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Search Results: 1 - 10 of 848 matches for " Kazushiro Fujiwara "
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Antagonistic Interplay between Necdin and Bmi1 Controls Proliferation of Neural Precursor Cells in the Embryonic Mouse Neocortex
Ryohei Minamide, Kazushiro Fujiwara, Koichi Hasegawa, Kazuaki Yoshikawa
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0084460
Abstract: Neural precursor cells (NPCs) in the neocortex exhibit a high proliferation capacity during early embryonic development and give rise to cortical projection neurons after maturation. Necdin, a mammal-specific MAGE (melanoma antigen) family protein that possesses anti-mitotic and pro-survival activities, is expressed abundantly in postmitotic neurons and moderately in tissue-specific stem cells or progenitors. Necdin interacts with E2F transcription factors and suppresses E2F1-dependent transcriptional activation of the cyclin-dependent kinase Cdk1 gene. Here we show that necdin serves as a suppressor of NPC proliferation in the embryonic neocortex. Necdin is moderately expressed in the ventricular zone of mouse embryonic neocortex, in which proliferative cell populations are significantly increased in necdin-null mice. In the neocortex of necdin-null embryos, expression of Cdk1 and Sox2, a stem cell marker, is significantly increased, whereas expression of p16, a cyclin-dependent kinase inhibitor, is markedly diminished. Cdk1 and p16 expression levels are also significantly increased and decreased, respectively, in primary NPCs prepared from necdin-null embryos. Intriguingly, necdin interacts directly with Bmi1, a Polycomb group protein that suppresses p16 expression and promotes NPC proliferation. In HEK293A cells transfected with luciferase reporter constructs, necdin relieves Bmi1-dependent repression of p16 promoter activity, whereas Bmi1 counteracts necdin-mediated repression of E2F1-dependent Cdk1 promoter activity. In lentivirus-infected primary NPCs, necdin overexpression increases p16 expression, suppresses Cdk1 expression, and inhibits NPC proliferation, whereas Bmi1 overexpression suppresses p16 expression, increases Cdk1 expression, and promotes NPC proliferation. Our data suggest that embryonic NPC proliferation in the neocortex is regulated by the antagonistic interplay between necdin and Bmi1.
Necdin Promotes Ubiquitin-Dependent Degradation of PIAS1 SUMO E3 Ligase
Ibrahim Gur, Kazushiro Fujiwara, Koichi Hasegawa, Kazuaki Yoshikawa
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0099503
Abstract: Necdin, a pleiotropic protein that promotes differentiation and survival of mammalian neurons, is a member of MAGE (melanoma antigen) family proteins that share a highly conserved MAGE homology domain. Several MAGE proteins interact with ubiquitin E3 ligases and modulate their activities. However, it remains unknown whether MAGE family proteins interact with SUMO (small ubiquitin-like modifier) E3 ligases such as PIAS (protein inhibitor of activated STAT) family, Nsmce2/Mms21 and Cbx4/Pc2. In the present study, we examined whether necdin interacts with these SUMO E3 ligases. Co-immunoprecipitation analysis revealed that necdin, MAGED1, MAGEF1 and MAGEL2 bound to PIAS1 but not to Nsmce2 or Cbx4. These SUMO E3 ligases bound to MAGEA1 but failed to interact with necdin-like 2/MAGEG1. Necdin bound to PIAS1 central domains that are highly conserved among PIAS family proteins and suppressed PIAS1-dependent sumoylation of the substrates STAT1 and PML (promyelocytic leukemia protein). Remarkably, necdin promoted degradation of PIAS1 via the ubiquitin-proteasome pathway. In transfected HEK293A cells, amino- and carboxyl-terminally truncated mutants of PIAS1 bound to necdin but failed to undergo necdin-dependent ubiquitination. Both PIAS1 and necdin were associated with the nuclear matrix, where the PIAS1 terminal deletion mutants failed to localize, implying that the nuclear matrix is indispensable for necdin-dependent ubiquitination of PIAS1. Our data suggest that necdin suppresses PIAS1 both by inhibiting SUMO E3 ligase activity and by promoting ubiquitin-dependent degradation.
