Publications by authors named "Hiroshi Kogo"

74 Publications

FABP7 Regulates Acetyl-CoA Metabolism Through the Interaction with ACLY in the Nucleus of Astrocytes.

Mol Neurobiol 2020 Dec 19;57(12):4891-4910. Epub 2020 Aug 19.

Department of Organ Anatomy, Tohoku University Graduate School of Medicine, Sendai, 980-8575, Japan.

Fatty acid binding protein 7 (FABP7) is an intracellular fatty acid chaperon that is highly expressed in astrocytes, oligodendrocyte-precursor cells, and malignant glioma. Previously, we reported that FABP7 regulates the response to extracellular stimuli by controlling the expression of caveolin-1, an important component of lipid raft. Here, we explored the detailed mechanisms underlying FABP7 regulation of caveolin-1 expression using primary cultured FABP7-KO astrocytes as a model of loss of function and NIH-3T3 cells as a model of gain of function. We discovered that FABP7 interacts with ATP-citrate lyase (ACLY) and is important for acetyl-CoA metabolism in the nucleus. This interaction leads to epigenetic regulation of several genes, including caveolin-1. Our novel findings suggest that FABP7-ACLY modulation of nuclear acetyl-CoA has more influence on histone acetylation than cytoplasmic acetyl-CoA. The changes to histone structure may modify caveolae-related cell activity in astrocytes and tumors, including malignant glioma.
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http://dx.doi.org/10.1007/s12035-020-02057-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7541391PMC
December 2020

Successful generation of epigenetic disease model mice by targeted demethylation of the epigenome.

Genome Biol 2020 04 1;21(1):77. Epub 2020 Apr 1.

Laboratory of Genome Science, Biosignal Genome Resource Center, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi, Gunma, 371-8512, Japan.

Background: Epigenetic modifications, including DNA methylation, play an important role in gene silencing and genome stability. Consequently, epigenetic dysregulation can cause several diseases, such as cancer, obesity, diabetes, autism, and imprinting disorders.

Results: We validate three methods for the generation of epigenome-edited mice using the dCas9-SunTag and single-chain variable fragment-TET1 catalytic domain. We generate model mice for Silver-Russell syndrome (SRS), an imprinting disorder, by target-specific DNA demethylation in the H19 differentially methylated region. Like SRS patients, these mice show H19 upregulation and Igf2 downregulation, leading to severe intrauterine and postnatal growth retardation.

Conclusion: This is the first report of an imprinting disease model animal generated by targeted demethylation of specific loci of the epigenome in fertilized eggs. Epigenome-edited animals are also useful for exploring the causative epimutations in epigenetic diseases.
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http://dx.doi.org/10.1186/s13059-020-01991-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7110793PMC
April 2020

Long-term Pilocarpine Treatment Improves Salivary Flow in Irradiated Mice.

Acta Histochem Cytochem 2019 Jun 19;52(3):45-58. Epub 2019 Jun 19.

Department of Anatomy and Cell Biology, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.

Radiation therapy for head and neck cancer frequently causes salivary gland dysfunction. Pilocarpine is a clinically approved and effective drug that induces saliva secretion, thereby keeping the oral mucosa moist and reducing discomfort in patients, but the effect is transient. We expected that this drug also has beneficial long-term effects that maintain the integrity of salivary glands by reducing, for instance, apoptosis. Here, we examined the effects of long-term pilocarpine administration in irradiated mice. The results indicated that long-term pilocarpine administration significantly improved salivary flow in irradiated mice, suggesting the potential beneficial effects of long-term administration. To elucidate the underlying mechanism, we analyzed the histology, apoptosis, and proliferation of acinar cells, and the expression of functional membrane proteins such as transmembrane member 16A, aquaporin-5, and Na-K-Cl cotransporter. Long-term pilocarpine treatment seemed to decrease irradiation-induced apoptosis, although the change was not statistically significant. The present results indicated that long-term administration of pilocarpine has beneficial effects on salivary flow in irradiated mice, and suggested that long-term administration possibly decreases apoptosis in irradiated salivary glands.
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http://dx.doi.org/10.1267/ahc.19006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6643095PMC
June 2019

The DNA Damage Checkpoint Eliminates Mouse Oocytes with Chromosome Synapsis Failure.

Mol Cell 2017 Sep 24;67(6):1026-1036.e2. Epub 2017 Aug 24.

Cornell University, Departments of Biomedical Sciences and Molecular Biology and Genetics, Ithaca, NY 14850, USA. Electronic address:

Pairing and synapsis of homologous chromosomes during meiosis is crucial for producing genetically normal gametes and is dependent upon repair of SPO11-induced double-strand breaks (DSBs) by homologous recombination. To prevent transmission of genetic defects, diverse organisms have evolved mechanisms to eliminate meiocytes containing unrepaired DSBs or unsynapsed chromosomes. Here we show that the CHK2 (CHEK2)-dependent DNA damage checkpoint culls not only recombination-defective mouse oocytes but also SPO11-deficient oocytes that are severely defective in homolog synapsis. The checkpoint is triggered in oocytes that accumulate a threshold level of spontaneous DSBs (∼10) in late prophase I, the repair of which is inhibited by the presence of HORMAD1/2 on unsynapsed chromosome axes. Furthermore, Hormad2 deletion rescued the fertility of oocytes containing a synapsis-proficient, DSB repair-defective mutation in a gene (Trip13) required for removal of HORMADs from synapsed chromosomes, suggesting that many meiotic DSBs are normally repaired by intersister recombination in mice.
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http://dx.doi.org/10.1016/j.molcel.2017.07.027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5621520PMC
September 2017

A positive feedback loop between progesterone and microsomal prostaglandin E synthase-1-mediated PGE2 promotes production of both in mouse granulosa cells.

