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Subunit Expression (subunit + expression)
Kinds of Subunit Expression Selected AbstractsThe effects of seizures on the connectivity and circuitry of the developing brainDEVELOPMENTAL DISABILITIES RESEARCH REVIEW, Issue 2 2004John W. Swann Abstract Recurring seizures in infants and children are often associated with cognitive deficits, but the reason for the learning difficulties is unclear. Recent studies in several animal models suggest that seizures themselves may contribute in important ways to these deficits. Other studies in animals have shown that recurring seizures result in dendritic spine loss. This change, coupled with a down-regulation in NMDA receptor subunit expression, suggests that repetitive seizures may interrupt the normal development of glutamatergic synaptic transmission. We hypothesize that homeostatic, neuroprotective processes are induced by recurring early-life seizures. These processes, by diminishing glutamatergic synaptic transmission, are aimed at preventing the continuation of seizures. However, by preventing the normal development of glutamatergic synapses, and particularly NMDA receptor-mediated synaptic transmission, such homeostatic processes also reduce synaptic plasticity and diminish the ability of neuronal circuits to learn and store memories. MRDD Research Reviews 2004;10:96,100. © 2004 Wiley-Liss, Inc. [source] Activity of nAChRs containing ,9 subunits modulates synapse stabilization via bidirectional signaling programsDEVELOPMENTAL NEUROBIOLOGY, Issue 14 2009Vidya Murthy Abstract Although the synaptogenic program for cholinergic synapses of the neuromuscular junction is well known, little is known of the identity or dynamic expression patterns of proteins involved in non-neuromuscular nicotinic synapse development. We have previously demonstrated abnormal presynaptic terminal morphology following loss of nicotinic acetylcholine receptor (nAChR) ,9 subunit expression in adult cochleae. However, the molecular mechanisms underlying these changes have remained obscure. To better understand synapse formation and the role of cholinergic activity in the synaptogenesis of the inner ear, we exploit the nAChR ,9 subunit null mouse. In this mouse, functional acetylcholine (ACh) neurotransmission to the hair cells is completely silenced. Results demonstrate a premature, effusive innervation to the synaptic pole of the outer hair cells in ,9 null mice coinciding with delayed expression of cell adhesion proteins during the period of effusive contact. Collapse of the ectopic innervation coincides with an age-related hyperexpression pattern in the null mice. In addition, we document changes in expression of presynaptic vesicle recycling/trafficking machinery in the ,9 null mice that suggests a bidirectional information flow between the target of the neural innervation (the hair cells) and the presynaptic terminal that is modified by hair cell nAChR activity. Loss of nAChR activity may alter transcriptional activity, as CREB binding protein expression is decreased coincident with the increased expression of N-Cadherin in the adult ,9 null mice. Finally, by using mice expressing the nondesensitizing ,9 L9,T point mutant nAChR subunit, we show that increased nAChR activity drives synaptic hyperinnervation. © 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2009 [source] Critical and sensitive periods for reversing the effects of mechanosensory deprivation on behavior, nervous system, and development in Caenorhabditis elegansDEVELOPMENTAL NEUROBIOLOGY, Issue 11 2007Susan Rai Abstract In these studies the nematode Caenorhabditis elegans was used as a model to investigate ways to reverse the effects of mechanosensory deprivation on behavior and development. Rose et al. (J Neurosci 2005; 25:7159,7168) showed that worms reared in isolation responded significantly less to a mechanical tap stimulus, were significantly smaller, and expressed significantly lower levels of a postsynaptic glutamate receptor subunit on the command interneurons of the tap response circuit and a presynaptic vesicle marker in the tap sensory neurons compared with worms raised in groups. Here, brief mechanical stimulation at any time throughout development reversed the effects of isolation on the response to tap and on postsynaptic glutamate receptor expression on the command interneurons, suggesting there is no critical period for these measures. In contrast to the high level of plasticity in glutamate receptor subunit expression on the interneurons, low levels of stimulation only rescued vesicle expression in the tap sensory neurons early in development and progressively higher levels of stimulation were required as the worm developed, suggesting a sensitive period immediately after hatching, followed by a period of decreasing plasticity. Stimulation during the first three stages of larval development, but not later, rescued the effects of isolation on worm length, suggesting there is a critical period for this measure that ends in the third larval stage. These results indicate that different effects of early isolation required different amounts and/or timing of stimulation to be reversed. