Role of recA/RAD51 family proteins in mammals.

DNA damage causes chromosomal instability leading to oncogenesis, apoptosis, and severe failure of cell functions. The DNA repair system includes base excision repair, nucleotide excision repair, mismatch repair, translesion replication, non-homologous end-joining, and recombinational repair. Homologous recombination performs the recombinational repair. The RAD51 gene is an ortholog of Esherichia coli recA, and the gene product Rad51 protein plays a central role in the homologous recombination. In mammals, 7 recA-like genes have been identified: RAD51, RAD51L1/B, RAD51L2/C, RAD51L3/D, XRCC2, XRCC3, and DMC1. These genes, with the exception of meiosis-specific DMC1, are essential for development in mammals. Disruption of the RAD51 gene leads to cell death, whereas RAD51L1/B, RAD51L2/C, RAD51L3/D, XRCC2, and XRCC3 genes (RAD51 paralogs) are not essential for viability of cells, but these gene-deficient cells exhibit a similar defective phenotype. Yeast two-hybrid analysis, co-immunoprecipitation, mutation analysis, and domain mapping of Rad51 and Rad51 paralogs have revealed protein-protein interactions among these gene products. Recent investigations have shown that Rad51 paralogs play a role not only in an early step, but also in a late step of homologous recombination. In addition, identification of alternative transcripts of some RAD51 paralogs may reflect the complexity of the homologous recombination system.</p

Relativistic mean-field model with density-dependent meson-nucleon couplings

Within the relativistic mean-field approach, we extend the Miyazaki model, where the NN$\sigma$ and NN$\omega$ interactions are modified to suppress the couplings between positive- and negative-energy states of a nucleon in matter. Assuming appropriate density-dependence of the meson-nucleon couplings, we study nuclear matter and finite nuclei. The model can reproduce the observed properties of $^{16}$O and $^{40}$Ca well. We also examine if the model is natural.Comment: 6 pages, 3 figure

DNA rearrangement activity during retinoic acid-induced neural differentiation of P19 mouse embryonal carcinoma cells.

Because of the many superficial similarities between the immune system and the central nervous system, it has long been speculated that somatic DNA recombination is, like the immune system, involved in brain development and function. To examine whether or not the V(D)J recombination signals of the immune system work in an in vitro neural differentiation model, the P19 mouse embryonal carcinoma cell line was transfected with a reporter gene that is designed, when rearranged, to express bacterial beta-galactosidase, which was previously reported to exhibit somatic DNA recombination in the transgenic mouse brain. The cloned cells were then induced into neural cells by retinoic acid treatment. This neural induction treatment resulted in the cloning of a P19 cell line that showed a high incidence of beta-galactosidase-positive cells. Most of these beta-galactosidase-positive cells were immunocytochemically identified as either neurons, neuroepithelial cells, or astrocytes. The 5'-end sequences of the beta-galactosidase transcripts expressed in the induced cells were analyzed, and sequences were found that seemed to reflect DNA rearrangement through re-integration of the reporter gene into the host genome. However, the V(D)J recombination signals did not work in the in vitro model. These results suggested that DNA rearrangement activity though integration increased during neural differentiation of P19 cells.</p

Determination of phenylacetic acid in cerebrospinal fluid by gas chromatography-mass spectrometry.

Using gas chromatography-mass spectrometry, we developed a sensitive and reliable technique to measure phenylacetic acid (PAA), an oxidatively deaminated metabolite of beta-phenylethylamine (PEA), in small amounts of cerebrospinal fluid (CSF). In a preliminary analysis, PAA concentrations in depressive patients were significantly lower than those in controls, while there were no differences in PAA levels between schizophrenic patients and controls. This suggests a possible link between the decreased PEA metabolism in the brain and the etiology of depression. However, further studies are needed to clarify the effects of neuroleptics and antidepressants on PAA levels in CSF, since the samples were obtained without regard to medication in the present study. In control subjects, a U-shaped distribution was obtained when the values of PAA were plotted as a function of age. There were no sex differences and no significant concentration gradients in CSF PAA levels.</p

Cross-talk between IL-6 and TGF-β signaling in hepatoma cells

AbstractInterleukin-6 (IL-6) is a multifunctional cytokine that plays important roles in the immune system, hematopoiesis, and acute phase reactions. Transforming growth factor-β (TGF-β) also has pleiotropy including the production of acute phase proteins in hepatocytes. To elucidate the cross-talk between IL-6 and TGF-β signaling pathways in hepatic cells, we investigated the effects of TGF-β on IL-6-induced signal transducer and activator of transcription-3 (STAT3) activation in a human hepatoma cell line, Hep3B. IL-6-induced activation of STAT3 activity and STAT3-mediated gene expression were augmented by TGF-β in Hep3B cells. We provide evidence that these activities were due to physical interactions between STAT3 and Sma- and MAD-related protein-3, bridged by p300. These results demonstrate a molecular mechanism of a cross-talk between STAT3 and TGF-β signaling pathways in hepatocytes

