N端结构域在Galectin-3诱导T细胞凋亡中的作用

Galectin-3 (Gal-3), a β-galactoside-binding protein, consists of an N-terminal leading domain (LD) followed by a collagen-like repeating domain (RD) that is connected to a carbohydrate recognition domain (CRD) at the C-terminus. Gal-3 can induce T-cell apoptosis and is associated with tumor escape from immune surveillance. The relationship between Gal-3 structure and its apoptotic activity remains elucidative. Here we investigated the functions of each structural domain by comparative analysis of the full length protein with various truncated proteins (G13-250、G69-250、G111-250 and G1-108) using the approaches of FITC-AnnexinV/PI double staining, western blot (for activated caspase-3) and flow cytometry (for the Sub G1 cell population). The results showed that the CRD is prerequisite for Gal-3's pro-apoptotic action. However, the CRD alone is unable to induce apoptosis and it must connect to a segment of the N-terminal tail for function. While the LD is not required, the RD plays a pivotal role in initiating apoptosis. Further studies with inhibitors specific to the N-terminal tail and CRD confirmed these results. This study reveals the functions of the LD and RD in Gal-3 induced T-cell apoptosis and is useful for the development of galectin-3-targeting anti-cancer therapeutics.