Biomedical subjects

Kenji Sugiyama

Publications and source records attributed to Kenji Sugiyama.

At least 19 recordsLinked to original sources

PubMed2006

Improvements in motor behavioral tests during deep brain stimulation of the subthalamic nucleus in rats with different degrees of unilateral parkinsonism.

Deep brain stimulation (DBS) improves motor performance in Parkinson's disease (PD) patients. To evaluate the effects of subthalamic nucleus (STN)-DBS on impaired motor behavior, we studied improvements in motor performance after delivery of unilateral stimulation to the STN in rats with mild and severe lesions of the nigrostriatal dopamine system caused by injecting 6-hydroxydopamine into the striatum. The rats were trained and performed motor behavioral tests including rotational behavior test, stepping test, and rotarod test before and after receiving DBS. We demonstrated that stimulation at a current strength of 200 microA, which stopped most of the D-amphetamine-induced rotational behaviors in these two groups, improved movement impairments in both the mild and severe groups and that the improvements in the mild group were significantly better than those in the severe group. More experimental and clinical studies are needed to evaluate the efficiency of STN-DBS for different stages of PD.

Amphetamine↗

PubMed2006

Relationship of stimulation site location within the subthalamic nucleus region to clinical effects on parkinsonian symptoms.

OBJECTIVE: To determine the relationship of the stimulation site in the subthalamic region to the clinical effects on parkinsonian symptoms, the monopolar stimulation of 4 electrode contacts and the resulting effects on parkinsonian symptoms were evaluated. METHODS: Seventeen consecutive patients (3 males and 14 females) were enrolled in the study. The patients were evaluated while in a nonmedicated state, and 10-20 min after switching on the pulse generator the effects of stimulation were assessed using separate-subset Unified Parkinson's Disease Rating Scale scores. RESULTS: The relationship between the site stimulated and the percent improvement was analyzed using polynomial regression. Rigidity (p = 0.0004, R2 = 0.15), akinesia (p = 0.02, R2 = 0.07) and total score (p = 0.009, R2 = 0.089) well fit to second-order polynomial regression and showed the greatest improvement after stimulation at 0-1 mm below the horizontal anterior-posterior commissure (AC-PC) plane. Tremor (p = 0.24, R2 = 0.18) and gait (p = 0.36, R2 = 0.001) had a weak relation to the site stimulated, but stimulation at the sites 0-1 mm below the AC-PC plane also produced greater improvement than stimulation at more ventral or dorsal sites. The percent improvement of the posture (p = 0.92, R2 = 0.002) had no relation to the site stimulated. The dorsal border of the subthalamic nucleus was located 0.6 +/- 1.2 mm (n = 27) below the AC-PC plane and the most effective electrode contact 1.2 +/- 1.3 mm (n = 27) below it. CONCLUSIONS: Stimulation around the dorsal border of the subthalamic nucleus, close to the AC-PC plane, produces greater improvement of parkinsonian symptoms than stimulation at more ventral or dorsal sites.

Aged↗

PubMed2006

Sumoylation of Daxx regulates IFN-induced growth suppression of B lymphocytes and the hormone receptor-mediated transactivation.

Daxx has been shown to play an essential role in type I IFN-mediated suppression of B cell development and apoptosis. Recently, we demonstrated that Tyk2 is directly involved in IFN signaling for the induction and translocation of Daxx, which may result in growth arrest and/or apoptosis of B lymphocyte progenitors. To clarify the molecular mechanisms of how Daxx acts on growth suppression of B lymphocytes, we examined functions of a sumoylation-defective Daxx KA mutant (Daxx K630/631A), which substituted Lys 630 and Lys 631 to Ala. Importantly, Daxx KA localized in the cytoplasm, whereas wild-type Daxx localized in the nucleus. Murine pro-B cell line Ba/F3 expressing Daxx KA revealed a resistance to the IFN-induced growth suppression. It is noteworthy that treatment with an exportin inhibitor, leptomycin B, resulted in nuclear localization of Daxx KA and recovery of the IFN-induced growth suppression in Ba/F3 cells. Moreover, Daxx KA decreased the binding potential to promyelocytic leukemia protein (PML), and overexpression of PML recruited Daxx KA into PML oncogenic domains. Notably, a Daxx-small ubiquitin-related modifier fusion protein exhibited increased nuclear localization and ability to suppress cell growth in Ba/F3 cells. These results demonstrate that the IFN-induced growth suppression of B lymphocytes requires nuclear localization of Daxx through its sumoylation and proper interactions with PML.

