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Results for “Colocalization”

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PubMed1999

Hsp47-dependent and -independent intracellular trafficking of type I collagen in corneal endothelial cells.

PURPOSE: Type I collagen is post-translationally regulated in corneal endothelial cells (CEC): CEC synthesize procollagen I and degrade it intracellularly. We investigated whether there is a Hsp47-independent pathway during intracellular trafficking of procollagen I. METHODS: Specific inhibitors were used to block intracellular transport of procollagen I and Hsp47. Immunocytochemical analysis was performed to determine the intracellular localization of the proteins of interest. RESULTS: When cells were treated with alpha,alpha'-dipyridyl, this specific inhibitor for collagen promoted retention in the endoplasmic reticulum (ER) of some of the underhydroxylated procollagen I, which was colocalized with Hsp47 in CEC. At the same time, another fraction of the alpha,alpha'-dipyridyl-induced underhydroxylated procollagen I was not located in the ER. When CEC were treated with brefeldin A, procollagen I and Hsp47 demonstrated a high degree of colocalization at the ER, whereas the inhibitor had less of an effect on the compartmentalization of procollagen I and prolyl 4-hydroxylase. When CEC were treated with either monensin or bafilomycin A1, procollagen I and Hsp47 were not colocalized: procollagen I was mostly localized at the Golgi area, while Hsp47 predominantly showed ER distribution. When colocalization of procollagen I and prolyl 4-hydroxylase was examined, a major population of procollagen I was not colocalized with prolyl 4-hydroxylase in the ER. CONCLUSIONS: These results indicate that some procollagen I and Hsp47 travel together from the ER to the cis-Golgi compartment and that a major population of procollagen I that may not be properly hydroxylated may be destroyed intracellularly via the Hsp47-independent pathway in CEC.

2,2'-Dipyridyl↗

PubMed2000

Localization of the murine Niemann-Pick C1 protein to two distinct intracellular compartments.

Niemann-Pick type C (NPC) disease is characterized by an accumulation of cholesterol and other lipids in the lysosomal compartment. In this report, we use subcellular fractionation and microscopy to determine the localization of the murine Niemann-Pick C1 (NPC1) protein. Fractionation of mouse liver homogenates indicates that some NPC1 cosediments with lysosome-associated membrane protein 1 (LAMP1)-containing membranes. However, a significant amount of NPC1 is also found in membranes that do not contain LAMP1. Moreover, fractionation of liver membranes and fibroblasts in the presence of a nonionic detergent showed that a fraction of NPC1 cosediments with caveolin-1 in rafts. Immunofluorescence microscopy of cultured mouse fibroblasts showed that NPC1 is found in two morphologically distinct structures. The first population is characterized by large punctate structures that do not colocalize with major organelle protein markers, but do colocalize with filipin and a small fraction of caveolin-1. Examination of these large NPC1-containing compartments using electron microscopy shows that these structures contain extensive internal membranes. The second population is represented by smaller, more diffuse structures, a fraction of which colocalize with LAMP1-positive compartments. Incubation of fibroblasts with low density lipoprotein (LDL) increases colocalization of NPC1 with LAMP1-containing compartments. This colocalization can be further enhanced by treating fibroblasts with progesterone or chloroquine. The results indicate that NPC1 is associated with an unique vesicular compartment enriched with cholesterol and containing caveolin-1, and that NPC1 cycles to LAMP1-positive compartments, presumably to facilitate the processing of LDL-derived cholesterol.

Amino Acid Sequence↗

PubMed2002

Activation of membrane-type matrix metalloproteinase 3 zymogen by the proprotein convertase furin in the trans-Golgi network.

