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  • K252a suppresses neuronal cells apoptosis through inhibiting the translocation of bax to Mitochondria induced by the MLK3JNK signaling after transient global brain ischem ... 21726169

    It is demonstrated that the c-Jun N-terminal kinase (JNK) signaling pathway plays a critical role in ischemic brain injury. Our previous studies have suggested that K252a can obviously inhibit JNK activation induced by ischemia/reperfusion in the vulnerable hippocampal CA1 subregion. Here, we further discussed the potential mechanism of ischemic brain injury induced by the activation of JNK after 15?min of transient global cerebral ischemia. As a result, through inhibiting phosphorylation of Bcl-2 (a cytosolic target of JNK) and 14-3-3 protein (a cytoplasmic anchor of Bax) induced by the activation of JNK, K252a decreased the release of Bax from Bcl-2/Bax and 14-3-3/Bax dimers, further attenuating the translocation of Bax from cytosol to mitochondria and the release of cytochrome c induced by ischemia/reperfusion, which related to mitochondria-mediated apoptosis. Importantly, pre-infusion of K2525a 20?min before ischemia showed neuroprotective effect against neuronal cells apoptosis. These findings imply that K252a induced neuroprotection against ischemia/reperfusion in rat hippocampal CA1 subregion via inhibiting the mitochondrial apoptosis pathway induced by JNK activation.
    Document Type:
    Reference
    Product Catalog Number:
    S7100
    Product Catalog Name:
    ApopTag® Peroxidase In Situ Apoptosis Detection Kit

  • Impaired Ganglioside Metabolism in Huntington's Disease and Neuroprotective Role of GM1. 20237277

    Huntington's disease (HD) is a neurodegenerative disorder caused by the expansion of a polyglutamine stretch in the protein huntingtin (Htt). HD neurons are dysfunctional at multiple levels and have increased susceptibility to stress and apoptotic stimuli. We have discovered that synthesis of the ganglioside GM1 is reduced in fibroblasts from HD patients and in cell and animal models of HD, and that decreased GM1 levels contribute to heighten HD cell susceptibility to apoptosis. The apoptotic susceptibility is recapitulated through inhibition of ganglioside synthesis in wild-type striatal cells, suggesting that decreased GM1 levels might be one of the key events leading to HD pathogenesis and progression. Administration of GM1 restores ganglioside levels in HD cells and promotes activation of AKT and phosphorylation of mutant Htt, leading to decreased mutant Htt toxicity and increased survival of HD cells. Our data identify GM1 as a potential treatment for HD.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple

  • Rac1b regulates NT3-stimulated Mek-Erk signaling, directing marrow-isolated adult multilineage inducible (MIAMI) cells toward an early neuronal phenotype. 22061968

    Due to the limitations of neural stem cells to repair neuronal damage in the human brain, alternative approaches of repair using autologous adult stem cells have been examined for direct cell-replacement, or paracrine mediated neuroprotective effects. Human bone marrow-derived stromal cells (hMSCs) are a heterogeneous adult stem cell population with diverse immunomodulatory properties and the potential to differentiate into cells characteristic of all three germ layers. hMSCs are a renewable source of progenitor cells suitable for cell-based tissue repair. The marrow isolated adult multilineage inducible (MIAMI) cells developed by our laboratory are a developmentally immature homogeneous subpopulation of hMSCs that maintain self-renewal potential during ex vivo expansion, efficient differentiation capacity into neuron-like cells in vitro, as well as direct in vivo neuroprotection and functional recovery in animal models of neurological diseases. We now address the early signaling mechanisms regulating the neuron-like differentiation of MIAMI cells in vitro, in response to activation of the neurotrophic tyrosine-kinase receptor, type 3 (NTRK3) via neurotrophin 3 (NT3). We molecularly characterize a novel role for Rac1b mediating the neurogenic potential of MIAMI cells. Rac1b had an overall negative modulatory effect on the NT3-stimulated Mek1/2-Erk1/2 signaling pathway, proneuronal gene expression and neurite-like extensions. Rac1b was required for NT3-stimulated cell proliferation of MIAMI cells, yet was found to repress CCND1 and CCNB1 mRNA expression independent of NT3 stimulation, suggesting a dual neurotrophin dependent/independent function. Differential levels of Rac1b activity in hMSCs may explain the apparent contradictory reports regarding their neurogenic potential. These findings demonstrate the in vitro neurogenic potential of hMSCs as governed by Rac1b during NT3 stimulation.
    Document Type:
    Reference
    Product Catalog Number:
    09-271
    Product Catalog Name:
    Anti-Rac1b Antibody

  • A tropomyosine receptor kinase inhibitor blocks spinal neuroplasticity essential for the anti-hypersensitivity effects of gabapentin and clonidine in rats with peripheral ... 20638911

