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Mike Fainzilber

Publications and source records attributed to Mike Fainzilber.

24 records · Page 2Linked to original sources
PubMed2002

The p75 neurotrophin receptor interacts with multiple MAGE proteins.

The p75 neurotrophin receptor has been implicated in diverse aspects of neurotrophin signaling, but the mechanisms by which its effects are mediated are not well understood. Here we identify two MAGE proteins, necdin and MAGE-H1, as interactors for the intracellular domain of p75 and show that the interaction is enhanced by ligand stimulation. PC12 cells transfected with necdin or MAGE-H1 exhibit accelerated differentiation in response to nerve growth factor. Expression of these two MAGE proteins is predominantly cytoplasmic in PC12 cells, and necdin was found to be capable of homodimerization, suggesting that it may act as a cytoplasmic adaptor to recruit a signaling complex to p75. These findings indicate that diverse MAGE family members can interact with the p75 receptor and highlight type II MAGE proteins as a potential family of interactors for signaling proteins containing type II death domains.

Animals↗
PubMed2002

Rabies virus glycoprotein (RVG) is a trimeric ligand for the N-terminal cysteine-rich domain of the mammalian p75 neurotrophin receptor.

Rabies virus glycoprotein (RVG) is a trimeric and surface-exposed viral coat protein that has been shown to interact with the murine p75 neurotrophin receptor. We have investigated binding of RVG to p75 and describe several features that distinguish the p75-RVG interaction from conventional neurotrophin binding to p75. RVG binds mammalian but not avian p75 and does not bind to any of the Trk neurotrophin receptors. The mammalian p75 specificity of RVG binding may partly explain the phyletic specificity of rabies infection. Radioiodinated nerve growth factor (NGF) and RVG both bind to rat p75 but do not compete with each other's binding site. Although neurotrophins bind to the second and third cysteine-rich domains (CRD) of p75, RVG specifically interacts with high affinity (K(d) 30-35 pm) with the first CRD (CRD1). Substitution of Gln(33) in p75-CRD1 by Glu completely abolishes RVG binding. Our data therefore firmly establish RVG as a trimeric high affinity ligand for a non-neurotrophin binding site on p75. Interestingly, the CRD1 in another TNF/NGF family receptor was recently shown to be involved in the binding of the herpes virus glycoprotein gD, suggesting that the CRD1 of TNF/NGF family members may be a widely used binding domain for viral glycoproteins.

Amino Acid Sequence↗
PubMed2002

Genetic models meet trophic mechanisms: EGF family members are gliatrophins in Drosophila.

Trophic survival mechanisms are crucial for the determination of cell numbers in the developing vertebrate nervous system, but important neurotrophic factor families such as the neurotrophins have not yet been found in either Drosophila or C. elegans. Two independent studies on distinct glial populations in Drosophila have now shown that their survival is regulated by EGF family members secreted by adjacent neurons. Fly genetics thus promises new insights on trophic signaling mechanisms and confirms that trophic regulation of cell survival is an evolutionarily ancient mechanism for building the nervous system.

Animals↗
PubMed2002

Nerve growth factor-induced p75-mediated death of cultured hippocampal neurons is age-dependent and transduced through ceramide generated by neutral sphingomyelinase.

Binding of nerve growth factor (NGF) to the p75 neurotrophin receptor (p75) in cultured hippocampal neurons has been reported to cause seemingly contrasting effects, namely ceramide-dependent axonal outgrowth of freshly plated neurons, versus Jun kinase (Jnk)-dependent cell death in older neurons. We now show that the apoptotic effects of NGF in hippocampal neurons are observed only from the 2nd day of culture onward. This switch in the effect of NGF is correlated with an increase in p75 expression levels and increasing levels of ceramide generation as the cultures mature. NGF application to neuronal cultures from p75(exonIII-/-) mice had no effect on ceramide levels and did not affect neuronal viability. The neutral sphingomyelinase inhibitor, scyphostatin, inhibited NGF-induced ceramide generation and neuronal death, whereas hippocampal neurons cultured from acid sphingomyelinase(-/-) mice were as susceptible to NGF-induced death as wild type neurons. The acid ceramidase inhibitor, (1S,2R)-d-erythro-2-(N-myristoylamino)-1-phenyl-1-propanol, enhanced cell death, supporting a role for ceramide itself and not a downstream lipid metabolite. Finally, scyphostatin inhibited NGF-induced Jnk phosphorylation in hippocampal neurons. These data indicate an initiating role of ceramide generated by neutral sphingomyelinase in the diverse neuronal responses induced by binding of neurotrophins to p75.

Age Factors↗