Takasaki Shigeru
Toyo University, 1-1-1 Izumino Itakura-machi, Ora-gun Gunma, 374-0193, Japan,
Methods Mol Biol. 2015;1218:375-413. doi: 10.1007/978-1-4939-1538-5_24.
MicroRNAs (miRNAs) are small noncoding RNA molecules thought to play an important role in regulating gene expression. Although knowledge of the biological functions of most miRNAs is still limited, miRNAs are thought to regulate the gene expression in various diseases and embryo development. In this chapter, the roles of miRNAs in human cancers are first examined from the viewpoint of up- and downregulation. Oncogenic miRNAs are involved in the overexpression/upregulation of cancers, whereas suppressive miRNAs are involved in the underexpression/downregulation of cancers. Statistical analysis of the positional nucleotide occurrence features of miRNAs revealed differences between the positional nucleotide occurrences of oncogenic and suppressive miRNAs. A miRNA gene-silencing score was then defined on the basis of the higher and lower levels of the statistical significances of positional nucleotides. Since the miRNA scores were closely related to miRNA frequencies, a method using the scores and nucleotide frequencies to distinguish whether a new miRNA is oncogenic or suppressive is proposed. This chapter also describes the roles of miRNAs in development. As miRNAs can act as cis-regulatory elements in the early embryonic development of Drosophila melanogaster, it is proposed that they mediate signal transduction between genes.
微小RNA（miRNA）是一类小的非编码RNA分子，被认为在调节基因表达中发挥重要作用。尽管大多数miRNA的生物学功能的知识仍然有限，但miRNA被认为在各种疾病和胚胎发育中调节基因表达。在本章中，首先从上调和下调的角度研究miRNA在人类癌症中的作用。致癌miRNA参与癌症的过表达/上调，而抑制性miRNA参与癌症的低表达/下调。对miRNA的位置核苷酸出现特征的统计分析揭示了致癌性和抑制性miRNA的位置核苷酸出现之间的差异。然后根据位置核苷酸统计显著性的高低水平定义了一个miRNA基因沉默分数。由于miRNA分数与miRNA频率密切相关，因此提出了一种使用分数和核苷酸频率来区分新miRNA是致癌性还是抑制性的方法。本章还描述了miRNA在发育中的作用。由于miRNA可以在黑腹果蝇的早期胚胎发育中作为顺式调节元件，因此有人提出它们介导基因之间的信号转导。
