SUPERBOY.pptx

BSB 3143

GENE TECHNOLOGY


KALAISELVI

MOHANRAJ


SB
09031

RUBINI

DEVI

SELVARAJOO


SB
09005

SUMITHALAKSMY

GUNASEGARAN

SB
09063

(MUSCLE HYPERTROPHY)

BOSTON

—

Somewhere in
Germany is a baby Superman,
born in Berlin with bulging arm
and leg muscles. Not yet
5 in
2004,
he can hold seven
-
pound
weights with arms extended,
something many adults cannot
do. He has muscles twice the size
of other kids his age and half their
body fat.

The Associated Press, 2011

According to a DNA test, the
boy has a
genetic mutation that boosts muscle
growth
. This genetic mutation is called the
myostatin

deficiency.


The boy’s condition is the result of
carrying 2 mutated copies of the
myostatin

gene. His mother has only 1 such
mutation.

The Associated Press, 2011

Main steps:


•
Identification and


characterization of gene

•
Cloning of gene

•
Choice of vector

•
Method of delivery

•
Expression of gene

The first step is to
identify the genetic defect
and to
clone a good copy
of the gene involved.


Gene Knockout (Knock out mouse)


•
Isolate embryonic stem cells that originated from male
brown mice with a normal MSTN gene (blue)


•
A copy containing a mutated (inactive) MSTN gene ,
and a drug resistance marker gene is combined.


•
Homologous recombination


-

Similar genes will swap.


-

The mutant MSTN gene plus drug resistance marker gene is
now incorporated into the genome and the normal version is
kicked out.


•
Add drug


-

Cells that haven’t incorporated the inactive MSTN gene don’t
have the drug resistant marker gene.


-
Adding the drug kills cells without the marker, leaves us with
a clean batch of cells that all have an inactive version of the
MSTN gene.


•
Grow

Chimeric

Mice


-

Transplant the stem cells that carry the inactive MSTN gene
into a white mouse embryo to create chimera.

-
Chimeras have patches of cells throughout their bodies that grew
from white mouse cells and patches that grew from brown stem
cells.



-
Some of the cells that have the inactive MSTN gene may develop
into reproductive cells.



-
Chimeras are easy to identify because they have both brown and
white patches of fur.



•

Mate Male Chimera


-

If a male chimera has some reproductive cells (sperm) that
originated from the brown stem cells, he will produce some brown
offspring when mated with a white female.

•

Test & Breed Brown Offspring


-
Half of the brown offspring will have copy of the inactive MSTN gene in all of their
cells
–

including their reproductive cells. These mice have one normal copy of the
MSTN gene and one inactive copy.


-
-

These mice can be identified by PCR and then bred with each other.


•

One fourth of the resulting offspring will have two copies of the knocked out or
inactive MSTN genes.



•

Adeno
-
associated virus (AAV)

is a small

virus

which


infects humans and some other primate species.


•
AAV is not currently known to cause

disease

and
consequently the virus causes a very mild

immune response.


•
Advantages:


-
AAV can infect both dividing and non
-
dividing cells and
may incorporate its

genome

into that of the host cell.



-
It is possible to target specific cell types by engineering
proteins on the virus surface to recognize special proteins
on the target cell’s surface.


-
95% of the time, it will integrate into a specific region on
chromosome 2, greatly reducing the chance that integration
will disrupt the function of


other genes in the cell.


-

Does not cause immune response.


Expression System:


Finally, the gene is expressed in the
patient.

•

Gene therapy is a powerful new technology that still requires several years
before it will make a noticeable impact on the treatment of disease.



•

Several major deficiencies include poor delivery system, both viral and non
viral and poor gene expression after genes are delivered.



•
However, in every field of medicine, the ability to give the patient therapeutic
genes offers extraordinary opportunities to treat, cure and ultimately prevent a
vast range of diseases that now plague mankind.