Detailed information about stage-specific changes in gene expression is crucial for understanding the gene regulatory networks underlying development and the various signal transduction pathways contributing to morphogenesis. Here, we describe the global gene expression dynamics during early murine limb development, when cartilage, tendons, muscle, joints, vasculature, and nerves are specified and the musculoskeletal system of the limbs is established. We used whole-genome microarrays to identify genes with differential expression at 5 stages of limb development (E9.5 to 13.5), during fore-limb and hind-limb patterning. We found that the onset of limb formation is characterized by an up-regulation of transcription factors, which is followed by a massive activation of genes during E10.5 and E11.5 which tampers off at later time points. Among 3520 genes identified as significantly up-regulated in the limb, we find ~30% to be novel, dramatically expanding the repertoire of candidate genes likely to function in the limb. Hierarchical and stage-specific clustering identified expression profiles that correlate with functional programs during limb development and are likely to provide new insights into specific tissue patterning processes. Here we provide for the first time, a comprehensve analysis of developmentally regulated genes during murine limb development, and provide some novel insights into the expression dynamics governing limb morphogenesis.
Global gene expression analysis of murine limb development.
Specimen part
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Low-dose radiation affects cardiac physiology: gene networks and molecular signaling in cardiomyocytes.
Sex, Specimen part
View SamplesIrradiated cell lines exposed to 1-10 Gy
No associated publication
Cell line
View SamplesWe examined molecular responses using transcriptome profiling in isolated left ventricular murine cardiomyocytes to 90 cGy, 1 GeV proton (1H) and 15 cGy, 1 GeV/nucleon (n) iron (56Fe) particles 1, 3, 7, 14 and 28 days after exposure. Unsupervised clustering analysis of gene expression segregated samples according to the radiation (IR) response, and time after exposure with 56Fe-IR showing the greatest level of gene modulation. 1H-IR exposures showed little differential transcript modulation. Network analysis categorized the major differentially expressed genes into cell cycle, oxidative responses and transcriptional regulation functional groups. Transcriptional networks identified key nodes regulating expression. Individual transcription factors were inferred to be active at 1, 3, 7, 14 and 28 days after exposure. Validation of the signal transduction network by protein analysis showed that particle IR clearly regulates a long lived signaling mechanism for p38 MAPK signaling and NFATc4 activation. Electrophoresis mobility shift assays supported the role of additional key transcription factors GATA-4, STAT-3 and NF-B as regulators of the response at specific time points. These data suggest that the molecular response to 56Fe-IR is unique and shows long-lasting gene expression in cardiomyocytes, up to 28 days after exposure. Additionally, proteins involved in signal transduction and transcriptional activation via DNA binding play a role in the response to high charge (Z) and energy (E) particles (HZE). Our study may have implications for NASAs efforts to develop heart disease risk estimates for astronauts safety via identification of specific HZE-IR molecular markers and for patients receiving conventional and particle radiotherapy.
Low-dose radiation affects cardiac physiology: gene networks and molecular signaling in cardiomyocytes.
Sex, Specimen part
View SamplesWe examined molecular responses using transcriptome profiling in isolated left ventricular murine cardiomyocytes to 90 cGy, 1 GeV proton (1H) and 15 cGy, 1 GeV/nucleon (n) proton (56Fe) particles 1, 3, 7, 14 and 28 days after exposure. Unsupervised clustering analysis of gene expression segregated samples according to the radiation (IR) response, and time after exposure with 56Fe-IR showing the greatest level of gene modulation. 1H-IR exposures showed little differential transcript modulation. Network analysis categorized the major differentially expressed genes into cell cycle, oxidative responses and transcriptional regulation functional groups. Transcriptional networks identified key nodes regulating expression. Individual transcription factors were inferred to be active at 1, 3, 7, 14 and 28 days after exposure. Validation of the signal transduction network by protein analysis showed that particle IR clearly regulates a long lived signaling mechanism for p38 MAPK signaling and NFATc4 activation. Electrophoresis mobility shift assays supported the role of additional key transcription factors GATA-4, STAT-3 and NF-B as regulators of the response at specific time points. These data suggest that the molecular response to 56Fe-IR is unique and shows long-lasting gene expression in cardiomyocytes, up to 28 days after exposure. Additionally, proteins involved in signal transduction and transcriptional activation via DNA binding play a role in the response to high charge (Z) and energy (E) particles (HZE). Our study may have implications for NASAs efforts to develop heart disease risk estimates for astronauts safety via identification of specific HZE-IR molecular markers and for patients receiving conventional and particle radiotherapy.
