Project description:The central nervous system normally functions at O2 levels which would be regarded as hypoxic by most other tissues. However, most in vitro studies of neurons and astrocytes are conducted under hyperoxic conditions without consideration of O2-dependent cellular adaptation. We analyzed the reactivity of astrocytes to 1, 4 and 9% O2 tensions compared to the cell culture standard of 20% O2, to investigate their ability to sense and translate this O2 information to transcriptional activity. Variance of ambient O2 tension for rat astrocytes resulted in profound changes in ribosomal activity, cytoskeletal and energy-regulatory mechanisms and cytokine-related signaling. Clustering of transcriptional regulation patterns revealed four distinct response pattern groups that directionally pivoted around the 4% O2 tension, or demonstrated coherent ascending/decreasing gene expression patterns in response to diverse oxygen tensions. Immune response and cell cycle/cancer-related signaling pathway transcriptomic subsets were significantly activated with increasing hypoxia, whilst hemostatic and cardiovascular signaling mechanisms were attenuated with increasing hypoxia. Our data indicate that variant O2 tensions induce specific and physiologically-focused transcript regulation patterns that may underpin important physiological mechanisms that connect higher neurological activity to astrocytic function and ambient oxygen environments. These strongly defined patterns demonstrate a strong bias for physiological transcript programs to pivot around the 4% O2 tension, while uni-modal programs that do not, appear more related to pathological actions. The functional interaction of these transcriptional ‘programs’ may serve to regulate the dynamic vascular responsivity of the central nervous system during periods of stress or heightened activity.
Project description:The central nervous system normally functions at O2 levels which would be regarded as hypoxic by most other tissues. However, most in vitro studies of neurons and astrocytes are conducted under hyperoxic conditions without consideration of O2-dependent cellular adaptation. We analyzed the reactivity of astrocytes to 1, 4 and 9% O2 tensions compared to the cell culture standard of 20% O2, to investigate their ability to sense and translate this O2 information to transcriptional activity. Variance of ambient O2 tension for rat astrocytes resulted in profound changes in ribosomal activity, cytoskeletal and energy-regulatory mechanisms and cytokine-related signaling. Clustering of transcriptional regulation patterns revealed four distinct response pattern groups that directionally pivoted around the 4% O2 tension, or demonstrated coherent ascending/decreasing gene expression patterns in response to diverse oxygen tensions. Immune response and cell cycle/cancer-related signaling pathway transcriptomic subsets were significantly activated with increasing hypoxia, whilst hemostatic and cardiovascular signaling mechanisms were attenuated with increasing hypoxia. Our data indicate that variant O2 tensions induce specific and physiologically-focused transcript regulation patterns that may underpin important physiological mechanisms that connect higher neurological activity to astrocytic function and ambient oxygen environments. These strongly defined patterns demonstrate a strong bias for physiological transcript programs to pivot around the 4% O2 tension, while uni-modal programs that do not, appear more related to pathological actions. The functional interaction of these transcriptional ‘programs’ may serve to regulate the dynamic vascular responsivity of the central nervous system during periods of stress or heightened activity. Cerebral cortices were removed from 6-8-day-old Wistar rats, cortical astrocytes were isolated and these cells were maintained in a humidified incubator at 37°C (95% air; 5% CO2). This resulted in a culture of cortical astrocytes, as confirmed by visual inspection the following day and later by glial fibrillary acidic protein immunohistochemistry. Any cortical astrocyte culture that was not homogenous was disposed of and not used in this study. Culture medium was exchanged every 7 days and cells were grown in culture for up to 14 days. 24hr prior to experimentation cells were transferred to an hypoxic workstation equilibrated with either 1%, 4%, 9% or 21% O2 and 5% CO2, with the remaining percentage gas being N2. Once cortical astrocytes had reached approximately 90% confluence (75cm2 flask) they were subjected to hypoxia as above, washed with PBS, removed from the flask base with 0.05% trypsin-EDTA (Gibco) and then gently centrifuged (500xg). The cell pellet was re-suspended in PBS, centrifuged twice more to remove any traces of media, then triturated in 8-10 volumes of RNAlater (Applied Biosystems), frozen and stored at -80oC. Messenger RNA was amplified and labeled with biotin using the standard Illumina protocol (Illumina TotalPrep RNA Amplification Kit Ambion; Austin, TX, cat # IL1791), and hybridized to Illumina's Sentrix Rat Ref-12,v1 Expression BeadChips (Illumina, San Diego, CA). Three replicates from each treatment group (1%, 21%, 4%, and 9% O2) were hybridized and the data was extracted using the Illumina BeadStudio software(v3.4).
