Publications by authors named "Mikio Niwa"

7 Publications

  • Page 1 of 1

Secretion of signal peptides via extracellular vesicles.

Biochem Biophys Res Commun 2021 Jun 5;560:21-26. Epub 2021 May 5.

Department of Brain Function, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, 464-8601, Japan; Department of Molecular Pharmacokinetics, Nagoya University Graduate School of Medicine, Nagoya, Aichi, 464-8601, Japan.

Signal peptides (SPs) consist of short peptide sequences present at the N-terminal of newly synthesizing proteins and act as a zip code for the translocation of the proteins to the endoplasmic reticulum (ER). It was thought that the SPs are intracellularly degraded after translocation to the ER; however, recent studies showed cleaved SPs have diverse roles for controlling cell functions in auto- and/or intercellular manners. In addition, it still remains obscure how SP fragments translocate away from the site where they are produced. Extracellular vesicles (EV) are important for intercellular communication and can transport functional molecules to specific cells. In this study, we show that SPs are involved in EV from T-REx AspALP cells that were transfected with a human APP SP-inducible expression vector. There was no difference in the average particle size or particle concentration of EV collected from T-REx AspALP cells and T-REx Mock cells. When the SP content in the EV was examined by mass spectrometry, the C-terminal fragment of APP SP was identified in the exosomes (SEV) of T-REx AspALP cells. In our preparation of SEV fractions, no ER-specific proteins were detected; therefore, SPs may be included in SEV but not in the debris of degraded ER. This is the first indication that SPs are secreted from cells via EV.
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http://dx.doi.org/10.1016/j.bbrc.2021.04.073DOI Listing
June 2021

Clinical Features and Pathogenic Mechanisms of Gastrointestinal Injury in COVID-19.

J Clin Med 2020 Nov 11;9(11). Epub 2020 Nov 11.

Yakult Central Institute for Microbiological Research, Kunitachi, Tokyo 186-0011, Japan.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of the global coronavirus disease 2019 (COVID-19) outbreak. Along with the respiratory tract, the gastrointestinal (GI) tract is one of the main extra-pulmonary targets of SARS-CoV-2 with respect to symptom occurrence and is a potential route for virus transmission, most likely due to the presence of angiotensin-converting enzyme 2. Therefore, understanding the mechanisms of GI injury is crucial for a harmonized therapeutic strategy against COVID-19. This review summarizes the current evidence for the clinical features of and possible pathogenic mechanisms leading to GI injury in COVID-19.
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http://dx.doi.org/10.3390/jcm9113630DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7696882PMC
November 2020

Antibody markers in the diagnosis of inflammatory bowel disease.

World J Gastroenterol 2016 Jan;22(3):1304-10

Keiichi Mitsuyama, Inflammatory Bowel Disease Center, Kurume University School of Medicine, Kurume 830-0011, Japan.

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a chronic intestinal inflammation of unknown etiology. The diagnosis of IBD is based on endoscopic, radiologic and histopathologic criteria. Recently, the search for a noninvasive marker that could augment or replace part of this diagnostic process has become a focus of IBD research. In this review, antibody markers, including microbial antibodies, autoantibodies and peptide antibodies, will be described, focusing on their common features. At present, no single marker with qualities that are satisfactory for the diagnosis and treatment of IBD has been identified, although panels of some antibodies are being evaluated with keen interest. The discovery of novel IBD-specific and sensitive markers is anticipated. Such markers could minimize the use of endoscopic and radiologic examinations and could enable clinicians to implement individualized treatment plans designed to improve the long-term prognosis of patients with IBD.
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http://dx.doi.org/10.3748/wjg.v22.i3.1304DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4716040PMC
January 2016

Possible diagnostic role of antibodies to Crohn's disease peptide (ACP): results of a multicenter study in a Japanese cohort.

J Gastroenterol 2014 Apr 3;49(4):683-91. Epub 2013 Dec 3.

Inflammatory Bowel Disease Center, Division of Gastroenterology, Department of Medicine, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830-0011, Japan,

Background: Various noninvasive tests have been studied to screen for patients with Crohn's disease (CD), and were found to have limited accuracy and sensitivity, particularly in Asian populations. The aim of our study was to explore the possible diagnostic utility of antibodies to the CD peptide (ACP) in patients with CD.

Methods: In a multicenter study using enzyme-linked immunosorbent assay, serum ACP levels were determined in 196 patients with CD, 210 with ulcerative colitis, 98 with other intestinal diseases, 132 with other inflammatory diseases, and 183 healthy controls. and then examined for correlation to clinical variables. The diagnostic utility of ACP was evaluated by receiver operating characteristics analysis and compared with anti-Saccharomyces cerevisiae antibodies (ASCA).

Results: ACP levels were significantly elevated in the CD patients, but not in the other groups that included UC, other intestinal diseases, other inflammatory diseases and the healthy controls. Among these other groups, ACP levels were not significantly different. In the CD patients, ACP had a higher sensitivity and specificity (63.3 and 91.0 %, respectively) than ASCA (47.4 and 90.4 %). ACP levels were negatively associated with disease duration, but not with CDAI, disease location, or medical treatment.