Active Transport, Cell Nucleus↗

PubMed2006

The stepping test and its learning process in different degrees of unilateral striatal lesions by 6-hydroxydopamine in rats.

Four different levels of the nigrostriatal dopamine system lesions were produced by injections of 6-hydroxydopamine at one-, two-, three-, or four-sites in the striatum and drug-induced rotational movement and stepping test were performed to evaluate behavioral impairments in the rat model of Parkinson's disease. A dose-dependent progressive loss of tyrosine hydroxylase-positive cells in the substance nigra pars compacta was observed in rats with striatal lesion from one- to four-sites. Though the differences in the rotational behavior and stepping test between the lesioned and control rats were highly significant, there were no differences in those behaviors among four groups of lesioned rats. During observation of these behavioral tests, the authors found that the times of trials required for acquisition of the stepping test on the first day of training, which reflected learning acuity, increased in a dose-dependent manner in the lesioned rats as compared with the controls. On the contrary, the times of trials on the next day and in the next week, which reflected retention of the acquired memories, were not different among the groups. In conclusion, the rotational movement and stepping test were not sensitive enough to distinguish severity of the striatal lesions, and learning acuity, but not retention of memories, was disturbed by the striatal lesions.

Animals↗

PubMed2005

Physical and functional interactions between STAT3 and Kaposi's sarcoma-associated herpesvirus-encoded LANA.

The Kaposi's sarcoma-associated herpesvirus (KSHV)-encoded latency-associated nuclear antigen (LANA) is known to modulate viral and cellular gene expression. We show that LANA directly associates with an interleukin-6 signal transducer, signal transducer and activator of transcription 3 (STAT3) and that LANA enhances the transcriptional activity of STAT3. Coimmunoprecipitation studies documented a physical interaction between LANA and STAT3 in transiently transfected 293T cells as well as the KSHV-infected primary effusion lymphoma (PEL) cell line. Furthermore, small-interfering RNA-mediated reduction of LANA expression decreased the STAT3-dependent transcription in KSHV-positive PEL cells, whereas overexpression of LANA enhanced STAT3 activity in KSHV-negative B lymphoma cells. These data demonstrate that LANA is a transcriptional co-activator of STAT3, and may have implications for the pathogenesis of KSHV-associated diseases.

Antigens, Viral↗

PubMed2005

Phosphorylation of threonine-265 in Zipper-interacting protein kinase plays an important role in its activity and is induced by IL-6 family cytokines.

Zipper-interacting protein kinase (ZIPK) is a widely expressed serine/threonine kinase that has been implicated in cell death and transcriptional regulation, but its mechanism of regulation remains unknown. Here, we identified threonine-265 (Thr265) in ZIPK as a major autophosphorylation site. Mutational analyses revealed that autophosphorylation of Thr265 were essential for its full catalytic activity toward an exogenous substrate as well as for cell death induction. Furthermore, leukemia inhibitory factor (LIF) stimulated Thr265 phosphorylation of ZIPK, thereby leading to phosphorylation and activation of signal transducer and activator of transcription (STAT3). Taken together, our findings demonstrate that ZIPK is positively regulated through Thr265 phosphorylation and that this phosphorylation is essential for its function.

Animals↗

PubMed2005

Nuclear retention of STAT3 through the coiled-coil domain regulates its activity.

Signal transducer and activator of transcription 3 (STAT3), which mediates biological actions in many physiological processes, is activated by cytokines and growth factors via specific tyrosine phosphorylation, dimerization, and nuclear translocation. However, the mechanism involved in its nuclear translocation remains unclear. A previous study demonstrated that STAT3 with Arg-214/215 mutations in the coiled-coil domain (R214A/R215A; STAT3 RA) failed to undergo nuclear translocation. Here, we re-examined the nature of the STAT3 RA mutant and found that it showed higher and more extensive tyrosine-phosphorylation as well as much higher STAT3 transcriptional activity in response to stimuli. Furthermore, STAT3 RA showed nuclear translocation and faster nuclear export than wild-type STAT3 after stimulation. Moreover, nuclear retention of STAT3 RA by a chromosomal region maintenance 1 (CRM1) inhibitor, leptomycin B, decreased the enhanced STAT3 activation by stimuli. These data demonstrate that Arg-214/215 are involved in CRM1-mediated STAT3 nuclear export and the regulation of STAT3 activity.

