Honors & Awards

  • Research Scholarship (Title: Elucidating fundamental regulators of male meiosis), the American Urological Association and the Urology Care Foundation (2016-2018)
  • Travel Grant Award for Early Career Researchers in Overseas, 2015 Annual Meeting of the Japanese Biochemical Society & Molecular Biology Society of Japan (2015)
  • Postdoctoral Fellowship (Controlling mechanism of sex-linked genes required for sperm function), the Lalor Foundation (2012-2014)
  • Academic Award for Superior Publication, 56th Japan Society for Reproductive Medicine (2011)
  • Academic Award for Graduate Students, 29th The Japanese Society of Andrology (2010)
  • Monbukagakusho Scholarship, Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) (2006-2010)

All Publications

  • SCML2 Establishes the Male Germline Epigenome through Regulation of Histone H2A Ubiquitination DEVELOPMENTAL CELL Hasegawa, K., Sin, H., Maezawa, S., Broering, T. J., Kartashov, A. V., Alavattam, K. G., Ichijima, Y., Zhang, F., Bacon, W. C., Greis, K. D., Andreassen, P. R., Barski, A., Namekawa, S. H. 2015; 32 (5): 574-588


    Gametogenesis is dependent on the expression of germline-specific genes. However, it remains unknown how the germline epigenome is distinctly established from that of somatic lineages. Here we show that genes commonly expressed in somatic lineages and spermatogenesis-progenitor cells undergo repression in a genome-wide manner in late stages of the male germline and identify underlying mechanisms. SCML2, a germline-specific subunit of a Polycomb repressive complex 1 (PRC1), establishes the unique epigenome of the male germline through two distinct antithetical mechanisms. SCML2 works with PRC1 and promotes RNF2-dependent ubiquitination of H2A, thereby marking somatic/progenitor genes on autosomes for repression. Paradoxically, SCML2 also prevents RNF2-dependent ubiquitination of H2A on sex chromosomes during meiosis, thereby enabling unique epigenetic programming of sex chromosomes for male reproduction. Our results reveal divergent mechanisms involving a shared regulator by which the male germline epigenome is distinguished from that of the soma and progenitor cells.

    View details for DOI 10.1016/j.devcel.2015.01.014

    View details for Web of Science ID 000350989300007

    View details for PubMedID 25703348

    View details for PubMedCentralID PMC4391279

  • Poised chromatin and bivalent domains facilitate the mitosis-to-meiosis transition in the male germline. BMC biology Sin, H., Kartashov, A. V., Hasegawa, K., Barski, A., Namekawa, S. H. 2015; 13: 53-?


    The male germline transcriptome changes dramatically during the mitosis-to-meiosis transition to activate late spermatogenesis genes and to transiently suppress genes commonly expressed in somatic lineages and spermatogenesis progenitor cells, termed somatic/progenitor genes.These changes reflect epigenetic regulation. Induction of late spermatogenesis genes during spermatogenesis is facilitated by poised chromatin established in the stem cell phases of spermatogonia, whereas silencing of somatic/progenitor genes during meiosis and postmeiosis is associated with formation of bivalent domains which also allows the recovery of the somatic/progenitor program after fertilization. Importantly, during spermatogenesis mechanisms of epigenetic regulation on sex chromosomes are different from autosomes: X-linked somatic/progenitor genes are suppressed by meiotic sex chromosome inactivation without deposition of H3K27me3.Our results suggest that bivalent H3K27me3 and H3K4me2/3 domains are not limited to developmental promoters (which maintain bivalent domains that are silent throughout the reproductive cycle), but also underlie reversible silencing of somatic/progenitor genes during the mitosis-to-meiosis transition in late spermatogenesis.

