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Neurotrophins


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  • Role of neurotrophins on postnatal neurogenesis in the thalamus: prenatal exposure to ethanol. 21277941

    A second wave of neuronal generation occurs in the ventrobasal nucleus of the rat thalamus (VB) during the first three postnatal weeks. The present study tested the hypotheses (1) that postnatal neurogenesis in the VB is neurotrophin-regulated and (2) that ethanol-induced changes in this proliferation are mediated by neurotrophins. The first studies examined the effects of neurotrophins on the numbers of cycling cells in ex vivo preparations of the VB from 3-day-old rats. The proportion of cycling (Ki-67-positive) VB cells was higher in cultured thalamic slices treated with neurotrophins than in controls. Interestingly, this increase occurred with nerve growth factor (NGF) alone or with a combination of NGF and brain-derived neurotrophic factor (BDNF), but not with BDNF alone. Based on these data, the VBs from young offspring of pregnant rats fed an ethanol-containing or an isocaloric non-alcoholic liquid diet were examined between postnatal day (P) 1 and P31. Studies used enzyme-linked immunosorbent assays and immunoblots to explore the effects of ethanol on the expression of neurotrophins, their receptors, and representative signaling proteins. Ethanol altered the expression of neurotrophins and receptors throughout the first postnatal month. Expression of NGF increased, but there was no change in the expression of BDNF. The high affinity receptors (TrkA and TrkB) were unchanged but ethanol decreased expression of the low affinity receptor, p75. One downstream signaling protein, extracellular signal-regulated kinase (ERK), decreased but Akt expression was unchanged. Thus, postnatal cell proliferation in the VB of young rat pups is neurotrophin-responsive and is affected by ethanol.Copyright © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.
    Dokumententyp:
    Referenz
    Produkbestellnummer:
    Mehrere
    Produktbezeichnung:
    Mehrere

  • Neurotrophins regulate ApoER2 proteolysis through activation of the Trk signaling pathway. 25233900

    ApoER2 and the neurotrophin receptors Trk and p75(NTR) are expressed in the CNS and regulate key functional aspects of neurons, including development, survival, and neuronal function. It is known that both ApoER2 and p75(NTR) are processed by metalloproteinases, followed by regulated intramembrane proteolysis. TrkA activation by nerve growth factor (NGF) increases the proteolytic processing of p75(NTR) mediated by ADAM17. Reelin induces the sheeding of ApoER2 ectodomain depending on metalloproteinase activity. However, it is not known if there is a common regulation mechanism for processing these receptors.We found that TrkA activation by NGF in PC12 cells induced ApoER2 processing, which was dependent on TrkA activation and metalloproteinases. NGF-induced ApoER2 proteolysis was independent of mitogen activated protein kinase activity and of phosphatidylinositol-3 kinase activity. In contrast, the basal proteolysis of ApoER2 increased when both kinases were pharmacologically inhibited. The ApoER2 ligand reelin regulated the proteolytic processing of its own receptor but not of p75(NTR). Finally, in primary cortical neurons, which express both ApoER2 and TrkB, we found that the proteolysis of ApoER2 was also regulated by brain-derived growth factor (BDNF).Our results highlight a novel relationship between neurotrophins and the reelin-ApoER2 system, suggesting that these two pathways might be linked to regulate brain development, neuronal survival, and some pathological conditions.
    Dokumententyp:
    Referenz
    Produkbestellnummer:
    Mehrere
    Produktbezeichnung:
    Mehrere

  • Cytokines, neurotrophins, and oxidative stress in brain disease from mucopolysaccharidosis IIIB. 17139681

    Mucopolysaccharidosis IIIB (MPS IIIB; Sanfilippo syndrome type B) is characterized by profound neurological deterioration. Because a murine model of MPS IIIB disease is available, we focused on analysis of gene expression in the brain and cerebellum of 7-month-old MPS IIIB mice by pathway-specific filter microarrays designed to probe apoptotic-related, neurotrophic signalling molecules and inflammatory cytokines and receptors. Moreover, we extended the analysis with real-time PCR performed at 1, 3, 7 months after birth. Bdnf was down-regulated in the brain but up-regulated in the cerebellum at 7 months of age, both at RNA and at protein levels. Cbln1 presented a threefold increase in the oldest brains while remaining unaltered in the cerebellum. Ccl3, Casp11, gp91(phox), p67(phox), and p47(phox) showed an increased expression in both brain and cerebellum at each examined time point. Ccl3, in particular, exhibited in both organs and at all times tested approximately a tenfold increase in its expression. Insofar as p47(phox), p67(phox), and gp91(phox) are all components of the phagocyte NADPH oxidase, our results suggest the possible involvement of the reactive oxygen species in the genesis of neurodegeneration in MPS IIIB disease.
    Dokumententyp:
    Referenz
    Produkbestellnummer:
    S7101
    Produktbezeichnung:
    ApopTag® Plus Peroxidase In Situ Apoptosis Kit

