O-GlcNAcylation is an essential, nutrient-sensitive post-translational modification, but its biochemical and phenotypic effects remain incompletely understood. To address this knowledge gap, we investigated the global transcriptional response to perturbations in O-GlcNAcylation. Unexpectedly, many transcriptional effects of O-GlcNAc transferase (OGT) inhibition were due to the activation of NRF2, the master regulator of redox stress tolerance. Moreover, we found that a signature of low OGT activity strongly correlates with NRF2 activation in multiple tumor expression datasets. Guided by this information, we identified KEAP1 (also known as KLHL19), the primary negative regulator of NRF2, as a direct substrate of OGT. We show that O-GlcNAcylation of KEAP1 at serine 104 is required for the efficient ubiquitination and degradation of NRF2. Interestingly, O-GlcNAc levels and NRF2 activation co-vary in response to glucose fluctuations, indicating that KEAP1 O-GlcNAcylation links nutrient sensing to downstream stress resistance. Our results reveal a novel regulatory connection between nutrient-sensitive glycosylation and NRF2 signaling, and provide a blueprint for future approaches to discover functionally important O-GlcNAcylation events on other KLHL family proteins in various experimental and disease contexts.
Glycosylation of KEAP1 links nutrient sensing to redox stress signaling.
Specimen part, Cell line
View SamplesWe discuss the use of pluripotent stem cell lines carrying fluorescent reporters driven by retinal promoters to derive three-dimensional (3-D) retina in culture and how this system can be exploited for elucidating human retinal biology, creating disease models in a dish, and designing targeted drug screens for retinal and macular degeneration. Furthermore, we realize that stem cell investigations are labor-intensive and require extensive resources. To expedite scientific discovery by sharing of resources and to avoid duplication of efforts, we propose the formation of a Retinal Stem Cell Consortium. In the field of vision, such collaborative approaches have been enormously successful in elucidating genetic susceptibility associated with age-related macular degeneration. Overall design: CRX+ flow sorted cells from human retina derived organoids were collected at 6 time points during differentiation (day (D) 37, 48, 67, 90, 134, 220).
Treatment Paradigms for Retinal and Macular Diseases Using 3-D Retina Cultures Derived From Human Reporter Pluripotent Stem Cell Lines.
Specimen part, Subject
View SamplesGenome-wide transcriptome analyses have allowed for systems- level insights into gene regulatory networks. Due to the limited depth of quantitative proteomics, however, our understanding of post-transcriptional gene regulation and its effects on protein complex stoichiometry are lagging behind. Here, we employ deep sequencing and iTRAQ technology to determine transcript and protein expression changes of a Drosophila brain tumour model at near genome-wide resolution. In total, we quantify more than 6,200 tissue-specific proteins, corresponding to about 70% of all transcribed protein-coding genes. Using our integrated data set, we demonstrate that post-transcriptional gene regulation varies considerably with biological function and is surprisingly high for genes regulating transcription. We combine our quantitative data with protein-protein interaction data and show that post-transcriptional mechanisms significantly enhance co-regulation of protein complex subunits beyond transcriptional co-regulation. Interestingly, our results suggest that only about 11% of the annotated Drosophila protein complexes are co-regulated in the brain. Finally, we refine the composition of some of these core protein complexes by analysing the co-regulation of potential subunits. Our comprehensive transcriptome and proteome data provide a rich resource for quantitative biology and offer novel insights into understanding post- transcriptional gene regulation in a tumour model. Overall design: Transcriptomes of 1-3 day old adult female Drosophila melanogaster heads of control and brat mutant were generated by deep sequencing, in triplicate, using Illumina GAIIx.
Transcriptome and proteome quantification of a tumor model provides novel insights into post-transcriptional gene regulation.
Subject
View SamplesGray leaf spot (GLS) disease of maize can be caused by either of two sibling fungal species Cercospora zeina or Cercospora zeae-maydis. These species differ in geographical distribution, for example to date only C. zeina is associated with GLS in African countries, such as South Africa. Maize inbred line B73, which is susceptible to GLS, was planted in the field, and subjected to natural infection with C. zeina. Samples were collected from lower leaves with substantial GLS lesions and younger upper leaves of the same plants with very few immature GLS lesions. The first aim of the experiment was to determine which maize genes are induced in response to C. zeina infection. The second aim was to identify C. zeina genes expressed in planta during a compatible interaction. The third aim was to determine whether the C. zeina cercosporin biosynthetic (CTB) genes are expressed in planta. C. zeina fails to produce cercosporin in vitro in contrast to C. zeae-maydis. Cercosporin is a phytotoxin that is thought to play a role in pathogenicity of several Cercospora spp., however its role in the pathogenicity strategy of C. zeina is currently under investigation. Overall design: To collect material that reflected a difference between C. zeina infected B73 leaves and control B73 leaf material, samples were collected from two lower GLS infected leaves (second and third leaf internode below ear), and two upper leaves with minimal GLS symptoms (second and third internode above ear), respectively. The two lower leaves from each plant were pooled prior to RNA extraction, and the two upper leaves from each plant were pooled prior to RNA extraction. Upper and lower leaf samples from three maize B73 plants were subjected to RNA sequencing individually. The three maize plants were selected randomly as one plant per row from three rows of ten B73 plants each.
Complementation of CTB7 in the Maize Pathogen Cercospora zeina Overcomes the Lack of In Vitro Cercosporin Production.