    View details for DOI 10.1186/s12915-015-0159-8

    View details for PubMedID 26198001

    View details for PubMedCentralID PMC4508805

  • The great escape Active genes on inactive sex chromosomes and their evolutionary implications EPIGENETICS Sin, H., Namekawa, S. H. 2013; 8 (9): 887-892


    Epigenetic mechanisms precisely regulate sex chromosome inactivation as well as genes that escape the silencing process. In male germ cells, DNA damage response factor RNF8 establishes active epigenetic modifications on the silent sex chromosomes during meiosis, and activates escape genes during a state of sex chromosome-wide silencing in postmeiotic spermatids. During the course of evolution, the gene content of escape genes in postmeiotic spermatids recently diverged on the sex chromosomes. This evolutionary feature mirrors the epigenetic processes of sex chromosomes in germ cells. In this article, we describe how epigenetic processes have helped to shape the evolution of sex chromosome-linked genes. Furthermore, we compare features of escape genes on sex chromosomes in male germ cells to escape genes located on the single X chromosome silenced during X-inactivation in females, clarifying the distinct evolutionary implications between male and female escape genes.

    View details for DOI 10.4161/epi.25672

    View details for Web of Science ID 000327624600002

    View details for PubMedID 23880818

    View details for PubMedCentralID PMC3883765

  • RNF8 regulates active epigenetic modifications and escape gene activation from inactive sex chromosomes in post-meiotic spermatids GENES & DEVELOPMENT Sin, H., Barski, A., Zhang, F., Kartashov, A. V., Nussenzweig, A., Chen, J., Andreassen, P. R., Namekawa, S. H. 2012; 26 (24): 2737-2748


    Sex chromosomes are uniquely subject to chromosome-wide silencing during male meiosis, and silencing persists into post-meiotic spermatids. Against this background, a select set of sex chromosome-linked genes escapes silencing and is activated in post-meiotic spermatids. Here, we identify a novel mechanism that regulates escape gene activation in an environment of chromosome-wide silencing in murine germ cells. We show that RNF8-dependent ubiquitination of histone H2A during meiosis establishes active epigenetic modifications, including dimethylation of H3K4 on the sex chromosomes. RNF8-dependent active epigenetic memory, defined by dimethylation of H3K4, persists throughout meiotic division. Various active epigenetic modifications are subsequently established on the sex chromosomes in post-meiotic spermatids. These RNF8-dependent modifications include trimethylation of H3K4, histone lysine crotonylation (Kcr), and incorporation of the histone variant H2AFZ. RNF8-dependent epigenetic programming regulates escape gene activation from inactive sex chromosomes in post-meiotic spermatids. Kcr accumulates at transcriptional start sites of sex-linked genes activated in an RNF8-dependent manner, and a chromatin conformational change is associated with RNF8-dependent epigenetic programming. Furthermore, we demonstrate that this RNF8-dependent pathway is distinct from that which recognizes DNA double-strand breaks. Our results establish a novel connection between a DNA damage response factor (RNF8) and epigenetic programming, specifically in establishing active epigenetic modifications and gene activation.

    View details for DOI 10.1101/gad.202713.112

    View details for Web of Science ID 000312775700008

    View details for PubMedID 23249736

    View details for PubMedCentralID PMC3533078

  • Human postmeiotic sex chromatin and its impact on sex chromosome evolution GENOME RESEARCH Sin, H., Ichijima, Y., Koh, E., Namiki, M., Namekawa, S. H. 2012; 22 (5): 827-836


    Sex chromosome inactivation is essential epigenetic programming in male germ cells. However, it remains largely unclear how epigenetic silencing of sex chromosomes impacts the evolution of the mammalian genome. Here we demonstrate that male sex chromosome inactivation is highly conserved between humans and mice and has an impact on the genetic evolution of human sex chromosomes. We show that, in humans, sex chromosome inactivation established during meiosis is maintained into spermatids with the silent compartment postmeiotic sex chromatin (PMSC). Human PMSC is illuminated with epigenetic modifications such as trimethylated lysine 9 of histone H3 and heterochromatin proteins CBX1 and CBX3, which implicate a conserved mechanism underlying the maintenance of sex chromosome inactivation in mammals. Furthermore, our analyses suggest that male sex chromosome inactivation has impacted multiple aspects of the evolutionary history of mammalian sex chromosomes: amplification of copy number, retrotranspositions, acquisition of de novo genes, and acquisition of different expression profiles. Most strikingly, profiles of escape genes from postmeiotic silencing diverge significantly between humans and mice. Escape genes exhibit higher rates of amino acid changes compared with non-escape genes, suggesting that they are beneficial for reproductive fitness and may allow mammals to cope with conserved postmeiotic silencing during the evolutionary past. Taken together, we propose that the epigenetic silencing mechanism impacts the genetic evolution of sex chromosomes and contributed to speciation and reproductive diversity in mammals.

