Katsuki Tsuritani

Social isolation rearing-induced impairment of the hippocampal neurogenesis is associated with deficits in spatial memory and emotion-related behaviors in juvenile mice.

Experiences during brain development may influence the pathogenesis of developmental disorders. Thus, social isolation (SI) rearing after weaning is a useful animal model for studying the pathological mechanisms of such psychiatric diseases. In this study, we examined the effect of SI on neurogenesis in the hippocampal dentate gyrus (DG) relating to memory and emotion‐related behaviors. When newly divided cells were labeled with 5‐bromo‐2′‐deoxyuridine (BrdU) before SI, the number of BrdU‐positive cells and the rate of differentiation into neurons were significantly decreased after 4‐week SI compared with those in group‐housed mice. Repeated treatment of fluoxetine prevented the SI‐induced impairment of survival of newly divided cells and ameliorated spatial memory impairment and part of aggression in SI mice. Furthermore, we investigated the changes in gene expression in the DG of SI mice by using DNA microarray and real‐time PCR. We finally found that SI reduced the expression of development‐related genes Nurr1 and Npas4. These findings suggest that communication in juvenile is important in the survival and differentiation of newly divided cells, which may be associated with memory and aggression, and raise the possibility that the reduced expression of Nurr1 and/or Npas4 may contribute to the impairment of neurogenesis and memory and aggression induced by SI.

Cytokine Receptor-Like Factor 1 is Highly Expressed in Damaged Human Knee Osteoarthritic Cartilage and Involved in Osteoarthritis Downstream of TGF-β

Osteoarthritis (OA) is the most prevalent joint disease and is characterized by pain and functional loss of the joint. However, the pathogenic mechanism of OA remains unclear, and no drug therapy for preventing its progress has been established. To identify genes related to the progress of OA, the gene expression profiles of paired intact and damaged cartilage obtained from OA patients undergoing joint substitution were compared using oligo microarrays. Using functional categorization combined with gene ontology and a statistical analysis, five genes were found to be highly expressed in damaged cartilage (HBEGF, ASUS, CRLF1, LOX, CDA), whereas three genes were highly expressed in intact tissues (CHST2, PTPRD, CPAN6). Among these genes, the upregulated expression of CRLF1 was reconfirmed using real-time PCR, and the in vivo expression of CRLF1 was detected in clusters of chondrocytes and fibrocartilage-like cells in damaged OA cartilages using in situ hybridization. In vitro, the transcriptional level of CRLF1 was positively regulated by TGF-β1 in the mouse chondrogenic cell line ATDC5. Additionally, the CRLF1/CLC complex promoted the proliferation of ATDC5 cells and suppressed the expression level of aggrecan and type II collagen. Our data suggest that the CRLF1/CLC complex disrupts cartilage homeostasis and promotes the progress of OA by enhancing the proliferation of chondrocytes and suppressing the production of cartilage matrix. A component of the complex, CRLF1, may be useful as a biomarker of OA; and the corresponding receptor is a potential new drug target for OA.

Effects of kynurenine metabolites on mesangial cell proliferation and gene expression.

In the present study, we examined the effects of kynurenine metabolites on cultured mesangial cells (MCs) and demonstrated for the first time that they affect MC proliferation and gene expression. Anthranilic acid and 3-hydroxy-DL-kynurenine suppressed MC proliferation by 32% and 43%, respectively at 10(-6) M compared to the control. In contrast, quinolinic acid and l-kynurenine promoted MC proliferation by 49% and 35% at 10(-8) M respectively, although promoting activities declined at higher concentrations. In addition, quinolinic acid upregulated the gene expression of platelet-derived growth factor-B, collagen type-Ialpha1, and collagen type-IValpha1. However, the gene expression of hepatocyte growth factor (HGF) was downregulated. We further examined the gene expressions in the glomeruli of high serum IgA (HIGA) mice with IgA nephropathy using microarray technology and found that the gene expression of insulin-like growth factor-1 was higher, but that of HGF was lower at 40 weeks of age compared to 8 weeks of age. In Balb/c mice, the gene expression of three kynurenine pathway enzymes (kynurenine aminotransferase I, kynurenine aminotransferase II, and quinolinate phospho-ribosyltransferase) increased 2- to 3.5-fold, whereas those in HIGA mice did not change significantly. These results suggest that abnormalities in the kynurenine pathway are associated with the dysfunction of MCs and progression of chronic kidney diseases.

Transcriptional induction and translational inhibition of Arc and Cugbp2 in mice hippocampus after transient global ischemia under normothermic condition

Mild hypothermia protects against neuronal damage after transient global ischemia in experimental animals. The exact mechanism of this protective effect remains to be elucidated. The purpose of the present study was to investigate the molecular mechanisms relevant to different neurologic responses to hypothermia and normothermia. Transient global ischemia was induced in C57BL/6 mice by bilateral common carotid artery occlusion for 10 min. Hypothermia provided robust neuroprotection in the hippocampus region and dramatically reduced the mortality rate. Using adaptor-tagged competitive polymerase chain reaction, we obtained the relative transcription levels of 1210 genes in the hippocampal region and compared the expression patterns of these genes. Two genes, Activity-regulated cytoskeleton-associated protein (Arc) and CUG-binding protein-2 (Cugbp2), showed remarkable and persistent increases in their expression levels in normothermic mice, compared with in both sham and hypothermic mice. Despite the increased transcription of Arc and Cugbp2, an immunohistochemistry analysis did not show comparable increases in the translations of both genes. Only a transient increase in Arc protein was observed in the granule cells of the dentate gyrus at 6 h after reperfusion. A remarkable decrease in Cugbp2 protein was observed in the pyramidal cells of the hippocampal CA1-CA3, in accordance with the progress of neuronal degeneration. A decrease in Cugbp2 protein was not observed in hypothermic mice. These results suggest that transient global ischemia induces the translational inhibition of genes with increased expression not in hypothermic, but in normothermic mice. Thus, translational inhibition might play an important role in the progress of neuronal injury after transient global ischemia.