Necdin Controls Proliferation of White Adipocyte Progenitor Cells
Kazushiro Fujiwara, Koichi Hasegawa, Tsuyoshi Ohkumo, Hiroyuki Miyoshi, Yu-Hua Tseng, Kazuaki Yoshikawa
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0030948
Abstract: White adipose tissues are composed mainly of white fat cells (adipocytes), which play a key role in energy storage and metabolism. White adipocytes are terminally differentiated postmitotic cells and arise from their progenitor cells (preadipocytes) or mesenchymal stem cells residing in white adipose tissues. Thus, white adipocyte number is most likely controlled by the rate of preadipocyte proliferation, which may contribute to the etiology of obesity. However, little is known about the molecular mechanisms that regulate preadipocyte proliferation during adipose tissue development. Necdin, which is expressed predominantly in postmitotic neurons, is a pleiotropic protein that possesses anti-mitotic and pro-survival activities. Here we show that necdin functions as an intrinsic regulator of white preadipocyte proliferation in developing adipose tissues. Necdin is expressed in early preadipocytes or mesenchymal stem cells residing in the stromal compartment of white adipose tissues in juvenile mice. Lentivirus-mediated knockdown of endogenous necdin expression in vivo in adipose tissues markedly increases fat mass in juvenile mice fed a high-fat diet until adulthood. Furthermore, necdin-null mutant mice exhibit a greater expansion of adipose tissues due to adipocyte hyperplasia than wild-type mice when fed the high-fat diet during the juvenile and adult periods. Adipose stromal-vascular cells prepared from necdin-null mice differentiate in vitro into a significantly larger number of adipocytes in response to adipogenic inducers than those from wild-type mice. These results suggest that necdin prevents excessive preadipocyte proliferation induced by adipogenic stimulation to control white adipocyte number during adipose tissue development.
Triadic Synchrony: Application of Multiple Wavelet Coherence to a Small Group Conversation  [PDF]
Ken Fujiwara
Applied Mathematics (AM) , 2016, DOI: 10.4236/am.2016.714126
Abstract: By applying multiple wavelet coherence (MWC) to data from human body movements in triadic interaction, this study quantified triadic synchrony, rhythmic similarity among three interactants. Thirty-nine Japanese undergraduates were randomly assigned in a triad, and engaged in a brain-storming task. Triadic synchrony was quantified by calculating MWC to the time-series movement data collected by Kinect v2 sensor. The existence of synchrony was statistically tested by using a pseudo-synchrony paradigm. Results showed that the averaged value of MWC was higher in the experimental participant trio than in those of the pseudo trio in the frequency band of 0.5 - 1 Hz. The result supports the possible utility of applying multiple wavelet coherence to evaluate triadic synchrony in a small group interaction.
Photobiont Flexibility in Paramecium bursaria: Double and Triple Photobiont Co-Habitation  [PDF]
Ryo Hoshina, Yuko Fujiwara
Advances in Microbiology (AiM) , 2012, DOI: 10.4236/aim.2012.23027
Abstract: The green ciliate, Paramecium bursaria, has evolved a mutualistic relationship with endosymbiotic green algae (photobionts). Under culture conditions, photobionts are usually unified (to be single species) within each P. bursaria strain. In most cases, the algal partners are restricted to either Chlorella variabilis or Micractinium reisseri (Chlorellaceae, Trebouxiophyceae). Both species are characterized by particular physiology and atypical group I intron insertions, although they are morphologically indistinguishable from each other or from other Chlorella-related species. Both algae are exclusive species that are viable only within P. bursaria cells, and therefore their symbiotic relationship can be considered persistent. In a few cases, the other algal species have been reported as P. bursaria photobionts. Namely, P. bursaria have occasionally replaced their photobiont partner. This paper introduces some P. bursaria strains that maintain more than one species of algae for a long period. This situation prompts speculations about flexibility of host-photo-biont relationships, how P. bursaria replaced these photobionts, and the infection theory of the group I introns.
Roles of Sex Steroids in the Crowings with Sexual and Non-Sexual Motivations in Female Japanese Quail, Coturnix Japonica  [PDF]
Atsuhiko Chiba, Masaya Fujiwara
Journal of Behavioral and Brain Science (JBBS) , 2013, DOI: 10.4236/jbbs.2013.33028
Abstract: To examine the sex differences in the crowing behavior of the Japanese quail, we investigated the effects of sex steroids on calling behaviors using female birds, and the data were compared with those obtained in our previous study in male birds which was performed using the same experimental procedures as those in the present study. We injected the female quails daily from 11 to 41 days after hatching with testosterone propionate (TP), 5α-dihydrotestosterone (DHT; a non-aromatizable androgen), estradiol benzoate (EB) or vehicle, and examined their calling behaviors in both sexual and non-sexual contexts. In a non-sexual context of the birds being isolated in a recording chamber, androgens, either TP or DHT, induced crowing in place of distress calling while EB simply inhibited distress calling. These effects of sex steroids on the calling behaviors were almost identical to those in the male quails. In a sexual context of the birds being left undisturbed in their home cages, crowing was induced by chronic treatment with TP, but not either DHT or EB, suggesting that both estrogenic and androgenic actions are required to induce the sexually motivated crowing. Although these results were basically the same as those in the male quails, the crowing in the female quails occurred much less frequently compared to that of the male quails. These data suggest that in the Japanese quail, crowing behavior, when it is restricted to sexually motivated one, is quantitatively different between male and female in the responsiveness to sex steroids.