    View details for DOI 10.1101/gr.135046.111

    View details for Web of Science ID 000303369600003

    View details for PubMedID 22375025

    View details for PubMedCentralID PMC3337429

  • Polycomb protein SCML2 facilitates H3K27me3 to establish bivalent domains in the male germline PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Maezawa, S., Hasegawa, K., Yukawa, M., Kubo, N., Sakashita, A., Alavattam, K. G., Sin, H., Kartashov, A. V., Sasaki, H., Barski, A., Namekawa, S. H. 2018; 115 (19): 4957–62


    Repressive H3K27me3 and active H3K4me2/3 together form bivalent chromatin domains, molecular hallmarks of developmental potential. In the male germline, these domains are thought to persist into sperm to establish totipotency in the next generation. However, it remains unknown how H3K27me3 is established on specific targets in the male germline. Here, we demonstrate that a germline-specific Polycomb protein, SCML2, binds to H3K4me2/3-rich hypomethylated promoters in undifferentiated spermatogonia to facilitate H3K27me3. Thus, SCML2 establishes bivalent domains in the male germline of mice. SCML2 regulates two major classes of bivalent domains: Class I domains are established on developmental regulator genes that are silent throughout spermatogenesis, while class II domains are established on somatic genes silenced during late spermatogenesis. We propose that SCML2-dependent H3K27me3 in the male germline prepares the expression of developmental regulator and somatic genes in embryonic development.

    View details for DOI 10.1073/pnas.1804512115

    View details for Web of Science ID 000431639100059

    View details for PubMedID 29686098

    View details for PubMedCentralID PMC5949012

  • Elucidation of the Fanconi Anemia Protein Network in Meoisis and Its Function in the Regulation of Histone Modifications CELL REPORTS Alavattam, K. G., Kato, Y., Sin, H., Maezawa, S., Kowalski, I. J., Zhang, F., Pang, Q., Andreassen, P. R., Namekawa, S. H. 2016; 17 (4): 1141-1157


    Precise epigenetic regulation of the sex chromosomes is vital for the male germline. Here, we analyze meiosis in eight mouse models deficient for various DNA damage response (DDR) factors, including Fanconi anemia (FA) proteins. We reveal a network of FA and DDR proteins in which FA core factors FANCA, FANCB, and FANCC are essential for FANCD2 foci formation, whereas BRCA1 (FANCS), MDC1, and RNF8 are required for BRCA2 (FANCD1) and SLX4 (FANCP) accumulation on the sex chromosomes during meiosis. In addition, FA proteins modulate distinct histone marks on the sex chromosomes: FA core proteins and FANCD2 regulate H3K9 methylation, while FANCD2 and RNF8 function together to regulate H3K4 methylation independently of FA core proteins. Our data suggest that RNF8 integrates the FA-BRCA pathway. Taken together, our study reveals distinct functions for FA proteins and illuminates the male sex chromosomes as a model to dissect the function of the FA-BRCA pathway.

    View details for DOI 10.1016/j.celrep.2016.09.073

    View details for Web of Science ID 000385853600018

    View details for PubMedID 27760317

  • FANCB is essential in the male germline and regulates H3K9 methylation on the sex chromosomes during meiosis HUMAN MOLECULAR GENETICS Kato, Y., Alavattam, K. G., Sin, H., Meetei, A. R., Pang, Q., Andreassen, P. R., Namekawa, S. H. 2015; 24 (18): 5234-5249


