Disruption of Dna Polymerase Zeta Promotes An Innate Immune Response

<p>DNA polymerase ζ (pol ζ) is a specialized polymerase that protects cells from the consequences of DNA damage and stress. Without pol ζ function mammalian cells and yeast are exquisitely sensitive to genotoxic stresses including ultraviolet irradiation and platinum compounds such as the chemotherapeutic agent cisplatin. This elevated sensitivity arises from the central role of pol ζ in lesion bypass. Pol ζ is also required to protect cells from endogenous genomic damage or stress. In primary mammalian cells, the function of pol ζ is required for genome protection and normal proliferation. Immortalized <em>Rev3l</em>knockout (KO) MEFs are under considerable constitutive genomic stress, as demonstrated by elevated levels of micronuclei formation. As the cellular consequences of this stress remain unexplored, genome-wide transcriptional changes were measured in <em>Rev3l </em>KO MEFs. The work in this thesis demonstrates that loss of pol ζ promotes activation of an innate immune response.</p> <p><em>Rev3l </em>knockout MEFs had over 1000 genes that were either upregulated or downregulated more than 4-fold. Importantly, this revealed that loss of <em>Rev3l</em>induced an increase in expression of known interferon-stimulated genes indicating that the innate immune system may be activated. Increased expression of selected interferon-stimulated genes was confirmed at the mRNA and protein levels in <em>Rev3l</em>KO MEFs.</p> <p>Recently DNA damage has been shown to activate the innate immune system as another level of the DNA damage response. Micronuclei and other forms of cytosolic DNA, that can arise from genomic stress, can activate the cytosolic DNA sensor cGAS which promotes an interferon response with its signaling partner, STING. Knockdown of cGAS and STING in <em>Rev3l </em>KO MEFs significantly reduced expression of interferon-stimulated genes indicating that loss of pol ζ promotes activation of the cGAS-STING pathway. In sum the work in this thesis demonstrates that cells with defective pol ζ are under a constitutive activation of the cGAS-STING pathway. Pol ζ is already being explored as a therapeutic target to sensitize tumors to chemotherapeutic agents, like cisplatin. This work suggests that targeting pol ζ may also engage the innate immune system which could widen the uses of targeting pol ζ in cancer treatment.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation (PhD)

Year dc:date.available

2020

Authors dc:creator

• Martin, Sara
• <p><a href="https://orcid.org/0000-0002-7661-272X">https://orcid.org/0000-0002-7661-272X</a></p>

Contributors dc:contributor

• Richard Wood
• Blaine Bartholomew
• Francesca Cole

• DNA damage
• genome instability
• DNA polymerase ζ
• cGAS
• STING
• Cell Biology
• Medicine and Health Sciences

Repository record dc:identifier

https://digitalcommons.library.tmc.edu/utgsbs_dissertations/1050

OAI identifier oai:identifier

oai:digitalcommons.library.tmc.edu:utgsbs_dissertations-2105