Yoo-Jin Shin

Catholic University of Korea, Sŏul, Seoul, South Korea

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Publications (28)77.85 Total impact

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    ABSTRACT: Slit2 is a secreted glycoprotein that was originally identified as a chemorepulsive factor in the developing brain; however, it was recently reported that Slit2 is associated with adult neuronal function including a variety of pathophysiological processes. To elucidate whether Slit2 is implicated in the pathophysiology of ischemic injury, we investigated the temporal changes and cellular localization of Slit2 and its predominant receptors, Robo1 and Robo4, for 28 days after transient forebrain ischemia. Slit2 and its receptors had similar overall expression patterns in the control and ischemic hippocampi. The ligand and receptors were constitutively expressed in hippocampal neurons in control animals; however, in animals with ischemic injury, their upregulation was detected in reactive astrocytes, but not in neurons or activated microglia, in the CA1 region. Astroglial induction of Slit2 and its receptors occurred by day 3 after reperfusion, and appeared to increase progressively until the final time point on day 28. Their temporal expression patterns overlapped with the time period in which reactive astrocytes undergo dynamic structural changes and appear hypertrophic in the ischemic hippocampus. The immunohistochemical data were consistent with the results of the immunoblot analyses, indicating that the expression of Slit2 and Robo increased progressively over the relatively long period of 28 days examined here. Collectively, these results suggest that Slit2/Robo signaling may be involved in regulating the astroglial reaction via autocrine or paracrine mechanisms in post-ischemic processes. Moreover, this may contribute to the dynamic morphological changes that occur in astrocytes in response to ischemic injury.
    No preview · Article · Jan 2016 · Brain research
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    ABSTRACT: The suppressor of cytokine signaling 2 (SOCS2) has been reported to be involved in astroglial reactions and adult neurogenesis in the ischemic hippocampus. To elucidate whether SOCS2 is implicated in the pathophysiology of stroke, we investigate spatiotemporal regulation and identification of cell phenotypes expressing SOCS2 after transient focal cerebral ischemia. Weak hybridization signals for SOCS2 mRNA were constitutively observed in striatal neurons and upregulation of SOCS2 mRNA was induced in association with nestin-positive cells in stroke-lesioned rats. Analysis of the characteristics and phenotypes of SOCS2/nestin double-labeled cells revealed spatial differences between infarct and peri-infarct areas. SOCS2/nestin double-labeled cells in the infarct area were associated with the vasculature and were highly proliferative. In contrast, the double-labeled cells in the peri-infarct area were indeed glial fibrillary acidic protein (GFAP)-positive reactive astrocytes forming the glial scar, although nestin-negative reactive astrocytes also exhibited weak SOCS2 expression. In addition, induction of SOCS2 expression was observed in Iba1-positive cells showing a macrophage-like phenotype with amoeboid morphology; these cells were predominantly localized in the infarct area. In the peri-infarct area, only a small proportion of Iba1-positive cells with the morphology of brain macrophages expressed SOCS2 and most activated stellate microglial cells with thick and short processes exhibited weak or negligible SOCS2 expression. Thus, our results revealed the phenotypic and functional heterogeneity of SOCS2-expressing cells within infarct and peri-infarct areas, suggesting the involvement of SOCS2 in astroglial reactions and activation/recruitment of brain macrophages and its potential role in perivascular progenitors/stem cells after ischemic stroke.
    No preview · Article · Nov 2015 · Cell and Tissue Research
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    ABSTRACT: The mycotoxin 3-nitropropionic acid (3NP) is an irreversible inhibitor that induces neuronal damage by inhibiting mitochondrial complex II. Neurodegeneration induced by 3NP, which is preferentially induced in the striatum, is caused by an excess influx and accumulation of calcium in mitochondria. Osteopontin (OPN) is a glycosylated phosphoprotein and plays a role in the regulation of calcium precipitation in the injured brain. The present study was designed to examine whether induction of OPN protein is implicated in the pathogenesis of 3NP-induced striatal neurodegeneration. We observed overlapping regional expression of OPN, the neurodegeneration marker Fluoro-Jade B, and the microglial marker ionized calcium-binding adaptor molecule 1 (Iba1) in the 3NP-lesioned striatum. OPN expression was closely associated with the mitochondrial marker NADH dehydrogenase (ubiquinone) flavoprotein 2 in the damaged striatum. In addition, immunoelectron microscopy demonstrated that OPN protein was specifically localized to the inner membrane and matrix of the mitochondria in degenerating striatal neurons, and cell fragments containing OPNlabeled mitochondria were also present within activated brain macrophages. Thus, our study revealed that OPN expression is associated with mitochondrial dysfunction produced by 3NP-induced alteration of mitochondrial calcium homeostasis, suggesting that OPN is involved in the pathogenesis of striatal degeneration by 3NP administration.