Matrix metalloproteinases (MMPs), a family of zinc-dependent endopeptidases implicated in tumor invasion and metastasis, must undergo zymogen activation prior to expressing any proteolytic activity. Although the cysteine-switch model predicts the well-established autoactivation process, approximately 40% of the known MMPs possess a conserved RXKR motif between their pro- and catalytic domains and, thus, could be activated directly by members of the proprotein convertase family. To further understand this process, we analyzed the activation of proMT3-MMP as a model system. We demonstrated that the conversion of MT3-MMP zymogen into active form is dependent on both the furin-type convertase activity and the R(116)RKR motif. Consistently, MT3-MMP was colocalized with furin in the trans-Golgi network by confocal microscopy. However, neither furin activity nor its recognition site in MT3-MMP is required for the observed colocalization. In fact, the colocalization pattern remains intact, even in the presence of brefeldin A, an agent known to block endoplasmic reticulum to Golgi trafficking. Yet, brefeldin A completely blocked the activation of MT3-MMP. A23187, a calcium ionophore known to block furin maturation, also blocked proMT3-MMP activation but had minimal effect on the colocalization between MT3-MMP and furin. Thus, furin processes MT3-MMP zymogen in the trans-Golgi network, where they colocalize independently of their apparent enzyme-substrate relationship.

Amino Acid Sequence↗

PubMed1992

Immunohistochemical analysis of GH-producing adenomas--with special emphasis on plurihormonality of individual tumor cells by double staining.

Forty-four human growth hormone (GH)-producing adenomas were investigated immunohistochemically for the concomitant localization of GH, prolactin (PRL), and glycoprotein hormone alpha subunit. Immunoreactivity for GH, PRL, and the alpha subunit was found in 44, 37, and 36 cases, respectively. By double immunohistochemical staining, 24 of 27 cases showed colocalization of GH and alpha subunit, with the numbers of tumor cells showing double staining varying from case to case. The colocalization of GH and alpha subunit was noted in some normal pituitary cells. In adenoma cells, the colocalization of GH and PRL, and PRL and alpha subunit, was observed in 9 and 12 cases, respectively. The normal pituitary gland showed only occasional colocalization of GH and PRL, or PRL and alpha subunit. We found that GH-producing adenomas are plurihormonal at the individual tumor cell level, with coexpression of GH-alpha subunit, GH-PRL, and PRL-alpha subunit. The colocalization of GH and alpha subunit may be an expression of a subpopulation of normal anterior pituitary cells (with GH-alpha subunit coexpression), but the more frequent coexpression of GH-PRL may be pathological, accompanying tumorigenesis of the anterior pituitary cells, in which a pituitary-specific transcriptional factor, pit-1, may play a role.

Adenoma↗

PubMed2005

Direct action of platelet activating factor (PAF) induces eosinophil accumulation and enhances expression of PAF receptors in conjunctivitis.

PURPOSE: The goal of the present study was to investigate the role of platelet activating factor (PAF) and PAF receptor (PAF-R) in the recruitment of eosinophils into the conjunctiva in the course of PAF induced conjunctivitis. Eosinophils are important players in the immediate hypersensitivity reactions and in allergic conjunctivitis. PAF-R is expressed in many ocular tissues including conjunctival cells. Although it is known that PAF is one of the most potent chemotactic agents for the recruitment of eosinophils, factors responsible for it in conjunctivitis are not clear. Colocalization analysis has been employed to quantify the degree of colocalization of major basic protein (MBP) and PAF-R antigens in the course of PAF induced conjunctivitis. METHODS: A 1% solution of PAF was applied in eye drops to male Brown Norway rats. Eyes were harvested with intact conjunctivas at different time points and examined using histology, immunohistochemistry, confocal immunofluorescence microscopy, and reverse transcription-polymerase chain reaction. PAF-R and MBP (a marker of eosinophils) antibodies have been used for immunohistochemical studies. Quantitative analysis of the colocalization of PAF-R and major basic protein (MBP) antigens was performed. RESULTS: Instillation of PAF caused a time dependent recruitment of eosinophils. Eosinophils revealed PAF-R in the intact state. An influx of eosinophils into the conjunctiva was caused by the interaction of PAF with PAF-R and, possibly, with MBP antigen. PAF appeared to enhance the expression of PAF-R by eosinophils and to act toward the PAF-R directly, without chemokine mediation. CONCLUSIONS: Quantitative colocalization analysis helped to determine that the recruitment of eosinophils in PAF induced conjunctivitis is accomplished via direct action of PAF toward the PAF-R. It also ensured an objective evaluation of the changes of the degree of colocalization of MBP and PAF-R antigens and the degree of PAF-R expression in dynamics, the findings not otherwise obtainable using qualitative approaches alone.

