Discovery of the CRISPR Gene Editing System
1987 - Yoshizuma Ishiro observes repetitive DNA sequences in E. coli & later in Archaean species.
1992 - Franciso Mojica analyzes these repeats & coins term CRISPR 'clustered regularly interspaced palindromic repeats'
2002 - the DNA repeats are shown to occur near CAS nuclease genes that can unwind & cut dsDNA
next -  DNA sequencing showed that the repeats came from bacteriophage DNA, likley by infection & integration
2007 - P. Hovrath & R. Barrangou of yogurt producer Danisco studying bacteriophage infections of yogurt            bacteria showed infections added new viral spacer DNA & their removal affected ability of yogurt bacteria            to resist infections. The viral DNA made RNA pieces that guided CAS nucleases to attack the invading            DNA and cut it up... 'a kind of bacterial immune system providing resistance to viral infections'.            CRISPR sequenes have subsequently been found throughout microbial life systems.
2008 - 1st CRISPR conference @ Berkeley and speculation grows that the bacterial CRISPR system might be            used to not only target viral DNA for cutting, but any DNA with a "guide sequence".
next
2011 - a. the essentials of how CRISPR works in bacteria are known and Emmanuelle Charpentier identifies an                essential RNA component 'tracrRNA of unknown function.            b. Eva Nogales, Doudna's colleague describes crystalline structure of the molecules            c. V. Siksnys (Vilnius U.) identifies a CAS-9 nuclease as the enzyme that cuts DNA            d. Jennifer Diudna & Emmanuelle Charpentier meet at conference in Puerto Rico and begin a collaboration
2012 - Dounda & Charpentier publish in Science that the system requires 2 RNA structures to have Cas9 make            double strand cuts, a guide crRNA and a tracrRNA, which can be combined in a single transcript to            cleave any DNA target binding sequence with complementarity to a gene, offering a methodology based            on RNA-programmed Cas9 (that has considerable potential for gene-targeted editing applications).
2013 - Feng Zeng of Broad Institute showed that the Doudna methodology worked in mouse and human cells in            culture. By end of 2013 Zeng's group had 64,571 unique CRISPR sequences for some 18,080 Human            genes (80% of the Human genome) with a 50% to 80% effectiveness.
2020 - Jennifer Doudna and Emmanuelle are awarded the Nobel Prize in Chemistry for the development of a            method for genome editing.
current - The CRISPR system is easy to use and editing can today be done in almost any lab. Even CRISPR Kits                are available to edit genes. Addgene ("the Amazon for Plasmids") is a non-profit that distributes                some 60,000 plasmids of various constructs (CRISPRs) to 20,000+ labs in 85 different countries for                researchers to use.                But, to date no CRISPR 'health' products to cure any illness are on the market. The US Patent Office                has 6,000+ CRISPR patent applications pending.
Back
.