    Full-text · Article · Oct 2015 · Acta histochemica et cytochemica official journal of the Japan Society of Histochemistry and Cytochemistry
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    ABSTRACT: Intracellular calcium accumulation is associated with cell death in several neuropathological disorders including brain ischemia, but the exact mechanisms of calcification need to be clarified. We used organotypic hippocampal slice culture cultures subjected to oxygen-glucose deprivation (OGD) mimicking the in vivo situation to investigate the events underlying ectopic calcification. Alizarin red staining indicating calcium deposition was observed in the cornu ammonis (CA)1 and dentate gyrus regions in control hippocampal slices despite no specific labeling for cell death markers. Electron microscopy using the osmium/potassium dichromate method revealed scattered degenerated cells throughout the normally appearing CA1 region. They contained electron-dense precipitates within mitochondria, and electron probe microanalysis confirmed that they were calcifying mitochondria. Selective calcium deposition was noted within, but not beyond, mitochondria in these mineralized cells. They showed ultrastructural features of non-necrotic, non-apoptotic cell death and retained their compact ultrastructure, even after the majority of mitochondria were calcified. Unexpectedly, no intracellular calcification was noted in necrotic CA1 pyramidal cells after OGD, and there was no progression of calcification in OGD-lesioned slices. In addition, mineralized cells in both control and OGD-lesioned slices were closely associated with or completely engulfed by astrocytes but not microglia. These astrocytes were laden with heterogeneous cytoplasmic inclusions that appeared to be related with their phagocytic activity. These data demonstrate that microcalcification specifically associated with mitochondria might lead to a novel type of cell death and suggest that astrocytes may be involved in the phagocytosis of these mineralized cells and possibly in the regulation of ectopic calcification. Copyright © 2015 Elsevier B.V. All rights reserved.
    No preview · Article · Jul 2015 · Brain research
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    ABSTRACT: G-protein-coupled calcium-sensing receptor (CaSR) has been recently recognized as an important modulator of diverse cellular functions, beyond the regulation of systemic calcium homeostasis. To identify whether CaSR is involved in the pathophysiology of stroke, we studied the spatiotemporal regulation of CaSR protein expression in rats undergoing transient focal cerebral ischemia, which was induced by middle cerebral artery occlusion. We observed very weak or negligible immunoreactivity for CaSR in the striatum of sham-operated rats, as well as in the contralateral striatum of ischemic rats after reperfusion. However, CaSR expression was induced in the ischemic and border zones of the lesion in ischemic rats. Six hours post-reperfusion there was an upregulation of CaSR in the ischemic zone, which seemed to decrease after seven days. This upregulation preferentially affected some neurons and cells associated with blood vessels, particularly endothelial cells and pericytes. In contrast, CaSR expression in the peri-infarct region was prominent three days after reperfusion, and with the exception of some neurons, it was mostly located in reactive astrocytes, up to day 14 after ischemia. On the other hand, activated microglia/macrophages in both the ischemic and border zones were devoid of specific labeling for CaSR at any time point after reperfusion, despite their massive infiltration in both regions. Our results show heterogeneity in CaSR-positive cells within the ischemic and border zones, suggesting that CaSR expression is regulated in response to the altered extracellular ionic environment caused by ischemic injury. Thus, CaSR may have a multifunctional role in the pathophysiology of ischemic stroke, possibly in vascular remodeling and astrogliosis. Copyright © 2015. Published by Elsevier B.V.
