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  • α-Synuclein-induced synapse damage in cultured neurons is mediated by cholesterol-sensitive activation of cytoplasmic phospholipase A2. 25761116

    The accumulation of aggregated forms of the α-synuclein (αSN) is associated with the pathogenesis of Parkinson's disease (PD) and Dementia with Lewy Bodies. The loss of synapses is an important event in the pathogenesis of these diseases. Here we show that aggregated recombinant human αSN, but not βSN, triggered synapse damage in cultured neurons as measured by the loss of synaptic proteins. Pre-treatment with the selective cytoplasmic phospholipase A2 (cPLA2) inhibitors AACOCF3 and MAFP protected neurons against αSN-induced synapse damage. Synapse damage was associated with the αSN-induced activation of synaptic cPLA2 and the production of prostaglandin E2. The activation of cPLA2 is the first step in the generation of platelet-activating factor (PAF) and PAF receptor antagonists (ginkgolide B or Hexa-PAF) also protect neurons against αSN-induced synapse damage. αSN-induced synapse damage was also reduced in neurons pre-treated with the cholesterol synthesis inhibitor (squalestatin). These results are consistent with the hypothesis that αSN triggered synapse damage via hyperactivation of cPLA2. They also indicate that αSN-induced activation of cPLA2 is influenced by the cholesterol content of membranes. Inhibitors of this pathway that can cross the blood brain barrier may protect against the synapse damage seen during PD.
    Document Type:
    Reference
    Product Catalog Number:
    MAB368

  • α-synuclein induced synapse damage is enhanced by amyloid-β1-42. 21138585

    The pathogenesis of Parkinson's disease (PD) and dementia with Lewy bodies (DLB) is associated with the accumulation of aggregated forms of the α-synuclein (αSN) protein. An early event in the neuropathology of PD and DLB is the loss of synapses and a corresponding reduction in the level of synaptic proteins. However, the molecular mechanisms involved in synapse damage in these diseases are poorly understood. In this study the process of synapse damage was investigated by measuring the amount of synaptophysin, a pre-synaptic membrane protein essential for neurotransmission, in cultured neurons incubated with αSN, or with amyloid-β (Aβ) peptides that are thought to trigger synapse degeneration in Alzheimer's disease.We report that the addition of recombinant human αSN reduced the amount of synaptophysin in cultured cortical and hippocampal neurons indicative of synapse damage. αSN also reduced synaptic vesicle recycling, as measured by the uptake of the fluorescent dye FM1-43. These effects of αSN on synapses were modified by interactions with other proteins. Thus, the addition of βSN reduced the effects of αSN on synapses. In contrast, the addition of amyloid-β (Aβ)1-42 exacerbated the effects of αSN on synaptic vesicle recycling and synapse damage. Similarly, the addition of αSN increased synapse damage induced by Aβ1-42. However, this effect of αSN was selective as it did not affect synapse damage induced by the prion-derived peptide PrP82-146.These results are consistent with the hypothesis that oligomers of αSN trigger synapse damage in the brains of Parkinson's disease patients. Moreover, they suggest that the effect of αSN on synapses may be influenced by interactions with other peptides produced within the brain.
    Document Type:
    Reference
    Product Catalog Number:
    MAB368

  • α(2A)-adrenergic receptors filter parabrachial inputs to the bed nucleus of the stria terminalis. 25009265

    α2-adrenergic receptors (AR) within the bed nucleus of the stria terminalis (BNST) reduce stress-reward interactions in rodent models. In addition to their roles as autoreceptors, BNST α(2A)-ARs suppress glutamatergic transmission. One prominent glutamatergic input to the BNST originates from the parabrachial nucleus (PBN) and consists of asymmetric axosomatic synapses containing calcitonin gene-related peptide (CGRP) and vGluT2. Here we provide immunoelectron microscopic data showing that many asymmetric axosomatic synapses in the BNST contain α(2A)-ARs. Further, we examined optically evoked glutamate release ex vivo in BNST from mice with virally delivered channelrhodopsin2 (ChR2) expression in PBN. In BNST from these animals, ChR2 partially colocalized with CGRP, and activation generated EPSCs in dorsal anterolateral BNST neurons that elicited two cell-type-specific outcomes: (1) feedforward inhibition or (2) an EPSP that elicited firing. We found that the α(2A)-AR agonist guanfacine selectively inhibited this PBN input to the BNST, preferentially reducing the excitatory response in ex vivo mouse brain slices. To begin to assess the overall impact of α(2A)-AR control of this PBN input on BNST excitatory transmission, we used a Thy1-COP4 mouse line with little postsynaptic ChR2 expression nor colocalization of ChR2 with CGRP in the BNST. In slices from these mice, we found that guanfacine enhanced, rather than suppressed, optogenetically initiated excitatory drive in BNST. Thus, our study reveals distinct actions of PBN afferents within the BNST and suggests that α(2A)-AR agonists may filter excitatory transmission in the BNST by inhibiting a component of the PBN input while enhancing the actions of other inputs.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple

  • α(V)β(3) integrin-targeted PLGA-PEG nanoparticles for enhanced anti-tumor efficacy of a Pt(IV) prodrug. 22584163

    Targeted delivery of therapeutics to tumor neovasculature is potentially a powerful approach for selective cancer treatment. Integrins are heterodimeric transmembrane proteins involved in cell adhesion and cell signaling, and their expression is commonly upregulated in cancers and inflammatory diseases. The α(v)β(3) integrin is differentially upregulated on angiogenic endothelial cells as well as on many cancer cells. Here we demonstrate the differential targeting of cisplatin prodrug-encapsulated poly(d,l-lactic-co-glycolic acid)-block-polyethylene glycol (PLGA-PEG) nanoparticles (NPs) to the α(v)β(3) integrin on cancer cells using the cyclic pentapeptide c(RGDfK). Cisplatin is one of the most widely used anticancer drugs, and approaches that can improve its therapeutic index are of broad importance. The RGD-targeted Pt(IV)-encapsulated NPs displayed enhanced cytotoxicity as compared to cisplatin administered in its conventional dosage form in model prostate and breast cancer epithelial cells in vitro. Cytotoxicities were also elevated in comparison to those of previously reported systems, a small molecule Pt(IV)-RGD conjugate and a Pt(IV) nanoscale coordination polymer carrying RGD moieties. This result encouraged us also to evaluate the anticancer effect of the new construct in an animal model. The RGD-targeted PLGA-PEG NPs were more efficacious and better tolerated by comparison to cisplatin in an orthotopic human breast cancer xenograft model in vivo.
    Document Type:
    Reference
    Product Catalog Number:
    MAB1976F
    Product Catalog Name:
    Anti-Integrin αVβ3 Antibody, clone LM609, FITC conjugated

  • α6* nicotinic acetylcholine receptor expression and function in a visual salience circuit. 22836257

    Nicotinic acetylcholine receptors (nAChRs) containing α6 subunits are expressed in only a few brain areas, including midbrain dopamine (DA) neurons, noradrenergic neurons of the locus ceruleus, and retinal ganglion cells. To better understand the regional and subcellular expression pattern of α6-containing nAChRs, we created and studied transgenic mice expressing a variant α6 subunit with green fluorescent protein (GFP) fused in-frame in the M3-M4 intracellular loop. In α6-GFP transgenic mice, α6-dependent synaptosomal DA release and radioligand binding experiments confirmed correct expression and function in vivo. In addition to strong α6* nAChR expression in glutamatergic retinal axons, which terminate in superficial superior colliculus (sSC), we also found α6 subunit expression in a subset of GABAergic cell bodies in this brain area. In patch-clamp recordings from sSC neurons in brain slices from mice expressing hypersensitive α6* nAChRs, we confirmed functional, postsynaptic α6* nAChR expression. Further, sSC GABAergic neurons expressing α6* nAChRs exhibit a tonic conductance mediated by standing activation of hypersensitive α6* nAChRs by ACh. α6* nAChRs also appear in a subpopulation of SC neurons in output layers. Finally, selective activation of α6* nAChRs in vivo induced sSC neuronal activation as measured with c-Fos expression. Together, these results demonstrate that α6* nAChRs are uniquely situated to mediate cholinergic modulation of glutamate and GABA release in SC. The SC has emerged as a potential key brain area responsible for transmitting short-latency salience signals to thalamus and midbrain DA neurons, and these results suggest that α6* nAChRs may be important for nicotinic cholinergic sensitization of this pathway.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple

  • β-Catenin signaling is a critical event in ErbB2-mediated mammary tumor progression. 23720052

