Publications by authors named "Mariko Sawa"

25 Publications

  • Page 1 of 1

Preclinical validation of a potent γ-secretase modulator for Alzheimer's disease prevention.

J Exp Med 2021 Apr;218(4)

Department of Neurosciences, University of California, San Diego, La Jolla, CA.

A potent γ-secretase modulator (GSM) has been developed to circumvent problems associated with γ-secretase inhibitors (GSIs) and to potentially enable use in primary prevention of early-onset familial Alzheimer's disease (EOFAD). Unlike GSIs, GSMs do not inhibit γ-secretase activity but rather allosterically modulate γ-secretase, reducing the net production of Aβ42 and to a lesser extent Aβ40, while concomitantly augmenting production of Aβ38 and Aβ37. This GSM demonstrated robust time- and dose-dependent efficacy in acute, subchronic, and chronic studies across multiple species, including primary and secondary prevention studies in a transgenic mouse model. The GSM displayed a >40-fold safety margin in rats based on a comparison of the systemic exposure (AUC) at the no observed adverse effect level (NOAEL) to the 50% effective AUC or AUCeffective, the systemic exposure required for reducing levels of Aβ42 in rat brain by 50%.
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http://dx.doi.org/10.1084/jem.20202560DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7931646PMC
April 2021

Down syndrome.

Handb Clin Neurol 2019 ;167:321-336

Department of Neurosciences, University of California San Diego, La Jolla, CA, United States. Electronic address:

Down syndrome (DS; Trisomy 21) is the most common chromosomal disorder in humans. It has numerous associated neurologic phenotypes including intellectual disability, sleep apnea, seizures, behavioral problems, and dementia. With improved access to medical care, people with DS are living longer than ever before. As more individuals with DS reach old age, the necessity for further life span research is essential and cannot be overstated. There is currently a scarcity of information on common medical conditions encountered as individuals with DS progress into adulthood and old age. Conflicting information and uncertainty about the relative risk of dementia for adults with DS is a source of distress for the DS community that creates a major obstacle to proper evaluation and treatment. In this chapter, we discuss the salient neurologic phenotypes of DS, including Alzheimer's disease (AD), and current understanding of their biologic bases and management.
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http://dx.doi.org/10.1016/B978-0-12-804766-8.00017-0DOI Listing
April 2020

Multi-level Modulation of Light Signaling by GIGANTEA Regulates Both the Output and Pace of the Circadian Clock.

Dev Cell 2019 06 16;49(6):840-851.e8. Epub 2019 May 16.

Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA. Electronic address:

Integration of environmental signals with endogenous biological processes is essential for organisms to thrive in their natural environment. Being entrained by periodic environmental changes, the circadian clock incorporates external information to coordinate physiological processes, phasing them to the optimal time of the day and year. Here, we present a pivotal role for the clock component GIGANTEA (GI) as a genome-wide regulator of transcriptional networks mediating growth and adaptive processes in plants. We provide mechanistic details on how GI integrates endogenous timing with light signaling pathways through the global modulation of PHYTOCHROME-INTERACTING FACTORs (PIFs). Gating of the activity of these transcriptional regulators by GI directly affects a wide array of output rhythms, including photoperiodic growth. Furthermore, we uncover a role for PIFs in mediating light input to the circadian oscillator and show how their regulation by GI is required to set the pace of the clock in response to light-dark cycles.
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http://dx.doi.org/10.1016/j.devcel.2019.04.030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6597437PMC
June 2019

Rapid multiple immunofluorescent staining for the simultaneous detection of cytokeratin and vimentin in the cytology of canine tumors.

Vet Clin Pathol 2018 Jun 9;47(2):326-332. Epub 2018 Mar 9.

Laboratory of Veterinary Clinical Pathology, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan.

Background: Immunocytochemistry (ICC) is utilized as an advanced technique in veterinary cytology. In tumor diagnosis, cytokeratin and vimentin are markers used to distinguish the origin of tumor cells. Standard enzyme-based ICC has limitations in clinical use; and therefore, more convenient and reliable methods are needed.

Objectives: The purpose of this study was to develop a rapid multiple immunofluorescent (RMIF) detection method for dual cytokeratin and vimentin staining on cytology slides in dogs.

