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Genomic editing presentation
- 2. What is genomic editing? • Genomic editing is the process that scientists can alter a piece of DNA to achieve desirable characteristics • When altering an organism's DNA material can be added, removed or altered at particular locations in the genome.
- 3. What genomic editing used for • Scientists can knock out certain genes to observe the effects and mutations caused by those genes. • With the mapping of the human genome scientists have been able to manipulate the genes of other organisms to produce beneficial products for humans • Farmers have been producing genetically engineered super foods such as potatoes and apples.
- 4. Successful genetic modifications • Glow in the dark kitty using GFP • GFP was inserted along with a gene that blocks FIV. • Generations of cats that glowed had anti-FIV gene
- 5. CRISPR • Clustered regularly interspaced short palindromic repeats (CRISPR) is a family of DNA sequences found in the genome of prokaryotic organisms. • It is a highly precise gene editing tool that is changing cancer research and treatment. • CRISPR allows scientists to alter DNA sequences and modify gene function by knocking out genes.
- 6. How does CRISPR work? • Cas9 recognizes a protospacer- adjacent motif (PAM) upstream or downstream of the target sequence by using a guide RNA and induces double-stranded breaks in the target DNA. • The CRISPR-Cas9 system can be engineered to edit eukaryotic DNA by designing guide RNA complementary to the target sequence.
- 9. Genomic modifications in humans • You Lu and other scientists examined the feasibility and safety of using CRISPR-edited T cells to treat late-stage lung cancer and demonstrated low off target editing rates and no severe treatment-related adverse events indicating is safe clinical use. • They hypothesized T cells edited via CRISPR-CAS9 show enhanced anti-tumor responses against gastric cancer.
- 11. Alternative techniques Zinc finger nucleases First nucleases in genomic editing and found in eukaryotes Transcription activator-like effector nucleases (TALENs) Similar to ZFN, uses DNA binding motifs to direct the same non-specific nuclease to cleave the genome but it recognizes a single nucleotide instead of triple. CRISPR advantages • Target design simplicity - gRNAs designed readily and cheaply • Efficiency -modifications Introduced by directly injecting RNAs encoding Cas protein and gRNA into mouse embryos
- 12. Diseases CRISPR can help • Cystic fibrosis, HIV and Cancer • In 2018 first human trials for CRISPR are approved to treat beta thalassemia • In 2020 there was success from clinical trials • Victoria gray in the first was the first patient to undergo sickle cell disease treatment. • Patients showed improvement in fetal hemoglobin levels in their blood
- 13. Limitations • Potential off-target effects – genotoxicity • Difficult to deliver CRISPR/Cas9 material to mature cells in large numbers • Not 100% efficient, cells might not have genome editing activity • Ethical concern – designer babies
- 14. Link to career • NHS Scientist training Programme • Career in genomics
- 15. To conclude • Genetic modification is newly discovered and has been successful in foods • Techniques such as TALENS, ZFN and CRISPR can help treat diseases • CRISPR poses risks such as off-target effects which cause genotoxicity • Genetic editing still has a long way to go
Editor's Notes
- Resistant to browning
- https://www.smithsonianmag.com/science-nature/the-glow-in-the-dark-kitty-77372763/
- he CRISPR arrays are transcribed and processed to produce CRISPR RNAs (crRNAs) that each contain one spacer and one copy of the adjacent constant region (3). The crRNA then binds a second, invariant RNA, the transactivating RNA (tracrRNA), and the resultant crRNA:tracrRNA complex, in the case of bacterial class II CRISPR/Cas systems, then binds to the CRISPR-associated (Cas) protein Cas9. Once this ribonucleoprotein complex is formed, it is targeted to the genome of the cognate, invading DNA bacteriophage by the sequence complementarity of the spacer sequence to that genome. Once bound, Cas9 cleaves the bacteriophage DNA, resulting in its elimination and thereby blocking productive infection
- The guide RNA has a 20 base pair protospacer motif with flanking homology to the cut site of interest. Cas9 binds to this protospacer motif in the guide RNA, which in turn binds to the site of interest. Cas9 then binds to a protospacer adjacent motif (PAM) in the genomic DNA, and catalyzes a DSB in the DNA at a position three base pairs upstream of the PAM.
- https://www.synthego.com/learn/genome-engineering-history
- https://www.nature.com/articles/s41591-020-0840-5#ref-CR4