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Kleinberger G.,Universiteitsplein 1 | Kleinberger G.,Bunge | Kleinberger G.,University of Antwerp | Wils H.,Universiteitsplein 1 | And 15 more authors.
Journal of Neurochemistry

Null mutations in progranulin (GRN) are associated with frontotemporal lobar degeneration characterized by intraneuronal accumulation of TAR DNA-binding protein-43 (TDP- 43). However, the mechanism by which GRN deficiency leads to neurodegeneration remains largely unknown. In primary cortical neurons derived from Grn knockout (Grn -/-) mice, we found that Grn-deficiency causes significantly reduced neuronal survival and increased caspase-mediated apoptosis, which was not observed in primary mouse embryonic fibroblasts derived from (Grn -/-) mice. Also, neurons derived from (Grn -/-) mice showed an increased amount of pTDP-43 accumulations. Furthermore, proteasomal inhibition with MG132 caused increased caspase-mediated TDP-43 fragmentation and accumulation of detergent-insoluble 35- and 25-kDa C-terminal fragments in (Grn -/-) neurons and mouse embryonic fibroblasts. Interestingly, fulllength TDP-43 also accumulated in the detergent-insoluble fraction, and caspase-inhibition prevented MG132-induced generation of TDP-43 C-terminal fragments but did not block the pathological conversion of full-length TDP-43 from soluble to insoluble species. These data suggest that GRN functions as a survival factor for cortical neurons and GRN-deficiency causes increased susceptibility to cellular stress. This leads to increased aggregation and accumulation of full-length TDP-43 along with its C-terminal derivatives by both caspase-dependent and independent mechanisms. © 2010 The Authors. Source

Bols P.E.J.,Laboratory of Veterinary Physiology | Aerts J.M.J.,Laboratory of Cell Biology and Histology | Langbeen A.,Laboratory of Veterinary Physiology | Goovaerts I.G.F.,Laboratory of Veterinary Physiology | Leroy J.L.M.R.,Laboratory of Veterinary Physiology

Nowadays, in vitro study of follicular dynamics of primordial and primary follicular stages is limited because in vitro culture systems for these follicles are lacking, both in domestic animal species and in human. Therefore, additional insights might be generated by grafting ovarian tissue into immunodeficient mice to study activation and maturation of early follicular stages. A considerable amount of data has already been gathered in laboratory animals and through clinical application of human assisted reproduction technologies where live births were reported recently after the use of (cryopreserved) ovarian grafts. However, given that human preantral follicles are difficult to obtain and that there are many similarities between the bovine and human species with regard to ovarian physiology, the bovine model offers exciting additional prospects and is therefore discussed in more detail. This review will focus on recent developments related to preantral follicle and (repeated) ovarian tissue retrieval and xenotransplantation of (bovine) ovarian tissue strips to immunodeficient mice as a model to study preantral follicular dynamics. Different grafting strategies will be discussed as well as the consequences of this procedure on the viability and dynamic behavior of the grafted tissue and follicles. © 2010 Elsevier Inc. All rights reserved. Source

Everaert B.R.,University of Antwerp | Everaert B.R.,Laboratory of Cell Biology and Histology | Bergwerf I.,University of Antwerp | De Vocht N.,University of Antwerp | And 4 more authors.
BMC Biotechnology

Background: Despite positive reports on the efficacy of stem cell therapy for the treatment of cardiovascular disease, the nature of stem cell homing to ischemic tissues remains elusive.Results: We used a mouse model of peripheral tissue ischemia to study the survival and homing capacity of dual reporter gene (eGFP/Luciferase) expressing bone marrow-derived stromal cells (BMSC). Cell homing and survival were studied in the presence and absence of ciclosporin A (CsA) immunosuppression using bioluminescence imaging (BLI) together with confocal endomicroscopy. Different injection strategies were applied: central venous (CV), intra-arterial (IA) and intramuscular (IM). BLI and confocal endomicroscopy evidenced complete rejection of the IM injected allogeneic BMSC transplant within 5 to 10 days. Immunosuppression with CsA could only marginally prolong graft survival. IM injected BMSC did not migrate to the site of the arterial ligation. CV injection of BMSC resulted in massive pulmonary infarction, leading to respiratory failure and death. Intrapulmonary cell trapping was evidenced by confocal endomicroscopy, BLI and fluorescence microscopy. IA injection of BMSC proved to be a feasible and safe strategy to bypass the lung circulation. During the follow-up period, neither BLI nor confocal endomicroscopy revealed any convincing ischemia-directed homing of BMSC.Conclusions: BLI and confocal endomicroscopy are complementary imaging techniques for studying the in vivo biology of dual reporter gene-expressing BMSC. Allogeneic BMSC survival is limited in an immunocompetent host and cannot be preserved by CsA immunosuppression alone. We did not find substantial evidence for ischemia-directed BMSC homing and caution against CV injection of BMSC, which can lead to massive pulmonary infarction. © 2012 Everaert et al.; licensee BioMed Central Ltd. Source

Rychter J.W.,University Utrecht | Van Nassauw L.,Laboratory of Cell Biology and Histology | Van Nassauw L.,University of Antwerp | Timmermans J.-P.,Laboratory of Cell Biology and Histology | And 4 more authors.
Neurogastroenterology and Motility

