title: Mapping of the interaction site between sortilin and the p75 neurotrophin receptor reveals a regulatory role for the sortilin intracellular domain in p75 neurotrophin receptor shedding and apoptosis.
abstract: Neurotrophins comprise a group of neuronal growth factors that are essential for the development and maintenance of the nervous system. However, the immature pro-neurotrophins promote apoptosis by engaging in a complex with sortilin and the p75 neurotrophin receptor (p75(NTR)). To identify the interaction site between sortilin and p75(NTR), we analyzed binding between chimeric receptor constructs and truncated p75(NTR) variants by co-immunoprecipitation experiments, surface plasmon resonance analysis, and FRET. We found that complex formation between sortilin and p75(NTR) relies on contact points in the extracellular domains of the receptors. We also determined that the interaction critically depends on an extracellular juxtamembrane 23-amino acid sequence of p75(NTR). Functional studies further revealed an important regulatory function of the sortilin intracellular domain in p75(NTR)-regulated intramembrane proteolysis and apoptosis. Thus, although the intracellular domain of sortilin does not contribute to p75(NTR) binding, it does regulate the rates of p75(NTR) cleavage, which is required to mediate pro-neurotrophin-stimulated cell death.
authors.affiliation: Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Sune
authors.initials: S
authors.lastname: Skeldal
authors.forename: Alex M
authors.initials: AM
authors.lastname: Sykes
authors.forename: Simon
authors.initials: S
authors.lastname: Glerup
authors.forename: Dusan
authors.initials: D
authors.lastname: Matusica
authors.forename: Nickless
authors.initials: N
authors.lastname: Palstra
authors.forename: Henri
authors.initials: H
authors.lastname: Autio
authors.forename: Zoran
authors.initials: Z
authors.lastname: Boskovic
authors.forename: Peder
authors.initials: P
authors.lastname: Madsen
authors.forename: Eero
authors.initials: E
authors.lastname: Castrén
authors.forename: Anders
authors.initials: A
authors.lastname: Nykjaer
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Coulson
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D045744:Cell Line, Tumor; D057809:HEK293 Cells; D006801:Humans; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010449:Peptide Mapping; D017434:Protein Structure, Tertiary; D059748:Proteolysis; D051381:Rats; D017475:Receptors, Nerve Growth Factor / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020349:Surface Plasmon Resonance; D000099183:Sortilin
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D009419:Nerve Tissue Proteins; D017475:Receptors, Nerve Growth Factor; D011993:Recombinant Fusion Proteins; D000099183:Sortilin; C484065:NGFR protein, human