Tag Archives: Lucas Harrington

Congratulations to winners of 2020 Nobel Prize for Chemistry: Dr. Emmanuelle Charpentier & Dr. Jennifer A. Doudna (CRISPR-cas9)

It’s possible there’s a more dramatic development in the field of contemporary gene-editing but it’s indisputable that CRISPR (clustered regularly interspaced short palindromic repeats) -cas9 (CRISPR-associated 9 [protein]) ranks very highly indeed.

The technique, first discovered (or developed) in 2012, has brought recognition in the form of the 2020 Nobel Prize for Chemistry to CRISPR’s two discoverers, Emanuelle Charpentier and Jennifer Doudna.

An October 7, 2020 news item on phys.org announces the news,

The Nobel Prize in chemistry went to two researchers Wednesday [October 7, 2020] for a gene-editing tool that has revolutionized science by providing a way to alter DNA, the code of life—technology already being used to try to cure a host of diseases and raise better crops and livestock.

Emmanuelle Charpentier of France and Jennifer A. Doudna of the United States won for developing CRISPR-cas9, a very simple technique for cutting a gene at a specific spot, allowing scientists to operate on flaws that are the root cause of many diseases.

“There is enormous power in this genetic tool,” said Claes Gustafsson, chair of the Nobel Committee for Chemistry.

More than 100 clinical trials are underway to study using CRISPR to treat diseases, and “many are very promising,” according to Victor Dzau, president of the [US] National Academy of Medicine.

“My greatest hope is that it’s used for good, to uncover new mysteries in biology and to benefit humankind,” said Doudna, who is affiliated with the University of California, Berkeley, and is paid by the Howard Hughes Medical Institute, which also supports The Associated Press’ Health and Science Department.

The prize-winning work has opened the door to some thorny ethical issues: When editing is done after birth, the alterations are confined to that person. Scientists fear CRISPR will be misused to make “designer babies” by altering eggs, embryos or sperm—changes that can be passed on to future generations.

Unusually for phys.org, this October 7, 2020 news item is not a simple press/news release reproduced in its entirety but a good overview of the researchers’ accomplishments and a discussion of some of the issues associated with CRISPR along with the press release at the end.

I have covered some CRISPR issues here including intellectual property (see my March 15, 2017 posting titled, “CRISPR patent decision: Harvard’s and MIT’s Broad Institute victorious—for now‘) and designer babies (as exemplified by the situation with Dr. He Jiankui; see my July 28, 2020 post titled, “July 2020 update on Dr. He Jiankui (the CRISPR twins) situation” for more details about it).

An October 7, 2020 article by Michael Grothaus for Fast Company provides a business perspective (Note: A link has been removed),

Needless to say, research by the two scientists awarded the Nobel Prize in Chemistry today has the potential to change the course of humanity. And with that potential comes lots of VC money and companies vying for patents on techniques and therapies derived from Charpentier’s and Doudna’s research.

One such company is Doudna’s Editas Medicine [according to my search, the only company associated with Doudna is Mammoth Biosciences, which she co-founded], while others include Caribou Biosciences, Intellia Therapeutics, and Casebia Therapeutics. Given the world-changing applications—and the amount of revenue such CRISPR therapies could bring in—it’s no wonder that such rivalry is often heated (and in some cases has led to lawsuits over the technology and its patents).

As Doudna explained in her book, A Crack in Creation: Gene Editing and the Unthinkable Power to Control Evolution, cowritten by Samuel H. Sternberg …, “… —but we could also have woolly mammoths, winged lizards, and unicorns.” And as for that last part, she made clear, “No, I am not kidding.”

Everybody makes mistakes and the reference to Editas Medicine is the only error I spotted. You can find out more about Mammoth Biosciences here and while Dr. Doudna’s comment, “My greatest hope is that it’s used for good, to uncover new mysteries in biology and to benefit humankind,” is laudable it would seem she wishes to profit from the discovery. Mammoth Biosciences is a for-profit company as can be seen at the end of the Mammoth Biosciences’ October 7, 2020 congratulatory news release,

About Mammoth Biosciences

Mammoth Biosciences is harnessing the diversity of nature to power the next-generation of CRISPR products. Through the discovery and development of novel CRISPR systems, the company is enabling the full potential of its platform to read and write the code of life. By leveraging its internal research and development and exclusive licensing to patents related to Cas12, Cas13, Cas14 and Casɸ, Mammoth Biosciences can provide enhanced diagnostics and genome editing for life science research, healthcare, agriculture, biodefense and more. Based in San Francisco, Mammoth Biosciences is co-founded by CRISPR pioneer Jennifer Doudna and Trevor Martin, Janice Chen, and Lucas Harrington. The firm is backed by top institutional investors [emphasis mine] including Decheng, Mayfield, NFX, and 8VC, and leading individual investors including Brook Byers, Tim Cook, and Jeff Huber.

An October 7, 2029 Nobel Prize press release, which unleashed all this interest in Doudna and Charpentier, notes this,

Prize amount: 10 million Swedish kronor, to be shared equally between the Laureates.

In Canadian money that amount is $1,492,115.03 (as of Oct. 9, 2020 12:40 PDT when I checked a currency converter).

Ordinarily there’d be a mildly caustic comment from me about business opportunities and medical research but this is a time for congratulations to both Dr. Emanuelle Charpentier and Dr. Jennifer Doudna.

