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Regulation of hyaluronan binding by F-actin and colocalization of CD44 and phosphorylated ezrin/radixin/moesin (ERM) proteins in myeloid cells.

Proinflammatory cytokines such as TNF-alpha up-regulate the expression of the cell adhesion molecule, CD44, and induce hyaluronan (HA) binding in peripheral blood monocytes (PBM). Here we show that in PBM, TNF-alpha induced cytoskeletal rearrangement, increased threonine phosphorylation of ERM proteins, and induced the redistribution and colocalization of phospho-ERM proteins (P-ERM) with CD44. In the myeloid progenitor cell line, KG1a, hyaluronan binding occurred in the pseudopod where CD44, P-ERM, and F-actin were highly localized. Hyaluronan binding correlated with high expression of both CD44 and P-ERM clustered in a single pseudopod. Disruption of polymerized actin reduced hyaluronan binding in both PBM and KG1a cells and abolished CD44 clustering and the pseudopod in KG1a cells. The pseudopod was not required for the clustering of CD44, the colocalization with P-ERM, or hyaluronan binding. However, treatment with a kinase inhibitor abolished ERM phosphorylation and reduced hyaluronan binding. Furthermore, expression of CD44 lacking the putative ERM binding site resulted in reduced hyaluronan binding. Taken together, these data suggest that CD44-mediated hyaluronan binding in human myeloid cells is regulated by P-ERM and the actin cytoskeleton.

Actins↗

Somatostatin-like immunoreactivity in the brain of the urodele amphibian Pleurodeles waltl. Colocalization with catecholamines and nitric oxide.

The neuronal structures with somatostatin-like immunoreactivity have been studied in the brain of the urodele amphibian Pleurodeles waltl. Intense immunoreactivity was observed in neurons and fibers distributed throughout the brain. Within the telencephalon, the subpallial regions were densely labeled containing both cells and fibers, primarily in the striatum and amygdala. The majority of the somatostatin immunoreactive neurons were located in the preoptic area and hypothalamus, although less numerous cells were also found in the thalamus. A conspicuous innervation of the median eminence was revealed, which arises from the hypothalamic cell populations. In the brainstem, intense fiber labeling was present in the tectum and tegmentum, whereas cell bodies were located only in the tegmentum of the mesencephalon and in the interpeduncular, raphe and reticular nuclei of the rhombencephalon. Longitudinal fiber tracts throughout the brainstem were observed and they continued into the spinal cord in the laterodorsal funiculus. The localization of somatostatin in catecholaminergic and nitrergic neurons was studied by double labeling techniques with antisera against tyrosine hydroxylase and nitric oxide synthase. Catecholamines and somatostatin only colocalized in a cell population in the ventral preoptic area. In turn, the striatum and amygdala contained neurons with somatostatin and nitric oxide synthase. Our results demonstrated that the somatostatin neuronal system in the brain of Pleurodeles waltl is consistent with that observed in anuran amphibians and shares many characteristics with those of amniotes. Colocalization of somatostatin with catecholamines and nitric oxide is very restricted in the urodele brain, but in places that can be easily compared to those reported for mammals, suggesting that interactions between these neurotransmitter systems are a primitive feature shared by tetrapod vertebrates.

Animals↗

Calretinin mRNA and immunoreactivity in the medullary reticular formation of the rat: colocalization with glutamate receptors.

Calretinin-positive cells were identified in the medullary reticular formation of the rat by both immunohistochemistry and in situ hybridization histochemistry. In addition, double immunocytochemical labeling was used to examine the degree of colocalization of calretinin with GluR2/R3, GluR4 and GluR5-7 glutamate receptor subtypes. Results indicated regional variation in calretinin expression across reticular formation regions with the exception of the largest cells which were mostly calretinin-positive. Calretinin mRNA was particularly abundant in the parvocellular reticular nucleus. Most calretinin-immunoreactive cells also expressed at least one of the glutamate receptor subtypes examined with the exception of the smallest calretinin-positive cells of the parvocellular reticular formation which were generally not immunoreactive for any of the glutamate receptors examined. Calretinin immunoreactivity was colocalized with immunoreactivity for all three glutamate receptor subtypes examined in most of the large cells of the reticular formation. Immunoreactivity for the GluR4 antibody was least abundant in the reticular formation and GluR4 immunoreactive cells were least likely to co-express calretinin. These results suggest that calretinin and glutamate receptor antibodies may be used to identify specific subsets of reticular formation neurons.

