Identification of the Neogenin-Binding Site on the Repulsive Guidance Molecule A

Repulsive guidance molecule (RGM) is a membrane-bound protein that was originally identified as an axon guidance molecule in the chick retinotectal system. RGMa, one of the 3 isoforms found in mammals, is involved in laminar patterning, cephalic neural tube closure, axon guidance, and inhibition of axonal regeneration. In addition to its roles in the nervous system, RGMa plays a role in enhancing helper T-cell activation. Binding of RGM to its receptor, neogenin, is considered necessary to transduce these signals; however, information on the binding of RGM to neogenin is limited. Using co-immunoprecipitation studies, we have identified that the RGMa region required for binding to neogenin contains amino acids (aa) 259–295. Synthesized peptide consisting of aa 284–293 directly binds to the extracellular domain (ECD) of recombinant neogenin, and addition of this peptide inhibits RGMa-induced growth cone collapse in mouse cortical neurons. Thus, we propose that this peptide is a promising lead in finding reagents capable of inhibiting RGMa signaling

神経因性疼痛の発症にWnt/βカテニンシグナルが関与する

京都大学0048新制・課程博士博士(医学)甲第18149号医博第3869号新制||医||1002(附属図書館)31007京都大学大学院医学研究科医学専攻(主査)教授 福田 和彦, 教授 渡邉 大, 教授 河野 憲二学位規則第4条第1項該当Doctor of Medical ScienceKyoto UniversityDFA

Temporal changes in cell marker expression and cellular infiltration in a controlled cortical impact model in adult male C57BL/6 mice.

BACKGROUND: Traumatic injury to the central nervous system (CNS) triggers a robust inflammatory response that leads to axonal damage and secondary degeneration of spared tissue. In contrast, some immune responses have neuroprotective effects. However, detailed information regarding the dynamics of immune responses after traumatic CNS injury is still unavailable. METHODS: In the present study, changes in the immune cells present in the injured brain, spleen, and cervical lymph nodes (CLNs), which are draining lymphatic organs from the CNS, were analyzed after controlled cortical impact (CCI) by flow cytometry and immunohistochemistry. RESULTS: The number of neutrophils and macrophages that infiltrated the injured brain immediately increased 1 d post-injury and declined rapidly thereafter. In the injured brain, resident microglia showed a bimodal increase during the first week and in the chronic phase (≥3 weeks) after injury. Increase in the Iba-1(+) microglia/macrophages was observed around the injured site. Morphologic analysis showed that Iba-1(+) cells were round at 1 week, whereas those at 3 weeks were more ramified. Furthermore, CD86(+)/CD11b(+) M1-like microglia increased at 4 weeks after CCI, whereas CD206(+)/CD11b(+) M2-like microglia increased at 1 week. These results suggest that different subsets of microglia increased in the acute and chronic phases after CCI. Dendritic cells and T cells increased transiently within 1 week in the injured brain. In the CLNs and the spleen, T cells showed dynamic changes after CCI. In particular, the alteration in the number of T cells in the CLNs showed a similar pattern, with a 1-week delay, to that of microglia in the injured brain. CONCLUSION: The data from this study provide useful information on the dynamics of immune cells in CNS injuries

Neutrophils and macrophages in the spleen after CCI.

<p>A: Dot plots of immune cells in the spleen for live cell analysis. B: Representative cytometry data for neutrophils in the spleen at the indicated days after CCI. C: Representative cytometry data for macrophages in the spleen at the indicated days after CCI. D: Graph illustrating quantitative data for neutrophils and macrophages in the CLNs after CCI. <i>n</i> = 3–5 for each experiment. Neutrophils: ** <i>p</i><0.01 at 28 dpi compared with no injury.</p

Neutrophils and macrophages in the CLNs after CCI.

<p>A: Dot plots of immune cells in the CLNs for live cell analysis. B: Representative cytometry data for neutrophils in the CLNs at the indicated days after CCI. C: Representative cytometry data for CD45⁺/CD11b⁺ macrophages in the CLNs at the indicated days after CCI. D: Graph illustrating quantitative data for neutrophils and macrophages in the CLNs after CCI. <i>n</i> = 3–4 for each experiment. Neutrophils: ** <i>p</i><0.01 at 1 and 14 dpi compared with no injury; macrophages: ** <i>p</i><0.01 at 7, 14, and 21 dpi compared with 1 dpi.</p

T cells and DCs in the cervical lymph nodes

<p>(<b>CLNs</b>) <b>after CCI.</b> A: Representative cytometry data for T cells in the CLNs at the indicated days after CCI. B: Graph illustrating quantitative data for T cells in the CLNs after CCI. C: Representative cytometry data for DCs in the CLNs at the indicated days after CCI. D: Graph illustrating quantitative data for DCs in the CLNs after CCI. (B, D) <i>n</i> = 3–4 for each experiment. T cells: * <i>p</i><0.05 at 28 dpi compared with 1 dpi; DCs: ** <i>p</i><0.01 at 3 dpi compared with no injury, * <i>p</i><0.05 at 7, 14, and 21 dpi compared with no injury.</p

Changes in specific subsets of microglia in the injured brain.

<p>A: Representative cytometry data showing the purity of microglia isolated. Of the isolated cells, 91% were microglia. B: Representative cytometry data for CD86⁺/CD11b⁺ M1-like microglia in the brain at the indicated days after CCI. C: Representative cytometry data for CD206⁺/CD11b⁺ M2-like microglia in the brain at the indicated days after CCI. D: Graph illustrating quantitative data for CD86⁺/CD11b⁺ cells in the brain after CCI. CD86⁺/CD11b⁺ cells were higher in number than in the intact brain at 28 dpi. E: Graph illustrating quantitative data for CD206⁺/CD11b⁺ cells in the brain after CCI. CD206⁺/CD11b⁺ cells were higher in number at 7 dpi than in the intact brain, and decreased thereafter until 28 dpi. <i>n</i> = 3–5 for each group. * <i>p</i><0.05 compared with no injury.</p