Today we will be discussing gene editing technology,
such as RNA interference and the CRIPR method.
These are my dogs, Garrett and Nugget. They
are both the breed, weimaraners. Nugget is
the classic grey coloring of the breed, while
Garrett has the “blue” coloring. Garrett
wants to compete in dog shows, but he is not
allowed to as the American Kennel Association
disqualifies the blue colored weimaraners
from representing the breed.
This makes Garrett sad, and he told me he
wishes there could be a way that he could
be the grey color, just like Nugget.
So, I did some research and found out that
there are 2 ways that we could “silence”
the blue gene in Garretts hair, through RNA
interference and the CRISPR method.
The first method that we could use to make
Garrett a grey colored Weimaraner is through
CRISPR, also known as Clustered Regularly
Interspaced Short Palindromic Repeats.
This method uses a single guide RNA and a
Cas9 nuclease. Together, they form a complex
and the sgRNA guides the protein complex to
a protein that has been targeted, also called
the target site which can be seen in green.
The sgRNA matches a specific DNA sequence
and it searches for the match.
When the complex gets to the targeted protein
sequence, Cas9 recognizes the PAM sequence,
which is a short DNA sequence that is adjacent
to the target sequence. Cas9 is able to cut
the targeted double stranded DNA and then
this gene can either stay “cut” and be
disabled, or the sgRNA can insert different
RNA, seen in orange to create a different
gene.
The other method we could use would be the
RNA interference method of gene editing. This
method is done through blocking or degrading
the translation of a gene’s mRNA transcript.
This method uses short RNA, denoted as siRNA,
and microRNA, denoted as miRNA. RNA interference
can use both of these types of RNA together,
or it can use either one of them separately.
siRNA are designed to target mRNA that is
complementary to itself, and join to a molecule
called RISC, which is an argonaute protein.
This complex leads to one strand of DNA being
removed and RISC is able to bind to the strand
and destroys the mRNA and leads to RNA degradation.
microRNA, also used in RNAi, can also bind
to RISC, the protein. This complex can be
guided through the microRNA to repress mRNAs,
which means that translation is inhibited,
and this certain gene cannot be expressed.
But after all of this information, Garret
is still wondering which method would be best
for him. I would recommend that Garrett uses
the RNA interference method, as it is easier
to design than CRISPR and it can be designed
to target any mRNA at any locus. Although
the CRISPR method would allow for a complete
knockout of the blue coloring gene that he
has and the RNAi method could allow for very
little expression, I think the RNAi method
would be best for Garrett as it can be done
on organisms that are alive and is not fatal.
