TRF2 is an essential telomeric protein involved in preventing the telomere ends
from being recognized as DNA breaks. I have shown that TRF2 does not appear to play
a major role in the UV -induced DNA damage response in IMR90, Cockayne syndrome or
XPC deficient cells. TRF2 binds telomeric DNA via its Myb domain and also contains an
N-terminal basic domain. Expression of TRF2MMM causes telomere fusions, whereas
TRF2^(ΔB) causes rapid deletion of telomeric DNA, as both phenotypes result in senescence.
These phenotypes are dependant upon recombination events. Thus, the basic domain of
TRF2 may be essential to suppress recombination events at telomeres. However, it is not
fully understood what amino acid residues in the basic domain of TRF2 are indispensable
to maintain its function. By creating mutations in the arginine residues in the basic
domain of TRF2, I have shown that the positive charge of the basic domain alone is not
sufficient to maintain its protective function. By expressing these TRF2 mutants in the
presence or absence of the Myb domain in HT1080 and BJ/hTERT cells, I have been able
to recapitulate the TRF2^(ΔB) and TRF2^(ΔBΔM) decreased proliferation and senescence
phenotypes. Furthermore, by analyzing anaphase and metaphase chromosomes and
performing Southern blotting, I have shed light on the molecular mechanisms responsible
for the deleterious phenotypes observed in the TRF2 mutants. Amino acid changes from
arginines to lysines introduced into the basic domain of TRF2 results in a significant
increase in telomere doublets. However, when these TRF2 mutants are expressed in the
absence of the Myb domain, a significant increase in telomere fusions events occur.
Collectively, my results indicate that more than one arginine residue in the basic domain is essential to maintain the protective function of TRF2, as these arginine residues may
act as substrates for protein arginine methyltransferases. / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/21674 |
| Date | 09 1900 |
| Creators | Glenfield, Kimberly |
| Contributors | Zhu, Xu-Dong, Biology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
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