Prostaglandins Other Lipid Mediat 2016 03 10;123:56-62. Epub 2016 May 10.

Department of Endocrine and Neural Pharmacology, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.

Microsomal prostaglandin E synthase-1 (mPGES-1) is primarily expressed in granulosa cells (GCs) in the preovulatory follicle. Both prostaglandin E2 (PGE2) and progesterone (P4) are implicated in various reproductive functions. Here, we demonstrate that mPges-1 may be a direct downstream target gene of the P4 receptor and P4-stimulated PGE2 secretion can stimulate P4 production in a newly generated mouse GC line (GtsT). Treatment of GtsT cells with a P4 receptor agonist, norgestrel, markedly increased mPGES-1 expression detected by RT-PCR analysis. PGE2 secretion measured by an enzyme-linked immunosorbent assay was enhanced by P4 treatment. Luciferase assays revealed that the proximal promoter region of the mPges-1 gene was responsible for the effects of P4 treatment. Conversely, PGE2 treatment stimulated P4 secretion, which coordinated with mRNA expression of steroidogenic acute regulatory protein. Taken together, P4 may regulate mPGES-1 expression to increase PGE2 secretion and in turn P4 production. An autocrine loop between P4 and PGE2 might function to maintain the increased levels of both in GCs.
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http://dx.doi.org/10.1016/j.prostaglandins.2016.05.002DOI Listing
March 2016

Requirement of DLG1 for cardiovascular development and tissue elongation during cochlear, enteric, and skeletal development: possible role in convergent extension.

PLoS One 2015 10;10(4):e0123965. Epub 2015 Apr 10.

Department of Anatomy and Cell Biology, Gunma University Graduate School of Medicine, Gunma, Japan.

The Dlg1 gene encodes a member of the MAGUK protein family involved in the polarization of epithelial cells. Null mutant mice for the Dlg1 gene (Dlg1-/- mice) exhibit respiratory failure and cyanosis, and die soon after birth. However, the cause of this neonatal lethality has not been determined. In the present study, we further examined Dlg1-/- mice and found severe defects in the cardiovascular system, including ventricular septal defect, persistent truncus arteriosus, and double outlet right ventricle, which would cause the neonatal lethality. These cardiovascular phenotypes resemble those of mutant mice lacking planar cell polarity (PCP) genes and support a recent notion that DLG1 is involved in the PCP pathway. We assessed the degree of involvement of DLG1 in the development of other organs, as the cochlea, intestine, and skeleton, in which PCP signaling has been suggested to play a role. In the organ of Corti, tissue elongation was inhibited accompanied by disorganized arrangement of the hair cell rows, while the orientation of the stereocilia bundle was normal. In the sternum, cleft sternum, abnormal calcification pattern of cartilage, and disorganization of chondrocytes were observed. Furthermore, shortening of the intestine, sternum, and long bones of the limbs was observed. These phenotypes of Dlg1-/- mice involving cellular disorganization and insufficient tissue elongation strongly suggest a defect in the convergent extension movements in these mice. Thus, our present results provide a possibility that DLG1 is particularly required for convergent extension among PCP signaling-dependent processes.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0123965PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4393223PMC
April 2016

Fatty acid-binding protein 7 regulates function of caveolae in astrocytes through expression of caveolin-1.

Glia 2015 May 19;63(5):780-94. Epub 2015 Jan 19.

Department of Organ Anatomy, Yamaguchi University Graduate School of Medicine, Ube, Japan.

Fatty acid-binding proteins (FABPs) bind and solubilize long-chain fatty acids, controlling intracellular lipid dynamics. FABP7 is expressed by astrocytes in the developing brain, and suggested to be involved in the control of astrocyte lipid homeostasis. In this study, we sought to examine the role of FABP7 in astrocytes, focusing on plasma membrane lipid raft function, which is important for receptor-mediated signal transduction in response to extracellular stimuli. In FABP7-knockout (KO) astrocytes, the ligand-dependent accumulation of Toll-like receptor 4 (TLR4) and glial cell-line-derived neurotrophic factor receptor alpha 1 into lipid raft was decreased, and the activation of mitogen-activated protein kinases and nuclear factor-κB was impaired after lipopolysaccharide (LPS) stimulation when compared with wild-type astrocytes. In addition, the expression of caveolin-1, not cavin-1, 2, 3, caveolin-2, and flotillin-1, was found to be decreased at the protein and transcriptional levels. FABP7 re-expression in FABP7-KO astrocytes rescued the decreased level of caveolin-1. Furthermore, caveolin-1-transfection into FABP7-KO astrocytes significantly increased TLR4 recruitment into lipid raft and tumor necrosis factor-α production after LPS stimulation. Taken together, these data suggest that FABP7 controls lipid raft function through the regulation of caveolin-1 expression and is involved in the response of astrocytes to the external stimuli. GLIA 2015;63:780-794.
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http://dx.doi.org/10.1002/glia.22784DOI Listing
May 2015

Age-related decrease of meiotic cohesins in human oocytes.