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007. [source] Sex differences in anxiety, sensorimotor gating and expression of the ,4 subunit of the GABAA receptor in the amygdala after progesterone withdrawalEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2003M. Gulinello Abstract In a progesterone withdrawal (PWD) model of premenstrual anxiety, we have previously demonstrated that increased hippocampal expression of the ,4 subunit of the GABAA receptor (GABAA -R) is closely associated with higher anxiety levels in the elevated plus maze. However, several studies indicate that sex differences in regulation of the GABAA -R in specific brain regions may be an important factor in the observed gender differences in mood disorders. Thus, we investigated possible sex differences in GABAA -R subunit expression and anxiety during PWD. To this end, we utilized the acoustic startle response (ASR) to assess anxiety levels in male and female rats undergoing PWD as the ASR is also applicable to the assessment of human anxiety responses. We also investigated GABAA -R ,4 subunit expression in the amygdala, as the amygdala directly regulates the primary startle circuit. Female rats exhibited a greater ASR during PWD than controls, indicating higher levels of anxiety and arousal. In contrast, male rats undergoing PWD did not demonstrate an increased ASR. The sex differences in the ASR were paralleled by sex differences in the expression of the GABAA -R ,4 subunit in the amygdala such that ,4 subunit expression was up-regulated in females during PWD whereas ,4 levels in males undergoing PWD were not altered relative to controls. These findings might have implications regarding gender differences in human mood disorders and the aetiology of premenstrual anxiety. [source] Autocrine motility factor enhances hepatoma cell invasion across the basement membrane through activation of ,1 integrinsHEPATOLOGY, Issue 1 2001Takuji Torimura Autocrine motility factor/phosphohexose isomerase (AMF/PHI) is a cytokine that is linked to tumor invasion and metastasis. In hepatocellular carcinoma (HCC) tissues, hepatoma cells produce AMF/PHI and its receptor, Mr 78,000 glycoprotein (gp78), is strongly detected in hepatoma cells invading into the stroma and tumor thrombi in the portal vein. Here, we investigated the mechanism of hepatoma cell invasion through Matrigel induced by AMF/PHI using 3 hepatoma cell lines. Production of AMF/PHI, phosphorylation of MEK1/2, and Rho activity were investigated by immunoblotting. Expression of AMF/PHI and gp78 was observed by confocal fluorescence microscopy. The influence of AMF/PHI on activated integrin ,1 subunit expression was evaluated by flow cytometry. Changes in invasion, adhesion, and motility induced by AMF/PHI were evaluated using chemoinvasion, adhesion, and phagokinetic track motility assays. The effect of AMF/PHI on matrix metalloproteinase (MMP) secretion was evaluated by gelatin zymography. Hepatoma cells produced AMF/PHI and expressed gp78. Although AMF/PHI was ubiquitously detected, gp78 was strongly expressed in migrating cells. AMF/PHI induced up-regulation of activated integrin ,1 subunit expression. AMF/PHI stimulated hepatoma cell invasion through Matrigel, and stimulated the adhesion, motility, and MMP-2 secretion of hepatoma cells. The latter effects were suppressed by the function-blocking antibody for integrin ,1 subunit. AMF/PHI also enhanced Rho activity and the phosphorylation of MEK1 and MEK 2. Our results indicate that AMF/PHI enhances hepatoma cell invasion through Matrigel in an autocrine manner by stimulating the adhesion, motility, and MMP-2 secretion of these cells through activation of ,1 integrins. [source] Developmental expression of potassium-channel subunit Kv3.2 within subpopulations of mouse hippocampal inhibitory interneurons,HIPPOCAMPUS, Issue 2 2002Emily Phillips Tansey Abstract The developmental expression of the voltage-gated potassium channel subunit, Kv3.2, and its localization within specific mouse hippocampal inhibitory interneuron populations were determined