[Effect of erythroid enhancer on the expression of beta-globin gene in mice erythroleukemia (MEL) cells].

Our previous works have verified that the beta-globin gene carrying large fragments of erythroid enhancer transferred by retrovirus vector caused the unstable provirus integration and low virus titer in infected cells, but the 36bp enhancer had not this negative effect. In order to circumvent this problem, we inserted the intact beta-globin gene (beta) or partially IVS II deleted beta-globin gene (delta beta) and truncated erythroid enhancer (36bp, 292bp and 341bp) into the N2A retrovirus vector. Recombinants were transfected into psi-2 ecotropic pachaging cells first, then the produced virus were used to infect PA317 amphotropic packaging cells. Virus supernatent from PA317 clonies with high virus titer and intact provirus integration was used to infect MEL cells. RNase protection assay was used to detect the expression of beta-globin gene. Results showed that not only the stable provirus integration and high virus titer of the transferred genes, but also the high levels expression of beta-globin gene carrying 292bp or 341bp erythroid enhancer were got.