title: Restricted expression of new guanine nucleotide exchange factor Zizimin2 in aged acquired immune system.
abstract: The activity of various biological functions, such as nervous, endocrine and immune systems including acquired immunity, is known to decline along with aging. To elucidate the molecular mechanism of this phenomenon, we here compared the number of thymocytes, splenocytes, and bone marrow lymphocytes in young and aged mice and found the age-related functional fragility of the immune system. However, the molecular mechanisms or even the key molecules remain elusive. Therefore, we further focused on a candidate for immunosenesence-related molecules, Zizimin2, which we have recently isolated and identified as a novel guanine nucleotide exchange factor that is highly expressed in murine splenic germinal center B cells after immunization with a T cell-dependent antigen. Here, we showed that endogenous Zizimin2 protein as well as mRNA expression levels in immune organs are strictly suppressed in aged mice. We further observed that the serum antigen specific antibody response is hampered in aged mice compared to that in young animals. Moreover, the Zizimin2 mRNA expression level was not activated after immunization in aged mice. Taken together, these data suggested that Zizimin2 is associated with the reduction of immune response in acquired immunity along with aging.
authors.affiliation: Department of Mechanism of Aging, Research Institute, National Center for Geriatrics and Gerontology, 35, Gengo, Morioka-machi, Obu, Aichi 474-8511, Japan.
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Jia
authors.forename: Isamu
authors.initials: I
authors.lastname: Sakabe
authors.forename: Takenori
authors.initials: T
authors.lastname: Matsuda
authors.forename: Tomoko
authors.initials: T
authors.lastname: Hayakawa
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Maruyama
mesh_terms: D056704:Adaptive Immunity / Q000502:physiology; D000375:Aging / Q000378:metabolism; D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism; D015153:Blotting, Western; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D016133:Polymerase Chain Reaction
chemical_list: C498343:Dock11 protein, mouse; D020662:Guanine Nucleotide Exchange Factors