using immunoblotting and immunohistochemical techniques. Using immunoblotting techniques, the Kv3.2 protein was weakly detected at postnatal age day 7 (P7), and full expression was attained at P21 in tissue extracts from homogenized hippocampal preparations. A similar developmental profile was observed using immunohistochemical techniques in hippocampal tissue sections. Kv3.2 protein expression was clustered on the somata and proximal dendrites of presumed inhibitory interneurons. Using double immunofluorescence, Kv3.2 subunit expression was detected on subpopulations of GABAergic inhibitory interneurons. Kv3.2 was detected in ,100% of parvalbumin-positive interneurons, 86% of interneurons expressing nitric oxide synthase, and ,50% of somatostatin-immunoreactive cells. Kv3.2 expression was absent from both calbindin- and calretinin-containing interneurons. Using immunoprecipitation, we further demonstrate that Kv3.2 and its related subunit Kv3.1b are coexpressed within the same protein complexes in the hippocampus. These data demonstrate that potassium channel subunit Kv3.2 expression is developmentally regulated in a specific set of interneurons. The vast majority of these interneuron subpopulations possess a "fast-spiking" phenotype, consistent with a role for currents through Kv3.2 containing channels in determining action potential kinetics in these cells. Hippocampus 2002;12:137,148. Published 2002 Wiley-Liss, Inc. [source] The microanatomy of the distal arrector pili: possible role for ,1,1 and ,5,1 integrins in mediating cell-cell adhesion and anchorage to the extracellular matrixJOURNAL OF CUTANEOUS PATHOLOGY, Issue 2 2000Jeri Kersten Mendelson The arrector pili (AP) muscle is a small band of smooth muscle that attaches proximally to the bulge area of the pilosebaceous apparatus in the reticular dermis and extends up toward the epidermis. The distal anatomy of the AP and the anchorage mechanism allowing hair erection have not been previously described. Integrins are likely candidates mediating this attachment. Immunohistochemical techniques were used to determine the distribution of the following integrins: ,1, ,2, ,3, ,4, ,5, ,6 and ,1 as well as fibronectin. Frozen human scalp tissue was sectioned in traditional planes, obliquely and horizontally to visualize microanatomy in three dimensions. Histological examination revealed that the distal portions of smooth muscle fibers splay extensively between collagen bundles of the upper dermis. Integrin subunits ,1, ,5 and ,1 were expressed by the AP muscle. Analysis of the relative density of immunoreactivity in digitized sections revealed increased ,5 subunit expression at the extracellular matrix (ECM)-muscle interface. These data suggest that anchorage of the AP muscle to the ECM is via ,5,1 integrin and ,1,1 integrin functions in muscle cell-cell adhesion. Extensive splaying of smooth muscle fibers may allow increased surface area contact between the ECM and smooth muscle cells expressing peripherally situated ,5 integrin. [source] Aging-dependent upregulation of IL-23p19 gene expression in dendritic cells is associated with differential transcription factor binding and histone modificationsAGING CELL, Issue 5 2009Rabab El Mezayen Summary Age-associated changes in immune response increase the risk of infection and promote inflammation and autoimmunity in older adults. The newly discovered cytokine IL-23 contributes to the maintenance and expansion of Th-17 cells, which promote proinflammatory responses. Our preliminary findings suggested that Th-17 responses are increased in aged mice. IL-23 consists of p40 and p19 subunits. Expression of the p19 subunit is regulated at the transcriptional level by NF-,B p65 and c-Rel transcription factors. Using bone-marrow-derived dendritic cells (DCs) from C57BL/6 mice, we show that IL-23 protein production and p19 subunit mRNA levels are significantly increased in DCs from aged mice after activation with TLR ligands (LPS + R848) when compared with DCs of young adult mice. We found that the increase in p19 expression in aged cells is associated with chromatin remodeling characterized by di- and tri-methylation of histone H3K4 and binding of mainly c-Rel at the p19 promoter. In young DCs, the promoter is tri-methylated only at H3K4 and bound by both p65 and c-Rel. C-Rel knockdown restores p65 binding in aged cells but does not activate p19 expression, suggesting that c-Rel is critical for p19 expression. In addition, p65 knockdown significantly increases c-Rel binding and p19 expression in young DCs to levels close to those detected in old cells. Furthermore, the decrease in p65 binding at