OBJECTIVETo investigate the effects of hydrodynamics-mediated RNAi for Mfn2 gene expression in liver and the levels of blood sugar and fat in mice.

METHODSFifty-six male BALB/c mice were randomly divided into normal control group (NC, n = 8), negative control group (HK, n = 24) and transfection group (Mfn2, n = 24) according to random digits table. 1.5 ml plasmid (negative control or Mfn2 shRNA, 75mug for each mouse) diluted into phosphate buffered solution (PBS) was injected into the HK and Mfn2 groups mice via hydrodynamic intravascular injection. Mfn2 mRNA and protein expression in hepatic tissue was detected by RT-PCR and Western-blot 24 hours, 72 hours and 120 hours respectively after injection. At the same time, the levels of fasted blood sugar (FBS) and triglyceride (TG) were measured.

RESULTSCompared with HK mice, the expressions of Mfn2 mRNA (1.00+/-0.03 vs 1.14+/-0.07, t = 4.027, P = 0.007; 1.01+/-0.053 vs 1.18+/-0.07, t = 4.234, P = 0.006) and protein (7.81+/-0.80 vs 8.01+/-0.08, t = 2.941, P = 0.042; 8.05+/-0.15 vs 8.56+/-0.014, t = 4.883, P = 0.039) decreased markedly in Mfn2 mice in 72 and 120 hours after injection. In the fasting state, in 24 hours after injection, FBS in Mfn2 group was significantly lower than that in HK group [(2.65+/-0.70 vs 5.28+/-0.82) mmol/L, t = 6.879, P value less than 0.01] and TG was also significantly higher than that in HK group [(1.96+/-0.32 vs 1.12+/-0.16) mmol/L, t = -6.711, P value less than 0.01]. No statistical differences found between the NC and HK groups for FBS and TG (F = 1.412, P = 0.26; F = 2.711, P = 0.14). The plasma glucose level in Mfn2 mice was significantly higher than that in HK mice [(7.23+/-0.82 vs 5.18+/-0.69) mmol/L, t = 2.050, P value less than 0.01; (7.00+/-0.67 vs 6.05+/-0.76) mmol/L, t = 3.57, P = 0.023] in 72 and 120 hours after injection. However, no differences found between the two groups for blood TG [(1.53+/-0.27 vs 1.37+/-0.18) mmol/L, t = 0.160, P = 0.23; (1.84+/-0.30 vs 1.52+/-0.37) mmol/L, t = 0.330, P = 0.503].

CONCLUSIONThe data indicate that hydrodynamics- mediated RNAi for Mfn2 gene can effectively inhibit the expression of target gene in mice liver in 72 and 120 hours after shRNA administration, and the inhibition of hepatic Mfn2 can induce glycometabolic and fat metabolic disorder.