title: Humanin antagonists: mutants that interfere with dimerization inhibit neuroprotection by Humanin.
abstract: The 24-residue peptide Humanin (HN) protects neuronal cells from insults of various Alzheimer's disease (AD) genes and Abeta by forming a homodimer. We have previously shown that P3A, S7A, C8A, L9A, L12A, T13A, S14A and P19A mutations nullify the neuroprotective function of HN [Yamagishi, Y., Hashimoto, Y., Niikura, T. & Nishimoto, I. (2003) Peptides, 24, 585-595]. Here we examined whether any of these 'null' mutants could function as dominant-negative mutants. Homodimerization-defective mutants, P3A-, L12A-, S14A- and P19A-HN, specifically blocked neuroprotection by HN, but not by activity-dependent neurotrophic factor. Furthermore, insertion of S7A, the mutation that blocks the homodimerization of HN, but not insertion of G5A abolished the antagonizing function of L12A-HN. While L12A-HN and G5A/L12A-HN actually inhibited HN homodimerization, S7A/L12A-HN had no effect. These data indicate that P3A-, L12A-, S14A- and P19A-HN function as HN antagonists by forming an inactive dimer with HN. This study provides a novel insight into the understanding of the in vivo function of HN, as well as into the development of clinically applicable HN neutralizers.
authors.affiliation: Departments of Pharmacology and Anatomy, KEIO University School of Medicine, General Research Building, 3rd and 6th Floors, 35 Shinanomachi, Tokyo 160-8582, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Hashimoto
authors.forename: Kenzo
authors.initials: K
authors.lastname: Terashita
authors.forename: Takako
authors.initials: T
authors.lastname: Niikura
authors.forename: Yohichi
authors.initials: Y
authors.lastname: Yamagishi
authors.forename: Miho
authors.initials: M
authors.lastname: Ishizaka
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Kanekura
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Chiba
authors.forename: Marina
authors.initials: M
authors.lastname: Yamada
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Kita
authors.forename: Sadakazu
authors.initials: S
authors.lastname: Aiso
authors.forename: Masaaki
authors.initials: M
authors.lastname: Matsuoka
authors.forename: Ikuo
authors.initials: I
authors.lastname: Nishimoto
mesh_terms: D016229:Amyloid beta-Peptides / Q000633:toxicity; D016564:Amyloid beta-Protein Precursor / Q000009:adverse effects / Q000235:genetics; D000818:Animals; D015153:Blotting, Western / Q000379:methods; D002452:Cell Count / Q000379:methods; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002540:Cerebral Cortex / Q000166:cytology; D017077:Culture Media, Conditioned / Q000494:pharmacology; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D006822:Hybrid Cells; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000494:pharmacology; D009447:Neuroblastoma; D009474:Neurons; D009479:Neuropeptides; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009842:Oligopeptides; D010446:Peptide Fragments / Q000633:toxicity; D010455:Peptides / Q000494:pharmacology; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D051381:Rats; D014162:Transfection / Q000379:methods
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D017077:Culture Media, Conditioned; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D018696:Neuroprotective Agents; D009842:Oligopeptides; D010446:Peptide Fragments; D010455:Peptides; D011506:Proteins; C410622:activity-dependent neurotrophic factor; C098994:amyloid beta-protein (1-43); C427211:humanin