CRISPR-Cas12a as a new diagnostic tool

Similar to Cas9, Cas12a is has an added feature as noted in this February 15, 2018 news item on ScienceDaily,

Utilizing an unsuspected activity of the CRISPR-Cas12a protein, researchers created a simple diagnostic system called DETECTR to analyze cells, blood, saliva, urine and stool to detect genetic mutations, cancer and antibiotic resistance and also diagnose bacterial and viral infections. The scientists discovered that when Cas12a binds its double-stranded DNA target, it indiscriminately chews up all single-stranded DNA. They then created reporter molecules attached to single-stranded DNA to signal when Cas12a finds its target.

A February 15, 2018 University of California at Berkeley (UC Berkeley) news release by Robert Sanders and which originated the news item, provides more detail and history,

CRISPR-Cas12a, one of the DNA-cutting proteins revolutionizing biology today, has an unexpected side effect that makes it an ideal enzyme for simple, rapid and accurate disease diagnostics.

blood in test tube


Cas12a, discovered in 2015 and originally called Cpf1, is like the well-known Cas9 protein that UC Berkeley’s Jennifer Doudna and colleague Emmanuelle Charpentier turned into a powerful gene-editing tool in 2012.

CRISPR-Cas9 has supercharged biological research in a mere six years, speeding up exploration of the causes of disease and sparking many potential new therapies. Cas12a was a major addition to the gene-cutting toolbox, able to cut double-stranded DNA at places that Cas9 can’t, and, because it leaves ragged edges, perhaps easier to use when inserting a new gene at the DNA cut.

But co-first authors Janice Chen, Enbo Ma and Lucas Harrington in Doudna’s lab discovered that when Cas12a binds and cuts a targeted double-stranded DNA sequence, it unexpectedly unleashes indiscriminate cutting of all single-stranded DNA in a test tube.

Most of the DNA in a cell is in the form of a double-stranded helix, so this is not necessarily a problem for gene-editing applications. But it does allow researchers to use a single-stranded “reporter” molecule with the CRISPR-Cas12a protein, which produces an unambiguous fluorescent signal when Cas12a has found its target.

“We continue to be fascinated by the functions of bacterial CRISPR systems and how mechanistic understanding leads to opportunities for new technologies,” said Doudna, a professor of molecular and cell biology and of chemistry and a Howard Hughes Medical Institute investigator.

DETECTR diagnostics

The new DETECTR system based on CRISPR-Cas12a can analyze cells, blood, saliva, urine and stool to detect genetic mutations, cancer and antibiotic resistance as well as diagnose bacterial and viral infections. Target DNA is amplified by RPA to make it easier for Cas12a to find it and bind, unleashing indiscriminate cutting of single-stranded DNA, including DNA attached to a fluorescent marker (gold star) that tells researchers that Cas12a has found its target.

The UC Berkeley researchers, along with their colleagues at UC San Francisco, will publish their findings Feb. 15 [2018] via the journal Science’s fast-track service, First Release.

The researchers developed a diagnostic system they dubbed the DNA Endonuclease Targeted CRISPR Trans Reporter, or DETECTR, for quick and easy point-of-care detection of even small amounts of DNA in clinical samples. It involves adding all reagents in a single reaction: CRISPR-Cas12a and its RNA targeting sequence (guide RNA), fluorescent reporter molecule and an isothermal amplification system called recombinase polymerase amplification (RPA), which is similar to polymerase chain reaction (PCR). When warmed to body temperature, RPA rapidly multiplies the number of copies of the target DNA, boosting the chances Cas12a will find one of them, bind and unleash single-strand DNA cutting, resulting in a fluorescent readout.

The UC Berkeley researchers tested this strategy using patient samples containing human papilloma virus (HPV), in collaboration with Joel Palefsky’s lab at UC San Francisco. Using DETECTR, they were able to demonstrate accurate detection of the “high-risk” HPV types 16 and 18 in samples infected with many different HPV types.

“This protein works as a robust tool to detect DNA from a variety of sources,” Chen said. “We want to push the limits of the technology, which is potentially applicable in any point-of-care diagnostic situation where there is a DNA component, including cancer and infectious disease.”

The indiscriminate cutting of all single-stranded DNA, which the researchers discovered holds true for all related Cas12 molecules, but not Cas9, may have unwanted effects in genome editing applications, but more research is needed on this topic, Chen said. During the transcription of genes, for example, the cell briefly creates single strands of DNA that could accidentally be cut by Cas12a.

The activity of the Cas12 proteins is similar to that of another family of CRISPR enzymes, Cas13a, which chew up RNA after binding to a target RNA sequence. Various teams, including Doudna’s, are developing diagnostic tests using Cas13a that could, for example, detect the RNA genome of HIV.

infographic about DETECTR system

(Infographic by the Howard Hughes Medical Institute)

These new tools have been repurposed from their original role in microbes where they serve as adaptive immune systems to fend off viral infections. In these bacteria, Cas proteins store records of past infections and use these “memories” to identify harmful DNA during infections. Cas12a, the protein used in this study, then cuts the invading DNA, saving the bacteria from being taken over by the virus.

The chance discovery of Cas12a’s unusual behavior highlights the importance of basic research, Chen said, since it came from a basic curiosity about the mechanism Cas12a uses to cleave double-stranded DNA.

“It’s cool that, by going after the question of the cleavage mechanism of this protein, we uncovered what we think is a very powerful technology useful in an array of applications,” Chen said.

Here’s a link to and a citation for the paper,

CRISPR-Cas12a target binding unleashes indiscriminate single-stranded DNase activity by Janice S. Chen, Enbo Ma, Lucas B. Harrington, Maria Da Costa, Xinran Tian, Joel M. Palefsky, Jennifer A. Doudna. Science 15 Feb 2018: eaar6245 DOI: 10.1126/science.aar6245

This paper is behind a paywall.