Biomedical subjects

Kenji Fukasawa

Publications and source records attributed to Kenji Fukasawa.

At least 19 recordsLinked to original sources

PubMed2006

Interaction between ROCK II and nucleophosmin/B23 in the regulation of centrosome duplication.

Nucleophosmin (NPM)/B23 has been implicated in the regulation of centrosome duplication. NPM/B23 localizes between two centrioles in the unduplicated centrosome. Upon phosphorylation on Thr(199) by cyclin-dependent kinase 2 (CDK2)/cyclin E, the majority of centrosomal NPM/B23 dissociates from centrosomes, but some NPM/B23 phosphorylated on Thr(199) remains at centrosomes. It has been shown that Thr(199) phosphorylation of NPM/B23 is critical for the physical separation of the paired centrioles, an initial event of the centrosome duplication process. Here, we identified ROCK II kinase, an effector of Rho small GTPase, as a protein that localizes to centrosomes and physically interacts with NPM/B23. Expression of the constitutively active form of ROCK II promotes centrosome duplication, while down-regulation of ROCK II expression results in the suppression of centrosome duplication, especially delaying the initiation of centrosome duplication during the cell cycle. Moreover, ROCK II regulates centrosome duplication in its kinase and centrosome localization activity-dependent manner. We further found that ROCK II kinase activity is significantly enhanced by binding to NPM/B23 and that NPM/B23 acquires a higher binding affinity to ROCK II upon phosphorylation on Thr(199). Moreover, physical interaction between ROCK II and NPM/B23 in vivo occurs in association with CDK2/cyclin E activation and the emergence of Thr(199)-phosphorylated NPM/B23. All these findings point to ROCK II as the effector of the CDK2/cyclin E-NPM/B23 pathway in the regulation of centrosome duplication.

Animals↗

PubMed2006

Validation of the Karolinska sleepiness scale against performance and EEG variables.

OBJECTIVE: The Karolinska sleepiness scale (KSS) is frequently used for evaluating subjective sleepiness. The main aim of the present study was to investigate the validity and reliability of the KSS with electroencephalographic, behavioral and other subjective indicators of sleepiness. METHODS: Participants were 16 healthy females aged 33-43 (38.1+/-2.68) years. The experiment involved 8 measurement sessions per day for 3 consecutive days. Each session contained the psychomotor vigilance task (PVT), the Karolinska drowsiness test (KDT-EEG alpha & theta power), the alpha attenuation test (AAT-alpha power ratio open/closed eyes) and the KSS. RESULTS: Median reaction time, number of lapses, alpha and theta power density and the alpha attenuation coefficients (AAC) showed highly significant increase with increasing KSS. The same variables were also significantly correlated with KSS, with a mean value for lapses (r=0.56). CONCLUSIONS: The KSS was closely related to EEG and behavioral variables, indicating a high validity in measuring sleepiness. SIGNIFICANCE: KSS ratings may be a useful proxy for EEG or behavioral indicators of sleepiness.

Adult↗

PubMed2006

Suppression of centrosome amplification after DNA damage depends on p27 accumulation.

The centrosome plays a fundamental role in cell division, cell polarity, and cell cycle progression. Centrosome duplication is mainly controlled by cyclin-dependent kinase 2 (CDK2)/cyclin E and cyclin A complexes, which are inhibited by the CDK inhibitors p21Cip1 and p27Kip1. It is thought that abnormal activation of CDK2 induces centrosome amplification that is frequently observed in a wide range of aggressive tumors. We previously reported that overexpression of the oncogene MYCN leads to centrosome amplification after DNA damage in neuroblastoma cells. We here show that centrosome amplification after gamma-irradiation was caused by suppression of p27 expression in MYCN-overexpressing cells. We further show that p27-/- and p27+/- mouse embryonic fibroblasts and p27-silenced human cells exhibited a significant increase in centrosome amplification after DNA damage. Moreover, abnormal mitotic cells with amplified centrosomes were frequently observed in p27-silenced cells. In response to DNA damage, the level of p27 gradually increased in normal cells independently of the ataxia telangiectasia mutated/p53 pathway, whereas Skp2, an F-box protein component of an SCF ubiquitin ligase complex that targets p27, was reduced. Additionally, p27 levels in MYCN-overexpressing cells were restored by treatment with Skp2 small interfering RNA, indicating that down-regulation of p27 by MYCN was due to high expression of Skp2. These results suggest that the accumulation of p27 after DNA damage is required for suppression of centrosome amplification, thereby preventing chromosomal instability.

