DNA-Encoded Movie Points Way to ‘Molecular Recorder’

Original vs. CRISPR stored images

Credit: Seth Shipman, Harvard Medical School, Boston

There’s a reason why our cells store all of their genetic information as DNA. This remarkable molecule is unsurpassed for storing lots of data in an exceedingly small space. In fact, some have speculated that, if encoded in DNA, all of the data ever generated by humans could fit in a room about the size of a two-car garage and, if that room happens to be climate controlled, the data would remain intact for hundreds of thousands of years! [1]

Scientists have already explored whether synthetic DNA molecules on a chip might prove useful for archiving vast amounts of digital information. Now, an NIH-funded team of researchers is taking DNA’s information storage capabilities in another intriguing direction. They’ve devised their own code to record information not on a DNA chip, but in the DNA of living cells. Already, the team has used bacterial cells to store the data needed to outline the shape of a human hand, as well the data necessary to reproduce five frames from a famous vintage film of a horse galloping (see above).

But the researchers’ ultimate goal isn’t to make drawings or movies. They envision one day using DNA as a type of “molecular recorder” that will continuously monitor events taking place within a cell, providing potentially unprecedented looks at how cells function in both health and disease.

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Find and Replace: DNA Editing Tool Shows Gene Therapy Promise

Neutrophil being edited with CRISPR/Cas9

Caption: This image represents an infection-fighting cell called a neutrophil. In this artist’s rendering,  the cell’s DNA is being “edited” to help restore its ability to fight bacterial invaders.
Credit: NIAID, NIH

For gene therapy research, the perennial challenge has been devising a reliable way to insert safely a working copy of a gene into relevant cells that can take over for a faulty one. But with the recent discovery of powerful gene editing tools, the landscape of opportunity is starting to change. Instead of threading the needle through the cell membrane with a bulky gene, researchers are starting to design ways to apply these tools in the nucleus—to edit out the disease-causing error in a gene and allow it to work correctly.

While the research is just getting under way, progress is already being made for a rare inherited immunodeficiency called chronic granulomatous disease (CGD). As published recently in Science Translational Medicine, a team of NIH researchers has shown with the help of the latest CRISPR/Cas9 gene-editing tools, they can correct a mutation in human blood-forming adult stem cells that triggers a common form of CGD. What’s more, they can do it without introducing any new and potentially disease-causing errors to the surrounding DNA sequence [1].

When those edited human cells were transplanted into mice, the cells correctly took up residence in the bone marrow and began producing fully functional white blood cells. The corrected cells persisted in the animal’s bone marrow and bloodstream for up to five months, providing proof of principle that this lifelong genetic condition and others like it could one day be cured without the risks and limitations of our current treatments.

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Creative Minds: Modeling Neurobiological Disorders in Stem Cells

Feng Zhang

Feng Zhang

Most neurological and psychiatric disorders are profoundly complex, involving a variety of environmental and genetic factors. Researchers around the world have worked with patients and their families to identify hundreds of possible genetic leads to learn what goes wrong in autism spectrum disorder, schizophrenia, and other conditions. The great challenge now is to begin examining this growing cache of information more systematically to understand the mechanism by which these gene variants contribute to disease risk—potentially providing important information that will someday lead to methods for diagnosis and treatment.

Meeting this profoundly difficult challenge will require a special set of laboratory tools. That’s where Feng Zhang comes into the picture. Zhang, a bioengineer at the Broad Institute of MIT and Harvard, Cambridge, MA, has made significant contributions to a number of groundbreaking research technologies over the past decade, including optogenetics (using light to control brain cells), and CRISPR/Cas9, which researchers now routinely use to edit genomes in the lab [1,2].

Zhang has received a 2015 NIH Director’s Transformative Research Award to develop new tools to study multiple gene variants that might be involved in a neurological or psychiatric disorder. Zhang draws his inspiration from nature, and the microscopic molecules that various organisms have developed through the millennia to survive. CRISPR/Cas9, for instance, is a naturally occurring bacterial defense system that Zhang and others have adapted into a gene-editing tool.

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Creative Minds: Can Salamanders Show Us How to Regrow Limbs?

Jessica Whited

Jessica Whited /Credit: LightChaser Photography

Jessica Whited enjoys spending time with her 6-year-old twin boys, reading them stories, and letting their imaginations roam. One thing Whited doesn’t need to feed their curiosity about, however, is salamanders—they hear about those from Mom almost every day. Whited already has about 1,000 rare axolotl salamanders in her lab at Harvard University and Brigham and Women’s Hospital, Cambridge, MA. But caring for the 9-inch amphibians, which originate from the lakes and canals underlying Mexico City, certainly isn’t child’s play. Axolotls are entirely aquatic–their name translates to “water monster”; they like to bite each other; and they take 9 months to reach adulthood.

Like many other species of salamander, the axolotl (Ambystoma mexicanum) possesses a remarkable, almost magical, ability to grow back lost or damaged limbs. Whited’s interest in this power of limb regeneration earned her a 2015 NIH Director’s New Innovator Award. Her goal is to discover how the limbs of these salamanders know exactly where they’ve been injured and start regrowing from precisely that point, while at the same time forging vital new nerve connections to the brain. Ultimately, she hopes her work will help develop strategies to explore the possibility of “awakening” this regenerative ability in humans with injured or severed limbs.

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Flipping a Genetic Switch on Obesity?

Illustration of a DNA switchWhen weight loss is the goal, the equation seems simple enough: consume fewer calories and burn more of them exercising. But for some people, losing and keeping off the weight is much more difficult for reasons that can include a genetic component. While there are rare genetic causes of extreme obesity, the strongest common genetic contributor discovered so far is a variant found in an intron of the FTO gene. Variations in this untranslated region of the gene have been tied to differences in body mass and a risk of obesity [1]. For the one in six people of European descent born with two copies of the risk variant, the consequence is carrying around an average of an extra 7 pounds [2].

Now, NIH-funded researchers reporting in The New England Journal of Medicine [3] have figured out how this gene influences body weight. The answer is not, as many had suspected, in regions of the brain that control appetite, but in the progenitor cells that produce white and beige fat. The researchers found that the risk variant is part of a larger genetic circuit that determines whether our bodies burn or store fat. This discovery may yield new approaches to intervene in obesity with treatments designed to change the way fat cells handle calories.

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