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Q: What is "CRISPR"?

A: "CRISPR" (pronounced "crisper") stands for Clustered Regularly Interspaced Curt Palindromic Repeats, which are the hallmark of a bacterial defense system that forms the ground for CRISPR-Cas9 genome editing engineering science. In the field of genome engineering, the term "CRISPR" or "CRISPR-Cas9" is oft used loosely to refer to the various CRISPR-Cas9 and -CPF1, (and other) systems that can be programmed to target specific stretches of genetic code and to edit Dna at precise locations, too every bit for other purposes, such every bit for new diagnostic tools. With these systems, researchers can permanently modify genes in living cells and organisms and, in the hereafter, may make it possible to correct mutations at precise locations in the man genome in order to treat genetic causes of disease. Other systems are now available, such equally CRISPR-Cas13's, that target RNA provide alternate avenues for apply, and with unique characteristics that have been leveraged for sensitive diagnostic tools, such as SHERLOCK.

Q: Where do CRISPRs come from?

A: CRISPRs were offset discovered in archaea (and later in bacteria) by Francisco Mojica, a scientist at the University of Alicante in Spain. He proposed that CRISPRs serve as part of the bacterial immune system, defending against invading viruses. They consist of repeating sequences of genetic code, interrupted by "spacer" sequences – remnants of genetic code from past invaders. The organization serves equally a genetic retentiveness that helps the cell detect and destroy invaders (called "bacteriophage") when they return. Mojica'southward theory was experimentally demonstrated in 2007 by a team of scientists led by Philippe Horvath.

In January 2013, the Zhang lab published the first method to engineer CRISPR to edit the genome in mouse and human cells.

For more on many of the scientists and teams who contributed to the understanding and development of the CRISPR system from the initial discovery to the starting time demonstrations of CRISPR-mediated genome editing, visit our CRISPR timeline.

Q: How does the system work?

A: CRISPR "spacer" sequences are transcribed into short RNA sequences ("CRISPR RNAs" or "crRNAs") capable of guiding the organisation to matching sequences of Deoxyribonucleic acid. When the target DNA is found, Cas9 – one of the enzymes produced by the CRISPR system – binds to the DNA and cuts it, shutting the targeted gene off. Using modified versions of Cas9, researchers can activate factor expression instead of cutting the Deoxyribonucleic acid. These techniques permit researchers to study the gene's function.

Research also suggests that CRISPR-Cas9 can be used to target and modify "typos" in the 3-billion-letter sequence of the human genome in an endeavour to treat genetic affliction.

CRISPR
An creative person's depiction of the CRISPR system in action.
Illustration by Stephen Dixon

Q: How does CRISPR-Cas9 compare to other genome editing tools?

A: CRISPR-Cas9 is proving to exist an efficient and customizable culling to other existing genome editing tools. Since the CRISPR-Cas9 system itself is capable of cutting Dna strands, CRISPRs do not need to exist paired with separate cleaving enzymes every bit other tools do. They tin can besides hands exist matched with tailor-made "guide" RNA (gRNA) sequences designed to lead them to their DNA targets. Tens of thousands of such gRNA sequences take already been created and are available to the research community. CRISPR-Cas9 can besides be used to target multiple genes simultaneously, which is some other reward that sets it autonomously from other gene-editing tools.

Q: How does CRISPR-Cpf1 differ from CRISPR-Cas9?

CRISPR-Cpf1 differs in several of import ways from the previously described Cas9, with significant implications for research and therapeutics.

First, in its natural form, the Dna-cut enzyme Cas9 forms a complex with ii small RNAs, both of which are required for the cut action. The Cpf1 system is simpler in that information technology requires only a unmarried RNA. The Cpf1 enzyme is besides smaller than the standard SpCas9, making it easier to evangelize into cells and tissues.

Second, and maybe near significantly, Cpf1 cuts DNA in a different manner than Cas9. When the Cas9 circuitous cuts Dna, information technology cuts both strands at the same place, leaving 'blunt ends' that often undergo mutations as they are rejoined. With the Cpf1 complex the cuts in the two strands are kickoff, leaving short overhangs on the exposed ends. This is expected to help with precise insertion, allowing researchers to integrate a piece of DNA more than efficiently and accurately.

Third, Cpf1 cuts far abroad from the recognition site, meaning that even if the targeted gene becomes mutated at the cut site, it can probable still be re-cutting, allowing multiple opportunities for correct editing to occur.

Fourth, the Cpf1 organization provides new flexibility in choosing target sites. Similar Cas9, the Cpf1 complex must first attach to a short sequence known as a PAM, and targets must be chosen that are next to naturally occurring PAM sequences. The Cpf1 circuitous recognizes very unlike PAM sequences from those of Cas9. This could be an advantage in targeting, for case, the malaria parasite genome and even the homo genome.

Q: What other scientific uses might CRISPR take beyond genome editing?

A: CRISPR genome editing allows scientists to chop-chop create prison cell and animal models, which researchers can utilize to accelerate research into diseases such as cancer and mental illness. In improver, CRISPR is now existence developed as a rapid diagnostic. To help encourage this type of research worldwide, Feng Zhang and his team have trained thousands of researchers in the use of CRISPR genome editing technology through direct education and by sharing more than than forty,000 CRISPR components with academic laboratories around the world.

Source: https://www.broadinstitute.org/what-broad/areas-focus/project-spotlight/questions-and-answers-about-crispr

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