CRISPR's Next Frontier: The Rise of a Game-Changing Precision Editor
In
the constantly progressing area of genome editing, accuracy and effectiveness
are the primary objectives. The most significant position among the CRISPR-Cas
systems occupies the Zinc-finger endonuclease Cas9 protein from Streptococcus
pyogenes more often called SpCas9. However, SpCas9 has its own limitations,
which caused researchers to feel the need for other options. There are some
candidates for base editors, among which the most prospective is the Cas9
protein from Francisella novicida (FnCas9). Despite FnCas9 showing high
specificity, the low efficiency has limited it from being widely used. To look
into more detail, the scientists have developed the paired advanced FnCas9
(enFnCas9), which opens up numerous opportunities in the therapeutic and diagnostic
fields.
FnCas9
is highly specific to target DNA sequences which has few chances of interacting
with other non-target sequences. However, its ability to focus and correct
targeted DNA location and editing within cells has in the past lacked the
needed efficiency. It was therefore necessary for the scientists to improve on
FnCas9’s efficiency while modelling it to be as selective as possible thereby
coming up with a tool that competes with SpCas9.
By
optimizing specific areas of the FnCas9 protein, several improved derivatives
have been created during the research. As with the previous examples, these
engineered proteins were shown to have a significantly higher efficiency while
not losing the selectivity. This advancement results in the simple fact that
the new enFnCas9 variants can be targeted within the human genome, roughly 3.5
times more than the original FnCas9. Another interesting aspect of these
enFnCas9 variants is their enhanced performance in diagnostics-related
procedures. They outcompete other forms of Cas9 in terms of identifying
pathogenic DNA signatures, including newer optimised forms of SpCas9. This
makes them especially useful in diagnostic tools that need to accurately pick
out infections or genetic problems among a large population.
The
application of enFnCas9 offers great prospects in the therapeutic field. These
variants showed striking improvement in on-target editing efficiency which
brought about lesser off-target effects in comparison to the rest. This pairing
is essential for creating effective and safe genetically therapeutic
applications. In addition, efficient base editing was achieved using the
enFnCas9 variants, which are important for the correction of Point mutation,
which was among the most common genetic errors that trigger several diseases.
An
interesting example of enFnCas9’s therapeutic benefit was exhibited in the cure
of a mutation that is linked to Leber congenital amaurosis 2 (LCA2), a severe
retinal disorder. An enFnCas9 adenine base editor was employed by the
researchers to correct the mutation in patient-derived cells wherein the proper
lifting of the embargo on the expression of the full length of the protein was
achieved. This highlights that enFnCas9 variants are not only capable of curing
genetic diseases but also repairing the normal function of cells.
Thus,
the development of enFnCas9 variants can be regarded as a progressive step in
the evolution of genome editing. These engineered proteins which demonstrate
high specificity along with improved efficiency create a new set of
opportunities in the genetic therapy and diagnostics paradigms. These results
demonstrate the efficacy of enFnCas9 in genetic medicine and hint at new
horizons for the treatments of genetic diseases.
Reference:
Acharya
S, Ansari AH, Kumar Das P, Hirano S, Aich M, Rauthan R, Mahato S, Maddileti S,
Sarkar S, Kumar M, Phutela R. PAM-flexible Engineered FnCas9 variants for
robust and ultra-precise genome editing and diagnostics. Nature Communications.
2024 Jun 28;15(1):5471. https://doi.org/10.1038/s41467-024-49233-w
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