Selection of the most effective small interfering RNA which inhibits the expression of TLR4 in microglial cells and detection of the cytotoxicity of transfection complex

Aim To pick out the siRNA which could most effectively inhibit the expression of TLR4 in microglial cells and to detect the cytotoxicity of the transfection complex.Methods Five siRNAs were chemicaly synthesized:four of them were used to inhibit TLR4 expression in microglial cells,the rest was fluorescence-labeled mismatch siRNA as a nagative control.They were all transfected into microglial cells,respectively.TLR4 mRNA was detected 24 h after transfection by RT-PCR and its protein expression was observed by Western blot 48 h later.The cytotoxicity of complex was detected using MTT.Results ① The transfection rate was high enough in microglial cells with siRNA(40 pmol)and LipofectamineTM 2000(1 μl).② The TLR4 siRNA pool reduced TLR4 mRNA by 85%(siRNA439),73%(siRNA312),67%(siRNA1495)and 33%(siRNA2062)respectively compared with mismatch siRNA-treated group 24 h after transfection in a microglial cell line.③ The TLR4 siRNA439 was the most effective siRNA(P0.01).④ The cell survival rates were above 85% in the groups of LipofectamineTM 2000 1 μl compound less than 40 nmol·L-1 siRNA.Conclusions ① The TLR4 siRNA439 can inhibit TLR4 expression most effectively in microglial.② 40 nmol·L-1 siRNA and 1 μl LipofectamineTM 2000 have low cytotoxicity,which are suitable for transfection.