Conclusions: ACP, a newly proposed serologic marker, was significantly associated with CD and was highly diagnostic. Further investigation is needed across multiple populations of patients and ethnic groups, and more importantly, in prospective studies.
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http://dx.doi.org/10.1007/s00535-013-0916-9DOI Listing
April 2014

Nucleolar localization signals of LIM kinase 2 function as a cell-penetrating peptide.

Protein Pept Lett 2010 Dec;17(12):1480-8

Institute for Advanced Sciences, Toagosei Co., Ltd., Tsukuba 300-2611, Japan.

LIM Kinase 2 (LIMK2) is a LIM domain-containing protein kinase which regulates actin polymerization thorough phosphorylation of the actin depolymerizing factor cofilin. It is also known to function as a shuttle between the cytoplasm and nucleus in endothelial cells. A basic amino acid-rich motif in LIMK2 was previously identified to be responsible for this shuttling function, as a nucleolar localization signal (NoLS). Here it is shown that this nucleolar localization signal sequence also has the characteristic function of a cell-penetrating peptide (CPP). We synthesized LIMK2 NoLS-conjugated peptides and a protein and analyzed their cell-penetrating abilities in various types of cells. The BC-box motif of the Von Hippel-Lindau (VHL) protein was used for the peptide. This motif previously has been reported to be involved in the neural differentiation of bone marrow stromal cells and skin-derived precursor cells. Green fluorescence protein (GFP) was used as a large biologically active biomolecule for the protein. The LIMK2 NoLS-conjugated peptides and protein translocated across the cell membranes of fibroblast cells, neural stem cells, and even iPS cells. These results suggest that LIMK2 NoLS acts as a cell-penetrating peptide and its cell-penetrating ability is not restricted by cell type. Moreover, from an in vivo assay using a mouse brain, it was confirmed that NoLS has potential for transporting biomolecules across the blood-brain barrier.
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http://dx.doi.org/10.2174/0929866511009011480DOI Listing
December 2010

Efficient isolation of cDNA clones encoding rheumatoid arthritis autoantigens by lambda phage surface display.

J Biotechnol 2004 Oct;114(1-2):55-8

Tsukuba Research Laboratory, Toagosei Co. Ltd., 2 Ohkubo, Tsukuba, Ibaraki 300-2611, Japan.

Bacteriophage lambda surface display was used to isolate cDNA clones encoding autoantigens recognized by synovial fluid (SF) or sera from patients with rheumatoid arthritis (RA). We constructed cDNA libraries from human synovial sarcoma cells and synovial tissue, using the surface display vector lambdafoo. The cDNA libraries were screened by affinity selection using 40 SF and 44 sera as probes separately immobilized in microtiter wells. Phage clones isolated encode 13 different autoantigens; an unknown protein, two proteins previously unanalyzed as autoimmune antigens, three proteins previously unknown to be recognized by RA sera, and seven known RA antigens. When analyzed their sensitivity and specificity for RA by phage enzyme-linked immunosorbent assay, frequencies of sera that recognize the newly-isolated autoantigens ranged from 20.5 to 6.8% of a panel of RA sera, and 13.6-0% of other autoimmune disease sera. These results indicate that the lambda phage surface display may be powerful for the isolation of cDNA clones encoding autoantigens recognized by SF or sera from patients with not only RA but also other autoimmune diseases.
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http://dx.doi.org/10.1016/j.jbiotec.2004.05.010DOI Listing
October 2004

CD147 and matrix metalloproteinase-2 protein expression as significant prognostic factors in esophageal squamous cell carcinoma.

Cancer 2004 Nov;101(9):1994-2000

Department of Surgery, Jikei University School of Medicine, Tokyo, Japan.

Background: The authors investigated whether the presence of matrix metalloproteinase-2 (MMP-2) and its inducer, CD147, in cancerous esophageal lesions and surrounding tissue might help to predict patient prognosis.

Methods: Tissue samples from 101 patients with esophageal squamous cell carcinoma were stained with anti-CD147 and anti-MMP-2 antibodies for immunohistochemical analysis.

Results: CD147 was expressed in cancerous and dysplastic lesions, but not in normal tissue. In contrast, MMP-2 was detected mainly in normal interstitial tissue adjacent to cancerous lesions, but it was detected also in cancerous lesions in some patients. Pathologic findings demonstrated that the intensity of MMP-2 staining in normal tissue was associated positively with the depth of tumor infiltration and the stage of disease, whereas MMP-2 staining in cancerous tissue was associated positively with vascular and lymphatic vessel invasion as well as with immature differentiation of cancer cells. Using a proportional hazard model, including information on CD147 staining patterns within cancerous lesions along with clinical cancer staging, improved the accuracy of predicting patient prognosis.

Conclusions: These results suggested that measurement of CD147 and MMP-2 expression with simple immunohistochemical staining may enhance further the understanding of the pathophysiology of invading tumor cells and, when used in combination with cancer staging, may increase the ability of investigators to predict prognosis in patients with esophageal squamous cell carcinoma.
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http://dx.doi.org/10.1002/cncr.20593DOI Listing
November 2004