During fasting, increases in circulating pancreatic glucagon maintain glucose balance by up-regulating hepatic gluconeogenesis. Triggering of the cAMP pathway stimulates the gluconeogenic program through the phosphorylation of CREB and via the de-phosphorylation of the CREB coactivator CRTC2. Hormonal and nutrient signals are also thought to modulate gluconeogenic genes by promoting epigenetic changes that facilitate assembly of the transcriptional machinery, although the nature of these modifications is unclear. Here we show that histone H3 acetylation at Lys 9 (H3K9Ac) is elevated over gluconeogenic genes during fasting and in diabetes, where it contributes to increases in hepatic glucose production. Following its dephosphorylation, CRTC2 promoted increases in H3K9Ac by mediating the recruitment of the lysine acetyltransferase 2B (KAT2B) and WD repeat-containing protein 5 (WDR5), a core subunit of histone methyltransferase (HMT) complexes. In turn, KAT2B and WDR5 stimulated the gluconeogenic program through a self-reinforcing cycle whereby increases in H3K9Ac further potentiated CRTC2 occupancy at CREB binding sites. Breaking this cycle, by depletion of KAT2B or WDR5, decreased gluconeogenic gene expression. As administration of a small molecule KAT2B antagonist lowered circulating blood glucose concentrations in insulin resistance, our results demonstrate how this enzyme may be a useful target for diabetes treatment.
Glucagon regulates gluconeogenesis through KAT2B- and WDR5-mediated epigenetic effects.
Sex, Age, Specimen part
View SamplesAnalysis of gene expression of Pdx-EGFP1+ pancreatic progenitors before or after co-culture at mRNA level. The hypothesis tested in the study was that the overall gene expression in Pdx1-EGFP+ does not alter after co-culture with endothelial cells. The result supported our hypothesis. Overall design: Total RNA isolated from Pdx1-EGFP+ progenitors from the Pdx1-EGFP HUES8 cell-derived pancreatic progenitor population before (none) and after co-culture (AKT-HUVEC, MPEC, or BJ) Fig 2d in publication.
Endothelial cells control pancreatic cell fate at defined stages through EGFL7 signaling.
No sample metadata fields
View SamplesMitochondrial biogenesis is regulated by signaling pathways sensitive to extracellular conditions and to the internal environment of the cell. We found that deletion of protein phosphatase 2A (PP2A) or of protein phosphatase 6 (PP6) diminishes the nuclear transcriptional response associated with mtDNA damage. Overall design: Six samples were analyzed to determine message RNA levels.
Deletion of conserved protein phosphatases reverses defects associated with mitochondrial DNA damage in Saccharomyces cerevisiae.
Specimen part, Subject
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Acute depletion of Tet1-dependent 5-hydroxymethylcytosine levels impairs LIF/Stat3 signaling and results in loss of embryonic stem cell identity.
Specimen part, Cell line
View SamplesThe TET family of FE(II) and 2-oxoglutarate-dependent enzymes (Tet1/2/3) promote DNA demethylation by converting 5-methylcytosine to 5-hydroxymethylcytosine (5hmC), which they further oxidize into 5-formylcytosine and 5-carboxylcytosine. Tet1 is robustly expressed in mouse embryonic stem cells (mESCs) and has been implicated in mESC maintenance. Here we demonstrate that, unlike genetic deletion, RNAi-mediated depletion of Tet1 in mESCs led to a significant reduction in 5hmC and loss of mESC identity. The differentiation phenotype due to Tet1 depletion positively correlated with the extent of 5hmC loss. Meta-analyses of genomic datasets suggested interaction between Tet1 and leukemia inhibitory factor (LIF) signaling. LIF signaling is known to promote self-renewal and pluripo-tency in mESCs partly by opposing MAPK/ERK mediated differentiation. Withdrawal of LIF leads to differentiation of mESCs. We discovered that Tet1 depletion impaired LIF-dependent Stat3-mediated gene activation by affecting Stat3's ability to bind to its target sites on chromatin. Nanog overexpression or inhibition of MAPK/ERK signaling, both known to maintain mESCs in the absence of LIF, rescued Tet1 depletion, further supporting the dependence of LIF/Stat3 signaling on Tet1. These data support the conclusion that analysis of mESCs in the hours/days immediately following efficient Tet1 depletion reveals Tet1s normal physiological role in maintaining the pluripotent state that may be subject to homeostatic compensation in genetic models.
