Biomedical subjects

J Delrow

Publications and source records attributed to J Delrow.

6 recordsLinked to original sources

PubMed2006

Interferon regulatory factor-1 regulates reconstituted extracellular matrix (rECM)-mediated apoptosis in human mammary epithelial cells.

Interactions between extracellular matrix (ECM) and mammary epithelial cells are critical for mammary gland homeostasis and apoptotic signaling. Interferon regulatory factor-1 (IRF-1) is a transcriptional regulator that promotes apoptosis during mammary gland involution and p53-independent apoptosis. We have recently shown that rapid cell surface tamoxifen (Tam) signaling promotes apoptosis in normal human mammary epithelial cells that were acutely damaged by expression of human papillomavirus type-16 E6 protein (*HMEC-E6). Apoptosis was mediated by recruitment of CREB-binding protein (CBP) to the gamma-activating sequence (GAS) element of the IRF-1 promoter, induction of IRF-1 and caspase-1/-3 activation. Here, we show that growth factor-depleted, reconstituted ECM (rECM), similar to Tam, promotes apoptosis in *HMEC-E6 cells through induction of IRF-1. Apoptosis was temporally associated with recruitment of CBP to the GAS element of the IRF-1 promoter, induction of IRF-1 expression and caspase-1/-3 activation. Small interfering RNA-mediated suppression of IRF-1 protein expression in *HMEC-E6 cells blocked (1) induction of IRF-1, (2) caspase-1/-3 activation and (3) apoptosis. These observations demonstrate that IRF-1 promotes rECM-mediated apoptosis and provide evidence that both rECM and rapid Tam signaling transcriptionally activate IRF-1 through recruitment of CBP to the IRF-1 GAS promoter complex.

Antineoplastic Agents, Hormonal↗

PubMed2006

Genomic instability during Myc-induced lymphomagenesis in the bursa of Fabricius.

Retroviral vector-mediated overexpression of c-myc in embryonic bursal precursors induces multi-staged tumorigenesis beginning with preneoplastic-transformed follicles (TF) and progressing to clonal metastatic B-cell lymphomas. Using a 13K chicken cDNA microarray, specifically enriched for chicken immune system expressed sequence tagged (ESTs), we carried out array-based comparative genomic hybridization (array-CGH) and detected significant DNA copy number change at many loci on most or all chromosomes in both early TF and end-stage lymphomas. Formation of long palindromes, through breakage-fusion-bridge cycles, is thought to play an early role in gene amplification. Employing genome-wide analysis of palindrome formation (GAPF), we detected extensive palindrome formation in early TF and end-stage lymphomas. The population of loci showing amplification by array-CGH was enriched for palindromes detected by GAPF providing strong evidence for genetic instability early in Myc-induced tumorigenesis and further support for the role of palindromes in gene amplification. Comparing gene copy number change and RNA expression changes profiled on the same cDNA array, we detected very little consistent contribution of gene copy number change to RNA expression changes. Palindromic loci in TF and tumors, however, were expressed, many at high levels, suggesting an abundance of RNA species with long double-stranded segments generated during tumorigenesis.

Animals↗

PubMed2001

Project normal: defining normal variance in mouse gene expression.

The mouse has become an indispensable and versatile model organism for the study of development, genetics, behavior, and disease. The application of comprehensive gene expression profiling technologies to compare normal and diseased tissues or to assess molecular alterations resulting from various experimental interventions has the potential to provide highly detailed qualitative and quantitative descriptions of these processes. Ideally, to interpret experimental data, the magnitude and diversity of gene expression for the system under study should be well characterized, yet little is known about the normal variation of mouse gene expression in vivo. To assess natural differences in murine gene expression, we used a 5406-clone spotted cDNA microarray to quantitate transcript levels in the kidney, liver, and testis from each of 6 normal male C57BL6 mice. We used ANOVA to compare the variance across the six mice to the variance among four replicate experiments performed for each mouse tissue. For the 6 kidney samples, 102 of 3,088 genes (3.3%) exhibited a statistically significant mouse variance at a level of 0.05. In the testis, 62 of 3,252 genes (1.9%) showed statistically significant variance, and in the liver, there were 21 of 2,514 (0.8%) genes with significantly variable expression. Immune-modulated, stress-induced, and hormonally regulated genes were highly represented among the transcripts that were most variable. The expression levels of several genes varied significantly in more than one tissue. These studies help to define the baseline level of variability in mouse gene expression and emphasize the importance of replicate microarray experiments.

