Nanki T.,Toho University |
Imai T.,KAN Research Institute Inc |
Kawai S.,Toho University
Modern Rheumatology | Year: 2016
Fractalkine is a CX3C chemokine that exists in both membrane-bound and soluble forms. Interaction between fractalkine and its unique receptor (CX3CR1) induces cell adhesion, chemotaxis, crawling, “accessory cell” activity, and survival. The serum level of fractalkine is elevated in patients with rheumatoid arthritis (RA) and is correlated with disease activity. Peripheral blood CD16+ monocytes and a subset of T cells express CX3CR1, while fractalkine is expressed on fibroblast-like synoviocytes and endothelial cells in the synovial tissue of patients with RA. Fractalkine expression is enhanced by tumor necrosis factor-α and interferon-γ, and it promotes the migration of monocytes, T cells, and osteoclast precursors into RA synovial tissue. Fractalkine also induces the production of inflammatory mediators by macrophages, T cells, and fibroblast-like synoviocytes. Moreover, fractalkine promotes angiogenesis and osteoclastogenesis. In an animal model of RA, arthritis was improved by the abrogation of fractalkine. Recently, a clinical trial of an anti-fractalkine monoclonal antibody for the treatment of RA commenced in Japan. We review the multiple roles of fractalkine in the pathogenesis of RA and its potential as a therapeutic target for this disease. © 2016 Japan College of Rheumatology
Hoshino A.,Tokyo Medical and Dental University |
Hoshino A.,National Health Research Institute |
Hoshino A.,Nagoya University |
Ueha S.,University of Tokyo |
And 8 more authors.
Journal of Cell Science | Year: 2013
Chemokines have recently been reported to be involved in pathological bone destruction. However, the physiological roles of chemokines in bone metabolism in vivo have not been well documented. We analyzed the bone phenotypes in Cx3cr1-deficient mice. The mice exhibited slight but significant increases in trabecular and cortical thickness, reduced numbers of osteoclasts and increased rates of osteoid formation. Although the morphometric parameters showed marginal differences, the Cx3cr1-deficient bones showed an elevated expression of Osterix/SP7, which encodes an essential transcriptional factor for osteoblasts, whereas the gene Osteocalcin/Bglap, which encodes a late marker, was downregulated. The levels of transcripts for various osteoclastic markers, such as receptor activator of NF-κB (RANK)/TNFRSF11A, receptor activator of NF-kB ligand (RANKL)/TNFSF11, tartrate-resistant acid phosphatase 5b (TRAP5B)/ACP5B, Cathepsin K(CTSK), MMP3 and MMP13, were significantly decreased in the Cx3cr1-deficient bones. Cultured Cx3cr1-deficient osteoblastic cells showed inverse temporal patterns of osteoblastic marker expression and reduced calcium deposition. Furthermore, in vitro studies and immunofluorescence staining against CX3CR1 and CX3CL1 suggested a role for the CX3CR1-CX3CL1 axis in an early stage of osteoblast differentiation, possibly through their trans and cis interactions. Cultured Cx3cr1-deficient pre-osteoclasts showed impaired differentiation, mainly due to a deficiency of the CD115+ CD11blo osteoclastogenic population ofmyeloid-lineage precursors. The treatment of bone-marrow-derived osteoclastic cultures with recombinant CX3CL1 at different time points suggested that the CX3CR1-CX3CL1 axis favors the maintenance of osteoclastic precursors, but not differentiated osteoclasts. These observations uncovered novel roles of the CX3CR1-CX3CL1 axis in the differentiation of both osteoblasts and osteoclasts. © 2013. Published by The Company of Biologists Ltd.
Kawano S.,Kobe University |
Kawano S.,Eisai Co. |
Mizutani K.,Kobe University |
Miyata M.,Kobe University |
And 3 more authors.