Methods: Air-dried smear samples from solid tumors and sediments of pleural effusions were prepared from dogs (n = 14) that were admitted to the Veterinary Teaching Hospital, Kagoshima University, Japan. Mouse monoclonal anti-human cytokeratin (AE1/AE3) and rabbit monoclonal anti-human vimentin (SP20) antibodies were used as primary antibodies, followed by staining with Alexa Fluor-conjugated secondary antibodies. Staining using the RMIF method was compared with enzyme-based ICC staining.

Results: Rapid multiple immunofluorescent immunostaining was clear and specific in the evaluated smears, whereas the enzyme-based ICC showed nonspecific signals. By using the RMIF staining method, epithelial cells, mesenchymal cells, and mesothelial cells could be classified on a single smear of a pleural effusion. In smears of lymph nodes with epithelial tumor metastases, the RMIF method successfully detected metastatic epithelial tumor cells.

Conclusions: The RMIF method might be a useful tool for diagnostic cytology in veterinary medicine.
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http://dx.doi.org/10.1111/vcp.12598DOI Listing
June 2018

Paraffin immunofluorescence for detection of immune complexes in renal biopsies: an efficient salvage technique for diagnosis of glomerulonephritis in dogs.

BMC Vet Res 2017 Dec 1;13(1):371. Epub 2017 Dec 1.

Laboratory of Veterinary Clinical Pathology, Joint Faculty of Veterinary Medicine, Kagoshima University, 1-21-24 Korimoto, Kagoshima, 890-0065, Japan.

Background: Renal biopsy is an essential tool for the diagnosis of proteinuric kidney diseases in dogs, and evaluation of immune complexes (IC) by immunofluorescence (IF) of frozen sections (IF-F) is required for the diagnosis of IC-mediated glomerulonephritis (ICGN). However, the use of frozen sections from renal biopsies can have limitations. The aim of this study was to develop a reliable IF method using formalin-fixed and paraffin-embedded (FFPE) sections to detect ICs in dog ICGN.

Methods: Renal biopsy specimens were obtained from dogs with protein-losing nephropathies. FFPE sections were prepared, and eight antigen retrieval pretreatment protocols were performed: digestion with trypsin, microwave (MW) heating in citrate buffer (MW-CB; pH 6.0), MW heating in Tris-EDTA buffer (MW-TEB; pH 9.0), as well as combinations of the above, and a non-treated control.

Results: A combination of trypsin for 30 min (Try-30) and MW-TEB; pH 9.0 was the most effective antigen retrieval pretreatment, with clear positive signals for IgG, IgA, IgM, and C3 detected by IF-FFPE. Granular signals, an important diagnostic indicator of ICGN, were clearly observed by both IF-F and IF-FFPE after combined pretreatment with Try-30 and MW-TEB, and IgG, IgA, IgM, and C3 signals were almost completely matched in all samples by IF-F and IF-FFPE.

Conclusion: IF-FFPE with Try-30 and MW-TEB pretreatment is a valuable technique for the diagnosis of renal diseases in dogs. This method could be an efficient tool when standard IF-F cannot be used, or does not provide useful results due to lack of glomeruli in the specimens for IF-F.
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http://dx.doi.org/10.1186/s12917-017-1287-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5709965PMC
December 2017

Dysregulation of neurotrophin signaling in the pathogenesis of Alzheimer disease and of Alzheimer disease in Down syndrome.

Free Radic Biol Med 2018 01 12;114:52-61. Epub 2017 Oct 12.

University of California, San Diego, La Jolla, CA 92093, United States. Electronic address:

Neurotrophic factors, including the members of the neurotrophin family, play important roles in the development and maintenance of the nervous system. Trophic factor signals must be transmitted over long distances from axons and dendrites to the cell bodies of neurons. A mode of signaling well suited to the challenge of robust long distance signaling is the signaling endosome. We review the biology of signaling endosomes and the "signaling endosome hypothesis". Evidence for disruption of signaling endosome function in disorders of the nervous system is also reviewed. Changes in endosome structure in Alzheimer disease (AD) and Down syndrome (DS) are present early in these disorders. Data for the APP products responsible are reviewed and the consequent changes in signaling from endosomes discussed. We conclude by pointing to the need for additional studies to explore the biology of signaling endosomes in normal neurons and to elucidate their role in the pathogenesis of neurodegeneration.
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http://dx.doi.org/10.1016/j.freeradbiomed.2017.10.341DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5748266PMC
January 2018

Acquired Fanconi syndrome in two dogs following long-term consumption of pet jerky treats in Japan: case report.

