title: Identification of neurite outgrowth active sites on the laminin alpha4 chain G domain.
abstract: The laminin alpha4 chain is widely distributed in various mesodermal tissues, including the perineurium of peripheral nerves, dorsal root ganglion (DRG), skeletal muscle, and capillaries, and plays important roles in synaptic specialization at the neuromuscular junction and in microvascular formation. The C-terminal globular domain (G domain) of the laminin alpha4 chain was previously found to be critical for heparin binding and cell attachment activity. Here, we focused on neurite outgrowth activity of the laminin alpha4 chain G domain. We found that the recombinant alpha4 chain G domain protein (rec-alpha4G) promoted neurite outgrowth of rat pheochromocytoma PC12 cells. When 114 overlapping synthetic peptides that covered the entire G domain were tested for neurite outgrowth activity, nine peptides were active, but the 105 remaining peptides did not exhibit activity. Three of the nine active peptides, A4G6 (LAIKNDNLVYVY), A4G20 (DVISLYNFKHIY), and A4G107 (VIRDSNVVQLDV), strongly promoted neurite outgrowth of PC12 cells. A4G107 was found to form amyloid-like fibrils in Congo red, X-ray, and electron microscopy analyses. We also synthesized cyclic peptides to evaluate their conformational requirements. Cyclic peptide A4G82X (cyc-A4G82X;TLFLAHGRLVFX, where X is norleucine) significantly enhanced neurite outgrowth activity, but the rest of the cyclic peptides eliminated the activity. The A4G82 sequence is located on the loop region, suggesting that the activity of A4G82 is required for a loop conformation. These peptides also exhibited neurite outgrowth activity with dorsal root ganglion (DRG) explants and with DRG cells from E14.5 mouse embryos, indicating that they are active in both neuronal cell lines and native neuronal cells. Taken together, the data suggest that the peptides from the laminin alpha4 chain G domain promote neurite outgrowth activity via a specific conformation.
authors.affiliation: Research Institute for Diseases of Old Age, Department of Neurology, Juntendo University School of Medicine, Tokyo 113-8421, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Ichikawa
authors.forename: Shingo
authors.initials: S
authors.lastname: Kasai
authors.forename: Nobuharu
authors.initials: N
authors.lastname: Suzuki
authors.forename: Norio
authors.initials: N
authors.lastname: Nishi
authors.forename: Shinya
authors.initials: S
authors.lastname: Oishi
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Fujii
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kadoya
authors.forename: Kozo
authors.initials: K
authors.lastname: Hatori
authors.forename: Yoshikuni
authors.initials: Y
authors.lastname: Mizuno
authors.forename: Motoyoshi
authors.initials: M
authors.lastname: Nomizu
authors.forename: Eri
authors.initials: E
authors.lastname: Arikawa-Hirasawa
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002478:Cells, Cultured; D004396:Coloring Agents; D003224:Congo Red; D007797:Laminin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016501:Neurites / Q000378:metabolism*; D016716:PC12 Cells; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013194:Staining and Labeling
chemical_list: D004396:Coloring Agents; C501370:Lama4 protein, mouse; D007797:Laminin; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D011994:Recombinant Proteins; D003224:Congo Red