IGF2 Regulates Neuronal Differentiation of Hippocampal Radial Glial Cells In Vitro

Abstract

We previously observed that radial glial(RG)-like cells showed larger soma, thicker and longer neuritis in vivo(i.e., in rats) after fimbria-fornix (FF) transection, and in vitro RG-like cells showed the same results after the application of the extract from FF-transected hippocampus. In the present study, RG-like cells cultured in 24-well plates supplemented with 5% extract from FF-transected hippocampus were more likely to differentiate into neurons, compared with a normal group. After receiving the insulin-like growth factor 2 (IGF2) gene and knockdown or over expression viruses, the influence of IGF2 on the differentiation of RG-like cells into neurons and the expression of IGF2 were measured. Then, real-time polymerase chain reaction (real-time PCR), enzyme-linked immunosorbent assay (ELISA), and immunofluorescence were used to detect the differentiation of the RG-like cells into neurons. ELISA and real-time PCR showed that the expression of IGF2 in the IGF2 over expression (IGF2 OE) group was significantly higher compared to the normal group. However, the expression of IGF2 in the FF+IGF2 knockdown (FF+IGF2 KD) group was significantly lower than in the FF group. Moreover, the number of MAP2-positive neurons produced in the FF+IGF2 KD group, which expressed less IGF2, was significantly lower compared with the FF group, but the number of MAP2-positive neurons was significantly higher in the IGF2 OE group. The differentiation of RG-like cells into neurons was correlated with a significant increase in the expression of IGF2, indicating that IGF2 was an important regulatory factor for the extract to stimulate the differentiation of RG-like cells into neurons.