Animals↗

PubMed2006

Differential trafficking and desensitization of human ET(A) and ET(B) receptors expressed in HEK 293 cells.

Endothelin-1 (ET-1) is a vasoconstrictor peptide that acts on ET(A) and ET(B) receptors on smooth muscle cells (SMCs). Because vascular SMCs can express both receptors, it is difficult to study the localization and properties of each subtype. Therefore, we investigated the localization and function of ET(A) and ET(B) receptors transfected into HEK 293 cells. Immunocytochemistry was used to examine colocalization of ET receptors with the plasma membrane marker, pan cadherin. In cells transfected with ET(A) receptors, 83 +/- 2% of these receptors colocalized with pan cadherin. In ET(B) receptor-transfected cells, 54 +/- 2% of the receptor colocalized with pan cadherin. When ET(A) and ET(B) receptors were cotransfected, 97 +/- 1% of ET(B) receptors colocalized with ET(A) receptors and 84 +/- 2% of ET(B) receptors colocalized with pan cadherin. ET-1 and sarafotoxin 6c (S6c, ET(B) receptor agonist) increased [Ca2+]i in cells transfected with ET(A) or ET(B) receptors; 100 nM of ET-1 and S6c caused maximal responses. When stimulated with ET-1, ET(B) receptors desensitized faster (t(1/2) = 21 +/- 1 sec) than ET(A) receptors (t(1/2) = 48 +/- 1 sec). S6c-induced increases in [Ca2+]i desensitized in cells expressing ET(B) receptors only (t(1/2) = 17 +/- 1 s). Desensitization was eliminated in cells cotransfected with ET receptors. We conclude that ET(A) receptors localize to the cell membrane, whereas ET(B) receptors are in the membrane and intracellular compartments. Coexpressed ET receptors are in the membrane. ET(B) receptors desensitize faster than ET(A) receptors, but receptor coexpression eliminates desensitization. Finally, ET(A) and ET(B) receptors interact to change receptor trafficking which may modify ET receptor function in vascular SMCs coexpressing these receptors.

Calcium↗

PubMed2026

Spatially Contextualized Integrative Genomics Highlights Neuronal and Glial Regulatory Programs in Low Back Pain.

PURPOSE: Low back pain (LBP) is a heterogeneous pain condition with a measurable genetic contribution, but the genes, brain cell types, and spatial tissue contexts through which inherited risk is expressed remain unclear. We aimed to define cell-type-specific and spatially contextualized genetic mechanisms underlying LBP. METHODS: FinnGen R12 LBP GWAS summary statistics (42,521 cases and 353,224 controls) were integrated with brain single-nuclei eQTL data across eight major brain cell classes. We evaluated genome-wide polygenic signal using LDSC, prioritized genes using MAGMA and PoPS, and performed brain cell-type-specific eQTL-anchored Mendelian randomization, primarily based on single-instrument Wald ratio estimates, followed by Bayesian colocalization. Spatial genetic mapping was conducted using gsMap in an E16.5 murine embryonic atlas and two adult human lumbar spinal cord Visium sections. Selected candidates were assessed by RT-qPCR in neuronal-like and astroglial-like inflammatory cell models. RESULTS: LDSC supported interpretable polygenic signal for LBP. MAGMA and PoPS showed partial gene-level convergence, with TCF4 and TMEFF2 supported by both approaches. Across 1641 tested gene-cell type exposures, significant eQTL-anchored MR associations were concentrated in excitatory neurons, oligodendrocytes, inhibitory neurons, and astrocytes. Integrated eQTL-anchored MR, colocalization, and gene-prioritization evidence highlighted CLEC18A, QPRT, and GMPPB as higher-priority non-MHC candidates with moderate, but not strong, colocalization support. gsMap localized LBP-associated enrichment to neuroaxis-related embryonic regions, including brain, spinal cord, sympathetic nerve, and dorsal root ganglion, and to neuronal-like niches in adult lumbar spinal cord. RT-qPCR showed model-dependent expression changes, with QPRT and LGI4 preferentially responsive in neuronal-like SH-SY5Y cells and GMPPB and DPYSL5 responsive in astroglial-like U251 cells. CONCLUSION: These findings support neuronal and glial regulatory programs as plausible contributors to LBP genetic susceptibility and highlight CLEC18A, QPRT, and GMPPB as higher-priority non-MHC candidates with moderate colocalization support. The results provide a spatially contextualized framework for candidate prioritization in LBP, while emphasizing the need for larger cell-type-specific eQTL resources and functional validation before therapeutic or mechanistic conclusions can be drawn.