A New Analysis Concept in Applying Software Reliability Growth Models and Tool Implementation: The SafeMan  [PDF]
Takaji Fujiwara, Mitsuhiro Kimura
Journal of Software Engineering and Applications (JSEA) , 2014, DOI: 10.4236/jsea.2014.75036
Abstract:

In recent years, many software development organizations have been assessing and analyzing their software product’s reliability/quality and judging whether the software product is releasable by using Software Reliability Growth Models (SRGMs) at the final stage of software development. The usage of SRGMs originates in the advantage that various reliability analysis results based on the SRGMs can be acquired easily. However, it is very difficult for general software project managers to grasp the achievement level of reliability/quality based on its analysis results because some sort of professional knowledge is required in order to understand the information on the attainment progress of software product’s reliability/quality. Moreover, it is also difficult for software project managers and inspectors who do not deeply comprehend the details of their project to evaluate the degree of software reliability and quality, if they assess it without grasping the live development situation and only see the documents submitted from their staff. In this paper, we propose a new analysis concept for assessing the software product’s reliability/quality, and illustrate the output results obtained by a tool, the SafeMan.

Analysis of Psychological Factors That Influence Preference for Luxury Food and Car Brands Targeting Japanese People  [PDF]
Kazutoshi Fujiwara, Shin’ya Nagasawa
American Journal of Industrial and Business Management (AJIBM) , 2015, DOI: 10.4236/ajibm.2015.59059
Abstract: This study examines the strong preference among Japanese people for luxury brands and makes a comparative analysis of the psychological factors that influence the development of purchase intentions and how they differ between the food and car luxury brands. An empirical analysis was performed by using psychological factors that influence the preference for luxury brands, which Sugimoto [1] demonstrated in a study on Japanese people. The results suggested the following: 1) Differentiation from Others is an important factor in developing purchase intentions for both food and car luxury brands and is a particularly important factor for cars; 2) Conformity to Group Norms is not an important factor in developing purchase intentions for both food and car luxury brands in which consumers continue to feel a sense of rarity; 3) Avoiding Cognitive Dissonance is an important factor in developing purchase intentions for both food and car luxury brands; 4) Quality Evaluation is an important factor in developing purchase intentions for food luxury brands only.
Relationships among Purchase Intentions for Luxury Brands and Personality Traits Based on the Big Five  [PDF]
Kazutoshi Fujiwara, Shin’ya Nagasawa
American Journal of Industrial and Business Management (AJIBM) , 2015, DOI: 10.4236/ajibm.2015.511063
Abstract: Fujiwara and Nagasawa [1] verified differences in the degree of effect of the four psychological factors1 that constituted Japanese people’s preference for luxury brands on the development of purchase intentions for luxury food and car brands. This study is related to the study mentioned above and verifies the effects of consumers’ personality traits on purchase intentions for these luxury brands. It uses a personality trait classification method called the “Big Five personality traits” to perform an empirical analysis of the way that the five dimensions of personality traits4 influence purchase intentions for each brand. As a result, it suggests 1) that the purchase intentions of emotionally unstable consumers with a high dimension of Neuroticism for FERRARI and PORSCHE are significantly lower than those with a low dimension of Neuroticism and 2) that the purchase intentions of consumers who are highly devoted to art and have a high dimension of Openness to Experience for DOM PERIGNON, FERRARI, ROLLS-ROYCE and PORSCHE are significantly higher than those with a low dimension of Openness to Experience.
Psychological Factors That Influence Preference for Luxury Brands: Effect of “Openness to Experience1” on Psychological Factors for the Development of Purchase Intentions  [PDF]
Kazutoshi Fujiwara, Shin’ya Nagasawa
American Journal of Industrial and Business Management (AJIBM) , 2015, DOI: 10.4236/ajibm.2015.512077
Abstract: Fujiwara & Nagasawa [1] performed an empirical analysis on the relationship between personality traits and purchase intentions for food and car luxurybrands2 by using the Big Five personality traits. The results revealed that consumers with high levels of Openness to Experience showed high purchase intentions for those brands. The objective of this study was to refine those results and to reveal the characteristics of psychological factors regarding the development of purchase intentions for consumers with high levels of Openness to Experience. As a result of empirical analysis using multiple regression analysis, this study demonstrated that satisfying the need for Differentiation from Others was particularly important in developing purchase intentions for those consumers with high levels of Openness to Experience for both food and car luxury brands.
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