Animals↗

PubMed2001

Analysis of gene expression during myc oncogene-induced lymphomagenesis in the bursa of Fabricius.

The transcriptional effects of deregulated myc gene overexpression are implicated in tumorigenesis in a spectrum of experimental and naturally occurring neoplasms. In follicles of the chicken bursa of Fabricius, myc induction of B-cell neoplasia requires a target cell population present during early bursal development and progresses through preneoplastic transformed follicles to metastatic lymphomas. We developed a chicken immune system cDNA microarray to analyze broad changes in gene expression that occur during normal embryonic B-cell development and during myc-induced neoplastic transformation in the bursa. The number of mRNAs showing at least 3-fold change was greater during myc-induced lymphomagenesis than during normal development, and hierarchical cluster analysis of expression patterns revealed that levels of several hundred mRNAs varied in concert with levels of myc overexpression. A set of 41 mRNAs were most consistently elevated in myc-overexpressing preneoplastic and neoplastic cells, most involved in processes thought to be subject to regulation by Myc. The mRNAs for another cluster of genes were overexpressed in neoplasia independent of myc expression level, including a small subset with the expression signature of embryonic bursal lymphocytes. Overexpression of myc, and some of the genes overexpressed with myc, may be important for generation of preneoplastic transformed follicles. However, expression profiles of late metastatic tumors showed a large variation in concert with myc expression levels, and some showed minimal myc overexpression. Therefore, high-level myc overexpression may be more important in the early induction of these lymphomas than in maintenance of late-stage metastases.

Animals↗

PubMed2001

Chromatin profiling using targeted DNA adenine methyltransferase.

Chromatin is the highly complex structure consisting of DNA and hundreds of associated proteins. Most chromatin proteins exert their regulatory and structural functions by binding to specific chromosomal loci. Knowledge of the identity of these in vivo target loci is essential for the understanding of the functions and mechanisms of action of chromatin proteins. We report here large-scale mapping of in vivo binding sites of chromatin proteins, using a novel approach based on a combination of targeted DNA methylation and microarray technology. We show that three distinct chromatin proteins in Drosophila melanogaster cells each associate with specific sets of genes. HP1 binds predominantly to pericentric genes and transposable elements. GAGA factor associates with euchromatic genes that are enriched in (GA)n motifs. A Drosophila homolog of Saccharomyces cerevisiae Sir2p is associated with several active genes and is excluded from heterochromatin. High-resolution, genome-wide maps of target loci of chromatin proteins ('chromatin profiles') provide new insights into chromatin structure and gene regulation.

Animals↗

PubMed2001

Widespread collaboration of Isw2 and Sin3-Rpd3 chromatin remodeling complexes in transcriptional repression.

The yeast Isw2 chromatin remodeling complex functions in parallel with the Sin3-Rpd3 histone deacetylase complex to repress early meiotic genes upon recruitment by Ume6p. For many of these genes, the effect of an isw2 mutation is partially masked by a functional Sin3-Rpd3 complex. To identify the full range of genes repressed or activated by these factors and uncover hidden targets of Isw2-dependent regulation, we performed full genome expression analyses using cDNA microarrays. We find that the Isw2 complex functions mainly in repression of transcription in a parallel pathway with the Sin3-Rpd3 complex. In addition to Ume6 target genes, we find that many Ume6-independent genes are derepressed in mutants lacking functional Isw2 and Sin3-Rpd3 complexes. Conversely, we find that ume6 mutants, but not isw2 sin3 or isw2 rpd3 double mutants, have reduced fidelity of mitotic chromosome segregation, suggesting that one or more functions of Ume6p are independent of Sin3-Rpd3 and Isw2 complexes. Chromatin structure analyses of two nonmeiotic genes reveals increased DNase I sensitivity within their regulatory regions in an isw2 mutant, as seen previously for one meiotic locus. These data suggest that the Isw2 complex functions at Ume6-dependent and -independent loci to create DNase I-inaccessible chromatin structure by regulating the positioning or placement of nucleosomes.

Adenosine Triphosphatases↗