Nominated for the 'Best Therapeutic Project' award at the iGEM Giant Jamboree
The Cardiff Wales 2017 iGEM team had two main goals:
> To develop new tools in the Phytobrick standard that can be used for future studies using plant gene expression.
> To use the Nicotiana benthamiana leaf expression system to generate high levels of a protein that might be used as a therapeutic for Graves' disease,which is a major human autoimmune disease affecting thyroid function.
The Phytobrick standard uses the golden gate cloning system so we incorporated a set of previously-characterised plant promotors into this cloning system. Our promoters are designed to respond to several different hormone or environmental stimuli and are taken from the model plant Arabidopsis thaliana.
In order to test the function of these promotors we aimed to quantify their expression levels using luciferase transcriptional units and also use them to generate a thyroid stimulating hormone antagonist that might have the potential to treat Graves' disease.
Consequently, we have added several parts to the phytobrick registry. In addition we generated a Phytobrick level 1 construct that includes a luciferase gene that in future will provide a method that allows iGEM teams to simply evaluate whether their tobacco leaf transformations have been successful.
More details about the project can be found on our project description page.
We also developed a model that is designed to be flexible so that it can be used as a tool for future iGEM teams or even companies. This was designed so that it can estimate how many plants are needed to create a single dose of any plant-produced therapeutic with a given severity, depending on the plant expression system of choice. For our project, we used this model to estimate how many plants might be required to provide a single effective dose of our TSH antagonist. We demonstrated the flexibility by changing one variable extensively, so that it shows different expression vectors and systems.
We then integrated the research section of our human practices with the model, in order to estimate how many plants would be required using each expression platform to give a single effective dose to every sufferer of Graves' disease in the USA.
Graves' Disease
Grave’s Disease arises from the overproduction of the thyroid stimulating hormone (TSH).
Such overproduction leads to increased thyroxine levels, consequently resulting in hyperthyroidism. Our project will involve the expression of the human thyroid stimulating hormone antagonist (TSHantag) using the tobacco leaf expression system.
As of yet, there have been no examples using the tobacco system for expression of the TSHantag protein. Therefore, we will design and create unique transcriptional units (TUs) for expression of TSHantag in tobacco. These TUs will be introduced into tobacco using agrobacterium-mediated transformation.
At the end of the project our attempts to optimise the amount of TSH protein produced in tobacco are still ongoing. However we have already arranged a collaboration with thyroid researchers at University Hospital of Wales.They will test the efficacy of the plant-produced TSHantag in an in vitro diagnostic system.