J Vet Med Sci 2017 May 1;79(5):818-821. Epub 2017 Apr 1.

Laboratory of Clinical Pathology, Joint Faculty of Veterinary Medicine, Kagoshima University, 1-21-24 Kohrimoto, Kagoshima 890-0065, Japan.

Renal Fanconi syndrome has recently been associated with the ingestion of pet jerky treats from China in mostly small breed dogs in North America, Australia and Europe. We report here about two dogs with Fanconi syndrome following pet jerky treats exposure in Japan. A mixed-breed dog and a French bulldog showed weight loss, polyuria and polydipsia. For years, the owners had been feeding large quantities of pet jerky treats containing chicken prepared in China. Diagnostics revealed glycosuria without hyperglycemia, severe aminoaciduria, and in one case also ketonuria, hypokalemia and metabolic acidosis. A diagnosis of Fanconi syndrome associated with long-term consumption of Chinese pet jerky treats was made. Both dogs recovered fully following withdrawal of the pet jerky treats and supportive care. Fanconi syndrome of dogs in association with the consumption of pet jerky treats of Chinese origin can cause a broad proximal tubular defect with glycosuria and generalized amino aciduria, and should be also considered in Asia. Jerky treats associated Fanconi syndrome can be completely reversible following withdrawal of the treats and supportive care to correct the metabolic abnormalities.
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http://dx.doi.org/10.1292/jvms.17-0043DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5447965PMC
May 2017

Rapid immunocytochemistry for the detection of cytokeratin and vimentin: assessment of its diagnostic value in neoplastic diseases of dogs.

Vet Clin Pathol 2017 Mar 10;46(1):172-178. Epub 2017 Feb 10.

Laboratory of Veterinary Clinical Pathology, Joint Faculty of Veterinary Medicine, Kagoshima University, Korimoto, Kagoshima, Japan.

Background: Immunocytochemistry (ICC) is an advanced diagnostic technique used in the field of veterinary cytology. We recently developed a rapid ICC method for the detection of cytokeratin and vimentin in dogs, which helps to determine whether tumor cells are of epithelial or nonepithelial origin. However, the diagnostic value of this rapid ICC method in neoplastic diseases of dogs has not been assessed yet.

Objectives: The aim of the present study was to assess the diagnostic accuracy of rapid ICC compared to standard immunohistochemistry (IHC).

Methods: Air-dried smear samples and formalin-fixed paraffin sections were prepared from tumors excised from dogs (n = 30). Immunosignals for cytokeratin and vimentin were detected in smear samples by rapid ICC, and in paraffin sections by standard IHC. Signals in smear samples detected by rapid ICC were compared with positive staining in paraffin sections detected by standard IHC and analyzed for statistical significance (kappa statistic).

Results: Rapid ICC detected specific immunosignals in 25/30 cases (83.3%), and nonspecific signals were detected in 5/30 cases. Statistical analysis revealed fair agreement in epithelial tumors (n = 16) with cytokeratin (κ = 0.236) and vimentin (κ = 0.294). In nonepithelial tumors (n = 14), almost perfect agreement was demonstrated with cytokeratin (κ = 0.857) and vimentin (κ = 0.857).

Conclusions: The rapid ICC method can be a useful tool for the diagnostic cytology of neoplastic tissues in dogs.
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http://dx.doi.org/10.1111/vcp.12462DOI Listing
March 2017

Degenerative myelopathy in the Collie breed: a retrospective immunohistochemical analysis of superoxide dismutase 1 in an affected Rough Collie, and a molecular epidemiological survey of the SOD1: c.118G>A mutation in Japan.

J Vet Med Sci 2017 Feb 12;79(2):375-379. Epub 2016 Dec 12.

Laboratory of Clinical Pathology, Joint Faculty of Veterinary Medicine, Kagoshima University, 1-21-24 Kohrimoto, Kagoshima 890-0065, Japan.