PLoS One 2014 7;9(5):e96710. Epub 2014 May 7.

Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi, Japan.

Aneuploidy in fetal chromosomes is one of the causes of pregnancy loss and of congenital birth defects. It is known that the frequency of oocyte aneuploidy increases with the human maternal age. Recent data have highlighted the contribution of cohesin complexes in the correct segregation of meiotic chromosomes. In mammalian oocytes, cohesion is established during the fetal stages and meiosis-specific cohesin subunits are not replenished after birth, raising the possibility that the long meiotic arrest of oocytes facilitates a deterioration of cohesion that leads to age-related increases in aneuploidy. We here examined the cohesin levels in dictyate oocytes from different age groups of humans and mice by immunofluorescence analyses of ovarian sections. The meiosis-specific cohesin subunits, REC8 and SMC1B, were found to be decreased in women aged 40 and over compared with those aged around 20 years (P<0.01). Age-related decreases in meiotic cohesins were also evident in mice. Interestingly, SMC1A, the mitotic counterpart of SMC1B, was substantially detectable in human oocytes, but little expressed in mice. Further, the amount of mitotic cohesins of mice slightly increased with age. These results suggest that, mitotic and meiotic cohesins may operate in a coordinated way to maintain cohesions over a sustained period in humans and that age-related decreases in meiotic cohesin subunits impair sister chromatid cohesion leading to increased segregation errors.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0096710PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4013030PMC
October 2015

Effects of repeated administration of pilocarpine and isoproterenol on aquaporin-5 expression in rat salivary glands.

Acta Histochem Cytochem 2013 Dec 25;46(6):187-97. Epub 2013 Dec 25.

Department of Anatomy and Cell Biology, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.

Aquaporins are water channel proteins which enable rapid water movement across the plasma membrane. Aquaporin-5 (AQP5) is the major aquaporin and is expressed on the apical membrane of salivary gland acinar cells. We examined the effects of repeated administration of pilocarpine, a clinically useful stimulant for salivary fluid secretion, and isoproterenol (IPR), a stimulant for salivary protein secretion, on the abundance of AQP5 protein in rat salivary glands by immunofluorescence microscopy and semi-quantitative immunoblotting. Unexpectedly AQP5 was decreased in pilocarpine-administered salivary glands, in which fluid secretion must be highly stimulated, implying that AQP5 might not be required for fluid secretion at least in pilocarpine-administered state. The abundance of AQP5, on the other hand, was found to be significantly increased in IPR-administered submandibular and parotid glands. To address the possible mechanism of the elevation of AQP5 abundance in IPR-administered animals, changes of AQP5 level in fasting animals, in which the exocytotic events are reduced, were examined. AQP5 was found to be decreased in fasting animals as expected. These results suggested that the elevation of cAMP and/or frequent exocytotic events could increase AQP5 protein. AQP5 expression seems to be easily changed by salivary stimulants, although these changes do not always reflect the ability in salivary fluid secretion.
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http://dx.doi.org/10.1267/ahc.13037DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3929617PMC
December 2013

Two sequential cleavage reactions on cruciform DNA structures cause palindrome-mediated chromosomal translocations.

Nat Commun 2013 ;4:1592

Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan.

Gross chromosomal rearrangements (GCRs), such as translocations, deletions or inversions, are often generated by illegitimate repair between two DNA breakages at regions with nucleotide sequences that might potentially adopt a non-B DNA conformation. We previously established a plasmid-based model system that recapitulates palindrome-mediated recurrent chromosomal translocations in humans, and demonstrated that cruciform DNA conformation is required for the translocation-like rearrangements. Here we show that two sequential reactions that cleave the cruciform structures give rise to the translocation: GEN1-mediated resolution that cleaves diagonally at the four-way junction of the cruciform and Artemis-mediated opening of the subsequently formed hairpin ends. Indeed, translocation products in human sperm reveal the remnants of this two-step mechanism. These two intrinsic pathways that normally fulfil vital functions independently, Holliday-junction resolution in homologous recombination and coding joint formation in rearrangement of antigen-receptor genes, act upon the unusual DNA conformation in concert and lead to a subset of recurrent GCRs in humans.
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http://dx.doi.org/10.1038/ncomms2595DOI Listing
June 2013

HORMAD2 is essential for synapsis surveillance during meiotic prophase via the recruitment of ATR activity.

Genes Cells 2012 Nov 8;17(11):897-912. Epub 2012 Oct 8.

Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi, 470-1192, Japan.

