Difference between revisions of "Part:BBa K782060"

Latest revision as of 23:11, 26 September 2012

Interferon alpha-2a

Introduction

Interferons are cytokines that play an important role in the early immune response, exibit antiproliferative effects on cells and have immunomodulatory and antiviral function (Thomas et al., 2007). Type I interferons (IFN-alpha and beta) mediate signaling through the IFNAR receptor, the STAT1 and STAT2 components of the JAK/STAT-signal transduction pathway and finally, the interferon stimulated response element (ISRE) promotor element. IFN-alpha has been used since 1980s in the treatment of chronic hepatitis and still represents an important part of the management of chronic hepatitis C infection. Initial studies used an IFN-alpha monotherapy, but current treatments are a combination therapy consisting of ribavirin and IFN-alpha (Feld and Hoofnagle, 2005). Side effects of the treatment are still very common, with half of the patients suffering from flu like symptoms and a third experiencing emotional problems. Anxiety, sleep disorders and irritability are frequently observered and can in some cases lead to severe behavioral or phsycological disorders. This can in turn leed to discontinuation of therapy. With our biological delivery system we aim to overcome some of the adverse effects of the IFN therapy and make the therapy more efficient and affordable. We deposited the IFN-alpha-2a coding sequence in a BioBrick vector, but tested it's function uder a constitutive promoter.

Read more on our Wiki page ([http://2012.igem.org/Team:Slovenia/ImplementationHepatitisC iGEM team Slovenia - Hepatitis C]).

Figure 1. Shematic representation of INF-alpha-2a construct.

• IFN-alpha-2a was obtained from Sino Biological Inc.

Characterization

We tested the biological activity of IFN-alpha-2a produced by HEK293T cells. We used a STAT1/STAT2-responsive luciferase construct that encodes the firefly luciferase reporter gene under the control of a minimal promoter and tandem repeats of the interferon stimulated response element (ISRE). We designed the experiment as a co-culture of HEK293T cells transfected with either the IFN-alpha-2a producing plasmid or an empty vector, and HEK293T cells transfected with the reporter vector and renilla luciferase transfection control. Additionally, we performed a co-transfection experiment, where HEK293T cells were transfected with both the reporter and the IFN-alpha-2a producing plasmids. As a positive control, we used the response of the same reporter to recombinant IFN-beta.

Figure 2. Expressed and secreted IFN-α induces expression of an ISRE-dependant reporter. A co-culture of HEK293T cells transfected with either the IFN-α producing plasmid under the control of constitutive promoter or an empty vector and HEK293T cells transfected with firefly luciferase reporter with ISRE was prepared. Additionally, HEK293T cells were cotransfected with both the reporter and the IFN-α producing or control plasmids. After 24 hours of incubation, a dual luciferase reporter assay was performed.

We also performed an enzyme-linked immunosorbent assay (ELISA) of the IFN-alpha-2a production from HEK293T cells. We measured that on average a single cell produced 4,6 *10^-9 μg of IFN-alpha per day.

Refrences

Feld, J.J. and Hoofnagle, H. (2005) Mechanism of action of interferon and ribavirin in treatment of hepatitis C. Nature 436, 967-72.

Thomas, C., Moraga, I., Levin, D., Krutzik, P.O., Podoplelova, Y., Trejo, A., Lee, C., Yarden, G., Vleck, S.E., Glenn, J.S., Nolan, G.P., Piehler, J., Schreiber, G., Garcia, K.C. (2011) Structural linkage between ligand discrimination and receptor activation by type I interferons. Cell. 146(4), 621–632.

Sequence and Features