the p19 promoter in old DCs was specific to the p19 gene since p65 binding to the IL-12p40 promoter was not significantly different between old and young DCs. Our results demonstrate that selective changes in H3K4 methylation, and c-Rel and p65 binding at the p19 promoter occur in DCs and contribute to the upregulation of the p19 subunit expression and IL-23 protein production observed in aged mice. This suggests epigenetic and transcriptional mechanisms contribute to dysregulated inflammatory and autoimmune responses associated with aging. [source] Molecular determinants of ginkgolide binding in the glycine receptor poreJOURNAL OF NEUROCHEMISTRY, Issue 2 2006Rebecca Hawthorne Abstract Ginkgolides are potent blockers of the glycine receptor Cl, channel (GlyR) pore. We sought to identify their binding sites by comparing the effects of ginkgolides A, B and C and bilobalide on ,1, ,2, ,1, and ,2, GlyRs. Bilobalide sensitivity was drastically reduced by incorporation of the , subunit. In contrast, the sensitivities to ginkgolides B and C were enhanced by , subunit expression. However, ginkgolide A sensitivity was increased in the ,2, GlyR relative to the ,2 GlyR but not in the ,1, GlyR relative to the ,1 GlyR. We hypothesised that the subunit-specific differences were mediated by residue differences at the second transmembrane domain 2, and 6, pore-lining positions. The increased ginkgolide A sensitivity of the ,2, GlyR was transferred to the ,1, GlyR by the G2,A (,1 to ,2 subunit) substitution. In addition, the ,1 subunit T6,F mutation abolished inhibition by all ginkgolides. As the ginkgolides share closely related structures, their molecular interactions with pore-lining residues were amenable to mutant cycle analysis. This identified an interaction between the variable R2 position of the ginkgolides and the 2, residues of both ,1 and , subunits. These findings provide strong evidence for ginkgolides binding at the 2, pore-lining position. [source] Dysfunction of the ubiquitin,proteasome system in Parkinson's diseaseJOURNAL OF NEUROCHEMISTRY, Issue 2003P. Jenner The cause of nigral cell degeneration and Lewy body formation in Parkinson's disease (PD) remains unknown but may involve impaired proteolysis. Evidence from both sporadic and familial forms of PD suggest the involvement of alterations in the ubiquitin,proteasomal system. In postmortem tissues from PD cases, there is a loss of 26S proteasomal enzyme activity coupled to a decrease in the expression of ,-subunits in substantia nigra while ,-subunit expression remains unchanged. The expression of PA700 is up-regulated in a number of brain regions in PD but not in substantia nigra. Interestingly, there was little or no expression of PA28 in the nigra in both aged control tissue or in PD. These data suggest that alterations in protein handling may be key to the formation of Lewy bodies in PD. Indeed, in vitro and in vivo inhibition of proteasomal activity causes the death of dopaminergic neurones. Recent evidence suggests that the formation of Lewy bodies may be linked to impaired proteasomal function in centrosomes leading to aggresome formation. [source] P2X2, P2X2,2 and P2X5 receptor subunit expression and function in rat thoracolumbar sympathetic neuronsJOURNAL OF NEUROCHEMISTRY, Issue 5 2001H. Schädlich The present study investigated the pharmacological properties of excitatory P2X receptors and P2X2 and P2X5 receptor subunit expression in rat-cultured thoracolumbar sympathetic neurons. In patch-clamp recordings, ATP (3,1000 µm; applied for 1 s) induced inward currents in a concentration-dependent manner. Pyridoxal-phosphate-6-azophenyl-2,,4,-disulfonate (PPADS; 30 µm) counteracted the ATP response. In contrast to ATP, ,,,-meATP (30 µm; for 1 s) was virtually ineffective. Prolonged application of ATP (100 µm; 10 s) induced receptor desensitization in a significant proportion of sympathetic neurons in a manner typical for P2X2,2 splice variant-mediated responses. Using single-cell RT-PCR, P2X2, P2X2,2 and P2X5 mRNA expression was detectable in individual tyrosine hydroxylase-positive neurons; coexpression of both P2X2 isoforms was not observed. Laser scanning microscopy revealed both P2X2 and P2X5 immunoreactivity in virtually every TH-positive neuron. P2X2 immunoreactivity was largely distributed over the cell body, whereas P2X5 immunoreactivity was most distinctly located close to the nucleus. In summary, the present study demonstrates the expression of P2X2, P2X2,2 and P2X5 receptor subunits in rat thoracolumbar neurons. The functional data in conjunction with a preferential membranous localization of P2X2/P2X2,2 compared