Animals↗

Regional distribution of neural cell adhesion molecule immunoreactivity in the adult rat telencephalon and diencephalon. Partial colocalization with heparan sulfate proteoglycan immunoreactivity.

In the present paper immunocytochemical analysis at the fluorescence microscopical level has been performed of neural cell adhesion. molecule (NCAM) immunoreactivity in the adult rat tel- and diencephalon in order to further substantiate the highly selective neuronal localization of NCAM immunoreactivity, using an affinity purified rabbit antiserum recognizing homologous NCAM proteins from rat brain. Also, double immunolabelling experiments were performed with monoclonal antibodies specific for heparan sulfate related epitopes or gamma-aminobutyric acid (GABA) to establish in which cell populations a colocalization existed with immunoreactive heparan sulfate proteoglycans of GABA. Within the neocortex NCAM immunoreactivity was exclusively localized to the area of the cell membrane of soma and proximal dendrites of subsets of large pyramidal nerve cells of the layer 5 of the frontoparietal cortex. Within the dorsal hippocampus, the NCAM immunoreactivity was exclusively located to the cell surface area of the pyramidal cell bodies of area CA2. Two colour immunofluorescence procedures demonstrated a colocalization of NCAM and 3G10 but not 10E4 immunoreactivities in the cell surface area of many of the NCAM-positive nerve cell bodies of these two regions. Within the thalamus, strong NCAM immunoreactivity was exclusively demonstrated at all rostrocaudal levels of the reticular thalamic nucleus. The horizontal band of NCAM immunoreactivity was not continuous, but split up into patches of NCAM immunoreactivity within groups of nerve cell bodies. When analysing the number of cells per unitary square in the rostrocaudal direction, a significant increase of positive cells was found in the rostral and middle thirds versus the caudal third of the reticular thalamic nucleus. Many of the cell bodies with NCAM immunoreactivity in their cell surface are showed cytoplasmic GABA immunoreactivity. In the three regions shown to contain NCAM immunoreactivity, proteins of the NCAM type may play a special role for the maintenance of the synaptic structure. The findings also suggest that the sulfated proteoglycans and NCAM can interact in the regulation of cell-cell interaction via adhesion. In the reticular thalamic nucleus NCAM molecules may be part of a set of cell-adhesion molecules involved in a structural organization of the nucleus, which allows it to play a key role in relating cortical maps to thalamic maps.

Animals↗

Expression of NADPH-diaphorase and colocalization with Fos in the brain neurons of the rat following visceral noxious stimulation.

We used double staining immunocytochemical techniques to determine whether nitric oxide (NO) and Fos immunoreactivity induced by noxious visceral stimulation were colocalized in the neurons of the supraspinal areas. We observed a considerable increase in Fos-positive neurons in many brain areas after noxious stimulation but only 15% of the Fos-positive neurons colocalized Nicotinamide Adenine Dinucleotide Phosphate Diaphorase (NADPH-d). The NADPH-d positive cells showed perikarya and cytoplasmic processes laying next to or more frequently apposed to Fos-positive neurons. This anatomical finding supported the hypothesis that also at supraspinal level NO is released near the neurons specifically activated and diffuses through the source cells to act on adjacent neurons playing a role in the central processing of pain transmission and modulation.

Animals↗

Colocalization of arginine-vasotocin and chicken luteinizing hormone-releasing hormone-I (cLHRH-I) in the preoptic-hypothalamic region of the chicken.

