Abstract: Objective To construct and identify a lentiviral vector carrying mouse Krüppel-like factor 4 (KLF4) gene, and establish RAW264.7 cell line of peritoneal macrophages that over-expressed KLF4. Methods KLF4 gene was cloned using the measure of polymerase chain reaction (PCR). Then the recombinant transfer vector pLVX-KLF4 (pLVX-KLF4- mCMV-ZsGreen-PGK-Puro) was constructed. The pLVX-KLF4 was confirmed through PCR, restriction enzyme digestion and sequencing. The correct recombinant transfer vector together with its two helper virus vectors (psPAX2 and pMD2.G) were cotransfected into the 293T cells by Lipofectamine® 3000. The supernatant of 293T was harvested to infect RAW264.7 cells. Flow cytometry (FCM) was used to test the viral titer of the expression level of green fluorescent protein. The expression of KLF4 mRNA in RAW264.7 cells was measured by real-time PCR. Results The restriction enzyme digestion, PCR and sequencing confirmed that the transfer lentiviral vector pLVX-KLF4 was constructed successfully. KLF4 mRNA was overexpressed in Lenti-KLF4 transfected RAW264.7 cells than that of wild type RAW264.7 cells (P＜0.05). In transfected RAW264.7 cells, KLF4 mRNA was over-expressed (P＜0.05). The recombinant lentivirus of KLF4（Lenti-KLF4）titer was 2.05×108 TU/mL measured by FCM．The flow cytometry results showed that the S phase fraction was prolonged and G0/G1 was arrested in the over-expressed KLF4 of RAW264.7 cells. The EdU showed that the up-regulated expression of KLF4 gene stimulated the proliferation of RAW264.7 cells. Conclusion The recombinant lentiviral vector, which can effectively express KLF4 mRNA, has been successfully constructed. The up-regulated KLF4 gene may increase the proliferation of RAW264.7 cells.

Key words: Krüppel-like transcription factors, lentivirus infections, genetic vectors, cell cycle, cell proliferation , Krüppel-like factor 4