Active Transport, Cell Nucleus↗

PubMed2005

Synthesis of functionalized asymmetric star polymers containing conductive polyacetylene segments by living anionic polymerization.

Novel 3-arm ABC, 4-arm ABCD, and 5-arm ABCDE asymmetric star polymers comprising the conductive polyacetylene precursor, poly(4-methylphenyl vinyl sulfoxide) (PMePVSO), and other segments, such as polystyrene, poly(alpha-methylstyrene), poly(4-methoxystyrene), poly(4-trimethylsilylstyrene), and poly(4-methylstyrene), were synthesized by the methodology based on living anionic polymerization using DPE-functionalized polymers. This methodology involves the addition reaction of a DPE-functionalized polymer to a living anionic polymer followed by the living anionic polymerization of MePVSO initiated from the in situ formed polymer anion with two, three, or four polymer segments. The resultant asymmetric star polymers possessed predetermined molecular weights, narrow molecular weight distributions (Mw/Mn < 1.03), and desired compositions as confirmed by SEC, 1H NMR, SLS, and elemental analysis. After thermal treatment, the PMePVSO segment in the star polymer could be completely converted into a conductive polyacetylene segment, evident from TGA and elemental analysis. These asymmetric star polymers are expected to exhibit interesting solution properties and unique microphase-separated morphological suprastructures with potential applications in nanoscopic conductive materials. Moreover, this methodology can afford the target asymmetric star polymers with arm segments varying in a wide range and enables the synthesis of more complex macromolecular architectures.

Acetylene↗

PubMed2005

Physical and functional interactions between STAT3 and ZIP kinase.

Signal transducer and activator of transcription 3 (STAT3) is a latent cytoplasmic transcription factor that can be activated by cytokines and growth factors. It plays important roles in cell growth, apoptosis and cell transformation, and is constitutively active in a variety of tumor cells. In this study, we provide evidence that zipper-interacting protein kinase (ZIPK) interacts physically with STAT3. ZIPK specifically interacted with STAT3, and did not bind to STAT1, STAT4, STAT5a, STAT5b or STAT6. ZIPK phosphorylated STAT3 on serine 727 (Ser727) and enhanced STAT3 transcriptional activity. Small interfering RNA-mediated reduction of ZIPK expression decreased leukemia inhibitory factor (LIF)- and IL-6-induced STAT3-dependent transcription. Furthermore, LIF- and IL-6-mediated STAT3 activation stimulated ZIPK activity. Taken together, our data suggest that ZIPK interacts with STAT3 within the nucleus to regulate the transcriptional activity of STAT3 via phosphorylation of Ser727.

Apoptosis Regulatory Proteins↗

PubMed2005

Roles for lysine residues of the MH2 domain of Smad3 in transforming growth factor-beta signaling.

Sma and MAD-related protein 3 (Smad3) plays a key role in the intracellular signaling of the transforming growth factor-beta (TGF-beta) family of growth factors, which exhibits a diverse set of cellular responses, including cell proliferation and differentiation. Smad3 has the N-terminal Mad homology (MH) 1 and the C-terminal MH2 domains. MH2 domain is essential for the TGF-beta-induced transcriptional activation, because the MH2 domain of Smad3 is involved in the interactions with several transcriptional cofactors as well as the type I TGF-beta receptor (TbetaR-I). In this study, we examined the roles for four lysine residues (Lys-333, Lys-341, Lys-378, and Lys-409) in the Smad3 MH2 domain. Mutation of the lysine (K)-378 to arginine (R) (K378R) abolished the interaction with TbetaR-I, phosphorylation, transcriptional activation by an active TbetaR-I. The K341R mutant also failed to stimulate TGF-beta-induced transcription by resting in the cytoplasm. However, the K409R mutant showed a higher transcriptional activity by stronger interactions with co-activators, such as p300/CBP. Furthermore, both the K341R and K378R mutants act as dominant-negative inhibitors in the TGF-beta-induced target genes of endogenous TGF-beta signal. Thus, the lysine residues of Smad3 MH2 domain play important roles in the transcriptional regulation of TGF-beta signals through TbetaR-I.

Amino Acid Sequence↗

PubMed2005

Methylenetetrahydrofolate reductase gene polymorphisms in patients with cerebral hemorrhage.

