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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.

Abstract Background The tuberculosis (TB) still increases in the number of new cases, which is estimated to approach 10 million in 2010. The number of aged people has been growing all over the world. Ageing is one of risk factors in tuberculosis because of decreased immune responses in aged people. Mycobacterium bovis Bacillus Calmette Guérin (BCG) is a sole vaccine currently used for TB, however, the efficacy of BCG in adults is still a matter of debate. Emerging the multidrug resistant Mycobacterium tuberculosis (MDR-TB) make us to see the importance of vaccination against TB in new light. In this study, we evaluated the efficacy of BCG vaccination in aged mice. Results The Th1 responses, interferon-γ production and interleukin 2, in BCG inoculated aged mice (24-month-old) were comparable to those of young mice (4- to 6-week-old). The protection activity of BCG in aged mice against Mycobacterium tuberculosis H37Rv was also the same as young mice. Conclusion These findings suggest that vaccination in aged generation is still effective for protection against tuberculosis.

We recently isolated and identified Zizimin2 as a functional factor that is highly expressed in murine splenic germinal center B cell after immunization with T-cell-dependent antigen. Zizimin2 was revealed that it is a new family member of Dock (dedicator of cytokinesis), Dock11, which was the guanine nucleotide exchange factor for Cdc42, the Rho family of low molecular weight GTPases. However, neither the molecular function of Zizimin2 in the acquired immunity nor the physiological role in decrease of immunological activity along with aging has been known. To facilitate the further analysis of physiological function of this molecule, we have established rat monoclonal antibodies (MAbs) against mouse Zizimin2 protein. Recombinant His-tagged partial mouse Zizimin2 protein was expressed in Escherichia coli, purified, and applied as an antigen for immunization. The desired hybridomas were selected by the recombinant Zizimin2 protein coated enzyme-linked immunosorbent assay screening, and we generated stable hybridoma cell lines that produced the antibody against murine Zizimin2 protein. We determined their isotypes and further examined capability or availability in immunoblotting, immunoprecipitation, or immunofluorescence microscopy. Here we demonstrated the several appropriate antibodies for immunoblotting and immunofluorescence microscopy. These MAbs should therefore be very useful tools for study of the characterization of the Zizimin2 protein and the understanding of the biological function of Zizimin2-mediated immunosenescence. [ABSTRACT FROM AUTHOR]

Senescent cells contribute to tissue aging and underlie the pathology of chronic diseases. The benefits of eliminating senescent cells have been demonstrated in several disease models, and the efficacy of senolytic drugs is currently being tested in humans. Exercise training has been shown to reduce cellular senescence in several tissues; however, the mechanisms responsible remain unclear. We found that myocyte-derived factors significantly extended the replicative lifespan of fibroblasts, suggesting that myokines mediate the anti-senescence effects of exercise. A number of proteins within myocyte-derived factors were identified by mass spectrometry. Among these, pigment epithelium-derived factor (PEDF) exerted inhibitory effects on cellular senescence. Eight weeks of voluntary running increased Pedf levels in skeletal muscles and suppressed senescence markers in the lungs. The administration of PEDF reduced senescence markers in multiple tissues and attenuated the decline in respiratory function in the pulmonary emphysema mouse model. We also showed that blood levels of PEDF inversely correlated with the severity of COPD in patients. Collectively, these results strongly suggest that PEDF contributes to the beneficial effects of exercise, potentially suppressing cellular senescence and its associated pathologies.

Aging is an extremely complex biological process, and various models, from unicellular organisms to mammals, have been used in its research. The mouse is the most widely used model for studying human aging and diseases due to its high homology and well-established strategies for genetic manipulation. Despite these advantages, the maximum lifespan of laboratory mice is nearly three years, which makes it time-consuming to obtain animals of the desired age. To avoid this issue and efficiently conduct aging research, the National Center for Geriatrics and Gerontology operates its "Aging Farm", a system that supplies aged animals in response to researchers' requests. In the present study, as part of the Aging Farm project, we examined changes in the physiological functions of the lungs and gene expression in lung tissues of Aging Farm animals as they aged. A decline in the physiological function of the lungs was already apparent before 6 months of age, and it continued until at least 1 year of age. On the other hand, gene expression profiling by RNA sequencing showed small changes in the early stages of aging but more pronounced changes at 12 and 24 months of age than at 3 months of age. Age-related lung tissue changes are considered to be involved in the pathogenesis of various chronic respiratory diseases, and the characterization of animals as they age will ensure the quality of the Aging Farm as a resource for aging research.

Senescent cells accumulate in many tissues as animals age and are considered to underlie several aging-associated pathologies. The tumor suppressors p19 ARF and p16 INK4a , both of which are encoded in the CDKN2A locus, play critical roles in inducing and maintaining permanent cell cycle arrest during cellular senescence. Although the elimination of p16 INK4a -expressing cells extends the life span of the mouse, it is unclear whether tissue function is restored by the elimination of senescent cells in aged animals and whether and how p19 ARF contributes to tissue aging. The aging-associated decline in lung function is characterized by an increase in compliance as well as pathogenic susceptibility to pulmonary diseases. We herein demonstrated that pulmonary function in 12-month-old mice was reversibly restored by the elimination of p19 ARF -expressing cells. The ablation of p19 ARF -expressing cells using a toxin receptor-mediated cell knockout system ameliorated aging-associated lung hypofunction. Furthermore, the aging-associated gene expression profile was reversed after the elimination of p19 ARF . Our results indicate that the aging-associated decline in lung function was, at least partly, attributed to p19 ARF and was recovered by eliminating p19 ARF -expressing cells.