    No preview · Article · May 2015 · Journal of chemical neuroanatomy
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    ABSTRACT: To determine whether vascular endothelial growth factor-C (VEGF-C) and its receptor (VEGFR-3) are involved in the glial reaction elicited by transplanted mesenchymal stem cells (MSCs), we examined the cellular localization of VEGF-C and VEGFR-3 proteins in the striatum of adult normal rats that received bone marrow-derived human MSCs. The MSC grafts were infiltrated with activated microglia/macrophages and astrocytes over a 2-week period post-transplantation, which appeared to parallel the loss of transplanted MSCs. VEGF-C/VEGFR-3 was expressed in activated microglia/macrophages recruited to the graft site, where the induction of VEGF-C protein was rather late compared with that of its receptor. VEGF-C protein was absent or very weak on day 3, whereas VEGFR-3 immunoreactivity was evident within the first three days. Furthermore, within three days, VEGF-C could be detected in the brain macrophages localized immediately adjacent to the needle track. At the same time, almost all the brain macrophages in both regions expressed VEGFR-3. Reactive astrocytes at the graft site expressed VEGFR-3, but not VEGF-C. These data demonstrated the characteristic time- and cell-dependent expression patterns for VEGF-C and VEGFR-3 within the engrafted brain tissue, suggesting that they may contribute to neuroinflammation in MSC transplantation, possibly through the recruitment and/or activation of microglia/macrophages and astrogliosis. © The Author(s) 2014.
    No preview · Article · Dec 2014 · Journal of Histochemistry and Cytochemistry
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    Joo-Hee Park · Yoo-Jin Shin · Tae-Ryong Riew · Mun-Yong Lee
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    ABSTRACT: MAZ51 is an indolinone-based molecule originally synthesized as a selective inhibitor of vascular endothelial growth factor receptor (VEGFR)-3 tyrosine kinase. This study shows that exposure of two glioma cell lines, rat C6 and human U251MG, to MAZ51 caused dramatic shape changes, including the retraction of cellular protrusions and cell rounding. These changes were caused by the clustering and aggregation of actin filaments and microtubules. MAZ51 also induced G2/M phase cell cycle arrest. This led to an inhibition of cellular proliferation, without triggering significant cell death. These alterations induced by MAZ51 occurred with similar dose- and time-dependent patterns. Treatment of glioma cells with MAZ51 resulted in increased levels of phosphorylated GSK3β through the activation of Akt, as well as increased levels of active RhoA. Interestingly, MAZ51 did not affect the morphology and cell cycle patterns of rat primary cortical astrocytes, suggesting it selectively targeted transformed cells. Immunoprecipitation-western blot analyses indicated that MAZ51 did not decrease, but rather increased, tyrosine phosphorylation of VEGFR-3. To confirm this unanticipated result, several additional experiments were conducted. Enhancing VEGFR-3 phosphorylation by treatment of glioma cells with VEGF-C affected neither cytoskeleton arrangements nor cell cycle patterns. In addition, the knockdown of VEGFR-3 in glioma cells did not cause morphological or cytoskeletal alterations. Furthermore, treatment of VEGFR-3-silenced cells with MAZ51 caused the same alterations of cell shape and cytoskeletal arrangements as that observed in control cells. These data indicate that MAZ51 causes cytoskeletal alterations and G2/M cell cycle arrest in glioma cells. These effects are mediated through phosphorylation of Akt/GSK3β and activation of RhoA. The anti-proliferative activity of MAZ51 does not require the inhibition of VEGFR-3 phosphorylation, suggesting that it is a potential candidate for further clinical investigation for treatment of gliomas, although the precise mechanism(s) underlying its effects remain to be determined.
    Full-text · Article · Sep 2014 · PLoS ONE
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    ABSTRACT: Krüppel-like factor 4 (KLF4) is a transcription factor with diverse and cell type-specific functions and is associated with a variety of pathophysiological processes. Recently, it has been proposed that the regulation of KLF4 is critical to neuronal differentiation and that neural progenitors overexpressing KLF4 take on a glial identity. The present study aimed to determine whether KLF4 is involved in the astroglial reaction induced by ischemia-reperfusion injury in the brain. No specific KLF4 immunoreactivity was observed in resting astrocytes of the control hippocampus, but significant induction was detected in reactive astrocytes preferentially located in the CA1 and dentate hilar regions of the hippocampus following transient forebrain ischemia. Astroglial KLF4 expression was induced in the nuclei and cytoplasm within 3 days of ischemia and persisted for at least 4 weeks. This pattern was reproduced in an in vitro astrogliosis model of rat primary cortical astrocytes exposed to oxygen-glucose deprivation (OGD). Furthermore, immunoblot assay showed that nuclear and cytosolic extracts from cortical astrocytes subjected to OGD had significantly higher levels of KLF4 protein compared to normoxic extracts. Thus, our data demonstrate that KLF4 expression was induced in astroglia by ischemic injury both in vivo and in vitro, suggesting that KLF4 may act as a transcription factor linked to the regulation of the astroglial reaction following ischemic injury.