Background: The parasitized or inflamed gastrointestinal mucosa shows an increase in the number of mucosal mast cells (MMC) and the density of extrinsic primary afferent nerve fibers containing the neuropeptide, calcitonin gene-related peptide (CGRP). Currently, the mode of action of CGRP on MMC is unknown. Methods: The effects of CGRP on mouse bone marrow-derived mucosal mast cells (BMMC) were investigated by measurements of intracellular Ca 2+ [Ca 2+] i and release of mMCP-1. Key Results: Bone marrow-derived mucosal mast cells responded to the application of CGRP with a single transient rise in [Ca 2+] i. The proportion of responding cells increased concentration-dependently to a maximum of 19 ± 4% at 10 -5 mol L -1 (mean ±SEM; C48/80 100%; EC 50 10 -8 mol L -1). Preincubation with the CGRP receptor antagonist BIBN4096BS (10 -5 mol L -1) completely inhibited BMMC activation by CGRP [range 10 -5 to 10 -11 mol L -1; analysis of variance (anova)P < 0.001], while preincubation with LaCl 3 to block Ca 2+ entry did not affect the response (P = 0.18). The presence of the CGRP1 receptor on BMMC was confirmed by simultaneous immunofluorescent detection of RAMP1 or CRLR, the two components of the CGRP1 receptor, and mMCP-1. Application of CGRP for 1 h evoked a concentration-dependent release of mMCP-1 (at EC 50 10% of content) but not of β-hexosaminidase and alterations in granular density indicative of piecemeal release.Conclusions & Inferences We demonstrate that BMMC express functional CGRP1 receptors and that their activation causes mobilization of Ca 2+ from intracellular stores and piecemeal release of mMCP-1. These findings support the hypothesis that the CGRP signaling from afferent nerves to MMC in the gastrointestinal wall is receptor-mediated. © 2010 Blackwell Publishing Ltd. Source

Bilbao E.,Laboratory of Cell Biology and Histology | Raingeard D.,Laboratory of Cell Biology and Histology | de Cerio O.D.,Laboratory of Cell Biology and Histology | Ortiz-Zarragoitia M.,Laboratory of Cell Biology and Histology | And 6 more authors.
Aquatic Toxicology

Thicklip grey mullets Chelon labrosus inhabit coastal and estuarine areas where they can be chronically exposed to commonly released pollutants such as polycyclic aromatic hydrocarbons (PAHs) and perfluorinated compounds. These pollutants can also originate from accidental spills, such as the Prestige oil spill in 2002, which resulted in the release of a heavy fuel oil that affected coastal ecosystems in the Bay of Biscay. Peroxisome proliferation (PP), induced biotransformation metabolism, immunosuppression and endocrine disruption are some of the possible biological effects caused by such chemicals. With the aim of studying the effects of organic toxic chemicals on such biological processes at the transcriptional and at the cell/tissue level, juvenile mullets were exposed to the typical mammalian peroxisome proliferator perfluorooctane sulfonate (PFOS), and to fresh (F) and weathered (WF) Prestige-like heavy fuel oil for 2 and 16 days. First, fragments of genes relevant to biotransformation, immune/inflammatory and endocrine disruption processes were cloned using degenerate primers. Fuel oil elicited a significant PP response as proved by the transcriptional upregulation of palmitoyl-CoA oxidase (aox1), peroxisome proliferator activated receptor α (pparα) and retinoic X receptor, by the AOX1 activity induction and by the increased peroxisomal volume density. PFOS only elicited a significant induction of AOX1 activity at day 2 and of PPARα mRNA expression at day 16. All treatments significantly increased catalase mRNA expression at day 16 in liver and at day 2 in gill. Cyp1a transcription (liver and gill) and EROD activity were induced in fuel oil treated organisms. In the case of phase II metabolism only hepatic glutathione S-transferase mRNA was overexpressed in mullets exposed to WF for 16 days. Functionally, this response was reflected in a significant accumulation of bile PAH metabolites. WF treated fish accumulated mainly high molecular weight metabolites while F exposure resulted in accumulation of mainly low molecular ones. Fuel oil significantly regulated immune response related complement component C3 and hepcidin transcription followed by a significant regulation of inflammatory response related apolipoprotein-A1 and fatty acid binding protein mRNAs at day 16. These responses were accompanied by a significant hepatic inflammatory response with lymphocyte accumulations (IRLA) and accumulation of melanomacrophage centers (MMC). PFOS did not elicit any transcriptional response in the studied biotransformation and immune related genes, although histologically significant effects were recorded in IRLA and MMC. A significant reduction of lysosomal membrane stability was observed in all exposed animals. No endocrine disruption effects were observed in liver while brain aromatase mRNA was overexpressed after all treatments at day 2 and estrogen receptor α was downregulated under WF exposure at day 16. These results show new molecular and cellular biomarkers of exposure to organic chemicals and demonstrate that in mullets PP could be regulated through molecular mechanisms similar to those in rodents, although the typical mammalian peroxisome proliferator PFOS and heavy fuel oil follow divergent mechanisms of action. © 2010 Elsevier B.V. Source

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