Meiotic and mitotic functions of mammalian RAD 18 in DNA double-strand break repair

This thesis focuses on the role of RAD 18 in DNA double-strand break (DSB ) repair. Much is known about the role of RAD 18, and its critical substrate PCNA in replication damage bypass (RDB ) repair. However, the roles of RAD 18 in DSB repair are still elusive, although several interaction partners of RAD 18 have been identified, and the radiation-sensitivity of Rad18 knockout cells has shown that this E3 ligase is active in DSB repair. First, a general introduction on the possible involvement of RAD 18 in DSB repair mechanisms and RDB that operate in mitotic and meiotic cells is presented in Chapter 1. In Chapter 2, we examined the dynamic localization of human RAD 18 during the cell cycle and after DNA damage in living cells. The DNA damage response functio

統合失調症を持つ人に対する精神科看護師によるアドヒアランス・セラピーの効果 : 無作為化比較試験

学位の種別:課程博士University of Tokyo(東京大学

Lactobacillus Acidophilus Strain L-92 Regulates the Production of Th1 Cytokine as well as Th2 Cytokines

ABSTRACTBackgroundThere is growing interest in probiotics such as lactic acid bacteria (LAB), not only for treatment of T helper type (Th) 1-mediated diseases but also for Th2-mediated diseases, including allergic diseases, since lactic acid bacteria may be able to modulate the Th1/Th2 balance, in addition to having an immunomodulative effect through induction of Th1 bias.MethodsThe effect of oral administration of heat-killed Lactobacillus acidophilus Strain L-92 (L-92) on ovalbumin (OVA)-specific immunoglobulin (Ig)E production was investigated in BALB/c mice. L-92 was orally administered to mice for 8 weeks from 2 weeks after initiation of OVA-immunization. Patterns of cytokine and Ig production in splenocytes and cells from Peyer’s patches (PPs) from these mice were examined after restimulation with OVA in vitro.ResultsL-92 significantly suppressed serum OVA-specific IgE levels for a long period. Cytokines such as interferon (IFN)-γ, interleukin (IL)-4 and IL-10 and Igs such as total IgE and OVA-specific IgE were produced at significantly lower levels by splenocytes of L-92-treated mice, compared with those of control mice. In contrast, transforming growth factor (TGF)-β and IgA levels produced by PPs from L-92-treated mice were significantly higher than in those from control mice.ConclusionsOral L-92 administration regulated both Th1 and Th2 cytokine responses, suppressed serum OVA-specific IgE, and induced TGF-β production in PPs. TGF-β is known to be associated with activation of regulatory T (Treg) cells. These data suggest that LAB may have immunomodulative effect by Treg cells via TGF-β activity

Free fatty acid receptors, G protein-coupled receptor 120 and G protein-coupled receptor 40, are essential for oil-induced gastric inhibitory polypeptide secretion

Aims/Introduction: Incretin hormone glucose‐dependent insulinotropic polypeptide/gastric inhibitory polypeptide (GIP) plays a key role in high‐fat diet‐induced obesity and insulin resistance. GIP is strongly secreted from enteroendocrine K cells by oil ingestion. G protein‐coupled receptor (GPR)120 and GPR40 are two major receptors for long chain fatty acids, and are expressed in enteroendocrine K cells. In the present study, we investigated the effect of the two receptors on oil‐induced GIP secretion using GPR120‐ and GPR40‐double knockout (DKO) mice. Materials and Methods: Global knockout mice of GPR120 and GPR40 were crossbred to generate DKO mice. Oral glucose tolerance test and oral corn oil tolerance test were carried out. For analysis of the number of K cells and gene expression in K cells, DKO mice were crossbred with GIP‐green fluorescent protein knock‐in mice in which visualization and isolation of K cells can be achieved. Results: Double knockout mice showed normal glucose‐induced GIP secretion, but no GIP secretion by oil. We then investigated the number of K cells and gene characteristics in K cells isolated from GIP‐green fluorescent protein knock‐in mice. Deficiency of both receptors did not affect the number of K cells in the small intestine or expression of GIP messenger ribonucleic acid in K cells. Furthermore, there was no significant difference in the expression of the genes associated with lipid absorption or GIP secretion in K cells between wild‐type and DKO mice. Conclusions: Oil‐induced GIP secretion is triggered by the two major fatty acid receptors, GPR120 and GPR40, without changing K‐cell number or K‐cell characteristics

Regulation of histone H3K4 tri-methylation and PAF complex recruitment by the Ccr4-Not complex