To characterize a possible relationship between chicken luteinizing hormone-releasing hormone-I (cLHRH-I) and arginine-vasotocin (AVT) we performed immunocytochemical double-stainings throughout the preoptic-hypothalamic region of the chicken brain. This study clearly reveals a partial colocalization between both neuropeptides. Single-labeled neurons, containing either cLHRH-I or AVT are found intermingled with double stained cells, immunoreactive (ir) for both peptides. A significant number of double-labeled perikarya is found in the preoptic area, more specifically in the ventral and external portion of the supraoptic nucleus (SOv and SOe) and in the medial preoptic nucleus (MPOv). At the level of the anterior hypothalamus, double-labeled cells are predominantly observed near the third ventricle in the nucleus paraventricularis magnocellularis (PVN) and the nucleus periventricularis hypothalami (PHN). Next to this colocalization, a number of cLHRH-I-ir cell bodies are found in close apposition to AVT-ir fiber profiles in the very same areas. Taken together, these data are the first to provide morphological evidence indicating that the AVT system might be involved in the regulation of cLHRH-I release and thus of reproductive functions in birds.

Animals↗

Inducible nitric oxide synthase colocalizes with signs of lipid oxidation/peroxidation in human atherosclerotic plaques.

OBJECTIVE: Advanced human atherosclerotic plaques are characterized by the abundant presence of the autofluorescent non-soluble lipid pigment ceroid, consisting of oxidized lipoproteins. The aim of the present study was to examine the topographical and cellular distribution of inducible nitric oxide synthase (iNOS or NOS II) within different stages of atherosclerosis and its colocalization with ceroid deposits and nitrotyrosine. METHODS AND RESULTS: Different stages of atherosclerosis were studied by immunohistochemistry on whole-mount longitudinal sections of carotid endarterectomy specimens. In the adaptive intimal thickening the predominant cell type were smooth muscle cells. The fatty streaks contained both smooth muscle cells and macrophages with an extremely low NOS II immunoreactivity. The advanced atherosclerotic plaques however, showed a very dense infiltration by macrophages, of which a subpopulation expressed NOS II as a vesicular immunoreactivity in their cytoplasm. These were mainly present around the necrotic core, in association with ceroid accumulation and nitrotyrosine. Fluorescence quenching microscopy showed the presence of NOS II on autofluorescent ceroid vesicles in the macrophages. Large extracellular ceroid granules were not NOS II immunoreactive. NOS II mRNA was detected by RT-PCR and the protein by Western blot in the plaque tissue but not in mammary arteries used as controls. CONCLUSION: Ceroid, nitrotyrosine and NOS II colocalized in late stages of atherosclerosis and were found around the necrotic core in the plaque. This could suggest that NOS II expression in macrophages is involved in oxidation and peroxidation of lipids, leading to ceroid formation.

Aged↗

Pure antiandrogens disrupt the recruitment of coactivator GRIP1 to colocalize with androgen receptor in nuclei.

We have used confocal microscopy to elucidate the effects of antiandrogens on nuclear localization of the androgen receptor (AR) with its transcriptional coactivator GRIP1. We show that the agonist-activated AR recruits GRIP1 to colocalize with the receptor in the nucleoplasm. By contrast, AR complexed to the antiandrogens hydroxyflutamide and bicalutamide fails to influence nuclear distribution of GRIP1. Likewise, the non-steroidal antiandrogens prevent the agonist-induced AR-GRIP1 colocalization from occurring. Androgen antagonists affect nuclear redistribution of AR-GRIP1 in a fashion that parallels their effects on the transcriptional activity of AR, in that the pure antagonists block GRIP1-dependent activation of AR function, whereas the mixed antagonist/agonist cyproterone acetate promotes both AR-driven redistribution of GRIP1 and activation of AR by GRIP1.

Active Transport, Cell Nucleus↗

A receptor for advanced glycosylation endproducts (AGEs) is colocalized with neurofilament-bound AGEs and SOD1 in motoneurons of ALS: immunohistochemical study.

Neurofilament (NF)-bound AGEs colocalize immunochemically with SOD1 in the motoneurons of patients with ALS. Among three types of AGE receptors reported in the human brain, AGE-R1 (oligosaccharyltransferase family) and AGE-R2 (substrate of protein kinase C) have been found in neurons, while AGE-R3 is restricted to glia. The present study investigates which of these receptors may be responsible for binding AGEs in the NF conglomerates of motoneurons. Immunostaining of paraffin sections from eight ALS patients (five sporadic and three familial) and three control cases was performed with antibodies directed against R1 and R2, in parallel with those against AGEs and SOD1. The sites of AGE-R1 immunoreactivity (IR) in motoneurons were in conformity to those of NF-associated AGE and SOD1 IRs. By contrast, the IR of R2 was negative in NF conglomerates. Negative R2 IR for NF conglomerates was outlined by surrounding coarse R2 immunopositive granules in the perikaryon. No IR for R1 or R2 was found in hyaline or Bunina inclusions. There was no extraneuronal expression of IR for AGE-R1 or AGEs in microglia or astroglia around the NF accumulation. The colocalization of AGE, AGE-R1, and SOD1 at NF conglomerates in motoneurons supports the notion that AGE-mediated oxidative stress and protein aggregation may be implicated in NF conglomeration and ALS pathogenesis.

