title: Age-related guanine nucleotide exchange factor, mouse Zizimin2, induces filopodia in bone marrow-derived dendritic cells.
abstract: BACKGROUND
  We recently isolated and identified Zizimin2 as a functional factor that is highly expressed in murine splenic germinal center B cells after immunization with T-cell-dependent antigen. Zizimin2 was revealed to be a new family member of Dock (dedicator of cytokinesis), Dock11, which is the guanine nucleotide exchange factor for Cdc42, a low-molecular-weight GTPase. However, the molecular function of Zizimin2 in acquired immunity has not been elucidated.
  
  
  RESULTS
  In this study, we show that the protein expression of Zizimin2, which is also restricted to lymphoid tissues and lymphocytes, is reduced in aged mice. Over-expression of full-length Zizimin2 induced filopodial formation in 293T cells, whereas expression of CZH2 domain inhibited it. Stimulation of Fcγ receptor and Toll-like receptor 4 triggered Zizimin2 up-regulation and Cdc42 activation in bone marrow-derived dendritic cells.
  
  
  CONCLUSIONS
  These data suggest that Zizimin2 is an immune-related and age-regulated guanine nucleotide exchange factor, which facilitates filopodial formation through activation of Cdc42, which results in activation of cell migration.
authors.affiliation: Department of Mechanism of Aging, Research Institute - National Center for Geriatrics and Gerontology, 35, Gengo, Morioka-Machi, Obu-city, Aichi 474-8511, Japan. michan@ncgg.go.jp.
authors.forename: Isamu
authors.initials: I
authors.lastname: Sakabe
authors.forename: Azusa
authors.initials: A
authors.lastname: Asai
authors.forename: Junko
authors.initials: J
authors.lastname: Iijima
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Maruyama