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991.
Sugawara A Torigoe T Tamura Y Kamiguchi K Nemoto K Oguro H Sato N 《Cell stress & chaperones》2009,14(2):133-139
Polyamine compound deoxyspergualin (DSG) is a potent immunosuppressive agent that has been applied clinically for protecting
graft rejection and treatment of Wegener's granulomatosis. Though DSG can bind to heat-shock proteins (HSPs) in cells, its
mechanism of immunosuppressive action remains unknown. It is widely accepted that extracellular HSPs are capable of stimulating
dendritic cells (DC) through cell surface receptors, leading to DC activation and cytokine release. In this study, we examined
if DSG analogs could inhibit HSP70-induced DC activation. Bone marrow derived immature mouse DCs and peripheral blood mononuclear
cell-derived immature human DCs were generated and incubated with Alexa 488-labeled Hsp70 in the presence of methoxyDSG (Gus-1)
that had comparable HSP70-binding affinity to DSG or DSG analog GUS-7, which had much more reduced binding affinity for HSP70.
The binding of HSP70 to immature DCs was analyzed by laser microscopy and flow cytometry. HSP70-induced DC activation was
assessed by TNF-α release by enzyme-linked immunosorbent assay. Binding of Hsp70 to the cell surface of immature DCs was inhibited
under the presence of Gus-1, but not under the presence of Gus-7. Immature DCs were activated and released TNF-α by the stimulation
with HSP70 for 12 hours; however, the HSP70-induced TNF-α release was suppressed under the presence of Gus-1, and partially
suppressed under the presence of Gus-7. Similar results were observed when immature human DCs were stimulated under the same
conditions. Immunosuppressive mechanism of DSG may be explained, at least in part, by the inhibition of extracellular HSP70-DC
interaction and HSP70-induced activation of immature DCs.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
992.
Ryuji Yonekura Hiroki Yamanaka Atushi Ushimaru Kazuaki Matsui Kimiko Uchii Atsushi Maruyama 《Biological invasions》2009,11(6):1347-1355
Asymmetry in the competition abilities between invasive and native consumers can potentially influence the colonization success
by invasive species. We tested whether a subsidy of allochthonous prey enhanced an asymmetric competition between invasive
bluegill (Lepomis macrochirus) and two native cyprinid fish, that is, stone moroko (Pseudorasbora parva) and tamoroko (Gnathopogon elongatus elongatus). A field experiment was conducted using enclosures wherein the strength of interspecific competition and the presence/absence
of allochthonous prey were manipulated. The experiment revealed that allochthonous prey alleviated the limitation of fish
growths caused by a severe competition for aquatic prey resources. However, the importance of allochthonous prey differed
considerably between invasive bluegill and the two native cyprinids. Individual bluegills grew faster when the allochthonous
prey was supplied, whereas no difference in growth was observed in the two cyprinids whether or not allochthonous prey was
supplied. Interestingly, the importance of allochthonous prey on the total amount of bluegill growth varied depending on the
numerical abundance of native cyprinid competitors, and this importance increased when the native cyprinids were abundant.
These findings indicated that allochthonous prey provides an asymmetric growth benefit to invasive bluegills over the two
native cyprinids by alleviating asymmetrically the competition strength in a Japanese pond, especially under the conditions
of severe interspecific resource competition and a limitation in the utilization of in situ prey resources. 相似文献
993.
Yoshihiko Tsukada Atsushi Suetsugu Yosuke Osawa Hisataka Moriwaki 《Biochemical and biophysical research communications》2009,381(4):733-4088
Engelbreth-Holm-Swarm (EHS) gel has been reported to maintain the mature hepatocyte phenotypes in primary cultured hepatocytes. We investigated the effect of EHS gel on the differentiation of fetal liver cells, which contain stem/progenitor cells. The isolated fetal liver cells cultured on EHS gel formed a spherical shape and increased liver-specific gene expressions compared with cells cultured on collagen. The hepatic progenitor cells that were transplanted subcutaneously to BALB/c nude mice could survive and express hepatocyte marker alpha-fetoprotein when the cells were suspended with EHS gel. These findings demonstrate that EHS gel supports cytodifferentiation from immature progenitor cells to hepatocytes and maintain its differentiated phenotypes in vitro and in vivo. 相似文献
994.
Shiori Kohno Yoshimi Nakano Moe Ishii Atsushi Baba 《Biochemical and biophysical research communications》2009,380(1):93-35256
Reelin is a secreted glycoprotein essential for normal brain development and function. In the extracellular milieu, Reelin is subject to specific cleavage at two (N-t and C-t) sites. The N-t cleavage of Reelin is implicated in psychiatric and Alzheimer’s diseases, but the molecular mechanism and physiological significance of this cleavage are not completely understood. Particularly, whether the N-t cleavage affects the signaling activity of Reelin remains controversial.Here, we show that the protease in charge of the N-t cleavage of Reelin requires the activity of certain proprotein convertase family for maturation and has strong affinity for heparin. By taking advantage of these observations, we for the first time succeeded in obtaining “Uncleaved” and “Completely Cleaved” Reelin proteins. The N-t cleavage splits Reelin into two distinct fragments and virtually abolishes its signaling activity. These findings provide an important biochemical basis for the function of Reelin proteolysis in brain development and function. 相似文献
995.
