Expression of cancer related BRCA1 missense variants decreases MMS-induced recombination in Saccharomyces cerevisiae without altering its nuclear localization

ABSTRACT

BRCA1 tumor suppressor gene is found mutated in familial breast and ovarian cancer. Most cancer related mutations were found located at the RING (Really Interesting New Gene) and at the BRCT (BRca1 C-Terminal) domain. However, 20 y after its identification, the biological role of BRCA1 and which domains are more relevant for tumor suppression are still being elucidated. We previously reported that expression of BRCA1 cancer related variants in the RING and BRCT domain increases spontaneous homologous recombination in yeast indicating that BRCA1 may interact with yeast DNA repair/recombination. To finally demonstrate whether BRCA1 interacts with yeast DNA repair, we exposed yeast cells expressing BRCA1wt, the cancer-related variants C-61G and M1775R to different doses of the alkylating agent methyl methane-sulfonate (MMS) and then evaluated the effect on survival and homologous recombination. Cells expressing BRCA1 cancer variants were more sensitive to MMS and less inducible to recombination as compared to cell expressing BRCA1wt. Moreover, BRCA1-C61G and -M1775R did not change their nuclear localization form as compared to the BRCA1wt or the neutral variant R1751Q indicating a difference in the DNA damage processing. We propose a model where BRCA1 cancer variants interact with the DNA double strand break repair pathways producing DNA recombination intermediates, that maybe less repairable and decrease MMS-induced recombination and survival. Again, this study strengthens the use of yeast as model system to characterize the mechanisms leading to cancer in humans carrying the BRCA1 missense variant.

KEYWORDS:

• BRCA1
• homologous recombination
• Methyl methanesulfonate
• nuclear localization
• Saccharomyces cerevisiae

This article is referred to by:

What can yeast tell us about breast cancer?

Disclosure of potential conflicts of interest

No potential conflicts of interest were disclosed.

Acknowledgments

The authors wish to thank Robert Schiestl, Craig Bennett, Gael Millot and Valèrie Doye for providing yeast strain and plasmids. The authors are grateful to Richard Cumming for critical review of the manuscript.

Funding

Italian Association for Cancer Grant IG 2013 n. 14477 This work was supported by a grant of the Italian Association for Cancer (AIRC, Grant IG 2013 n. 14477) to A.G.