    Fanconi anemia (FA) is a recessive X-linked and autosomal genetic disease associated with bone marrow failure and increased cancer, as well as severe germline defects such as hypogonadism and germ cell depletion. Although deficiencies in FA factors are commonly associated with germ cell defects, it remains unknown whether the FA pathway is involved in unique epigenetic events in germ cells. In this study, we generated Fancb mutant mice, the first mouse model of X-linked FA, and identified a novel function of the FA pathway in epigenetic regulation during mammalian gametogenesis. Fancb mutant mice were infertile and exhibited primordial germ cell (PGC) defects during embryogenesis. Further, Fancb mutation resulted in the reduction of undifferentiated spermatogonia in spermatogenesis, suggesting that FANCB regulates the maintenance of undifferentiated spermatogonia. Additionally, based on functional studies, we dissected the pathway in which FANCB functions during meiosis. The localization of FANCB on sex chromosomes is dependent on MDC1, a binding partner of H2AX phosphorylated at serine 139 (γH2AX), which initiates chromosome-wide silencing. Also, FANCB is required for FANCD2 localization during meiosis, suggesting that the role of FANCB in the activation of the FA pathway is common to both meiosis and somatic DNA damage responses. H3K9me2, a silent epigenetic mark, was decreased on sex chromosomes, whereas H3K9me3 was increased on sex chromosomes in Fancb mutant spermatocytes. Taken together, these results indicate that FANCB functions at critical stages of germ cell development and reveal a novel function of the FA pathway in the regulation of H3K9 methylation in the germline.

    View details for DOI 10.1093/hmg/ddv244

    View details for Web of Science ID 000361317200014

    View details for PubMedID 26123487

    View details for PubMedCentralID PMC4550819

  • Sex chromosome inactivation in germ cells: emerging roles of DNA damage response pathways CELLULAR AND MOLECULAR LIFE SCIENCES Ichijima, Y., Sin, H., Namekawa, S. H. 2012; 69 (15): 2559-2572


    Sex chromosome inactivation in male germ cells is a paradigm of epigenetic programming during sexual reproduction. Recent progress has revealed the underlying mechanisms of sex chromosome inactivation in male meiosis. The trigger of chromosome-wide silencing is activation of the DNA damage response (DDR) pathway, which is centered on the mediator of DNA damage checkpoint 1 (MDC1), a binding partner of phosphorylated histone H2AX (γH2AX). This DDR pathway shares features with the somatic DDR pathway recognizing DNA replication stress in the S phase. Additionally, it is likely to be distinct from the DDR pathway that recognizes meiosis-specific double-strand breaks. This review article extensively discusses the underlying mechanism of sex chromosome inactivation.

    View details for DOI 10.1007/s00018-012-0941-5

    View details for Web of Science ID 000306335000008

    View details for PubMedID 22382926

    View details for PubMedCentralID PMC3744831

  • A Novel Y Chromosome Microdeletion With the Loss of an Endogenous Retrovirus Related, Testis Specific Transcript in AZFb Region JOURNAL OF UROLOGY Sin, H., Koh, E., Taya, M., Iijima, M., Sugimoto, K., Maeda, Y., Yoshida, A., Iwamoto, T., Namiki, M. 2011; 186 (4): 1545-1552


    We identified the endogenous retroviruses associated with TTYs (testis specific transcripts linked to the Y) in the AZFb region. We evaluated the relationship between endogenous retroviruses, and TTY expression patterns and function in spermatogenesis.We identified family members of TTYs in the AZFb region using computational screening. After investigating the relationship between the endogenous retrovirus genome and TTY expression patterns we screened genomic polymerase chain reaction products from TTY13 amplified from 790 Japanese men, including 275 with azoospermia, 285 with oligozoospermia and 230 who were fertile.Computational screening revealed that 3 members of the TTY family, TTY9, 10 and 13, were regulated by endogenous retroviruses in the AZFb region. Homologous recombination between long terminal repeat of the TTY13 associated human endogenous retrovirus-K14C resulted in TTY13 deletion events. These deletions were more common in patients with azoospermia and oligozoospermia than in fertile males. Specifically 15.63% of the azoospermia group, 10.88% of the oligozoospermia group and 0% of fertile controls had only the deletion variant, indicating an association between the homologous recombination rate and the severity of spermatogenesis failure that was statistically significant (p <0.05).Because of the finding of what are to our knowledge novel microdeletions due to endogenous retrovirus in the AZFb region, our study raises the possibility that specific variations in genomic structure may contribute to some forms of human idiopathic male infertility.