Satoshi Arai Asuka Shiokawa Yoshimi Kakinuma Mitsutoshi Toyama Mikako Shirouzu So Iwata Takeshi Murata 《Biochemical and biophysical research communications》2009,390(3):698-19960
Enterococcus hirae vacuolar ATPase (V-ATPase) is composed of a soluble catalytic domain (V1; NtpA3-B3-D-G) and an integral membrane domain (V0; NtpI-K10) connected by a central and peripheral stalk(s) (NtpC and NtpE-F). Here we examined the nucleotide binding of NtpA monomer, NtpB monomer or NtpD-G heterodimer purified by using Escherichia coli expression system in vivo or in vitro, and the reconstitution of the V1 portion with these polypeptides. The affinity of nucleotide binding to NtpA was 6.6 μM for ADP or 3.1 μM for ATP, while NtpB or NtpD-G did not show any binding. The NtpA and NtpB monomers assembled into NtpA3-B3 heterohexamer in nucleotide binding-dependent manner. NtpD-G bound NtpA3-B3 forming V1 (NtpA3-B3-D-G) complex independent of nucleotides. The V1 formation from individual NtpA and NtpB monomers with NtpD-G heterodimer was absolutely dependent on nucleotides. The ATPase activity of reconstituted V1 complex was as high as that of native V1-ATPase purified from the V0V1 complex by EDTA treatment of cell membrane. This in vitro reconstitution system of E. hirae V1 complex will be valuable for characterizing the subunit-subunit interactions and assembly mechanism of the V1-ATPase complex. 相似文献
996.
Xiaoxiang Liu Motonori Hashimoto Atsushi Yamaguchi Toshihide Yamashita 《Biochemical and biophysical research communications》2009,382(4):795-18400
Neuronal axons are guided by attractive and repulsive cues in their local environment. Since the identification of the repulsive guidance molecule (RGM) a (RGMa) as an axon repellent in the visual system, diverse functions, as part of the developing and adult central nervous system (CNS), have been ascribed to it. The binding of RGMa to its receptor neogenin has been shown to induce RhoA activation, leading to inhibitory/repulsive behavior and the collapse of the neuronal growth cone. In this paper, we provide evidence to suggest the involvement of RGMb, another member of the RGM family, in the rat CNS. RGMb inhibits neurite outgrowth in postnatal cerebellar granule neurons (CGNs) in vitro. RGMb is expressed by oligodendrocytes and neurons in the adult rat CNS, and the expression of this molecule is upregulated around the site of spinal cord injury. RGMb is present in myelin isolated from an adult rat brain. RGMb and neogenin are coexpressed in CGNs and entorhinal cortex neurons. These findings suggest that RGMb is a myelin-derived inhibitor of axon growth in the CNS. Inhibition of RGMb may provide an alternative approach for the treatment of spinal injuries. 相似文献
997.
998.
999.
Atsushi Intoh Akira Kurisaki Dr. Yuko Yamanaka Hisashi Hirano Hiroyuki Fukuda Hiromu Sugino Makoto Asashima Professor 《Proteomics》2009,9(1):126-137
Embryonic stem cells (ESCs) are established from the inner cell mass of preimplantation embryos, are capable of self‐renewal, and exhibit pluripotency. Given these unique properties, ESCs are expected to have therapeutic potential in regenerative medicine and as a powerful tool for in vitro differentiation studies of stem cells. Various growth factors and extracellular matrix components regulate the pluripotency and differentiation of ESC progenies. Thus, the cell surface receptors that bind these regulatory factors are crucial for the precise regulation of stem cells. To identify membrane proteins that are involved in the regulation of pluripotent stem cells, the membrane proteins of murine ESCs cultured with or without leukemia inhibitory factor (LIF) were purified and analyzed by quantitative proteomics. 2‐D PAGE‐based analysis using fluorescently labeled proteins and shotgun‐based analysis with isotope‐labeled peptides identified 338 proteins, including transmembrane, membrane‐binding, and extracellular proteins, which were expressed specifically in pluripotent or differentiated murine ESCs. Functions of the identified proteins revealed cell adhesion molecules, channels, and receptors, which are expected to play important roles in the maintenance of murine ESC pluripotency. Membrane proteins that are expressed in pluripotent ESCs but not in differentiated cells such as Slc16a1 and Bsg could be useful for the selection of the stem cells in vitro. 相似文献
1000.
Akihiro Tazumi Yuki Kakinuma Naoaki Misawa John E Moore Beverley C Millar Motoo Matsuda 《BMC microbiology》2009,9(1):256