Meiotic chromosome segregation requires homologous pairing, synapsis and crossover recombination during meiotic prophase. The checkpoint kinase ATR has been proposed to be involved in the quality surveillance of these processes, although the underlying mechanisms remain largely unknown. In our present study, we generated mice lacking HORMAD2, a protein that localizes to unsynapsed meiotic chromosomes. We show that this Hormad2 deficiency hampers the proper recruitment of ATR activity to unsynapsed chromosomes. Male Hormad2-deficient mice are infertile due to spermatocyte loss as a result of characteristic impairment of sex body formation; an ATR- and γH2AX-enriched repressive chromatin domain is formed, but is partially dissociated from the elongated sex chromosome axes. In contrast to males, Hormad2-deficient females are fertile. However, our analysis of Hormad2/Spo11 double-mutant females shows that the oocyte number is negatively correlated with the frequency of pseudo-sex body formation in a Hormad2 gene dosage-dependent manner. This result suggests that the elimination of Spo11-deficient asynaptic oocytes is associated with the HORMAD2-dependent pseudo-sex body formation that is likely initiated by local concentration of ATR activity in the absence of double-strand breaks. Our results thus show a HORMAD2-dependent quality control mechanism that recognizes unsynapsis and recruits ATR activity during mammalian meiosis.
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http://dx.doi.org/10.1111/gtc.12005DOI Listing
November 2012

Failure of homologous synapsis and sex-specific reproduction problems.

Front Genet 2012 18;3:112. Epub 2012 Jun 18.

Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi, Japan.

The prophase of meiosis I ensures the correct segregation of chromosomes to each daughter cell. This includes the pairing, synapsis, and recombination of homologous chromosomes. A subset of chromosomal abnormalities, including translocation and inversion, disturbs these processes, resulting in the failure to complete synapsis. This activates the meiotic pachytene checkpoint, and the gametes are fated to undergo cell cycle arrest and subsequent apoptosis. Spermatogenic cells appear to be more vulnerable to the pachytene checkpoint, and male carriers of chromosomal abnormalities are more susceptible to infertility. In contrast, oocytes tend to bypass the checkpoint and instead generate other problems, such as chromosome imbalance that often leads to recurrent pregnancy loss in female carriers. Recent advances in genetic manipulation technologies have increased our knowledge about the pachytene checkpoint and surveillance systems that detect chromosomal synapsis. This review focuses on the consequences of synapsis failure in humans and provides an overview of the mechanisms involved. We also discuss the sexual dimorphism of the involved pathways that leads to the differences in reproductive outcomes between males and females.
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http://dx.doi.org/10.3389/fgene.2012.00112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3376420PMC
October 2012

Screening of genes involved in chromosome segregation during meiosis I: in vitro gene transfer to mouse fetal oocytes.

J Hum Genet 2012 Aug 31;57(8):515-22. Epub 2012 May 31.

Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Aichi, Japan.

The events that take place during the prophase of meiosis I are essential for the correct segregation of homologous chromosomes. Defects in these processes likely contribute to infertility or recurrent pregnancy loss in humans. To screen for candidate genes for reproductive failure due to meiotic defects, we have analyzed the gene expression patterns in fetal, neonatal and adult gonads of both male and female mice by microarray and thereby identified 241 genes that are expressed specifically during prophase of meiosis I. Combined with our previous data obtained from developing spermatocytes, a total of 99 genes were identified that are upregulated in early prophase I. We confirmed the meiotic prophase I-specific expression of these genes using qRT-PCR. To further screen this panel for candidate genes that fulfill important roles in homologous pairing, synapsis and recombination, we established a gene transfer system for prophase I oocytes in combination with in vitro organ culture of ovaries, and successfully determined the localization of the selected genes. This gene set can thus serve as a resource for targeted sequence analysis via next-generation sequencing to identify the genes associated with human reproduction failure due to meiotic defects.
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http://dx.doi.org/10.1038/jhg.2012.61DOI Listing
August 2012

HORMAD1-dependent checkpoint/surveillance mechanism eliminates asynaptic oocytes.

Genes Cells 2012 Jun 25;17(6):439-54. Epub 2012 Apr 25.

Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan.

Meiotic pachytene checkpoints monitor the failure of homologous recombination and synapsis to ensure faithful chromosome segregation during gamete formation. To date, the molecular basis of the mammalian pachytene checkpoints has remained largely unknown. We here report that mouse HORMAD1 is required for a meiotic prophase checkpoint that eliminates asynaptic oocytes. Hormad1-deficient mice are infertile and show an extensive failure of homologous pairing and synapsis, consistent with the evolutionarily conserved function of meiotic HORMA domain proteins. Unexpectedly, Hormad1-deficient ovaries contain a normal number of oocytes despite asynapsis and consequently produce aneuploid oocytes, indicating a checkpoint failure. By the analysis of Hormad1/Spo11 double mutants, the Hormad1 deficiency was found to abrogate the massive oocyte loss in the Spo11-deficient ovary. The Hormad1 deficiency also causes the eventual loss of pseudo sex body in the Spo11-deficient ovary and testis. These results suggest the involvement of HORMAD1 in the repressive chromatin domain formation that is proposed to be important in the meiotic prophase checkpoints. We also show the extensive phosphorylation of HORMAD1 in the Spo11-deficient testis and ovary, suggesting an involvement of novel DNA damage-independent phosphorylation signaling in the surveillance mechanism. Our present results provide clues to HORMAD1-dependent checkpoint in response to asynapsis in mammalian meiosis.
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http://dx.doi.org/10.1111/j.1365-2443.2012.01600.xDOI Listing
June 2012

Molecular basis of maternal age-related increase in oocyte aneuploidy.