Ataxia Telangiectasia Mutated Proteins↗

PubMed2006

Psychosocial work characteristics predicting daytime sleepiness in day and shift workers.

Characteristics of work organization other than working time arrangements may contribute importantly to daytime sleepiness. The present study was designed to identify the psychosocial factors at work that predict daytime sleepiness in a sample of day and shift workers. Participants working at a pulp and chemical factory completed an annual questionnaire regarding psychosocial factors at work using the U.S. National Institute for Occupational Safety and Health Generic Job Stress Questionnaire (i.e., quantitative workload, variance in workload, job control, support from supervisor, coworkers, or family/friends, job satisfaction, and depressive symptoms), as well as daytime sleepiness (through the Epworth Sleepiness Scale [ESS]) and sleep disturbances for three years starting in 2002 (response rates, 94.6-99.0%). The present analysis included 55 day workers (11 women) and 57 shift workers (all men) who participated in all three years of the study, worked under the same work schedule throughout the study period, and had no missing data on any of the daytime sleep items. A repeated-measures analysis of covariance (ANCOVA) was used to test the effects of work schedule (day vs. shift work) and psychosocial factors at work in 2002 on the ESS scores in subsequent years, with sleep duration, insomnia symptoms, chronic diseases, and sleepiness levels at baseline as covariates. Given significant and near-significant interactions of work schedules with psychosocial factor or study year, the ANCOVA, with the factors of psychosocial work characteristics and study year, was performed by type of work schedule. The results indicated a significant main effect of psychosocial work characteristics (p = 0.010, partial eng2 = 0.14) and an almost significant main effect of study year (p = 0.067, partial eng2 = 0.06) and interaction between psychosocial work characteristics and study year (p = 0.085, partial eng2 = 0.06) for variance in workload among the day work group. The day workers reporting high variance in workload in 2002 exhibited significantly higher ESS scores in 2003 and 2004 than did those reporting low variance in workload. The ANCOVA for the shift work group showed a main effect of psychosocial work characteristics for job satisfaction (p = 0.026, partial eng2 = 0.10) and depressive symptoms (p = 0.094, partial eng2 = 0.06) with the interaction between psychosocial work characteristics and study year for job satisfaction (p = 0.172, partial eng2 = 0.04) and depressive symptoms (p = 0.035, partial eng2 = 0.07). The shift workers with low job satisfaction and high symptoms of depression in 2002 showed significantly greater ESS scores in 2003 and/or 2004 than did those with opposite characteristics. These results may suggest a potential predictive value of variance in workload for day workers as well as job satisfaction and depressive symptoms for shift workers with respect to daytime sleepiness. The present findings may imply that redesigning these aspects of work environment would be of help in managing daytime sleepiness.

Adult↗

PubMed2006

Indoor exposure to natural bright light prevents afternoon sleepiness.

STUDY OBJECTIVES: The present study examined the effects of indoor exposure to natural bright light on afternoon sleepiness. DESIGN: Participants took part in 3 experimental conditions: (1) a natural bright light condition in which they carried out performance and arousal tests sitting near a window (3260.0 +/- 1812.43 lux) from 12:40 PM to 1:10 PM, (2) a nap condition in which they were provided a nap opportunity for 20 minutes from 12:45 PM, and (3) a control condition in which they performed the tests in less than 100 lux surroundings from 12:40 PM to 1:10 PM. Before and after each treatment, the same series of tests were administered. SETTING: A temperature- and light-controlled sleep laboratory. PARTICIPANTS: Sixteen healthy female paid volunteers aged 33 to 43 (38.1 +/- 2.68) years. INTERVENTIONS: Indoor natural bright light and a short nap. MEASUREMENTS AND RESULTS: Arousal levels were measured by the Psychomotor Vigilance Task, Alpha Attenuation Test, Karolinska Drowsiness Test, and Karolinska Sleepiness Scale. The tests were repeated every 30 minutes from 11:00 AM to 4:10 PM. Ambient light intensity was maintained at less than 100 lux, except during natural bright light exposure. Short-term exposure to natural bright light significantly improved afternoon arousal levels, as measured by the Karolinska Drowsiness Test and Alpha Attenuation Test, the effects of which continued for at least 60 minutes (1:10-2:10 PM). However, no significant differences were observed between conditions for Psychomotor Vigilance Test performance. CONCLUSIONS: Brief indoor exposure to natural bright light may decrease afternoon sleepiness. This technique of light could be used in work settings in which napping is not permitted.

