Progress in the use of CRISPR–Cas9 for human germline editing highlights some pressing ethical considerations for research on embryos.
Researchers the world over are fast adopting CRISPR-Cas9 to tinker with the genomes of humans, viruses, bacteria, animals and plants. Nature brings together research, reporting and expert opinion to keep you abreast of the frontiers of gene editing.
The quiet revolutionary: How the co-discovery of CRISPR explosively changed Emmanuelle Charpentier’s life
The microbiologist spent years moving labs and relishing solitude. Then her work on gene-editing thrust her into the scientific spotlight.
Jennifer Doudna, a pioneer of the revolutionary genome-editing technology, reflects on how 2015 became the most intense year of her career — and what she's learnt.
Rumours of germline modification prove true — and look set to reignite an ethical debate.
The real power of the biological tool lies in exploring how genomes work.
In wake of paper describing genetic modification of human embryos, scientists disagree about ethics.
Gene-editing pioneers prepare for next stage of intellectual-property disputes in the United States and Europe.
Precision tools expand the number of ‘base editors’ available for manipulating DNA and RNA.
A method for precisely editing genes in human embryos hints at a cure for a blood disease.
Gene-edited embryos enable researchers to unpick role of a crucial gene, with more studies likely to follow.
One gene draws the lines while a second fills in the colours.
Alternative explanations challenge whether technique actually fixed a genetic mutation as claimed.
Gene-editing experiment pushes scientific and ethical boundaries.
Microbial immune system can encode movies in bacterial genomes.
Geneticists harness two mutations — each cherished by breeders, but detrimental when combined — to improve on 10,000 years of tomato domestication.
Scientists face tough decisions when the latest gene-editing findings don’t match up with the results of other techniques.
The European Union is dragging its feet on gene-editing rules and scientists should push the issue.
Easy gene alterations in weird creatures make CRISPR a killer app for evolutionary developmental biology.
The popular technique has limitations that have sparked searches for alternatives.
Gene-editing technique to treat lung cancer is due to be tested in people in August.
The technique's first test in people could begin as early as the end of the year.
Study used CRISPR technology to introduce HIV-resistance mutation into embryos.
Decision could determine who profits from the gene-editing technique in future.
Where did it come from? How do organisms use it without self-destructing? And what else can it do?
The CRISPR–Cas9 patent battle demonstrates how overzealous efforts to commercialize technology can damage science, writes Jacob S. Sherkow.
The soaring popularity of gene editing has made celebrities of the principal investigators who pioneered the field — but their graduate students and postdocs are often overlooked.
Birds and bees are just the beginning for a burgeoning technology.
In the fierce debate about CRISPR gene editing, it’s time to give patients a voice.
The real power of the biological tool lies in exploring how genomes work.
A powerful gene-editing technology is the biggest game changer to hit biology since PCR. But with its huge potential come pressing concerns.
Democratically weighing up the benefits and risks of gene editing and artificial intelligence is a political endeavour, not an academic one, says Daniel Sarewitz.
Heritable human genetic modifications pose serious risks, and the therapeutic benefits are tenuous, warn Edward Lanphier, Fyodor Urnov and colleagues.
Research & Review
Genome editing could be applied to correct disease-causing mutations in human embryos, but concerns about efficacy and safety are paramount. Shoukhrat Mitalipov and colleagues use CRISPR–Cas9 to correct a heritable cardiomyopathy mutation in human embryos. By optimizing the experimental conditions, the authors show very reduced mosaicism, and report that for this heterozygous mutation, CRISPR–Cas9-induced breaks seem to be preferentially repaired using the wild-type allele as a template in human embryos. The results advance our understanding of the promises and challenges of editing the human germline.
CRISPR–Cas systems provide defence against invasive genetic elements in prokaryotes. They function by detecting and degrading invader transcripts, mainly through RNA-guided recognition and interference. Csm6 is a CRISPR-associated ribonuclease known to degrade invasive transcripts, but how its activity is regulated by invader sensing was unknown. Here, the authors find that Csm6 is activated by a cyclic oligoadenylated second messenger generated by Cas10 activity within the type III interference complex. This novel mechanism of CRISPR interference regulation, which resembles an aspect of mammalian innate immunity, expands the toolkit of prokaryotic immunity strategies.
It is difficult to establish cell division history and lineage relationships for tissues that are not easily accessed. DNA barcoding approaches can provide this information, but do not offer spatial data. This collaboration between the labs of Long Cai and Michael Elowitz harnesses the power of CRISPR/Cas9-mediated mutagenesis and multiplexed single-molecule RNA fluorescence hybridization (smFISH) to build a new tool, termed MEMOIR, which they use to follow mouse embryonic stem cell divisions. MEMOIR gives access to lineage information in situ and at the single-cell level, while at the same time monitoring changes in gene expression state.
The CRISPR–Cas9 nucleases now widely used in gene editing can be readily customized, but can also induce substantial genome-wide off-target mutations at sequences that resemble the on-target site. Keith Joung and colleagues report a high-fidelity variant of Cas9 from Streptococcus pyogenes that shows on-target activities comparable to the wild-type enzyme, but with off-target events that are undetectable by genome-wide break capture and targeted sequencing methods.
The protozoan parasite Cryptosporidium is a major cause of diarrhoeal disease in young children but until now it has been difficult to study and there is currently no vaccine and only a single drug (nitazoxanide) available to counter the infection. Here Boris Striepen and colleagues describe a robust genetic system for cryptosporidiosis. They genetically modify Cryptosporidium parvum by optimizing transfection of sporozoites using a CRISPR/Cas9 system, to generate stable transgenic lines suitable for in vitro and in vivo drug screening. Using this system they knockout the gene encoding thymidine kinase which increases susceptibility to trimethoprim, an antimalarial drug to which wild-type Cryptosporidium is resistant.
The once fanciful idea that bacteria might have immunological memory became accepted fact with the discovery that the CRISPR–Cas gene loci evolve rapidly to acquire short phage sequences, or spacers, which then integrate between CRISPR repeats and constitute a record of phage infection. These spacers are transcribed into small CRISPR RNAs (crRNAs) that are used to target the DNA of invading viruses. Two papers published in this issue of Nature describe molecular details about how bacteria create a DNA memory of the invading virus. Jennifer Doudna and colleagues show that the purified Escherichia coli Cas1–Cas2 complex integrates oligonucleotide DNA substrates into acceptor DNA in a manner similar to retroviral integrases and DNA transposases. Cas1 is the catalytic subunit, while Cas2 increases integration activity; together they form the minimal machinery required for spacer acquisition. Luciano Marraffini and colleagues show that in the type II CRISPR–Cas system of Streptococcus pyogenes, the Cas9 nuclease that inactivates invading viral DNA using the crRNA as a guide is also required for the incorporation of new spacer sequences, by a yet to be determined mechanism.
The CRISPR-Cas9 system has emerged as a powerful tool for genome editing and transcriptional regulation of specific genes. Feng Zhang and colleagues have successfully modified the system to specifically and potently activate endogenous gene transcription on a genome-wide scale, such that it can be used for large-scale functional genomics screens. Application to a genome-wide screen of melanoma cells for genes which when overexpressed can confer resistance to a BRAF inhibitor demonstrates the feasibility of such screens, and also led to the discovery of potential new resistance mechanisms.
A bacterial enzyme that uses guide RNA molecules to target DNA for cleavage has been adopted as a programmable tool to site-specifically modify genomes of cells and organisms, from bacteria and human cells to whole zebrafish.