AIM: To seek a small interfering RNA ( siRNA ) sequence targeting rat inhibitor of nuclear factor kappa Bα ( IκBα) that can specifically and effectively suppress IκBα mRNA expression of rat ciliary muscles in vivo.METHODS:Three IκBα specific double stranded siRNAs were designed and synthesized. They were transfected into rat A7r5 cells which express IκBα gene. Flow cytometry was used to assess transfected efficiency. The mRNA and protein levels of IκBα were examined by Real Time quantitative polymerase chain reaction ( Real Time-PCR ) and western blot to screen a candidate valid sequence with the highest inhibitory rate. The Cy3 labeled non-specific control siRNA or the candidate valid siRNA was then injected into rat anterior chamber. Distribution of Cy3- siRNA in rat ciliary muscles was viewed by fluorescence microscopy, and the inhibitory effect in vivo of the valid siRNA was identified via Real Time-PCR and immunofluorescence. RESULTS: The suppression effect of the siRNA targeting the CTACGATGACTGTGTGTTT of IκBα gene was most obvious by vitro screening. By anterior chamber injection, this valid siRNA could reach rat ciliary muscles and effectively suppress IκBα gene expression with the highest inhibitory rate of 59. 0% on mRNA level at 24h after RNAi, and 52. 3% on protein level at 72h after RNAi (P<0. 01).CONCLUSION: It proves that the siRNA targeting the CTACGATGACTGTGTGTTT of IκBα gene is the valid sequence to suppress rat IκBα expression of ciliary muscles by RNAi in vivo.%目的：寻找可在体内有效抑制大鼠睫状肌核转录因子资B抑制物α( I资Bα)基因表达的小干扰RNA( siRNA)序列。方法：设计合成3对针对大鼠I资Bα基因的siRNA,体外转染表达I资Bα基因的大鼠A7 r5细胞,通过流式细胞仪检测转染效率,并经 Real Time-PCR 及 western blot 在mRNA及蛋白水平筛选对I资Bα表达抑制率最高的序列。通过前房注射选出的siRNA进行大鼠体内转染,荧光显微镜下观察其在大鼠睫状肌的分布并利用Real Time-PCR及免疫荧光验证其对该部位I资Bα基因沉默的有效性。结果：体外筛选证明针对大鼠 I资Bα基因 CTACGATG ACTGTGTGTTT靶序列的 siRNA 对 I资Bα的表达抑制效果最明显,大鼠前房注射该siRNA可到达睫状肌,并能有效抑制该部位I资Bα基因的表达, I资Bα mRNA水平在转染后24 h降低最明显,抑制率达59.0%,而蛋白水平则在72h达最低,抑制率为52.3%(P<0.01)。结论：针对大鼠I资Bα基因CTACGATGACTGTGTGTTT靶序列的siRNA是对大鼠睫状肌I资Bα基因进行体内RNA干扰的有效序列。
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