Construction of lentiviral vector for late endosomal/lysosomal adaptor, mitogen-activated protein kinase and mammalian target of rapamycin activator 2 interference and its role on inflammatory factor secretion of macrophages

Objective To construct lentiviral vector of late endosomal/lysosomal adaptor, mitogen-activated protein kinase and mammalian target of rapamycin activator 2 (lamtor2) gene, and to explore its regulatory role on inflammatory response of macrophages after Klebsiella pneumoniae infection. Methods Two pairs of mouse lamtor2 short hairpin RNA (shRNA) were designed and sub-cloned into PLKO.1-puro to construct lentiviral vector, and were transfected into the murine RAW264.7 macrophage. There were two experimental groups including pLKO.1-puro shlamtor 2-1(sh1 group) and pLKO.1-puro shlamtor 2-2 (sh2 group), and the RAW264.7 cells transfected with non-treated pLKO.1-puro was set as control. The expession of lamtor2 were detected by real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot. The levels of inflammatory factors including interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α secreted by the cells were detected by RT-qPCR. T test was used for comparison between groups. Results The recombinant lentiviral vector PLKO.1-shlamtor 2 transfected RAW264.7 cells successfully. The relative expressions of lamtor2 mRNA in the control group, the sh1 group and the sh2 group were 1.000±0.000, 0.596±0.125 and 0.120±0.080, respectively. The expression of lamtor2 in the sh2 group was significantly lower than that in the sh1 group (t=3.399, P=0.015), and they were both significantly lower than the control group (t=3.333 and 9.734, respectively, both P< 0.05). After infection with Klebsiella pneumoniae, expression levels of IL-1β (t=15.20), IL-6 (t=43.30) and TNF-α (t=12.67) were significantly higher than those in the control group (all P<0.01). Conclusion The lentiviral vector of lamtor2 can stably down-regulate the expression of lamtor2 gene in macrophages through RNA interference mechanism, which has a significant effect on the secretion of inflammatory factors of macrophages that are infected with Klebsiella pneumoniae. Key words: Macrophages; Klebsiella pneumoniae; Gene silencing; shRNA