Biomedical subjects

Satoshi Tanaka

Publications and source records attributed to Satoshi Tanaka.

At least 19 recordsLinked to original sources

PubMed2026

PUF60 is a Critical Regulator of PKM Splicing During Myogenesis.

Pyruvate kinase M (PKM) catalyzes the conversion of phosphoenolpyruvate to pyruvate in glycolysis and exists as two splice isoforms, PKM1 and PKM2, generated from alternative splicing of mutually exclusive exons 9 or 10, respectively. The expression balance between PKM1 and PKM2 is tightly regulated in a cell-type-specific manner. PKM1 is predominantly expressed in tissues such as skeletal muscle, heart, and brain, whereas PKM2 is prevalent in most other tissues and various cancer cells. Despite its importance, the trans-acting factors promoting exon 9 selection in a tissue-specific context remain largely unknown. Here, using a multi-color splicing reporter system for cell-based cDNA screening, we identified PUF60 as a novel trans-acting factor that promotes PKM1-type splicing. We also demonstrated that PUF60 induction and the resulting splicing switch are essential for myotube formation during C2C12 differentiation. This study establishes PUF60 as a critical regulator of muscle-specific splicing and provides new insights into the fundamental mechanisms governing skeletal muscle differentiation.

Animals↗

PubMed2007

T cell self-reactivity forms a cytokine milieu for spontaneous development of IL-17+ Th cells that cause autoimmune arthritis.

This report shows that highly self-reactive T cells produced in mice as a result of genetically altered thymic T cell selection spontaneously differentiate into interleukin (IL)-17-secreting CD4+ helper T (Th) cells (Th17 cells), which mediate an autoimmune arthritis that clinically and immunologically resembles rheumatoid arthritis (RA). The thymus-produced self-reactive T cells, which become activated in the periphery via recognition of major histocompatibility complex/self-peptide complexes, stimulate antigen-presenting cells (APCs) to secrete IL-6. APC-derived IL-6, together with T cell-derived IL-6, drives naive self-reactive T cells to differentiate into arthritogenic Th17 cells. Deficiency of either IL-17 or IL-6 completely inhibits arthritis development, whereas interferon (IFN)-gamma deficiency exacerbates it. The generation, differentiation, and persistence of arthritogenic Th17 cells per se are, however, insufficient for producing overt autoimmune arthritis. Yet overt disease is precipitated by further expansion and activation of autoimmune Th17 cells, for example, via IFN-gamma deficiency, homeostatic proliferation, or stimulation of innate immunity by microbial products. Thus, a genetically determined T cell self-reactivity forms a cytokine milieu that facilitates preferential differentiation of self-reactive T cells into Th17 cells. Extrinsic or intrinsic stimuli further expand these cells, thereby triggering autoimmune disease. Intervention in these events at cellular and molecular levels is useful to treat and prevent autoimmune disease, in particular RA.

Animals↗

PubMed2007

Genome-wide and locus-specific DNA hypomethylation in G9a deficient mouse embryonic stem cells.

In the mammalian genome, numerous CpG-rich loci define tissue-dependent and differentially methylated regions (T-DMRs). Euchromatin from different cell types differs in terms of its tissue-specific DNA methylation profile as defined by these T-DMRs. G9a is a euchromatin-localized histone methyltransferase (HMT) and catalyzes methylation of histone H3 at lysines 9 and 27 (H3-K9 and -K27). To test whether HMT activity influences euchromatic cytosine methylation, we analyzed the DNA methylation status of approximately 2000 CpG-rich loci, which are predicted in silico, in G9a(-/-) embryonic stem cells by restriction landmark genomic scanning (RLGS). While the RLGS profile of wild-type cells contained about 1300 spots, 32 new spots indicating DNA demethylation were seen in the profile of G9a(-/-) cells. Virtual-image RLGS (Vi-RLGS) allowed us to identify the genomic source of ten of these spots. These were confirmed to be cytosine demethylated, not just at the Not I site detected by the RLGS but extending over several kilobase pairs in cis. Chromatin immunoprecipitation (ChIP) confirmed these loci to be targets of G9a, with decreased H3-K9 and/or -K27 dimethylation in the G9a(-/-) cells. These data indicate that G9a site-selectively contributes to DNA methylation.

Animals↗

PubMed2006

Interaction of ERp57 and tapasin in the generation of MHC class I-peptide complexes.