Congenit Anom (Kyoto) 2012 Mar;52(1):8-15

Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University Department of Obstetrics and Gynecology, Fujita Health University School of Medicine, Toyoake, Aichi, Japan.

Aneuploidy is one of the most common and serious pregnancy complications in humans. Most conceptuses with autosomal aneuploidy die in utero, resulting in early pregnancy loss. However, some fetuses with aneuploidy survive to term but suffer from disorders associated with congenital anomalies and mental retardation, such as Down syndrome with trisomy 21. Three general characteristics of this condition are well acknowledged: (i) in most cases the extra chromosome is of maternal origin; (ii) most cases are derived from a malsegregation event in meiosis I; and (iii) the frequency of these errors increases with maternal age. The basis for the age-dependent increase in meiosis I errors has been a long-standing enigma. Many investigators have addressed the nature of this biological phenomenon through genomic analyses of extra chromosome 21 using polymorphic markers to determine the frequency or location of crossovers that should ensure faithful chromosome segregation. Cytogenetic analyses of in vitro unfertilized oocytes have also been performed. However, no definitive conclusions regarding meiosis I errors have yet been reached from such studies. Recent findings in conditional knock-out mice for meiosis-specific cohesin have shed further light on this issue. The present review focuses on the current understanding of age-related aneuploidy and provides an overview of the mechanisms involved. We refer to recent data to illustrate some of the new paradigms that have arisen in this field.
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http://dx.doi.org/10.1111/j.1741-4520.2011.00350.xDOI Listing
March 2012

Mechanism of complex gross chromosomal rearrangements: a commentary on concomitant microduplications of MECP2 and ATRX in male patients with severe mental retardation.

J Hum Genet 2012 Feb 15;57(2):81-3. Epub 2011 Dec 15.

The Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan.

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http://dx.doi.org/10.1038/jhg.2011.143DOI Listing
February 2012

DNA secondary structure is influenced by genetic variation and alters susceptibility to de novo translocation.

Mol Cytogenet 2011 Sep 8;4:18. Epub 2011 Sep 8.

Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan.

Background: Cumulative evidence suggests that DNA secondary structures impact DNA replication, transcription and genomic rearrangements. One of the best studied examples is the recurrent constitutional t(11;22) in humans that is mediated by potentially cruciform-forming sequences at the breakpoints, palindromic AT-rich repeats (PATRRs). We previously demonstrated that polymorphisms of PATRR sequences affect the frequency of de novo t(11;22)s in sperm samples from normal healthy males. These studies were designed to determine whether PATRR polymorphisms affect DNA secondary structure, thus leading to variation in translocation frequency.

Methods: We studied the potential for DNA cruciform formation for several PATRR11 polymorphic alleles using mobility shift analysis in gel electrophoresis as well as by direct visualization of the DNA by atomic force microscopy. The structural data for various alleles were compared with the frequency of de novo t(11;22)s the allele produced.

Results: The data indicate that the propensity for DNA cruciform structure of each polymorphic allele correlates with the frequency of de novo t(11;22)s produced (r = 0.77, P = 0.01).

Conclusions: Although indirect, our results strongly suggest that the PATRR adopts unstable cruciform structures during spermatogenesis that act as translocation hotspots in humans.
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http://dx.doi.org/10.1186/1755-8166-4-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3197554PMC
September 2011

Characterization of a novel mouse gene encoding an SYCP3-like protein that relocalizes from the XY body to the nucleolus during prophase of male meiosis I.

Biol Reprod 2011 Jul 30;85(1):165-71. Epub 2011 Mar 30.

Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Japan.

Xlr6 is a novel but uncharacterized X-linked gene that is upregulated in meiotic prophase I during mouse spermatogenesis. Xlr6 belongs to the Xlr gene family, which includes a component of the axial/lateral element of the synaptonemal complex, Sycp3, and its transcripts are abundant in the fetal ovary and adult testis. Immunostaining and Western blot analysis demonstrate a diffuse localization pattern for this protein in the nucleus and an association with chromatin during the leptotene and zygotene stages. In males, XLR6 accumulates at the XY body of early pachytene to midpachytene spermatocytes, although the Xlr6 gene is subjected to meiotic sex chromosome inactivation. During the late pachytene and diplotene stages, the XLR6 protein relocalizes from the XY body to the nucleolus and, eventually, disappears by diakinesis. In females, XLR6 disappears at the pachytene stage, whereas it accumulates at the unpaired chromosomes occasionally observed in wild-type female mice. Although the amino acid sequence of XLR6 has a high similarity with SYCP3, its distinct localization pattern and dynamism suggest a unique chromatin modification function that leads to the transcriptional repression of ribosomal DNA in addition to sex chromosome genes.
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http://dx.doi.org/10.1095/biolreprod.110.087270DOI Listing
July 2011

Polymorphisms of the 22q11.2 breakpoint region influence the frequency of de novo constitutional t(11;22)s in sperm.