Specimen part, Subject
View SamplesWe used microarrays to detail the global programme of gene expression after 4 months of TFEB overexpression in the brain.
Selective clearance of aberrant tau proteins and rescue of neurotoxicity by transcription factor EB.
Specimen part, Treatment
View SamplesMYC-amplified medulloblastomas are highly lethal tumors. BET bromodomain inhibition was recently described to downregulate MYC-associated transcriptional activity in various cancer subtypes. To investigate whether JQ1, a BET bromodomain inhibitor is downregulation MYC and MYC-associated transcriptional activity, we performed global gene expression profiling of five medulloblastomas MYC-amplified patient-derived cell lines treated by JQ1 and the inactive form of JQ1.
BET bromodomain inhibition of MYC-amplified medulloblastoma.
Specimen part, Cell line, Treatment
View SamplesPurpose: Zebrafish neurons regenerate from Müller glia following retinal lesions. Genes and signaling pathways important for retinal regeneration in zebrafish have been described, but our understanding of how Mu¨ller glial stem cell properties are regulated is incomplete. Mammalian Mu¨ller glia possess a latent neurogenic capacity that might be enhanced in regenerative therapies to treat degenerative retinal diseases. Methods: To identify transcriptional changes associated with stem cell properties in zebrafish Mu¨ller glia, we performed a comparative transcriptome analysis from isolated cells at 8 and 16 hours following an acute, photic lesion, prior to the asymmetric division that produces retinal progenitors. Results: We report a rapid, dynamic response of zebrafish Müller glia, characterized by activation of pathways related to stress, NF-kappa B signaling, cytokine signaling, immunity, prostaglandin metabolism, circadian rhythm, and pluripotency, and an initial repression of Wnt signaling. When we compared publicly available transcriptomes of isolated mouse Mu¨ller glia from two retinal degeneration models, we found that mouse Müller glia showed evidence of oxidative stress, variable responses associated with immune regulation, and repression of pathways associated with pluripotency, development, and proliferation. Conclusions: Categories of biological processes/pathways activated following photoreceptor loss in regeneration-competent zebrafish Mu¨ller glia, which distinguished them from mouse Mu¨ller glia in retinal degeneration models, included: cytokine signaling (notably NF-kappa B), prostaglandin E2 synthesis, expression of core clock genes, and pathways/metabolic states associated with pluripotency. These regulatory mechanisms are relatively unexplored as potential mediators of stem cell properties likely to be important in Müller glial cells for successful retinal regeneration. Overall design: Transcriptional profiles of 0, 8, and 16 hour post-lesion zebrafish Müller glia (in triplicate) were generated by high-throughput sequencing in an Illumina GAIIx.
Rapid, Dynamic Activation of Müller Glial Stem Cell Responses in Zebrafish.
No sample metadata fields
View SamplesPurpose: Klf5 plays a critical role in the mouse ocular surface (Kenchegowda et al., 2011. Dev Biol. 356:5-18). Here, we compare wild-type (WT) and Klf5-conditional null (Klf5CN) corneal gene expression at postnatal day-11 (PN11) and PN56 to identify the Klf5-target genes. Methods: Gene expression was compared using Affymetrix microarrays with QPCR validation. Transient transfection assays examined the effect of Klf5 on selected target gene promoter activities. Whole-mount corneal immunofluorescent staining examined neovascularization and CD45+ macrophage influx. Results: Expression of 714 and 753 genes was increased, and 299 and 210 genes decreased in PN11 and PN56 Klf5CN corneas, respectively, with 366 concordant increases, 72 concordant decreases and 3 discordant changes. Canonical pathway analysis identified 35 and 34 significantly (p<0.001) enriched pathways at PN11 and PN56, respectively, with 24 common pathways. PN56 Klf5CN corneas shared 327 increases and 91 decreases with the previously described Klf4CN corneas (Swamynathan et al., 2008. IOVS 49:3360-70). Angiogenesis and immune response-related genes were affected consistent with lymphangiogenesis and macrophage influx in Klf5CN corneas, respectively. Expression of 1574 genes was increased and 1915 decreased, in the WT PN56 compared with PN11 corneas. Expression of many collagens, matrix metalloproteinases and other extracellular matrix associated genes decreased in WT corneas between PN11 and PN56, while that of solute carrier family members increased. Conclusions: Differences in PN11 and PN56 corneal Klf5-target genes reveal dynamic changes in Klf5 functions during corneal maturation. Klf4- and Klf5-target genes do not overlap, consistent with their non-redundant roles in the mouse cornea.
Critical role of Klf5 in regulating gene expression during post-eyelid opening maturation of mouse corneas.
No sample metadata fields
View SamplesConditional disruption of Klf4 in the ectoderm-derived tissues of the eye results in defective cornea, conjunctiva and the lens.
Regulation of mouse lens maturation and gene expression by Krüppel-like factor 4.
Specimen part
View SamplesOur data suggest that CNTF remodels the transcription profile of Mller (glial) cells leading to induction of networks associated with transcription, cell cycle regulation and inflammatory response. CNTF also appears to function as an inducer of gliosis in the retina. These studies provide new insights into the biological functions of cytokines in the retina.
Ciliary neurotrophic factor induces genes associated with inflammation and gliosis in the retina: a gene profiling study of flow-sorted, Müller cells.
Specimen part, Treatment, Time
View Samples