The signal transduction pathway of insulin promoting stem cell factor expression in colonic smooth muscle cells / 中华消化杂志

ABSTRACT

Objective To investigate the intracellular signal transduction pathway of insulin promoting stem cell factor (SCF) expression in colonic smooth muscle cells (SMCs).Methods Colonic SMCs from SD rats were isolated and cultured, which were identified by α-actin immunofluorescence cytochemistry staining.SMCs were divided into 3 groups for experiment. ①Insulin concentration gradient groupAdding different insulin concentrations (0,2.5,5,20,40 and 80 mg/L) into SMCs culture and cultured for 16 hours; ② Insulin time point groupSMCs were cultured with insulin (40 mg/L) for different time durations (0,8,16,24 hours); ③ Signal pathway blocking groupSMCs were pretreated with LY-294002 or PD-98059,and then induced with insulin (40 mg/L) for 16 h.The proliferation of SMCs was examined by MTT method.The change of SCF expression was determined by Western blot and RT-PCR.Results ① Insulin at concentration of 5 mg/L remarkably promoted SMCs proliferation,and there was no significant difference in its effect with insulin concentrations at 20,40,80 mg/L (all P＜0.05).② Compared with no insulin adding group,low and medium dose of insulin (2.5,5,20 mg/L) already had a role in promoting SCF mRNA and SCF protein expression (all P ＜ 0.05). It reached maxium effect when insulin concentration was at 40 mg/L(P＜0.05),and there was no significant difference between insulin concentration at 40 mg/L and 80 mg/L (P＞0.05).③ Compared with time 0 hour,the expression of SCF increased after insulin worked on SMC (40 mg/L) for 8 hours (P＜0.05),and reached the peak after 16 hours (P＜0.05),and there was no significant difference between 24 hours and 16 hours (P＞0.05).④ Compared with blank control group and solvent control group,both insulin-induced SCF expression reduced after pretreated with LY-294002 or PD-98059 (all P＜0.05).Conclusions Insulin can promote SMCs proliferation,and in certain range the induction of SCF synthesis in colon SMCs is in dose and time dependent manners.The effect may be related to PI3K and MAPK signal pathway.