title: Metallothionein and a peptide modeled after metallothionein, EmtinB, induce neuronal differentiation and survival through binding to receptors of the low-density lipoprotein receptor family.
abstract: Accumulating evidence suggests that metallothionein (MT)-I and -II promote neuronal survival and regeneration in vivo. The present study investigated the molecular mechanisms underlying the differentiation and survival-promoting effects of MT and a peptide modeled after MT, EmtinB. Both MT and EmtinB directly stimulated neurite outgrowth and promoted survival in vitro using primary cultures of cerebellar granule neurons. In addition, expression and surface localization of megalin, a known MT receptor, and the related lipoprotein receptor-related protein-1 (LRP) are demonstrated in cerebellar granule neurons. By means of surface plasmon resonance MT and EmtinB were found to bind to both megalin and LRP. The bindings were abrogated in the presence of receptor-associated protein-1, an antagonist of the low-density lipoprotein receptor family, which also inhibited MT- and EmtinB-induced neurite outgrowth and survival. MT-mediated neurite outgrowth was furthermore inhibited by an anti-megalin serum. EmtinB-mediated inhibition of apoptosis occurred without a reduction of caspase-3 activity, but was associated with reduced expression of the pro-apoptotic B-cell leukemia/lymphoma-2 interacting member of cell death (Bim(S)). Finally, evidence is provided that MT and EmtinB activate extracellular signal-regulated kinase, protein kinase B, and cAMP response element binding protein. Altogether, these results strongly suggest that MT and EmtinB induce their neuronal effects through direct binding to surface receptors belonging to the low-density lipoprotein receptor family, such as megalin and LRP, thereby activating signal transduction pathways resulting in neurite outgrowth and survival.
authors.affiliation: Protein Laboratory, Institute of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Malene
authors.initials: M
authors.lastname: Ambjørn
authors.forename: Johanne W
authors.initials: JW
authors.lastname: Asmussen
authors.forename: Mats
authors.initials: M
authors.lastname: Lindstam
authors.forename: Kamil
authors.initials: K
authors.lastname: Gotfryd
authors.forename: Christian
authors.initials: C
authors.lastname: Jacobsen
authors.forename: Vladislav V
authors.initials: VV
authors.lastname: Kiselyov
authors.forename: Søren K
authors.initials: SK
authors.lastname: Moestrup
authors.forename: Milena
authors.initials: M
authors.lastname: Penkowa
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Bock
authors.forename: Vladimir
authors.initials: V
authors.lastname: Berezin
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D002454:Cell Differentiation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D004305:Dose-Response Relationship, Drug; D020287:In Situ Nick-End Labeling / Q000379:methods; D036341:Intercellular Signaling Peptides and Proteins; D026563:LDL-Receptor Related Protein-Associated Protein / Q000378:metabolism; D026561:Low Density Lipoprotein Receptor-Related Protein-2 / Q000378:metabolism; D008668:Metallothionein / Q000737:chemistry / Q000494:pharmacology*; D008954:Models, Biological; D016501:Neurites / Q000187:drug effects; D009474:Neurons / Q000187:drug effects*; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D011485:Protein Binding / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D011973:Receptors, LDL / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D020349:Surface Plasmon Resonance / Q000379:methods
chemical_list: C550242:EmtinB peptide; D036341:Intercellular Signaling Peptides and Proteins; D026563:LDL-Receptor Related Protein-Associated Protein; D026561:Low Density Lipoprotein Receptor-Related Protein-2; D010455:Peptides; D011973:Receptors, LDL; D008668:Metallothionein