Homologous recombination suppresses transgenerational DNA end resection and chromosomal instability in fission yeast.

Chromosomal instability (CIN) drives cell-to-cell heterogeneity, and the development of genetic diseases, including cancer. Impaired homologous recombination (HR) has been implicated as a major driver of CIN, however, the underlying mechanism remains unclear. Using a fission yeast model system, we establish a common role for HR genes in suppressing DNA double-strand break (DSB)-induced CIN.

DNA Double-Strand Break Repair Assay.

DNA double-strand breaks (DSBs), arising during normal DNA metabolism or following exposure to mutagenic agents such as ionizing radiation can lead to chromosomal rearrangements and genome instability, and are potentially lethal if unrepaired. Therefore, understanding the mechanisms of DSB repair and misrepair, and identifying the factors involved in these processes is of biological as well as medical interest. Here we describe a DSB assay in that can be used to identify and quantify different repair, misrepair, and failed repair events resulting from a site-specific DSB within the context of a nonessential minichromosome, Ch This assay can be used to determine the contribution of most genes or genetic backgrounds to DSB repair and genome stability, and can also provide mechanistic insights into their function.

The spliceosome-associated protein Nrl1 suppresses homologous recombination-dependent R-loop formation in fission yeast.

The formation of RNA-DNA hybrids, referred to as R-loops, can promote genome instability and cancer development. Yet the mechanisms by which R-loops compromise genome instability are poorly understood. Here, we establish roles for the evolutionarily conserved Nrl1 protein in pre-mRNA splicing regulation, R-loop suppression and in maintaining genome stability.

A histone H3K36 chromatin switch coordinates DNA double-strand break repair pathway choice.

DNA double-strand break (DSB) repair is a highly regulated process performed predominantly by non-homologous end joining (NHEJ) or homologous recombination (HR) pathways. How these pathways are coordinated in the context of chromatin is unclear. Here we uncover a role for histone H3K36 modification in regulating DSB repair pathway choice in fission yeast.

The DNA damage checkpoint pathway promotes extensive resection and nucleotide synthesis to facilitate homologous recombination repair and genome stability in fission yeast.

DNA double-strand breaks (DSBs) can cause chromosomal rearrangements and extensive loss of heterozygosity (LOH), hallmarks of cancer cells. Yet, how such events are normally suppressed is unclear. Here we identify roles for the DNA damage checkpoint pathway in facilitating homologous recombination (HR) repair and suppressing extensive LOH and chromosomal rearrangements in response to a DSB.

Functional ESCRT machinery is required for constitutive recycling of claudin-1 and maintenance of polarity in vertebrate epithelial cells.

Genetic screens in Drosophila have identified regulators of endocytic trafficking as neoplastic tumor suppressor genes. For example, Drosophila endosomal sorting complex required for transport (ESCRT) mutants lose epithelial polarity and show increased cell proliferation, suggesting that ESCRT proteins could function as tumor suppressors. In this study, we show for the for the first time to our knowledge that ESCRT proteins are required to maintain polarity in mammalian epithelial cells.