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Different Cell Populations (different + cell_population)
Selected AbstractsMAP kinase activation in avian cardiovascular developmentDEVELOPMENTAL DYNAMICS, Issue 4 2004Christine M. Liberatore Abstract Signaling pathways mediated by receptor tyrosine kinases (RTK) and mitogen-activated protein kinase (MAPK) activation have multiple functions in the developing cardiovascular system. The localization of diphosphorylated extracellular signal regulated kinase (dp-ERK) was monitored as an indicator of MAPK activation in the forming heart and vasculature of avian embryos. Sustained dp-ERK expression was observed in vascular endothelial cells of embryonic and extraembryonic origins. Although dp-ERK was not detected during early cardiac lineage induction, MAPK activation was observed in the epicardial, endocardial, and myocardial compartments during heart chamber formation. Endocardial expression of dp-ERK in the valve primordia and heart chambers may reflect differential cell growth associated with RTK signaling in the heart. dp-ERK localization in the epicardium, subepicardial fibroblasts, myocardial fibroblasts, and coronary vessels is consistent with MAPK activation in epicardial-derived cell lineages. The complex temporal,spatial regulation of dp-ERK in the heart supports diverse regulatory functions for RTK signaling in different cell populations, including the endocardium, myocardium, and epicardial-derived cells during cardiac organogenesis. Developmental Dynamics 230:773,780, 2004. © 2004 Wiley-Liss, Inc. [source] AQP4 expression in striatal primary cultures is regulated by dopamine , implications for proliferation of astrocytesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2008Eva Küppers Abstract Proliferation of astrocytes plays an essential role during ontogeny and in the adult brain, where it occurs following trauma and in inflammation and neurodegenerative diseases as well as in normal, healthy mammals. The cellular mechanisms underlying glial proliferation remain poorly understood. As dopamine is known to modulate proliferation in different cell populations, we investigated the effects of dopamine on the proliferation of striatal astrocytes in vitro. We found that dopamine reduced proliferation. As proliferation involves, among other things, a change in cell volume, which normally comes with water movement across the membrane, water channels might represent a molecular target of the dopamine effect. Therefore we studied the effect of dopamine on aquaporin 4 (AQP4) expression, the main aquaporin subtype expressed in glial cells, and observed a down-regulation of the AQP4-M23 isoform. This down-regulation was the cause of the dopamine-induced decrease in proliferation as knockdown of AQP4 using siRNA techniques mimicked the effects of dopamine on proliferation. Furthermore, stimulation of glial proliferation by basic fibroblast growth factor was also abolished by knocking down AQP4. In addition, blocking of AQP4 with 10 ,m tetraethylammonium inhibited osmotically induced cell swelling and stimulation of glial cell proliferation by basic fibroblast growth factor. These results demonstrate a clear-cut involvement of AQP4 in the regulation of proliferation and implicate that modulation of AQP4 could be used therapeutically in the treatment of neurodegenerative diseases as well as in the regulation of reactive astrogliosis by preventing or reducing the glia scar formation, thus improving regeneration following ischemia or other trauma. [source] TNF receptor type 1 regulates RANK ligand expression by stromal cells and modulates osteoclastogenesisJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 5 2004Yousef Abu-Amer Abstract TNF, is a major osteoclastogenic cytokine and a primary mediator of inflammatory osteoclastogenesis. We have previously shown that this cytokine directly targets osteoclasts and their precursors and that deletion of its type-1 receptor (TNFr1) lessens osteoclastogenesis and impacts RANK signaling molecules. Osteoclastogenesis is primarily a RANK/RANKL-dependent event and occurs in an environment governed by both hematopoietic and mesenchymal compartments. Thus, we reasoned that TNF/TNFr1 may regulate RANKL and possibly RANK expression by stromal cells and osteoclast precursors (OCPs), respectively. RT-PCR experiments reveal that levels of RANKL mRNA in WT stromal cells are increased following treatment with 1,25-VD3 compared to low levels in TNFr1-null cells. Expression levels of OPG, the RANKL decoy protein, were largely unchanged, thus supporting a RANKL/OPG positive ratio favoring WT cells. RANK protein expression by OCPs was lower in TNFr1-null cells despite only subtle differences in mRNA expression in both cell types. Mix and match experiments of different cell populations from the two mice phenotypes show that WT stromal cells significantly, but not entirely, restore osteoclastogenesis by TNFr1-null OCPs. Similar results were obtained when the latter cells were cultured in the presence of exogenous RANKL. Altogether, these findings indicate that in the absence of TNFr1 both cell compartments are impaired. This was further confirmed by gain of function experiments using TNFr1- null cultures of both cell types at which exogenous TNFr1 cDNA was virally expressed. Thus, restoration of TNFr1 expression in OCPs and stromal cells was sufficient to reinstate osteoclastogenesis and provides direct evidence that TNFr1 integrity is required for optimal RANK-mediated osteoclastogenesis. © 2004 Wiley-Liss, Inc. [source] MR tracking of transplanted cells with "positive contrast" using