  • Neurotrophins and other growth factors in the regenerative milieu of proximal nerve stump tips. 10739024

    Classic ideas on mechanisms for axon sprouting and nerve regeneration from peripheral nerves suggest that there is a prominent role for neurotrophin support. There has been comparatively less attention towards features of the regenerative process that develop from the proximal nerve trunk without the support of target tissues or the denervated trunk of a peripheral nerve. We studied early (2-14 d) expression of local growth factors in proximal nerve stump tips of transected sciatic nerves in rats. Immunohistochemical labelling was used to address specific deposition of BDNF, NGF, NT-3, bFGF, CNTF and IGF-1. We observed a unique localisation of BDNF, and to a much lesser extent, NGF in mast cells of injured nerve trunks but they were also observed in intact uninjured nerves. Macrophages did not express either BDNF or NGF. CNTF and IGF-1 were expressed in Schwann cells of intact nerves and stumps. We did not observe bFGF or NT-3 expression in any of the samples we studied. Mast cells may represent an important reservoir of BDNF in peripheral nerves.
    Dokumententyp:
    Referenz
    Produkbestellnummer:
    Mehrere
    Produktbezeichnung:
    Mehrere

  • Dehydroepiandrosterone and neurotrophins favor axonal growth in a sensory neuron-keratinocyte coculture model. 19361476

    We have previously shown that axonal growth from a subset of sensory neurons was promoted by keratinocytes when the two cell types were co-cultured in a low calcium medium. This phenomenon involves the production of one or several diffusible factors. Here we show that the neuritogenic effect of keratinocytes was significantly reduced in the case of rat primary sensory dorsal root ganglion (DRG) neurons, or completely suppressed in the case of the sensory neuron cell line ND7-23, when the activity of neurotrophin receptors (Trk receptors) was blocked with K252a. This trophic effect apparently involved the activation of tyrosine kinase receptors A and B (TrkA and TrkB) expressed by subpopulations of small- to medium-sized DRG neurons, or only of TrkA receptors in the case of ND7-23 neurons. A residual neurite growth promoting effect of keratinocytes persisted in a fraction of DRG neurons after Trk receptor blockade. This effect was mimicked by the steroid dehydroepiandrosterone (DHEA) but not by other steroids such as pregnenolone, progesterone or 17beta-estradiol. The use of pharmacological agents which inhibit different steps of steroidogenesis indicated that DHEA was probably synthesized from cholesterol in keratinocytes. Our results strongly suggest that DHEA might act as a neurotrophic signal derived from keratinocytes to promote axonal outgrowth from a subpopulation of sensory neurons.
    Dokumententyp:
    Referenz
    Produkbestellnummer:
    AB5372
    Produktbezeichnung:
    Anti-Trk B Antibody, pain, a.a. 54-67 rTrkB

  • Site-specific labeling of neurotrophins and their receptors via short and versatile peptide tags. 25426999

    We present a toolbox for the study of molecular interactions occurring between NGF and its receptors. By means of a suitable insertional mutagenesis method we show the insertion of an 8 amino acid tag (A4) into the sequence of NGF and of 12 amino acid tags (A1 and S6) into the sequence of TrkA and P75NTR NGF-receptors. These tags are shortened versions of the acyl and peptidyl carrier proteins; they are here covalently conjugated to the biotin-substituted arm of a coenzyme A (coA) substrate by phosphopantetheinyl transferase enzymes (PPTases). We demonstrate site-specific biotinylation of the purified recombinant tagged neurotrophin, in both the immature proNGF and mature NGF forms. The resulting tagged NGF is fully functional: it can signal and promote PC12 cells differentiation similarly to recombinant wild-type NGF. Furthermore, we show that the insertion of A1 and S6 tags into human TrkA and P75NTR sequences leads to the site-specific biotinylation of these receptors at the cell surface of living cells. Crucially, the two tags are labeled selectively by two different PPTases: this is exploited to reach orthogonal fluorolabeling of the two receptors co-expressed at low density in living cells. We describe the protocols to obtain the enzymatic, site-specific biotinylation of neurotrophins and their receptors as an alternative to their chemical, nonspecific biotinylation. The present strategy has three main advantages: i) it yields precise control of stoichiometry and site of biotin conjugation; ii) the tags used can be functionalized with virtually any small probe that can be carried by coA substrates, besides (and in addition to) biotin; iii) above all it makes possible to image and track interacting molecules at the single-molecule level in living systems.
    Dokumententyp:
    Referenz
    Produkbestellnummer:
    Mehrere
    Produktbezeichnung:
    Mehrere