Mendelian randomization↗

PubMed1996

Acidic fibroblast growth factor mRNA is expressed by basal forebrain and striatal cholinergic neurons.

Evidence for the importance of the basal forebrain cholinergic system in the maintenance of cognitive function has stimulated efforts to identify trophic mechanisms that protect this cell population from atrophy and dysfunction associated with aging and disease. Acidic fibroblast growth factor (aFGF) has been reported to support cholinergic neuronal survival and has been localized in basal forebrain with the use of immunohistochemical techniques. Although these data indicate that aFGF is present in regions containing cholinergic cell bodies, the actual site of synthesis of this factor has yet to be determined. In the present study, in situ hybridization techniques were used to evaluate the distribution and possible colocalization of mRNAs for aFGF and the cholinergic neuron marker choline acetyltransferase (ChAT) in basal forebrain and striatum. In single-labeling preparations, aFGF mRNA-containing neurons were found to be codistributed with ChAT mRNA+ cells throughout all fields of basal forebrain, including the medial septum/diagonal band complex and striatum. By using a double-labeling (colormetric and isotopic) technique, high levels of colocalization (over 85%) of aFGF and ChAT mRNAs were observed in the medial septum, the diagonal bands of Broca, the magnocellular preoptic area, and the nucleus basalis of Meynert. The degree of colocalization was lower in the striatum, with 64% of the cholinergic cells in the caudate and 33% in the ventral striatum and olfactory tubercle labeled by the aFGF cRNA. These data demonstrate substantial regionally specific patterns of colocalization and support the hypothesis that, via an autocrine mechanism, aFGF provides local trophic support for cholinergic neurons in the basal forebrain and the striatum.

Animals↗

PubMed1999

Immunohistochemical localization of delta opioid receptors in peripheral tissues.

The distribution of delta opioid receptor (DOR) immunoreactivity (ir) was examined in various peripheral tissues of Sprague-Dawley rats and macaque monkeys, including glabrous and hairy skin, corneas, eyelids, and the lip. DOR-ir was observed in all tissues examined. In addition to the presence of DOR-immunoreactive fibers in subcutaneous nerve bundles and the papillary dermis, we report the existence of positively labeled fibers and terminals in close association with peripheral structures not traditionally assigned a primarily nociceptive function, such as hair follicles, glandular apparatus, and blood vessels. In every case, staining was restricted to small-diameter axons that appeared to terminate as free nerve endings. To further classify DOR-immunoreactive fibers, we examined the extent of colocalization between DOR and three commonly used neuronal subtype markers; tyrosine hydroxylase (TH), calcitonin gene-related peptide (CGRP), and RT-97, a monoclonal antibody which preferentially labels neurons with myelinated axons. Additional double-labeling experiments using the nonspecific neuronal marker Protein Gene Product 9.5 were performed in glabrous skin to determine the percentage of total fiber count that displayed DOR-ir. No colocalization was observed between DOR and RT-97, indicating that DOR-ir is localized to unmyelinated axons. In addition, DOR colocalized with CGRP, but did not colocalize with TH. Taken together, these data support the hypothesis that delta opioid receptors in peripheral tissues are associated with sensory fibers, but not with the terminals of postganglionic sympathetic neurons.

Animals↗

PubMed2000

NPY immunoreactivity in endocrine cells of duck pancreas: an ontogenetic study.

In the literature, neuropeptide Y (NPY) has been described in the brain and peripheral nerves. More recently, it has also been detected in endocrine cells of hamster, embryonic mouse, and rat pancreas. However, the presence of NPY in avian embryos and the possible colocalization of this peptide with the other pancreatic hormones have not been reported previously. In this study, NPY presence was studied by immunocytochemical methods in the endocrine pancreas of domestic duck during pre- and postnatal development. NPY immunoreactivity (IR) was detected in embryos and adult animals. Around hatching the intensity of IR in endocrine cells decreased. Double immunohistochemical staining revealed that: 1) NPY-IR is extensively colocalized in small and mixed islets with insulin-IR both in embryos and in adults; and 2) in early embryos NPY-IR occasionally colocalized with glucagon and somatostatin. In early embryos, the colocalization of NPY-IR with several pancreatic hormones could be related to the presence of multi-hormonal progenitor cells. The close relation between insulin and NPY, both in embryos and adults, led us to hypothesize a key role for NPY on insulin cells of duck pancreas.

