RNA Aptamer Selection Against Alpha-Synuclein As a Diagnostic Tool For Parkinson’s Disease

Alpha-synuclein (asynuc) is the primary component of Lewy bodies, which are known to be associated with Parkinson’s disease and other Lewy Body Diseases (Yokota et al. 2010). Aggregation and improper folding of asynuc can lead to the formation of Lewy bodies. This can cause damage to neurons and lead to cell death, which disrupts dopamine pathways in the brain.


Figure 1.) Lewy Body presentation in a human SN neuron. The Lewy Body is the blurry purple circle in the center of the photo. (from http://neuropathology.neoucom.edu/chapter9/images9/9-lb2.jpg)

Currently, the diagnosis of PD is based on the patient’s medical history and a neurological examination for deficient motor function. However, the accuracy of diagnosis is between 75 and 90% because many cases have uncommon presentations, especially in the early stages of the disease. The most accurate diagnosis of PD comes from finding Lewy bodies in the brain during autopsy.

Asynuc has been shown to accumulate in the cerebrospinal fluid and blood plasma of patients with PD (Tinsley et al.2010). An RNA aptamer with a high specificity and binding affinity for asynuc could be used to test the level of asynuc in a patient’s blood plasma. The aptamer would have a reporter sequence attached, which would indicate when the aptamer was bound to its target. An elevated level of asynuc would signify the presence of PD and could be a very useful diagnostic and research tool for the disease.

An antibody and DNA aptamer for asynuc have already been discovered. An RNA aptamer will expand PD research opportunities and might be more effective in reporting elevated levels of asynuc. RNA aptamers for asynuc will be selected for using the SELEX method. The specific aims of this project are to find an aptamer with high affinity and specificity for asynuc and to attach a reporter sequence that will indicate when asynuc is attached to the aptamer.

Figure 2. ) An RNA aptamer with a reporter sequence can be selected for that signifies the presence of its target, asynuc, when bound. This can be used to find elevated levels of asynuc in blood plasma.

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Scott, DA et al. (2010) "A pathologic cascade leading to synaptic dysfunction in alpha-synuclein-induced neurodegeneration." J Neurosci. 30(24):8083-95.

Tinsley,RB et al. (2010) "Sensitive and specific detection of alpha-synuclein in human plasma." J Neurosci. 88(12):2693-700.

Yokota, O et al. (2010) "Effect of topographical distribution of alpha-synuclein pathology on TDP-43 accumulation in Lewy body disease." Acta Neuropathol. [Epub ahead of print]

Tsukakoshi, K et al. (2010) "Screening of DNA aptamer which binds to alpha-synuclein." Biotechnol Lett. 32(5):643-8


Brad Hall said...

Lindsey, this abstract is well thought out and written. You clearly define the problem and provide a solution. Can you fix the picture? I can help if need be. You may include a picture of a Lewy body under the first paragraph. Below are some comments to enhance the readability.

1.) "Right now the main tools" isn't very scientific. Say, "Currently, PD is diagnosed by the patients medical history..."

2.) Is asynuc diagnostic? What are the numbers from the Tinsley paper? The success of aptamers as diagnostics hinges on what the baseline asynuc level suggests PD disease. Luckily, you may get away with an aptamer that doesn't bind tightly since you aren't measuring presence/absence but rather some threshold. If the threshold is high, its good for you!

3.) Please provide the references for both the antibody and DNA aptamer for asynuc.

4.) Reword "RNA aptamers will be selected for against..."

5.) Specific aim 1 is to find the aptamer. Specific aim 2 is to turn it into a reporter Unless, you choose to combine both into the same selection. Look at some of Manjula Rajendran's or Yingfu Li's work on this. But I would suggest doing them separate.

6.) Include your references.

Lindsay Becker said...

Ok, I've updated the abstract based on the changes you suggested. Please tell me how else I can improve it!

Brad Hall said...

Since we have this in lab, you can start immediately. This target does not have a tag on it, so I will need to verse you on filter selections along with Mayank and others. I find tagging proteins with biotin, although possible, laborious and sometimes problematic.

Either way, here is the protein information:

It is from EMD Chemicals, Cat # 575001. As of today, the price is $299 for 200ug and it is 14460 Da.

Lindsay Becker said...

I referenced the figures in the paragraphs. Drop box is awesome by the way.