College of Medicine, California Northstate University, Elk Grove, CA, 95757, USA.
Columbia University, New York, NY, 10027, USA.
Curr Genet. 2023 Dec;69(4-6):301-308. doi: 10.1007/s00294-023-01278-y. Epub 2023 Nov 7.
BRCA2 is a tumor-suppressor gene that is normally expressed in the breast and ovarian tissue of mammals. The BRCA2 protein mediates the repair of double-strand breaks (DSBs) using homologous recombination, which is a conserved pathway in eukaryotes. Women who express missense mutations in the BRCA2 gene are predisposed to an elevated lifetime risk for both breast cancer and ovarian cancer. In the present study, the efficiency of human BRCA2 (hBRCA2) in DSB repair was investigated in the budding yeast Saccharomyces cerevisiae. While budding yeast does not possess a true BRCA2 homolog, they have a potential functional homolog known as Rad52, which is an essential repair protein involved in mediating homologous recombination using the same mechanism as BRCA2 in humans. Therefore, to examine the functional overlap between Rad52 in yeast and hBRCA2, we expressed the wild-type hBRCA2 gene in budding yeast with or without Rad52 and monitored ionizing radiation resistance and DSB repair efficiency. We found that the expression of hBRCA2 in rad52 mutants increases both radiation resistance and DSB repair frequency compared to cells not expressing BRCA2. Specifically, BRCA2 improved the protection against ionizing radiation by at least 1.93-fold and the repair frequency by 6.1-fold. In addition, our results show that homology length influences repair efficiency in rad52 mutant cells, which impacts BRCA2 mediated repair of DSBs. This study provides evidence that S. cerevisiae could be used to monitor BRCA2 function, which can help in understanding the genetic consequences of BRCA2 variants and how they may contribute to cancer progression.
BRCA2 是一种肿瘤抑制基因，通常在哺乳动物的乳腺和卵巢组织中表达。BRCA2 蛋白通过同源重组介导双链断裂（DSBs）的修复，这是真核生物中保守的途径。表达 BRCA2 基因突变的女性易患乳腺癌和卵巢癌的终生风险升高。在本研究中，在酿酒酵母（Saccharomyces cerevisiae）中研究了人 BRCA2（hBRCA2）在 DSB 修复中的效率。尽管酿酒酵母没有真正的 BRCA2 同源物，但它们具有一种潜在的功能同源物，称为 Rad52，它是一种必需的修复蛋白，通过与人类 BRCA2 相同的机制介导同源重组。因此，为了研究酵母中的 Rad52 与 hBRCA2 之间的功能重叠，我们在酿酒酵母中表达了野生型 hBRCA2 基因，同时表达或不表达 Rad52，并监测电离辐射抗性和 DSB 修复效率。我们发现，与不表达 BRCA2 的细胞相比，rad52 突变体中 hBRCA2 的表达增加了辐射抗性和 DSB 修复频率。具体而言，BRCA2 将对电离辐射的保护作用提高了至少 1.93 倍，并将修复频率提高了 6.1 倍。此外，我们的结果表明，同源性长度影响 rad52 突变细胞中的修复效率，这会影响 BRCA2 介导的 DSB 修复。这项研究提供了证据表明，酿酒酵母可用于监测 BRCA2 功能，这有助于理解 BRCA2 变体的遗传后果以及它们如何促进癌症进展。