    No preview · Article · Aug 2013 · Histochemie
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    Jeong Min Cho · Yoo-Jin Shin · Jang-Mi Park · Jin Kim · Mun-Yong Lee
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    ABSTRACT: Recent studies have suggested that nestin facilitates cellular structural remodeling in vasculature-associated cells in response to ischemic injury. The current study was designed to investigate the potential role of post-ischemic nestin expression in parenchymal astrocytes. With this aim, we characterized ischemia-induced nestin expression in the CA1 hippocampal region, an area that undergoes a delayed neuronal death, followed by a lack of neuronal generation after transient forebrain ischemia. Virtually all of the nestin-positive cells in the ischemic CA1 hippocampus were reactive astrocytes. However, induction of nestin expression did not correlate simply with astrogliosis, but rather showed characteristic time- and strata-dependent expression patterns. Nestin induction in astrocytes of the pyramidal cell layer was rapid and transient, while a long-lasting induction of nestin was observed in astrocytes located in the CA1 dendritic subfields, such as the stratum oriens and radiatum, until at least day 28 after ischemia. There was no detectable expression in the stratum lacunosum moleculare despite the evident astroglial reaction. Almost all of the nestin-positive cells also expressed a transcription factor for neural/glial progenitors, i.e., Sox-2 or Sox-9, and some cells were also positive for Ki-67. However, all of the nestin-positive astrocytes expressed the calcium-binding protein S100β, which is known to be expressed in a distinct, post-mitotic astrocyte population. Thus, our data indicate that in the ischemic CA1 hippocampus, nestin expression was induced in astroglia that were becoming reactive, but not in a progenitor/stem cell population, suggesting that nestin may allow for the structural remodeling of these cells in response to ischemic injury.
    Preview · Article · Jun 2013 · Anatomy & cell biology
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    ABSTRACT: The present study aimed to provide a detailed characterization of the cellular phenotypes of nestin-positive cells in a rat model of ischemic stroke. Nestin-positive cells included reactive astrocytes in the peri-infarct region. In the ischemic core, in which astrocytes had virtually disappeared, nestin expression was exclusively associated with the vasculature, including the microvasculature and larger caliber vessels. Induction of nestin expression in the ischemic core occurred by 3 days post-ischemia. Nestin expression continued through at least 28 days post-ischemia but the cellular profiles of nestin-positive cells changed over this period. In the ischemic core at day 3, nestin-positive cells frequently had long processes that ran parallel along the longitudinal axis of the vasculature. These cells were highly proliferative and expressed the transcription factor for neural/glial progenitors, Sox9. Based on their morphological characteristics and on a double-labeling study, most nestin-positive cells were clearly distinguishable from vasculature-associated cells including endothelial cells, smooth muscle cells and microglia/macrophages. Immunoelectron microscopic findings demonstrated that most nestin-positive cells lay in the perivascular space and had macrophage-like features, indicating morphological similarity to perivascular macrophages. Nestin expression was still associated with the vasculature 14 days after ischemia but appeared in fibroblast-like cells. Thus, our data indicated that, in the ischemic core, nestin expression was not limited to a progenitor/stem cell population but was induced in the vasculature-associated cells. These cell types included perivascular macrophages and fibroblast-like cells that appeared to undergo dynamic structural changes. These results suggest that nestin facilitates cellular structural remodeling in response to ischemic injury.
    No preview · Article · Dec 2012 · Cell and Tissue Research
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    ABSTRACT: We investigated the spatiotemporal expression of vascular endothelial growth factor receptor-3 (VEGFR-3) in the spinal cord of Lewis rats with experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis. VEGFR-3 mRNA and protein were constitutively expressed in gray matter neurons and in a few white matter astrocytes. Induction of VEGFR-3 occurred predominantly in perivascular infiltrated macrophages in the spinal cord white matter during the inductive phase of EAE. VEGFR-3 expression was also induced in activated microglial cells in the gray and white matter, mainly in the peak phase. In addition, reactive astrocytes in the white matter, but not in the gray matter, expressed VEGFR-3 as disease severity increased. These data suggest that VEGFR-3 is involved in the recruitment of monocytic macrophages and in glial reactions during EAE.