Genes to Cells | Year: 2010
Integrin α6β4 is abundantly expressed in normal epithelial cells and forms hemidesmosomes, one of cell-extracellular matrix junctions. In many types of cancer cells, integrin α6β4 is up-regulated, laminin, an integrin α6β4-binding extracellular matrix protein, is cleaved, and hemidesmosomes are disrupted, eventually causing an enhancement of cancer cell movement and a facilitation of their invasion. It was previously shown that integrin α6β4 interacts with ErbB1 and ErbB2 and enhances cell proliferation and motility. Here we show that integrin α6β4 interacts with ErbB3 but not with ErbB1, ErbB2 or ErbB4, and enhances the heregulin-induced, ErbB3/ErbB2 heterodimer-mediated DNA synthesis, but not cell motility, in A549 cells. © 2010 The Authors. Journal compilation © 2010 by the Molecular Biology Society of Japan/Blackwell Publishing Ltd.
Hotta A.,KAN Research Institute Inc. |
Kawakatsu T.,KAN Research Institute Inc. |
Nakatani T.,KAN Research Institute Inc. |
Sato T.,Eisai Co. |
And 10 more authors.
Journal of Cell Biology | Year: 2010
LL5β has been identified as a microtubule-anchoring factor that attaches EB1/CLIP-associating protein (CLASP)-bound microtubule plus ends to the cell cortex. In this study, we show that LL5β and its homologue LL5α (LL5s) colocalize with autocrine laminin-5 and its receptors, integrins α3β1 and α6β4, at the basal side of fully polarized epithelial sheets. Depletion of both laminin receptor integrins abolishes the cortical localization of LL5s, whereas LL5 depletion reduces the amount of integrin α3 at the basal cell cortex. Activation of integrin α3 is sufficient to initiate LL5 accumulation at the cell cortex. LL5s form a complex with the cytoplasmic tails of these integrins, but their interaction might be indirect. Analysis of the three-dimensional distribution of microtubule growth by visualizing EB1-GFP in epithelial sheets in combination with RNA interference reveals that LL5s are required to maintain the density of growing microtubules selectively at the basal cortex. These findings reveal that signaling from laminin-integrin associations attaches microtubule plus ends to the epithelial basal cell cortex. © 2010 Hotta et al.
Kaieda S.,Osaka University |
Matsui C.,KAN Research Institute Inc. |
Mimori-Kiyosue Y.,RIKEN |
Ikegami T.,Osaka University
Biochemistry | Year: 2010
Elucidation of the basis of interactions between biological molecules is essential for the understanding of living systems. Src-homology 3 (SH3) domains play critical roles in interaction networks of proteins by recognizing a proline-rich sequence motif, PxxP. There are, however, several SH3 domains that specifically bind to polypeptide chains without the conventional recognition sequence. The SH3 domain of DDEF1 associates with the SAMP motifs of the adenomatous polyposis coli (APC) tumor suppressor. The SAMP motifs are indispensable for the normal function of APC in tumor suppression. Here we present the structural basis of the interaction between the DDEF1-SH3 domain and the APC-SAMP motifs. We determined the solution structures of the DDEF1-SH3 domain both in a free state and in a complex with APC-SAMP. As the affinity of the interaction was not sufficiently high for the determination of the complex structure in solution by conventional methods, we utilized a fusion protein of the DDEF1-SH3 domain and APC-SAMP. The structures revealed that the SAMP motif adopts a class II polyproline type II helix even though it does not contain the PxxP motif and that a characteristically large hydrophobic pocket of the SH3 domain confers high selectivity to the interaction. Furthermore, investigation into the backbone dynamics of the free and bound systems by NMR spin relaxation experiments demonstrated that the DDEF1-SH3 domain exhibits high flexibility at the peptide recognition site in the absence of the ligand and that most residues of the APC-SAMP motif display extensive local motions even in the stable complex. © 2010 American Chemical Society.
