CRISPR Cas9 : Définitions, Principe et Applications | PRIX NOBEL DE CHIMIE 2020

Summary

This video introduces the CRISPR-Cas9 system, a revolutionary technique combining microbiology and genetic engineering. It explains how CRISPR, a bacterial immune system, uses repetitive DNA sequences to protect bacteria from viral infections. Researchers Jennifer Doudna and Emmanuelle Charpentier harnessed this system for gene editing, enabling precise alterations in genomes. The video explores CRISPR-Cas9's applications in medical treatments for genetic diseases and infections, as well as potential uses in agriculture. Ethical considerations around its use in human embryos are also addressed, providing a comprehensive overview of this groundbreaking technology.

Takeaways

• 😀 CRISPR-Cas9 is a revolutionary gene-editing technology that combines microbiology and genetic engineering.
• 😀 The history of CRISPR-Cas9 began in 1987 when researchers discovered repetitive sequences in the genome of *E. coli*.
• 😀 These sequences, called CRISPR, were initially thought to be a bacterial immune system against viral infections.
• 😀 In 2007, it was proposed that CRISPR sequences serve as an adaptive immune system for bacteria, protecting them from viral DNA.
• 😀 The CRISPR-Cas9 system includes proteins (Cas) that can cut DNA, helping bacteria fight viral infections.
• 😀 When a virus infects a bacterium, its viral DNA can be stored in the bacterium's genome to fight future infections.
• 😀 Cas9 proteins and guide RNA (gRNA) work together to target and cut specific viral DNA sequences.
• 😀 The discovery of CRISPR-Cas9 in *Streptococcus pyogenes* led to its use in genetic engineering and genome editing.
• 😀 CRISPR-Cas9 allows scientists to modify genes in living organisms, with potential applications in medicine and agriculture.
• 😀 The technology has applications for treating genetic diseases like cystic fibrosis and Duchenne muscular dystrophy, and could help target viruses like HIV.
• 😀 Ethical concerns arise with the use of CRISPR, especially regarding gene editing in humans and embryo modification.

Q & A

What is CRISPR-Cas9 and how does it function in bacteria?

CRISPR-Cas9 is a bacterial defense system that functions as an adaptive immunity mechanism against viral infections. It stores viral DNA sequences in the form of 'spacers' between repetitive DNA sequences in the genome, allowing the bacteria to recognize and defend against subsequent infections by the same virus.

What does CRISPR stand for?

CRISPR stands for 'Clustered Regularly Interspaced Short Palindromic Repeats.' These are DNA sequences that are regularly spaced and palindromic, meaning they can be read forwards and backwards.

How did researchers first discover the role of CRISPR sequences in bacteria?

The role of CRISPR sequences was first identified in 1987 when researchers discovered unusual, repetitive DNA sequences in the genome of *Escherichia coli*. However, it wasn’t until 2007 that it was proposed these sequences functioned as an adaptive immune system to protect bacteria from viral infections.

What are 'spacers' in the context of CRISPR?

'Spacers' are short DNA sequences intercalated between the repetitive CRISPR sequences in bacterial genomes. These spacers correspond to viral DNA, such as bacteriophages, that previously infected the bacteria, effectively serving as a genetic memory of past infections.

How does the CRISPR-Cas9 system recognize viral DNA?

When a bacterial cell is infected by a virus, the CRISPR system uses the stored 'spacer' sequences, which are transcribed into RNA. This RNA guides the Cas9 protein to the viral DNA, where it is cut and destroyed, thereby preventing the virus from replicating.

What are the key components of the CRISPR-Cas9 system used in gene editing?

The key components of the CRISPR-Cas9 gene-editing system are the Cas9 protein, which cuts DNA, and a guide RNA (gRNA), which directs the Cas9 protein to a specific DNA sequence. These components can be engineered to target and modify specific genes in various organisms.

What was the breakthrough contribution of Jennifer Doudna and Emmanuelle Charpentier to CRISPR?

Jennifer Doudna and Emmanuelle Charpentier discovered how to repurpose the CRISPR-Cas9 system for gene editing. They developed a simplified version that uses just the Cas9 protein and a guide RNA, making it an effective tool for precise genetic modifications in many organisms.

What are some potential applications of CRISPR-Cas9 in medicine?

CRISPR-Cas9 has numerous medical applications, including the potential to treat genetic diseases like cystic fibrosis and Duchenne muscular dystrophy. It could also be used to target viruses like HIV, offering new avenues for treatment.

How could CRISPR-Cas9 be applied in agriculture?

In agriculture, CRISPR-Cas9 could be used to genetically modify crops to improve traits such as disease resistance, drought tolerance, or nutritional content. This could lead to more efficient food production and help address challenges like climate change.

What are some ethical concerns surrounding the use of CRISPR-Cas9, particularly in humans?

Ethical concerns about CRISPR-Cas9 primarily focus on its potential use in human germline editing, such as modifying embryos. This raises questions about unintended consequences, genetic inequalities, and the possible creation of 'designer babies.' The technology's use in humans needs careful regulation and ethical consideration.