Investigating the role of TAB182 in the DNA damage response and replication stress pathways

Ryan, Ellis Louise (2016). Investigating the role of TAB182 in the DNA damage response and replication stress pathways. University of Birmingham. Ph.D.

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Abstract

It is well established that adenoviruses degrade components of the cellular DNA damage response, such as p53, DNA ligase IV and Mre11, in order to avoid detection from the host cell and thus, promote viral replication. Here we show TAB182, a protein of previously unknown function, is degraded following adenovirus serotype 5 and 12 infection. Similarly to other DNA damage proteins, together with the cellular Cullin 5 (during Ad5 infection) and Cullin 2 (during Ad12 infection). Interestingly, siRNA-mediated knockdown of TAB182 appears to be beneficial for adenovirus infection, as denoted by an increased expression of the adenoviral E1A protein and Cyclin E during adenovirus infection. Together with other studies, we confirm that TAB182 interacts with the large, multi-subunit CNOT complex. This complex has no defined function in mammalian cells, but is known to play a role in gene regulation in yeast. Interestingly, components of the CNOT complex are also degraded during adenovirus infection, whether adenovirus degrades TAB182 as well as CNOT for the same advantage is currently unknown.

Cells deficient in TAB182 are hypersensitive to agents that induce DNA replication stress and also exhibit abnormal replication dynamics following release from hydroxyurea-induced fork stalling. In particular, they display increased fork restart and elevated new origin firing following release from hydroxyurea treatment, suggesting that TAB182 prevents fork recovery and suppresses new origin firing following replication stress. Depletion of some components of the CNOT complex is able to rescue the phenotypes observed in TAB182 deficient cells, suggesting that TAB182 and the CNOT complex may act in concert at the replication fork. TAB182 deficient cells display less DNA gaps and breaks but increased levels of 53BP1 bodies in G1 and micronuclei, which are markers of genome instability, following replication stress. Whether TAB182 acts directly at the replication fork, or in conjunction with other proteins known to be involved in replication restart such as helicases, nucleases, or chromatin remodelling complexes, remains to be elucidated.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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