Date of Award

Spring 2024

Degree Type



College of Pharmacy

Director of Thesis

Dr. Douglas L. Pittman

Second Reader

Dr. Lydia E. Matesic


Homologous recombination (HR) is a repair pathway for DNA double-stranded breaks. Mutations in HR genes contribute to genomic instability and increase the prevalence of cancer. Exploiting HR deficiency in tumor cells has led to improved synthetic lethality outcomes. RAD51 paralogue protein complexes are known to be involved with HR. Proteomic analysis of RAD51 paralogues reveals a connection to the nuclear paraspeckle. A paraspeckle is a little-known, specialized organelle found in the interchromatin space of the nucleus in mammalian cells. Its three central protein components include SFPQ, NONO, and PSPC1. RAD51D is an HR protein shown previously to interact with SFPQ and NONO. The interaction between PSPC1 and RAD51D, or other HR proteins, however, has yet to be investigated. Therefore, this project analyzes the interactions between PSPC1 and three HR proteins, RAD51C, RAD51D, and XRCC2, using the yeast-2-hybrid (Y2H) system. Interactions between PSPC1 and NONO, along with SFPQ, were confirmed in the Y2H system. The results indicate PSPC1 is interacting with RAD51C and potentially XRCC2. Surprisingly, the data indicate that PSPC1 interacts with itself, demonstrating potential PSPC1 homodimerization. In conclusion, the data support the physical interactions between the HR and paraspeckle pathways. Therefore, alterations in genetic expression due to mutations within both pathways may potentially be used as cancer biomarkers and to identify genes for targeted drug therapeutics. Future studies should incorporate allelic variations and alternative splice variants of these genes to continue deciphering their interactions and investigate additional DNA damage repair and response pathways.

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