Antigen presentation by MHC class I molecules is necessary for CD8 T-cell activation. Optimal peptide loading onto MHC class I molecules occurs mainly in the peptide-loading complex in the endoplasmic reticulum. The identification of a covalent association between the thiol oxidoreductase ERp57 and tapasin, and its impact on the loading complex, are important recent developments in this field of research. In the absence of ERp57, the recruitment of MHC class I molecules into this complex by tapasin is greatly impaired both in the number of molecules and in their interaction time, suggesting a key structural role for the ERp57-tapasin association in the peptide-loading complex. The role of ERp57 as a thiol oxidoreductase in the peptide-loading complex remains, however, controversial and further research regarding this subject is required.

Animals↗

PubMed2006

PGC7/Stella protects against DNA demethylation in early embryogenesis.

DNA methylation is an important means of epigenetic gene regulation and must be carefully controlled as a prerequisite for normal early embryogenesis. Although global demethylation occurs soon after fertilization, it is not evenly distributed throughout the genome. Genomic imprinting and epigenetic asymmetry between parental genomes, that is, delayed demethylation of the maternal genome after fertilization, are clear examples of the functional importance of DNA methylation. Here, we show that PGC7/Stella, a maternal factor essential for early development, protects the DNA methylation state of several imprinted loci and epigenetic asymmetry. After determining that PGC7/Stella binds to Ran binding protein 5 (RanBP5; a nuclear transport shuttle protein), mutant versions of the two proteins were used to examine exactly when and where PGC7/Stella functions within the cell. It is likely that PGC7/Stella protects the maternal genome from demethylation only after localizing to the nucleus, where it maintains the methylation of several imprinted genes. These results demonstrate that PGC7/Stella is indispensable for the maintenance of methylation involved in epigenetic reprogramming after fertilization.

Animals↗

PubMed2006

Ruptured pediatric posterior cerebral artery aneurysm 9 years after the onset of Kawasaki disease: a case report.

CASE REPORT: A 12-year-old boy who had a history of Kawasaki disease 9 years ago experienced a subarachnoid hemorrhage by ruptured right posterior cerebral artery aneurysm. On day 1 operation, as the aneurysm was very fragile and bled easily, two intraoperative ruptures, including a very premature rupture, were encountered. As a result, a left hemiparesis especially severe in the left hand was caused by the right anterior thalamic infarction due to the occlusion of a thalamo-perforating artery arising near the neck of the aneurysm. DISCUSSION: The histopathological examination of the intraoperative excised aneurysmal dome disclosed the thickening of the endothelial inner due to the endothelial hypertrophy and the invasion of inflammatory cells. This finding of the aneurysm was partially mimicking the finding of the coronary artery of the patients with Kawasaki disease. The combination of cerebral aneurysm and Kawasaki disease has never been reported until now, and the etiology of the aneurysm of this patient is unclear.

Aneurysm, Ruptured↗

PubMed2006

Dimethyl sulfoxide has an impact on epigenetic profile in mouse embryoid body.

Dimethyl sulfoxide (DMSO), an amphipathic molecule, is widely used not only as a solvent for water-insoluble substances but also as a cryopreservant for various types of cells. Exposure to DMSO sometimes causes unexpected changes in cell fates. Because mammalian development and cellular differentiation are controlled epigenetically by DNA methylation and histone modifications, DMSO likely affects the epigenetic system. The effects of DMSO on transcription of three major DNA methyltransferases (Dnmts) and five well-studied histone modification enzymes were examined in mouse embryonic stem cells and embryoid bodies (EBs) by reverse transcription-polymerase chain reaction. Addition of DMSO (0.02%-1.0%) to EBs in culture induced an increase in Dnmt3a mRNA levels with increasing dosage. Increased expression of two subtypes of Dnmt3a in protein levels was confirmed by Western blotting. Southern blot analysis revealed that DMSO caused hypermethylation of two kinds of repetitive sequences in EBs. Furthermore, restriction landmark genomic scanning, by which DNA methylation status can be analyzed on thousands of loci in genic regions, revealed that DMSO affected DNA methylation status at multiple loci, inducing hypomethylation as well as hypermethylation depending on the genomic loci. In conclusion, DMSO has an impact on the epigenetic profile: upregulation of Dnmt3a expression and alteration of genome-wide DNA methylation profiles with phenotypic changes in EBs.

Animals↗

PubMed2006

Equivalency of nuclear transfer-derived embryonic stem cells to those derived from fertilized mouse blastocysts.