Acute depletion of Tet1-dependent 5-hydroxymethylcytosine levels impairs LIF/Stat3 signaling and results in loss of embryonic stem cell identity.
Cell line
View SamplesTo estimate mRNA steady-state levels we used RNA extracted from logarithmically growing fisson yeast cells on Affymetrix Yeast 2.0 Genechip arrays. The signal intensities from two independent biological repeats were averaged, resulting in measurements for 4818 out of 4962 nuclear protein-coding genes.
A network of multiple regulatory layers shapes gene expression in fission yeast.
Sex, Subject
View SamplesTranscriptional profiling was utilized to define the biological pathways of gingival epithelial cells modulated by mono- and complex co-culture with oral commensal S. gordonii and pathogenic P. gingivalis.
The degree of microbiome complexity influences the epithelial response to infection.
No sample metadata fields
View SamplesDespite RNAi-based screens to uncover genes controlling embryonic stem cell (ESC) identity, the pluripotency network remains poorly characterized, as does the precise molecular mechanisms underlying the balance between self-renewal and differentiation. Here we carried out a systematic meta-analysis of published gene expression data to rank-order genes based on their likelihood of regulating ESC identity. Not only did our analysis correctly rank known pluripotency-associated genes atop the list, but it also helped unearth many novel determinants of ESC identity including several components of functionally distinct complexes, as determined using RNAi. We focus on our top-hit Nucleolin, and characterize its mechanistic role in the maintenance of ESC homeostasis by shielding from differentiation-inducing redox imbalance-induced oxidative stress. Notably, we identify a conceptually novel mechanism involving a Nucleolin-dependent bistable switch regulating the homeostatic balance between self-renewal and differentiation in ESCs. Our gene ranks represent a rich and valuable resource for uncovering novel ESC regulators.
Integrative framework for identification of key cell identity genes uncovers determinants of ES cell identity and homeostasis.
Cell line
View SamplesTransformed and tumorigenic cells require increased deoxyribonucleotide synthesis to fuel the genome replication that sustains their unregulated cell cycle and proliferation. Therefore, it is likely that the cell cycle and nucleotide metabolism are linked. The cell cycle inhibitor p16 is a critical tumor suppressor that is lost as an early event in many human cancers. While loss of p16 is known to play a role in deregulating the cell cycle, whether loss of p16 expression affects nucleotide metabolism is unknown. Overall design: mRNA profiles of IMR90 control, dNTP depletion-induced senesnce (shRRM2) and dNTP depletion-induced senescence bypass (shRRM2/shp16) were generated by deep sequencing, in triplicate, using HiSeq 2500 sequencer (Illumina)
Suppression of p16 Induces mTORC1-Mediated Nucleotide Metabolic Reprogramming.
Cell line, Subject
View SamplesThe generation of induced pluripotent stem cells (iPSCs) from differentiated cells following forced expression of Oct4, Klf4, Sox2 and c-Myc (OKSM) is slow and inefficient, suggesting that transcription factors have to overcome somatic barriers that resist cell fate change. Here, we performed an ubiased serial shRNA enrichment screen to identify novel repressors of somatic cell reprogramming into iPSCs. This effort uncovered the sumoylation effector protein Sumo2 as one of the strongest roadblocks to iPSC formation. Depletion of Sumo2 both enhances and accelerates reprogramming, yielding transgene-independent, chimera-competent iPSCs after as little as 36 hours of OKSM expression. We further show that the Sumo2 pathway acts independently of exogenous c-Myc expression and in parallel with small molecule enhancers of reprogramming. Critically, suppression of SUMO2 also promotes the generation of human iPSCs. Together, our results reveal sumoylation as a crucial post-transcriptional mechanism that resists the acquisition of pluripotency from fibroblasts using defined factors.
A Serial shRNA Screen for Roadblocks to Reprogramming Identifies the Protein Modifier SUMO2.
Sex, Specimen part, Time
View Samples