Muto S.,Jichi Medical University |
Hata M.,KAN Research Institute Inc. |
Taniguchi J.,Jichi Medical University |
Tsuruoka S.,Jichi Medical University |
And 9 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2010
Claudin-2 is highly expressed in tight junctions of mouse renal proximal tubules, which possess a leaky epithelium whose unique permeability properties underlie their high rate of NaCl reabsorption. To investigate the role of claudin-2 in paracellular NaCl transport in this nephron segment, we generated knockout mice lacking claudin-2 (Cldn2-/-). The Cldn2-/- mice displayed normal appearance, activity, growth, and behavior. Light microscopy revealed no gross histological abnormalities in the Cldn2 -/- kidney. Ultrathin section and freeze-fracture replica electron microscopy revealed that, similar to those of wild types, the proximal tubules of Cldn2-/- mice were characterized by poorly developed tight junctions with one or two continuous tight junction strands. In contrast, studies in isolated, perfused S2 segments of proximal tubules showed that net transepithelial reabsorption of Na+, Cl-, and water was significantly decreased in Cldn2-/- mice and that there was an increase in paracellular shunt resistance without affecting the apical or basolateral membrane resistances. Moreover, deletion of claudin-2 caused a loss of cation (Na+) selectivity and therefore relative anion (Cl -) selectivity in the proximal tubule paracellular pathway. With free access to water and food, fractional Na+ and Cl- excretions in Cldn2-/- mice were similar to those in wild types, but both were greater in Cldn2-/- mice after i.v. administration of 2% NaCl. We conclude that claudin-2 constitutes leaky and cation (Na +)-selective paracellular channels within tight junctions of mouse proximal tubules.
Nakatani T.,KAN Research Institute Inc. |
Minaki Y.,KAN Research Institute Inc. |
Minaki Y.,Kyoto University |
Kumai M.,A D Technology Inc. |
And 3 more authors.
Developmental Biology | Year: 2014
Purkinje cells (PCs) provide the primary output from the cerebellar cortex, which controls movement and posture, and loss of PCs causes severe cerebellar dysfunction. The mechanisms underlying cell fate determination and early differentiation of PC remain largely unknown. Here we show that the c-Ski family member and transcriptional regulator Corl2 is required for correct differentiation of PCs. In Corl2 knock-out embryos, initial PC specification appeared largely normal, but in a subset of presumptive PCs generated near the ventral border of the PC domain, cell fate choice was compromised and cells showed a mixed identity expressing the interneuron marker Pax2 as well. Additionally, selection and maintenance of the transmitter phenotype was compromised in most developing PCs in the mutants. During later differentiation steps, induction of PC marker genes was significantly suppressed, suggesting that maturation was delayed in the absence of Corl2. Consistently, defects in migration, cell polarization and dendrite formation were observed in mutant PCs, although their axonal trajectories appeared normal. These phenotypes closely resembled those of mutants for Rora, an essential regulator of PC differentiation. However, Rora expression was not significantly changed in the Corl2 mutants, indicating that Corl2 does not simply act upstream of Rora to promote PC differentiation. ChIP experiments revealed that Corl2 bound to the promoter regions of several PC-selective genes, which are also known to be direct downstream targets of RORα. Altogether, our results identified a novel regulatory program of PC differentiation involving Corl2, which might cooperate with the RORα pathway. © 2014 Elsevier Inc.
Kurita S.,Kobe University |
Yamada T.,KAN Research Institute Inc. |
Rikitsu E.,KAN Research Institute Inc. |
Ikeda W.,KAN Research Institute Inc. |
And 2 more authors.