    View details for DOI 10.1016/j.juro.2011.05.044

    View details for Web of Science ID 000295399500119

    View details for PubMedID 21855935

  • Human endogenous retrovirus K14C drove genomic diversification of the Y chromosome during primate evolution JOURNAL OF HUMAN GENETICS Sin, H., Koh, E., Kim, D., Murayama, M., Sugimoto, K., Maeda, Y., Yoshida, A., Namiki, M. 2010; 55 (11): 717-725


    The male-specific region of Y chromosome (MSY) has accumulated a higher density of human endogenous retroviruses (HERVs) and related sequences when compared with other regions of the human genome. Here, we focused on one HERV family, HERV-K14C that seemed to integrate preferentially into the Y chromosome in humans. To identify every copies of HERV-K14C in the human genome, we applied computational screening to map precisely the locus of individual HERV-K14C copies. Interestingly, 29 of all 146 copies were located in Y chromosome, and these 29 copies were mostly dispersed in the palindromic region. Three distinct HERV-K14C-related transcripts were found and were exclusively expressed in human testis tissue. Based on our phylogenetic analysis of the solitary LTRs derived from HERV-K14C on the Y chromosome we suggested that these sequences were generated as pairs of identical sequences. Specifically, analysis of HERV-K14C-related sequences in the palindromic region demonstrated that the Y chromosomal amplicons existed in our common ancestors and the duplicated pairs arose after divergence of great apes approximately 8-10 million years ago. Taken together, our observation suggested that HERV-K14C-related sequences contributed to genomic diversification of Y chromosome during speciation of great ape lineage.

    View details for DOI 10.1038/jhg.2010.94

    View details for Web of Science ID 000284601900002

    View details for PubMedID 20703239

  • Features of constitutive gr/gr deletion in a Japanese population HUMAN REPRODUCTION Sin, H., Koh, E., Shigehara, K., Sugimoto, K., Maeda, Y., Yoshida, A., Kyono, K., Namiki, M. 2010; 25 (9): 2396-2403


    The relationship between male infertility and gr/gr deletions that remove multiple genes of the Y chromosome varies among countries and populations. The aim of this study was to investigate the association between gr/gr deletions and spermatogenic phenotype in fertile and infertile Japanese men.The subjects were screened by sequence-tagged site (STS) analysis to detect gr/gr deletions, and haplogroups were assigned using eight highly informative markers. In total, 395 infertile men and 377 fertile men (controls) participated in our study. Of the 772 subjects, 260 individuals carried confirmed gr/gr deletions and were used in further analysis of deletion subtype and gene copy number, specifically loss and gain of CDY1 and DAZ copies. These 260 subjects were divided into a control group (n = 131) all with normozoospermia, and an infertile group (n = 129) with 89 infertile subjects exhibiting azoospermia (absence of sperm) and 40 exhibiting oligozoospermia (reduced sperm concentration).There were gr/gr deletions in 33.7% (260/772) of all subjects and the deletions were widespread in haplogroup D (86.2%). There were no significant differences in the frequency of gr/gr deletions between the infertile and control groups. The gr/gr deletion subtypes were not distributed randomly among haplogroups; the CDY1a+ DAZ1/2 genes were deleted in 96.9% (217/224) of haplogroup D individuals, whereas the O lineage had a variety of gr/gr deletion types. The loss of CDY1a+ DAZ1/2 was not associated with spermatogenic impairment in haplogroup D (P = 0.33).Taken together, gr/gr deletions in haplogroup D occur constitutively, are associated with the loss of CDY1a + DAZ1/2 and are phenotypically neutral. Further studies are needed to establish whether Y-linked compensatory factors outside the AZFc region can counteract the pathogenic effect of a gr/gr deletion in the D lineage.