Efficient transcription is linked to modification of chromatin. For instance, tri-methylation of lysine 4 on histone H3 (H3K4) strongly correlates with transcriptional activity and is regulated by the Bur1/2 kinase complex. We found that the evolutionarily conserved Ccr4-Not complex is involved in establishing H3K4 tri-methylation in Saccharomyces cerevisiae. We observed synthetic lethal interactions of Ccr4-Not components with BUR1 and BUR2. Further analysis indicated that the genes encoding the Not-proteins are essential for efficient regulation of H3K4me3, but not H3K4me1/2, H3K36me2 or H3K79me2/3 levels. Moreover, regulation of H3K4me3 levels by NOT4 is independent of defects in RNA polymerase II loading. We found NOT4 to be important for ubiquitylation of histone H2B via recruitment of the PAF complex, but not for recruitment or activation of the Bur1/2 complex. These results suggest a mechanism in which the Ccr4-Not complex functions parallel to or downstream of the Bur1/2 kinase to facilitate H3K4me3 via PAF complex recruitment

Repair of exogenous DNA double-strand breaks promotes chromosome synapsis in SPO11-mutant mouse meiocytes, and is altered in the absence of HORMAD1

Repair of SPO11-dependent DNA double-strand breaks (DSBs) via homologous recombination (HR) is essential for stable homologous chromosome pairing and synapsis during meiotic prophase. Here, we induced radiation-induced DSBs to study meiotic recombination and homologous chromosome pairing in mouse meiocytes in the absence of SPO11 activity (Spo11YF/YF model), and in the absence of both SPO11 and HORMAD1 (Spo11/Hormad1 dko). Within 30 min after 5 Gy irradiation of Spo11YF/YF mice, 140–160 DSB repair foci were detected, which specifically localized to the synaptonemal complex axes. Repair of radiation-induced DSBs was incomplete in Spo11YF/YF compared to Spo11+/YF meiocytes. Still, repair of exogenous DSBs promoted partial recovery of chromosome pairing and synapsis in Spo11YF/YF meiocytes. This indicates that at least part of the exogenous DSBs can be processed in an interhomolog recombination repair pathway. Interestingly, in a seperate experiment, using 3 Gy of irradiation, we observed that Spo11/Hormad1 dko spermatocytes contained fewer remaining DSB repair foci at 48 h after irradiation compared to irradiated Spo11 knockout spermatocytes. Together, these results show that recruitment of exogenous DSBs to the synaptonemal complex, in conjunction with repair of exogenous DSBs via the homologous chromosome, contributes to homology recognition. In addition, the data suggest a role for HORMAD1 in DNA repair pathway choice in mouse meiocytes

Enzymatically modified isoquercitrin supplementation intensifies plantaris muscle fiber hypertrophy in functionally overloaded mice

BackgroundEnzymatically modified isoquercitrin (EMIQ) is produced from rutin using enzymatic hydrolysis followed by treatment with glycosyltransferase in the presence of dextrin to add glucose residues. EMIQ is absorbed in the same way as quercetin, a powerful antioxidant reported to prevent disused muscle atrophy by targeting mitochondria and to have ergogenic effects. The present study investigated the effect of EMIQ on skeletal muscle hypertrophy induced by functional overload.MethodsIn Study 1, 6-week-old ICR male mice were divided into 4 groups: sham-operated control, sham-operated EMIQ, overload-operated control, and overload-operated EMIQ groups. In Study 2, mice were divided into 3 groups: overload-operated whey control, overload-operated whey/EMIQ (low dose), and overload-operated whey/EMIQ (high dose) groups. The functional overload of the plantaris muscle was induced by ablation of the synergist (gastrocnemius and soleus) muscles. EMIQ and whey protein were administered with food. Three weeks after the operation, the cross-sectional area and minimal fiber diameter of the plantaris muscle fibers were measured.ResultsIn Study 1, functional overload increased the cross-sectional area and minimal fiber diameter of the plantaris muscle. EMIQ supplementation significantly increased the cross-sectional area and minimal fiber diameter of the plantaris muscle in both the sham-operated and overload-operated groups. In Study 2, EMIQ supplementation combined with whey protein administration significantly increased the cross-sectional area and minimal fiber diameter of the plantaris muscle.ConclusionEMIQ, even when administered as an addition to whey protein supplementation, significantly intensified the fiber hypertrophy of the plantaris muscle in functionally overloaded mice. EMIQ supplementation also induced fiber hypertrophy of the plantaris in sham-operated mice