    Preview · Article · Sep 2012 · Journal of Histochemistry and Cytochemistry
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    ABSTRACT: Vascular endothelial growth factor receptor (VEGFR)-3, a receptor for VEGF-C and VEGF-D, has recently been reported to be induced within vessel-like structures in the ischemic brain. The purpose of the present study was to characterize and define further the cellular phenotypes of vascular-associated cells that manifest induced VEGFR-3 expression in a rat model of ischemic stroke. Vessel-associated cells expressing VEGFR-3 were found to be perivascular astrocytes in the peri-infarct region, whereas in the ischemic core, where astrocytes had virtually disappeared, induction of VEGFR-3 mRNA and protein was still prominent in vascular structures 3-7 days after reperfusion. VEGFR-3 and nestin expression were colocated in almost all cells associated with the vasculature in the ischemic core, and most (∼82%) of the VEGFR-3/nestin double-labeled cells were proliferative. A subpopulation of these VEGFR-3-expressing cells appeared to be included in two immunophenotypically distinct perivascular cells: NG2-positive pericytes and ED2- or OX6-perivascular macrophages. However, most of these cells did not show markers for vasculature-associated cell types such as endothelial cells, microglia/macrophages, and smooth muscle cells. Thus, our data indicated that vasculature-associated VEGFR-3-expressing cells in the ischemic core may represent a heterogeneous population of cells with functional diversity, rather than a uniform cell type.
    No preview · Article · Jul 2012 · Acta histochemica
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    ABSTRACT: The present study was designed to evaluate the extent and topography of osteopontin (OPN) protein expression in the rat hippocampus 4 to 12 weeks following transient forebrain ischemia, and to compare OPN expression patterns with those of calcium deposits and astroglial and microglial reactions. Two patterns of OPN staining were recognized by light microscopy: 1) a diffuse pattern of tiny granular deposits throughout the CA1 region at 4 weeks after ischemia and 2) non-diffuse ovoid to round deposits, which formed conglomerates in the CA1 pyramidal cell layer over the chronic interval of 8 to 12 weeks. Immunogold-silver electron microscopy and electron probe microanalysis demonstrated that OPN deposits were indeed diverse types of calcium deposits, which were clearly delineated by profuse silver grains indicative of OPN expression. Intracellular OPN deposits were frequently observed within reactive astrocytes and neurons 4 weeks after ischemia but rarely at later times. By contrast, extracellular OPN deposits progressively increased in size and appeared to be gradually phagocytized by microglia or brain macrophages and some astrocytes over 8 to 12 weeks. These data indicate an interaction between OPN and calcium in the hippocampus in the chronic period after ischemia, suggesting that OPN binding to calcium deposits may be involved in scavenging mechanisms.
    Preview · Article · Apr 2012 · Journal of Histochemistry and Cytochemistry
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    ABSTRACT: Osteopontin (OPN), an adhesive glycoprotein, has recently been proposed to act as an opsonin that facilitates phagocytosis of neuronal debris by macrophages in the ischemic brain. The present study was designed to elucidate the process whereby OPN binds to neuronal cell debris in a rat model of ischemic stroke. Significant co-localization of the OPN protein and calcium deposits in the ischemic core were observed by combining alizarin red staining and OPN immunohistochemistry. In addition, electron microscopy (EM) using the osmium/potassium dichromate method revealed that electron-dense precipitates, typical of calcium deposits, were localized mainly along the periphery of putative degenerating neurites. This topical pattern of calcium precipitates resembled the distribution of OPN as detected by immunogold-silver EM. Combining immunogold-silver EM and electron probe microanalysis further demonstrated that the OPN protein was localized at the periphery of cell debris or degenerating neurites, corresponding with locally higher concentrations of calcium and phosphorus, and that the relative magnitude of OPN accumulation was comparable to that of calcium and phosphorus. These data suggest that calcium precipitation provides a matrix for the binding of the OPN protein within the debris or degenerating neurites induced by ischemic injury. Therefore, OPN binding to calcium deposits may be involved in phagocytosis of such debris, and may participate in the regulation of ectopic calcification in the ischemic brain.