    View details for DOI 10.1093/humrep/deq191

    View details for Web of Science ID 000281343700030

    View details for PubMedID 20663794

  • Azoospermia factor and male infertility. Reproductive medicine and biology Koh, E., Sin, H. S., Fukushima, M., Namiki, M. 2010; 9 (3): 129-137


    Recently, work has shown that azoospermia factor (AZF) microdeletions result from homologous recombination between almost identical blocks in this gene region. These microdeletions in the Y chromosome are a common molecular genetic cause of spermatogenetic failure leading to male infertility. After completion of the sequencing of the Y chromosome, the classical definition of AZFa, AZFb, and AZFc was modified to five regions, namely AZFa, P5/proximal-P1, P5/distal-P1, P4/distal-P1, and AZFc, as a result of the determination of Y chromosomal structure. Moreover, partial AZFc deletions have also been reported, resulting from recombination in their sub-ampliconic identical pair sequences. These deletions are also implicated in a possible association with Y chromosome haplogroups. In this review, we address Y chromosomal complexity and the modified categories of the AZF deletions. Recognition of the association of Y deletions with male infertility has implications for the diagnosis, treatment, and genetic counseling of infertile men, in particular candidates for intracytoplasmic sperm injection.

    View details for DOI 10.1007/s12522-010-0055-4

    View details for PubMedID 29699335

    View details for PubMedCentralID PMC5904663

  • Liquid Chromatography-tandem Mass Spectrometry (LC-MS/MS) Assay for Simultaneous Measurement of Salivary Testosterone and Cortisol in Healthy Men for Utilization in the Diagnosis of Late-onset Hypogonadism in Males ENDOCRINE JOURNAL Matsui, F., Koh, E., Yamamoto, K., Sugimoto, K., Sin, H., Maeda, Y., Honma, S., Namiki, M. 2009; 56 (9): 1083-1093


    It is well known that late-onset hypogonadism in males can cause a variety of symptoms, and the differential diagnosis is relatively difficult, including psychological disorders, stress, and mood disturbances. The level of serum cortisol can be measured to reflect a patient's level of stress. Salivary hormones facilitate the evaluation of physiological hormonal actions based on free hormone assay. For the simultaneous measurement of testosterone and cortisol levels in saliva, we validate a sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay. Concerning accuracy and precision, the lower limit of quantification of salivary testosterone and cortisol were established as 5 and 10 pg/mL, respectively. Testosterone and cortisol in saliva is stable for 2 days, 14 days, and 28 days at room temperature, refrigeration and frozen, respectively. Freezing and thawing for 3 cycles and stimulation of salivation with gum chewing do not alter the measured values of testosterone and cortisol. Total, bioavailable, and free serum testosterone showed slight diurnal changes, but total and bioavailable serum cortisol showed marked diurnal changes. Salivary testosterone levels negatively correlate with age, regardless of the time of saliva collection (r=0.64, p<0.05). However, there is no relationship between salivary cortisol and age (r=0033, p>0.05). LC-MS/MS allows rapid, simultaneous, sensitive, and accurate quantification of testosterone and cortisol in saliva for the diagnosis late-onset hypogonadism or other hormone related disease.

    View details for Web of Science ID 000274231100008

    View details for PubMedID 19734692

  • Measurement-specific bioavailable testosterone using concanavalin A precipitation: Comparison of calculated and assayed bioavailable testosterone INTERNATIONAL JOURNAL OF UROLOGY Yamamoto, K., Koh, E., Matsui, F., Sugimoto, K., Sin, H., Maeda, Y., Namiki, M. 2009; 16 (11): 894-901


    To assess the value of calculated bioavailable testosterone (cBT) and assayed BT (aBT) for the diagnosis of late-onset hypogonadism (LOH) in middle-aged and elderly subjects.In order to assay serum BT, sex hormone-binding globulin was precipitated with concanavalin-A and then testosterone was measured using liquid chromatography-tandem mass spectrometry. To validate the non-sex-hormone-binding-globulin-bound testosterone, gel filtration chromatography and concanavalin-A sepharose were used. Following this validation, the usefulness between aBT and cBT was evaluated in clinical samples.Eighty-eight healthy male volunteers (mean age 65.6 years, range: 50-86) were recruited for this study. A significant correlation was found between cBT and aBT (R(2) = 0.53, P < 0.01). Mean value ratio (cBT/aBT) was 2.48. Both cBT (R(2) = 0.122) and aBT (R(2) = 0.251) decreased with age. Variations in aBT were less marked than those for cBT, suggesting that aBT can be used to determine age-related reduced testosterone levels.aBT levels are more reliable than cBT levels for the diagnosis of LOH in middle-aged and elderly subjects.