Age Factors↗

PubMed2000

Immunostaining of ganglioside GD1b, GD3 and GM1 in rat cerebellum: cellular layer and cell type specific associations.

We have studied the cellular distribution of gangliosides GD1b, GD3 and GM1 in rat cerebellum by immunostaining, using monoclonal antibodies and confocal microscopy. Antibodies against astroglial, neuronal and synaptic vesicle associated molecules were used for colocalization analyses. In the gray matter, the anti-GD1b antibody stained thin strands in the molecular layer (ML), interpreted as Bergman glia fibers based on colocalized staining with anti-glial fibrillary acidic protein (GFAP). The neuropil in the granule (GL) and Purkinje (PL) cell layers was also anti-GD1b positive. The anti-GD3 antibody stained the ML, the neuropil in the GL and PL and also the granule and Purkinje cell bodies, appearing intracytoplasmically and vesicle associated. Anti-GD1b and anti-GD3 staining in the GL glomeruli were colocalized with anti-synaptophysin staining. The anti-GM1 antibody stained cell bodies in the ML but they could not be characterized in colocalization experiments. The GL and PL were not stained with the anti-GM1 antibody. In the white matter, different staining patterns were seen for the gangliosides, the anti-GM1 staining being the most intense. This study shows cellular layer and cell type specific associations of the investigated gangliosides and localization of GD1b and GD3 at synaptic sites, warranting further studies on their role in synaptic mechanisms.

Animals↗

PubMed2004

Anatomical evidence for transsynaptic influences of estrogen on brain-derived neurotrophic factor expression.

Several studies have demonstrated that estrogen modulates brain-derived neurotrophic factor (BDNF) mRNA and protein within the adult hippocampus and cortex. However, mechanisms underlying this regulation are unknown. Although an estrogen response element (ERE)-like sequence has been identified within the BDNF gene, such a classical mechanism of estrogen-induced transcriptional activation requires the colocalized expression of estrogen receptors within cells that produce BDNF. Developmental studies have demonstrated such a relationship, but to date no studies have examined colocalization of estrogen receptors and BDNF within the adult brain. By utilizing double-label immunohistochemistry for BDNF, estrogen receptor-alpha (ER-alpha), and estrogen receptor-beta (ER-beta), we found only sparse colocalization between ER-alpha and BDNF in the hypothalamus, amygdala, prelimbic cortex, and ventral hippocampus. Furthermore, ER-beta and BDNF do not colocalize in any brain region. Given the recent finding that cortical ER-beta is almost exclusively localized to parvalbumin-immunoreactive GABAergic neurons, we performed BDNF/parvalbumin double labeling and discovered that axons from cortical ER-beta-expressing inhibitory neurons terminate on BDNF-immunoreactive pyramidal cells. Collectively, these findings support a potential transsynaptic relationship between estrogen state and cortical BDNF: By directly modulating GABAergic interneurons, estrogen may indirectly influence the activity and expression of BDNF-producing cortical neurons.

Amygdala↗

PubMed2004

Synaptic localization of P2X7 receptors in the rat retina.