Adult↗

PubMed2006

Perceived sleepiness of non-shift working men in two different types of work organization.

Increased sleepiness at work is increasingly being focused on as a safety and health issue. However, research on workers' sleepiness is very limited in scope and the characteristics of work organization, including the impact of job stress, have not been fully addressed. A questionnaire survey was conducted to investigate the prevalence of daytime sleepiness and its associated factors among non-shift working men at two manufacturing businesses: Company A, having a rapid rate of development and growth, with 564 workers (19-61 yr old, mean age: 32.7, response rate: 81.4%); and Company B, long established, possessing a huge production facility, with 1,654 workers (20-63 yr old, mean age: 37.1, response rate: 78.2%). The prevalence of daytime sleepiness was 11.3% in company A and 16.8% in company B. Multivariate logistic regression analysis revealed that, in company A, perceived sleepiness was associated with long sleep duration on non-working days and high cognitive demands and, in company B, with insufficient daily sleep, single, and depression. Psychosomatic exhaustion resulting from jobs requiring high adaptivity due to rapid frequency of operational change as in company A may have the potential to become an important factor in perceived sleepiness. However, in a comparatively stable work organization, as in company B, increased sleepiness may be mainly linked to factors outside work. It is suggested that not only lifestyle and sleep habits, but also the characteristics and dynamics of a work organization should be a focus of attention when planning measures to prevent sleepiness at work.

Adult↗

PubMed2005

Thr199 phosphorylation targets nucleophosmin to nuclear speckles and represses pre-mRNA processing.

Nucleophosmin (NPM) is a multifunctional phosphoprotein, being involved in ribosome assembly, pre-ribosomal RNA processing, DNA duplication, nucleocytoplasmic protein trafficking, and centrosome duplication. NPM is phosphorylated by several kinases, including nuclear kinase II, casein kinase 2, Polo-like kinase 1 and cyclin-dependent kinases (CDK1 and 2), and these phosphorylations modulate the activity and function of NPM. We have previously identified Thr(199) as the major phosphorylation site of NPM mediated by CDK2/cyclin E (and A), and this phosphorylation is involved in the regulation of centrosome duplication. In this study, we further examined the effect of CDK2-mediated phosphorylation of NPM by using the antibody that specifically recognizes NPM phosphorylated on Thr(199). We found that the phospho-Thr(199) NPM localized to dynamic sub-nuclear structures known as nuclear speckles, which are believed to be the sites of storage and/or assembly of pre-mRNA splicing factors. Phosphorylation on Thr(199) by CDK2/cyclin E (and A) targets NPM to nuclear speckles, and enhances the RNA-binding activity of NPM. Moreover, phospho-Thr(199) NPM, but not unphosphorylated NPM, effectively represses pre-mRNA splicing. These findings indicate the involvement of NPM in the regulation of pre-mRNA processing, and its activity is controlled by CDK2-mediated phosphorylation on Thr(199).

Animals↗

PubMed2005

Centrosome amplification, chromosome instability and cancer development.

