Article

Aneuploidy causes proteotoxic stress in yeast.

Koch Institute for Integrative Cancer Research, Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02138, USA
Genes & development (Impact Factor: 12.64). 12/2012; DOI: 10.1101/gad.207407.112
Source: PubMed

ABSTRACT Gains or losses of entire chromosomes lead to aneuploidy, a condition tolerated poorly in all eukaryotes analyzed to date. How aneuploidy affects organismal and cellular physiology is poorly understood. We found that aneuploid budding yeast cells are under proteotoxic stress. Aneuploid strains are prone to aggregation of endogenous proteins as well as of ectopically expressed hard-to-fold proteins such as those containing polyglutamine (polyQ) stretches. Protein aggregate formation in aneuploid yeast strains is likely due to limiting protein quality-control systems, since the proteasome and at least one chaperone family, Hsp90, are compromised in many aneuploid strains. The link between aneuploidy and the formation and persistence of protein aggregates could have important implications for diseases such as cancer and neurodegeneration.

1 Follower
 · 
150 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Many cancer-associated somatic copy number alterations (SCNAs) are known. Currently, one of the challenges is to identify the molecular downstream effects of these variants. Although several SCNAs are known to change gene expression levels, it is not clear whether each individual SCNA affects gene expression. We reanalyzed 77,840 expression profiles and observed a limited set of 'transcriptional components' that describe well-known biology, explain the vast majority of variation in gene expression and enable us to predict the biological function of genes. On correcting expression profiles for these components, we observed that the residual expression levels (in 'functional genomic mRNA' profiling) correlated strongly with copy number. DNA copy number correlated positively with expression levels for 99% of all abundantly expressed human genes, indicating global gene dosage sensitivity. By applying this method to 16,172 patient-derived tumor samples, we replicated many loci with aberrant copy numbers and identified recurrently disrupted genes in genomically unstable cancers.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Genomic aneuploidy is a common cause of human genetic disorders. Individuals with aneuploidy tend to develop malignancies. Recent studies correlated aneuploidy with early aging, senescence and organ dysfunction. This study investigated potential explanations for these increased risks by evaluating random aneuploidy and senescence rates in amniocytes from fetuses with aneuploidy. The rates of random aneuploidy in amniocytes from normal pregnancies were evaluated and compared to amniocytes from fetuses with trisomy 21, 18 and 47XXY using FISH technique with X+Y, 9 and 18 probes. Senescence was evaluated by calculating the percentage of amniocytes with fragmented nuclei: senescence associated heterochromatin foci (SAHF), using DAPI staining. Significantly increased rates of cells with aneuploidy were observed in trisomies 18 and 21, and 47,XXY (p<0.001) compared to the control group for the somatic and sex chromosomes. Increased rates of amniocytes with SAHFs were observed among the trisomy samples compared to the control group. Higher incidence of random aneuploidy and senescence were observed in amniocytes from fetuses with trisomy. These findings might explain the greater lifetime tendency to develop malignancies and diseases related to early aging in these individuals. Copyright © 2015. Published by Elsevier B.V.
    Gene 02/2015; DOI:10.1016/j.gene.2015.02.075 · 2.08 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Aneuploid genomes, characterized by unbalanced chromosome stoichiometry (karyotype), are associated with cancer malignancy and drug resistance of pathogenic fungi. The phenotypic diversity resulting from karyotypic diversity endows the cell population with superior adaptability. We show here, using a combination of experimental data and a general stochastic model, that the degree of phenotypic variation, thus evolvability, escalates with the degree of overall growth suppression. Such scaling likely explains the challenge of treating aneuploidy diseases with a single stress-inducing agent. Instead, we propose the design of an "evolutionary trap" (ET) targeting both karyotypic diversity and fitness. This strategy entails a selective condition "channeling" a karyotypically divergent population into one with a predominant and predictably drugable karyotypic feature. We provide a proof-of-principle case in budding yeast and demonstrate the potential efficacy of this strategy toward aneuploidy-based azole resistance in Candida albicans. By analyzing existing pharmacogenomics data, we propose the potential design of an ET against glioblastoma. Copyright © 2015 Elsevier Inc. All rights reserved.