Elevated plasma total homocysteine (HCY) level is a risk factor for coronary heart disease and ischemic stroke. We investigated relationships between polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene, and plasma levels of HCY and folate in patients of Mongolian races who suffered from cerebral ischemia (CI, n = 42) or cerebral hemorrhage (CH, n = 20) and in the 24 age-matched controls. The incidences of both homozygous and heterozygous MTHFR gene mutations in CI (26 and 43%) and in CH (25 and 60%) were significantly higher than those in the controls (8 and 25%). Homozygous MTHFR gene mutation was associated with reduced plasma folate levels, but not with increased plasma HCY levels. Among the subjects with homozygous MTHFR gene mutation, plasma folate levels in CH was significantly lower than those in CI and controls. MTHFR gene mutation in CH was found to be as common as that in CI and was associated with reduced plasma folate levels in the both. In homozygous MTHFR gene mutation, the plasma folate level was profoundly reduced in CH as compared with CI and controls, suggesting that subjects with low plasma folate levels have a predisposition to intracerebral bleeding.

Aged↗

PubMed2005

In vivo characterization of bone marrow-derived fibroblasts recruited into fibrotic lesions.

Fibroblasts, which are widely distributed and play a key part in tissue fibrosis, are phenotypically and functionally heterogeneous. Recent studies reported that bone marrow can be a source of tissue fibroblast. In the study reported here, we investigated in vivo characterization of bone marrow-derived fibroblasts recruited into various fibrotic lesions. Mice were engrafted with bone marrow isolated from transgenic mice expressing green fluorescent protein (GFP), and fibrotic lesions were induced by cancer implantation (skin), excisional wounding (skin), and bleomycin administration (lung). A small population of GFP+ fibroblast was found even in nonfibrotic skin (8.7% +/- 4.6%) and lung (8.9% +/- 2.5%). The proportion of GFP+ fibroblasts was significantly increased after cancer implantation(59.7% +/- 16.3%) and excisional wounding (32.2% +/- 4.8%), whereas it was not elevated after bleomycin administration (7.1% +/- 2.4%). Almost all GFP+ fibroblasts in fibrotic lesions expressed type I collagen, suggesting that bone marrow-derived fibroblasts would contribute to tissue fibrosis. GFP+ fibroblasts expressed CD45, Thy-1, and alpha-smooth muscle actin at various proportions. Our results suggested that bone marrow-derived fibroblasts expressed several fibroblastic markers in vivo and could be efficiently recruited into fibrotic lesions in response to injurious stimuli; however, the degree of recruitment frequency might depend on the tissue microenvironment.

Animals↗

PubMed2004

Physical and functional interactions between STAP-2/BKS and STAT5.

Signal-transducing adaptor protein family of proteins (STAPs), which currently contains two members, are proposed to be adaptor molecules because of their pleckstrin homology (PH) and Src-homology 2 (SH2)-like domains. STAP-1 has been shown to interact with STAT5 and the tyrosine kinase Tec. With regard to STAP-2/BKS functions, immunoprecipitation experiments and intracellular stainings revealed STAP-2/BKS binds STAT5 in several types of cells. Mutational studies revealed that the PH- and SH2-like domains of STAP-2/BKS interacted with the C-terminal region of STAT5. STAP-2/BKS and STAT5 were found to constitutively co-localize in the cytoplasm of resting cells, but STAP-2/BKS was found to dissociate upon STAT5 phosphorylation, suggesting a role in regulating signaling of STAT5. The physiological role of these interactions is not fully understood, but in studies of overexpression of STAP-2/BKS, cytokine-induced tyrosine phosphorylation and transcriptional activation of STAT5 was diminished. In addition, thymocytes from STAP-2/BKS-deficient mice showed the enhanced interleukin-2-dependent cell growth. Taken together, STAP-2/BKS is an additional modulator of STAT5-mediated signaling.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Surface hydrophobicity of fluorinated block copolymers enhanced by supercritical carbon dioxide annealing.

Supercritical carbon dioxide (scCO2) annealing enhances the hydrophobicity of the surfaces of asymmetric perfluorinated block copolymers. X-ray photoelectron spectroscopy (XPS) and contact angle measurement reveal that the surface domains of the fluorinated block (PF) of poly[styrene-block-4-(perfluorooctylpropyloxy)styrene] (PS-PF) become thicker than those annealed in a vacuum. Consequently, the contact angles of water on the surfaces of PS-PF block copolymers significantly increase after the scCO2 annealing compared to those annealed in a vacuum. The surface hydrophobicity enhanced by the scCO2 annealing is related to the thickness of the surface PF domain and the conformation of the PF block.