Canine degenerative myelopathy (DM) is an adult-onset, progressive neurodegenerative disease that occurs in multiple dog breeds. A DM-associated mutation of the canine superoxide dismutase 1 (SOD1) gene, designated as c.118G>A (p.E40K), has been implicated as one of pathogenetic determinants of the disease in many breeds, but it remains to be determined whether the c.118G>A mutation is responsible for development or progression of DM in Collies. Previously, a Rough Collie was diagnosed clinically and histopathologically as having DM in Japan, suggesting the possibility that the Collie breed may be predisposed to DM due to the high frequency of c.118G>A in Japan. In this study, accumulation and aggregate formation of SOD1 protein were retrospectively demonstrated in the spinal cord of the DM-affected dog by immunohistochemical analysis. Furthermore, a molecular epidemiological survey revealed a high carrier rate (27.6%) and mutant allele frequency (0.138) of c.118G>A in a population of Collies in Japan, suggesting that the Collie breed may be predisposed to DM associated with c.118G>A, and the prevention of DM in Collies in Japan should be addressed through epidemiological and genetic testing strategies.
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http://dx.doi.org/10.1292/jvms.16-0391DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5326944PMC
February 2017

Low expression of cyclooxygenase-2 in chronic kidney disease in young dogs.

Res Vet Sci 2016 Dec 13;109:71-73. Epub 2016 Sep 13.

Laboratory of Veterinary Clinical Pathology, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan.

Chronic kidney disease (CKD) often results in end-stage renal failure in young dogs; however, the pathogenesis of this disease is not established. This study investigated renal expression of cyclooxygenase (COX)-1 and COX-2 proteins in three dogs with chronic kidney disease by immunohistochemistry. Histopathology showed asynchronous differentiation of renal tissues, including immature glomeruli. COX-1 signals were not detected in diseased or normal kidneys. COX-2 signals were low or undetectable in diseased kidneys, while normal kidneys showed clear positive signals in the macula densa (MD). Quantitative scores of COX-2 in diseased kidneys were significantly lower than those in normal kidneys. These findings demonstrate low renal COX-2 expression in CKD in young dogs, but whether this is correlated with disease pathogenesis remains unclear.
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http://dx.doi.org/10.1016/j.rvsc.2016.09.006DOI Listing
December 2016

Amyloid precursor protein-mediated endocytic pathway disruption induces axonal dysfunction and neurodegeneration.

J Clin Invest 2016 05 11;126(5):1815-33. Epub 2016 Apr 11.

The endosome/lysosome pathway is disrupted early in the course of both Alzheimer's disease (AD) and Down syndrome (DS); however, it is not clear how dysfunction in this pathway influences the development of these diseases. Herein, we explored the cellular and molecular mechanisms by which endosomal dysfunction contributes to the pathogenesis of AD and DS. We determined that full-length amyloid precursor protein (APP) and its β-C-terminal fragment (β-CTF) act though increased activation of Rab5 to cause enlargement of early endosomes and to disrupt retrograde axonal trafficking of nerve growth factor (NGF) signals. The functional impacts of APP and its various products were investigated in PC12 cells, cultured rat basal forebrain cholinergic neurons (BFCNs), and BFCNs from a mouse model of DS. We found that the full-length wild-type APP (APPWT) and β-CTF both induced endosomal enlargement and disrupted NGF signaling and axonal trafficking. β-CTF alone induced atrophy of BFCNs that was rescued by the dominant-negative Rab5 mutant, Rab5S34N. Moreover, expression of a dominant-negative Rab5 construct markedly reduced APP-induced axonal blockage in Drosophila. Therefore, increased APP and/or β-CTF impact the endocytic pathway to disrupt NGF trafficking and signaling, resulting in trophic deficits in BFCNs. Our data strongly support the emerging concept that dysregulation of Rab5 activity contributes importantly to early pathogenesis of AD and DS.
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http://dx.doi.org/10.1172/JCI82409DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4855914PMC
May 2016

Development and application of multiple immunofluorescence staining for diagnostic cytology of canine and feline lymphoma.

Vet Clin Pathol 2015 Dec 7;44(4):580-5. Epub 2015 Dec 7.

Laboratory of Veterinary Clinical Pathology, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan.

Background: Immunophenotyping of canine and feline lymphoma to determine B-cell or T-cell origin is important for predicting prognosis and for development of treatment protocols. For advanced diagnostic cytology tests that can be performed on smears are required to predict the immunophenotype of lymphomas.

Objectives: The aim of this study was to develop a multiple immunofluorescence (MIF) staining method for the determination of lymphocyte immunophenotype in cytologic specimens, and to evaluate its clinical utility.

