Project description:To investigate the role of FOS/AP-1 in early OnF reprogramming, we blocked its activity during tumor intiation by overexpressing a dominant negative form of FOS.
Project description:To identify AP-1 regulated genes in KYAE-1 and OE19 oesophageal adenocarcinoma cells we induced expression of dominant negative (acidic) FOS to inhibit AP-1 activity and then performed RNA-seq. Acidic FOS (aFOS, J Biol Chem. 1997 Jul 25;272(30):18586-94. doi: 10.1074/jbc.272.30.18586) was expressed from the pINDUCER20 vector.
Project description:FOS, a subunit of the activator protein-1 (AP-1) transcription factor, has been implicated in various cellular changes. In the human ovary, the expression of FOS and its heterodimeric binding partners JUN, JUNB, and JUND increases in periovulatory follicles. However, the specific role of the FOS/AP-1 remains elusive. The present study determined the regulatory mechanisms driving the expression of FOS and its partners and functions of the FOS/AP-1 using primary human granulosa/lutein cells (hGLC). hCG induced a biphasic increase in the expression of FOS, peaking at 1-3h and 12h. The levels of JUN proteins were also increased by hCG, with varying expression patterns. Co-immunoprecipitation analyses revealed that FOS is present as heterodimers with all JUN proteins. hCG immediately activated PKA and p42/44MAPK signaling pathways, and inhibitors for these pathways abolished hCG-induced increases in the levels of FOS, JUN, and JUNB. To identify the genes regulated by FOS, high throughput RNA sequencing was performed using hGLC treated with hCG ± T-5224 (FOS inhibitor). Sequencing data analysis revealed that FOS inhibition affects the expression of numerous genes, including a cluster of genes involved in the periovulatory process such as matrix remodeling, prostaglandin synthesis, glycolysis/gluconeogenesis, and cholesterol biosynthesis. qPCR analysis verified hCG-induced, T-5224-regulated expression of a selection of these genes. Consistently, T-5224 attenuated hCG-induced increases in metabolic activities and cholesterol levels. This study unveiled potential downstream target genes of and a role for the FOS/AP-1 in granulosa cell metabolic changes and cholesterol biosynthesis in human periovulatory follicles.
Project description:In our investigations of the molecular pathways of prostate tumorigenesis in Nkx3.1; Pten mutant mice using gene expression profiling, we now find that the AP-1 transcription factors, c-Jun and c-Fos, are significantly up-regulated during cancer progression. Forced expression of c-Fos and c-Jun in prostate cancer cells results in increased tumorigenicity, activation of Erk MAP kinase, and enhanced survival in the absence of androgens, which are hallmarks of disease progression. In humans, Jun and Fos proteins are significantly up-regulated during prostate cancer progression and significantly correlated with activation of Erk MAP kinase. Most notably, expression of Jun is associated with disease recurrence independent of other currently used prognostic indicators. These analyses reveal a hitherto unappreciated role for AP-1 transcription factors in prostate cancer progression vis-à-vis Erk MAP kinase signaling, as well as the identification of a novel marker of disease recurrence, namely c-Jun. Keywords: Stages of Prostate Cancer
Project description:Proto-oncogene c-Fos is a leucine-zipper containing transcription factor which has a DNA binding domain and a transactivation domain. Fos dimerizes with another transcription factor Jun to form AP1 transcription factor. The AP-1 complex has been implicated in transformation and progression of cancer. For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf Map binding sites of transcription factor Fos in the genome of K562 cells. The K562 input data has been deposited in GEO as GSM325934.
Project description:Estrogen receptor alpha (ERalpha) is a ligand-dependent transcription factor that plays an important role in breast cancer. Estrogen-dependent gene regulation by ERalpha can be mediated by interaction with other DNA-binding proteins, such as activator protein-1 (AP-1). The nature of such interactions in mediating the estrogen response in breast cancer cells remains unclear. Here we show that knockdown of c-Fos, a component of the transcription factor AP-1, attenuates the expression of 37% of all estrogen-regulated genes, suggesting that AP-1 is a fundamental factor for ERalpha-mediated transcription. Additionally, knockdown of c-Fos affected the expression of a number of genes that were not regulated by estrogen. Pathway analysis reveals that silencing of c-Fos downregulates an E2F1-dependent pro-proliferative gene network. Thus, modulation of the E2F1 pathway by c-Fos represents a novel mechanism by which c-Fos enhances breast cancer cell proliferation. Furthermore, we show that c-Fos and ERalpha can cooperate in regulating E2F1 gene expression by binding to regulatory elements in the E2F1 promoter. To start to dissect the molecular details of the cross-talk between AP-1 and estrogen signaling, we identify a novel ERalpha/AP-1 target, PKIB (cAMP-dependent protein kinase inhibitor-beta), which is overexpressed in ERalpha-positive breast cancer tissues. Knockdown of PKIB by siRNA results in drastic growth suppression of breast cancer cells. Collectively, our findings support AP-1 as a critical factor that governs estrogen-dependent gene expression and breast cancer proliferation programs. MCF-7 cells were transfected with a control siRNA or with the pool of siRNAs targeting c-Fos for 72 h and were then treated with vehicle or E2 for 24 h, and global gene expression profiles were assessed. Three or four biological replicates were used for each group.
Project description:c-Fos, a member of the stress-activated Activator Protein 1 (AP-1) transcription factor family, is expressed in human hepatocellular cancer (HCC). Using genetically engineered mouse models (GEMMs) we show that hepatocyte-specific expression of c-Fos leads to a proliferative, de-differentiated phenotype, whereas hepatocyte-specific deletion of c-Fos protects against diethylnitrosamine (DEN)-induced liver cancer. Furthermore, c-Fos-expressing livers resemble human HCCs based on expression profiles. In the present RNA seq, we intend to analyze the transcriptomic profile of livers at 2 and 4 mo hepatocyte-specific c-Fos expression compared to the corresponding age-matched control mice. Moreover, we analyzed livers of mice with hepatocyte-specific deletion c-Fos at 48h after DEN treatment compared to identically treated control mice.
Project description:Embryonic blood cell development occurs via well-defined developmental stages which are recapitulated in vitro by differentiation of embryonic stem cells. This process is tightly regulated by the interaction of tissue- specific and ubiquitous transcription factors with the chromatin landscape in response to outside signals. We previously identified binding motifs for the commonly expressed AP-1 transcription factor family in open chromatin regions specific for early stages of blood specification and thus aimed to study the role of AP-1 for hemangioblast differentiation. Here we show that FOS and JUN together bind to and activate a core set of vascular genes in the hemogenic endothelium and that upon global inhibition of AP-1 by expression of a dominant negative FOS peptide the balance between endothelial and hematopoietic fate is shifted towards blood. Moreover, we demonstrate that in the hemogenic endothelium AP-1 is required for de novo binding of TEAD4, a transcription factor connected to Hippo signaling, to vascular genes. Notably, after the endothelial-to-hematopoietic transition TEAD4 binding is no longer persisting. These findings provide novel mechanistic insights into vascular and hematopoietic development.
Project description:Proto-oncogene c-Fos is a leucine-zipper containing transcription factor which has a DNA binding domain and a transactivation domain. Fos dimerizes with another transcription factor Jun to form AP1 transcription factor. The AP-1 complex has been implicated in transformation and progression of cancer. For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf