Regulation of LbetaT2 gonadotrope gene expression by GnRH pulses
ABSTRACT: LbetaT2 cells exposed to different number and concentration of GnRH pulses over 4 hours during in vitro perfusion culture We used MU74Av2 arrays to profile gene expression in response to different pulse frequency and pulse amplitude RNA extracted at end of 4 h of perfusion
Project description:Glioblastomas show heterogeneous histological features, in which tumor cells show distinct phenotypic states that confer different functional attributes. This functional and morphological heterogeneity characterizes aggressive glioblastoma; however, molecular mechanisms underlying the heterogeneity are poorly understood. Glioma stem-like cells (GSCs) are considered able to aberrantly differentiate into diverse cell types and may contribute the establishment of tumor heterogeneity. Using the GSC model, we investigated the differentially expressed microRNAs(miRNAs) and associated epigenetic mechanism that regulate the differentiation of GSCs. MiRNA-microarray showed that 13 and 34 miRNAs were commonly upregulated and downregulated in two independent GSC lines during differentiation, respectively. Among those miRNAs, quantitative-PCR analysis showed that miR-1275 was consistently downregulated during the GSC differentiation along with the upregulation of its target, CLDN11, a marker of oligodendroglial-lineage differentiation. Compellingly, inhibition of miR-1275 with specific antisense oligonucleotide (anti-miR-1275) in GSC increased the expression of CLDN11, together with significant growth suppression. Epigenetic analysis revealed that gain of histone H3 lysine 27 trimethylation (H3K27me3) and loss of H3K9Ac in the pri-miR-1275 promoter were closely associated with the miR-1275 expression. Treatment of 3-Dezaneplanocin-A, an inhibitor of H3K27 methyltransferase, impaired the GSC differentiation in parallel with sustained miR-1275 expression. Our results illuminated the epigenetic regulatory pathways of miR-1275 closely associated with oligodendroglial differentiation, which may contribute to the tissue heterogeneity formation of glioblastomas. Inhibition of miR-1275 induces the GSC differentiation and suppresses tumor cell proliferation, miR-1275 may be a potential therapeutic target for glioblastomas. Human miRNA Microarray V3 kits (G4470C; Agilent Technologies, Santa Clara, California) were used according to the manufacturer’s protocols. This microarray system contains probes for all 866 human and 89 human viral miRNAs reported from the Sanger database v12.0 (http://microrna.sanger.ac.uk/sequences/). Each miRNA species is printed 20 times with replicate probes on the array. Total RNA was isolated with TRIzol reagent (Invitrogen). One hundred ng of total RNA was labeled with pCp-Cy3 (Agilent Technologies) and 15 units of T4 RNA ligase (GE Healthcare, Little Chalfont, Buckinghamshire, UK) at 16°C for 2 hours. Labeled samples were purified with MicroBio-Spin 6 columns (Bio-Rad, Richmond, CA) and hybridized to microarray at 55 °C with rotation at 20 rpm for 20 hours. Microarrays were scanned by an Agilent Scanner (Agilent Scan Control 7.0 software) and analyzed using Agilent Feature Extraction 10.7 software for miRNA microarray.
Project description:We hypothesize that cultured macrophages directly exposed intermittent hypoxia will have a greater change in expression in genes related to inflammatory response than macrophages exposed to sustained hypoxia. We will evaluate gene expression using microarray analysis of RNA collected from RAW 264.7 macrophages cultured under the following environmental conditions: 1) 4 hours of intermittent hypoxia (2 minute cycles: 90 seconds at 40 Torr and 30 seconds at 8 Torr), 2) 4 hours of sustained hypoxia (8 Torr), and 3 ) standard tissue culture conditions (141 Torr; reference).
Project description:We hypothesize that the culture media collected from macrophages exposed to intermittent hypoxia will induce a greater pro-inflammatory gene profile in naïve cultured macrophages than will culture media collected from macrophages exposed to sustained hypoxia. We will evaluate gene expression using microarray analysis of RNA collected from RAW 264.7 macrophages cultured for 24 hours in DMEM media obtained from 1) cells cultured with intermittent hypoxia (2 minute cycles: 90 seconds at 40 Torr and 30 seconds at 8 Torr), 2) media exposed to intermittent hypoxia, 3) cells cultured with sustained hypoxia (8 Torr), 4) media exposed to sustained hypoxia and 4) standard tissue culture conditions (fresh DMEM media; reference).
Project description:Generated AZA resistant cell line (TAR) and analysis markedly different gene expression levels between THP-1 and TAR. Two condition experiment, THP-1 control vs. AZA resistant cell line.
Project description:Insulin is a potent regulator of protein metabolism. Here we describe a time-resolved map of insulin-regulated protein turnover in 3T3-L1 adipocytes using metabolic pulse-chase labelling and high-resolution mass spectrometry.
Project description:Normal cells require continuous exposure to growth factors, in order to cross a restriction point and commit to cell cycle progression. This can be replaced by two short, appropriately spaced pulses of growth factors, where the first pulse primes a process, which is completed by the second pulse, and enables restriction point crossing. Through integration of comprehensive proteomic and transcriptomic analyses of each pulse, we identified three processes that regulate restriction point crossing: (i) The first pulse induces essential metabolic enzymes and activates p53-dependent restraining processes. (ii) The second pulse eliminates, via the PI3K/AKT pathway, the suppressive action of p53, as well as (iii) sets an ERK-EGR1 threshold mechanism, which digitizes graded external signals into an all-or-none decision obligatory for S-phase entry. Together, our findings uncover novel gating mechanisms, which ensure that cells ignore fortuitous growth factors, and undergo proliferation only in response to consistent mitogenic signals. 17 samples; one control sample, time zero.
