1. Lecture 16 – Overview of sRNA Signaling BIOL 5190/6190 Cellular & Molecular Singal Transduction Prepared by Bob Locy Last modified -13F

2. Introductory Brief History of sRNAs Bacterial – riboswitches Eukaryotes – miRNA synthesis & function Plant paradigm Animal paradigm siRNA synthesis & function Plant paradigm Animal paradigm

3. Introductory Brief History of sRNAs lin-4 – C. Elegans in 1993 – turned out to be the first small regulatory RNA to be discovered in eukaryotes. Mutant with developmental defects – Animals look terrible, elogated growth, larval skin, stop molting, apparently partial larval growth arrest Independently, RNA interference (RNAi) was discovered RNAi involved in control of viral pathogenesis, and artificial RNAi for study of gene regulation. Ultimately demonstrated that “natural” RNAi was viable regulatory process, and The discovery of multiple small regulatory RNAs in eukaryotes, and post transcriptional gene silencing, translational gene silencing, and transcriptional gene silencing.

4. Introductory Brief History of sRNAs RNAi – Post transcriptional gene silencing. Originally discovered in transgenic plants, as antisense knockdown of transcription Led to the discovery of hairpins as RNAi agents Ultimately, found natural antisense constructs, and naturally produced hairpins - miRNAs

7. Module 04: Animal miRNA biogenesis Cell Signalling Biology - Michael J. Berridge - www.cellsignallingbiology.org - 2012 Cell Signalling Biology - Michael J. Berridge - www.cellsignallingbiology.org - 2012

8. Animal miRNA Function - Overview The task of establishing microRNA properties and function of individual miRs is ongoing and already there are indications that each miR can modulate the activity of up to 100 mRNAs to influence a large number of key biological processes:microRNA properties and function Maintenance of embryonic stem (ES) cell pluripotency. MicroRNA modulation of cell-cycle regulatory mechanisms p53 functions and microRNAs MicroRNA regulation of differentiation Differentiation of cardiac cells Differentiation of smooth muscle cells Cell proliferation Apoptosis Stress responses. MicroRNA dysregulation and cancer

9. Module 11: Cell Proliferation

10. siRNAs Short (small) Interfering RNAs – siRNAs NOT miRNAs, produced by different pathways, have different functions ARE dsRNA-produced, are non-coding RNAs with regulatory functions PTGS TGS epigenetics Usually does not involve hairpin Usually does involve an RNA-dependent RNA polymerase May be cut by same RNAse III type proteins, but may be isoforms with miRNA cutters Load into RISC complexes

11. siRNAs Animals piRNAs – Piwi-interacting siRNAs endo-siRNAs Plant Repeat-associated siRNA – ra-siRNA Trans-acting siRNA – ta-siRNA Phased secondary – siRNA – pha-siRNA cis natural antisense siRNA - cis-NAT-siRNA trans natural antisense siRNA - trans-NAT-siRNA

12. Module 11: miRNA Function – Embryonic Stem Cell miRNA