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The Many Unsung Breakthroughs of CRISPR

By 08.11.2022

It’s tempting to imagine scientific progress as a series of individual “breakthroughs” punctuating the monotony of everyday research. But breakthrough moments are the culmination of the work of countless scientists in labs and institutions all over the world, answering their own pressing questions. Over the course of each small discovery, these scientists combine their collective research insights to pose even bigger questions that can change the landscape of their fields.

CRISPR-Cas9 gene editing technology was not the product of a single “Eureka” moment. It was a dialogue decades in the making, built upon generations of scientific developments in and out of the lab.

DNA and genome editing

Scientists analyzing DNA helix and editing genome within organisms, CRISPR technology

 

An Insight to an Unseen Struggle

CRISPR, or clustered regularly interspaced short palindromic repeats, refers to a series of DNA sequences found in prokaryotic organisms that forms the foundation of modern gene editing.

As of this writing, researchers are using CRISPR to develop therapies for a variety of diseases and degenerative disorders. CRISPR provided an invaluable evolutionary benefit to other organisms even before it was sequenced or first observed by scientists.

Bacteria are outnumbered by bacteriophages – viruses that infect and replicate within bacteria or archaea – by a factor of at least 10 to 1.1 With those odds, prokaryotes like bacteria and archaea need to adapt.

Over time, prokaryotes evolved to carry DNA sequences also found in the bacteriophages that frequently infect them. These sequences (which we now call CRISPR) and the homologous gene sets that accompany them (which we now call CRISPR-Cas) allow prokaryotes to identify and resist bacteriophage infection. These immune response mechanisms prevent prokaryotes from being overrun.

However, they also encourage genetic diversity in their would-be infiltrators.2 Optimal mutations in the genome may allow bacteriophages to overcome the CRISPR immune response. This can limit the population growth of prokaryotes.3

The persistent push and pull of these ancient microorganisms may predate modern human civilization, with countless unrecorded evolutionary “breakthroughs” that may have posed global consequences for ancient life.

Nonetheless, the potential applications of CRISPR, phage therapy and other treatments derived from these organisms mean this timeless struggle may pose unique opportunities for future, unrealized breakthroughs.

A Question Answered with Another Question

Fast forward a few millennia or so to the mid-1980’s, when molecular biologist Yoshizumi Ishino was working to identify the role of a specific protein found in E-coli bacteria.4 In answering this question, Ishino soon came upon another: why was he finding the same repeating sequence in so many different clones?

Ishino had no way of knowing he had just stumbled onto the bedrock of modern gene editing. Unfortunately, the sequences proved too difficult to read precisely with technology available in the 80’s and he had to move on.

However, Ishino’s question lingered in the minds of the larger scientific community for years. As the technology to characterize the repeating sequences developed, so did interest in their potential purpose.

In 1992, scientist Francisco Mojica was working on his thesis at the University of Alicante. Mojia sequenced the DNA of halophilic microorganisms and found regularly spaced repeats (later known as “spacers”).5

After reviewing the research Ishino’s team had published on this repeating sequencing, Mojica’s team theorized that these segments served a critical purpose in these organisms.

Mojica said, “The size of the genome of prokaryotes is very limited. They cannot allow themselves any luxuries.”6

In 2001, Mojica was contacted by another team who were using these repeating sequences to identify Mycobacterium tuberculosis. Recognizing the potential relevance of this new discovery, both teams agreed a common terminology was needed for the global scientific community. They settled on CRISPR, for “clustered regularly interspaced short palindromic repeats”.7

A Language for Progress

Coming to consensus on shared terminology is more than a mere clerical convenience.

Scientific classification may not inspire much poetry – if there’s a draft of Romeo & Juliet where Romeo says “A rosa arvensis by any other name would smell as sweet,” it never made it to the stage – but terminology that is specific and distinct is critical for an international scientific community.

A consensus on scientific vocabulary enables scientists to navigate the body of work in their respective fields, regardless of where the work is published. It also allows scientists to find each other.

In the 1990’s, scientists in the US and Netherlands were studying the mechanisms by which RNA may “quell” or “silence” certain genes, such as those that govern pigmentation in a flower.8

By 1998, the term RNAi, for Ribonucleic Acid Interference, was presented to the scientific community.9

In 2006, Dr. Jillian Banfield entered “RNAi and UC Berkeley” into a Google search, which led her to Dr. Jennifer Doudna.10

Doudna and Max Planck Institute’s Emmanuelle Charpentier initially collaborated to understand how and if bacteria implement interference systems analogous to human biology. Eventually this collaboration led to the development of CRISPR-Cas9 gene-editing tools. Both women were awarded the Nobel Prize in Chemistry in 2020.11

Breaking Down the Breakthrough

To sum it up, the struggle of primordial organisms to the Nobel Prize, the journey of CRISPR technology is woven through every facet of scientific pursuit. So, whatever your subject is, wherever you’re studying it, you possess the potential to be the gateway of understanding for a novel arena of discovery.

To learn more about the Thermo Fisher products and instruments that can equip you for wherever your gene editing projects will take you, visit our Genome Editing page.

In addition, CRISPR technology is presenting profound and novel possibilities in the research and healthcare industries. Thermo Fisher’s CRISPR products can help you stay on the forefront of that innovation.

To learn more about the history of CRISPR development, check out parts 1 and 2 of our video series on the history of CRISPR, written and narrated by University of Oxford’s Yasmin Dickinson.

Want to read more stories like this? Subscribe to Connect to Science, your portal for life science news. 

 

For Research Use Only. Not for use in diagnostic procedures.

References

  1. Fortier L, Sekulovic O. Importance of prophages to evolution and virulence of bacterial pathogens. Virulence. 2013; 4(5):354–365. doi:10.4161/viru.24498
  2. 2 Watson B, Steens J, et. al. Coevolution between bacterial CRISPR-Cas systems and their bacteriophages.Cell Host & Microbe. 2021; 29(5):715–725. doi:10.1016/j.chom.2021.03.018
  3. Kysela DT, Turner PE. Optimal bacteriophage mutation rates for phage therapy.Journal of Theoretical Biology. 2007; 249(3):411-421. doi:10.1016/j.jtbi.2007.08.007
  4. Ishino Y, Krupovic M, Forterre P. History of CRISPR-Cas from Encounter with Mysterious Repeated Sequence to Genome Editing Technology. Journal of Bacteriology. 2018; 200(7). doi:10.1128/JB.00580-17
  5. Mojica F, Rodriguez-Valera F. The discovery of CRISPR in archaea and bacteria. The FEBS Journal. 2016. doi:10.1111/febs.13766
  6. Rodriguez Fernandez C. Francis Mojica, the Spanish Scientist Who Discovered CRISPR. LABIOTECH.eu. Published April 8, 2019. https://www.labiotech.eu/interview/francis-mojica-crispr-interview/
  7. CRISPR Timeline. MIT Broad Institute website: https://www.broadinstitute.org/what-broad/areas-focus/project-spotlight/crispr-timeline. Accessed July 28, 2022.
  8. Zhao J, Guo H. RNA silencing: from discovery and elucidation to application and perspectives. Journal of Integrative Plant Biology. 2021; 64(2):476-498. doi:10.1111/jipb.13213
  9. Fire A, Xu S, et. al. Potent and specific genetic interference by double-stranded RNA in C. elegans. Nature. 1998; 391:806-811. doi: 10.1038%2F35888

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