Study On Synergistic Effect And Mechanisms Of Galectin-1 And MGL-mediated Jurkat Cell Apoptosis

It is one of important mechanisms for tumor escape, which induces T cell apoptosis and reduces the body cell immunity. Previous studies have found that galectin-1(Gal-1) can induce T cell apoptosis that is secreted by malignant cell. Moreover, macrophage galactose-type lectin(MGL) can also induce T cell apoptosis, which expressed on immature dentritic cells(i DC) and tolerogenic dentritic cell(t DC). However, it is unknown which signal pathway primes T cell apoptosis and whether MGL cooperated with Gal-1 induces T cell apoptosis.In this study, firstly, we purified Gal-1 protein of inducible expression in vitro, followed by construction of the prokaryotic expression vector of Gal-1. Secondly, we investigated signal pathways of Gal-1 and MGL-mediated T cell apoptosis, respectively. Finally, we detected that whether MGL cooperated with Gal-1 induce T cell apoptosis. In the whole study, Jurkat cell line was used as T cell model in vitro.In order to get enough Gal-1 protein applied to our experiment, we conducted the construction of the prokaryotic expression vector of Gal-1. We got it successfully shown by PCR, restriction enzyme digestion and nucleotide sequencing. After optimizing prokaryotic expression conditions, we got soluble Gal-1 protein that could bind to Jurkat cells. In the assay of Gal-1-mediated T cell apoptosis, we firstly verified that Gal-1 could be secreted by four kinds of leukemia cell line, including THP-1, U937, KG1 and K562. Secondly, Gal-1 could induce T cell apoptosis determined by FACS after incubation with T cell. Then we found that Gal-1 induced caspase-independent and AIF-independent T cell apoptosis determined by Western blot and immunofluorescence. In the assay of MGL-mediated T cell apoptosis, we firstly verified that MGL was expressed specifically by i DC. Secondly, MGL could also induce T cell apoptosis determined by FACS after incubation with T cell. MGL induced nuclear translocation of AIF in caspase-independent T cell apoptosis determined by Western blot and immunofluorescence. The above results have indicated that Gal-1 and MGL induce T cell apoptosis by different signal pathways, we therefore speculated that Gal-1 may cooperated with MGL induce T cell apoptosis. FACS results then confirmed our speculation following incubation of Gal-1 and MGL together with Jurkat cells.Our study on the synergistic effect and mechanisms of Gal-1 and MGL-mediated T cell apoptosis, which is helpful to reveal the molecular mechanism of immune escape of malignant leukemia cell, but also provide experimental foundation for development of candidates, which can block leukemia cell inducing T cell apoptosis.