Stories about: CRISPR-Cas9

New angles for blocking Shiga and ricin toxins, and new light on an iconic biological process

Shiga toxin producing E. coli
Shiga-toxin-producing E. coli (IMAGE: JANICE HANEY CARR / USCDC)

Min Dong, PhD, and his lab are world experts in toxins and how to combat them. They’ve figured out how Clostridium difficile’s most potent toxin gets into cells and zeroed in on the first new botulinum toxin identified since 1969. Now, they’ve set their sights on Shiga and ricin toxins, and not only identified new potential lines of defense, but also shed new light on a fundamental part of cell biology: glycosylation.

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Patients’ individual genomes may affect efficacy, safety of gene editing

gene editing - truck delivering code
Subtle genetic variants in or near the gene editing target site could cause reagents to miss an address or arrive at the wrong one, researchers say.

Gene editing has begun to be tested in clinical trials, using CRISPR-Cas9, zinc finger nucleases (ZFN) and other technologies to directly edit DNA inside people’s cells. Multiple trials are in the recruiting or planning stages. But a study in PNAS this week raises a note of caution, finding that person-to-person genetic differences may undercut the efficacy of the gene editing process or, in more rare cases, cause a potentially dangerous “off target” effect.

The study adds to evidence that gene editing may need to be adapted to each patient’s genome, to ensure there aren’t variants in DNA sequence in or near the target gene that would throw off the technology.

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A “CRISPR” view of Sturge-Weber syndrome is coming into focus

Colorized laboratory image showing tissue model containing the Sturge-Weber syndrome genetic mutation
Living blood vessels inside a microfluidic chip containing the genetic mutation (green) responsible for Sturge-Weber syndrome (Credit: Bischoff lab)

Three-dimensional modeling and CRISPR-Cas9 gene editing technology are giving scientists a new view into Sturge-Weber syndrome, a rare congenital disorder that causes small blood vessels, called capillaries, to be malformed. These capillary malformations can cause port wine birthmarks on the face and neck, and in some cases, abnormal vasculature in the brain that can spark seizures.

Last year, a Boston Children’s Hospital research team — led by Joyce Bischoff, PhD, of the Vascular Biology Programdiscovered that the genetic mutation responsible for Sturge-Weber syndrome dwells in endothelial cells lining the affected capillaries in the brain. The team had previously found the same mutation present in the endothelial cells of skin capillaries of patients’ port wine birthmarks.

Together, their studies suggest that mutated endothelial cells could be causing surrounding cells to behave abnormally.

To explore this emerging hypothesis, Bischoff’s team is seeking lifelike ways of mimicking these hallmark capillary malformations in the laboratory.

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