Project description:Osteogenesis is a highly regulated developmental process and continues during the turnover and repair of mature bone. Runx2, the master regulator of osteoblastogenesis, directs a transcription program essential for bone formation through both genetic and epigenetic mechanisms. While individual Runx2 gene targets have been identified, further insights into the broad spectrum of Runx2 functions required for osteogenesis are needed. By performing genome-wide characterization of Runx2 binding at the three major stages of osteoblast differentiation: proliferation, matrix deposition and mineralization, we identified Runx2-dependent regulatory networks driving bone formation. Using chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-Seq) over the course of these stages, we discovered close to 80,000 significantly enriched regions of Runx2 binding throughout the mouse genome. These binding events exhibited distinct patterns during osteogenesis, and were associated with proximal promoters as well as a large percentage of Runx2 occupancy in non-promoter regions: upstream, introns, exons, transcription termination site (TTS) regions, and intergenic regions. These peaks were partitioned into clusters that are associated with genes in complex biological processes that support bone formation. Using Affymetrix expression profiling of differentiating osteoblasts depleted of Runx2, we identified novel Runx2 targets including Ezh2, a critical epigenetic regulator; Crabp2, a retinoic acid signaling component; Adamts4 and Tnfrsf19, two remodelers of extracellular matrix. We demonstrated by luciferase assays that these novel biological targets are regulated by Runx2 occupancy at non-promoter regions. Our data establish that Runx2 interactions with chromatin across the genome reveal novel genes, pathways and transcriptional mechanisms that contribute to the regulation of osteoblastogenesis. MC3T3-E1 cells were treated with scramble or Runx2 shRNA, then harvested at proliferating stage (day 0) and differentiating stage (day 9). Total RNAs recovered from these cells were hybridization on Affymetrix microarrays. We sought to find new target genes or pathways regulated by Runx2 during osteoblast differentiation. When combined with genome-wide occupancy of Runx2, we expect to gain new insights on how Runx2 controls a transcriptional program essential for osteoblast differentiation.

Project description:The LH surge triggers dramatic transcriptional changes in genes associated with ovulation and luteinization. The present study investigated the spatiotemporal expression of nuclear factor interleukin-3 (NFIL3), a transcriptional regulator of the bZIP transcription factor superfamily, and its potential role in the ovary during the periovulatory period. NFIL3, also known as E4-binding protein 4 or NFIL3/E4BP4, was originally identified as a transcriptional repressor based on its DNA-binding activity at the promoter of the gene encoding the adenovirus E4 protein. Immature female rats were injected with PMSG, treated with hCG, and ovaries or granulosa cells were collected at various times after hCG. Nfil3 mRNA was highly induced both in intact ovaries and granulosa cells after hCG treatment. In situ hybridization demonstrated that Nfil3 mRNA was highly induced in theca-interstitial cells at 4-8 h after hCG, localized to granulosa cells at 12 h, and decreased at 24 h. Over-expression of NFIL3 in granulosa cells inhibited the induction of prostaglandin-endoperoxide synthase 2 (Ptgs2), progesterone receptor (Pgr), epiregulin (Ereg), and amphiregulin (Areg) and down regulated levels of prostaglandin E2. The inhibitory effect on Ptgs2 induction was reversed by NFIL3 siRNA treatment. In theca-interstitial cells the expression of hydroxyprostaglandin dehydrogenase 15-(NAD) (Hpgd) was also inhibited by NFIL3 over-expression. Data from luciferase assays demonstrated that NFIL3 over-expression decreased the induction of the Ptgs2 and Areg promoter activity. EMSA and ChIP analyses indicated that NFIL3 binds to the promoter region containing the DNA binding sites of CREB and C/EBP?. In summary, hCG induction of NFIL3 expression may modulate the process of ovulation and theca-interstitial and granulosa cell differentiation by regulating expression of PTGS2, PGR, AREG, EREG, and HPGD, potentially through interactions with CREB and C/EBP? on their target gene promoters. The granulosa cells were exposed to Ad- NFIL3 or Ad-GFP at a multiplicity of infection (MOI) of 50 pfu/cell. Two hours later, Medium was replaced with fresh Opti-MEM medium. At 24 h after adenovirus exposure, granulosa cells were treated with FSK + PMA for 6 h before collection for RNA isolation using a RNeasy kit according to the manufacturer’s instructions (Qiagen Inc., Valencia, CA). Five micrograms of total RNA were used as a template for cDNA synthesis by the University of Kentucky Microarray Core facility as described previously (47). The Affymetrix Rat 230-2.0 oligonucleotide array sets were hybridized, washed, and scanned using Affymetrix equipment and protocols (Affymetrix, Santa Clara, CA). The DNA microarray assays were performed on total RNA pooled from granulosa cells obtained from 3 separate experiments. The changes observed by DNA microarray analysis were confirmed by real-time PCR for a select subset of genes. Affymetrix GCS 3000 7G scanner was used.

