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Unknown,Transcriptomics,Genomics,Proteomics

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Epigenetic and transcriptional regulation of starvation-induced atrophy and autophagy programs by Foxk1 and Sin3A

ABSTRACT: Autophagy is the primary catabolic process triggered in response to starvation. Although autophagic regulation within the cytosolic compartment is well established, it is becoming clear that nuclear events also regulate the induction or repression of autophagy. Nevertheless, a thorough understanding of the mechanisms by which sequence-specific transcription factors modulate expression of genes required for autophagy is lacking. Here, we identify Foxk proteins (Foxk1 and Foxk2) as transcriptional repressors of autophagy in muscle cells and fibroblasts. Interestingly, Foxk1/2 serve to counter-balance another forkhead transcription factor, Foxo3, which induces an overlapping set of autophagic and atrophic targets in muscle. Foxk1/2 specifically recruits Sin3A-HDAC complexes to restrict acetylation of histone H4 and expression of critical autophagy genes. Remarkably, mTOR promotes the transcriptional activity of Foxk1 by facilitating nuclear entry to specifically limit basal levels of autophagy in nutrient-rich conditions. Our study highlights an ancient, conserved mechanism whereby nutritional status is interpreted by mTOR to restrict autophagy by repressing essential autophagy genes via Foxk-Sin3-mediated transcriptional control. Examination of (1) chromatin binding of Foxk1 and Sin3A in non-starved myoblasts and (2) gene expression profiling upon either starvation or siRNA-mediated depletion of Foxk1 relative to a non-starved control.

ORGANISM(S): Mus musculus

SUBMITTER: Brian Dynlacht

PROVIDER: E-GEOD-56932 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Epigenetic and transcriptional regulation of starvation-induced atrophy and autophagy programs by Foxk1 and Sin3A

Project description:Autophagy is the primary catabolic process triggered in response to starvation. Although autophagic regulation within the cytosolic compartment is well established, it is becoming clear that nuclear events also regulate the induction or repression of autophagy. Nevertheless, a thorough understanding of the mechanisms by which sequence-specific transcription factors modulate expression of genes required for autophagy is lacking. Here, we identify Foxk proteins (Foxk1 and Foxk2) as transcriptional repressors of autophagy in muscle cells and fibroblasts. Interestingly, Foxk1/2 serve to counter-balance another forkhead transcription factor, Foxo3, which induces an overlapping set of autophagic and atrophic targets in muscle. Foxk1/2 specifically recruits Sin3A-HDAC complexes to restrict acetylation of histone H4 and expression of critical autophagy genes. Remarkably, mTOR promotes the transcriptional activity of Foxk1 by facilitating nuclear entry to specifically limit basal levels of autophagy in nutrient-rich conditions. Our study highlights an ancient, conserved mechanism whereby nutritional status is interpreted by mTOR to restrict autophagy by repressing essential autophagy genes via Foxk-Sin3-mediated transcriptional control.

2014-11-17 | GSE56932 | GEO

Genome-wide maps of Sin3A and Sin3B binding in C2C12 myoblasts and differentiated myotubes

Project description:Sin3A and Sin3B bind to distinct and overlapping target sites. Sin3 proteins bind to distinct sites in cycling myoblasts whereas there is a converge of Sin3A and Sin3B proteins to sites in differentiated myotubes. We identified a subset of Sin3 target genes involved in muscle differentiation and physiology and showed that conditional ablation of Sin3 proteins in vivo in mouse results in sarcomere defects Examination of Sin3A and Sin3B binding during myogenesis

2011-01-01 | E-GEOD-22554 | biostudies-arrayexpress

RNA-seq of human embryonic stem cells H1 ESC cells and the differentiated NPC cells with FOXK1/2 and SIN3A knock down and the control condition.

Project description:In order to investigate the genome-wide binding profile of the forkhead transcription factor FOXK2 in human embryonic stem cells (ESCs) and downstream cell types, we generated the RNA-seq data with FOXK1/2 and SIN3A siRNA in H1 ESC cells and FOXK1/2 siRNA in the differentiated NPC cells.