    No preview · Article · Nov 2011 · Journal of neurotrauma
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    ABSTRACT: Vascular endothelial growth factor receptor (VEGFR)-3/Flt4 binds VEGF-C and VEGF-D with high affinity. It has been suggested to be involved in neurogenesis and adult neuronal function. However, little is known about the localization of VEGFR-3 in the adult central nervous system (CNS). The present study presents, to our knowledge, the first detailed mapping of VEGFR-3 mRNA expression in adult rat brain and spinal cord by using in situ hybridization and reverse transcription-polymerase chain reaction analysis (RT-PCR). Varying VEGFR-3 expression intensity was detected in functionally diverse nuclei, with the highest levels in the mitral cells of the olfactory bulb, piriform cortex, anterodorsal thalamic nucleus, several nuclei of the hypothalamus, and the brainstem cranial nerve nuclei. VEGFR-3 mRNA was abundantly expressed in the ventral motor neurons of the spinal cord and in some circumventricular organs such as the median eminence and the area postrema. Moreover, the locus coeruleus and some of the nuclei of the reticular formation showed moderate-to-high hybridization signals. VEGFR-3 expression appeared to be localized mostly within neurons, but weak labeling was also found in some astrocytes. In particular, VEGFR-3 was highly expressed in ependymal cells of the ventral third ventricle and the median eminence, which were co-labeled with vimentin but not with glial fibrillary acidic protein, suggesting that these cells are tanycytes. RT-PCR analysis revealed similar levels of VEGFR-3 expression in all regions of the adult rat CNS. The specific but widespread distribution of VEGFR-3 mRNA in the adult rat CNS suggests that VEGFR-3 functions more broadly than expected, regulating adult neuronal function playing important roles in tanycyte function.
    No preview · Article · Jun 2011 · Journal of chemical neuroanatomy
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    ABSTRACT: Osteopontin (OPN) is an adhesive glycoprotein linked to a variety of pathophysiological processes. We investigated whether OPN might act as an opsonin in the diseased brain by studying the postischemic expression and localization of OPN mRNA and protein in a rat model of ischemic stroke. In addition, we characterized the subcellular localization of OPN protein in the ischemic brain core. Induction of OPN mRNA occurred in activated microglia/macrophages in the ischemic core on days 3-7 after reperfusion and this was sustained up to day 28, at least. OPN protein was synthesized and secreted by brain macrophages, which first surrounded damaged striatal white matter tracts and then infiltrated into them. Punctate OPN-immunoreactive profiles were scattered throughout the infarction core except in white matter bundles. Electron microscopy showed the localization of OPN protein along the membranes lining what appeared to be the debris of dead neurons. These were located in the extracellular space and within the cytoplasm of brain macrophages, indicating that the OPN protein accumulated selectively on the surface of dead cells, most of which were phagocytosed subsequently by brain macrophages. However, no significant induction of OPN occurred in degenerating striatal white matter tracts or in brain macrophage-engulfed axonic or myelin debris. These data suggest that OPN secreted by brain macrophages in this rat model of stroke might be involved in the phagocytosis of fragmented cell debris and possibly not in the phagocytosis of axonic or myelin debris.
    No preview · Article · Mar 2011 · Glia
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    ABSTRACT: The reaction of neuroactive substances to ischemic conditions in the rat retina evoked by different methods was immunochemically evaluated in adult Sprague-Dawley rats. Ocular ischemic conditions were unilaterally produced by elevating intraocular pressure (EIOP) or by middle cerebral artery occlusion (MCAO). Two EF-hand calcium binding proteins, calbindin D28K (CB) and calretinin (CR), in the normal retina showed similar immunolocalization, such as the amacrine and displaced amacrine cells, the ganglion cells, and their processes, particularly CB in horizontal cells. CB immunoreactive neurons in the ganglion cell layer in both types of ischemic retinas were more reduced in number than CR neurons compared to those in a normal retina. The CB protein level in both ischemic retinas was reduced to 60-80% of normal. The CR protein level in MCAO retinas was reduced to about 80% of normal but increased gradually to the normal value, whereas that in the EIOP showed a gradual reduction and a slight recovery. SMI32 immunoreactivity, which detects a dephosphorylated epitope of neurofilaments-M and -H, appeared in the axon bundles of ganglion cells in the innermost nerve fiber layer of normal retinas. The reactivity in the nerve fiber bundles appeared to only increase slightly in EIOP retinas, whereas a moderate increase occurred in MCAO retinas. The SMI32 protein level in MCAO retinas showed a gradual increasing tendency, whereas that in the EIOP showed a slight fluctuation. Interestingly, the MCAO retinas showed additional SMI32 immunoreactivity in the cell soma of presumed ganglion cells, whereas that of EIOP appeared in the Müller proximal radial fibers. Glial fibrillary acidic protein (GFAP) immunoreactivity appeared in the astrocytes located in the nerve fiber layer of normal retinas. Additional GFAP immunoreactivity appeared in the Müller glial fibers deep in EIOP retinas and at the proximal end in MCAO retinas. These findings suggest that the neurons in the ganglion cell layer undergo degenerative changes in response to ischemia, although EIOP retinas represented a remarkable Müller glial reaction, whereas MCAO retinas had only a small-scaled axonal transport disturbance.