Project description:Osteogenesis is a highly regulated developmental process and continues during the turnover and repair of mature bone. Runx2, the master regulator of osteoblastogenesis, directs a transcription program essential for bone formation through both genetic and epigenetic mechanisms. While individual Runx2 gene targets have been identified, further insights into the broad spectrum of Runx2 functions required for osteogenesis are needed. By performing genome-wide characterization of Runx2 binding at the three major stages of osteoblast differentiation: proliferation, matrix deposition and mineralization, we identified Runx2-dependent regulatory networks driving bone formation. Using chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-Seq) over the course of these stages, we discovered close to 80,000 significantly enriched regions of Runx2 binding throughout the mouse genome. These binding events exhibited distinct patterns during osteogenesis, and were associated with proximal promoters as well as a large percentage of Runx2 occupancy in non-promoter regions: upstream, introns, exons, transcription termination site (TTS) regions, and intergenic regions. These peaks were partitioned into clusters that are associated with genes in complex biological processes that support bone formation. Using Affymetrix expression profiling of differentiating osteoblasts depleted of Runx2, we identified novel Runx2 targets including Ezh2, a critical epigenetic regulator; Crabp2, a retinoic acid signaling component; Adamts4 and Tnfrsf19, two remodelers of extracellular matrix. We demonstrated by luciferase assays that these novel biological targets are regulated by Runx2 occupancy at non-promoter regions. Our data establish that Runx2 interactions withM-BM- chromatin across the genome reveal novel genes, pathways and transcriptional mechanisms that contribute to the regulation of osteoblastogenesis. To identiy the genome-wide occupancy of Runx2, DNA bound by Runx2 at the prolieration, matrix deposition, and mineralization stages were recovered by Runx2 ChIP. Libraries of purified DNA were generated using Illumina SR adapters (Illumina) following manufacturerM-bM-^@M-^Ys manual, and were selected for the inserted fragments of 200 M-BM-1 50 bp, and sequenced 36 bases on an Illumina Genome Analyzer II. Base calls and sequence reads were generated by Illumina CASAVA software (version 1.6, Illumina). Two independent biological repeats of Runx2 ChIP-Seq libraries were prepared for each time point, and two input libraries were prepared with sonicated DNA from day 9 MC3T3-E1 cells. We pooled the reads from two biological replicates for peaking calling using MACS (version 1.4.1) with a stringent p value threshold (p < 1e-10) in contrast to input control, and used these peaks for further bioinformatic analyses. Each sample deposited here contains three files: the sequence file with short reads combined from two biological replicates, a Bed file with peaks called from the pooled short reads, and a Wig file with peak signals.