Amyotrophic Lateral Sclerosis↗

A quantitative model suggests immune memory involves the colocalization of B and Th cells.

A prominent and essential feature of the humoral immune response of vertebrates is immunologic memory: the ability to recall previous exposure to antigen. We present a mathematical model of the growth and interactions of the major cell populations involved in the humoral immune response. Our analysis of this model predicts that the formation of a dynamic association between small numbers of antigen-specific B and Th cells, "colocalization", is sufficient to account for memory and the kinetics of the secondary response--neither specifically differentiated Th or B memory cells nor networks of antigen and anti-idiotypes are required. The colocalization hypothesis explains a number of existing experimental observations and can be tested by straightforward experiments which we describe.

Animals↗

Colocalization of nitric oxide synthase with vasoactive intestinal peptide, neuropeptide Y, and tyrosine hydroxylase in nerves supplying the human ureter.

The distribution and patterns of colocalization of nitric oxide synthase (NOS), vasoactive intestinal peptide (VIP), neuropeptide Y (NPY) and the catecholamine-synthesizing enzyme tyrosine hydroxylase (TH) were examined in nerve fibers supplying the human lower ureter using double label immunofluorescence. Many nerve fibers immunoreactive for NOS were observed within the ureter. Positive varicose fibers were seen running longitudinally within the smooth muscle bundles, particularly those of the inner layers of the ureter. Immunoreactive axons were also prominent within the subepithelium, and as plexi surrounding many blood vessels. The colocalization studies indicated that NOS was never present in presumptive sympathetic nerve fibers expressing TH. All fibers containing VIP, however, were also immunoreactive for NOS. In addition, a minor population of NOS fibers did not contain VIP. Neuropeptide Y coexisted with NOS in a significant number of nerve terminals, although fibers expressing only NPY were equally common. Several immunochemically distinct nerve populations can therefore be distinguished in the human ureter: (1) nerves containing NOS either with or without VIP; (2) NOS-immunoreactive fibers with NPY; and (3) those fibers expressing TH or NPY which do not contain NOS. The results indicate that some non-noradrenergic peptide-containing nerves in the human ureter have the capacity to synthesize nitric oxide (NO), and that NO may be involved in the regulation of ureteric motility.

Aged↗

Nitrergic neurons in the pancreas of newborn guinea pig: their distribution and colocalization with various neuropeptides and dopamine-beta-hydroxylase.

The distribution of nitrergic neurons in the pancreas of the newborn guinea pig was first investigated, using nitric oxide synthase (NOS) immunofluorescence and nicotinamide adenine dinucleotide hydrogen phosphate-diaphorase (NADPH-d) histochemistry. There was total colocalization of NOS and NADPH-d in the pancreatic ganglion cells. NADPH-d was then used as a marker for NOS. In the whole mount preparation of the pancreas, most of the nitrergic neurons were located in the head and the body region, along the branches of pancreatic blood vessels. Some were also associated with the main pancreatic duct, islets of Langerhans and pancreatic acini. To investigate whether NADPH-d stained cells were neurons and whether NADPH-d was colocalized with various neuropeptides and dopamine-beta-hydroxylase (D beta H), an enzyme involved in the synthesis of noradrenaline, antibodies against neuron specific enolase (NSE), vasoactive intestinal peptide (VIP), neuropeptide Y (NPY). D beta H, substance P (SP), calcitonin gene-related peptide (CGRP) and bombesin (BOM) were used. Of all NSE positive ganglion cells, 76.8% were NADPH-d positive. NOS, VIP, NPY and D beta H immunoreactivities were found in both the neuronal cell bodies and nerve fibres in the pancreas while SP, CGRP and BOM immunoreactivities were detected only in the nerve fibres. SP-, CGRP- and BOM-containing nerves were in close contact with both NADPH-d positive as well as NADPH-d negative neurons. The percentages of NADPH-d/VIP, NADPH-d/NPY, NADPH-d/D beta H neurons in the total number of pancreatic neurons were 67.4%, 53.5%, 21.5% respectively. With double labelling in adjacent sections three subpopulations of pancreatic ganglion cells were demonstrated: NADPH-d/VIP/NPY, NADPH-d/VIP/D beta H and NADPH-d/NPY/D beta H.