The distribution of P2X(7) receptor (P2X(7)R) subunits was studied in the rat retina using a subunit-specific antiserum. Punctate immunofluorescence was observed in the inner and outer plexiform layers. Double labeling of P2X(7) and the horizontal cell marker, calbindin, revealed extensive colocalization in the outer plexiform layer (OPL). Significant colocalization of P2X(7)R and kinesin, a marker of photoreceptor ribbons, was also observed, indicating that this receptor may be expressed at photoreceptor terminals. Furthermore, another band of P2X(7)R puncta was identified below the level of the photoreceptor terminals, adjacent to the inner nuclear layer (INL). This band of P2X(7)R puncta colocalized with the active-zone protein, bassoon, suggesting that "synapse-like" structures exist outside photoreceptor terminals. Preembedding immunoelectron microscopy demonstrated P2X(7)R labeling of photoreceptor terminals adjacent to ribbons. In addition, some horizontal cell dendrites and putative "desmosome-like" junctions below cone pedicles were labeled. In the inner plexiform layer (IPL), P2X(7)R puncta were observed surrounding terminals immunoreactive for protein kinase C-alpha, a marker of rod bipolar cells. Double labeling with bassoon in the IPL revealed extensive colocalization, indicating that P2X(7)R is likely to be found at conventional cell synapses. This finding was confirmed at the ultrastructural level: only processes presynaptic to rod bipolar cells were found to be labeled for the P2X(7)R, as well as other conventional synapses. These findings suggest that purines play a significant role in neurotransmission within the retina, and may modulate both photoreceptor and rod bipolar cell responses.

Animals↗

PubMed2006

Immunohistochemical localization of calbindin-D28k and calretinin in the spinal cord of Xenopus laevis.

Immunohistochemical techniques were used to investigate the distribution and morphology of neurons containing the calcium-binding proteins calbindin-D28k (CB) and calretinin (CR) in the spinal cord of Xenopus laevis and determine the extent to which this organization is comparable to that of mammals. Most CB- and CR-containing neurons were located in the superficial dorsal gray field, but with distinct topography. The lateral, ventrolateral, and ventromedial fields also possessed abundant neurons labeled for either CB or CR. Double immunohistofluorescence demonstrated that a subpopulation of dorsal root ganglion cells and neurons in the dorsal and ventrolateral fields contained CB and CR. By means of a similar technique, a cell population in the dorsal field was doubly labeled only for CB and nitric oxide synthase (NOS), whereas in the ventrolateral field colocalization of NOS with CB and CR was found. Choline acetyltransferase immunohistochemistry revealed that a subpopulation of ventral horn neurons, including motoneurons, colocalized CB and CR. The involvement of CB- and CR-containing neurons in ascending spinal projections was demonstrated combining the retrograde transport of dextran amines and immunohistochemistry. Cells colocalizing the tracer and CB or CR were quite numerous, primarily in the dorsal and ventrolateral fields. Similar experiments demonstrated supraspinal projections from CB- and CR-containing cells in the brainstem and diencephalon. The distribution, projections, and colocalization with neurotransmitters of the neuronal systems containing CB and CR in Xenopus suggest that CB and CR are important neuromodulator substances with functions conserved in the spinal cord from amphibians through mammals.

Animals↗

PubMed2002

Proteasome dynamics during cell cycle in rat Schwann cells.

The proteasome is responsible for most of the protein degradation that takes place in the cytoplasm and nucleus. Immunofluorescence and electron microscopy are used to study proteasome dynamics during the cell cycle in rat Schwann cells. During interphase, the proteasome is present in the nucleus and cytoplasm and shows no colocalization with cytoskeletal components. Some cytoplasmic proteasomes always localize in the centrosome both in interphase and in mitotic cells and only associate with microtubules during mitosis. The proteasome exits the nucleus during prophase. In anaphase, the proteasome becomes prominent in the region between the two sets of migrating chromosomes and in association with interzonal microtubules and stem bodies. In telophase, the proteasome begins to reenter the nucleus and is prominent in the midbody region until the end of cytokinesis. The proteasome does not colocalize with actin or vimentin during mitosis, except for colocalization with actin in the sheet-like lamellipodia, which serve as substrate attachments for the cell during mitosis. During S phase, nuclear proteasomes colocalize with foci of BrdU incorporation, but this association changes with time: maximal at early S phase and declining as S phase progresses to the end. These results are discussed in relation to the biochemical pathways involved in cell cycle progression.

Active Transport, Cell Nucleus↗

PubMed2002

Adrenomedullin as a pancreatic hormone.

