Positional analyses of BRCA1-dependent expression in Saccharomyces cerevisiae

Abstract

Mutations in BRCA1 account for a significant proportion of hereditary breast and ovarian cancers, but analysis of BRCA1 function is complicated by pleiotropic effects and binding partners (Pol II holoenzyme and transcription factors, chromatin remodelers, recombination complexes and E3 ligases). In vertebrate cells, efforts to elucidate BRCA1 transcriptional effects have focused on specific genes or restricted portions of the genome—limiting analyses of BRCA1 effects on adjoining DNA sequences and along chromosome lengths. Here, we use microarray analyses on the genetically tractable yeast cell system to elucidate BRCA1-dependent genome-wide positional effects on both gene induction and repression. Yeast responses may be of clinical relevance based on findings that BRCA1 severely diminishes yeast growth kinetics but that BRCA1 mutated at sites identified from breast tumors is no longer able to retard yeast cell growth kinetics. Our analysis suggests that BRCA1 acts through both transcription factors to upregulate specific loci and chromatin remodeling complexes to effect global changes in gene expression. BRCA1 also exhibits gene repression activities. Cluster-functional analysis reveals that these repressed factors are required for mitotic stability and provide a novel molecular explanation for the conditional lethality observed between BRCA1 and chromosome segregation genes.

Cohesins coordinate gene transcriptions of related function withinSaccharomyces cerevisiae

“…In contrast to this expected outcome, the results show that a full 20% of the identified genes (6 of 29) are immediately adjacent to one another. When we include in our analyses affected genes separated by a single loci via single gap analysis, 43 the incidence of co-regulated adjacent genes rises to 25% – with some instances in which three contiguous loci are affected by cohesin inactivation (Table 2). Strand bias does not account for this extension of deregulation.…”

“…More recent findings provide a conceptual link between cohesion and BRCA1 function: BRCA1 expression is conditionally lethal in cohesion genes and other factors central to chromosome segregation. 43,55,56 …”

The expanding role of yeast in cancer research and diagnosis: insights into the function of the oncosuppressors p53 and BRCA1/2

“…A genomewide screen to identify mutants that permit growth in the presence of BRCA1 established a connection between BRCA1 and transcription complexes stalled by DNA damage. Moreover, gene expression profiles in yeast expressing five different BRCA1 missense variants in comparison with wild‐type BRCA1 showed changes in genes involved in a variety of pathways including transcription elongation, DNA replication, and repair (Skibbens et al ., ; Di Cecco et al ., ). These effects are presumably mediated by the interactions of exogenously expressed BRCA1 with the yeast genome and interacting proteins.…”

Functional analyses of human DNA repair proteins important for aging and genomic stability using yeast genetics

“…BRCA1 affects gene expression both globally and at specific loci, which contribute to adverse effects on cell growth and genomic stability [98]. Characterization of gene expression profiles in yeast expressing five different BRCA1 missense variants in comparison with wild-type BRCA1 showed changes in genes involved in a variety of pathways including transcription elongation, DNA replication and repair [96].…”