World of small RNAs: from ribozymes to siRNA and miRNA.

RNAs, besides bridging genetic information to proteins, the major determinants of bio-structures and functions, serve as active regulators of gene expression. Initiated nearly 20 years ago with ribozymes (the small RNAs with catalytic activity providing fine tuning of gene expression and function, used as molecular scissors and tools for gene discovery), an era of more complex and coordinated gene regulation by small RNAs, siRNA, and miRNA has recently started. Simple nucleotide complementarity results in highly ordered and regulated events, such as assembly of RNA and proteins, resulting in gene silencing either by mRNA degradation or suppression of translation. This article reviews our contributions to the understanding of structure, the function of small RNAs, their use in biotechnology, and the understanding of phenotypes such as apoptosis, metastasis, and differentiation.