    Preview · Article · Mar 2011 · Anatomy & cell biology
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    ABSTRACT: To identify whether vascular endothelial growth factor receptor (VEGFR)-3, a receptor for VEGF-C and VEGF-D, is involved in pathophysiology of stroke, we investigated the spatiotemporal regulation of VEGFR-3 mRNA after transient focal cerebral ischemia. Most of the increase in VEGFR-3 expression in the ischemic core could be attributed to brain macrophages, whereas VEGFR-3 in the peri-infarct penumbra region was predominantly expressed in reactive astrocytes. A subpopulation of VEGFR-3-expressing brain macrophages was positive for NG2 proteoglycan and showed proliferative activity. In addition, in vitro model of stroke revealed no significant induction of VEGFR-3 in activated microglial cells, indicating that infiltrating exogenous macrophages expressed VEGFR-3 after focal ischemia. These data suggest that VEGFR-3 may be involved in the glial reaction and possibly in the recruitment of monocytic macrophages during ischemic insults.
    No preview · Article · Dec 2010 · Journal of neuroimmunology
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    ABSTRACT: Vascular endothelial growth factor receptor (VEGFR)-3, a receptor for VEGF-C and VEGF-D, has recently been suggested to play an important role during neuronal development. To characterize its potential role in CNS ontogenesis, we investigated the spatiotemporal and cellular expression of VEGFR-3 in developing and mature rat cerebellum using in situ hybridization. VEGFR-3 expression appeared as early as E15, and was restricted to the ventricular zone of the cerebellar primordium, the germinative neuroepithelium, but was absent by E20. Instead, the expression area of VEGFR-3 in the cerebellum grew in parallel with cerebellar development. From E20 on, two populations of VEGFR-3-expressing cells can be clearly distinguished in the developing cerebellum: a population of differentiating and postmitotic neurons and the Bergmann glia. VEGFR-3 expression in neurons occurred during the period of neuronal differentiation, and increased with maturation. In particular, the expression of VEGFR-3 mRNA revealed different temporal patterns in different neuronal populations. Neurons generated early, Purkinje cells, and deep nuclear neurons expressed VEGFR-3 mRNA during late embryonic stages, whereas VEGFR-3 transcription in local interneurons appeared by P14 with weaker expression. In addition, Bergmann glia expressed VEGFR-3 throughout cerebellar maturation into adulthood. However, receptor expression was absent in the progenitors in the external granular layer and during further migration. The results of this study suggest that VEGFR-3 has even broader functions than previously thought, regulating both developmental processes and adult neuronal function in the cerebellum.
    No preview · Article · Nov 2010 · Cellular and Molecular Neurobiology
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    ABSTRACT: The heterodimeric sweet taste receptors, T1R2 and T1R3, have recently been proposed to be associated with the brain glucose sensor. To identify whether sweet taste signaling is regulated in response to an ischemic injury inducing acute impairment of glucose metabolism, we investigated the spatiotemporal expression of the sweet taste receptors and their associated taste-specific G-protein α-gustducin in the rat hippocampus after ischemia. The expression profiles of both receptor subunits and α-gustducin shared overlapping expression patterns in sham-operated and ischemic hippocampi. Constitutive expression of both receptors and α-gustducin was localized in neurons of the pyramidal cell and granule cell layers, but their upregulation was detected in reactive astrocytes in ischemic hippocampi. Immunoblot analysis confirmed the immmunohistochemically determined temporal patterns of sweet-taste signaling proteins. These results suggest that the expression of sweet taste signaling proteins in astrocytes might be regulated in response to altered extracellular levels of glucose following an ischemic insult.
    No preview · Article · Oct 2010 · Neurochemical Research