Rewriting the Genetic Code

By:Ishika Desai

Genetic Code

• DNA is made up of long sequences of letters that code for specific amino acids.

• Codons are made up of three of these nucleotides (ACTG)

• Most three letter combos code for amino acids, but some represent stop codons.

How does it work?

• System overwrites specific DNA sequences within the genome

• Uses Multiplex Automated Genome Engineering (MAGE) to site-specifically replace stop codons across E. Coli strains

• Uses Conjugative Assembly Genome Engineering (CAGE) to precisely control a naturally occurring process that bacteria use to exchange genetic material

Potential Advances

• Engineer bacteria that are resistant to several viruses

• Build proteins not found in nature

Bibliography

• Isaacs, Farren J., Harris H. Wang, and Peter A. Carr. "Precise Manipulation of Chromosomes in Vivo Enables Genome-Wide Codon Replacement." Science Magazine: Sign In. N.p., 15 July 2011. Web. 09 July 2013. <http://www.sciencemag.org/content/333/6040/348.full>.

• Trafton, Anne. "Scientists Unveil Tools for Rewriting the Codeof Life." MIT's News Office. N.p., 15 July 2011. Web. 09 July 2013. <http://web.mit.edu/newsoffice/2011/editing-genome-0715.html>.

MedulloBLASToma

By: Ishika Desai

Medulloblastoma

• Malignant brain tumor located in the cerebellum

• Makes up 20% of brain tumors in children• Cause of medulloblastoma is unknown• Can become cancerous if it is combined with

the expression of the catenin beta 1 gene

β-catenin Gene

• Officially known as CTNNB1 • Expression of β-catenin is associated with:

• Carcinoma• Lung Cancer• Medulloblastoma• Malignant breast tumors• Endometrial cancer• Ovarian cancer

shRNA is generated within the aerotolerant E. coli via RNA interference

E. coli binds to β-1 integrin receptors on the cancerous cells and invade them

shRNA segments bind to β-catenin mRNA transcripts to silence the expression of this gene

shRNA production within E. coli

Pol II

Pre-

miR

NA

shRNA-induced silencing complex

Drosha

shRN

A

lysteriolysin O

Exportin 5 Dicer enzyme

Leaves E. coli

DNA

shRNA

shRNA

≈≈≈INVASIN PRODUCTION

GENETICALLY ENGINEERED E. COLI

CANCEROUS CELL

CTNNB1 mRNA

• Methods currently used to treat cancerous medulloblastomas:

• Surgery• Radiation • Chemotherapy

• All of the methods listed above generally still result in a considerable amount of damage to healthy tissue

• Oncologists and researchers have been looking into cancer treatments that precisely distinguish between healthy and diseased cells

Expected ResultsshRNA from E. coli Expression of CTNNB1

0 1

1 0

A XInverter (NOT) Logic Gate

Expected Results

• After invading the cancerous cells, it is expected that the shRNA in the RISC will bind to the CTNNB1 mRNA transcripts and induce mRNA cleavage

• This will silence the CTNNB1 gene