    Spinally released brain-derived nerve growth factor (BDNF) after nerve injury is essential to anatomic and functional changes in spinal noradrenergic and cholinergic systems, which are engaged or targeted by commonly used treatments for neuropathic pain. Since BDNF signals via tropomyosine receptor kinases (trks), we tested whether trk blockade by repeated spinal injection of the trk inhibitor K252a would reduce anatomical (spinal noradrenergic and cholinergic fiber density), functional (α2-adrenoceptor-mediated direct stimulation of spinal cholinergic terminals), and behavioral (anti-hypersensitivity from systemic gabapentin and spinal clonidine) plasticity, which depends on BDNF. Spinal K252a treatment did not alter hypersensitivity from spinal nerve ligation (SNL), but blocked the SNL-associated increase in dopamine-β-hydroxylase (DβH) fiber density in the spinal cord dorsal horn while reducing spinal choline acetyltransferase (ChAT)-immunoreactivity. K252a treatment also abolished the facilitatory effect of dexmedetomidine on KCl-evoked acetylcholine release in spinal cord synaptosomes and reduced the anti-hypersensitivity effects of oral gabapentin and spinal clonidine. These results suggest that spinal trk signaling is essential for the anatomic and functional plasticity in noradrenergic and cholinergic systems after nerve injury and consequently for the analgesia from drugs that rely on these systems.Many drugs approved for neuropathic pain engage spinal noradrenergic and cholinergic systems for analgesia. This study demonstrates that spinal trk signaling after nerve injury is important to neuroplasticity of these systems, which is critical for the analgesic action of common treatments for neuropathic pain.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple

  • Polysialic acid limits choline acetyltransferase activity induced by brain-derived neurotrophic factor. 16903870

    Choline acetyltransferase (ChAT), the enzyme synthesizing acetylcholine, is known to be activated by brain derived neurotrophic factor (BDNF). We found that the specific removal of the carbohydrate polysialic acid (PSA) significantly increased BDNF-induced ChAT-activity in embryonic septal neurons. Using a p75 neurotrophin receptor (p75(NTR)) function-blocking antibody and K252a, a-pan tropomyosin related kinase (Trk) inhibitor, we demonstrate that BDNF-induced ChAT activity requires the stimulation of p75(NTR) and TrkB. PSA removal drastically increased radioactive iodinated ([(125)I])BDNF's maximal binding capacity (Bmax), derived from concentrations of [(125)I]BDNF ranging from 1 pM to 3.2 nM. In the presence of unlabeled nerve growth factor to prevent the binding of [(125)I]BDNF to p75(NTR) sites, the impact of PSA removal on the binding capacity of [(125)I]BDNF was greatly reduced. In conclusion, PSA limits BDNF-induced ChAT activity and BDNF-receptor interactions. BDNF-induced ChAT activity is TrkB and p75(NTR) dependent, and upon PSA removal the additional binding of BDNF to its receptors, especially p75(NTR), likely contributes to the maximal ChAT activity observed. In vivo, the ontogenetic loss of PSA in the postnatal period may allow more interactions between BDNF and its receptors to increase ChAT activity and assure the proper development of the cholinergic septal neurons.
    Document Type:
    Reference
    Product Catalog Number:
    AB5312
    Product Catalog Name:
    Anti-Growth Associated Protein 43 Antibody

  • Chick sympathetic neurons in culture respond differentially to nerve growth factor and conditioned medium from activated splenic lymphocytes. 1645462

    Chicken splenic cells, stimulated by concanavalin A, secreted a factor or factors into the culture medium which supported the survival of neurons from sympathetic ganglia of chick embryos. The effect of this conditioned medium (CM) was similar to the effect of nerve growth factor (NGF). However, the enhanced survival effect of CM was unaffected by K-252a, a protein kinase inhibitor which completely abolished the effect of NGF. 6-Thioguanine, an inhibitor of NGF-activated protein kinase N, blocked the survival effects of both NGF and CM on sympathetic neurons, but a dose required for the half-maximal inhibition for the survival effect of CM was 10 times higher than that for NGF. H-7, an inhibitor of protein kinase C, did not block the effect of either CM or NGF. On the other hand, the survival effect of both CM and NGF was blocked to the same extent by 5'-deoxy-5'-methylthioadenosine and LiCl. These results suggest that activated splenic cells secreted neuronal survival-promoting factor(s) into CM and that the cellular mechanisms promoting neuronal survival by CM are different from those promoting neuronal survival induced by NGF.
    Document Type:
    Reference
    Product Catalog Number:
    03-100
    Product Catalog Name:
    RIPAb+™ hnRNP M1-M4

  • BDNF-induced synaptic delivery of AMPAR subunits is differentially dependent on NMDA receptors and requires ERK. 18977306