Animals↗

Plasmodium yoelii YM MAEBL protein is coexpressed and colocalizes with rhoptry proteins.

We have previously cloned genes from multiple rodent malaria species exhibiting characteristics of the genes encoding Duffy binding like-erythrocyte binding proteins (DBL-EBP). Homology is seen in the intron/exon structure of the genes and in the carboxyl terminal region (including the deduced carboxyl cysteine-rich domain) of the proteins they encode. However, the amino termini of these proteins are not homologous to the DBL-EBP but contain tandem cysteine-rich regions that are similar to the cysteine-rich region of AMA-1 (apical membrane antigen-1), a rhoptry protein. This new family of proteins has been termed MAEBL and these are paralogues of both AMA-1 and the DBL-EBP. Serum against the carboxyl cysteine-rich region of the Plasmodium yoelii YM MAEBL reacted to parasites with a punctate fluorescence pattern characteristic of apical organelle proteins and also localized MAEBL to the surface of merozoites within schizonts. This antiserum immunoprecipitated a protein doublet (120/128 kDa) that was unexpectedly insoluble when compared to members of the DBL-EBP. Characterization of MAEBL was extended through colocalization studies comparing the P. yoelii YM MAEBL to other parasite proteins. This protein appeared to be located in the rhoptry organelles as it colocalized with both AMA-1 and the P. yoelii 235 kDa rhoptry proteins within parasites. In addition, MAEBL is expressed relatively early in schizont development and appears on the merozoite surface after segmentation. Both the pattern and time of expression of the P. yoelii YM MAEBL are consistent with a rhoptry rather than a microneme protein.

Animals↗

GLP-1 and GIP are colocalized in a subset of endocrine cells in the small intestine.

BACKGROUND: The incretin hormones GIP and GLP-1 are thought to be produced in separate endocrine cells located in the proximal and distal ends of the mammalian small intestine, respectively. METHODS AND RESULTS: Using double immunohistochemistry and in situ hybridization, we found that GLP-1 was colocalized with either GIP or PYY in endocrine cells of the porcine, rat, and human small intestines, whereas GIP and PYY were rarely colocalized. Thus, of all the cells staining positively for either GLP-1, GIP, or both, 55-75% were GLP-1 and GIP double-stained in the mid-small intestine. Concentrations of extractable GIP and PYY were highest in the midjejunum [154 (95-167) and 141 (67-158) pmol/g, median and range, respectively], whereas GLP-1 concentrations were highest in the ileum [92 (80-207) pmol/l], but GLP-1, GIP, and PYY immunoreactive cells were found throughout the porcine small intestine. CONCLUSIONS: Our results provide a morphological basis to suggest simultaneous, rather than sequential, secretion of these hormones by postprandial luminal stimulation.

Animals↗

Colocalization on the same synaptic vesicles of syntaxin and SNAP-25 with synaptic vesicle proteins: a re-evaluation of functional models required?

Synaptic vesicle docking and calcium dependent exocytosis are thought to require the specific interaction of proteins of the synaptic vesicle membrane (such as VAMP/synaptobrevin and synaptotagmin) and their plasma membrane-located counterparts (such as syntaxin and SNAP-25). When isolating synaptic vesicles by glycerol velocity gradient centrifugation we found cosedimentation of the presumptive presynaptic plasma membrane proteins syntaxin and SNAP-25 with synaptic vesicle membrane proteins. In order to further identify the antibody binding organelles we performed an immunoelectron microscopical analysis of synaptosomal profiles. Syntaxin and SNAP-25 were not only associated with the plasma membrane but to a large extent also with synaptic vesicle profiles. In order to answer the question whether the syntaxin and SNAP-25 containing vesicular compartment would also carry classical synaptic vesicle membrane markers we performed double labeling experiments using poly- and monoclonal antibodies. We found colocalization on the same vesicle not only of SNAP-25 and syntaxin but also of SNAP-25 with the synaptic vesicle membrane proteins SV2 and synaptotagmin and of syntaxin with the vesicular membrane protein synaptophysin. Our results demonstrate that syntaxin and SNAP-25 are colocalized with classical vesicle membrane proteins on the same vesicle and suggest that the functional models for the interaction of presynaptic proteins need to be re-evaluated.