Adrenomedullin (AM) is a multiregulatory peptide which is expressed in a wide range of tissues. In the pancreas, AM was first found in mammals, including man, and its colocalization with the pancreatic polypeptide (PP) was established in islet F cells. In addition, three different AM receptors have been characterized in B-cells. AM has been also located in the pancreatic cells of other vertebrate classes. The frequency and distribution of AM cells vary between different animals; they can be found scattered among the exocrine tissue, in the islets, or in ductal epithelia. The colocalization of AM with other hormones presents different patterns, although in birds, as in mammals, it seems to colocalize only with PP. The best-determined pancreatic AM function is the inhibition of insulin secretion in B-cells, which seems to be linked to a recently discovered binding protein, factor H. In relation to this physiological role, clinical data show that AM is raised in some groups of both types I and II diabetic patients and AM might have triggered the disease in a subset of them. On the other hand, AM pancreatic cells are also involved in the response to septic shock by increasing AM circulating levels. A third putative function is the inhibition of amylase secretion by the exocrine pancreatic cells. AM has been found in embryonic mammalian pancreas from the earliest stages of the development, colocalizing with all pancreatic hormones, although in adults only coexpression with PP is kept. AM may play a role in the growth and morphogenesis of the pancreas.

Adrenomedullin↗

PubMed2005

Changes in neuronal protein 22 expression and cytoskeletal association in the alcohol-dependent and withdrawn rat brain.

The action of alcohol on neuronal pathways has been an issue of increasing research focus, with numerous findings contradicting the previously accepted idea that its effect is nonspecific. The human NP22 (hNP22) gene was revealed by its elevated expression in the frontal cortex of the human alcoholic. The sequences of hNP22 and the rat orthologue rNP22 contain a number of domains consistent with those of cytoskeletal-interacting proteins. Localization of rNP22 is restricted to the cytoplasm and processes of neurons and it colocalizes with elements of the microfilament and microtubule matrices including filamentous actin (F-actin), alpha-tubulin, tau, and microtubule-associated protein 2 (MAP2). Withdrawal of Wistar rats after alcohol dependence induced by alcohol vapor produced elevated levels of rNP22 mRNA and protein in the cortex, CA2, and dentate gyrus regions of the hippocampus. In contrast, there was decreased rNP22 expression in the striatum after chronic ethanol exposure. Chronic ethanol exposure did not markedly alter rNP22 colocalization with F-actin, alpha-tubulin, or MAP2, although colocalization at the periphery of the neuronal soma with F-actin was observed only after chronic ethanol exposure and withdrawal. Rat NP22 colocalization with MAP2 was reduced during withdrawal, whereas association with alpha-tubulin and actin was maintained. These findings suggest that the effect of chronic ethanol exposure and withdrawal on rNP22 expression is region selective. Rat NP22 may affect microtubule or microfilament function, thereby regulating the neuroplastic changes associated with the development of alcohol dependence and physical withdrawal.

Actin Cytoskeleton↗

PubMed1997

Immunolocalization of nitric oxide synthases at the postsynaptic domain of human and rat neuromuscular junctions--light and electron microscopic studies.

Neuronal (n) and inducible (i) nitric oxide synthase (NOS) were immunolocalized at the postsynaptic domain of human and rat neuromuscular junctions (NMJs) by light and electron microscopy. We applied polyclonal and monoclonal antibodies for colocalization with three other synaptic proteins, utilizing double and triple fluorescence labeling, and gold and peroxidase for immunoelectron microscopy. By light microscopy, nNOS and iNOS colocalized with desmin and dystrophin, known postsynaptic components, but not with neurofilament protein, a presynaptic component. By electronmicroscopy, nNOS, but not iNOS, colocalized postsynaptically on the same structures as desmin; iNOS was also postsynaptic, but did not colocalize with desmin immunoreactivity. At the NMJs of Duchenne muscular dystrophy patients, both nNOS and iNOS were strongly immunoreactive. At the NMJs of a patient with myasthenia gravis, nNOS was weaker than in controls. Total denervation of rat sciatic nerve did not cause any decrease of nNOS or iNOS immunoreactivity 7 days thereafter. At 15 days after denervation, there was a gradual decrease of immunoreactivity, and immunoreactivity disappeared 30 days after denervation, corresponding to the ultrastructurally detectable disorganization of the postsynaptic region. This seems to be the first combined light and electron microscopic description of the postsynaptic localization of nNOS and iNOS at human and rat NMJs.

Adolescent↗