Project description:Previously, we have identified the RUNX2 gene as hypomethylated and overexpressed in post-chemotherapy (CT) primary cultures derived from epithelial ovarian cancer (EOC) patients, when compared to primary cultures derived from matched primary (prior to CT) tumors. However, we found no differences in the RUNX2 methylation in primary EOC tumors and EOC omental metastases, suggesting that DNA methylation-based epigenetic mechanisms have no impact on RUNX2 expression in advanced (metastatic) stage of the disease. Moreover, RUNX2 displayed significantly higher expression not only in metastatic tissue, but also in high-grade primary tumors and even in low malignant potential tumors. Knockdown of the RUNX2 expression in EOC cells led to sharp decrease of cell proliferation and significantly inhibited EOC cell migration and invasion. Gene expression profiling and consecutive network and pathway analyses confirmed these findings, as various genes and pathways known previously to be implicated in ovarian tumorigenesis, including EOC tumor invasion and metastasis, were found to be downregulated upon RUNX2 suppression, while a number of pro-apoptotic genes and some EOC tumor suppressor genes were induced. Taken together, our data are indicative for a strong oncogenic potential of the RUNX2 gene in EOC progression and suggest that RUNX2 might be a novel EOC therapeutic target. Further studies are needed to more completely elucidate the functional implications of RUNX2 and other members of the RUNX gene family in ovarian tumorigenesis. To better understand the molecular mechanisms of RUNX2 gene action in ovarian cancer cells, we employed the Agilent Whole Human Genome microarrays, containing ~ 44,000 genes to identify global gene expression changes upon RUNX2 suppression in SKOV3 cells. We compared the gene expression of the previously selected clone shRNA- RUNX2-knockdown clone 3 (cl3) against the corresponding control clone. The microarray experiments were performed in duplicates, as two hybridizations were carried out for the RUNX2-suppressing cell clone against the corresponding control, using a fluorescent dye reversal (dye-swap) technique.

Project description:Determining the spatial and temporal expression of genes involved in the ovulatory pathway is critical for the understanding of the role of each estrogen receptor in the modulation of folliculogenesis and ovulation. Estrogen receptor (ER) b is highly expressed in ovarian granulosa cells and mice lacking ERb (bERKO) are subfertile due to inefficient ovulation. Previous work has focused on isolated granulosa cells or cultured follicles and while informative, provides confounding results due to the heterogeneous cell types present including granulosa, theca and oocytes and exposure to in vitro conditions. Herein, we isolated preovulatory granulosa cells from WT and ERb-null mice using laser capture microdissection to examine the genomic transcriptional response downstream of PMSG (mimicking FSH) and PMSG/hCG (mimicking LH) stimulation. This allows for a direct comparison of in vivo granulosa cells at the same stage of development from both WT and ERb-null ovaries. ERb-null granulosa cells showed altered expression of genes known to be regulated by FSH (Akap12 and Runx2) as well as not previously reported (Arnt2 and Pou5f1) in WT granulosa cells. Our analysis also identified 304 genes not previously associated with ERb in granulosa cells. LH responsive genes including Abcb1b and Fam110c show reduced expression in ERb-null granulosa cells; however novel genes including Rassf2 and Megf10 were also identified as being downstream of LH signaling in granulosa cells. Collectively, our data suggests that granulosa cells from ERb-null ovaries may not be appropriately differentiated and are unable to respond properly to gonadotropin stimulation We used microarray to compare the gene expression profiles of wiltype (WT) and Erb-null (bERKO) preovulatory granulosa cells as they respond to either PMSG or PMSG+hCG treatments. Laser microdissection was used to collect a purified population of granulosa cells only from preovulatory follicles. We chose to compre the response to PMSG or PMSG+hCG of granulosa cells collected from either WT and bERKO preovulatory follicles. We chose to collect cells 48h after mice were treated with PMSG to compare the gene expression profile ot preovulatory granulosa cells. We also studied the response of these cells to LH (or hCG) as we collected cells 4h after mice were treated with hCG (peak of transcriptional response to hCG).

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Effect of Runx2 Knockdown by siRNA in granulosa cell cultures.

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