Methods: B cells and T cells were detected using anti-CD79α and anti-CD3 antibodies, respectively, followed by specific fluorescence-labeled secondary antibodies. The MIF staining method was first developed using fresh-frozen sections of normal canine lymph nodes. The optimal fixative, the necessity of antigen retrieval (AR), and the optimal concentration of the antibodies were determined. The MIF method was then applied to smears of normal lymph nodes, and to clinical samples from dogs and cats with lymphoma. The MIF results were compared to genetic clonality results.

Results: B and T cells were detected based on specific fluorescence in frozen sections, using formalin fixation without AR. Specific fluorescence was also detected in smears from normal lymph nodes and lymphomas, and the immunophenotypes predicted from this MIF staining method completely corresponded to those from genetic clonality analysis.

Conclusions: The MIF staining method that we developed in this study effectively distinguished lymphocyte immunophenotypes with high specificity and sensitivity using a single smear sample, and was useful as a diagnostic tool for canine and feline lymphoma.
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http://dx.doi.org/10.1111/vcp.12300DOI Listing
December 2015

Intrarenal distributions and changes of Angiotensin-converting enzyme and Angiotensin-converting enzyme 2 in feline and canine chronic kidney disease.

J Vet Med Sci 2014 Jan 5;76(1):45-50. Epub 2013 Sep 5.

Laboratory of Veterinary Clinical Pathology, Joint Faculty of Veterinary Medicine, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan.

Angiotensin-converting enzyme (ACE) is a key enzyme in the renin-angiotensin system (RAS). ACE2 is a newly identified member of the RAS. The present immunohistochemical study focused on changes in intrarenal ACE and ACE2 immunoreactivity in feline and canine chronic kidney disease (CKD). ACE immunoreactivity was predominantly observed in the brush border of the proximal tubules in dogs and cats. ACE immunoreactivity was lower in CKD kidneys than in normal kidneys, and quantitative analysis demonstrated negative correlations between ACE and renal tissue damage in dogs. ACE2 immunoreactivity was also detected in the proximal tubules; it increased or decreased with CKD in dogs, depending on the renal region assessed. The changes in ACE and ACE2 in CKD were associated with the plasma creatinine concentration in dogs. Findings from dogs with glomerulonephritis were similar to those from dogs with non-glomerulonephritis. The present study suggests that changes in the intrarenal expression of ACE and ACE2 contribute to the pathological mechanisms of canine CKD, but not to the mechanisms of feline CKD.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3979943PMC
http://dx.doi.org/10.1292/jvms.13-0314DOI Listing
January 2014

Identification of small molecule activators of cryptochrome.

Science 2012 Aug 12;337(6098):1094-7. Epub 2012 Jul 12.

Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA.

Impairment of the circadian clock has been associated with numerous disorders, including metabolic disease. Although small molecules that modulate clock function might offer therapeutic approaches to such diseases, only a few compounds have been identified that selectively target core clock proteins. From an unbiased cell-based circadian phenotypic screen, we identified KL001, a small molecule that specifically interacts with cryptochrome (CRY). KL001 prevented ubiquitin-dependent degradation of CRY, resulting in lengthening of the circadian period. In combination with mathematical modeling, our studies using KL001 revealed that CRY1 and CRY2 share a similar functional role in the period regulation. Furthermore, KL001-mediated CRY stabilization inhibited glucagon-induced gluconeogenesis in primary hepatocytes. KL001 thus provides a tool to study the regulation of CRY-dependent physiology and aid development of clock-based therapeutics of diabetes.
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http://dx.doi.org/10.1126/science.1223710DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3589997PMC
August 2012

Rapid-air-dry papanicolaou stain in canine and feline tumor cytology: a quantitative comparison with the Giemsa stain.

J Vet Med Sci 2012 Sep 18;74(9):1133-8. Epub 2012 May 18.

Laboratory of Veterinary Clinical Pathology, Department of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan.