Therapeutic cloning, whereby nuclear transfer (NT) is used to generate embryonic stem cells (ESCs) from blastocysts, has been demonstrated successfully in mice and cattle. However, if NT-ESCs have abnormalities, such as those associated with the offspring produced by reproductive cloning, their scientific and medical utilities might prove limited. To evaluate the characteristics of NT-ESCs, we established more than 150 NT-ESC lines from adult somatic cells of several mouse strains. Here, we show that these NT-ESCs were able to differentiate into all functional embryonic tissues in vivo. Moreover, they were identical to blastocyst-derived ESCs in terms of their expression of pluripotency markers in the presence of tissue-dependent differentially DNA methylated regions, in DNA microarray profiles, and in high-coverage gene expression profiling. Importantly, the NT procedure did not cause irreversible damage to the nuclei. These similarities of NT-ESCs and ESCs indicate that murine therapeutic cloning by somatic cell NT can provide a reliable model for preclinical stem cell research.

Animals↗

PubMed2006

Loss of the maternal imprint in Dnmt3Lmat-/- mice leads to a differentiation defect in the extraembryonic tissue.

DNA methylation of the genome is essential for mammalian development and plays crucial roles in a variety of biological processes including genomic imprinting. Although the DNA methyltransferase 3-like (Dnmt3L) protein lacks DNA methylase activity, it is thought to establish the maternal imprint in combination with the functional DNA methyltransferases. Oogenesis apparently proceeds normally in female mice homozygous for a targeted deletion of Dnmt3L, but their heterozygous offspring (Dnmt3L(mat-/-)) die before midgestation due to an imprinting defect. In this study, we show that Dnmt3L is required for the establishment of maternal methylation imprints both in the embryos and the placentae and that the placentae of these embryos develop abnormally. There is a defect in the formation of the labyrinth, reduced formation of the spongiotrophoblast layer, excess trophoblast giant cells and insufficient attachment between the chorion layer and the ectoplacental cone. In addition, we demonstrate arrest of proliferation of the extraembryonic tissue without apoptosis in vivo and a disturbance of the cell fate of Dnmt3L(mat-/-) trophoblastic stem cells in vitro. Furthermore, we report that DNA methylation during oogenesis is essential for the establishment of imprinting Mash2. These findings provide evidence that not only is DNA methylation required for the appropriate maternal imprint in the placenta but that the appropriate imprint is absolutely required for vertebrate placentation.

Animals↗

PubMed2006

Recent advances in molecular pharmacology of the histamine systems: immune regulatory roles of histamine produced by leukocytes.

Accumulating evidence has highlighted the importance of histamine in immune responses. The H1 receptor is involved not only in allergic inflammatory reactions but also in augmentation of helper T cell (Th)1 responses, whereas H2 receptor suppresses Th responses and participates in immune tolerance through interleukin-10 and transforming growth factor-beta. Identification of the H4 receptor, which binds to histamine with high affinity and of which expression is limited to the hematopoietic system, has enhanced the importance of histamine in immune responses. However, since a majority of previous studies has evaluated the effects of exogenous histamine, it remains largely unknown how endogenously produced histamine is involved in regulation of such kinds of immune responses. Insight into precise roles of histamine in the immune system can not be obtained without correct understanding of both the predominance of a certain type of histamine receptor and the regulation of histamine synthesis. Here we review a part of the recent progress in histamine research in the field of immunology with attention to the source of involved histamine.

Histamine↗

PubMed2006

DNA methylation-dependent epigenetic regulation of dimethylarginine dimethylaminohydrolase 2 gene in trophoblast cell lineage.

Trophoblast cell lineage is established through the first cellular differentiation in mammalian embryogenesis, and its developmental potential is restricted to the extraembryonic tissues contributing solely to the placenta. Several lines of evidence suggest a relative lack of importance of DNA methylation in gene regulation in the extraembryonic tissues when compared with embryonic ones. Here we analyzed the dynamics of epigenetic status in the upstream region of mouse Ddah2 gene, which was found to be specifically repressed in a stem cell population of trophoblast cell lineage. We found a tissue-dependent differentially methylated region in the regulatory region of the Ddah2 gene. This region was hypermethylated in trophoblast stem cells and was hypomethylated in differentiated cells both in vivo and in vitro. This change was well correlated with Ddah2 expression. In addition, in vitro methylation confined to the differentially methylated region was sufficient to repress promoter activity in the reporter assay. Furthermore, a repressive pattern of histone modifications was formed around the differentially methylated region in undifferentiated trophoblast stem cells with repressed Ddah2. Our data suggest that DNA methylation-mediated chromatin remodeling is involved in the regulation of the Ddah2 gene expression and thus is important even in trophoblast cell lineage.

