Scientists develop gene silencing DNA enzyme that can target a single
molecule
Breakthrough holds promise for disease treatments, precision medicine


Date:
May 8, 2023
Source:
University of California - Irvine
Summary:
Researchers have developed a DNA enzyme -- or DNAzyme -- that
can distinguish between two RNA strands inside a cell and cut
the disease- associated strand while leaving the healthy strand
intact. This breakthrough 'gene silencing' technology could
revolutionize the development of DNAzymes for treating cancer,
infectious diseases and neurological disorders.


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==========================================================================
FULL STORY ========================================================================== Researchers from the University of California, Irvine have developed a
DNA enzyme -- or DNAzyme -- that can distinguish between two RNA strands
inside a cell and cut the disease-associated strand while leaving the
healthy strand intact. This breakthrough "gene silencing" technology
could revolutionize the development of DNAzymes for treating cancer,
infectious diseases and neurological disorders.

DNAzymes are nucleic acid enzymes that cut other molecules. Through
chemistry, UCI's team developed the Dz 46 enzyme, which specifically
targets the allele- specific RNA mutation in the KRAS gene, the master regulator of cell growth and division, found in 25 percent of all human cancers. A description of how the team achieved this enzyme evolution
was recently published in the online journal Nature Communications.

"Generating DNAzymes that can effectively function in the natural
conditions of cell systems has been more challenging than expected,"
said corresponding author John Chaput, UCI professor of pharmaceutical sciences. "Our results suggest that chemical evolution could pave the
way for development of novel therapies for a wide range of diseases."
Gene silencing has been available for more than 20 years and some
FDA-approved drugs incorporate various versions of the technology, but
none can distinguish a single point mutation in an RNA strand. The benefit
of the Dz 46 enzyme is that it can identify and cut a specific gene
mutation, offering patients an innovative, precision medicine treatment.

The DNAzyme resembles the Greek letter omega and acts as a catalyst
by accelerating chemical reactions. The "arms" on the left and right
bind to the target region of the RNA. The loop binds to magnesium, and
folds and cuts the RNA at a very specific site. But generating DNAzymes
with robust multiple turnover activity under physiological conditions
required some ingenuity, because DNAzymes are normally very dependent
on concentrations of magnesium not found inside a human cell.

"We solved that problem by re-engineering the DNAzyme using chemistry to
reduce its dependency on magnesium and did so in such a way that we could maintain high catalytic turnover activity," Chaput said. "Ours is one of
the very first, if not the first, example of achieving that. The next
steps are to advance Dz 46 to a point that it's ready for pre-clinical
trials." Team members Kim Thien Nguyen, project scientist, and Turnee
N. Malik, postdoctoral scholar, both from the Department of Pharmaceutical Sciences, also participated in this study.

The researchers and UCI have filed provisional patent applications on
the chemical composition and cleavage preference of Dz 46. Chaput is a consultant for drug development company 1E Therapeutics, which supported
this work.

* RELATED_TOPICS
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o Telomere o Genetic_code o Chemotherapy o DNA o
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========================================================================== Story Source: Materials provided by
University_of_California_-_Irvine. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Kim Nguyen, Turnee N. Malik, John C. Chaput. Chemical evolution
of an
autonomous DNAzyme with allele-specific gene silencing
activity. Nature Communications, 2023; 14 (1) DOI:
10.1038/s41467-023-38100-9 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/05/230508190607.htm

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