Tuning Neutron Resonance Spin-Echo Spectrometers with Pulsed Beams

The neutron spin-echo spectroscopy technique involving pulsed beams can be used to effectively access a wide range of space-time correlations of condensed matter. In this study, the features of this technique, in particular, the modulation of the intensity with zero effort (MIEZE) by using pulsed beams, which is based on the quantum-state manipulation of the neutron spin and energy, are comprehensively examined. A formulation of the MIEZE combined with the time of flight method (TOF MIEZE) is established by considering the characteristics of the pulsed neutron beams. Moreover, a parameter, namely, the detuning parameter, is introduced as a measure of the magnitude of detuning from the optimized instrumental state, known as the spin-echo condition. The phase and frequency shifts of the neutron intensity signals resulting from the TOF MIEZE under various configurations are investigated systematically. It is found that the detuning parameter equals the derivative of phase with respect to the TOF, whose zero-point corresponds to the spin-echo condition. The theoretical predictions on phase and frequency shifts by the established formulation are well validated by the experiments using an intense pulsed neutron source. The detuning parameter helps clarify the principle of the TOF MIEZE technique and can provide practical guidance regarding the implementation and optimization of spectrometers

Generation of active oxygen species by iron nitrilotriacetate (Fe-NTA).

Ferric nitrilotriacetate (Fe3+-NTA) solution showed maximum absorbance at pH 7.5. The iron was in ferric high-spin state and coordinated octahedrally with a relatively symmetric structure and also probably pentagonally. A spin trapping technique employing 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) yielded a DMPO spin adduct of unknown radical with three doublets (DMPO-Z) and a simple nitroxide radical (Y-NO.) in serum from rats injected intraperitoneally with Fe3+-NTA. When the Fe3+-NTA solution was diluted 500-fold with 50 mM NTA solution, DMPO-Z, Y-NO. and an additional signal, DMPO-OH were observed. The DMPO-Z signal was suppressed by a decrease in oxygen tension, alpha-tocopherol and 3-tert-butyl-4-hydroxy-anisole (BHA). The DMPO-OH signal was suppressed in the presence of ethanol and catalase. Fe2+-NTA solution hardly produced DMPO spin adducts. The Fe3+-NTA solution produced a strong DMPO-OH signal in the presence of H2O2. Rose Bengal solution, a singlet oxygen generating system, produced the same DMPO adducts. Fe3+-NTA reacted with oxygen in solution. The oxygen was activated and might be similar to singlet molecular oxygen. In the presence of H2O2, the Fe3+-NTA solution generated a hydroxyl radical. Fe3+-NTA itself generated free radicals, but Fe2+-NTA did not.</p

Effect of long-term storage on monoamine metabolite levels in human cerebrospinal fluid.

Concentrations of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) were measured in human cerebrospinal fluid (CSF) following long-term storage at -20 degrees C for intervals of three to 60 months. No significant changes in HVA levels were detected in CSF stored for up to 60 months. On the other hand, 5-HIAA concentrations remained stable for up to 6 months, but decreased significantly in the specimens stored for longer time intervals. The results indicate that 5-HIAA should be determined within 6 months after CSF collection, while HVA determinations may be delayed.</p

シングルセルRNAシーケンシングによる1,25-ジヒドロキシビタミンD3反応性Fgf23発現骨細胞の同定

Fibroblast growth factor 23 (FGF23), a hormone, mainly produced by osteocytes, regulates phosphate and vitamin D metabolism. By contrast, 1,25-dihydroxyvitamin D3, the active form of vitamin D, has been shown to enhance FGF23 production. While it is likely that osteocytes are heterogenous in terms of gene expression profiles, specific subpopulations of Fgf23-expressing osteocytes have not been identified. Single-cell RNA sequencing (scRNA-seq) technology can characterize the transcriptome of an individual cell. Recently, scRNA-seq has been used for bone tissue analysis. However, owing to technical difficulties associated with isolation of osteocytes, studies using scRNA-seq analysis to characterize FGF23-producing osteocytes are lacking. In this study, we characterized osteocytes secreting FGF23 from murine femurs in response to calcitriol (1,25-dihydroxyvitamin D3) using scRNA-seq. We first detected Dmp1, Mepe, and Phex expression in murine osteocytes by in situ hybridization and used these as marker genes of osteocytes. After decalcification, enzyme digestion, and removal of CD45+ cells, femoral bone cells were subjected to scRNA-seq. We identified cell clusters containing osteocytes using marker gene expression. While Fgf23 expression was observed in some osteocytes isolated from femurs of calcitriol-injected mice, no Fgf23 expression was detected in untreated mice. In addition, the expression of several genes which are known to be changed after 1,25-dihydroxyvitamin D3 treatment such as Ccnd2, Fn1, Igfbp7, Pdgfa, and Timp1 was also affected by calcitriol treatment in Fgf23-expressing osteocytes, but not in those lacking Fgf23 expression, even after calcitriol administration. Furthermore, box-and-whisker plots indicated that Fgf23 expression was observed in osteocytes with higher expression levels of the Fam20c, Dmp1, and Phex genes, whose inactivating mutations have been shown to cause FGF23-related hypophosphatemic diseases. These results indicate that osteocytes are heterogeneous with respect to their responsiveness to 1,25-dihydroxyvitamin D3, and sensitivity to 1,25-dihydroxyvitamin D3 is one of the characteristics of osteocytes with Fgf23 expression. It is likely that there is a subpopulation of osteocytes expressing several genes, including Fgf23, involved in phosphate metabolism