Search tips
Search criteria

Results 1-8 (8)

Clipboard (0)

Select a Filter Below

Year of Publication
Document Types
author:("Kubo, takeya")
1.  Generation of Functional Insulin-Producing Cells From Mouse Embryonic Stem Cells Through 804G Cell-Derived Extracellular Matrix and Protein Transduction of Transcription Factors 
This study tried to establish an effective method of generating pancreatic β cells. Transduction of three transcription factors (Pdx1, NeuroD, and MafA) important to pancreatic β-cell development induced the differentiation of mouse embryonic stem and mouse induced pluripotent stem cells into insulin-producing cells. Results suggest the direct delivery of recombinant proteins and treatment with laminin-5-rich extracellular matrix to be useful for the generation of insulin-producing cells.
Embryonic stem (ES) and induced pluripotent stem (iPS) cells have potential applications to regenerative medicine for diabetes; however, a useful and safe way to generate pancreatic β cells has not been developed. In this study, we tried to establish an effective method of differentiation through the protein transduction of three transcription factors (Pdx1, NeuroD, and MafA) important to pancreatic β cell development. The method poses no risk of unexpected genetic modifications in target cells. Transduction of the three proteins induced the differentiation of mouse ES and mouse iPS cells into insulin-producing cells. Furthermore, a laminin-5-rich extracellular matrix efficiently induced differentiation under feeder-free conditions. Cell differentiation was confirmed with the expression of the insulin 1 gene in addition to marker genes in pancreatic β cells, the differentiated cells secreted glucose-responsive C-peptide, and their transplantation restored normoglycemia in diabetic mice. Moreover, Pdx1 protein transduction had facilitative effects on differentiation into pancreatic endocrine progenitors from human iPS cells. These results suggest the direct delivery of recombinant proteins and treatment with laminin-5-rich extracellular matrix to be useful for the generation of insulin-producing cells.
PMCID: PMC3902286  PMID: 24292793
Diabetes; Embryonic stem cells; Pancreatic differentiation; Transcription factors; Induced pluripotent stem cells
2.  Liver Abscesses after Peritoneal Venous Shunt 
Case Reports in Gastroenterology  2013;7(2):245-250.
A 70-year-old man was referred to our hospital for high-grade fever with chills. He has visited our hospital for alcoholic liver cirrhosis and diabetes mellitus for over 20 years. Nine months earlier, he had received a peritoneal venous shunt (Denver shunt®) because of refractory ascites. Laboratory examinations revealed elevated C-reactive protein and liver dysfunction. Ultrasonography and abdominal enhanced computed tomography showed multiple small abscesses in the right lobe of the liver. Blood culture test did not detect the pathogenic bacteria of liver abscesses. The patient was treated with antibiotics for more than 2 months and cured from the infection, but 3 months later, he developed high-grade fever again. He had a recurrence of multiple small liver abscesses involving both lobes of the liver. He was treated with antibiotics, and the abscesses disappeared within a month. After the antibiotic treatment, he had selective intestinal decontamination with kanamycin. He has had no recurrence of liver abscess for over a year. To our knowledge, this is the first report of liver abscess in a cirrhotic patient with Denver shunt. Clinicians should bear liver abscess in mind when treating patients with high-grade fever and liver dysfunction following Denver shunt implantation.
PMCID: PMC3712811  PMID: 23874262
Peritoneal venous shunt; Denver shunt; Liver abscess; Liver cirrhosis; Selective intestinal decontamination
3.  Fabrication of Glyconanoparticle Microarrays 
Analytical Chemistry  2012;84(7):3049-3052.
We report a new type of microarray, based on glyconanoparticles (GNPs), to study glycan-lectin interactions. GNPs, synthesized by conjugating carbohydrate ligands on silica nanoparticles, were printed on a photoactive surface followed by covalent immobilization by light activation. The GNP microarrays could be probed by lectins labeled with fluorescein as well as fluorescein-doped silica nanoparticles (FSNPs). Results showed that FSNP as the label enhanced the signals for the higher affinity ligands than the lower ones.
