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Cell Differentiation Process (cell + differentiation_process)
Selected AbstractsDevelopment of Live Cell Chips to Monitor Cell Differentiation ProcessesENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 1 2008C. Maercker Abstract A big demand exists for high-throughput functional in vitro assays which can measure cellular phenotypes by molecular methods and therefore improve the resources of primary cells for cell therapy, tissue engineering and high-content screenings in drug development. This approach focuses on cellular adhesion which is an important differentiation process during homing of stem cells. Moreover, it is a promising method especially for adherent cells which are not accessible by classical cell sorting methods. The chip design includes a housing with electrodes to measure electric field densities and impedance, respectively. Moreover, specific coatings of the wells permit a perfect growth of the selected cell types. In parallel, protein biomarkers can be followed by light microscopy. So far, experiments have been started to discriminate between different cell densities and cell types. In addition, after stimulating human cardiac fibroblasts and human umbilical vein endothelial cells, concentrations of proteins involved in adhesion had been increased, and proteins were translocated within the cells. In ongoing experiments, different human cell lines and fibroblastoid mesenchymal stem cells isolated from fat tissue, umbilical cord, or bone marrow are tested in the chip. To optimize the adhesion conditions, the surfaces within the vials of the chip were specifically activated. Microscopy was adjusted to be able to measure cellular morphology in parallel. This concept allows to identify the behavior of mesenchymal stem cells, which cannot be described so far by standard biomarkers. In addition, simulation of the homing process of the cells within its stem cell niche in an in vitro assay is a promising setup for large-scale gain-of-function or loss-of-function screenings in functional genomics as well as for generating precursor cells relevant for the therapy of various diseases. [source] Expression of brush border enzymes in response to lead exposure in rat intestineJOURNAL OF APPLIED TOXICOLOGY, Issue 5 2005Priya Kapur Abstract The effect of feeding lead (50 mg kg,1 body weight) daily for 7 days on the development of various brush border enzymes in the intestine has been studied. The activities of brush border sucrase (P < 0.001), lactase (P < 0.001), , -glutamyl transpeptidase (P < 0.05) and leucine aminopeptidase were reduced (P < 0.05), whereas the alkaline phosphatase level was augmented (P < 0.05) in lead fed rats compared with controls. Kinetic studies with sucrase revealed a low Vmax (0.224 in control and 0.160 units mg,1 protein in lead exposed) with no change in Km (12.6,13.5 mm). Western blot analysis for alkaline phosphatase yielded intense staining of enzyme protein in lead fed rats compared with controls, however, the intensity of the antigen signal was reversed for sucrase under these conditions. These findings suggest that ingestion of lead may interfere with the crypt cell differentiation process thus affecting enzyme functions in the rat intestine. Copyright © 2005 John Wiley & Sons, Ltd. [source] RANKL Treatment Releases the Negative Regulation of the Poly(ADP-Ribose) Polymerase-1 on Tcirg1 Gene Expression During Osteoclastogenesis,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 11 2006Guillaume E Beranger Abstract The Tcirg1 gene encodes the osteoclast-specific a3 isoform of the V-ATPase a subunit. Using the mouse osteoclastic model RAW264.7 cells, we studied Tcirg1 gene expression, and we identified PARP-1 as a transcriptional repressor negatively regulated by RANKL during osteoclastogenesis. Introduction: The TCIRG1 gene encodes the a3 isoform of the V-ATPase a subunit, and mutations at this locus account for ,60% of infantile malignant osteopetrosis cases. Using RAW264.7 cells as an osteoclastic differentiation model, we undertook a transcriptional study of the mouse Tcirg1 gene focused on the 4-kb region upstream of the transcription starting point. Materials and Methods: The promoter activity of serial-deletion fragments of the Tcirg1 gene promoter was monitored throughout the RAW264.7 cell differentiation process. We next performed EMSA, UV cross-linking, affinity purification, mass spectrometry analysis, gel supershift, and siRNA transfection experiments to identify the factor(s) interacting with the promoter. Results: The ,3946/+113 region of the mouse Tcirg1 gene displayed a high basal promoter activity, which was enhanced by RANKL treatment of RAW264.7 cells. Constructs deleted up to ,1589 retained this response to RANKL. A deletion up to ,1402 induced a 3-fold enhancement of the basal activity, whereas RANKL response was not affected. EMSA experiments led us to identify within the ,1589/,1402 region, a 10-nucleotide sequence, which bound a nuclear protein present in nondifferentiated RAW264.7 cells. This interaction was lost using nuclear extracts derived from RANKL-treated cells. Affinity purification followed by mass spectrometry analysis and gel supershift assay allowed the identification of poly(ADP-ribose) polymerase-1 (PARP-1) as this transcriptional repressor, whereas Western blot experiments revealed the cleavage of the DNA-binding domain of PARP-1 on RANKL treatment. Finally, both PARP-1 depletion after siRNA transfection and RAW264.7 cell treatment by an inhibitor of PARP-1 activity induced an increase of a3 mRNA expression. Conclusions: We provide evidence that the