DREAM/KChIP-3 is a calcium-dependent transcriptional repressor highly expressed in immune cells. Transgenic mice expressing a dominant active DREAM mutant show reduced serum immunoglobulin levels. In vitro assays show that reduced immunoglobulin secretion is an intrinsic defect of transgenic B cells that occurs without impairment in plasma cell differentiation but with an accelerated entry in cell division and an increase in class switch recombination. B cells from DREAM knockout mice did not show any phenotype, due to compensation by endogenous KChIP-2. Expression arrays revealed modified expression of Edem1 and Derlin3, two proteins related to the ER-associated degradation pathway and of Klf9, a cell-cycle regulator. Our results disclose a function of DREAM and KChIP-2 in Ig subclass production in B lymphocytes.
Increased B cell proliferation and reduced Ig production in DREAM transgenic mice.
Specimen part
View SamplesChanges in nuclear Ca2+ homeostasis activate specific gene expression programs and are central to the acquisition and the plastic storage of memories. DREAM /KChIP proteins form heterotetramers that bind DNA and repress transcription in a Ca2+-dependent manner. Single ablation of one member of the DREAM/KChIP family may result in a mild or the absence of phenotype due to partial gene compensation. To study the function of DREAM/KChIP proteins in the brain, we used transgenic mice expressing a Ca2+-insensitive/CREB-independent dominant active mutant DREAM (daDREAM). We show that daDREAM controls the expression of several activity-dependent transcription factors including Npas4, Nr4a1, Mef2C, JunB and c-Fos, as well as the chromatin modifying enzyme Mbd4 and proteins related to actin polymerization like Arc and gelsolin. Thus, directly or through these targets, expression of daDREAM in the forebrain resulted in a complex phenotype characterized by i) impaired learning and memory, ii) loss of recurrent inhibition and enhanced LTP in the dentate gyrus without affecting Kv4-mediated potassium currents, and iii) modified spine density in DG granule neurons. Our results propose DREAM as a master-switch transcription factor regulating several activity-dependent gene expression programs to control synaptic plasticity, learning and memory.
DREAM controls the on/off switch of specific activity-dependent transcription pathways.
Specimen part
View SamplesTumors engender an environment dominated by M2 differentiated tumor macrophages that support tumor invasion, metastases and escape from immune control. In this study, we demonstrate that following radiation therapy of tumors in mice there is an influx of tumor macrophages that polarize towards wound repair and immune suppression.
Expression of NF-κB p50 in tumor stroma limits the control of tumors by radiation therapy.
Specimen part, Treatment, Time
View SamplesProteinases play a pivotal role in wound healing by degrading molecular barriers, regulating cell-matrix interactions and availability of bioactive molecules. Matrix metalloproteinase-13 (MMP-13, collagenase-3) is a wide spectrum proteinase. Its expression and function is linked to the growth and invasion of many epithelial cancers such as squamous cell carcinoma. Moreover, the physiologic expression of MMP-13 is associated e.g. to scarless healing of human fetal skin and adult gingival wounds. While MMP-13 is not found in the normally healing skin wounds in human adults, it is expressed in mouse skin during wound healing. Thus, mouse wound healing models can be utilized for studying the role of MMP-13 in the events of wound healing. As the processes such as the migration and proliferation of keratinocytes, angiogenesis, inflammation and activation of fibroblasts are components of wound repair as well as of cancer, many results received from wound healing studies are also adaptable to cancer research.
MMP-13 regulates growth of wound granulation tissue and modulates gene expression signatures involved in inflammation, proteolysis, and cell viability.
Time
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