Project description:Primary telomerase RNA transcripts are processed into shorter mature forms that assemble into a complex with the catalytic subunit and provide the template for telomerase activity. In diverse fungi telomerase RNA 3’ end processing involves a single cleavage reaction by the spliceosome akin to the first step of splicing. Longer forms of human telomerase RNA (hTR) have been reported, but how the mature form of precisely 451 nucleotides is generated is still unknown. We now show that the splicing inhibitor isoginkgetin causes accumulation of long hTR transcripts, but find no evidence for a direct role for splicing in hTR processing. Instead, isoginkgetin mimics the effects of inhibiting the RNA exosome. Depletion of exosome components and accessory factors reveals functions for the cap binding complex (CBC) and the nuclear exosome targeting (NEXT) complex in hTR turnover. Whereas longer transcripts are predominantly degraded, shorter precursor RNAs are oligo-adenylated by TRF4-2 and either processed by poly (A) specific ribonuclease (PARN) or degraded by the exosome. Our results reveal that hTR biogenesis involves a kinetic competition between RNA processing and quality control pathways and suggest new treatment options for dyskeratosis congenita caused by mutations in RNA processing factors. We cloned and sequenced 3’ ends by RLM-RACE coupled with high-throughput sequencing to gain further insights into hTR processing.
Project description:Development of systems allowing the maintenance of native properties of mesenchymal stromal cells (MSC) is a critical challenge for studying physiological functions of skeletal progenitors, as well as towards cellular therapy and regenerative medicine applications. Conventional stem cell culture in monolayer on plastic dishes (2D) is associated with progressive loss of functionality, likely due to the absence of a biomimetic microenvironment and the selection of adherent populations. Here we demonstrate that 2D MSC expansion can be entirely bypassed by culturing freshly isolated bone marrow cells within the pores of 3D scaffolds in a perfusion-based bioreactor system, followed by enzymatic digestion for cell retrieval. The 3D-perfusion system supported MSC growth while maintaining cells of the hematopoietic lineage, and thus generated a cellular environment mimicking some features of the bone marrow stroma. As compared to 2D-expansion, sorted CD45- cells derived from 3D-perfusion culture after the same time (3 weeks) or a similar extent of proliferation (7-8 doublings) maintained a 4.3-fold higher clonogenicity and exhibited a superior differentiation capacity towards all typical mesenchymal lineages, with similar immunomodulatory function in vitro. Transcriptomic analysis performed on MSC from 5 donors validated the robustness of the process and indicated a reduced inter-donor variability as well as a significant upregulation of multipotency-related gene clusters following 3D-perfusion as compared to 2D expansion. The described system offers a model to study how factors of a 3D engineered niche may regulate MSC function and, by streamlining conventional labor-intensive processes, is prone to automation and scalability within closed bioreactor systems. Nucleated cells were isolated from 5 fresh human bone marrow aspirates by means of red blood cells lyses buffer and then were seeded into a 3D perfusion bioreactor system using a pure hydroxyapatite 3D scaffold and in conventional Petri dishes (2D). After culture for 19 days, cells from both systems were enzymatically retrieved and sorted using anti-CD45-coated magnetic beads. Total RNA was extracted from CD45- cells, QCed and hybridized to Affymetrix microarrays.
Project description:Neuronal differentiation of PC12 cells in response to NGF is a prototypical model in which signal duration determines a biological response. Sustained ERK activity induced by NGF, as compared to transient activity induced by EGF, is critical to the differentiation of these cells. To characterize the transcriptional program activated preferentially by NGF, we compared global gene expression profiles between cells treated with NGF and EGF for 2-4 hrs, when sustained ERK signaling in response to NGF is most distinct from the transient signal elicited by EGF. This analysis identified 69 genes that were preferentially upregulated in response to NGF. PC12 cells that were starved in low serum media for 24 hrs were treated with NGF (50ng/mL) or EGF (25ng/mL) for 2 or 4 hrs, or left untreated. Total RNA for 3 independent biological replicates was extracted and subjected to Affymetrix Rat Gene 1.0ST Arrays. The 69 genes that were preferentially upregulated by NGF compared to EGF met the following criteria: NGF/No treatment log2> 1, FDR p value< 0.01 and NGF/EGF log2> 0.75, FDR p value< 0.01.
Project description:Purpose: We aimed to determine whether the expression of either wild-type or catalytically inactive LSH, carrying a single point mutation in its ATP binding site (K237Q), could restore the levels and patterns of DNA methylation in Lsh-/- mouse embryonic fibroblasts (MEFs). Methods: Lsh-/- MEFs were transduced with lentiviral particles carrying empty pMSCV vector, pMSCV-LSH-3xFLAG and pMSCV-LSH K/Q-3xFLAG, respectively. Clonal cell lines were generated and tested for LSH expression. Two independent cell lines expressing wild-type LSH and two expressing LSH K/Q were used for further analyses and comparison with wild-type MEFs and Lsh-/- MEFs carrying the empty vector. Genomic DNA was purified from all six cell lines and methylated DNA immunoprecipitation (MeDIP) was performed as described in Weber et al., 2007, Nat Genetics. MeDIP libraries were generated and sequenced on Illumina HiSeq 2000 instrument. Results and conclusions: Our experiments demonstrate that the expression of wild-type LSH, but not the catalytically inactive LSH K/Q, in Lsh-/- MEFs leads to reestablishment of DNA methylation at repetitive sequences and unique developmentally regulated loci in a cell-autonomous manner. Analyses of DNA methylation upon expression of either wild-type or catalytically-inactive LSH in Lsh-/- mouse embryonic fibroblasts.