Project description:Nitrogen fixation is a highly energy-demanding process and highly regulated at multiple levels. The two major signals that regulate nitrogen fixation in most diazotrophs are oxygen and ammonia. In order to study the complex regulated mechanism and to highlight the complete nitrogen fixing system in genome level, here we present the transcriptional profiles of the nitrogen fixation genes of P.stutzeri A1501 in different growth conditions with a genome-wide DNA microarray. In this study, the three samples of "P.stutzeri A1501 treated with 0.1mM ammonia and 0.5% Oxygen tension","P.stutzeri A1501 treated with 0.1mM ammonia and 0.5% Oxygen tension-2" and "P.stutzeri A1501 treated with 0.1mM ammonia and 0.5% Oxygen tension-3" were three repeat experiments, while, the other three samples of "P.stutzeri A1501 treated with 20mM ammonia and 0.5% Oxygen tension-1", "P.stutzeri A1501 treated with 20mM ammonia and 0.5% Oxygen tension-2" and "P.stutzeri A1501 treated with 20mM ammonia and 0.5% Oxygen tension-3" were three repeat experiments. The gene expressions under these two growth phases were compared to investigate which genes' expression were effected by different ammonia concentrations. Keywords: nitrogen fixation, nitrogen repression
Project description:Atmospheric oxygen tension is increasingly recognized to be hyperoxic for the maintenance of in vitro cell cultures. Oxygen has broad implications on energy metabolism, cellular growth and many regulatory functions. Primary airway epithelial cells (AECs) differentiated at air-liquid interface (ALI) are the gold standard for preclinical assessment of cystic fibrosis transmembrane conductance regulatory (CFTR) modulator efficacy in CF. The fidelity of CF AECs cultured at atmospheric oxygen tension rather than at reduced oxygen tension which more closely reflect the in vivo environment has not been studied to date. This study examined the impact of ambient (21%) and low (2%) oxygen tension on the expansion and differentiation of nasal epithelial cells (hNECs) derived from 11 participants (8 with CF and 3 non-CF). hNECs expanded under normoxic and chronic hypoxic conditions demonstrated epithelial cobblestone morphology and similar proliferation rate. hNECs differentiated at hypoxia demonstrated poorer differentiation capacity (significantly thinner epithelium and lower TEER) and a shift from ciliated to secretory epithelial phenotype. Hypoxic differentiated hNECs had significantly shorter cilia length, slower beating frequency but had improved cilia coordination. CFTR functional response is altered in hypoxic differentiated hNECs. This study highlights the need to reconsider the oxygen tension used in CF primary cell cultures so as to preserve the characteristics and functional response of the cell models as we progress towards personalised medicine in CF.
Project description:Atmospheric oxygen tension is increasingly recognized to be hyperoxic for the maintenance of in vitro cell cultures. Oxygen has broad implications on energy metabolism, cellular growth and many regulatory functions. Primary airway epithelial cells (AECs) differentiated at air-liquid interface (ALI) are the gold standard for preclinical assessment of cystic fibrosis transmembrane conductance regulatory (CFTR) modulator efficacy in CF. The fidelity of CF AECs cultured at atmospheric oxygen tension rather than at reduced oxygen tension which more closely reflect the in vivo environment has not been studied to date. This study examined the impact of ambient (21%) and low (2%) oxygen tension on the expansion and differentiation of nasal epithelial cells (hNECs) derived from 11 participants (8 with CF and 3 non-CF). hNECs expanded under normoxic and chronic hypoxic conditions demonstrated epithelial cobblestone morphology and similar proliferation rate. hNECs differentiated at hypoxia demonstrated poorer differentiation capacity (significantly thinner epithelium and lower TEER) and a shift from ciliated to secretory epithelial phenotype. Hypoxic differentiated hNECs had significantly shorter cilia length, slower beating frequency but had improved cilia coordination. CFTR functional response is altered in hypoxic differentiated hNECs. This study highlights the need to reconsider the oxygen tension used in CF primary cell cultures so as to preserve the characteristics and functional response of the cell models as we progress towards personalised medicine in CF.
Project description:We performed high-time-resolution (HTR) transcriptome analyses of Pseudomonas aeruginosa PAO1 (PA) in a continuous cultivation system during the transition from high oxygen tension to low oxygen tension (HLOT) and the reversed transition from low to high oxygen tension (LHOT). From those genes responsive to both transient conditions, we identified 85 essential oxygen-availability responsive genes (EORGs), including the expected ones (arcDABC) encoding enzymes for arginine fermentation. We then predicted a highly accurate regulatory network for the EORGs of PA by integrating information from binding motif searching, literature and inverted HTR datasets. These results not only reveal stringent EORGs of PA and their transcription regulatory network, but also highlight that achieving a high accuracy of the inferred regulatory network might be only feasible for the apparently affected regulators under the given conditions but not for all the expressed regulators in a genome scale.
