据美国匹兹堡大学癌症研究中心的科学家的研究发现，之前一直被当作是“垃圾RNA(junk RNA)”的细胞内小片段RNA实际上是一种非常稳定的分子，或许在细胞代谢过程中发挥重大作用。
这项发现发表在上周Journal of Virology网络版上，是首个对小分子RNA——unusually small RNAs(usRNAs)的研究，usRNA或将成为一种新型的用于疾病诊断的生物标记物或新的治疗靶点。
近些年，科学家发现的小RNA一般长度都超过20个核苷酸。而在该研究中，研究人员发现，长度仅为15个核苷酸的RNA实际上是一种可以在不同组织中生成小分子RNA，这类RNA非常稳定，并且重复性高，具有可再生能力，所表现出多样性远远超过所有其它的长片段的RNA。
研究人员利用的是卡波西肉瘤相关的疱疹病毒(Kaposi sarcoma-associated herpesvirus)，这种病毒所产生的usRNA能够控制人体蛋白质的产生。研究人员利用计算机技术以及实验工具对usRNAs进一步研究发现，这类约只有15个核苷酸长度的RNA有些有趣的特征。许多usRNA能与参与小RNA调节通路的蛋白质相互作用；一些usRNA链的一个末端具有高特异性的核苷酸。
这项研究表明，usRNA参与了细胞的生物学过程。Dr. John强调，这类小RNA或将成为诊断疾病有用的工具，因此有必要对其进行深入研究。（生物谷Bioon.com）
生物谷推荐原始出处：
J. Virol. doi:10.1128/JVI.01325-09
Characterization of viral and human RNAs smaller than canonical microRNAs
Zhihua Li, Sang Woo Kim, Yuefeng Lin, Patrick S. Moore, Yuan Chang, and Bino John
University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Molecular Virology Program, Hillman Cancer Center, 5117 Centre Avenue, Pittsburgh, PA 15213, USA
Recently identified small (20 to 40 bases) RNAs such as microRNAs (miRNAs) and endogenous siRNAs participate in important cellular pathways. In this report, we systematically characterize several novel features of human and viral RNA products smaller than miRNAs. We find that Kaposi sarcoma-associated herpesvirus K12-1 miRNA (23 bases), associates with a distinct, unusually small (17 bases) RNA (usRNA) that can effectively downregulate a K12-1 miRNA target, human RAD21, suggesting that stable degradation-like products may also contribute to gene regulation. High-throughput sequencing reveals a diverse set of human miRNA-derived usRNAs and other non-miRNA-derived usRNAs. Human miRNA-derived usRNAs preferentially match to 5' ends of miRNAs, and are also more likely to associate with the siRNA effector protein Ago2, than Ago1. Many non-miRNA-derived usRNAs associate with Ago proteins and also frequently contain C-rich 3'-specific motifs that are overrepresented in comparison to piRNAs and TSSa-RNAs. We postulate that approximately 30% of usRNAs could have evolved to participate in biological processes including gene-silencing.