Journal of Biological Chemistry | Year: 2013
Adherens junction (AJ) is a specialized cell-cell junction structure that plays a role in mechanically connecting adjacent cells to resist strong contractile forces and to maintain tissue structure, particularly in the epithelium. AJ is mainly comprised of cell adhesion molecules cadherin and nectin and their associating cytoplasmic proteins including β-catenin, α-catenin, p120ctn, and afadin. Our series of studies have revealed that nectin first forms cell-cell adhesion and then recruits cadherin to form AJ. The recruitment of cadherin by nectin is mediated by the binding of α-catenin and p120ctn to afadin. Recent studies showed that PLEKHA7 binds to p120ctn, which is associated with E-cadherin, and maintains the integrity of AJ in epithelial cells. In this study, we showed that PLEKHA7 bound to afadin in addition to p120ctn and was recruited to the nectin-3α-based cell-cell adhesion site in a manner dependent on afadin, but not on p120ctn. The binding of PLEKHA7 to afadin was required for the proper formation of AJ, but not for the formation of tight junction, in EpH4 mousemammarygland epithelial cells. These results indicate that PLEKHA7 plays a cooperative role with nectin and afadin in the proper formation of AJ in epithelial cells. © 2013 by The American Society for Biochemistry and Molecular Biology, Inc.
Nakatani T.,KAN Research Institute Inc |
Kumai M.,KAN Research Institute Inc |
Mizuhara E.,KAN Research Institute Inc |
Minaki Y.,KAN Research Institute Inc |
Ono Y.,KAN Research Institute Inc
Developmental Biology | Year: 2010
Mesencephalic dopaminergic (mesDA) neurons control movement and behavior, and their loss causes severe neurological disorders, such as Parkinson's disease. Recent studies have revealed that mesDA neurons originate from mesencephalic floor plate (FP) cells, which had been thought of as non-neurogenic organizer cells regulating regional patterning and axonal projections. Otx2 and its FP-specific downstream factor Lmx1a have been shown to be sufficient to confer neurogenic activity on FP cells and determine a mesDA fate. However, the mechanism underlying how these factors control mesDA development and how FP cells and mesDA neurons are coordinately specified are still largely unknown. In the present study, we obtained evidence that Lmx1a and Lmx1b cooperate with Foxa2 to specify mesDA neuron identity by gain-of-function approaches using transgenic mice. Lmx1a/b appeared to select a mesDA fate by suppressing red nucleus fate in the context of Foxa2-positive progenitors, at least in part, through repressing the Sim1-Lhx1 and Ngn1 pathways that inhibit proper mesDA differentiation. We also found that, in the mesencephalon, FP cell fate is primarily determined by Foxa2 with a supportive action of Lmx1a/b through repressing Nkx6.1, which inhibits FP cell differentiation. Thus, FP and mesDA identities are determined by distinct specification pathways, both of which are controlled by the same combination of transcription factors, Lmx1a/b and Foxa2, and, as a consequence, mesDA neurons are generated from mesencephalic FP cells. © 2010 Elsevier Inc.
Kohsaka S.,Hokkaido University |
Sasai K.,Hokkaido University |
Sasai K.,KAN Research Institute Inc. |
Takahashi K.,Hokkaido University |
And 5 more authors.
Biochemical and Biophysical Research Communications | Year: 2011
Oncogenic stimuli such as H-Ras induce oncogene-induced senescence (OIS) in fibroblasts to protect against transformation. Here we found that a population of the human diploid fibroblasts can escape from OIS induced by H-RasV12. We designated these OIS-escaped cells as OISEC (OIS-escaped cells). OISEC lost the expression of p16 which plays an important role for cell cycle arrest for induction of senescence, but OISEC preserved the p16 expression machinery and exhibited senescence by the treatment with hydrogen peroxide (H2O2) as stress-induced premature senescence (SIPS). OISEC did not possess anchorage-independent growth potential, and functional disruption of p53 and Rb by SV40 early region encoding large T and small t antigens, induced the aneuploidy phenotype and colony-forming potential of OISEC together with the exhibition of in vivo tumor formation. Finally, we also found that the distinctive feature of OISEC is expression of transcription factors, Oct3/4, SOX2, and Nanog which is closely related to stem-like cell features. This study highlights the presence of a cell population which escaped from OIS, and this OISEC may transform into malignant cancer cells by the additional hits of several genes in vivo. © 2011 Elsevier Inc.