Biomod/2015/OhioMOD

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Abstract

Protein aggregates are the basis for diseases including Alzheimer’s, Parkinson’s, and Macular Degeneration. [CC1] The ability to detect the protein precursors to these aggregates, often misfolded proteins, provides crucial early-stage diagnostics and monitoring to ultimately improve treatment outcomes. Furthermore, where most biosensing devices simply provide a readout of the presence of the target, we aim to build a device that induces a functional response that aids to clear the target protein or to treat the disease.

We hypothesize that aptamer-functionalized DNA origami will bind specific target proteins; undergo conformational changes; and subsequently form oligomeric complexes that elicit a functional response to clear the protein or recruit components to the site of disease. While initial goals are focused on proof of concept with a purely DNA-based system, we will achieve the long term goals through a novel approach of using cryptic binding sites initially buried in the inner part of the device and exposed after the protein-driven conformational change. Our functional response will either expose signaling molecules to drive trafficking or aggregate sensors into defined geometries (inspired by the natural pentamer formation of immunoglobulin M (IgM) that recruits and activates complement, a key component of immune function).

The DNA nanostructure is comprised of two plates connected by a DNA hinge referred to hereafter as “BUS” – Biosensing Unit Structure. Gel electrophoresis and transmission electron microscopy (TEM) confirmed well-folded BUS. The BUS units have complementary overhangs to form dimers and trimers, as confirmed by TEM.

Future proof of principle experiments will utilize vascular endothelial growth factor (VEGF) and its corresponding aptamer to demonstrate simultaneous protein sequestration and trimer assembly. The BUS may be employed to target amyloids in addition to VEGF to ultimately become a theranostic device for the treatment of Macular Degeneration, Alzheimer’s-, and Parkinson’s disease.

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