Identification of Aptamer for Human Telomeric Repeat Binding
Factor (TRF1) for the Control of Telomerase Activity
Helen Jung
3 September 2013
With
the rise of nuclear and linear DNA, eukaryotes had to overcome the imperfect
DNA replicating mechanism that arises from DNA polymerases’ inability to start
their own sequence. The advance of telomeres, non-coding DNA sequences at the
end of linear DNA, allows the preservation of genetic information in coding
sequences of DNA. These telomeres shorten in length as the specific DNA
molecule repeats replication, but excessive shortening of telomere can have
devastating consequences, such as HHS to be further described below. In
response, yeast and mammals maintain their telomere within a certain size range
through telomerase activity (de Lange, 2005). The access to each telomeric end
is strictly controlled by a telomere nucleoprotein complex, and they guard
telomeres against indiscriminate elongation by telomerase or inappropriate
modification by DNA damage repair system. Especially, telomeric repeat binding
factor (TRF1), a protein within the telomere nucleoprotein complex, negatively
regulates telomere length; its over-expression causes telomere shortening while
its under-expression results telomere elongation. (Kishi, etal, 2001).
oyeraal-Hreidarsson
Syndrome (HHS) is an X-linked genetic disorder that shows abnormalities in
telomere length and its maintenance, including defects in RTEL1 (Le Guen, etal, 2013). This condition impedes
development and shows symptoms of bone marrow failure and immunodeficiency.
Currently, there is no effective treatment for this condition. The objective of
this study is to select an aptamer—an oligonucleotide of three-dimensional
orientation that is selected to bind to and inhibit a specific target
protein—using repetitive talon bead-based selection method. In a previous
study, the overexpression of the protein TRF1 has shown strong telomere
shortening and damage, whereas under-expression of the protein has shown
telomere elongation (Kishi, etal,
2001). Thus, development of an aptamer against TRF1 can provide an outlook for
forced TRF1 inactivation. TRF1 inhibition results promoted telomeric repair
activities and offers potential aptamer therapeutics to alleviate the symptoms
of HHS.
This
study specifically aims to identify aptamer against TRF1 protein target and to
develop realistic potential therapeutic purposes of this aptamer against HHS.
Currently, there is no effective way of identification or remedy for the
symptoms. Potential medical applications for HHS will further be investigated.
His-tagged
TRF1 protein (Catalog number: 13044-H07B) can
be purchased from Sino Biological Inc. (sinobiological.com; Phone: 86-400-890-9989). Fifty micrograms, or about 990.01
picomoles, of TRF1 protein cost $290. The molecular weight of the target is
50.5Da. Each round of selection will be performed with about 100 picomoles of
TRF1 protein and is expected to cost about $30. The selection is performed
using talon beads, which are known to and are used in different laboratory (Stovall,
2013) to select against polyhistidine-tagged targets. These beads are already
available in the lab with other necessary equipment without any additional
cost.
References:
Target Proposal:
Progress Report:
https://drive.google.com/file/d/0BwhvTPTt0GX-ZDVLYnQ4SkRKUG8/edit?usp=sharing
Second Progress Report
Figure 1. The role of TRF1 in telomerase activity regulation and facilitation during S phase of the cell cycle.
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