The Papanicolaou stain is a gold-standard staining method for tumor diagnosis in human cytology. However, it has not been used routinely in veterinary cytology, because of its complicated multistep procedure and requirement for wet fixation. Currently, a rapid Papanicolaou stain using air-dried smears is utilized in human cytology, but usefulness of this rapid-air-dry Papanicolaou (RAD-Pap) stain in the veterinary field has not been fully evaluated. The purpose of this study was to evaluate the usefulness of the RAD-Pap stain by using quantitative analysis. Air-dried impression smears were collected from tumor specimens and stained with RAD-Pap and Giemsa. Twelve parameters representing the criteria of malignancy were quantitated, and characteristics of the RAD-Pap were evaluated statistically. The RAD-Pap stain could be applied to all the smears, and images of nucleoli and chromatin patterns were clear and detailed. In quantitative analysis with the RAD-Pap stain, but not with the Giemsa stain, dispersion of nucleolus size and dispersion of nucleolus/nucleus ratio in malignant tumors were significantly higher than those in benign tumors. These findings demonstrated that the RAD-Pap stain was useful for obtaining detailed nuclear information, and the ability to differentiate benignity and malignancy by nucleolus findings was a principal advantage of this stain. This RAD-Pap stain could be routinely used as a supportive staining method in veterinary diagnostic cytology.
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http://dx.doi.org/10.1292/jvms.12-0046DOI Listing
September 2012

[Circadian clocks and photoperiodism].

Fukuoka Igaku Zasshi 2012 Feb;103(2):29-34

Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University.

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February 2012

A simple and rapid immunocytochemical technique for detection of cytokeratin, vimentin, and S-100 protein in veterinary diagnostic cytology.

Res Vet Sci 2012 Dec 24;93(3):1341-5. Epub 2012 Apr 24.

Laboratory of Clinical Pathology, Department of Veterinary Medicine, Kagoshima University, and Kagoshima University Teaching Hospital, Kagoshima, Japan.

The objective of this study was to establish a simple and rapid immunocytochemical technique that can be used in veterinary diagnostic cytology. Air-dried impression smears were collected from canine tumors. Samples of epithelial tumors, mesenchymal tumors, and malignant peripheral nerve sheath tumors and melanomas were used for detection of cytokeratin, vimentin, and S-100 protein, respectively. The labeled streptavidin-biotin system was used in the present study. Optimal fixation was determined using standard immunocytochemical procedures, and acetone fixation was found to be the most effective. Optimal concentrations of primary and secondary antibodies were determined at a preset 5-min incubation. Omission of H2O2 treatment, shortening the time for blocking and labeled-streptavidin incubation, and simplifying washing did not decrease immunopositive intensities or enhance false-positive reactions. The described rapid protocol requires approximately 45 min without the use of any special equipment.
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http://dx.doi.org/10.1016/j.rvsc.2012.03.013DOI Listing
December 2012

A comparative study of chronic kidney disease in dogs and cats: induction of cyclooxygenases.

Res Vet Sci 2012 Oct 13;93(2):892-7. Epub 2012 Jan 13.

Laboratory of Veterinary Clinical Pathology, Department of Veterinary Medicine, Kagoshima University, Korimoto 1-21-24, Kagoshima 890-0065, Japan.

The present study investigated whether renal cyclooxygenase (COX) induction is associated with the severity of chronic kidney disease (CKD) in dogs and cats. The collected kidneys were examined histopathologically and immunohistochemically. The immunoreactivities of COX-1 and COX-2 were evaluated quantitatively, and the correlations to the plasma creatinine concentrations, glomerular size, glomerulosclerosis, interstitial fibrosis, and interstitial cell infiltration were evaluated statistically. Immunoreactivities for COX-1 were heterogeneously observed in the medullary distal tubules and collecting ducts; no correlations with the severity of renal damage were detected. Immunoreactivities for COX-2 were heterogeneously observed in the macula densa (MD) regions. In dogs, the percentage of COX-2-positive MD was significantly correlated with the glomerular size. In cats, glomeruli with COX-2-positive MD had significantly higher sclerosis scores than those with COX-2-negative MD. In conclusion, renal COX-2 is induced in canine and feline CKD, especially in relation to the glomerular changes.
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http://dx.doi.org/10.1016/j.rvsc.2011.12.017DOI Listing
October 2012

GIGANTEA directly activates Flowering Locus T in Arabidopsis thaliana.

Proc Natl Acad Sci U S A 2011 Jul 27;108(28):11698-703. Epub 2011 Jun 27.

Section of Cell and Developmental Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0130, USA.