Hum Mol Genet 2010 Jul 13;19(13):2630-7. Epub 2010 Apr 13.

Institute for Comprehensive Medical Science, Fujita Health University, Aichi, Japan.

The constitutional t(11;22) is the most frequent recurrent non-Robertsonian translocation in humans, the breakpoints of which are located within palindromic AT-rich repeats on 11q23 and 22q11 (PATRR11 and PATRR22). Genetic variation of the PATRR11 was found to affect de novo t(11;22) translocation frequency in sperm derived from normal healthy males, suggesting the hypothesis that polymorphisms of the PATRR22 might also influence the translocation frequency. Although the complicated structure of the PATRR22 locus prevented determining the genotype of the PATRR22 in each individual, genotyping of flanking markers as well as identification of rare variants allowed us to demonstrate an association between the PATRR22 allele type and the translocation frequency. We found that size and symmetry of the PATRR22 affect the de novo translocation frequency, which is lower for the shorter or more asymmetric versions. These data lend support to our hypothesis that the PATRRs form secondary structures in the nucleus that induce genomic instability leading to the recurrent translocation.
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http://dx.doi.org/10.1093/hmg/ddq150DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2883341PMC
July 2010

Screening of genes involved in chromosome segregation during meiosis I: toward the identification of genes responsible for infertility in humans.

J Hum Genet 2010 May 26;55(5):293-9. Epub 2010 Mar 26.

Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi, Japan.

Prophase I of male meiosis during early spermatogenesis involves dynamic chromosome segregation processes, including synapsis, meiotic recombination and cohesion. Genetic defects in the genes that participate in these processes consistently cause reproduction failure in mice. To identify candidate genes responsible for infertility in humans, we performed gene expression profiling of mouse spermatogenic cells undergoing meiotic prophase I. Cell fractions enriched in spermatogonia, leptotene/zygotene spermatocytes or pachytene spermatocytes from developing mouse testis were separately isolated by density gradient sedimentation and subjected to microarray analysis. A total of 726 genes were identified that were upregulated in leptotene/zygotene spermatocytes. To evaluate the screening efficiency for meiosis-specific genes, we randomly selected 12 genes from this gene set and characterized each gene product using reverse transcription (RT)-PCR of RNA from gonadal tissues, in situ hybridization on testicular tissue sections and subcellular localization analysis of the encoded protein. Four of the 12 genes were confirmed as genes expressed in meiotic stage and 2 of these 4 genes were novel, previously uncharacterized genes. Among the three confirmation methods that were used, RT-PCR appeared to be the most efficient method for further screening. These 726 candidates for human infertility genes might serve as a useful resource for next-generation sequencing combined with exon capture by microarray.
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http://dx.doi.org/10.1038/jhg.2010.26DOI Listing
May 2010

Paternal origin of the de novo constitutional t(11;22)(q23;q11).

Eur J Hum Genet 2010 Jul 24;18(7):783-7. Epub 2010 Feb 24.

Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi, Japan.

The constitutional t(11;22)(q23;q11) is a well-known recurrent non-Robertsonian translocation in humans. Although translocations generally occur in a random fashion, the break points of t(11;22)s are concentrated within several hundred base pairs on 11q23 and 22q11. These regions are characterized by palindromic AT-rich repeats (PATRRs), which appear to be responsible for the genomic instability. Translocation-specific PCR detects de novo t(11;22)s in sperm from healthy males at a frequency of 1/10(4)-10(5), but never in lymphoblasts, fibroblasts or other human somatic cell lines. This suggests that the generation of t(11;22) rearrangement is linked to gametogenesis, although female germ cells have not been tested. Here, we have studied eight cases of de novo t(11;22) to determine the parental origin of the translocation using the polymorphisms on the relevant PATRRs. All of the eight translocations were found to be of paternal origin. This result implicates a possible novel mechanism of sperm-specific generation of palindrome-mediated chromosomal translocations.
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http://dx.doi.org/10.1038/ejhg.2010.20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2987363PMC
July 2010

[Multiple protrusions on the colonic surface associated with hypoproteinemia].

Nihon Shokakibyo Gakkai Zasshi 2009 Jul;106(7):1086-7, 1089

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July 2009

Impaired DNA replication prompts deletions within palindromic sequences, but does not induce translocations in human cells.

Hum Mol Genet 2009 Sep 11;18(18):3397-406. Epub 2009 Jun 11.

Division of Molecular Genetics, Fujita Health University, Toyoake, Aichi, Japan.

Palindromic regions are unstable and susceptible to deletion in prokaryotes and eukaryotes possibly due to stalled or slow replication. In the human genome, they also appear to become partially or completely deleted, while two palindromic AT-rich repeats (PATRR) contribute to known recurrent constitutional translocations. To explore the mechanism that causes the development of palindrome instabilities in humans, we compared the incidence of de novo translocations and deletions at PATRRs in human cells. Using a highly sensitive PCR assay that can detect single molecules, de novo deletions were detected neither in human somatic cells nor in sperm. However, deletions were detected at low frequency in cultured cell lines. Inhibition of DNA replication by administration of siRNA against the DNA polymerase alpha 1 (POLA1) gene or introduction of POLA inhibitors increased the frequency. This is in contrast to PATRR-mediated translocations that were never detected in similar conditions but were observed frequently in human sperm samples. Further deletions were found to take place during both leading- and lagging-strand synthesis. Our data suggest that stalled or slow replication induces deletions within PATRRs, but that other mechanisms might contribute to PATRR-mediated recurrent translocations in humans.
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http://dx.doi.org/10.1093/hmg/ddp279DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2729664PMC
September 2009

Preoperative plasma adiponectin level is a risk factor for postoperative infection following colorectal cancer surgery.