Amidohydrolases↗

PubMed2006

Proliferation related acidic leucine-rich protein PAL31 functions as a caspase-3 inhibitor.

Proliferation related acidic leucine-rich protein PAL31 (PAL31) is expressed in proliferating cells and consists of 272 amino acids with a tandem structure of leucine-rich repeats in the N-terminus and a highly acidic region with a putative nuclear localization signal in the C-terminus. We previously reported that PAL31 is required for cell cycle progression. In the present study, we found that the antisense oligonucleotide of PAL31 induced apoptosis to the transfected Nb2 cells. Stable transfectants, in which PAL31 was regulated by an inducible promoter, were generated to gain further insight into the signaling role of PAL31 in the regulation of apoptosis. Expression of PAL31 resulted in the marked rescue of Rat1 cells from etoposide and UV radiation-induced apoptosis and the cytoprotection was correlated with the levels of PAL31 protein. Thus, cytoprotection from apoptosis is a physiological function of PAL31. PAL31 can suppress caspase-3 activity but not cytochrome c release in vitro, indicating that PAL31 is a direct caspase-3 inhibitor. In conclusion, PAL31 is a multifunctional protein working as a cell cycle progression factor as well as a cell survival factor.

Animals↗

PubMed2006

Effects of lumbar sympathetic ganglion block for a patient with amyotrophic lateral sclerosis (ALS).

A 59-year-old man with amyotrophic lateral sclerosis (ALS) received lumbar epidural and sympathetic ganglion blocks to increase regional blood flow and improve his clinical symptoms. After a lumbar epidural block (0.5% mepivacaine), the skin temperature of his affected lower extremities rose by 7.0 degrees C and became close to that of the intact side, and the distance he was able to walk with his cane increased from 2 to 8 m. The clinical effects produced by the lumbar sympathetic ganglion block (99.5% alcohol) were sustained for approximately 8 weeks after the first block and for approximately 6 weeks after the second block. There were no particular adverse effects or complications associated with these nerve block procedures. Epidural and sympathetic ganglion blocks for an ALS patient, albeit their effects are of a transient nature, may improve related clinical symptoms, and were thought to play a contributory role in improving our patient's quality of life.

Amyotrophic Lateral Sclerosis↗

PubMed2006

A Study for a retrieved implant of ceramic-on-ceramic total hip arthroplasty.

A Mittelmeier-type ceramic on ceramic total hip arthroplasty (THA) was retrieved because of aseptic loosening 17 years after implantation. The extent of wear was assessed by scanning electron microscopy. The synovial fluid and the tissue surrounding the implant were also examined. Scanning electron microscopy analysis of the ball head showed that the main wear zone had grade IV wear. The stripe wear zones showed grain pullout regions (grade 5 wear). Pathologically, chronic inflammation was observed in the surrounding tissue. The debris particles in the synovial fluid were polygonal and approximately 3 x 4 microm. Thus, the Mittelmeier-type THA proved excellent wear resistance. Further longevity of ceramic on ceramic THA may indeed become a reality with improvement of the design and quality of alumina.

Arthroplasty, Replacement, Hip↗

PubMed2006

Trophoblast stem cells.

At the first cell fate decision in mammalian development, the origins of trophoblast and embryonic cell lineages are established as the trophectoderm and the inner cell mass (ICM) in the blastocyst. In the trophoblast cell lineage, a subset of the trophectoderm cells maintains the capacity to proliferate and contribute to the extraembryonic ectoderm, the ectoplacental cone, and the secondary giant cells of the early conceptus after implantation, and finally they produce the entire trophoblastic population in the mature placenta. The stem cell population of the trophectoderm lineage can be isolated and maintained in vitro in the presence of fibroblast growth factor 4, heparin, and a feeder layer of mouse embryonic fibroblast cells. These apparently immortal stem cells in culture are termed trophoblast stem (TS) cells, and exhibit the potential to differentiate into multiple trophoblastic cell types in vitro, as well as in vivo. Even after multiple passages, TS cells retain the ability to participate in the normal development of chimeras and contribute exclusively to the trophoblastic component of the placenta and of the parietal yolk sac. The fate of TS cells is strikingly in contrast to that of embryonic stem cells, which never contribute to these tissues. In this chapter, detailed protocols for the isolation and establishment of TS cell lines from blastocysts and their maintenance are described.

