Nucleic Acid Aptamer Selection Against FasR for Inhibition of Nerve Cell Apoptosis

Owais Jamil

Fall 2012
September 4, 2012

N50 RNA Pool, FasR/CD95

Nucleic Acid Aptamer Selection Against FasR for Inhibition of Nerve Cell Apoptosis

Abstract: 

Permanent damage to the nervous system can be caused by severe physical trauma to the peripheral nervous system. Following this trauma, one of the ways loss of function occurs is secondary damage to the central nervous system, which occurs in the form of neuron death. If this can be prevented, victims will be able to retain motor and cognitive ability (2).

The Fas Receptor (FasR, also known as CD95) is a member of the tumor necrosis factor protein family that found on the surface of somatic cells and functions in cell death. When the Fas ligand (FasL) binds to FasR, a death inducing signaling complex (DISC) is formed (1). This triggers a downstream signaling cascade ending with apoptosis. In nervous system peripherals that have experienced trauma, FasR and FasL have been shown to be present in high quantities (4).

Apoptosis is the process of programmed cell death triggered by various signals or inducing factors. In the event of a spinal cord injury, damage occurs at the cellular level as a result of apoptosis. In healthy nervous systems, apoptosis pathways are used to eliminate unused neuronal connections and eliminate damaged cells (3). However, in the case of severe trauma, cell death can become uncontrolled, eliminating not only damaged cells but also healthy cells (2). These damages are irreversible and can lead to severe loss of nervous system function, and even death.

Specific Aim:
In the nervous system, when FasL binds to FasR, the DISC begins the pathway within the cell to lead to its death. To prevent this, perform the SELEX method to select an RNA aptamer with a high binding affinity for FasR. This aptamer would serve as a means to inhibit the function of FasR in healthy neurons that surround damaged nervous tissue, in hopes of preventing increased damage to the irreparable nerve tissue.

Figure 1. By inhibiting the function of FasR in healthy neurons surrounding trauma, loss of function can be minimized.

FasR/CD95 can be purchased from BD Pharmingen (Catalog#554256) at the price of $255 for 500 micrograms. (http://www.bdbiosciences.com/ptProduct.jsp?prodId=10379&catyId=745875)

References:

1. Kim, J.W., Choi, E., O Joe, C. 2000 “Activation of death-inducing signaling complex (DISC) by pro-apoptotic C-terminal fragment of RIP” Oncogene (19). 4491-4499

2. Beattie, M.S. 2004 “Inflammation and apoptosis: linked therapeutic targets in spinal cord injury” Trends in Molecular Medicine (12). 580-583

3. Groene, H-J., Herr, I., Krammer, P.H., Martin-Villalba, A. 2006 “Control of neuronal brancing by the death receptor CD95 (Fas/Apo-1)” Cell Death and Differentiation (13). 31-40

4. Shohami, E., Trentz, O., Kossman, T., Morganti-Kossman, M.C. 2007 “Immunohistochemical characterization of Fas (CD95) and Fas Ligand (FasL/CD95L) expression in injured brain: Relationship with neuronal cell death and inflammatory mediators” Histol Histopathol (22) 235-250