Interaction between the Alzheimer's survival peptide humanin and insulin-like growth factor-binding protein 3 regulates cell survival and apoptosis.
Insulin-like growth factor-binding protein-3 (IGFBP-3) regulates IGF bioactivity and also independently modulates cell growth and survival. By using a yeast two-hybrid screen to identify IGFBP-3-interacting proteins, we cloned humanin (HN) as an IGFBP-3-binding partner. HN is a 24-aa peptide that has been shown to specifically inhibit neuronal cell death induced by familial Alzheimer's disease mutant genes and amyloid-beta (Abeta). The physical interaction of HN with IGFBP-3 was determined to be of high affinity and specificity and was confirmed by yeast mating, displaceable pull-down experiments with (His)-6-tagged HN, and ligand blot experiments. Co-immunoprecipitation of IGFBP-3 and HN from mouse testes confirmed the interaction in vivo. In cross-linking experiments, HN bound IGFBP-3 but did not compete with IGF-I-IGFBP-3 binding; competitive ligand dot blot experiments revealed the 18-aa heparin-binding domain of IGFBP-3 as the binding site for HN. Alanine scanning determined that F6A-HN mutant does not bind IGFBP-3. HN but not F6A-HN inhibited IGFBP-3-induced apoptosis in human glioblastoma-A172. In contrast, HN did not suppress IGFBP-3 response in SH-SY5Y neuroblastoma and mouse cortical primary neurons. In primary neurons, IGFBP-3 markedly potentiated HN rescue ability from Abeta1-43 toxicity. In summary, we have identified an interaction between the survival peptide HN and IGFBP-3 that is pleiotrophic in nature and is capable of both synergistic and antagonistic interaction. This interaction may prove to be important in neurological disease processes and could provide important targets for drug development.
Ikonen
Maaria
M
Department of Pediatrics, Mattel Children's Hospital, University of California, Los Angeles, CA 90095.
Liu
Bingrong
B
Hashimoto
Yuichi
Y
Ma
Liqun
L
Lee
Kuk-Wha
KW
Niikura
Takako
T
Nishimoto
Ikuo
I
Cohen
Pinchas
P
D000409:Alanine; D000544:Alzheimer Disease / Q000235:genetics / Q000473:pathology; D000595:Amino Acid Sequence; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000235:genetics / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016366:Open Reading Frames; D011506:Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism
D018972:Insulin-Like Growth Factor Binding Protein 3; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; D011994:Recombinant Proteins; C427211:humanin; D000409:Alanine