Department Chair

Dr. I. Martha Skerrett

Date of Award

11-2026

Access Control

Open Access

Degree Name

Master of Arts (MA)

Department

Biology

Advisor

Xiang-Dong “David” Zhang

Department Home page

https://biology.buffalostate.edu/

First Reader

Dr. Xiang-Dong “David” Zhang

Second Reader

Dr. Sandra Borbor-Sawyer

Third Reader

Dr. I. Martha Skerrett

Abstract

Global inhibition of SUMOylation increases chromosomal instability and nuclear abnormalities, including chromatin bridges, micronuclei, nuclear buds, and binuclei. However, the underlying mechanisms remain unclear. In this study, we hypothesized that SUMOylation of BRCA1 is pivotal for DNA double-strand break (DSB) repair and genome stability. My immunofluorescence microscopy revealed an increase in co-localization of BRCA1 and SUMO-2/3 at DSB foci in COS-7 cells after hydroxyurea treatment, suggesting that SUMOylation may play an important role in BRCA1 recruitment to DNA double-strand breaks. Using multiple bioinformatic tools, including UniProt, AlphaFold-2, PDB Viewer, GPS-SUMO 2.0, and DeepSUMO, I found that the BRCA1 RING and IDT domains are critical for BRCA1 interactions with BARD1, Ubc9, and one of the three SUMO isoforms (SUMO-1, SUMO-2, and SUMO-3). Furthermore, multiple bioinformatic analyses suggested the lysine 119 (K119) representing a key SUMOylation site and the 175–185 amino acid region containing a potential SUMO-interacting motif (SIM). To investigate the functional significance of BRCA1 SUMOylation, the tetracycline-inducible DNA constructs encoding BRCA1 wild-type or SUMOylation-deficient (K119R) mutant were generated by subcloning the DNA fragments encoding EGFP-tagged and 3×Flag-tagged BRCA1 into the pTetOne vector, respectively, and the EGFP-tagged and 3×Flag-tagged BRCA1 expressions in 293T cells were validated by Western blot. These newly generated DNA constructs and my experimental results provide a critical foundation for future studies in Zhang Lab to directly test the hypothesis that SUMOylation of BRCA1 plays a crucial role in repairing DSBs and preventing genome instability.

Download

Share

COinS