gene 2

1. 13. TF TF Cell-specific gene expression Skin cells gene 1 P1 Ex1 Ex2 T I1 I2 Ex3 Skin cell-specific enhancer S gene 2 Ex1 I1 P2 Ex2 Ex3 T I2 I3 Ex4 Neuron-specific enhancer Nerve cells gene 1 P1 Ex1 Ex2 T I1 I2 Ex3 Skin cell-specific enhancer gene 2 Ex1 I1 P2 Ex2 Ex3 T I2 I3 Ex4 Neuron-specific enhancer Cell-specific gene expression: histone pattern! 1. Type of transcription factor expressed in a cell 2. The accessibility of the regulatory region of a gene

2. Signal transduction Steroid hormone activation inhibitor (hsp90) steroid glucocorticoid receptor Nucleus DNA GRE cytoplasm GRE: glucocorticoid response element

3. Signal transduction Interferon-γ activation IFN-γ IFN-γ receptor P P JAK kinase STAT-1 nucleus DNA RE RE: response element IFN: interferon JAK: Janus activated kinase STAT-1: transcription factor cytoplasm

4. 1 siRNA: small interfering RNA RISC: RNAi silencing complex RISC*: activated RISC Slicer: it cleaves mRNA RNase: ribonuclease RNA interference – Dicing Dicer Double-stranded RNA siRNAs (21-23 base pairs) RISC Helicase RISC* (activated) mRNA Slicer RNase

5. 2 siRNA: small interfering RNA RISC: RNAi silencing complex RISC*: activated RISC Slicer: it cleaves mRNA RNase: ribonuclease RNA interference – amplification Dicer Double-stranded RNA siRNAs Dicer mRNA Amplified double- stranded RNA RNA-dependent RNA polymerase many siRNAs