Animals↗

Surface redistribution of interferon gamma-receptor and its colocalization with the actin cytoskeleton.

BACKGROUND: Specific antibodies for human IFN gamma-R1 were used to examine its mobilization in Colo 205 cells. METHODS: We report here that antibody-IFN gamma-R1 complex induced capping and actin colocalization. Pretreatment with cytochalasin D abolished this capping. To define the role of the IFN gamma-R1 in the possible interaction with actin, transfected murine fibroblasts cell line with human cDNA IFN gamma-R1 were used. RESULTS: Only those cells expressing the full receptor and cultured in suspension polarized the receptor and this colocalized with actin filaments. Nevertheless, cells truncated in their intracellular domain displayed no capping and actin remained unaltered either in suspension or in monolayer culture conditions. A mutant bearing an IFN gamma-R1 with substitutions in positions 270-271 of the intracellular domain redistributed both IFN gamma-R1 and actin as micropatches instead of capping. Mutation in 256-303 residues resulted in IFN gamma-R1 microaggregates but actin remained unchanged. CONCLUSIONS: These experimental models allowed us to highlight an apparent receptor-microfilament association through the intracellular domain of IFN gamma-R1, and to specifically locate it within the intracellular region 256-303 that has been identified as relevant for ligand-receptor internalization and biological function.

Actins↗

Colocalization of NO and VIP in neurons of the submucous plexus in the rat intestine.

Since very few previous studies have carried out the quantitative analysis for the colocalization of nitric oxide (NO) and vasoactive intestinal peptide (VIP) in the submucous neurons in the rat digestive tract, we applied in vivo treatment of colchicine to enhance the immunoreactivity and examined the colocalization of NO synthase (nNOS) and VIP in neurons of the submucous plexus throughout the rat digestive tract. The density of nNOS-containing neurons in the submucous plexus in the stomach corpus (103+/-25 cells/cm(2), n=3) and that in the antrum (157+/-9 cells/cm(2), n=3) were significantly lower than those in small and large intestine. However no difference was detected in the cell density among duodenum (1967+/-188 cells/cm(2), n=3), jejunum (2640+/-140 cells/cm(2), n=3), ileum (2070+/-42 cells/cm(2), n=3), proximal colon (2243+/-138 cells/cm(2), n=3) and distal colon (2633+/-376 cells/cm(2), n=3). The proportion of nNOS-immunoreactive (IR), nNOS/VIP-IR and VIP-IR neurons to the total number of submucous neurons was examined. nNOS/VIP-IR neurons comprised 45-55% of total number of submucous neurons from the duodenum to the proximal colon, however those comprised 66.4+/-5.1% in the distal colon. The results showed that the dense distribution of nNOS-containing neurons was found in the submucous plexus throughout the small and large intestine, and large population of submucous neurons co-stored nNOS and VIP.

Animals↗

PACAP colocalizes with luteinizing and follicle-stimulating hormone immunoreactivities in the anterior lobe of the pituitary gland.

Pituitary adenylate cyclase activating polypeptide (PACAP) and its close relative vasoactive intestinal polypeptide (VIP) were demonstrated in the anterior pituitary gland. The cells which exhibited PACAP immunoreactivity were oval or round shaped. Their distribution was similar to that of gonadotropes but the number of PACAP immunoreactive cells was less. Double labeling revealed that PACAP immunoreactivity partially colocalized with luteinizing and follicle-stimulating hormone; however, colocalization with other pituitary hormone immunoreactivities was not demonstrated. Our results suggest an autocrine or paracrine role of PACAP in the regulation of pituitary functions.

Animals↗