    View details for DOI 10.1111/j.1442-2042.2009.02379.x

    View details for Web of Science ID 000271002700009

    View details for PubMedID 19744252

  • Single Nucleotide Polymorphism Analysis of the Follicle-stimulating Hormone (FSH) Receptor in Japanese with Male Infertility: Identification of Codon Combination with Heterozygous Variations of the Two Discrete FSH Receptor Gene ENDOCRINE JOURNAL Shimoda, C., Koh, E., Yamamoto, K., Matsui, F., Sugimoto, K., Sin, H., Maeda, Y., Kanaya, J., Yoshida, A., Namiki, M. 2009; 56 (7): 859-865


    Dysfunction of the FSH receptor (FSHR) may be involved in some form of male infertility with azoospermia or oligozoospermia. We assessed the discrete codon combination with homo/heterozygous variation of the exon 10 in the FSHR gene.The genotype of codon 307 and codon 680 were analysed in 352 patients with idiopathic male infertility and 145 men with proven fertility.There was no significant difference in the distributions of each homozygous codon 307 or 680 between these two groups as reported in the literature. However, the population with heterozygous combinations Thr/Ala (codon 307) and Ser/ Asn (codon 680) comprised 26% (38/146) and 44.9% (157/343) in subjects with proven fertility and idiopathic infertile men, respectively. Moreover, the heterozygous genotype Thr/Ala-Ser/Asn was significantly increased in infertile patients compared with the controls. This finding showed that the combination of heterozygous FSHR can be responsible for male infertility.

    View details for Web of Science ID 000271260400005

    View details for PubMedID 19550076

  • Tissue-specific differentially methylated regions of the human VASA gene are potentially associated with maturation arrest phenotype in the testis JOURNAL OF HUMAN GENETICS Sugimoto, K., Koh, E., Sin, H., Maeda, Y., Narimoto, K., Izumi, K., Kobori, Y., Kitamura, E., Nagase, H., Yoshida, A., Namiki, M. 2009; 54 (8): 450-456


    Numerous CpG islands containing tissue-specific differentially methylated regions (TDMRs) are potential methylation sites in normal cells and tissues. The VASA (also known as DDX4) gene is believed to be under the control of TDMRs. A total of 131 male patients with idiopathic azoospermia or severe oligospermia were evaluated histologically, and the methylation status of CpG islands in the VASA gene was screened. Genome DNAs were obtained from testicular biopsy and modified with sodium bisulfite, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was applied. This system is capable of analyzing both the methylated and unmethylated CpG island in the genome. The methylation analysis is conducted by an epigram as graphic data. On histological assessment, 17 of 131 patients revealed maturation arrest (MA).In all, 6 of the 17 patients showed particularly high VASA TDMR methylation rates, whereas the remaining 11 patients and controls had low methylation rates. This study may imply that the VASA TDMR methylation is significantly higher among patients with MA, in whom the VASA gene expression was silenced. This finding represents an important contribution to the molecular basis of meiotic arrest as one possible cause of idiopathic infertility.

    View details for DOI 10.1038/jhg.2009.59

    View details for Web of Science ID 000269939000003

    View details for PubMedID 19629140

  • Endogenous retrovirus-related sequences provide an alternative transcript of MCJ genes in human tissues and cancer cells GENES & GENETIC SYSTEMS Sin, H., Huh, J., Kim, D., Kim, T., Ha, H., Kim, W., Park, H., Kim, C., Kim, H. 2006; 81 (5): 333-339


    The MCJ gene is a member of the DNAJ family, and its transcriptional event is controlled by methylation of the CpG island. In our study, we found LTR33 and LTR7 elements provided an alternative transcript within the MCJ gene. To detect different expression patterns between the originally reported MCJ transcript and the LTR-related transcript, we performed a RT-PCR approach using various human tissues and cancer cells. The original MCJ transcript was detected in human tissues and cancer cells, whereas the LTR-related transcript was only revealed in some cancer cells (HCT106, MCF-3, TE-1, Hela, and CCHM). We also performed a PCR analysis to compare the insertion lineage of the LTR elements with the genomic DNAs of primates, indicating that those LTR33 and LTR7 elements of HERV-H have been integrated into the primate genome at different times. Taken together, we suggest that HERV-related elements trigger transcriptome diversification during primate evolution.