J Surg Res 2009 Dec 9;157(2):227-34. Epub 2008 Oct 9.

Department of Surgery, Nippon Medical School Tama-Nagayama Hospital, Tama, Tokyo, Japan.

Background: Adiponectin is produced exclusively by adipose tissues. It is associated with visceral adiposity and various metabolic disorders, and acts as an anti-inflammatory protein that inhibits nuclear factor-kappaB activation. The purpose of this study is to clarify the association between the preoperative plasma adiponectin levels and the development of postoperative infection following colorectal cancer surgery.

Methods: Peripheral blood samples were collected from 41 colorectal cancer patients before surgery and on postoperative days (PODs) 1, 3, 5, and 7. Plasma adiponectin, leptin, and serum C-reactive protein (CRP) levels were measured and the white blood cells (WBCs) were counted. Subcutaneous and visceral fat volumes were quantified by preoperative CT scans. The patients were divided into a group with postoperative infections and an uninfected group.

Results: In both groups, the postoperative plasma adiponectin levels decreased transiently and then gradually recovered. However, the infected group had significantly lower adiponectin levels throughout the perioperative period than the uninfected group. Logistic regression analysis revealed that preoperative adiponectin level was an independent risk factor for postoperative infection.

Conclusions: Preoperative adiponectin levels may be useful for anticipating the development of postoperative infection following colorectal cancer surgery.
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http://dx.doi.org/10.1016/j.jss.2008.09.007DOI Listing
December 2009

Recent advance in our understanding of the molecular nature of chromosomal abnormalities.

J Hum Genet 2009 May 17;54(5):253-60. Epub 2009 Apr 17.

Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi, Japan.

The completion of the human genome project has enabled researchers to characterize the breakpoints for various chromosomal structural abnormalities including deletions, duplications or translocations. This in turn has shed new light on the molecular mechanisms underlying the onset of gross chromosomal rearrangements. On the other hand, advances in genetic manipulation technologies for various model organisms has increased our knowledge of meiotic chromosome segregation, errors which, contribute to chromosomal aneuploidy. This review focuses on the current understanding of germ line chromosomal abnormalities and provides an overview of the mechanisms involved. We refer to our own recent data and those of others to illustrate some of the new paradigms that have arisen in this field. We also discuss some perspectives on the sexual dimorphism of some of the pathways that leads to these chromosomal abnormalities.
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http://dx.doi.org/10.1038/jhg.2009.35DOI Listing
May 2009

Mutations of the SYCP3 gene in women with recurrent pregnancy loss.

Am J Hum Genet 2009 Jan 24;84(1):14-20. Epub 2008 Dec 24.

Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan.

Aneuploidy, a chromosomal numerical abnormality in the conceptus or fetus, occurs in at least 5% of all pregnancies and is the leading cause of early pregnancy loss in humans. Accumulating evidence now suggests that the correct segregation of chromosomes is affected by events occurring in prophase during meiosis I. These events include homologous chromosome pairing, sister-chromatid cohesion, and meiotic recombination. In our current study, we show that mutations in SYCP3, a gene encoding an essential component of the synaptonemal complex that is central to the interaction of homologous chromosomes, are associated with recurrent pregnancy loss. Two out of 26 women with recurrent pregnancy loss of unknown cause were found to carry independent heterozygous nucleotide alterations in this gene, neither of which was present among a group of 150 fertile women. Analysis of transcripts from minigenes harboring each of these two mutations revealed that both affected normal splicing, possibly resulting in the production of C-terminally mutated proteins. The mutant proteins were found to interact with their wild-type counterpart in vitro and inhibit the normal fiber formation of the SYCP3 protein when coexpressed in a heterologous system. These data suggest that these mutations are likely to generate an aberrant synaptonemal complex in a dominant-negative manner and contribute to abnormal chromosomal behavior that might lead to recurrent miscarriage. Combined with the fact that similar mutations have been previously identified in two males with azoospermia, our current data suggest that sexual dimorphism in response to meiotic disruption occurs even in humans.
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http://dx.doi.org/10.1016/j.ajhg.2008.12.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2668043PMC
January 2009

Chromosomal instability mediated by non-B DNA: cruciform conformation and not DNA sequence is responsible for recurrent translocation in humans.

Genome Res 2009 Feb 7;19(2):191-8. Epub 2008 Nov 7.

Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan.

