Genomic complexity in non-Hodgkin’s Diffuse Large B-cell Lymphoma (DLBCL) leads to a
treatment failure in ~40% of patients. Activation-Induced Cytosine Deaminase (AID), one of
the enzymes involved in generating antibody diversity via class switching recombination
(CSR) and somatic hypermutation (SHM) of immunoglobulin (Ig) genes in activated B-cells is
one mechanism for the introduction of genomic lesions. In previous studies, AID was shown
to preferentially bind to super-enhancer (SE) regions within the genome, but 26% of AID
targets were not within the SE regions. The mechanism by which AID interacts with SE
elements and its off-target interactions still remains a mystery. Recent evidence suggests
that AID may cause genomic lesions in DLBCL via interaction with oncogenes such as MYC
and BCL2 resulting in mutations and translocations. Sequences within the MYC promoter
contain the four-nucleotide AID target sequence (WRCY) and highly G-rich sequences
known to form G-quadruplex DNA secondary structures. We hypothesize that key DNA
secondary structures act as recruiting elements for aberrant AID activity at promoters and
SEs of key genes involved in the development of DLBCL. Here, we first sought to determine
whether known AID DNA targets have the potential to form G-quadruplex DNA secondary
structures. The data collected from activated mouse B-cells showed 90% of the AID targets
contained sequences that could potentially form G-quadruplexes and the data collected
from the human Ramos cell line showed 100% of the sequences had the potential to form
G-quadruplexes. To further study our hypothesis we used the techniques circular dichroism
(CD) and the electrophoresis motility shift assay (EMSA) to explore the potential interaction
between AID and the BCL2 and MYC G-quadruplexes. We observed no significant interactions between AID and these two G-quadruplexes, however further experimentation with different conditions and molecular techniques may show interaction. Additional studies will not only provide key insight into the genomic instability within DLBCL, but will also provide a potential mechanism by which AID is recruited to its DNA targets.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/626339 |
| Date | January 2017 |
| Creators | Kalarn, Salil, Kalarn, Salil |
| Contributors | Kendrick, Samantha, Hurley, Laurence, Kendrick, Samantha, Hurley, Laurence, Krieg, Paul |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Electronic Thesis |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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