    View details for Web of Science ID 000243847000004

    View details for PubMedID 17159294

  • Transcriptional control of the HERV-H LTR element of the GSDML gene in human tissues and cancer cells ARCHIVES OF VIROLOGY Sin, H., Huh, J., Kim, D., Kang, D. W., Min, D. S., Kim, T., Ha, H., Kim, H., Lee, S., Kim, H. 2006; 151 (10): 1985-1994


    Long terminal repeats (LTRs) of human endogenous retroviruses (HERVs) have been reported to serve as alternative promoters in functional genes. The GSDML (gasdermin-like protein) gene located on human chromosome 17q21 has been found to be an oncogenomic recombination hotspot. Here, we identified the LTR element of HERV-H with reverse orientation as an alternative promoter of the GSDML gene and analyzed its expression pattern in human tissues and cancer cells. A reporter gene assay of the promoter activity of the LTR on the GSDML gene in human cancer cell lines (HCT-116 and HeLa) and a kidney cell line (Cos7) of African green monkey indicated that the LTR promoter with reverse orientation had stronger promoter activity than forward one. The transcripts of this LTR-derived promoter were widely distributed in various human tissues and cancer cells, whereas the transcripts of the cellular promoter were found only in stomach tissues and some cancer cells (HCT116, MCF7, U937, C-33A, and PC3). These findings suggest that the LTR element on the GSDML gene was integrated into the hominoid lineage and acquired the role of transcriptional regulation of human tissues and cancer cells.

    View details for DOI 10.1007/s00705-006-0764-5

    View details for Web of Science ID 000240723300007

    View details for PubMedID 16625320

  • Molecular evolution of the periphilin gene in relation to human endogenous retrovirus M element JOURNAL OF MOLECULAR EVOLUTION Huh, J., Kim, T., Yi, J., Park, E., Kim, W., Sin, H., Kim, D., Min, D., Kim, S., Kim, C., Hyun, B., Kang, S., Jung, J., Lee, W., Takenaka, O., Kim, H. 2006; 62 (6): 730-737


    HERV-M (human endogenous retrovirus M), related to the super family of HERV-K, has a methionine (M) tRNA primer-binding site, and is located within the periphilin gene on human chromosome 12q12. HERV-M has been integrated into the periphilin gene as the truncated form, 5'LTR-gag-pol-3'LTR. Polymerase chain reaction (PCR) and reverse transcription-polymerase chain reaction (RT-PCR) approaches were conducted to investigate its evolutionary origins. Interestingly, the insertion of retroelements in a common ancestor genome can make different transcript variants in different species. In the case of the periphilin gene, human (10 variants) and mouse (2 variants) lineages show different transcript variants. Insertion of HERV-M (variant 1-3) could affect the protein-coding region. Also, Alusq/x (variant 4-9) and L1ME4a (mammalian-wide subfamilies of LINE-1) (variant 10) in humans and SINE (short interspersed repetitive element) and RLTR15 (the mouse putative long terminal repeat) (variant 2) in mice could be driving forces in transcript diversification of the periphilin gene during mammalian evolution. The HERV-M derived transcripts (variant 1-3) were expressed in different human tissues, whereas they were not detected in crab-eating monkey and squirrel monkey tissues by RT-PCR amplification. Taken together, HERV-M seems to have been integrated into our common ancestor genome after the divergence of simians and prosimians, and then was actively expressed during hominoid evolution.

    View details for DOI 10.1007/s00239-005-0109-0

    View details for Web of Science ID 000238035500008

    View details for PubMedID 16612547