Prolonged exposure to particulate chromate inhibits RAD51 nuclear import mediator proteins

Journal Article · Fri Sep 15 00:00:00 EDT 2017 · Toxicology and Applied Pharmacology

DOI:https://doi.org/10.1016/J.TAAP.2017.05.030· OSTI ID:22722925

Browning, Cynthia L., E-mail: [e-mail] ^[1]; Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME 04469 ^[2]; Wise, John Pierce, E-mail: [e-mail] ^[1]; Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME 04469 ^[2]

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1. Wise Laboratory of Environmental and Genetic Toxicology, Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40292 (United States)
2. (United States)

Particulate hexavalent chromium (Cr(VI)) is a human lung carcinogen and a human health concern. The induction of structural chromosome instability is considered to be a driving mechanism of Cr(VI)-induced carcinogenesis. Homologous recombination repair protects against Cr(VI)-induced chromosome damage, due to its highly accurate repair of Cr(VI)-induced DNA double strand breaks. However, recent studies demonstrate Cr(VI) inhibits homologous recombination repair through the misregulation of RAD51. RAD51 is an essential protein in HR repair that facilitates the search for a homologous sequence. Recent studies show prolonged Cr(VI) exposure prevents proper RAD51 subcellular localization, causing it to accumulate in the cytoplasm. Since nuclear import of RAD51 is crucial to its function, this study investigated the effect of Cr(VI) on the RAD51 nuclear import mediators, RAD51C and BRCA2. We show acute (24 h) Cr(VI) exposure induces the proper localization of RAD51C and BRCA2. In contrast, prolonged (120 h) exposure increased the cytoplasmic localization of both proteins, although RAD51C localization was more severely impaired. These results correlate temporally with the previously reported Cr(VI)-induced RAD51 cytoplasmic accumulation. In addition, we found Cr(VI) does not inhibit interaction between RAD51 and its nuclear import mediators. Altogether, our results suggest prolonged Cr(VI) exposure inhibits the nuclear import of RAD51C, and to a lesser extent, BRCA2, which results in the cytoplasmic accumulation of RAD51. Cr(VI)-induced inhibition of nuclear import may play a key role in its carcinogenic mechanism since the nuclear import of many tumor suppressor proteins and DNA repair proteins is crucial to their function. - Highlights: • RAD51C nuclear localization is reduced after prolonged Cr(VI) exposure. • Prolonged Cr(VI) inhibits nuclear localization of BRCA2 less severely than RAD51C. • RAD51C deficiency induces the cytoplasmic accumulation of RAD51. • Cr(VI) does not inhibit interactions between RAD51 and its nuclear import partners.

• OSTI ID: 22722925
• Journal Information: Toxicology and Applied Pharmacology, Vol. 331; Conference: 9. conference on recent advances in metal toxicity and carcinogenesis research, Lexington, KY (United States), 1 Oct 2016; Other Information: Copyright (c) 2017 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0041-008X
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
CHROMATES
CYTOPLASM
DNA REPAIR
GENE RECOMBINATION
IMPORTS
INHIBITION
PARTICULATES
PUBLIC HEALTH
STRAND BREAKS