1. MicroRNA genes Ka-Lok Ng Department of Bioinformatics Asia University

2. Types of RNA Introduction

3. miRNA gene  pri-miRNA (stem-loop structure) processed by Drosha  pre-miRNA (65~90 bp) carried by Exportin 5 to cytoplasm  mature miRNA (20~25 bp) is generated by the RNaseIII type enzyme Dicer  directed by RISC to the miRNA target  mRNA cleavage or impede its translation into protein Introduction

4. a : Exonic miRNAs in non-coding transcripts b : Intronic miRNAs in non-coding transcripts c : Intronic miRNAs in protein-coding transcripts Kim (2005) Nature 376

5. miRNA Registry A searchable database of published miRNA sequences and annotation.

6. miRNA gene prediction protocol Assumption – miRNA genes form a gene family （ 1 ） MFE ：＜ -25 kcal. （ 2 ） hairpin ： 3~20 nt. （ 3 ） stem length ： 16~25 nt. （ 4 ） loop ： 1~20 nt. （ 5 ） sequence length ： 60~90 nt. （ 6 ） bulge size ：＜ 20 nt Modify pre-miRNA sequence MFE, hairpin structure Align with known pre-miRNA sequences, and MSA pre-miRNA motifs