CRISPR meets machine learning

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credit McKylan Mullins

If a donor template is not provided when CRISPR cuts the DNA, broken ends are fixed by natural repairing mechanisms in a way that is considered stochastic and heterogeneous. This makes template-free editing impractical beyond gene disruption, right? Wrong, according to a study published in Nature by Richard Sherwood and colleagues. Continue reading

Do we need a Global Observatory for Gene Editing?

osservatorio globale NatureEveryone knows IPCC, the forum created under the auspices of the United Nations to review the state of knowledge on climate change, draw scenarios on its impact, and compare alternative policies. Does the world need a similar body for the biotech revolution ahead, as claimed by Sheila Jasanoff and J. Benjamin Hurlbut in Nature? Is a Global Observatory on Gene Editing the solution to our CRISPR troubles? We asked a pioneer of gene therapy and a pioneer of gene drives, but also a bioethicist, a political scientist, a social psychologist, a science historian. Continue reading

xCas9: CRISPR gets easy-going

pam sequenceCRISPR needs to anchor itself near a short sequence called PAM to do its job. In the book “Modern Prometheus” (Cambridge University Press) James Kozubek says a PAM is like a shoehorn, where the Cas9 nuclease begins to clasp down to recognize the right site and cut. In order to fit every gene, a super-adjustable shoehorn would be needed. Think of it as the equivalent of a bump key that can open any door. A Broad Institute group led by David Liu has almost reached the goal with xCas9, the new super-adjustable Cas9 variant described in Nature this week. Continue reading

Adding the RNA string to the CRISPR bow

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So far we have learned that CRISPR may turn a faulty gene off by cutting and mutating its sequence. But what if we want to proceed more cautiously and avoid permanent changes to the genome? We could leave the target gene intact but ineffective, by intercepting and destroying the RNA messages with which it gives the wrong orders to the diseased cells. In this way it would be easier to go back if necessary. The good news is that CRISPR is a jack-of-all-trades, well-suited for the task, and the new approach (call it RNA targeting with CRISPR) is going to help to study human biology and diseases. One of the technique pioneer, Feng Zhang, has demonstrated in Nature last week that it can efficiently target RNA in mammalian cells (and also plants), equalizing and even surpassing the performance of the current tool of choice for RNA knockdown (RNA interference). In short, besides advancing its career as DNA editor, CRISPR has also found a second job in the RNA business. Continue reading