Functional Conservation of Cis-Regulatory Elements of Heat-Shock Genes over Long Evolutionary Distances

Transcriptional control of gene regulation is an intricate process that requires precise orchestration of a number of molecular components. Studying its evolution can serve as a useful model for understanding how complex molecular machines evolve. One way to investigate evolution of transcriptional regulation is to test the functions of cis-elements from one species in a distant relative. Previous results suggested that few, if any, tissue-specific promoters from Drosophila are faithfully expressed in C. elegans. Here we show that, in contrast, promoters of fly and human heat-shock genes are upregulated in C. elegans upon exposure to heat. Inducibility under conditions of heat shock may represent a relatively simple “on-off” response, whereas complex expression patterns require integration of multiple signals. Our results suggest that simpler aspects of regulatory logic may be retained over longer periods of evolutionary time, while more complex ones may be diverging more rapidly

Signatures of Selection in Fusion Transcripts Resulting From Chromosomal Translocations in Human Cancer

BACKGROUND: The recurrence and non-random distribution of translocation breakpoints in human tumors are usually attributed to local sequence features present in the vicinity of the breakpoints. However, it has also been suggested that functional constraints might contribute to delimit the position of translocation breakpoints within the genes involved, but a quantitative analysis of such contribution has been lacking. METHODOLOGY: We have analyzed two well-known signatures of functional selection, such as reading-frame compatibility and non-random combinations of protein domains, on an extensive dataset of fusion proteins resulting from chromosomal translocations in cancer. CONCLUSIONS: Our data provide strong experimental support for the concept that the position of translocation breakpoints in the genome of cancer cells is determined, to a large extent, by the need to combine certain protein domains and to keep an intact reading frame in fusion transcripts. Additionally, the information that we have assembled affords a global view of the oncogenic mechanisms and domain architectures that are used by fusion proteins. This can be used to assess the functional impact of novel chromosomal translocations and to predict the position of breakpoints in the genes involved

Next-Generation Sequencing of Apoptotic DNA Breakpoints Reveals Association with Actively Transcribed Genes and Gene Translocations

DNA fragmentation is a well-recognized hallmark of apoptosis. However, the precise DNA sequences cleaved during apoptosis triggered by distinct mechanisms remain unclear. We used next-generation sequencing of DNA fragments generated in Actinomycin D-treated human HL-60 leukemic cells to generate a high-throughput, global map of apoptotic DNA breakpoints. These data highlighted that DNA breaks are non-random and show a significant association with active genes and open chromatin regions. We noted that transcription factor binding sites were also enriched within a fraction of the apoptotic breakpoints. Interestingly, extensive apoptotic cleavage was noted within genes that are frequently translocated in human cancers. We speculate that the non-random fragmentation of DNA during apoptosis may contribute to gene translocations and the development of human cancers

The disruption of proteostasis in neurodegenerative diseases

Cells count on surveillance systems to monitor and protect the cellular proteome which, besides being highly heterogeneous, is constantly being challenged by intrinsic and environmental factors. In this context, the proteostasis network (PN) is essential to achieve a stable and functional proteome. Disruption of the PN is associated with aging and can lead to and/or potentiate the occurrence of many neurodegenerative diseases (ND). This not only emphasizes the importance of the PN in health span and aging but also how its modulation can be a potential target for intervention and treatment of human diseases.info:eu-repo/semantics/publishedVersio

Synergy Between Glutathione Peroxidase-1 and Astrocytic Growth Factors Suppresses Free Radical Generation and Protects Dopaminergic Neurons against 6-Hydroxydopamine

The degeneration of dopaminergic neurons in the course of Parkinson disease is largely blamed on oxidative damage in the brain. This study examined the potency of glutathione peroxidase-1 (GPX-1) to protect dopaminergic neurons against toxicity induced by the parkinsonian neurotoxin 6-hydroxydopamine (6-OHDA). We generated pLV-GPX1, a recombinant lentivirus vector carrying the coding sequence for human GPX-1, into the SK-N-MC neuroblastoma cell line. The pLV-GPX1–infected neurons showed an over 3-fold increase in enzyme expression and a 2.6-fold increase in enzyme activity compared to the pLV-EGFP–infected control cells. In the pLV-GPX1–infected cells, we also detected significantly increased neuronal survival and resistance to 6-OHDA–mediated toxicity compared to our controls (75 ± 4% versus 51 ± 7%, p < 0.001). To maximize this protection, the neurons were treated with conditioned medium taken from growing primary astrocytes (astro-CM). We found the treated pLV-GPX1–infected neurons even more significantly resistant to 6-OHDA toxicity compared to their untreated counterparts (86 ± 5% versus 75 ± 4%, p < 0.001). Concomitant with increased neuroprotection, co-presence of overexpressed GPX-1 and astro-CM significantly increased glutathione (GSH) levels compared to when either of the two was present (p < 0.001). Further analysis showed nearly 2.7-fold reduction, in the presence of astro-CM, of hydrogen peroxide (H2O2) levels released from the pLV-GPX1–infected neurons compared to control groups (p < 0.001). Finally, regression analysis between H2O2 levels and cell viability showed that co-presence of GPX-1 and astro-CM reduced 33% of cell death rate (p < 0.05). These data highlight the antioxidant properties of GPX-1 in protecting dopaminergic neurons and further emphasize the capacity of astrocytes in pumping growth-inducing factors that may synergize with GPX-1 to accelerate neuroprotection