    Although ERBB2 amplification and overexpression is correlated with poor outcome in breast cancer, the molecular mechanisms underlying the aggressive nature of these tumors has not been fully elucidated. To investigate this further, we have used a transgenic mouse model of ErbB2-driven tumor progression (ErbB2(KI) model) that recapitulates clinically relevant events, including selective amplification of the core erbB2 amplicon. By comparing the transcriptional profiles of ErbB2(KI) mammary tumors and human ERBB2-positive breast cancers, we show that ErbB2(KI) tumors possess molecular features of the basal subtype of ERBB2-positive human breast cancer, including activation of canonical β-catenin signaling. Inhibition of β-catenin-dependent signaling in ErbB2(KI)-derived tumor cells using RNA interference impaired tumor initiation and metastasis. Furthermore, treatment of ErbB2(KI) or human ERBB2-overexpressing tumor cells with a selective β-catenin/CBP inhibitor significantly decreased proliferation and ErbB2 expression. Collectively, our data indicate that ERBB2-mediated breast cancer progression requires β-catenin signaling and can be therapeutically targeted by selective β-catenin/CBP inhibitors.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple

  • β3 integrin is dispensable for conditioned fear and Hebbian forms of plasticity in the hippocampus. 22748100

    Integrins play key roles in the developing and mature nervous system, from promoting neuronal process outgrowth to facilitating synaptic plasticity. Recently, in hippocampal pyramidal neurons, β3 integrin (ITGβ3) was shown to stabilise synaptic AMPA receptors (AMPARs) and to be required for homeostatic scaling of AMPARs elicited by chronic activity suppression. To probe the physiological function for ITGβ3-dependent processes in the brain, we examined whether the loss of ITGβ3 affected fear-related behaviours in mice. ITGβ3-knockout (KO) mice showed normal conditioned fear responses that were similar to those of control wild-type mice. However, anxiety-like behaviour appeared substantially compromised and could be reversed to control levels by lentivirus-mediated re-expression of ITGβ3 bilaterally in the ventral hippocampus. In hippocampal slices, the loss of ITGβ3 activity did not compromise Hebbian forms of plasticity - neither acute pharmacological disruption of ITGβ3 ligand interactions nor genetic deletion of ITGβ3 altered long-term potentiation (LTP) or long-term depression (LTD). Moreover, we did not detect any changes in short-term synaptic plasticity upon loss of ITGβ3 activity. In contrast, acutely disrupting ITGβ1-ligand interactions or genetic deletion of ITGβ1 selectively interfered with LTP stabilisation whereas LTD remained unaltered. These findings indicate a lack of requirement for ITGβ3 in the two robust forms of hippocampal long-term synaptic plasticity, LTP and LTD, and suggest differential roles for ITGβ1 and ITGβ3 in supporting hippocampal circuit functions.
    Document Type:
    Reference
    Product Catalog Number:
    MAB1501
    Product Catalog Name:
    Anti-Actin Antibody, clone C4

  • ΔFosB induction in striatal medium spiny neuron subtypes in response to chronic pharmacological, emotional, and optogenetic stimuli. 24259563

    The transcription factor, ΔFosB, is robustly and persistently induced in striatum by several chronic stimuli, such as drugs of abuse, antipsychotic drugs, natural rewards, and stress. However, very few studies have examined the degree of ΔFosB induction in the two striatal medium spiny neuron (MSN) subtypes. We make use of fluorescent reporter BAC transgenic mice to evaluate induction of ΔFosB in dopamine receptor 1 (D1) enriched and dopamine receptor 2 (D2) enriched MSNs in ventral striatum, nucleus accumbens (NAc) shell and core, and in dorsal striatum (dStr) after chronic exposure to several drugs of abuse including cocaine, ethanol, Δ(9)-tetrahydrocannabinol, and opiates; the antipsychotic drug, haloperidol; juvenile enrichment; sucrose drinking; calorie restriction; the serotonin selective reuptake inhibitor antidepressant, fluoxetine; and social defeat stress. Our findings demonstrate that chronic exposure to many stimuli induces ΔFosB in an MSN-subtype selective pattern across all three striatal regions. To explore the circuit-mediated induction of ΔFosB in striatum, we use optogenetics to enhance activity in limbic brain regions that send synaptic inputs to NAc; these regions include the ventral tegmental area and several glutamatergic afferent regions: medial prefrontal cortex, amygdala, and ventral hippocampus. These optogenetic conditions lead to highly distinct patterns of ΔFosB induction in MSN subtypes in NAc core and shell. Together, these findings establish selective patterns of ΔFosB induction in striatal MSN subtypes in response to chronic stimuli and provide novel insight into the circuit-level mechanisms of ΔFosB induction in striatum.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple

