Inhibition of Beta-secretase Amyloid Cleaving Enzyme (BACE1) by Aptamers, having therapeutic possibilities for Alzheimer’s Disease.

Faraz Damghani

Abstract:

            Alzheimer’s Disease (AD) is a neurodegenerative disease (disrupts the neuron cell’s ability to correctly transmit electrical current) that normally occurs when the human brain becomes elderly. Over time, the disease destroys memory, thinking skills and the brain’s ability to communicate to the rest of the body. Currently, there is no ultimate cure for AD and no definitive explanation for the cause of AD. Nevertheless, strong scientific evidence suggests that the buildup of beta amyloid plaques in the brain serve as the cause of AD. Beta amyloid plaques consist of cleaved sections of Amyloid Precursor Protein (APP) which is normally located in the membrane of neuron cells [1]. 

Figure 1: BACE1 initiates the cleaving of APP. Gamma secretase cleaves the other section of APP leading to beta amyloid formation [3].

Enzymes BACE1 and gamma-secretase amyloid cleave APP and the sections that were cleaved, build up causing amyloid plaques. Since BACE1 initiates the cleavage/formation of beta amyloid plaques, it logically makes sense that an aptamer that prevents BACE1 from cleaving APP will prevent beta amyloid plaques from forming [2]. When beta amyloid plaques are not formed than the neuron cells are able to keep their roles, thus, possibly preventing AD and its symptoms to occur.

Initially BACE1 cleaves APP close to the membrane in the extracellular region and then gamma scretase cleaves APP in the transmembrane region (figure 1). The amyloid beta is left behind and plaques start to form [2].

Specific Aim #1: To identify an aptamer against BACE1 through the SELEX process. The process requires several rounds of selection which help to find an aptamer with high affinity. It makes sense to use filter selection because the protein is not biotinylated and has a high molecular weight.  Other researchers have been successful in binding RNA aptamers to BACE1.

Specific Aim #2: The development of an aptamer for BACE1 can inhibit BACE1’s cleaving function. When APP is not cleaved than beta amyloid plaques are also not formed. Since it’s assumed that beta amyloid plaques have a huge role in AD, an aptamer that prevents plaques from happening can have therapeutic possibilities.

BACE1 with no tag (catalogue # BA1-H5213 ) can be ordered from ACROBIOSYSTEMS USA  at $280 per 100 micrograms [5]. The molecular weight of the enzyme is 70 kDa.   ACROBIOSYSTEMS can be reached via telephone at 301-825-5518. 

References:

1.Rentmeister,A., Bill,A., Wahle,T. (2006) “RNA aptamers selectively modulated protein

       

     recruitment to the cytoplasmic domain of B-secretase BACE1 invitro.” RNA 9:

     1650-1660.

2. Arnold, Steve and Missailidis, Sotiris (2009). Development of aptamers that bind to

      BACE1. Alzheimer's & Dementia, 5(4 Sup.), P416-P416.

3. Lammich S, Kojro E, Postina R, Gilbert S, Pfeiffer R, Jasionowski M, Haass C,

     Fahrenholz F. (1999). Constitutive and regulated alpha-secretase cleavage of

     Alzheimer's amyloid precursor protein by a disintegrin metalloprotease.

4. Mattson, M. Nature. 422, 385-387 (2003)

5. http://www.acrobiosystems.com/P234-Human-BACE1-Protein-Native.html#.UFaXdY1lSSo

  

Link to full proposal:
https://www.dropbox.com/s/patwcrfnfgqosvh/Damghani_Faraz-Target%20proposal.docx
Link to progress report 1:
https://www.dropbox.com/s/xqwzswh01nqci04/Damghani_Faraz-Fall%202012%20progress%20report%201.docx
Link to progress report 2:
https://www.dropbox.com/s/f9zmi4gor53d01l/Damghani_Faraz-Fall%202012%20progress%20report%202.docx
Link to final manuscript:
https://www.dropbox.com/s/rt8boeu1cdsjqg2/Damghani_Faraz-Fall%202012%20final%20manuscript.docx