Journal Article↗

PubMed2004

The RING domain of PIASy is involved in the suppression of bone morphogenetic protein-signaling pathway.

Bone morphogenetic proteins (BMPs) play central roles in differentiation, development, and physiologic tissue remodeling. Recently, we have demonstrated that a protein inhibitor of activated STAT, PIASy, suppresses TGF-beta signaling by interacting with Sma and MAD-related protein 3 (Smad3). In this study, we examined a PIASy-dependent inhibitory effect on BMP signaling. PIASy expression was induced by BMP-2 stimulation and suppressed BMP-2-dependent Smad activity in hepatoma cells. Furthermore, BMP-2-regulated Smads directly bound to PIASy. We also demonstrated that the RING domain of PIASy played an important role in PIASy-mediated suppression of Smad activity. We here provide evidence that the inhibitory action of PIASy on BMP-regulated Smad activity was due to direct physical interactions between Smads and PIASy through its RING domain.

Blotting, Northern↗

PubMed2004

Physical and functional interactions between Daxx and TSG101.

Daxx has been reported to mediate the Fas/JNK-dependent signals in the cytoplasm. However, several evidences have suggested that Daxx is located mainly in the nucleus and functions as a transcriptional regulator. Recently, we identified DMAP1, a TSG101-interacting protein as a Daxx binding partner by yeast two-hybrid screening. TSG101 has been shown to act as transcriptional co-repressor of nuclear hormone receptors. Here we examined whether TSG101also interacts with Daxx directly. The association of Daxx and TSG101 was confirmed using co-expressed tagged proteins. The interaction regions in both proteins were also mapped, and the cellular localization of the interaction was examined. TSG101 formed a complex with Daxx through its coiled-coil domain and co-localized in the nucleus. Furthermore, TSG101 enhanced Daxx-mediated repression of glucocorticoid receptor transcriptional activity. These results provide the novel molecular interactions between Daxx and TSG101, which establish an efficient repressive transcription complex in the nucleus.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Physical and functional interactions between Daxx and DNA methyltransferase 1-associated protein, DMAP1.

Daxx has been shown to play an essential role in type I IFN-alphabeta-mediated suppression of B cell development and apoptosis. Recently, we demonstrated that Tyk2 is directly involved in IFN signaling for the induction and translocation of Daxx, which may result in growth arrest and/or apoptosis of B lymphocyte progenitors. To clarify how Daxx regulates B cell development, we examined Daxx interacting partners by yeast two-hybrid screening. DNA methyltransferase 1 (DNMT1)-associated protein (DMAP1) was identified and demonstrated to interact with Daxx. The interaction regions in both proteins were mapped, and the cellular localization of the interaction was examined. Both Daxx and DMAP1 formed a complex with DNMT1 and colocalized in the nucleus. DMAP1 enhanced Daxx-mediated repression of glucocorticoid receptor transcriptional activity. Furthermore, Daxx protected protein degradation of DMAP1 in vivo. These results provide the novel molecular link between Daxx and DNMT1, which establishes a repressive transcription complex in the nucleus.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Nuclear MxA proteins form a complex with influenza virus NP and inhibit the transcription of the engineered influenza virus genome.

Mx proteins belong to the dynamin superfamily of high molecular weight GTPases and interfere with multiplication of a wide variety of viruses. Earlier studies show that nuclear mouse Mx1 and human MxA designed to be localized in the nucleus inhibit the transcription step of the influenza virus genome. Here we set a transient influenza virus transcription system using luciferase as a reporter gene and cells expressing the three RNA polymerase subunits, PB1, PB2 and PA, and NP. We used this reporter assay system and nuclear-localized MxA proteins to get clues for elucidating the anti-influenza virus activity of MxA. Nuclear-localized VP16-MxA and MxA-TAg NLS strongly interfered with the influenza virus transcription. Over-expression of PB2 led to a slight resumption of the transcription inhibition by nuclear MxA, whereas over-expression of PB1 and PA did not affect the MxA activity. Of interest is that the inhibitory activity of the nuclear MxA was markedly neutralized by over-expression of NP. An NP devoid of its C-terminal region, but containing the N-terminal RNA binding domain, also neutralized the VP16-MxA activity in a dose-dependent manner, whereas an NP lacking the N-terminal region did not affect the VP16-MxA activity. Further, not only VP16-MxA but also the wild-type MxA was found to interact with NP in influenza virus-infected cells. This indicates that the nuclear MxA suppresses the influenza virus transcription by interacting with not only PB2 but also NP.

Animals↗