Project description:Gene expression analysis of HeLa cells exposed to hypoxia (1% Oxygen), treated with a PHD inhibitor (IOX2) or treated with a VHL inhibitor (VH032) for 16 hours
Project description:Unusually among fungi, Saccharomyces cerevisiae is able to grow in environments containing almost no oxygen. A major feature of its response to hypoxia is a transition in expression from aerobic to hypoxic genes, which often code for duplicated isoforms of the same protein. In aerobic conditions, expression of the hypoxic gene set is repressed by the HMG domain protein Rox1. Here, we examined the evolution of ROX1 and related genes in the subphylum Saccharomycotina and find that a substantial reorganization of hypoxic gene regulation occurred during yeast evolution. S. cerevisiae lost ROX2, an ancient paralog of ROX1, which is almost universally present in other yeast species. ROX2 is orthologous to Candida albicans RFG1, a regulator of filamentous growth. Many yeasts, such as Candida glabrata, lack ROX1 and contain only ROX2. Others such as Naumovozyma castellii retain both genes. Although the ancestral function of ROX2 is uncertain, we find that it is not a regulator of hypoxic genes except in C. glabrata where it has taken over this function from the absent ROX1. We also find that N. castellii has a greatly attenuated transcriptional response to hypoxia as compared to other species, but that the ergosterol pathway which is normally induced by hypoxia can be induced by cobalt chloride stress in N. castellii.
Project description:Hypoxia is a common feature in various solid tumors including melanoma. Cancer cells in hypoxic environments are resistant to both chemotherapy and radiation. Hypoxia is also associated with immune suppression. Identification of proteins and pathways that regulate survival of cancer cells in hypoxic environments can reveal potential vulnerabilities that can be exploited to improve efficacy of anti-cancer therapy. We carried out global proteome and phosphoproteome profiling in melanoma cell lines to identify proteins and pathways that are induced by hypoxia. Here, using Orbitrap Fusion Mass Spectrometer for analysis and employing TMT-based quantitation, we report >7,000 proteins and >10,000 phosphosites. As expected, several proteins that are known targets of hypoxia inducible factors (HIFs) were found to be overexpressed in the hypoxic models. In addition, several metabolic enzymes showed altered expression revealing metabolic reprogramming in hypoxic conditions. Phosphoproteomic profiling revealed kinase mediated signaling pathways that are induced in hypoxic conditions. Our data provides a comprehensive view of proteomic and phosphoproteomic alterations in hypoxia and reveals potential mechanisms that regulate cell survival in hypoxic environments. These mechanisms can be targeted to improve therapeutic outcomes in cancer treatment. Further, we identify the 20S proteasome as a putative therapeutic target in melanoma.
Project description:Analysis of the transcriptome of the wild-type strain BY4741 and its isogenic derivative ixr1 null, grown in aerobic, hypoxic conditions and after a hypoxic shift
Project description:Aspergillus fumigatus is an opportunistic, airborne pathogen causing invasive aspergillosis in immunocompromised patients. During the infection process A. fumigatus is challenged by hypoxic microenvironments occurring in inflammatory, necrotic tissue. To gain further insights into the adaptation mechanism, A. fumigatus was cultivated in an oxygen-controlled chemostat under hypoxic and normoxic conditions. Transcriptome analysis revealed significant increases in transcripts associated with cell wall polysaccharide metabolism, amino acid and metal ion transport, nitrogen metabolism and glycolysis. A concomitant reduction in transcript levels was observed with cellular trafficking and G-protein coupled signaling. To learn more about the functional roles of hypoxia-induced transcripts we deleted A. fumigatus genes putatively involved in reactive nitrogen species detoxification (fhpA), NAD+ regeneration (frdA, osmA) nitrogen metabolism (niaD, niiA) and respiration (rcfB). We show that the NO-detoxifying flavohemoprotein fhpA is strongly induced by hypoxia independent of the nitrogen source, but is dispensable for hypoxic survival. By deleting the nitrate reductase gene niaD, the nitrite reductase gene niiA and the two fumarate reductases genes frdA and osmA, we found that alternative electron acceptors such as nitrate and fumarate do not have a significant impact on growth of A. fumigatus during hypoxia, but that functional mitochondrial respiratory chain complexes are essential under these conditions. Inhibition studies indicated that primarily complex III and IV play a crucial role in the hypoxic growth of A. fumigatus.
Project description:Notch signaling is an important regulator of stem cell differentiation. All canonical Notch signaling is transmitted through the DNA-binding protein CSL and hyperactivated Notch signaling is associated with tumor development; thus it may be anticipated that CSL deficiency should reduce tumor growth. In contrast, we report that genetic removal of CSL in breast tumor cells caused accelerated growth of xenografted tumors. Loss of CSL unleashed a hypoxic response during normoxic conditions, manifested by stabilization of the HIF1± protein and acquisition of a polyploid giant-cell, cancer stem cell-like, phenotype. At the transcriptome level, loss of CSL upregulated more than 1750 genes and less than 3% of those genes were part of the Notch transcriptional signature. Collectively, this suggests that CSL exerts functions beyond serving as the central node in the Notch signaling cascade and reveals a novel role for CSL in tumorigenesis and regulation of the cellular hypoxic response. CSL +/+ and CSL -/- MDA-MB-231 were subjected to Notch activation/inhibition and xenograft experiment. Total RNA were extracted from the samples and sent to NGS. Single Cell RNA-sequencing was also performed from cells isolated from xenograft tumors.