Animals↗

PubMed2006

High expression of ubiquitin carboxy-terminal hydrolase-L1 and -L3 mRNA predicts early recurrence in patients with invasive breast cancer.

The present study investigated the mRNA expression level of ubiquitin c-terminal hydrolase (UCH)-L1 and -L3 in breast cancer tissue and aimed to elucidate its association with tumor characteristics and patient prognosis. UCH-L1 and UCH-L3 mRNA levels in invasive breast cancer (n = 100) were determined by a real-time polymerase chain reaction (PCR) assay and their relationship with various clinicopathological characteristics of breast tumors as well as patient prognosis were studied. UCH-L3 mRNA level was significantly upregulated in breast cancer tissue compared to adjacent normal breast tissue (P < 0.005), and UHC-L1 mRNA level also showed a non-significant increase in tumor tissue compared to adjacent normal breast tissue. Both UCH-L1 and UCH-L3 mRNA levels were significantly higher in high histological grade tumors than in low histological grade tumors (P < 0.001 and P < 0.005, respectively). High UCH-L1 mRNA level was significantly associated with negative estrogen receptor status (P < 0.05) and negative progesterone receptor status (P < 0.05). Patients with both UCH-L1 and UCH-L3 mRNA high tumors showed a significantly poorer prognosis than those in the UCH-L1 or UCH-L3 mRNA low group (P < 0.005). These observations that UCH-L3 mRNA level is upregulated in breast cancer tissue, and breast tumors with both UCH-L1 and UCH-L3 mRNA high expression are associated with a poor prognosis, suggest the possible involvement of UCH-L1 and UCH-L3 in the pathogenesis and progression of breast cancer.

Antigens, CD↗

PubMed2006

Sox15 enhances trophoblast giant cell differentiation induced by Hand1 in mouse placenta.

Some members of the Sry-type HMG box (Sox) protein family play important roles in embryogenesis as transcription factors. Here, we report that Sox15 transcripts were much more abundant in mouse placenta than in the fetus, the yolk sac, or several adult tissues. In situ hybridization analysis of the mouse E8.0 conceptus indicated that Sox15 mRNA was predominantly expressed in the trophoblast giant cells of the placenta. We also observed that the amount of Sox15 mRNA dramatically increased during the differentiation of mouse trophoblast stem cells. Ectopic expression of Sox15 in Rat choriocarcinoma cells enhanced the giant cell differentiation induced by a bHLH transcription factor, Hand1. Binding experiments in cotransfected 293 T cells and in vitro revealed that Sox15 interacted with Hand1. We next examined the effects of this interaction on the transcriptional activity of Hand1 and Sox15 using the luciferase reporter assay. Overexpression of Hand1 repressed the Sox15-driven reporter expression, but Sox15 enhanced the Hand1-driven transcription. This enhancement required both the Hand1-binding region and the transactivation domain of Sox15. These results may suggest that the increased transcriptional activity of Hand1 caused by Sox15 might promote the transcription of the target gene resulting in the trophoblast giant cell differentiation in the mouse placenta.

Animals↗

PubMed2006

Derivation and culture of mouse trophoblast stem cells in vitro.

In the mouse preimplantation embryo, the first cell fate determination segregates two morphologically and functionally distinct cell lineages. One is the inner cell mass, and the other is the trophectoderm. A subset of the trophectoderm maintains a proliferative capacity and forms the extraembryonic ectoderm, the ectoplacental cone, and the secondary giant cells of the early conceptus after implantation. A stem cell population of the trophectoderm lineage can be isolated and maintained in vitro under the presence of fibroblast growth factor 4, heparin, and a feeder layer of mouse embryonic fibroblast cells. Such apparently immortal stem cells, trophoblast stem (TS) cells, exhibit the potential to differentiate to multiple cell types in vitro. TS cells also have the ability to contribute to normal development in chimeras. However, TS cells exclusively contribute to the trophoblastic component of the placenta and of the parietal yolk sac, making a striking contrast with embryonic stem cells, which never contribute to these tissues in chimeras. In this chapter, detailed protocols for the isolation and establishment of TS cell lines from blastocysts and their maintenance are described.

Animals↗