During mitosis, two centrosomes form spindle poles and direct the formation of bipolar mitotic spindles, which is an essential event for accurate chromosome segregation into daughter cells. The presence of more than two centrosomes (centrosome amplification), severely disturbs mitotic process and cytokinesis via formation of more than two spindle poles, resulting in an increased frequency of chromosome segregation errors (chromosome instability). Destabilization of chromosomes by centrosome amplification aids acquisition of further malignant phenotypes, hence promoting tumor progression. Centrosome amplification occurs frequently in almost all types of cancer, and is considered as the major contributing factor for chromosome instability in cancer cells. Upon cytokinesis, each daughter cell receives one centrosome, and thus centrosome must duplicate once, and only once, before the next mitosis. If centrosomes duplicate more than once within a single cell cycle, centrosome amplification occurs, which is frequently seen in cells harboring mutations in some tumor suppressor proteins such as p53 and BRCA1. The recent studies have provided critical information for understanding how loss of these proteins allows multiple rounds of centrosome duplication. In this review, how centrosome amplification destabilizes chromosomes, how loss of certain tumor suppressor proteins leads to centrosome amplification, and the role of centrosome amplification in cancer development will be discussed.

Cell Cycle↗

PubMed2005

Oncogenic RAS induces accelerated transition through G2/M and promotes defects in the G2 DNA damage and mitotic spindle checkpoints.

Activating mutations of RAS are prevalent in thyroid follicular neoplasms, which commonly have chromosomal losses and gains. In thyroid cells, acute expression of HRAS(V12) increases the frequency of chromosomal abnormalities within one or two cell cycles, suggesting that RAS oncoproteins may interfere with cell cycle checkpoints required for maintenance of a stable genome. To explore this, PCCL3 thyroid cells with conditional expression of HRAS(V12) or HRAS(V12) effector mutants were presynchronized at the G(1)/S boundary, followed by activation of expression of RAS mutants and release from the cell cycle block. Expression of HRAS(V12) accelerated the G(2)/M phase by approximately 4 h and promoted bypass of the G(2) DNA damage and mitotic spindle checkpoints. Accelerated passage through G(2)/M and bypass of the G(2) DNA damage checkpoint, but not bypass of the mitotic spindle checkpoint, required activation of mitogen-activated protein kinase (MAPK). However, selective activation of the MAPK pathway was not sufficient to disrupt the G(2) DNA damage checkpoint, because cells arrested appropriately in G(2) despite conditional expression of HRAS(V12,S35) or BRAF(V600E). By contrast to the MAPK requirement for radiation-induced G(2) arrest, RAS-induced bypass of the mitotic spindle checkpoint was not prevented by pretreatment with MEK inhibitors. These data support a direct role for the MAPK pathway in control of G(2) progression and regulation of the G(2) DNA damage checkpoint. We propose that oncogenic RAS activation may predispose cells to genomic instability through both MAPK-dependent and independent pathways that affect critical checkpoints in G(2)/M.

Animals↗

PubMed2005

Characterization of centrosomal association of nucleophosmin/B23 linked to Crm1 activity.

Nucleophosmin (NPM)/B23 is a multifunctional protein, involving in a wide variety of basic cellular processes, including ribosome assembly, DNA duplication, nucleocytoplasmic trafficking, and centrosome duplication. It has previously been shown that NPM/B23 localizes to centrosomes, and dissociate from centrosomes upon phosphorylation by Cdk2/cyclin E. However, detail characterization of centrosomal association of NPM/B23 has been hampered by the lack of appropriate antibodies that efficiently detects centrosomally localized NPM/B23, as well as by apparent loss of natural behavior of NPM/B23 when tagged with fluorescent proteins. Here, by the use of newly generated anti-NPM/B23 antibody, we conducted a careful analysis of centrosomal localization of NPM/B23. We found that NPM/B23 localizes between the paired centrioles of unduplicated centrosomes, suggesting the role of NPM/B23 in the centriole pairing. Upon initiation of centrosome duplication, some NPM/B23 proteins remain at mother centrioles of the parental centriole pairs. We further found that inhibition of Crm1 nuclear export receptor results in both accumulation of cyclin E at centrosomes and efficient dissociation of NPM/B23 from centrosomes.

Animals↗

PubMed2005

Liver-specific pRB loss results in ectopic cell cycle entry and aberrant ploidy.

