NUSAP1 Binds ILF2 to Modulate R-Loop Accumulation and DNA Damage in Prostate Cancer

• Published in: International journal of molecular sciences Vol. 24; no. 7; p. 6258
• Main Authors: Chiu, Chun-Lung, Li, Caiyun G, Verschueren, Erik, Wen, Ru M, Zhang, Dalin, Gordon, Catherine A, Zhao, Hongjuan, Giaccia, Amato J, Brooks, James D
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 26.03.2023; MDPI
• Subjects: Adenocarcinoma; Antibodies; Binding proteins; Breast cancer; Camptothecin; Cancer; Cell cycle; Confocal microscopy; Deoxyribonucleic acid; Depletion; DHX9; DNA; DNA Damage; DNA repair; Gene expression; Genetic aspects; Health aspects; Humans; Hybrids; ILF2; Immunoprecipitation; Localization; Male; Malignancy; Mass spectrometry; Mass spectroscopy; Metastases; Metastasis; Microscopy; Microtubule-Associated Proteins - metabolism; Motility; Nuclear Factor 45 Protein - genetics; Nuclear Factor 45 Protein - metabolism; NUSAP1; Prostate cancer; Prostatic Neoplasms - genetics; Prostatic Neoplasms - pathology; Protein binding; Protein interaction; Protein-protein interactions; Proteins; Proteomics; R-loop; R-Loop Structures; R-loops; RNA; RNA-binding protein; Scientific equipment and supplies industry; Therapeutic targets; United States; Massachusetts; NUSAP1; prostate cancer; DHX9; R-loop; ILF2; DNA damage
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms24076258

Increased expression of NUSAP1 has been identified as a robust prognostic biomarker in prostate cancer and other malignancies. We have previously shown that NUSAP1 is positively regulated by E2F1 and promotes cancer invasion and metastasis. To further understand the biological function of NUSAP1, we used affinity purification and mass spectrometry proteomic analysis to identify NUSAP1 interactors. We identified 85 unique proteins in the NUSAP1 interactome, including ILF2, DHX9, and other RNA-binding proteins. Using proteomic approaches, we uncovered a function for NUSAP1 in maintaining R-loops and in DNA damage response through its interaction with ILF2. Co-immunoprecipitation and colocalization using confocal microscopy verified the interactions of NUSAP1 with ILF2 and DHX9, and RNA/DNA hybrids. We showed that the microtubule and charged helical domains of NUSAP1 were necessary for the protein-protein interactions. Depletion of ILF2 alone further increased camptothecin-induced R-loop accumulation and DNA damage, and NUSAP1 depletion abolished this effect. In human prostate adenocarcinoma, and mRNA expression levels are positively correlated, elevated, and associated with poor clinical outcomes. Our study identifies a novel role for NUSAP1 in regulating R-loop formation and accumulation in response to DNA damage through its interactions with ILF2 and hence provides a potential therapeutic target.