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.
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.
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.