Oncogene-induced senescence is an anti-proliferative stress response program that acts as a fail-safe mechanism to limit oncogenic transformation and is regulated by the retinoblastoma protein (RB) and p53 tumor suppressor pathways. We identify the atypical E2F family member E2F7 as the only E2F transcription factor potently upregulated during oncogene-induced senescence, a setting where it acts in response to p53 as a direct transcriptional target. Once induced, E2F7 binds and represses a series of E2F target genes and cooperates with RB to efficiently promote cell cycle arrest and limit oncogenic transformation. Disruption of RB triggers a further increase in E2F7, which induces a second cell cycle checkpoint that prevents unconstrained cell division despite aberrant DNA replication. Mechanistically, E2F7 compensates for the loss of RB in repressing mitotic E2F target genes.
The atypical E2F family member E2F7 couples the p53 and RB pathways during cellular senescence.
Cell line, Treatment
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Dissecting the unique role of the retinoblastoma tumor suppressor during cellular senescence.
Cell line
View SamplesThe action of RB as a tumor suppressor has been difficult to define, in part, due to the redundancy of the related proteins p107 and p130. By coupling advanced RNAi technology to suppress RB, p107 or p130 with a genome wide analysis of gene expression in growing, quiescent or ras-senescent cells, we identified a unique and specific activity of RB in repressing DNA replication as cells exit the cell cycle into senescence, a tumor suppressive program.
Dissecting the unique role of the retinoblastoma tumor suppressor during cellular senescence.
Cell line
View SamplesIt is well-established that neurons in the adult mammalian central nervous system are terminally differentiated and, if injured, will be unable to regenerate their connections. In contrast to mammals, zebrafish and other teleosts display a robust neuroregenerative response. Following optic nerve crush (ONX), retinal ganglion cells (RGC) regrow their axons to synapse with topographically correct targets in the optic tectum, such that vision is restored in ~21 days. What accounts for these differences between teleostean and mammalian responses to neural injury is not fully understood. A time course analysis of global gene expression patterns in the zebrafish eye after optic nerve crush can help to elucidate cellular and molecular mechanisms that contribute to a successful neuroregeneration.
Time Course Analysis of Gene Expression Patterns in Zebrafish Eye During Optic Nerve Regeneration.
Specimen part
View SamplesInfection is a major complication and cause of mortality and morbidity after acute stroke however the mechanisms are poorly understood. After experimental stroke the microarchitecture and cellular composition of the spleen are extensively disrupted resulting in deficits to immune function.
Experimental Stroke Differentially Affects Discrete Subpopulations of Splenic Macrophages.
Specimen part, Treatment
View SamplesAnalysis of gene expression before (P14), during (P28), and after (P60) the critical period for ocular dominance plasticity.
Gene expression patterns in visual cortex during the critical period: synaptic stabilization and reversal by visual deprivation.
No sample metadata fields
View SamplesTransfer cells (TCs) play important roles in facilitating enhanced rates of nutrient transport at key apoplasmic/symplasmic junctions along the nutrient acquisition and transport pathways in plants. TCs achieve this capacity by developing elaborate wall ingrowth networks which serve to increase plasma membrane surface area thus increasing the cell's surface area-to-volume ratio to achieve increased flux of nutrients across the plasma membrane. Phloem parenchyma (PP) cells of Arabidopsis leaf veins trans-differentiate to become PP TCs which likely function in a two-step phloem loading mechanism by facilitating unloading of photoassimilates into the apoplasm for subsequent energy-dependent uptake into the sieve element/companion cell (SE/CC) complex. We are using PP TCs in Arabidopsis as a genetic model to identify transcription factors involved in coordinating deposition of the wall ingrowth network. Confocal imaging of pseudo-Schiff propidium iodide-stained tissue revealed different profiles of temporal development of wall ingrowth deposition across maturing cotyledons and juvenile leaves, and a basipetal gradient of deposition across mature adult leaves. RNA-Seq analysis was undertaken to identify differentially expressed genes common to these three different profiles of wall ingrowth deposition. This analysis identified 68 transcription factors up-regulated two-fold or more in at least two of the three experimental comparisons, with six of these transcription factors belonging to Clade III of the NAC-domain family. Phenotypic analysis of these NAC genes using insertional mutants revealed significant reductions in levels of wall ingrowth deposition, particularly in a double mutant of NAC056 and NAC018, as well as compromised sucrose-dependent root growth, indicating impaired capacity for phloem loading. Collectively, these results support the proposition that Clade III members of the NAC domain family in Arabidopsis play important roles in regulating wall ingrowth deposition in PP TCs. Overall design: The sampling enabled three different temporal and spatial pair-wise comparisons for RNA-Seq analysis, namely: (i) cotyledons at Day 5 vs Day 10; (ii) Leaf 1 and Leaf 2 (first juvenile leaves) at Day 10 vs Day 16; and (iii) basal vs apical third (base vs tip) of Leaf 12 at Day 31. This analysis provided temporal and spatial comparisons of tissues with absent vs abundant wall ingrowth deposition in phloem parenchyma transfer cells.
Transcript Profiling Identifies NAC-Domain Genes Involved in Regulating Wall Ingrowth Deposition in Phloem Parenchyma Transfer Cells of <i>Arabidopsis thaliana</i>.
Specimen part, Subject
View SamplesSelective serotonin reuptake inhibitors (SSRIs) such as fluoxetine are the most common treatment for major depression. However, approximately 50% of depressed patients fail to achieve an effective treatment response. Understanding how gene expression systems relate to treatment responses may be critical for understanding antidepressant resistance. Transcriptome profiling allows for the simultaneous measurement of expression levels for thousands of genes and the opportunity to utilize this information to determine mechanisms underlying antidepressant treatment responses. However, the best way to relate this immense amount of information to treatment resistance remains unclear. We take a novel approach to this question by examining dentate gyrus transcriptomes from the perspective of a stereotyped fluoxetine-induced gene expression program. Expression programs usually represent stereotyped changes in expression levels that occur as cells transition phenotypes. Fluoxetine will shift transcriptomes so they lie somewhere between a baseline state and a full-response at the end of the program. The position along this fluoxetine-induced gene expression program (program status) was measured using principal components analysis (PCA). The same expression program was initiated in treatment-responsive and resistant mice but treatment response was associated with further progression along the fluoxetine-induced gene expression program. The study of treatment-related differences in gene expression program status represents a novel way to conceptualize differences in treatment responses at a transcriptome level. Understanding how antidepressant-induced gene expression program progression is modulated represents an important area for future research and could guide efforts to develop novel augmentation strategies for antidepressant treatment resistant individuals.
Global state measures of the dentate gyrus gene expression system predict antidepressant-sensitive behaviors.
Sex, Specimen part, Treatment
View SamplesWe used a smooth muscle cell-specific mineralocorticoid receptor knockout mouse to generate young and aged MR-intact and SMC-MR-KO aortic mRNA to examine the effect of age on vascular mRNA alterations in the presence and absence of SMC-MR.
Smooth Muscle Cell-Mineralocorticoid Receptor as a Mediator of Cardiovascular Stiffness With Aging.
Sex, Specimen part
View SamplesBackground: Transposable elements are known to influence the regulation of some genes. We aimed to determine which genes show altered gene expression when transposable elements are epigenetically activated.
Genome-wide identification of genes regulated in trans by transposable element small interfering RNAs.
Specimen part
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