Japan PGx Data Science Consortium Database: SNPs and HLA genotype data from 2994 Japanese healthy individuals for pharmacogenomics studies

Japan Pharmacogenomics Data Science Consortium (JPDSC) has assembled a database for conducting pharmacogenomics (PGx) studies in Japanese subjects. The database contains the genotypes of 2.5 million single-nucleotide polymorphisms (SNPs) and 5 human leukocyte antigen loci from 2994 Japanese healthy volunteers, as well as 121 kinds of clinical information, including self-reports, physiological data, hematological data and biochemical data. In this article, the reliability of our data was evaluated by principal component analysis (PCA) and association analysis for hematological and biochemical traits by using genome-wide SNP data. PCA of the SNPs showed that all the samples were collected from the Japanese population and that the samples were separated into two major clusters by birthplace, Okinawa and other than Okinawa, as had been previously reported. Among 87 SNPs that have been reported to be associated with 18 hematological and biochemical traits in genome-wide association studies (GWAS), the associations of 56 SNPs were replicated using our data base. Statistical power simulations showed that the sample size of the JPDSC control database is large enough to detect genetic markers having a relatively strong association even when the case sample size is small. The JPDSC database will be useful as control data for conducting PGx studies to explore genetic markers to improve the safety and efficacy of drugs either during clinical development or in post-marketing.

Downregulated expression in high IgA (HIGA) mice and the renal protective role of meprinβ

This study discusses the critical role of the metalloproteinase meprinbeta in the progression of glomerulonephritis. Using a microarray technique, the gene expression profiles in glomeruli isolated from high serum IgA (HIGA) mice with a purity of 97% or greater were examined. HIGA mice are a valid model of human IgA nephropathy (IgAN), with the typical pathological features of this condition, including a consistently high serum IgA level as well as dominant mesangial IgA deposition and mesangial enlargement. Among the many upregulated/downregulated genes after the development of IgAN, the downregulation of meprinbeta was intriguing. The expression level of the meprinbeta gene at 40 weeks of age was 52% of that observed at 8 weeks of age (prior to the development of IgAN), although in the control BALB/c mice, a 2.19-fold elevation was seen. These results were also confirmed by semi-quantitative RT-PCR and immunostaining analyses. As meprinbeta is a subunit of metalloproteinase meprins (meprin A, meprin B) and meprins are capable of proteolytically degrading extracellular matrix (ECM) components and proteolytically processing bioactive peptides, the downregulation of meprinbeta may contribute to the progression of glomerulonephritis and the eventual glomerular scarring. This working hypothesis was examined using an in vivo meprinbeta inhibition study. The inhibition of meprins by actinonin exacerbated some parameters of renal injury in mice afflicted with anti-glomerular basement membrane (anti-GBM) antibody-associated nephritis. These in vitro and in vivo results suggest that meprinbeta may play a protective role against the progression of renal injury through the degradation of ECM and bioactive peptides.

Gene expression analysis in the lung of the rasH2 transgenic mouse at week 4 prior to induction of malignant tumor formation by urethane and N-methylolacrylamide

The rasH2 transgenic (Tg) mice are susceptible to genotoxic and some non-genotoxic carcinogens. In carcinogenicity studies carried out using rasH2 Tg mice, the carcinogenic potential of chemicals are evaluated over a 26-week experimental period. In the present study, we examined the comprehensive gene expressions in the lungs of Tg and non-Tg mice prior to the induction of malignant tumors. Urethane (UR), a mutagenic carcinogen, was administered for 4 weeks, and thereafter withdrawn for 22 weeks. N-methylolacrylamide (NMA), a non-mutagenic carcinogen, was administered for 26 weeks. At week 4, gene expression analysis of non-neoplastic part of the lungs demonstrated changes in the expressions of the cell-cycle and inflammation related genes following UR and NMA treatment, respectively, in both the Tg and non-Tg mice. The gene expressions of epireguline, aurora kinase B, and cyclin B1 increased in the UR-treated Tg mice. We also found an increase in the plasma carcinoembryonic antigen level in the UR-treated Tg mice. Although UR treatment induced the formation of adenomas or adenocarcinomas in the lungs in all mice, earlier induction was apparent in the Tg mice. NMA treatment was found to induce the formation of adenomas and adenocarcinomas at week 26 in the Tg mice, but not in the non-Tg mice, and no expressions of specific genes were apparent in either genotype of mice. Our results indicate that analysis of cancer-related gene expressions in the lungs and plasma biomarkers at week 4 in rasH2 Tg mice could be a screening tool for carcinogenicity, especially of mutagenic carcinogens.

Bone Resorption Is Inhibited by an Osteocyte-Derived Protein

In the process of bone resorption, osteoclasts encounter a large number of osteocytes excavated from the bone tissue. For instance, osteocytes released from the collagen matrix have been shown to be engulfed into osteoclasts by phagocytosis. After the osteoclast-osteocyte encounter or incorporation of osteocytes into osteoclasts, it is possible that osteocytes transmit some signals to osteoclasts.