Chromosomal aberrations have been thought to be random events. However, recent findings introduce a new paradigm in which certain DNA segments have the potential to adopt unusual conformations that lead to genomic instability and nonrandom chromosomal rearrangement. One of the best-studied examples is the palindromic AT-rich repeat (PATRR), which induces recurrent constitutional translocations in humans. Here, we established a plasmid-based model that promotes frequent intermolecular rearrangements between two PATRRs in HEK293 cells. In this model system, the proportion of PATRR plasmid that extrudes a cruciform structure correlates to the levels of rearrangement. Our data suggest that PATRR-mediated translocations are attributable to unusual DNA conformations that confer a common pathway for chromosomal rearrangements in humans.
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http://dx.doi.org/10.1101/gr.079244.108DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2652202PMC
February 2009

Increased levels of pregnancy-associated plasma protein-A2 in the serum of pre-eclamptic patients.

Mol Hum Reprod 2008 Oct 18;14(10):595-602. Epub 2008 Sep 18.

Department of Obstetrics and Gynecology, Fujita Health University School of Medicine, 1-98 Dengakugakubo, Kutsukake, Toyoake, Aichi 470-1192, Japan.

Pregnancy-associated plasma protein-A and -A2 (PAPP-A and -A2) are proteases that cleave insulin-like growth factor-binding proteins (IGFBPs), resulting in local activation of IGF signaling pathways. Here, we examined PAPP-A and -A2 mRNA and protein levels in placenta and maternal sera from women with pre-eclampsia and compared them with samples from uncomplicated pregnancy. PAPP-A2 but not PAPP-A mRNA and protein were elevated in pre-eclamptic placenta (P < 0.01). PAPP-A2 is normally produced in placental syncytiotrophoblast cells and maternal decidua. PAPP-A2 in syncytiotrophoblast cells was dramatically increased in pre-eclampsia. Maternal serum concentrations of PAPP-A2 but not PAPP-A were also significantly elevated in pre-eclampsia as compared with uncomplicated pregnancy. mRNA levels of IGFBP5, a specific substrate for PAPP-A2 protease activity, were also significantly increased, suggesting a potential role for IGFBP5 in fetal and placental growth suppression during pre-eclampsia. However, IGFBP5 protein levels were not increased in placenta from pre-eclampsia, possibly due to cleavage by up-regulated PAPP-A2. These data might imply that PAPP-A2 may be up-regulated in pre-eclamptic pregnancy to compensate for IGFBP5-mediated suppression of the IGF pathway, although final birthweights are still low in pre-eclamptic pregnancy.
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http://dx.doi.org/10.1093/molehr/gan054DOI Listing
October 2008

[Role of implantation-related factors, stathmin and insulin-like growth factor-binding protein 7 in reproductive endocrinology].

Yakugaku Zasshi 2008 Apr;128(4):565-74

Department of Endocrine Pharmacology, Tokyo University of Pharmacy and Life Sciences, Hachioji City, Tokyo, Japan.

Successful implantation and placentation require that trophoblasts adhere to the uterine epithelium and penetrate the decidualized endometrium. However, the biochemical mechanisms of the establishment of pregnancy including these phenomena have not yet to be definitively elucidated. We have found that stathmin, a cytosolic phosphoprotein that regulates microtubule dynamics, and insulin-like growth factor-binding protein (IGFBP)-related protein 1 (IGFBP-rP1, now called IGF-binding protein 7) were highly expressed in the endometrium around the time of implantation and decidualization. In this article, we review our recent findings of the research regarding the functions of these implantation-associated proteins in endocrine physiology and pharmacology. Analysis of the expression of both factors in rodent and human uterus has revealed that both factors are crucial for the process of endometrial stromal cell differentiation.
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http://dx.doi.org/10.1248/yakushi.128.565DOI Listing
April 2008

Two different forms of palindrome resolution in the human genome: deletion or translocation.

Hum Mol Genet 2008 Apr 9;17(8):1184-91. Epub 2008 Jan 9.

Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan

Regions containing palindromic sequence are known to be susceptible to genomic rearrangement in prokaryotes and eukaryotes. Palindromic AT-rich repeats (PATRR) are hypervariable in the human genome, manifesting size polymorphisms and a propensity to rearrange. Size variations are mainly the result of internal deletions, while two PATRRs on 11q23 and 22q11 (PATRR11 and 22) contribute to generation of the t(11;22), a recurrent constitutional translocation. In this study, we analyzed the PATRR11 sequence of numerous polymorphic alleles in detail. Various types of shorter variants are likely derived from the most frequent approximately 450 bp PATRR11 by deletion. Deletion variants possess a significant number of identical nucleotides at their two endpoints, indicating the possible involvement of direct repeats within the PATRR11. Rare variants with insertional alterations involve AT-rich sequences of unknown origin. This is in contrast to palindrome-mediated translocations between PATRRs that manifest smaller deletions and only a limited number of identical nucleotides at the breakpoints. Further, we identified a rare translocation product that has a non-AT-rich insertion of a transcribed gene segment at the translocation breakpoint. Our data suggest that the outcomes of palindrome-mediated re-arrangements reflect distinct molecular pathways; intra-palindrome re-arrangements are possibly dictated by a replication slippage or microhomology-directed repair pathway, and inter-palindrome translocations are likely driven by non-homologous end joining.
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http://dx.doi.org/10.1093/hmg/ddn008DOI Listing
April 2008
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