    Previous studies using an in vitro model of eyeblink classical conditioning in turtles suggest that increased numbers of synaptic AMPARs supports the acquisition and expression of conditioned responses (CRs). Brain-derived neurotrophic factor (BDNF) and its associated receptor tyrosine kinase, TrkB, is also required for acquisition of CRs. Bath application of BDNF alone induces synaptic delivery of GluR1- and GluR4-containing AMPARs that is blocked by coapplication of the receptor tyrosine kinase inhibitor K252a. The molecular mechanisms involved in BDNF-induced AMPAR trafficking remain largely unknown. The aim of this study was to determine whether BDNF-induced synaptic AMPAR incorporation utilizes similar cellular mechanisms as AMPAR trafficking that occurs during in vitro classical conditioning. Using pharmacological blockade and confocal imaging, the results show that synaptic delivery of GluR1 subunits during conditioning or BDNF application does not require activity of NMDARs but is mediated by extracellular signal-regulated kinase (ERK). In contrast, synaptic delivery of GluR4-containing AMPARs during both conditioning and BDNF application is NMDAR- as well as ERK-dependent. These findings indicate that BDNF application mimics AMPAR trafficking observed during conditioning by activation of some of the same intracellular signaling pathways and suggest that BDNF is a key signal transduction element in postsynaptic events that mediate conditioning.
    Document Type:
    Reference
    Product Catalog Number:
    06-308

  • Upregulation of CREB-mediated transcription enhances both short- and long-term memory. 21677163

    Unraveling the mechanisms by which the molecular manipulation of genes of interest enhances cognitive function is important to establish genetic therapies for cognitive disorders. Although CREB is thought to positively regulate formation of long-term memory (LTM), gain-of-function effects of CREB remain poorly understood, especially at the behavioral level. To address this, we generated four lines of transgenic mice expressing dominant active CREB mutants (CREB-Y134F or CREB-DIEDML) in the forebrain that exhibited moderate upregulation of CREB activity. These transgenic lines improved not only LTM but also long-lasting long-term potentiation in the CA1 area in the hippocampus. However, we also observed enhanced short-term memory (STM) in contextual fear-conditioning and social recognition tasks. Enhanced LTM and STM could be dissociated behaviorally in these four lines of transgenic mice, suggesting that the underlying mechanism for enhanced STM and LTM are distinct. LTM enhancement seems to be attributable to the improvement of memory consolidation by the upregulation of CREB transcriptional activity, whereas higher basal levels of BDNF, a CREB target gene, predicted enhanced shorter-term memory. The importance of BDNF in STM was verified by microinfusing BDNF or BDNF inhibitors into the hippocampus of wild-type or transgenic mice. Additionally, increasing BDNF further enhanced LTM in one of the lines of transgenic mice that displayed a normal BDNF level but enhanced LTM, suggesting that upregulation of BDNF and CREB activity cooperatively enhances LTM formation. Our findings suggest that CREB positively regulates memory consolidation and affects memory performance by regulating BDNF expression.
    Document Type:
    Reference
    Product Catalog Number:
    AB1513P
    Product Catalog Name:
    Anti-Brain Derived Neurotrophic Factor Antibody

  • Initiation of testicular tubulogenesis is controlled by neurotrophic tyrosine receptor kinases in a three-dimensional Sertoli cell aggregation assay. 18660385

    The first morphological sign of testicular differentiation is the formation of testis cords. Prior to cord formation, newly specified Sertoli cells establish adhesive junctions, and condensation of somatic cells along the surface epithelium of the genital ridge occurs. Here, we show that Sertoli cell aggregation is necessary for subsequent testis cord formation, and that neurotrophic tyrosine kinase receptors (NTRKs) regulate this process. In a three-dimensional cell culture assay, immature rat Sertoli cells aggregate to form large spherical aggregates (81.36+/-7.34 microm in diameter) in a highly organized, hexagonal arrangement (376.95+/-21.93 microm average distance between spherical aggregates). Exposure to NTRK inhibitors K252a and AG879 significantly disrupted Sertoli cell aggregation in a dose-dependent manner. Sertoli cells were prevented from establishing cell-cell contacts and from forming spherical aggregates. In vitro-derived spherical aggregates were xenografted into immunodeficient nude mice to investigate their developmental potential. In controls, seminiferous tubule-like structures showing polarized single-layered Sertoli cell epithelia, basement membranes, peritubular myoid cells surrounding the tubules, and lumen were observed in histological sections. By contrast, grafts from treatment groups were devoid of tubules and only few single Sertoli cells were present in xenografts after 4 weeks. Furthermore, the grafts were significantly smaller when Sertoli cell aggregation was disrupted by K252a in vitro (20.87 vs 6.63 mg; Pless than 0.05). We conclude from these results that NTRK-regulated Sertoli-Sertoli cell contact is essential to the period of extensive growth and remodeling that occurs during testicular tubulogenesis, and our data indicate its potential function in fetal and prepubertal testis differentiation.
    Document Type:
    Reference
    Product Catalog Number:
    AB1244