Overexpression of IMP1 in producer cells increased the production of infectious MLV vector in a dose-dependent manner.

The MLV vector producing constructs pCMV-VSVG, pHIT60 and pMA-Luc in a total of 3.6 µg at the ratio of 1.3∶1.3∶1, and 0.01 µg of pRL-TK, a plasmid expressing renilla luciferase, were cotransfected into 293T cells in 10 cm dishes together with 0.4 µg of empty vector, pcDNA4-IMP1 or pcDNA4-IMP3 (A–C), or with the indicated amounts of IMP1 (D–F). At 48 h posttransfection, the virus was harvested to infect 293 cells and the luciferase activities in the producer cells were measured. At 48 h postinfection, the luciferase activity was measured in the recipient cells. (A) (D) The indicated proteins in the producer cells or virions were detected by Western blotting. (B) (E) Firefly luciferase activity normalized by reneilla luciferase activity in the producer cells. (C) (F) Firefly luciferase activity in the recipient cells normalized by reneilla luciferase activity in the producer cells. The data are means ± SD of three independent measurements. *denotes p<0.05, **denotes p<0.01.