Knocking-down Synaptotagmin 1 Attenuated Colitis via Suppressing the IL-6/STAT3 Signaling Pathway / 中国生物化学与分子生物学报

ABSTRACT

Synaptotagmin 1 (Sytl) is a member of the Synaptotagmin family and plays a role in neurotransmitter vesicle transport and exoeytosis. It has been reported that Sytl appears to be expressed in the intestinal epithelium, but the biological function of Sytl in colitis remains poorly understood. This study aimed to investigate the effects of Sytl in the inflammatory response and intestinal epithelial regeneration in colitis using Sytl transgenic mice and dextran sulfate sodium (DSS)-induced ulcerative colitis mode. qRT-PCR and Western blotting were employed to analyze the dynamic changes of Sytl in colitis. H&E staining, immunostaining and Western blotting were used to explore the roles of Sytl in the inflammatory response and in the regeneration and repair of intestinal epithelium in colitis. The results showed that the expression level of Sytl was indeed high in the colonic epithelium of wild-type mice and the intestinal epithelial cells of the adjacent tissues of colorectal cancer patients. Consistently, DSS-induced inflammation progressively resulted in marked upregulation of Sytl in the colon (P<0.01). In DSS-induced colitis, both the body weight loss and colonic shortening were dampened in Sytl loss-of-function mice compared with the control group (P < 0.05), while the number of regenerated crypts and Ki67 proliferating cells were also increased (P<0.01). Additionally, there were less infiltration of CD45 immune cells and F 4/80 macrophages and the expression of pro-inflammatory cytokines IL-6, TNFα and I L l-β, which were related with the severity of inflammation in the inflammatory bowel disease (I B D), were significantly decreased after Sytl deletion (P<0.05). Immunohistochemistry staining and Western blotting results further showed that IL-6 and p-STAT3 was significantly downregulated in Sytl knockdown mice (P<0.05). Taken together, these results suggested that knocking-down of Sytl may improve colitis by inhibiting the IL6/STAT3 signaling pathway.