PMCID: PMC3405919  PMID: 22385080
4.  LPIAT1 regulates arachidonic acid content in phosphatidylinositol and is required for cortical lamination in mice 
Molecular Biology of the Cell  2012;23(24):4689-4700.
Arachidonic acid (AA) is remarkably enriched in phosphatidylinositol (PI). Studies using knockout mice of lysophosphatidylinositol acyltransferase 1, which selectively incorporates AA into PI, reveal that AA-containing PI plays a crucial role in cortical lamination and neuronal migration during brain development.
Dietary arachidonic acid (AA) has roles in growth, neuronal development, and cognitive function in infants. AA is remarkably enriched in phosphatidylinositol (PI), an important constituent of biological membranes in mammals; however, the physiological significance of AA-containing PI remains unknown. In an RNA interference–based genetic screen using Caenorhabditis elegans, we recently cloned mboa-7 as an acyltransferase that selectively incorporates AA into PI. Here we show that lysophosphatidylinositol acyltransferase 1 (LPIAT1, also known as MBOAT7), the closest mammalian homologue, plays a crucial role in brain development in mice. Lpiat1−/− mice show almost no LPIAT activity with arachidonoyl-CoA as an acyl donor and show reduced AA contents in PI and PI phosphates. Lpiat1−/− mice die within a month and show atrophy of the cerebral cortex and hippocampus. Immunohistochemical analysis reveals disordered cortical lamination and delayed neuronal migration in the cortex of E18.5 Lpiat1−/− mice. LPIAT1 deficiency also causes disordered neuronal processes in the cortex and reduced neurite outgrowth in vitro. Taken together, these results demonstrate that AA-containing PI/PI phosphates play an important role in normal cortical lamination during brain development in mice.
PMCID: PMC3521678  PMID: 23097495
5.  Common allometric response of open-grown leader shoots to tree height in co-occurring deciduous broadleaved trees 
Annals of Botany  2011;108(7):1279-1286.
Background and Aims
Morphology of crown shoots changes with tree height. The height of forest trees is usually correlated with the light environment and this makes it difficult to separate the effects of tree size and of light conditions on the morphological plasticity of crown shoots. This paper addresses the tree-height dependence of shoot traits under full-light conditions where a tree crown is not shaded by other crowns.
Focus is given to relationships between tree height and top-shoot traits, which include the shoot's leaf-blades and non-leafy mass, its total leaf-blade area and the length and basal diameter of the shoot's stem. We examine the allometric characteristics of open-grown current-year leader shoots at the tops of forest tree crowns up to 24 m high and quantify their responses to tree height in 13 co-occurring deciduous hardwood species in a cool-temperate forest in northern Japan.
Key Results
Dry mass allocated to leaf blades in a leader shoot increased with tree height in all 13 species. Specific leaf area decreased with tree height. Stem basal area was almost proportional to total leaf area in a leader shoot, where the proportionality constant did not depend on tree height, irrespective of species. Stem length for a given stem diameter decreased with tree height.
In the 13 species observed, height-dependent changes in allometry of leader shoots were convergent. This finding suggests that there is a common functional constraint in tree-height development. Under full-light conditions, leader shoots of tall trees naturally experience more severe water stress than those of short trees. We hypothesize that the height dependence of shoot allometry detected reflects an integrated response to height-associated water stress, which contributes to successful crown expansion and height gain.
PMCID: PMC3197456  PMID: 21914698
Allometry; current-year leader shoot; hierarchical Bayesian model; pipe model; tree height; water stress
6.  Polymer-Based Photocoupling Agent for the Efficient Immobilization of Nanomaterials and Small Molecules 