  • 1-Aminoindan-1,5-dicarboxylic acid and (S)-(+)-2-(3'-carboxybicyclo[1.1.1] pentyl)-glycine, two mGlu1 receptor-preferring antagonists, reduce neuronal death in in vitro a ... 10564371

    Metabotropic glutamate (mGlu) receptors have been implicated in a number of physiological and pathological responses to glutamate, but the exact role of group I mGlu receptors in causing postischaemic injury is not yet clear. In this study, we examined whether the recently-characterized and relatively selective mGlu1 receptor antagonists 1-aminoindan-1,5-dicarboxylic acid (AIDA) and (S)-(+)-2-(3'-carboxybicyclo[1.1.1]pentyl)-glycine (CBPG) could reduce neuronal death in vitro, following oxygen-glucose deprivation (OGD) in murine cortical cell and rat organotypic hippocampal cultures, and in vivo, after global ischaemia in gerbils. When present in the incubation medium during the OGD insult and the subsequent 24 h recovery period, AIDA and CBPG significantly reduced neuronal death in vitro. The extent of protection was similar to that observed with the nonselective mGlu receptor antagonist (+)-alpha-methyl-4-carboxyphenylglycine [(+)MCPG] and with typical ionotropic glutamate (iGlu) receptor antagonists. Neuroprotection was also observed when AIDA or CBPG were added only after the OGD insult was terminated. Neuronal injury was not attenuated by the inactive isomer (-)MCPG, but was significantly enhanced by the nonselective mGlu receptor agonist (1S,3R)-1-aminocyclopentane-1, 3-dicarboxylic acid [(1S,3R)-ACPD] and the group I mGlu receptor agonist 3,5-dihydroxyphenylglycine (3,5-DHPG). The antagonists (+)MCPG, AIDA and CBPG were also neuroprotective in vivo, because i. c.v. administration reduced CA1 pyramidal cell degeneration examined 7 days following transient carotid occlusion in gerbils. Our results point to a role of mGlu1 receptors in the pathological mechanisms responsible for postischaemic neuronal death and propose a new target for neuroprotection.
    Document Type:
    Reference
    Product Catalog Number:
    13-107
    Product Catalog Name:
    Core Histones

  • 1-methyl-4-phenylpyridinium (MPP+) decreases mitochondrial oxidation-reduction (REDOX) activity and membrane potential (Deltapsi(m)) in rat striatum. 12504872

    Mitochondrial dysfunction has long been implicated in the death of nigrostriatal dopaminergic neurons in Parkinson's disease (PD) and its experimental models. Here we further analyzed changes in the mitochondrial oxidation-reduction (REDOX) activity and membrane potential (Deltapsi(m)) of striatal synaptosomes after the infusion of 1-methyl-4-phenylpyridinium (MPP+) into rat striatum. MPP+ (40 nmol) treatment produced decreases in mitochondrial REDOX activity and Deltapsi(m) at 18 h, as measured by fluorometric analysis with both Alamar blue and JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolyl-carbocyanine iodide) dyes. At this time point, tyrosine hydroxylase (TH) and dopamine transporter (DAT) protein levels were not altered, but both decreased at 7 days after MPP+ (40 nmol) infusion. Both measures of mitochondrial dysfunction induced by MPP+ (40 nmol) at 18 h were attenuated, at least in part, by pretreatment with a selective dopamine uptake inhibitor GBR-12909 (1-(2-(bis(4-fluorophenyl)methoxy)ethyl)-4-(3-phenylpropyl) piperazine). In addition, GBR-12909 partially attenuated MPP+ (40 nmol)-caused a loss of striatal nerve terminal as indicated by decreases in TH and DAT immunoreactivities as well as dopamine and its metabolites levels. The present study indicates that decreases in mitochondrial REDOX activity and Deltapsi(m) may play a role in MPP+ -induced dopaminergic neurotoxicity, and further provides that improvement of mitochondrial dysfunction may be a better way to slow progressive dopaminergic neurodegeneration commonly associated with PD.
    Document Type:
    Reference
    Product Catalog Number:
    AB1591P
    Product Catalog Name:
    Anti-Dopamine Transporter Antibody