2021-09-08 | E-MTAB-9639 | biostudies-arrayexpress

PPARα mouse liver cistrome

Project description:Autophagy is an evolutionally conserved catabolic process that recycles nutrients upon starvation and maintains cellular energy homeostasis1-3. Its acute regulation by nutrient sensing signaling pathways is well described, but its longer-term transcriptional regulation is not. The nuclear receptors PPARα and FXR are activated in the fasted or fed liver, respectively4,5. Here we show that both regulate hepatic autophagy. Pharmacologic activation of PPARα reverses the normal suppression of autophagy in the fed state, inducing autophagic lipid degradation, or lipophagy. This response is lost in PPARα knockout (PPARα-/-) mice, which are partially defective in the induction of autophagy by fasting. Pharmacologic activation of the bile acid receptor FXR strongly suppresses the induction of autophagy in the fasting state, and this response is absent in FXR knockout (FXR-/-) mice, which show a partial defect in suppression of hepatic autophagy in the fed state. PPARα and FXR compete for binding to shared sites in autophagic gene promoters, with opposite transcriptional outputs. These results reveal complementary, interlocking mechanisms for regulation of autophagy by nutrient status. Mouse liver PPARα cistromes in fed 8-week-old male WT or PPARα KO mice treated with or without its synthetic agonist ligand GW7647twice a day were generated by deep sequencing in quadruplicate using illumina

2014-09-27 | E-GEOD-61817 | biostudies-arrayexpress

Mus musculus

Project description:Epigenetic and transcriptional regulation of starvation-induced atrophy and autophagy programs by Foxk1 and Sin3A

| PRJNA244979 | ENA

Autophagy driven by a master regulator of hematopoiesis

Project description:Developmental and homeostatic remodeling of cellular organelles is mediated by a complex process termed autophagy. The cohort of proteins that constitute the autophagy machinery function in a multistep biochemical pathway. Though components of the autophagy machinery are broadly expressed, autophagy can occur in specialized cellular contexts, and mechanisms underlying cell type-specific autophagy are poorly understood. We demonstrate that the master regulator of hematopoiesis GATA-1 directly activates transcription of genes encoding the essential autophagy component Microtubule Associated Protein 1 Light Chain 3B (LC3B) and its homologs (MAP1LC3A, GABARAP, GABARAPL1, GATE-16). In addition, GATA-1 directly activates genes involved in the biogenesis/function of lysosomes, which mediate autophagic protein turnover. We demonstrate that GATA-1 utilizes the forkhead protein FoxO3 to activate select autophagy genes. GATA-1-dependent LC3B induction is tightly coupled to accumulation of the active form of LC3B and autophagosomes, which mediate mitochondrial clearance as a critical step in erythropoiesis. These results illustrate a novel mechanism by which a master regulator of development establishes a genetic network to instigate cell type-specific autophagy. Genome-wide maps of GATA1 factor occupancy in primary human PBMC derived erythroblasts

2011-09-30 | E-GEOD-32491 | biostudies-arrayexpress

Depletion of Foxk transcription factors causes genome-wide transcriptional misregulation and developmental arrest in zebrafish embryos

Project description:Foxk proteins are transcriptional regulators implicated in key biological processes such as glycolysis, autophagy and cell cycle regulation, among others. Here we employ targeted morpholino knockdown to deplete Foxk1, Fokx2, and Foxk2-1 proteins in developing zebrafish embryos. We demonstrate that the loss of Foxk transcription factors causes genome-wide transcriptional misregulation, characterised by upregulation of autophagy-related genes and downregulation of cell cycle regulators. The phenotype is embryonic lethal with the majority of embryos not surviving past 24hpf.