No associated publication
Sex, Specimen part
View SamplesInhibitors of Wnt signaling have been previously shown to be involved in prostate cancer (PC) metastasis; however the role of Sclerostin (Sost) has not yet been explored. Here we show that elevated Wnt signaling derived from Sost deficient osteoblasts (OBSOSTKO) promotes PC invasion while rhSOST has an inhibitory effect. In contrast, rhDKK1 promotes PC elongation and filopodia formation, morphological changes characteristic of an invasive phenotype. Furthermore, rhDKK1 was found to activate canonical Wnt signaling in PC3 cells as quantified by TOPFLASH reporter and b-catenin activity, suggesting that SOST and DKK1 have opposing roles on Wnt signaling in this context. Gene expression analysis of PC3 cells co-cultured with OBs exhibiting varying amounts of Wnt signaling identified CRIM1 as one of the transcripts up-regulated under highly invasive conditions. Following further analysis we found that CRIM1 increases PC3 invasion, complexes with b-catenin, and promotes cell-adhesion, suggesting that elevated Wnt signaling secreted from the bone may promote PC tropism by promoting CRIM1 expression and facilitating cancer cell invasion and adhesion to bone. We concluded that SOST and DKK1 have opposing effects on PC3 cell invasion and that bone-derived Wnt signaling positively contributes to the invasive phenotypes of metastatic cancer cells by activating CRIM1 expression and facilitating PC-OB physical interaction. As such, we investigated the effects of high concentrations of SOST in vivo. We found that PC3-cells overexpressing SOST injected via tail vein did not readily metastasize in NSG xenografts, suggesting that targeting the molecular bone environment may influence bone metastatic outcome in clinical settings.
No associated publication
Cell line, Treatment
View SamplesDynamic interaction between prostate cancer and the bone microenvironment is a major contributor to metastasis of prostate cancer to bone. In this study we utilized an in-vitro co-culture model of PC3 prostate cancer cells and osteoblasts followed by microarray based gene expression profiling to identify previously unrecognized prostate cancer-bone microenvironment interactions. Factors secreted by PC3 cells resulted in the up-regulation of many genes in osteoblasts associated with bone metabolism and cancer metastasis, including Mmp13, Il-6 and Tgfb2, and down-regulation of Wnt inhibitor Sost. To determine whether altered Sost expression in the bone microenvironment has an effect on prostate cancer metastasis, we co-cultured PC3 cells with Sost knockout (SostKO) osteoblasts and wildtype (WT) osteoblasts and identified several genes differentially regulated between PC3-SostKO osteoblast co-cultures and PC3-WT osteoblast co-cultures. Co-culturing PC3 cells with WT osteoblasts up-regulated cancer-associated long noncoding RNA (lncRNA) MALAT1 in PC3 cells. MALAT1 expression was further enhanced when PC3 cells were co-cultured with SostKO osteoblasts and treatment with recombinant Sost down-regulated MALAT1 expression in these cells. Our results suggest that reduced Sost expression in the tumor microenvironment may promote bone metastasis by up-regulating MALAT1 in prostate cancer.
Cancer-Osteoblast Interaction Reduces Sost Expression in Osteoblasts and Up-Regulates lncRNA MALAT1 in Prostate Cancer.
Cell line
View SamplesWNT signaling is critical in most aspects of skeletal development and homeostasis, and antagonists of WNT signaling are emergning as key regulatory proteins with great promise as therapeutic agents for bone disorders. Until recently Sost and its paralog Sostdc1 have been described as growth factors with highly restricted expression in the adult where Sost was assumed 'osteocyte-' and Sostdc1 'kidney-' specific. Here we show that these two proteins emerged throgh ancestral genome duplication and their expression patterns have diverged to span complimentary domains in most organ systems including musculoskeletal, cardiovascular, nervous, digestive, reproductive and respiratory. In the developing limb, Sost and Sostdc1 display dynamic expression patterns with Sost being restricted to the distal ectoderm and Sostdc1 to the proximal ectoderm and the mesenchyme.
Sost and its paralog Sostdc1 coordinate digit number in a Gli3-dependent manner.
Specimen part
View SamplesThe tyrosine kinase ErbB2 positive breast tumors have more aggressive tumor growth, poorer clinical outcome, and more resistance to radiotherapy, chemotherapy and hormone therapy. A humanized anti-ErbB2 monoclonal antibody Herceptin and a small molecules inhibitor Lapatinib were developed and approved by FDA to treat patients with ErbB2 amplification and overexpression. Unfortunately, most ErbB2+ breast cancers do not respond to Herceptin and Lapatinib, and the majority of responders become resistant within 12 months of initial therapy (defined as secondary drug resistance). Such differences in response to Lapatinib treatment is contributed by substantial heterogeneity within ErbB2+ breast cancers. To address this possibility, we carried out transcriptomic analysis of mammary tumors from genetically diverse MMTV-ErbB2 mice. This will help us to have a better understanding of the heterogeneous response to ErbB2 targeted therapy and permit us to design better and more individualized (personalized) treatment strategies for human ErbB2 positive breast cancer.
Unraveling heterogeneous susceptibility and the evolution of breast cancer using a systems biology approach.
Specimen part
View SamplesWe developed a mouse model that captures radiation effects on host biology by transplanting unirradiated Trp53 null mammary tissue to sham or irradiated hosts. Gene expression profiles of tumors that arose in irradiated mice are distinct from those that arose in nave hosts.
Murine microenvironment metaprofiles associate with human cancer etiology and intrinsic subtypes.
Specimen part
View Samples