manganese oxide nanoparticlesMAGNETIC RESONANCE IN MEDICINE, Issue 1 2008Assaf A. Gilad Abstract Rat glioma cells were labeled using electroporation with either manganese oxide (MnO) or superparamagnetic iron oxide (SPIO) nanoparticles. The viability and proliferation of SPIO-labeled cells (1.9 mg Fe/ml) or cells electroporated with a low dose of MnO (100 ,g Mn/ml) was not significantly different from unlabeled cells; a higher MnO dose (785 ,g Mn/ml) was found to be toxic. The cellular ion content was 0.1,0.3 pg Mn/cell and 4.4 pg Fe/cell, respectively, with cellular relaxivities of 2.5,4.8 s,1 (R1) and 45,84 s,1 (R2) for MnO-labeled cells. Labeled cells (SPIO and low-dose MnO) were each transplanted in contralateral brain hemispheres of rats and imaged in vivo at 9.4T. While SPIO-labeled cells produced a strong "negative contrast" due to the increase in R2, MnO-labeled cells produced "positive contrast" with an increased R1. Simultaneous imaging of both transplants with opposite contrast offers a method for MR "double labeling" of different cell populations. Magn Reson Med 60:1,7, 2008. © 2008 Wiley-Liss, Inc. [source] Origins and migratory routes of murine Cajal-Retzius cellsTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 3 2007Fernando García-Moreno Abstract The first layer that appears in the cortical neuroepithelium, the preplate, forms in the upper part of the cortex immediately below the pial surface. In mice, this layer exists between embryonic days (E) 10 and 13, and it hosts different cell populations. Here, we have studied the first cell population generated in the preplate, the Cajal-Retzius cells. There is considerable confusion regarding these cells with respect to both their site of generation and the migratory routes that they follow. This perhaps is due largely to the different opinions that exist regarding their characterization. We have studied the site of origin of these cells, their migratory routes, and the molecular markers that may distinguish them by injecting tracers into early embryos, culturing them in toto for 24 hours, and then performing immunohistochemistry. We found that the Cajal-Retzius cells are most likely generated in the cortical hem by comparing with other cortical or extracortical origins. These cells are generated mainly at E10 and E11, and they subsequently migrate tangentially to cover the whole cortical mantle in 24 hours. From their site of origin in the medial wall of the telencephalon, they spread in a caudorostral direction, following an oblique migratory path toward the lateral part of the neuroepithelium. Prior to the splitting of the preplate, a percentage of the Cajal-Retzius cells that can be distinguished by the expression of reelin do not contain calretinin. Furthermore, there were no early-migrating neurons that expressed calbindin. J. Comp. Neurol. 500:419,432, 2007. © 2006 Wiley-Liss, Inc. [source] Genome-Wide Transcription Profile of Endothelial Cells After Cardiac Transplantation in the RatAMERICAN JOURNAL OF TRANSPLANTATION, Issue 7 2010B. Mikalsen Transcriptome analyses of organ transplants have until now usually focused on whole tissue samples containing activation profiles from different cell populations. Here, we enriched endothelial cells from rat cardiac allografts and isografts, establishing their activation profile at baseline and on days 2, 3 and 4 after transplantation. Modulated transcripts were assigned to three categories based on their regulation profile in allografts and isografts. Categories A and B contained the majority of transcripts and showed similar regulation in both graft types, appearing to represent responses to surgical trauma. By contrast, category C contained transcripts that were partly allograft-specific and to a large extent associated with interferon-,-responsiveness. Several transcripts were verified by immunohistochemical analysis of graft lesions, among them the matricellular protein periostin, which was one of the most highly upregulated transcripts but has not been associated with transplantation previously. In conclusion, the majority of the differentially expressed genes in graft endothelial cells are affected by the transplantation procedure whereas relatively few are associated with allograft rejection. [source] Assessment of physiological conditions in E. coli fermentations by epifluorescent microscopy and image analysisBIOTECHNOLOGY PROGRESS, Issue 3 2009Sónia Carneiro Abstract The development of monitoring methods for assessing the physiological state of microorganisms during recombinant fermentation processes has been encouraged by the need to evaluate the influence of processing conditions in recombinant protein production. In this work, a technique based on microscopy and image analysis was developed that allows the simultaneous quantification of parameters associated with viability and fluorescent protein production in recombinant Escherichia coli fermentations. Images obtained from light microscopy with phase contrast are used to assess the total number of cells in a given sample and, from epifluorescence microscopy, both protein producing and injured cells are evaluated using two different fluorochromes: propidium iodide and enhanced yellow fluorescent protein. This technique revealed the existence of different cell populations in the recombinant E. coli fermentation broth that were evaluated along four batch fermentations, complementing information obtained with standard techniques to study the effects of the temperature and induction time in recombinant protein production processes. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] | |||||||||||||