The liver exhibits an exquisitely controlled cell cycle, wherein hepatocytes are maintained in quiescence until stimulated to proliferate. The retinoblastoma tumor suppressor, pRB, plays a central role in proliferative control by inhibiting inappropriate cell cycle entry. In many cases, liver cancer arises due to aberrant cycles of proliferation, and correspondingly, pRB is functionally inactivated in the majority of hepatocellular carcinomas. Therefore, to determine how pRB loss may provide conditions permissive for deregulated hepatocyte proliferation, we investigated the consequence of somatic pRB inactivation in murine liver. We show that liver-specific pRB loss results in E2F target gene deregulation and elevated cell cycle progression during post-natal growth. However, in adult livers, E2F targets are repressed and hepatocytes become quiescent independent of pRB, suggesting that other factors may compensate for pRB loss. Therefore, to probe the consequences of acute pRB inactivation in livers of adult mice, we gave adenoviral-Cre by i.v. injection. We show that acute pRB loss is sufficient to elicit E2F target gene expression and cell cycle entry in adult liver, demonstrating a critical role for pRB in maintaining hepatocyte quiescence. Finally, we show that liver-specific pRB loss results in the development of nuclear pleomorphism associated with elevated ploidy that is evident in adult mice harboring both acute and chronic pRB loss. Together, these results show the crucial role played by pRB in maintaining hepatocyte quiescence and ploidy in adult liver in vivo and underscore the critical importance of delineating the consequences of acute pRB loss in adult animals.

Animals↗

PubMed2005

Transcriptional control of BubR1 by p53 and suppression of centrosome amplification by BubR1.

Elimination of the regulatory mechanism underlying numeral homeostasis of centrosomes, as seen in cells lacking p53, results in abnormal amplification of centrosomes, which increases the frequency of chromosome segregation errors, and thus contributes to the chromosome instability frequently observed in cancer cells. We have previously reported that p53(-/-) mouse cells in prolonged culture undergo genomic convergence similar to that observed during tumor progression; early-passage p53(-/-) cells are karyotypically heterogeneous due to extensive chromosome instability associated with centrosome amplification, while late-passage p53(-/-) cells are aneuploid yet karyotypically homogeneous and chromosomally stable. Moreover, they contain numerically normal centrosomes. Through the microarray analysis of early- and late-passage p53(-/-) cells, we identified the BubR1 spindle checkpoint protein, which plays a critical role in suppression of centrosome amplification and stabilization of chromosomes in late-passage p53(-/-) cells. Up-regulation of BubR1 augments the checkpoint function, which effectively senses the spindle/chromosome aberrations associated with centrosome amplification. We further found that BubR1 transcription is largely controlled by p53. In early-passage p53(-/-) cells, BubR1 expression is low and the checkpoint function in response to microtubule toxin is considerably compromised. In late-passage cells, however, regaining of BubR1 expression restores the checkpoint function to mitotic aberrations caused by microtubule toxin. Our studies demonstrate the molecular aspect of genomic convergence in cultured cells, providing critical information for understanding the stepwise progression of tumors.

Animals↗

PubMed2005

Association of change in the type of job with prevalence of components of the metabolic syndrome-special reference to job stress.