Project description:Oxygen is vital for the development and survival of mammals. In response to hypoxia, the brain initiates numerous adaptive responses at the organ level as well as at the molecular and cellular level, including the alteration of gene expression. Astrocytes play critical roles in the proper functioning of the brain, thus the manner in which astrocytes respond to hypoxia is likely important in determining the outcome of brain hypoxia. We used microarray gene expression profiling and data analysis algorithms to identify and analyze hypoxia-responsive genes in primary human astrocytes. We also compared the gene expression patterns in astrocytes with those in human HeLa cells and pulmonary artery endothelial cells (ECs). Remarkably, in astrocytes, 5 times as many genes were up-regulated as down-regulated, whereas in HeLa and pulmonary ECs, as many or more genes were down-regulated as up-regulated. More genes encoding hypoxia-inducible functions, such as glycolytic enzymes and angiogenic growth factors, were strongly induced in astrocytes compared to HeLa cells. The extent of induction was also greater than in HeLa cells. Further, gene ontology and computational algorithms revealed that many target genes of the EGF and insulin signaling pathways and the transcriptional regulators Myc, Jun and p53 were selectively altered by hypoxia in astrocytes and HeLa cells to a varying degree. These results provide a global view of the signaling and regulatory network mediating oxygen regulation in astrocytes, in comparison with that in HeLa cells. Experiment Overall Design: Gene expression profiles of three independent batches of astrocytes grown under normoxia were compared to gene expression profiles of three independent batches of astrocytes grown under 1% oxygen for 24 hours. Affymetrix U133 plus 2.0 microarrays were used.
Project description:To investigate the effect of oxygen tension on gene expression of nucleus pulposus cells, human primary nucleus pulposus cells were cultured under condition with low(1%) or normal(21%) concentration of oxygen, respectively. Then, all cells were harvested, and total RNA was extracted using trizol prior to RNA sequencing.
Project description:Oxygen is vital for the development and survival of mammals. In response to hypoxia, the brain initiates numerous adaptive responses at the organ level as well as at the molecular and cellular level, including the alteration of gene expression. Astrocytes play critical roles in the proper functioning of the brain, thus the manner in which astrocytes respond to hypoxia is likely important in determining the outcome of brain hypoxia. We used microarray gene expression profiling and data analysis algorithms to identify and analyze hypoxia-responsive genes in primary human astrocytes. We also compared the gene expression patterns in astrocytes with those in human HeLa cells and pulmonary artery endothelial cells (ECs). Remarkably, in astrocytes, 5 times as many genes were up-regulated as down-regulated, whereas in HeLa and pulmonary ECs, as many or more genes were down-regulated as up-regulated. More genes encoding hypoxia-inducible functions, such as glycolytic enzymes and angiogenic growth factors, were strongly induced in astrocytes compared to HeLa cells. The extent of induction was also greater than in HeLa cells. Further, gene ontology and computational algorithms revealed that many target genes of the EGF and insulin signaling pathways and the transcriptional regulators Myc, Jun and p53 were selectively altered by hypoxia in astrocytes and HeLa cells to a varying degree. These results provide a global view of the signaling and regulatory network mediating oxygen regulation in astrocytes, in comparison with that in HeLa cells. Experiment Overall Design: Gene expression profiles of three independent batches of HeLa cells grown under normoxia were compared to gene expression profiles of three independent batches of HeLa cells grown under 1% oxygen for 24 hours. Affymetrix U133 plus 2.0 microarrays were used.
Project description:Oxygen is vital for the development and survival of mammals. In response to hypoxia, the brain initiates numerous adaptive responses at the organ level as well as at the molecular and cellular levels, including the alteration of gene expression. Astrocytes play critical roles in the proper functioning of the brain; thus the manner in which astrocytes respond to hypoxia is likely important in determining the outcome of brain hypoxia. Here, we used microarray gene expression profiling and data-analysis algorithms to identify and analyze hypoxia-responsive genes in primary human astrocytes. We also compared gene expression patterns in astrocytes with those in human HeLa cells and pulmonary artery endothelial cells (ECs). Remarkably, in astrocytes, five times as many genes were induced as suppressed, whereas in HeLa and pulmonary ECs, as many as or more genes were suppressed than induced. More genes encoding hypoxia-inducible functions, such as glycolytic enzymes and angiogenic growth factors, were strongly induced in astrocytes compared with HeLa cells. Furthermore, gene ontology and computational algorithms revealed that many target genes of the EGF and insulin signaling pathways and the transcriptional regulators Myc, Jun, and p53 were selectively altered by hypoxia in astrocytes. Indeed, Western blot analysis confirmed that two major signal transducers mediating insulin and EGF action, Akt and MEK1/2, were activated by hypoxia in astrocytes. These results provide a global view of the signaling and regulatory network mediating oxygen regulation in human astrocytes.. This SuperSeries is composed of the following subset Series:; GSE3045: Astrocytic response to hypoxia; GSE3051: HeLa response to hypoxia Experiment