Humanin antagonists: mutants that interfere with dimerization inhibit neuroprotection by Humanin

• Published in: The European journal of neuroscience 2004-05, Vol.19 (9), p.2356-2364
• Main Authors: Hashimoto, Yuichi, Terashita, Kenzo, Niikura, Takako, Yamagishi, Yohichi, Ishizaka, Miho, Kanekura, Kohsuke, Chiba, Tomohiro, Yamada, Marina, Kita, Yoshiko, Aiso, Sadakazu, Matsuoka, Masaaki, Nishimoto, Ikuo
• Format: Article
• Language: English
• Subjects: Alzheimer's disease; Amyloid beta-Peptides - toxicity; Amyloid beta-Protein Precursor - adverse effects; Amyloid beta-Protein Precursor - genetics; Animals; Blotting, Western - methods; Cell Count - methods; Cell Death - drug effects; Cell Survival - drug effects; Cerebral Cortex - cytology; Culture Media, Conditioned - pharmacology; Dimerization; Dose-Response Relationship, Drug; Drug Interactions; Hybrid Cells; Intracellular Signaling Peptides and Proteins; Mice; Mutation; Nerve Tissue Proteins - pharmacology; Neuroblastoma; neuronal death; Neurons; Neuropeptides; neuroprotection; Neuroprotective Agents - pharmacology; Oligopeptides; Peptide Fragments - toxicity; Peptides - pharmacology; Proteins - chemistry; Proteins - genetics; Proteins - pharmacology; Rats; Transfection - methods
• ISSN: 0953-816X; 1460-9568
• DOI: 10.1111/j.0953-816X.2004.03298.x

The 24‐residue peptide Humanin (HN) protects neuronal cells from insults of various Alzheimer's disease (AD) genes and Aβ 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.