OBJECTIVE: It is well established that job stress is a leading cause of cardiovascular disease. The relationship with the metabolic syndrome, however, has received only limited attention. The present study was designed to investigate associations between change of the type of job and the prevalence of metabolic syndrome components from the aspect of on-the-job stress and alteration in life style. METHODS: Thirty-six male workers of the manufacturing department were transferred to the carsales department at the same automobile company in 1992 to 1993. These same workers were transferred back to the manufacturing department after two years. We compared the first health-check data before the transfer in 1992 (Term A), a second set of data two years after transfer in 1994-95 (Term B) and a third set of data two years following transfer back to the manufacturing department in 1996-1998 (Term C). The workers were requested to provide information about drinking and smoking habits, and answer Karasek's questionnaire and a simple stress questionnaire in order to clarify the possibility of job stress in occurrence of the metabolic syndrome, defined in terms of obesity, hypertension, dyslipidemia, and impaired glucose tolerance as components. RESULTS: Five workers had two or more components of the metabolic syndrome before the transfer to the car-sales department (Group I). One demonstrated improvement, three no change, and one increase in symptoms from A to B. Seven workers had more than two components after the transfer to car-sales department (Group II), and six of them exhibited decrease two years following transfer back to the manufacturing department. Five of them also showed elevated liver enzymes in serum with the appearance of the components, and three of them demonstrated recover. Three workers had two components of the metabolic syndrome only at time point C (Group III), while the remaining 21 workers had 0 to one component throughout the observation period (Group IV). Amount of drinking and smoking increased significantly when working in the sales department but these items returned to the previous values after rejoining manufacturing, though differences were not observed between workers with (Group II) and without (Group IV) components of the metabolic syndrome. Body mass index (BMI) and alanine aminotransferase (ALT) increased significantly when workers moved to the sales department and that was significant in Group II as compared to Group IV. Three components of Karasek's JCQ changed significantly during job transfer, though differences were not observed between the workers with (Group II) and without (Group IV) components of the metabolic syndrome. Logistic regression analysis with age, lifestyle, Karasek's JCQ, and ALT revealed that elevation of ALT value was associated with having two or more components of metabolic syndrome, while hours of sleep demonstrated an inverse association. CONCLUSION: Elevated ALT and reduction of sleep hours may be associated with development of the metabolic syndrome in workers who change their type of job.

Adult↗

PubMed2004

Induction of centrosome amplification and chromosome instability in p53-null cells by transient exposure to subtoxic levels of S-phase-targeting anticancer drugs.

Chromosome instability (CIN) is one of the most important phenotypes in tumor progression, introducing multiple mutations required for acquisition of further malignant characteristics. Abnormal amplification of centrosomes, which is frequently observed in human cancer, has been shown to contribute to CIN by increasing the frequency of mitotic defects. Here, we show that transient exposure to subtoxic concentrations of commonly used anticancer drugs that target DNA synthesis induces centrosome amplification in cells lacking p53 tumor suppressor protein, by allowing continuous centrosome duplication in the absence of DNA synthesis. When these cells are released from cell cycle arrest by removal of drugs, cells suffer extensive destabilization of chromosomes. Considering that p53 is the most frequently mutated gene in human cancer and that CIN is known to be associated with acquisition of malignant phenotypes, our observations may explain why recurrent tumors, after chemotherapy, often exhibit more malignant characteristics than the original tumors. The tumor cells that are exposed to subtoxic levels of DNA synthesis-targeting drugs will be arrested and undergo centrosome amplification. Upon cessation of chemotherapy, these cells will re-enter cell cycling, and experience extensive CIN due to the presence of amplified centrosomes. This in turn promotes generation of tumor cells equipped with further malignant characteristics.

Antineoplastic Agents↗

PubMed2004

Induction of centrosome amplification and chromosome instability in human bladder cancer cells by p53 mutation and cyclin E overexpression.

Centrosome amplification frequently occurs in human cancers and is a major cause of chromosome instability (CIN). In mouse cells, centrosome amplification can be readily induced by loss or mutational inactivation of p53. In human cells, however, silencing of endogenous p53 alone does not induce centrosome amplification or CIN, although high degrees of correlation between p53 mutation and CIN/centrosome amplification in human cancer can be detected, suggesting the presence of additional regulatory mechanism(s) in human cells that ensures the numeral integrity of centrosomes and genomic integrity. Cyclin E, a regulatory subunit for CDK2 that plays a key role in centrosome duplication, frequently is overexpressed in human cancers. We found that cyclin E overexpression, together with loss of p53, efficiently induces centrosome amplification and CIN in human bladder cancer cells but not by either cyclin E overexpression or loss of p53 alone. We extended these findings to bladder cancer specimens and found that centrosome amplification is strongly correlated with concomitant occurrence of cyclin E overexpression and p53 inactivation but not with either cyclin E overexpression or p53 inactivation alone. Because cyclin E expression is strictly controlled in human cells compared with mouse cells, our findings suggest that this stringent regulation of cyclin E expression plays an additional role underlying numeral homeostasis of centrosomes in human cells and that deregulation of cyclin E expression, together with inactivation of p53, results in centrosome amplification.