with P2X5 suggest that the excitatory P2X responses are mediated by P2X2 and P2X2,2 receptors. Apparently there exist two types of P2X2 receptor-bearing sympathetic neurons: one major population expressing the unspliced isoform and another minor population expressing the P2X2,2 splice variant. [source] Social Stress Alters Expression of Large Conductance Calcium-Activated Potassium Channel Subunits in Mouse Adrenal Medulla and Pituitary GlandsJOURNAL OF NEUROENDOCRINOLOGY, Issue 3 2009O. Chatterjee Large conductance calcium-activated potassium (BK) channels are very prominently expressed in adrenal chromaffin and many anterior pituitary cells, where they shape intrinsic excitability complexly. Stress- and sex-steroids regulate alternative splicing of Slo-,, the pore-forming subunit of BK channels, and chronic behavioural stress has been shown to alter Slo splicing in tree shrew adrenals. In the present study, we focus on mice, measuring the effects of chronic behavioural stress on total mRNA expression of the Slo-, gene, two key BK channel , subunit genes (,2 and ,4), and the ,STREX' splice variant of Slo-,. As a chronic stressor, males of the relatively aggressive SJL strain were housed with a different unfamiliar SJL male every 24 h for 19 days. This ,social-instability' paradigm stressed all individuals, as demonstrated by reduced weight gain and elevated corticosterone levels. Five quantitative reverse transcriptase-polymerase chain assays were performed in parallel, including ,-actin, each calibrated against a dilution series of its corresponding cDNA template. Stress-related changes in BK expression were larger in mice tested at 6 weeks than 9 weeks. In younger animals, Slo-, mRNA levels were elevated 44% and 116% in the adrenal medulla and pituitary, respectively, compared to individually-housed controls. ,2 and ,4 mRNAs were elevated 162% and 194% in the pituitary, but slightly reduced in the adrenals of stressed animals. In the pituitary, dominance scores of stressed animals correlated negatively with , and , subunit expression, with more subordinate individuals exhibiting levels that were three- to four-fold higher than controls or dominant individuals. STREX variant representation was lower in the subordinate subset. Thus, the combination of subunits responding to stress differs markedly between adrenal and pituitary glands. These data suggest that early stress will differentially affect neuroendocrine cell excitability, and call for detailed analysis of functional consequences. [source] Effect of Chronic Stress and Mifepristone Treatment on Voltage-Dependent Ca2+ Currents in Rat Hippocampal Dentate GyrusJOURNAL OF NEUROENDOCRINOLOGY, Issue 10 2006N. G. Van Gemert Chronic unpredictable stress affects many properties in rat brain. In the dentate gyrus, among other things, increased mRNA expression of the Ca2+ channel ,1C subunit has been found after 21 days of unpredictable stress in combination with acute corticosterone application (100 nM). In the present study, we examined: (i) whether these changes in expression are accompanied by altered Ca2+ currents in rat dentate granule cells recorded on day 22 and (ii) whether treatment with the glucocorticoid receptor antagonist mifepristone during the last 4 days of the stress protocol normalises the putative stress-induced effects. Three weeks of unpredictable stress did not affect Ca2+ current amplitude in dentate granule cells under basal conditions (i.e. after incubation with vehicle solution). However, the sustained Ca2+ current component (which largely depends on the ,1C subunit) was significantly increased in amplitude after chronic stress when slices had been treated with corticosterone 1,4 h before recording. These findings suggest that dentate granule cells are exposed to an increased calcium load after exposure to an acute stressor when they have a history of chronic stress, potentially leading to increased vulnerability of the cells. The present results are in line with the molecular data on Ca2+ channel ,1C subunit expression. A significant three-way interaction between chronic stress, corticosterone application and mifepristone treatment was found, indicating that the combined effect of stress and corticosterone depends on mifepristone cotreatment. Interestingly, current density (defined as total current divided by capacitance) did not differ between the groups. This indicates that the observed changes in Ca2+ current amplitude could be attributable to changes in cell size. [source] Chronic Ethanol-Induced Subtype- and Subregion-Specific Decrease in the mRNA Expression of Metabotropic Glutamate Receptors in Rat