Age-related guanine nucleotide exchange factor, mouse Zizimin2, induces filopodia in bone marrow-derived dendritic cells

<p>Abstract</p> <p>Background</p> <p>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.</p> <p>Results</p> <p>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.</p> <p>Conclusions</p> <p>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.</p

Manzamenone O, New Trimeric Fatty Acid Derivative from a Marine Sponge <i>Plakortis</i> sp.

A new structurally unique trimeric fatty acid derivative, manzamenone O (<b>1</b>), was isolated from a marine sponge <i>Plakortis</i> sp. Manzamenone O (<b>1</b>) has a novel skeleton consisting of C–C bonded octahydroindenone and dioxabicyclo[3.3.0]octane moieties and three long aliphatic chains. The structure of <b>1</b> was elucidated on the basis of spectroscopic data and conformational analysis. Manzamenone O (<b>1</b>) exhibited antimicrobial activity against <i>Micrococcus luteus</i>, <i>Aspergillis niger</i>, and <i>Trichophyton mentagrophytes</i>

Osteopetrosis and thalamic hypomyelinosis with synaptic degeneration in DAP12-deficient mice

Deletions in the DAP12 gene in humans result in Nasu-Hakola disease, characterized by a combination of bone fractures and psychotic symptoms similar to schizophrenia, rapidly progressing to presenile dementia. However, it is not known why these disorders develop upon deficiency in DAP12, an immunoreceptor signal activator protein initially identified in the immune system. Here we show that DAP12-deficient (DAP12(–/–)) mice develop an increased bone mass (osteopetrosis) and a reduction of myelin (hypomyelinosis) accentuated in the thalamus. In vitro osteoclast induction from DAP12(–/–) bone marrow cells yielded immature cells with attenuated bone resorption activity. Moreover, immature oligodendrocytes were arrested in the vicinity of the thalamus, suggesting that the primary defects in DAP12(–/–) mice are the developmental arrest of osteoclasts and oligodendrocytes. In addition, the mutant mice also showed synaptic degeneration, impaired prepulse inhibition, which is commonly observed in several neuropsychiatric diseases in humans including schizophrenia, and aberrant electrophysiological profiles in the thalami. These results provide a molecular basis for a unique combination of skeletal and psychotic characteristics of Nasu-Hakola disease as well as for schizophrenia and presenile dementia

Intratumoral expression levels of PD-L1, GZMA, and HLA-A along with oligoclonal T cell expansion associate with response to nivolumab in metastatic melanoma

Immune checkpoint inhibitors blocking the interaction between programmed death-1 (PD-1) and PD-1 ligand-1 (PD-L1) are revolutionizing the cancer immunotherapies with durable clinical responses. Although high expression of PD-L1 in tumor tissues has been implicated to correlate with the better response to the anti-PD-1 therapies, this association has been controversial. In this study, to characterize immune microenvironment in tumors, we examined mRNA levels of immune-related genes and characterized T cell repertoire in the tumors of 13 melanoma patients before and after nivolumab treatment. We found that, in addition to the PD-L1 (p = 0.03), expression levels of PD-1 ligand-2 (PD-L2), granzyme A (GZMA) and human leukocyte antigen-A (HLA-A) in the pre-treatment tumors were significantly higher (p = 0.04, p = 0.01 and p = 0.006, respectively) in responders (n = 5) than in non-responders (n = 8). With nivolumab treatment, tumors in responders exhibited a substantial increase of CD8, GZMA and perforin 1 (PRF1) expression levels as well as increased ratio of TBX21/GATA3, suggesting dominancy of helper T cell type 1 (Th1) response to type 2 (Th2) response. T cell receptor β (TCR-β) repertoire analysis revealed oligoclonal expansion of tumor-infiltrating T lymphocytes (TILs) in the tumor tissues of the responders. Our findings suggest that melanoma harboring high PD-1 ligands (PD-L1 and PD-L2), GZMA and HLA-A expression may respond preferentially to nivolumab treatment, which can enhance Th1-skewed cellular immunity with oligoclonal expansion of TILs.ArticleONCOIMMUNOLOGY.5(9):e1204507(2016)journal articl