The development of the epidermis, a stratified squamous epithelium, is dependent on the regulated differentiation of keratinocytes. Differentiation begins with the initiation of stratification, a process tightly controlled through proper gene expression. AP-2 is expressed in skin and previous research suggested a pathway where p63 gene induction results in increased expression of AP-2 which in turn is responsible for induction of K14. This study uses a conditional gene ablation model to further explore the role of AP-2 in skin development. Mice deficient for AP-2 exhibited delayed expression of p63, K14, and K1, key genes required for development and differentiation of the epidermis. In addition, microarray analysis of E16.5 skin revealed delayed expression of additional late epidermal differentiation genes: filaggrin, repetin and secreted Ly6/Plaur domain containing 1, in mutant mice. The genetic delay in skin development was further confirmed by a functional delay in the formation of an epidermal barrier. These results document an important role for AP-2 in skin development, and reveal the existence of regulatory factors that can compensate for AP-2 in its absence.
Disruption of epidermal specific gene expression and delayed skin development in AP-2 gamma mutant mice.
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View Samples5,6-Dimethylxanthenone-4-acetic acid (DMXAA), a tumor vascular disrupting agent, is shown here to have substantial activity as a single agent against human A375 melanoma xenografts in nude mice (94 % hemorrhagic necrosis after 24 h, and 26 days growth delay following single dose at 25 mg/kg). CD45+ cells in tumor tissue increased 5-fold over the first 3 days after treatment, which was due largely to an influx of CD11b+ Ly6G+ neutrophils. Using murine and human multiplex cytokine assays to dissect the cytokines produced by host stromal cells or by the melanoma cells, it was shown that both the stromal cells and the A375 melanoma cells produced cytokines capable of attracting neutrophils into the tumor. The same xenografts were also analyzed using human and mouse Affymetrix microarrays to separately identify tumor cell-specific (human) and stromal cell-specific (mouse) gene expression changes. DMXAA induced numerous stromal cytokine mRNAs, including IP-10, IL-6, MIP-1/, MIP-2, KC, RANTES, MIG, MCP-1 and IL-1, many of which were also elevated at the protein level. Numerous human cytokine mRNAs were also induced including MCP-1, IL-8, GRO, VEGF, GM-CSF and IL-6, which again was in line with our protein data. Pathway analysis indicated that significant numbers of the stromal mRNAs induced by DMXAA are regulated downstream of TNF-, interferon- and NFB. Our results suggest that DMXAA may have utility in combination therapy for human melanoma through the activation of pro-inflammatory signalling pathways and cytokine expression from both stromal and tumor cells, leading to haemorrhagic necrosis, neutrophil influx and growth inhibition.
Dissection of stromal and cancer cell-derived signals in melanoma xenografts before and after treatment with DMXAA.
Specimen part, Cell line
View SamplesChromatin architectural protein NSBP1/HMGN5 belongs to the family of HMGN proteins which specifically interact with nucleosomes via Nucleosome Binding Domain, unfold chromatin and affect transcription. Mouse NSBP1 is a new and uncharacterized member of HMGN protein family. NSBP1 is a nuclear protein which is localized to euchromatin, binds to linker histone H1 and unfolds chromatin.
The interaction of NSBP1/HMGN5 with nucleosomes in euchromatin counteracts linker histone-mediated chromatin compaction and modulates transcription.
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View SamplesThe cytosolic protein Sharpin is as a component of the linear ubiquitin chain assembly complex (LUBAC), which regulates NF-B signaling in response to specific ligands. Its inactivating mutation in Cpdm (chronic proliferative dermatitis mutation) mice causes multi-organ inflammation, yet this phenotype is not transferable into wildtype mice by hematopoietic stem cell transfer. Recent evidence demonstrated that Cpdm mice additionally display low bone mass, but the cellular and molecular causes of this phenotype remained to be established. Here we have applied non-decalcified histology together with cellular and dynamic histomorphometry to perform a thorough skeletal phenotyping of Cpdm mice. We show that Cpdm mice display trabecular and cortical osteopenia, solely explained by impaired bone formation, whereas osteoclastogenesis is unaffected. We additionally found that Cpdm mice display a severe disturbance of articular cartilage integrity in the absence of joint inflammation, supporting the concept that Sharpin-deficiency affects mesenchymal cell differentiation. Consistently, Cpdm mesenchymal cells displayed reduced osteogenic capacitiy ex vivo, yet this defect was not associated with impaired NF-B signaling. A molecular comparison of wildtype and Cpdm bone marrow cell populations further revealed that Cpdm mesenchymal cells produce higher levels of Cxcl5 and lower levels of IL1ra. Collectively, our data demonstrate that skeletal defects of Cpdm mice are not caused by chronic inflammation, but that Sharpin is as a critical regulator of mesenchymal cell differentiation and gene expression. They additionally provide an alternative molecular explanation for the inflammatory phenotype of Cpdm mice and the absence of disease transfer by hematopoetic stem cell transplantation.
Sharpin Controls Osteogenic Differentiation of Mesenchymal Bone Marrow Cells.
Specimen part
View SamplesRb and E2F are thought to play antagonistic roles in celll proliferation. However, this model is based mostly from in vitro cell culture systems. We used small intestines to test this model in vivo.
E2f1-3 switch from activators in progenitor cells to repressors in differentiating cells.
Age, Specimen part
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