Plants perceive environmental signals such as day length and temperature to determine optimal timing for the transition from vegetative to floral stages. Arabidopsis flowers under long-day conditions through the CONSTANS (CO)-FLOWERING LOCUS T (FT) regulatory module. It is thought that the environmental cues for photoperiodic control of flowering are initially perceived in the leaves. We have previously shown that GIGANTEA (GI) regulates the timing of CO expression, together with FLAVIN-BINDING, KELCH REPEAT, F BOX protein 1. Normally, CO and FT are expressed exclusively in vascular bundles, whereas GI is expressed in various tissues. To better elucidate the role of tissue-specific expression of GI in the flowering pathway, we established transgenic lines in which GI is expressed exclusively in mesophyll, vascular bundles, epidermis, shoot apical meristem, or root. We found that GI expressed in either mesophyll or vascular bundles rescues the late-flowering phenotype of the gi-2 loss-of-function mutant under both short-day and long-day conditions. Interestingly, GI expressed in mesophyll or vascular tissues increases FT expression without up-regulating CO expression under short-day conditions. Furthermore, we examined the interaction between GI and FT repressors in mesophyll. We found that GI can bind to three FT repressors: SHORT VEGETATIVE PHASE (SVP), TEMPRANILLO (TEM)1, and TEM2. Finally, our chromatin immunoprecipitation experiments showed that GI binds to FT promoter regions that are near the SVP binding sites. Taken together, our data further elucidate the multiple roles of GI in the regulation of flowering time.
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http://dx.doi.org/10.1073/pnas.1106771108DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3136272PMC
July 2011

[Molecular mechanism by which plant determines flowering timing with circadian clock].

Tanpakushitsu Kakusan Koso 2008 May;53(6):739-46

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May 2008

Photoperiodic flowering occurs under internal and external coincidence.

Plant Signal Behav 2008 Apr;3(4):269-71

Division of Biological Sciences; University of California, San Diego; La Jolla; California USA.

Determining the proper time to flower is important to ensure the reproductive success of plants. The model plant Arabidopsis is able to measure day-length and promotes flowering in long day (LD) conditions. One of the most prominent mechanisms in photoperiodic flowering is the clock-regulated gene expression of CONSTANS (CO) and the stabilization and activation of CO protein by light (regarded as external coincidence). We recently demonstrated that timing of the blue-light dependent formation of FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 (FKF1) and GIGANTEA (GI) protein complex is crucial for regulating the timing of CO gene expression. The expression of FKF1 and GI is clock regulated, and their expression patterns have the same phase in LD (regarded as internal coincidence) but not in short day (SD) conditions, where floral induction is greatly delayed. Hence, timing of the FKF1-GI complex formation is regulated by the coincidence of both external and internal cues. Here, we propose a molecular mechanism for CO regulation by FKF1-GI complex formation.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2634199PMC
http://dx.doi.org/10.4161/psb.3.4.5219DOI Listing
April 2008

FKF1 and GIGANTEA complex formation is required for day-length measurement in Arabidopsis.

Science 2007 Oct 13;318(5848):261-5. Epub 2007 Sep 13.

Department of Biochemistry, Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.

Precise timing of CONSTANS (CO) gene expression is necessary for day-length discrimination for photoperiodic flowering. The FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 (FKF1), and GIGANTEA (GI) proteins regulate CO transcription in Arabidopsis. We demonstrate that FKF1 and GI proteins form a complex in a blue-light-dependent manner. The timing of this interaction regulates the timing of daytime CO expression. FKF1 function is dependent on GI, which interacts with a CO repressor, CYCLING DOF FACTOR 1 (CDF1), and controls CDF1 stability. GI, FKF1, and CDF1 proteins associate with CO chromatin. Thus, the FKF1-GI complex forms on the CO promoter in late afternoon to regulate CO expression, providing a mechanistic view of how the coincidence of light with circadian timing regulates photoperiodic flowering.
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http://dx.doi.org/10.1126/science.1146994DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3709017PMC
October 2007

Molecular characterization of a novel RhoGAP, RRC-1 of the nematode Caenorhabditis elegans.

Biochem Biophys Res Commun 2007 Jun 9;357(2):377-82. Epub 2007 Apr 9.

Division of Oncology, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.

