Project description:Cancer cells undergo transcriptional reprogramming to drive tumorigenesis and caner progression. Here, we identified the transcriptional complex, NELF (Negative elongation factor), as an important regulator of this process. Using cancer cell lines and patient-derived tumor organoids, we demonstrated that loss of NELF inhibits breast cancer. Specifically, we found that epithelial-mesenchymal transition (EMT) and stemness-associated genes are downregulated in NELF-depleted breast cancer cells. Afterwards, we pinpointed that SLUG, a key EMT transcription factor, was a top hit of NELF interactome during EMT progression. Furthermore, ChIP-seq analysis revealed that loss of NELF led to impaired SLUG binding on chromatin. Through integrative transcriptomic and genomic analyses, we identified the histone acetyltransferase, KAT2B, as a key functional target of NELF-E-SLUG. Genetic and pharmacological inactivation of KAT2B ameliorate expression of critical EMT marker genes, phenocopying NELF ablation. Elevated NELF-E and KAT2B expressions are associated with poorer prognosis in breast cancer patients, highlighting the clinical relevance of our findings. Taken together, we uncovered a crucial role of the NELF-E-KAT2B epigenetic axis in breast cancer carcinogenesis.
Project description:Cancer cells undergo transcriptional reprogramming to drive tumor progression and metastasis. Here, we identified the transcriptional complex, NELF (Negative elongation factor), as an important regulator of this process. Using cancer cell lines and patient-derived tumor organoids, we demonstrated that loss of NELF inhibits breast cancer tumorigenesis and metastasis. Specifically, we found that epithelial-mesenchymal transition (EMT) and stemness-associated genes are downregulated in NELF-depleted breast cancer cells. Quantitative Multiplexed Rapid Immunoprecipitation Mass spectrometry of Endogenous proteins (qPLEX-RIME) of NELF-E, a key subunit of NELF, reveals significant rewiring of NELF-E-associated chromatin partners as a function of EMT, and further illuminates a co-option of NELF-E with the key EMT transcription factor SLUG. Accordingly, loss of NELF-E led to impaired SLUG binding on chromatin. Through integrative transcriptomic and genomic analyses, we identified the histone acetyltransferase, KAT2B, as a key functional target of NELF-E-SLUG. Genetic and pharmacological inactivation of KAT2B ameliorate expression of critical EMT marker genes, phenocopying NELF ablation. Elevated NELF-E and KAT2B expressions are associated with poorer prognosis in breast cancer patients, highlighting the clinical relevance of our findings. Importantly, KAT2B knockout mice are viable, raising the exciting prospect of targeting this dependency therapeutically. Taken together, we uncovered a crucial role of the NELF-E-KAT2B epigenetic axis in breast cancer carcinogenesis.
Project description: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. A subset of cAMP responsive genes depend on specific recruitment of KAT2B (pcaf), which in concert with WDR5 acetylates H3K9. By selectively depleting hepatocytes for KAT2B or WDR5 prior to glucagon stimulation we explore, which genes rely on KAT2B and WDR5 activity. mKAT2B or mWDR5 were knocked down in primary mouse hepatocytes using adenoviral transduction with appropriate shRNAs. Control cells were transduced with a non-specific (NS) shRNA. 72 hours post transduction some cells were stimulated for 90 minutes with 100nM glucagon and others with PBS. Total RNA was purified and subjected to micro-RNA analysis. All samples are pools of RNA from three sepearate dishes. One replicate is included for most samples.
Project description:The Endoplasmic Reticulum (ER) unfolded protein response (UPRer) pathway plays an important role for pancreatic β cells to adapt their cellular responses to environmental cues and metabolic stress. Although altered UPRer gene expression appears in rodent and human type 2 diabetic (T2D) islets, the underlying molecular mechanisms remain unknown. We show here that germ-line and β-cell specific disruption of the lysine acetyltransferase 2B (Kat2b) gene in mice leads to impaired insulin secretion and glucose intolerance. Genome wide analysis of Kat2b-regulated genes and functional assays revealed a critical role for KAT2B in maintaining UPRer gene expression and subsequent β-cell function. Importantly, Kat2b expression was decreased in db/db and in human T2D islets and correlated with UPRer genes in normal human islets. In conclusion, KAT2B is a crucial transcriptional regulator for adaptive β-cell function during metabolic stress by controlling UPRer and represents a promising target for T2D prevention and treatment
Project description:NELF-A phosphorylation by P-TEFb is a key event in the pausing release. We conduct IMAC-LC-MS-MS to identified NELF-A phosphorylation site by activation P-TEFb kinase.
Project description:Jurkat T-cells were latently infected with a defective HIV provirus carrying a GFP reporer gene. The cells were superinfected with a lentiviral vector expressing shRNA to NELF-E. The impact of NELF-depletion on RNAP II distribution on cellular genes and the HIV provirus was measured by ChIP-Seq. Data sets contained between 45 and 56 million mapped reads Four samples were compared: Control shRNA, NELF-E shRNA, Control shRNA plus TNF-a, NELF-E shRNA plus TNF-a.
Project description:Investigation of whole genome gene expression level changes in hepatocellular carcinoma cell line hepG2 in regular culture, hepG2-slug in regular culture and hepG2-slug on Matrigel. Whole genome gene expression level changes have been compared in hepatocellular carcinoma cell line hepG2 in regular culture, hepG2-slug in regular culture and hepG2-slug on Matrigel.
Project description:This SuperSeries is composed of the following subset Series: GSE41026: Expression analysis of HepG2, HepG2-slug and HepG2-slug on Matrigel GSE41027: Chip-chip from HepG2 cells and HepG2 cells with slug overexpression Refer to individual Series
Project description:Negative elongation factor (NELF) is known to enforce promoter-proximal pausing of RNA polymerase II (Pol II), a pervasive phenomenon observed across multicellular genomes. However, the physiological impact of NELF on tissue homeostasis remains unclear. Here we show for the first time that whole-body conditional deletion of the B subunit of NELF (NELF-B) in adult mice results in cardiomyopathy and impaired response to cardiac stress. Tissue-specific knockout of NELF-B confirms its cell-autonomous function in cardiomyocytes. NELF directly supports transcription of those genes encoding rate-limiting enzymes in fatty acid oxidation and the tricarboxylic acid (TCA) cycle. NELF also shares extensively transcriptional target genes with peroxisome proliferator-activated receptors alpha (PPARalpha), a master regulator of energy metabolism in myocardium. Mechanistically, NELF helps stablize the transcription initation complex at the metabolism-related genes. Our findings strongly indicate that NELF is part of the PPARalpha-mediated transcription regulatory network that maintains metabolic homeostasis in cardiomyocytes. 3 Nelf-b f/f and 3 Nelf-b f/f; CreER female mice were injected with Tamoxifen at 8 wk old. Heart tissue were harvested at 20 wks old and used for RNA preparation.
Project description:Investigation of whole genome gene expression level changes in hepatocellular carcinoma cell line hepG2 in regular culture, hepG2-slug in regular culture and hepG2-slug on Matrigel. Whole genome gene expression level changes have been compared in hepatocellular carcinoma cell line hepG2 in regular culture, hepG2-slug in regular culture and hepG2-slug on Matrigel. Roche NimbleGen micro-array analysis was employed to assess global genome expression in HepG2 in regular culture, HepG2-slug in regular culture and HepG2-slug on Matrigel. The results demonstrated that the up-regulated genes and the down-regulated genes increased significantly when HepG2-slug cells with VM forming ablity were cultured on Matrigel and formed VM.