also bound by galectin-1 using the published iRIP-seq data of galectin-1, including RASGs from angiogenesis pathway. Conclusions: In summary, our results demonstrated that galectin-1 could regulate angiogenesis-related genes at transcriptional and post-transcriptional levels, which is associated its RNA binding ability in HUVECs. The discovery extends our understanding on the functions and molecular mechanisms of galectin-1 during the development of angiogenesis, which could be served as a therapeutic option in anti-angiogenic treatment in future. We silenced LGALS1 expression in human umbilical vein endothelial cells (HUVECs) in this study, and then performed whole transcriptome sequencing experiment (RNA-seq) to extensively explore the regulated expression and alternative splicing levels.