The GTPase-activating proteins for Rho family GTPases (RhoGAP) transduce diverse intracellular signals by negatively regulating Rho family GTPase-mediated pathways. In this study, we have cloned and characterized a novel RhoGAP for Rac1 and Cdc42, termed RRC-1, from Caenorhabditis elegans. RRC-1 was highly homologous to mammalian p250GAP and promoted GTP hydrolysis of Rac1 and Cdc42 in cells. The rrc-1 mRNA was expressed in all life stages. Using an RRC-1::GFP fusion protein, we found that RRC-1 was localized to the coelomocytes, excretory cell, GLR cells, and uterine-seam cell in adult worms. These data contribute toward understanding the roles of Rho family GTPases in C. elegans.
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http://dx.doi.org/10.1016/j.bbrc.2007.03.192DOI Listing
June 2007

Caenorhabditis elegans WASP-interacting protein homologue WIP-1 is involved in morphogenesis through maintenance of WSP-1 protein levels.

Biochem Biophys Res Commun 2006 Feb 20;340(2):709-17. Epub 2005 Dec 20.

Department of Biochemistry, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.

Mammalian WASP and N-WASP are involved in reorganization of the actin cytoskeleton through activation of the Arp2/3 complex and in regulation of cell motility or cell shape changes. In the present study, we identified WASP-interacting protein homologue (WIP)-1 in Caenorhabditis elegans. WIP-1 contains the domains and sequences conserved among mammalian WIP family proteins. Yeast two-hybrid analysis detected a physical interaction between WIP-1 and WSP-1, the sole homologue of WASP/N-WASP in C. elegans. Western analysis of embryo lysates showed that RNA interference (RNAi) treatment for wip-1 decreased levels of WSP-1 protein, and wsp-1(RNAi) treatment decreased levels of WIP-1 protein. However, wsp-1 mRNA levels were not decreased in wip-1(RNAi)-treated embryos, and wip-1 mRNA levels were not decreased in wsp-1(RNAi)-treated embryos. Furthermore, disruption of WIP-1 by RNAi resulted in embryonic lethality with morphologic defects in hypodermal cell migration, a process known as ventral enclosure. This phenotype was similar to that observed in RNAi experiments for wsp-1. Immunostaining showed that WIP-1 was expressed by migrating hypodermal cells, as was WSP-1. This expression during ventral enclosure was reduced in wip-1(RNAi)-treated embryos and wsp-1(RNAi)-treated embryos. Our results suggest that C. elegans WIP-1 may function in hypodermal cell migration during ventral enclosure by maintaining levels of WSP-1.
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http://dx.doi.org/10.1016/j.bbrc.2005.12.056DOI Listing
February 2006

Essential role of the C. elegans Arp2/3 complex in cell migration during ventral enclosure.

J Cell Sci 2003 Apr;116(Pt 8):1505-18

Department of Biochemistry, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.

Migration of cells through the reorganization of the actin cytoskeleton is essential for morphogenesis of multicellular animals. In a cell culture system, the actin-related protein (Arp) 2/3 complex functions as a nucleation core for actin polymerization when activated by the members of the WASP (Wiskott-Aldrich syndrome protein) family. However, the regulation of cell motility in vivo remains poorly understood. Here we report that homologues of the mammalian Arp2/3 complex and N-WASP in Caenorhabditis elegans play an important role in hypodermal cell migration during morphogenesis, a process known as ventral enclosure. In the absence of one of any of the C. elegans Arp2/3 complex subunits (ARX-1, ARX-2, ARX-4, ARX-5, ARX-6 or ARX-7) or of N-WASP (WSP-1), hypodermal cell migration led by actin-rich filopodia formation is inhibited during ventral enclosure owing to the reduction of filamentous actin formation. However, there is no effect on differentiation of hypodermal cells and dorsal intercalation. Disruption of the function of ARX-1 and WSP-1 in hypodermal cells also resulted in hypodermal cell arrest during ventral enclosure, suggesting that their function is cell autonomous. WSP-1 protein activated Arp2/3-mediated actin polymerization in vitro. Consistent with these results, the Arp2/3 complex and WSP-1 colocalized at the leading edge of migrating hypodermal cells. The stable localization of WSP-1 was dependent on the presence of Arp2/3 complex, suggesting an interaction between the Arp2/3 complex and WSP-1 in vivo.
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http://dx.doi.org/10.1242/jcs.00362DOI Listing
April 2003
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