Haupenthal Jörg, Baehr Christina, Kiermayer Simone, Zeuzem Stefan, Piiper Albrecht
Department of Internal Medicine II, University of Saarland, D-66421 Homburg/Saar, Germany.
Biochem Pharmacol. 2006 Feb 28;71(5):702-10. doi: 10.1016/j.bcp.2005.11.015. Epub 2006 Jan 10.
Small interfering RNAs (siRNA), RNA duplexes of approximately 21 nucleotides, offer a promising approach to specifically degrade RNAs in target cells by a process termed RNA interference. Insufficient in vivo-stability is a major problem of a systemic application of siRNAs in humans. The present study demonstrated that RNAse A-like RNAses degraded siRNAs in serum. The susceptibility of siRNAs towards degradation in serum was strongly enhanced by local clustering of A/Us within the siRNA sequence, i.e. regions showing low thermal stability, most notably at the ends of the molecule, and by 3'-overhanging bases. Importantly, inhibition of RNAse A family enzymes prevented the degradation and loss of silencing activity of siRNAs in serum. Furthermore, the degradation of siRNAs was considerably faster in human than in mouse serum, suggesting that the degradation of siRNAs by RNAse A family enzymes might be a more challenging problem in a future therapeutic application of siRNAs in humans than in mouse models. Together, the present study indicates that siRNAs are degraded by RNAse A family enzymes in serum and that the kinetics of their degradation in serum depends on their sequence. These findings might be of great importance for a possible future human therapeutic application of siRNAs.
小干扰RNA（siRNA）是一种约21个核苷酸的RNA双链体，它为通过一种称为RNA干扰的过程特异性降解靶细胞中的RNA提供了一种有前景的方法。体内稳定性不足是siRNA在人体中全身应用的一个主要问题。本研究表明，类似核糖核酸酶A的核糖核酸酶会在血清中降解siRNA。siRNA序列中A/U的局部聚集，即显示低热稳定性的区域，最显著的是在分子末端，以及3'端突出碱基，会大大增强siRNA在血清中被降解的敏感性。重要的是，抑制核糖核酸酶A家族酶可防止血清中siRNA的降解和沉默活性的丧失。此外，siRNA在人血清中的降解速度比在小鼠血清中快得多，这表明在未来siRNA用于人体治疗时，核糖核酸酶A家族酶对siRNA的降解可能比在小鼠模型中是一个更具挑战性的问题。总之，本研究表明siRNA在血清中被核糖核酸酶A家族酶降解，并且它们在血清中的降解动力学取决于其序列。这些发现可能对未来siRNA在人体治疗中的应用具有重要意义。