basal transcription activity of the Tcirg1 gene is negatively regulated by the binding of PARP-1 protein to its promoter region in mouse pre-osteoclast. On RANKL treatment, PARP-1 protein is cleaved and loses its repression effect, allowing an increase of Tcirg1 gene expression that is critical for osteoclast function. [source] Neural differentiation of human embryonic stem cellsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 3 2008Sujoy K. Dhara Abstract Availability of human embryonic stem cells (hESC) has enhanced human neural differentiation research. The derivation of neural progenitor (NP) cells from hESC facilitates the interrogation of human embryonic development through the generation of neuronal subtypes and supporting glial cells. These cells will likely lead to novel drug screening and cell therapy uses. This review will discuss the current status of derivation, maintenance and further differentiation of NP cells with special emphasis on the cellular signaling involved in these processes. The derivation process affects the yield and homogeneity of the NP cells. Then when exposed to the correct environmental signaling cues, NP cells can follow a unique and robust temporal cell differentiation process forming numerous phenotypes. J. Cell. Biochem. 105: 633,640, 2008. © 2008 Wiley-Liss, Inc. [source] Three-dimensional slice cultures from murine fetal gut for investigations of the enteric nervous systemDEVELOPMENTAL DYNAMICS, Issue 1 2007Marco Metzger Abstract Three-dimensional intestinal cultures offer new possibilities for the examination of growth potential, analysis of time specific gene expression, and spatial cellular arrangement of enteric nervous system in an organotypical environment. We present an easy to produce in vitro model of the enteric nervous system for analysis and manipulation of cellular differentiation processes. Slice cultures of murine fetal colon were cultured on membrane inserts for up to 2 weeks without loss of autonomous contractility. After slice preparation, cultured tissue reorganized within the first days in vitro. Afterward, the culture possessed more than 35 cell layers, including high prismatic epithelial cells, smooth muscle cells, glial cells, and neurons analyzed by immunohistochemistry. The contraction frequency of intestinal slice culture could be modulated by the neurotransmitter serotonin and the sodium channel blocker tetrodotoxin. Coculture experiments with cultured neurospheres isolated from enhanced green fluorescent protein (eGFP) transgenic mice demonstrated that differentiating eGFP-positive neurons were integrated into the intestinal tissue culture. This slice culture model of enteric nervous system proved to be useful for studying cell,cell interactions, cellular signaling, and cell differentiation processes in a three-dimensional cell arrangement. Developmental Dynamics 236:128,133, 2007. © 2006 Wiley-Liss, Inc. [source] Notch ligands Delta-like1, Delta-like4 and Jagged1 differentially regulate activation of peripheral T helper cellsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 8 2005Sascha Rutz Abstract The Notch pathway is involved in cell differentiation processes in various organs and at several developmental stages. The importance of Notch for early T lymphocyte development is well established. Recently, Notch has been implicated in directing naive T helper cell differentiation towards the Th1, Th2 or regulatory T cell lineages. However, the molecular events underlying these processes are poorly understood. We show that the Notch ligands Delta-like1, Delta-like4 and Jagged1 differentially affect early T cell activation and proliferation following T cell receptor cross-linking. Delta-like1 and Jagged1 induce a dose-dependent inhibition of early activation markers CD69 and CD25, as well as inhibition of proliferation after anti-CD3 stimulation of purified CD4+ T cells. Similarly, the rapid activation of transcription factors NF-AT, AP-1 and NF-,B is suppressed. In contrast, triggering of Notch by Delta-like4 enhances T cell activation and proliferation. The observed effects are dependent on simultaneous cross-linking of TCR and Notch but independent of ,-secretase-mediated cleavage of Notch. These data suggest direct interference between Notch and early TCR signal transduction events, independent of the classical Notch pathway via release of the Notch intracellular domain. A Notch-mediated alteration of TCR signaling strength may contribute to the recently described modulation of naïve T cell differentiation by Notch ligands. [source] Calcium signalling in bacteriaMOLECULAR MICROBIOLOGY, Issue 2 2004Delfina C. Dominguez Summary Whereas the importance of calcium as a cell regulator is well established in eukaryotes, the role of calcium in prokaryotes is still elusive. Over the past few years, there has been an increased interest in the role of calcium in bacteria. It has been demonstrated that as in eukaryotic organisms, the intracellular calcium concentration in prokaryotes is tightly regulated ranging from 100 to 300 nM. It has been found that calcium ions are involved in the maintenance of cell structure, motility, transport and cell differentiation processes such as sporulation, heterocyst formation and fruiting body development. In addition, a number of calcium-binding proteins have been isolated in several prokaryotic organisms. The characterization of these proteins and the identification of other factors suggest the possibility that calcium signal transduction exists in bacteria. This review presents recent developments of calcium in bacteria as it relates to signal transduction. [source] | |||||||||||||