HippocampusALCOHOLISM, Issue 9 2004Agnes Simonyi Background: Chronic ethanol consumption is known to induce adaptive changes in the hippocampal glutamatergic transmission and alter NMDA receptor binding and subunit expression. Metabotropic glutamate (mGlu) receptors have been shown to function as modulators of neuronal excitability and can fine tune glutamatergic transmission. This study was aimed to determine whether chronic ethanol treatment could change the messenger RNA (mRNA) expression of mGlu receptors in the hippocampus. Methods: Male Sprague Dawley® rats were fed a Lieber-DeCarli liquid diet with 5% (w/v) ethanol or isocaloric amount of maltose for 2 months. Quantitative in situ hybridization was carried out using coronal brain sections through the hippocampus. Results: The results revealed decreases in mRNA expression of several mGlu receptors in different subregions of the hippocampus. In the dentate gyrus, mGlu3 and mGlu5 receptor mRNA levels were significantly lower in the ethanol-treated rats than in the control rats. In the CA3 region, the mRNA expression of mGlu1, mGlu5, and mGlu7 receptors showed substantial decreases after ethanol exposure. The mGlu7 receptor mRNA levels were also declined in the CA1 region and the polymorph layer of the dentate gyrus. No changes were found in mRNA expression of mGlu2, mGlu4, and mGlu8 receptors. Conclusions: Considering the involvement of hippocampal mGlu receptors in learning and memory processes as well as in neurotoxicity and seizure production, the reduced expression of these receptors might contribute to ethanol withdrawal-induced seizures and also may play a role in cognitive deficits and brain damage caused by long-term ethanol consumption. [source] KATP -mediated Vasodilation is Impaired in Obese Zucker RatsMICROCIRCULATION, Issue 6 2008BENJAMIN L. HODNETT ABSTRACT Objective: Skeletal muscle blood flow during exercise is impaired in obesity. We tested the hypothesis that the attenuated vasodilation in skeletal muscle arterioles of obese Zucker rats (OZR) is due to altered KATP channel-mediated vasodilation. Materials and Methods: KATP channel function was determined in isolated skeletal muscle arterioles in response to the KATP opener cromakalim (0.1,10 , M) during normal myogenic tone and , -adrenergic-mediated tone (0.1 , M phenylephrine). The spinotrapezius muscle was prepared and the vasodilatory responses to muscle stimulation or iloprost (0.028,2.8 , M) were observed before and after the application of the KATP inhibitor, glibenclamide (10 , M). Channel subunit expression was determined by using western blot analyses. Results: Cromakalim concentration-response curves were shifted in OZR as compared to lean controls. OZR exhibited impaired functional and iloprost-induced vasodilation as compared to the lean controls. Glibenclamide inhibited the functional and iloprost-induced dilation in the lean rats with no effects in the obese animals. Channel subunit expression was similar in femoral arteries. Conclusion:The impaired functional vasodilation in the OZR is associated with altered KATP channel sensitivity. [source] Acetylcholine receptor-, subunit expression in myasthenia gravis: A role for the autoantigen in pathogenesis?MUSCLE AND NERVE, Issue 2 2009Jian Rong Sheng PhD Abstract Previous studies have shown increased expression of acetylcholine receptor-alpha (AChR-,) subunit transcripts in myasthenia gravis (MG) and experimental MG (EAMG), but none examined the functional properties of this overexpression. In this study we examined the mRNA and protein expression of AChR-, as well as the pattern of ,-bungarotoxin labeling in muscle tissue from EAMG mice with varying disease severity. AChR-, expression was increased considerably in endplates from mice with severe EAMG, but it was distinct and greatly in excess of ,-bungarotoxin labeling. This "aberrant expression" occurred in mice with morphologic endplate damage, and the pattern of complement and immunoglobulin deposition in muscle from these mice appeared to mirror the pattern of AChR-, expression. The loss of functional AChR in severe MG increases transcription of AChR-, mRNA, but the expressed protein is "functionally inert," failing to compensate for loss of AChR. This enhanced expression of AChR may play a role in driving the ongoing autoimmune response. Muscle Nerve 40: 279,286, 2009 [source] Protein distribution of Kcnq1, Kcnh2, and Kcne3 potassium channel subunits during mouse embryonic developmentTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 3 2006Marķa Pilar de Castro Abstract Voltage-dependent potassium channels consist of a pore-forming ,-subunit, which is modulated by additional ,-ancillary or regulatory subunits. Kcnq1 and Kcnh2 ,-channel subunits play pivotal roles in the developing and adult heart. However, Kcnq1 and Kcnh2 have a much wider expression profile than strictly confined to the myocardium, similar to their putative regulatory Kcne1-5 ,-subunits. At present, the distribution of distinct potassium channel subunits has been partially mapped in adult tissues, whereas almost no information is available during embryonic development. In this study, we report a detailed analysis of Kcnq1, Kcnh2, and Kcne3 protein expression during mouse embryogenesis. Our results demonstrate that Kcnq1 and Kcnh2 are widely distributed. Coexpression of both ,-subunits is observed in a wide variety of organs, such as heart and the skeletal muscle, whereas others display unique Kcnq1 or Knch2 expression. Interestingly, Kcne3 expression is also widely observed in distinct tissue layers during embryogenesis, supporting the notion that an exquisite balance of ,- and ,-subunit expression is required for modulating potassium conductance in distinct organs and tissue layers. © 2006 Wiley-Liss, Inc. [source] Developmental regulation of neuron-specific P2X3 receptor expression in the rat cochleaTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 2 2005Lin-Chien Huang Abstract ATP-gated ion channels assembled from P2X3 receptor (P2X3R) subunits contribute to neurotransmission and neurotrophic signaling, associated with neurite development and synaptogenesis, particularly in peripheral sensory neurons. Here, P2X3R expression was characterized in the rat cochlea from embryonic day 16 (E16) to adult (P49,56), using RT-PCR and immunohistochemistry. P2X3R mRNA was strongly expressed in the cochlea prior to birth, declined to a minimal level at P14, and was absent in adult tissue. P2X3R protein expression was confined to spiral ganglion neurons (SGN) within Rosenthal's canal of the cochlea. At E16, immunolabeling was detected in the SGN neurites, but not the distal neurite projection within the developing sensory epithelium (greater epithelial ridge). From E18, the immunolabeling was observed in the peripheral neurites innervating the inner hair cells but was reduced by P6. However, from P2,8, immunolabeling of the SGN neurites extended to include the outer spiral bundle fiber tract beneath the outer hair cells. This labeling of type II SGN afferent fiber declined after P8. By P14, all synaptic terminal immunolabeling in the organ of Corti was absent, and SGN cell body labeling was minimal. In adult cochlear tissue, P2X3R immunolabeling was not detected. Noise exposure did not induce P2X3R expression in the adult cochlea. These data indicate that ATP-gated ion channels incorporating P2X3R subunit expression are specifically targeted to the afferent terminals just prior to the onset of hearing, and likely contribute to the neurotrophic signaling which establishes functional auditory neurotransmission. J. Comp. Neurol. 484:133,143, 2005. © 2005 Wiley-Liss, Inc. [source] Co-regulation of ocular dominance plasticity and NMDA receptor subunit expression in glutamic acid decarboxylase-65 knock-out miceTHE JOURNAL OF PHYSIOLOGY, Issue 12 2009Patrick O. Kanold Experience can shape cortical circuits, especially during critical periods for plasticity. In visual cortex, imbalance of activity from the two eyes during the critical period shifts ocular dominance (OD) towards the more active eye. Inhibitory circuits are crucial in this process: OD plasticity is absent in GAD65KO mice that show diminished inhibition. This defect can be rescued by application of benzodiazepines, which increase GABAergic signalling. However, it is unknown how such changes in inhibition might disrupt and then restore OD plasticity. Since NMDA dependent synaptic plasticity mechanisms are also known to contribute to OD plasticity, we investigated whether NMDA receptor levels and function are also altered in GAD65KO. There are reduced NR2A levels and slower NMDA currents in visual cortex of GAD65KO mice. Application of benzodiazepines, which rescues OD plasticity, also increases NR2A levels. Thus it appears as if OD plasticity can be restored by adding a critical amount of excitatory transmission through NR2A-containing NMDA receptors. Together, these observations can unify competing ideas of how OD plasticity is regulated: changes in either inhibition or excitation would engage homeostatic mechanisms that converge to regulate NMDA receptors, thereby enabling plasticity mechanisms and also ensuring circuit stability. [source] Neuropathology and Pathogenesis of Encephalitis following