A highly efficient photocoupling agent, based on perfluorophenylazide (PFPA)-conjugated polyallylamine (PAAm), was developed for the efficient immobilization of polymers, nanoparticles, graphene, and small molecules. The conjugate, PAAm-PFPA, was synthesized, and the percent of the photoactive moiety, PFPA, can be controlled by the ratio of the two components in the synthesis. By treating epoxy-functionalized wafers with PAAm-PFPA, photoactive surfaces were generated. Compared with the PFPA surface, these polymer-based photocoupling matrix resulted in significantly enhanced immobilization efficiencies, especially for nanomaterials and small molecules. Thus polystyrene nanoparticles (PS NPs) and alkyl-functionalized silica nanoparticles (SNPs) were successfully immobilized on the PAAm-PFPA surface, resulting in high material density. Graphene flakes patterned on the PAAm-PFPA surface showed improved feature resolution in addition to a higher material density compared to those immobilized on the PFPA surface. Furthermore, 2-O-α-D-mannopyranosyl-D-mannopyranose (Man2) immobilized on the PAAm-PFPA surface exhibited significantly enhanced signals when treated with the lectin Concanavalin A (Con A).
PMCID: PMC3148948  PMID: 21699222
7.  Loss of Activating EGFR Mutant Gene Contributes to Acquired Resistance to EGFR Tyrosine Kinase Inhibitors in Lung Cancer Cells 
PLoS ONE  2012;7(7):e41017.
Non-small-cell lung cancer harboring epidermal growth factor receptor (EGFR) mutations attains a meaningful response to EGFR-tyrosine kinase inhibitors (TKIs). However, acquired resistance to EGFR-TKIs could affect long-term outcome in almost all patients. To identify the potential mechanisms of resistance, we established cell lines resistant to EGFR-TKIs from the human lung cancer cell lines PC9 and11–18, which harbored activating EGFR mutations. One erlotinib-resistant cell line from PC9 and two erlotinib-resistant cell lines and two gefitinib-resistant cell lines from 11–18 were independently established. Almost complete loss of mutant delE746-A750 EGFR gene was observed in the erlotinib-resistant cells isolated from PC9, and partial loss of the mutant L858R EGFR gene copy was specifically observed in the erlotinib- and gefitinib-resistant cells from 11–18. However, constitutive activation of EGFR downstream signaling, PI3K/Akt, was observed even after loss of the mutated EGFR gene in all resistant cell lines even in the presence of the drug. In the erlotinib-resistant cells from PC9, constitutive PI3K/Akt activation was effectively inhibited by lapatinib (a dual TKI of EGFR and HER2) or BIBW2992 (pan-TKI of EGFR family proteins). Furthermore, erlotinib with either HER2 or HER3 knockdown by their cognate siRNAs also inhibited PI3K/Akt activation. Transfection of activating mutant EGFR complementary DNA restored drug sensitivity in the erlotinib-resistant cell line. Our study indicates that loss of addiction to mutant EGFR resulted in gain of addiction to both HER2/HER3 and PI3K/Akt signaling to acquire EGFR-TKI resistance.
PMCID: PMC3398867  PMID: 22815900
8.  Ergatoid queen development in the ant Myrmecina nipponica: modular and heterochronic regulation of caste differentiation 
Caste polyphenism in social insects provides us with excellent opportunities to examine the plasticity and robustness underlying developmental pathways. Several ant species have evolved unusual castes showing intermediate morphologies between alate queens and wingless workers. In some low-temperature habitats, the ant Myrmecina nipponica produces such intermediate reproductives (i.e. ergatoids), which can mate and store sperm but cannot fly. To gain insight into the developmental and evolutionary aspects associated with ergatoid production, we conducted morphological and histological examinations of the post-embryonic development of compound eyes, gonads and wings during the process of caste differentiation. In compound eyes, both the queen-worker and ergatoid-worker differences were already recognized at the third larval instar. In gonads, queen-worker differentiation began at the larval stage, and ergatoid-worker differentiation began between the prepupal and pupal stages. Wing development in ergatoids was generally similar to that in workers throughout post-embryonic development. Our results showed that the developmental rate and timing of differentiation in body parts differed among castes and among body parts. These differences suggest that the rearrangement of modular body parts by heterochronic developmental regulation is responsible for the origination of novel castes, which are considered to be adaptations to specific ecological niches.
PMCID: PMC2880103  PMID: 20200029
caste development; heterochrony; imaginal primordia; modularity; social insect

Results 1-8 (8)