Genotoxic stress in constitutive trisomies induces autophagy and the innate immune response via the cGAS-STING pathway.

Gain of even a single chromosome leads to changes in human cell physiology and uniform perturbations of specific cellular processes, including downregulation of DNA replication pathway, upregulation of autophagy and lysosomal degradation, and constitutive activation of the type I interferon response. Little is known about the molecular mechanisms underlying these changes. We show that the constitutive nuclear localization of TFEB, a transcription factor that activates the expression of autophagy and lysosomal genes, is characteristic of human trisomic cells.

Kinetic Analysis of Protein Stability Reveals Age-Dependent Degradation.

Do young and old protein molecules have the same probability to be degraded? We addressed this question using metabolic pulse-chase labeling and quantitative mass spectrometry to obtain degradation profiles for thousands of proteins. We find that >10% of proteins are degraded non-exponentially. Specifically, proteins are less stable in the first few hours of their life and stabilize with age.

The presence of extra chromosomes leads to genomic instability.

Aneuploidy is a hallmark of cancer and underlies genetic disorders characterized by severe developmental defects, yet the molecular mechanisms explaining its effects on cellular physiology remain elusive. Here we show, using a series of human cells with defined aneuploid karyotypes, that gain of a single chromosome increases genomic instability. Next-generation sequencing and SNP-array analysis reveal accumulation of chromosomal rearrangements in aneuploids, with break point junction patterns suggestive of replication defects.

Aneuploidy and proteotoxic stress in cancer.

Although nearly ubiquitous in cancer, aneuploidy exerts detrimental effects on human cells. We recently demonstrated that aneuploid human cells exhibit impaired heat shock factor protein 1 (HSF1) and HSP90 function, suggesting a functional link between two recurring features of cancer cells: aneuploidy and proteotoxic stress. Further, our findings implicate HSF1 as a key factor in mitigating the effects of aneuploidy.

Causes and consequences of protein folding stress in aneuploid cells.

Imbalanced chromosomal content, or aneuploidy, strongly affects the physiology of eukaryotic cells. The consequences of these effects are frequently detrimental, in particular in Metazoans. In humans, aneuploidy has been causatively linked to pathological conditions such as spontaneous abortions, trisomy syndromes and cancer.

HSF1 deficiency and impaired HSP90-dependent protein folding are hallmarks of aneuploid human cells.

Aneuploidy is a hallmark of cancer and is associated with malignancy and poor prognosis. Recent studies have revealed that aneuploidy inhibits proliferation, causes distinct alterations in the transcriptome and proteome and disturbs cellular proteostasis. However, the molecular mechanisms underlying the changes in gene expression and the impairment of proteostasis are not understood.

Dynamic karyotype, dynamic proteome: buffering the effects of aneuploidy.

Despite its ubiquity in cancer, link with other pathologies, and role in promoting adaptive evolution, the effects of aneuploidy or imbalanced chromosomal content on cellular physiology have remained incompletely characterized. Significantly, it appears that the detrimental as well as beneficial effects of aneuploidy are due to the altered gene expression elicited by the aneuploid state. In this review we examine the correlation between chromosome copy number changes and gene expression in aneuploid cells.

The eIF2α kinases: their structures and functions.

Cell signaling in response to an array of diverse stress stimuli converges on the phosphorylation of the α-subunit of eukaryotic initiation factor 2 (eIF2). Phosphorylation of eIF2α on serine 51 results in a severe decline in de novo protein synthesis and is an important strategy in the cell's armory against stressful insults including viral infection, the accumulation of misfolded proteins, and starvation. The phosphorylation of eIF2α is carried out by a family of four kinases, PERK (PKR-like ER kinase), PKR (protein kinase double-stranded RNA-dependent), GCN2 (general control non-derepressible-2), and HRI (heme-regulated inhibitor).

NOXA contributes to the sensitivity of PERK-deficient cells to ER stress.

PKR-like ER kinase (PERK) deficient mouse embryonic fibroblasts (MEFs) are hypersensitive to ER stress-induced apoptosis. However, the molecular determinants of increased sensitivity of PERK(-/-) MEFs are not clearly understood. Here we show that induction of several Unfolded Protein Response (UPR) target genes is attenuated in PERK(-/-) MEFs.

Mycobacterium avium subsp. Paratuberculosis and the expression of selected virulence and pathogenesis genes in response to 6°C, 65°c and ph 2.0.

The aim of this work was to study the expression of selected Mycobacterium avium subsp. paratuberculosis (MAP) genes connected with MAP virulence, adhesion and stress response. The temperature of 6°C and 65°C were chosen with regard to the food industry, storage conditions (refrigerator) and low-temperature pasteurization.