Amyloid , Immunization in Alzheimer's DiseaseBRAIN PATHOLOGY, Issue 1 2004Isidre Ferrer Immunizing transgenic PDAPP mice, which overexpress mutant APP and develop ,-amyloid deposition resembling plaques in Alzheimer's disease (AD), results in a decrease of amyloid burden when compared with non treated transgenic animals im-munization with amyloid , peptide has been initiated in a randomised pilot study in AD. Yet a minority of patients developed a neurological complication consistent with meningoencephalitis and one patient died; the trial has been stopped. Neuropathological examination in that patient showed meningoencephalitis and focal atypically low numbers of diffuse and neuritic plaques but not of vascular amyloid nor regression of tau pathology in neurofibrillary tangles and neuropil threads. The present neuropathological study reports the second case of menigoencephalitis following immunization with amyloid-, peptide in AD, and has been directed toward exploring mechanisms underlying decreased tau pathology in relation- with amyliod deposit regression, and possible molecular bases involved in the inflammatory response following immunization. Inflammatory infiltrates were composed of CD8+, CD3+, CD5+ and, rarely, CD7+ lymphocytes, whereas B lymphocytes and T cytotoxic cells CD16, CD57, TIA and graenzyme were negative. Characteristic neuropathological findings were focal depletion of diffuse and neuritic plaques, but not of amyloid angiopathy, and the presence of small numbers of extremely dense(collapsed) plaques surrounded by active microglia, and multinucleated giant cells filled with dense A,42and A,40, in addition to severe small cerebral blood Reduced amyloid burden was accompanied by low amyloid-associated oxidative stress responses (reduced superoxide dismutase-1:SOD-1 expression) and by local inhibition of the stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) and p38 kinase which are involved in tau phosphorylation. These results support the amyloid cascade of tau phosphorylation in AD regarding phosphorylation of tau in neurofibrillary tangles and ,-amyloid deposition in neuritic plaques, but not of tau in neurofibrillary tangles and threads. Furthermore, amyloid reduction was accompanied by increased expression of the PA28,/, inductor, and of LMP7, LMP2 and MECL1 subunits of the immunopro-teasome in microglial and inflammatory cells surrounding collapsed plaques, and in multinucleated giant cells.Immunoproteasome subunit expression was accompanied by local presentation of MHC class molecules. Release of antigenic peptides derived from ,-amyloid processing may enhance T-cell inflammatory responses accounting for the meningoencephalitis following amyloid-, peptide immunization [source] New blood for hemoglobin in the lens: roles in stem cell differentiation and fibre cell organelle loss?ACTA OPHTHALMOLOGICA, Issue 2008MA WRIDE Purpose Evidence is emerging for haemoglobin (Hb) expression outside the vascular system. We previously demonstrated Hb expression in the mouse lens during post-natal development and cataract progression. Here, we extended this work by carrying out a comprehensive spatio-temporal analysis of Hb subunit expression during mouse lens development and maturation. Methods We used RT-PCR, Western blotting and immunofluorescence to analyze Hb expression in mouse eyes (E16.5 to 9 wks). We also used a sensitive heme assay to test for the presence of heme in the lens by colourimetric assay and histological staining of paraffin-embedded sections. Results Hb subunits were expressed in lens epithelial cells and cortical lens fibre cells. However, the heme assay revealed negligible levels of this prosthetic group in the lens. Hb immunofluorescence was also observed in other regions of the developing eye including the cornea, the retinal ganglion cell layer and the retinal pigment epithelium. Finally, we also observed Hb expression in early embryos by microarray and during differentiation of embryonic stem (ES) cells into embryoid bodies (EBs) in vitro. Conclusion These results suggest a paradigm shift: Hb subunits are expressed in the eye during development and in the adult and, therefore, may have novel roles in ocular development, physiology and pathophysiology. The absence of heme from the lens indicates that at least some of these functions may be independent of oxygen metabolism. The pattern of expression of Hb in lens epithelial cells and cortical lens fibre cells may indicate an involvement for Hb subunits in lens epithelial cell differentiation into lens fibre cells and/or lens fibre cell organelle loss. [source] | |||||||||||||||||||||||||