Aged↗

PubMed2004

[Measuring workplace climate: reliability and validity of the 12-item Organizational Climate Scale (OCS-12)].

In order to investigate the reliability and validity of the short version of the 30-item Organizational Climate Scale (OCS-30; Toshima and Matsuda, 1992, 1995), a self-administered questionnaire was conducted in a sample of 819 employees of two medium-sized private companies in Japan by using the OCS-30, the Generic Job Stress Questionnaire (GJSQ), and the 12-item General Health Questionnaire (GHQ-12). The OCS has two subscales, i.e., the Tradition Scale (TS) and the Organizational Environment Scale (OES). The organizational climate perceived by each worker can be grouped into four categories based on the subscale scores: low TS and high OES (Active), high TS and high OES (Governed), low TS and low OES (Disorganized), and high TS and low OES (Reluctant). Principal component analysis for the OCS-30 was submitted (varimax rotation, the number of factors = 2), and 6 items for each factor, with factor loadings greater than 0.50, were selected for the short version, which constituted the 12-item Organizational Climate Scale (OCS-12). Cronbach's alpha reliability coefficients of the two subscales of the OCS-12 were acceptable; 0.63 for the TS and 0.71 for the OES. Both two subscales of the OCS-12 were significantly correlated with the GHQ-12 and many subscales of the GJSQ, which indicated the good constructive validity of the OCS-12. Among 4 types of organizational climate categorized by the OCS-12, the "Active" group showed the lowest job stress scores. It is suggested that the OCS-12 could be a reliable and valid instrument for assessing workers' perception of workplace climate.

Adult↗

PubMed2003

Functional proteomic analysis of melanoma progression.

Functional proteomics provides a powerful approach to screen for alterations in protein expression and posttranslational modifications under conditions of human disease. In this study, we use protein screening to examine markers of melanoma progression, by profiling melanocyte versus melanoma cell lines using two-dimensional electrophoresis and mass spectrometry. Eight candidate markers were identified as differentially regulated in transformed cells. In particular, hepatoma-derived growth factor (HDGF) and nucleophosmin B23 were strongly correlated with melanoma. Nucleophosmin B23 is a nucleolar and centrosome-associated protein, which has been implicated as a target for cyclin E/cyclin-dependent kinase 2 (CDK2) in modulating centrosome duplication and cell cycle control. Western blotting of one-dimensional and two-dimensional gels showed that the form of nucleophosmin B23 that is up-regulated in melanoma represents a posttranslationally modified form, most likely reflecting enhanced phosphorylation in the tumor-derived cells. In contrast, Western analysis of HDGF demonstrated increased expression of all forms in melanoma cell lines compared with melanocytes. Immunohistochemical analysis of human tissue biopsies showed strong expression of HDGF in early and late stage melanomas and low expression in melanocytes and nontumorigenic nevi. Interestingly, biopsies of nevi showed a graded effect in which HDGF immunoreactivity was reduced in nevoid nests penetrating deep into the dermis compared with nests at the epidermal-dermal junction, suggesting that HDGF expression in nevi is dependent on epidermal cell interactions. In contrast, biopsies of melanoma showed strong expression of HDGF throughout the tumor, including cells located deeply within dermis. Thus, expression of this antigen likely reports a reduced dependence of protein expression on epidermal interactions.

Biomarkers, Tumor↗

PubMed2003

Inactivation of E2F3 results in centrosome amplification.

The E2F family of transcription factors is critical for the control of cell cycle progression. We now show that the specific inactivation of E2F3 in mouse embryo fibroblasts (MEFs) results in a disruption of the centrosome duplication cycle. Loss of E2F3, but not E2F1, E2F2, E2F4, or E2F5 results in unregulated cyclin E-dependent kinase activity, defects in nucleophosmin B association with centrosomes, and premature centriole separation and duplication. Consequently, this defect leads to centrosome amplification, mitotic spindle defects, and aneuploidy. Our findings implicate the E2F3 transcription factor as an important link that orchestrates DNA and centrosome duplication cycles, ensuring the faithful transmission of genetic material to daughter cells.

Aneuploidy↗