2020-12-01 | E-MTAB-9777 | biostudies-arrayexpress

O-GlcNAcylation of FOXK1 orchestrates the E2F pathway

Project description:Gene transcription is a highly regulated process, and deregulation of transcription factors activity underlie numerous pathologies including cancer. FOXK1 and FOXK2 (FOXK1/2) transcription factors have recently emerged as important regulators of cell metabolism, autophagy and cell differentiation. While FOXK1/2 possesses many overlapping functions in normal biology, their specific functions as well as deregulation of their transcriptional activity in cancer is less clear and often contradictory. FOXK1, but less FOXK2, is known to have oncogenic properties as higher expression levels of FOXK1 has been observed in several cancers and is correlated with tumor progression, invasion, and metastasis. However, the molecular mechanism by which FOXK1 exert its oncogenic properties in caner remains unknown. Here we show that elevated expression of FOXK1, but not FOXK2, in normal human fibroblasts promotes transcription of E2F target genes associated with increased proliferation and delayed senescence entry. Fibroblasts overexpressing FOXK1 are also more prone to cellular transformation with minimal oncogenic combinations, suggesting important oncogenic proprieties of FOXK1. Mechanistically, we found that FOXK1, but not FOXK2, is specifically modified by O-GlcNAcylation. FOXK1 O-GlcNAcylation is modulated during the cell cycle and its highest levels coincides with the G1/S phase transition. Moreover, FOXK1 O-GlcNAcylation is increased following cell transformation and loss of this modification leads to decreased FOXK1 ability to promote cellular transformation and tumor growth. Cells overexpressing FOXK1 O-GlcNAcylation-defective mutants have lower E2F1 expression, cell proliferation, and tumour growth. Our results define a distinct role of FOXK1 via O-GlcNAcylation in controlling the cell cycle through the orchestration of the E2F pathway.

2024-06-10 | PXD050014 | Pride

Gene regulation in autophagy and apoptosis juncture

Project description:Autophagy to apoptosis switching event is an unexplored area. We were interested to explore the gene expression profile at this juncture. Our Microarray data emphasized that among all eNOS and p62 genes were markedly induced. In fuctional level eNOS expression activates mTORC1 followed by inhibition of autophagy. This ultimately allowed accumulation of p62 . Intraccellular accumulation of p62 sequestered unfolded toxic protein aggregates in mitochondria and ER resulting in to impaired redox regulation. Intraccelular ROS generation further sensitized cells for apoptosis and tilted autophagic response to apoptosis. Cells were treated with Tunicamycin as an inducer of both autophagy and apoptosis. At early stage of Tunicamycin treatment 24h , prostate cancer cell PC3 showed activation of autophagic process where apoptosis was not evident. Sustained ER stress with Tunicamycin induced late apoptoisis at 72h of treatment. Hence we isolated total RNA from Untreated cells, cells with Tunicamycin treatment after 24h and 72h. Further the RNA were used to perform whole genome microarray to analyze the gene expression profile at autophagy and apoptosis juncture. The selected genes were also validated by qPCR and western bot. Morover RNAi study were implemented to evaluate the signaling crosstalk at the juncture of autophagy and apoptosis.

2014-05-22 | E-GEOD-38643 | biostudies-arrayexpress

Miz1 is required to maintain autophagic flux

Project description:Miz1 is a zinc finger protein that regulates expression of cell cycle inhibitors as part of a complex with Myc. Cell cycle-independent functions of Miz1 are poorly understood. Here, we use a Nestin-Cre transgene to delete an essential domain of Miz1 in the central nervous system (Miz1M-NM-^TPOZNes). Miz1M-NM-^TPOZNes mice display cerebellar neurodegeneration characterized by the progressive loss of Purkinje cells. Chromatin immunoprecipitation sequencing and biochemical analyses show that Miz1 activates transcription upon binding to a non-palindromic sequence present in core promoters. Target genes of Miz1 encode regulators of autophagy and proteins involved in vesicular transport that are required for autophagy. Miz1M-NM-^TPOZ neuronal progenitors and fibroblasts show reduced autophagic flux. Consistently, polyubiquitinated proteins and p62/Sqtm1 accumulate in the cerebella of Miz1M-NM-^TPOZNes mice, characteristic features of defective autophagy. Our data suggest that Miz1 may link cell growth and ribosome biogenesis to the transcriptional regulation of vesicular transport and autophagy. ChIP-Seq with H190 and G18 on an Illumina Genome Analyzer IIx.

2013-09-27 | E-GEOD-48602 | biostudies-arrayexpress

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