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Jared M Ordway

Publications and source records attributed to Jared M Ordway.

6 recordsLinked to original sources
PubMed2005

A transcriptome map of cellular transformation by the fos oncogene.

BACKGROUND: The c-fos gene was originally identified as the cellular homolog of the oncogene v-fos carried by the Finkel-Biskis-Jenkins and Finkel-Biskis-Reilly murine osteogenic sarcoma retroviruses. Sustained expression of fos is sufficient to induce cellular transformation in vitro and tumorigenesis in vivo. Fos functions as a component of the AP-1 transcription factor complex to regulate gene transcription and several differentially expressed genes have been identified in cells transformed by fos. We have extended these studies by constructing a cellular system for conditional transformation by v-fos. Using Affymetrix-based DNA microarray technology, we analyzed transcriptional changes over the course of transformation and reversion in an inducible v-fos system. RESULTS: Microarray analyses of temporal gene expression during the process of v-fos mediated cellular transformation and morphological reversion revealed a remarkably dynamic transcriptome. Of the more than 8000 genes analyzed in this study, 3766 genes were categorized into 18 gene-expression patterns by using self-organizing map analysis. By combining the analysis of gene expression profiles in stably transformed cells with the analysis of sequential expression patterns during conditional transformation, we identified a relatively small cohort of genes implicated in v-fos mediated cellular transformation. CONCLUSION: This approach defines a general conditional cell transformation system that can be used to study the endogenous transcription regulatory mechanisms involved in transformation and tumorigenesis. In addition, this study is the first reported analysis of dynamic changes in gene expression throughout experimentally controlled morphological transformation mediated by v-fos.

Cell Line↗
PubMed2004

Transcription repression in oncogenic transformation: common targets of epigenetic repression in cells transformed by Fos, Ras or Dnmt1.

Fos and Ras function in both dependent and independent signal transduction pathways, and sustained activity of either oncogene is sufficient to induce cell transformation and tumorigenesis. Increased DNA (cytosine-5) methyltransferse (Dnmt1) activity is involved in the mechanism of transformation by both oncogenes, suggesting that inappropriate epigenetic transcription regulation may be a common route of oncogenesis, and that cell transformation may model aspects of the epigenetic deregulation that often occurs in tumors. Here, we have taken a microarray-based gene expression approach to identify differentially expressed genes in cells transformed by c-fos, v-fos, ras or Dnmt1. The cohort of genes differentially expressed in all four transformation systems includes an over-representation of repressed genes, many of which have been functionally implicated in the suppression of transformation or tumorigenesis. Furthermore, we identified four potential tumor suppressor genes subject to epigenetic transcriptional repression in transformed cells. The results emphasize the role of transcription repression in oncogenesis, and they provide insights into the potential common epigenetic mechanisms impacting cell transformation.

Animals↗
PubMed2003

Hprt(CAG)146 mice: age of onset of behavioral abnormalities, time course of neuronal intranuclear inclusion accumulation, neurotransmitter marker alterations, mitochondrial function markers, and susceptibility to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.

We reported previously a model of polyglutamine repeat disorders with insertion of 146 CAG repeats into the murine hypoxanthine phosphoribosyl transferase locus (Hprt(CAG)146; Ordway et al. [1997] Cell 91:753-763), which does not normally contain polyglutamine repeats. These mice develop an adult-onset neurologic phenotype of incoordination, involuntary limb clasping, seizures, and premature death. Histologic analysis demonstrates widespread ubiquinated neuronal intranuclear inclusions (NIIs). We now report characterization of the age of onset of behavioral abnormalities, correlated with the time course of occurrence of NIIs in several brain regions, and the occurrence of NIIs in non-neuronal tissues. Onset of behavioral abnormalities occurred at approximately 22 weeks of age. There was variable time course of expression of NIIs in several brain regions. Assessment of several non-neuronal tissues revealed nuclear inclusions in hepatocytes and choroid plexus epithelium. Gamma-aminobutyric acid (GABA)/benzodiazepine receptors, dopamine D1-like and D2-like receptors, and type 2 vesicular monoamine transporter (VMAT2) binding sites were assayed before and after the onset of behavioral abnormalities. GABA/benzodiazepine receptors were unchanged either before or after the onset of behavioral abnormalities in any region analyzed, whereas striatal D1-like and D2-like receptors were diminished after but not before the onset of symptoms. Dorsal striatal VMAT2 binding sites were decreased before the onset of behavioral changes. Mitochondrial electron transport chain components were assayed with histochemical methods before and after the onset of behavioral changes. There was no change in behaviorally presymptomatic or symptomatic animals. Hprt(CAG)146 mice did not exhibit increased susceptibility to the mitochondrial toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Hprt(CAG)146 mice are a useful model for studying polyglutamine repeat disorders.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2003

Cysteine 64 of Ref-1 is not essential for redox regulation of AP-1 DNA binding.

Ref-1 participates in DNA repair as well as in redox regulation of transcription factor function. The redox function of Ref-1 involves reduction of oxidized cysteine residues within the DNA binding domains of several transcription factors, including Fos and Jun. Reduction of these residues is required for DNA binding, providing a redox-dependent mechanism for regulation of target gene expression. Previous in vitro studies implicated cysteine 65 of human Ref-1 (cysteine 64 of mouse Ref-1) as the redox catalytic site. We analyzed the in vivo role of cysteine 64 in redox regulation of AP-1 activity by introducing a cysteine-to-alanine point mutation into the endogenous mouse Ref-1 gene (ref-1(C64A)). Unlike Ref-1 null mice, which die very early in embryonic development, homozygous ref-1(C64A) mice are viable, they survive to normal life expectancy, and they display no overt abnormal phenotype. Although Ref-1 provides the major AP-1-reducing activity in murine cells, ref-1(C64A) cells retain normal levels of endogenous AP-1 DNA binding activity in vivo as well as normal Fos- and Jun-reducing activity in vitro. These results demonstrate that Ref-1 cysteine 64/65 is not required for redox regulation of AP-1 DNA binding in vivo, and they challenge previous hypotheses regarding the mechanism by which Ref-1 regulates the redox-dependent activity of specific transcription factors.

Animals↗