Structures and mechanisms of actin ATP hydrolysis

The major cytoskeleton protein actin undergoes cyclic transitions between the monomeric G-form and the filamentous F-form, which drive organelle transport and cell motility. This mechanical work is driven by the ATPase activity at the catalytic site in the F-form. For deeper understanding of the actin cellular functions, the reaction mechanism must be elucidated. Here, we show that a single actin molecule is trapped in the F-form by fragmin domain-1 binding and present their crystal structures in the ATP analog-, ADP-Pi-, and ADP-bound forms, at 1.15-Å resolutions. The G-to-F conformational transition shifts the side chains of Gln137 and His161, which relocate four water molecules including W1 (attacking water) and W2 (helping water) to facilitate the hydrolysis. By applying quantum mechanics/molecular mechanics calculations to the structures, we have revealed a consistent and comprehensive reaction path of ATP hydrolysis by the F-form actin. The reaction path consists of four steps: 1) W1 and W2 rotations; 2) PG–O3B bond cleavage; 3) four concomitant events: W1–PO3− formation, OH− and proton cleavage, nucleophilic attack by the OH− against PG, and the abstracted proton transfer; and 4) proton relocation that stabilizes the ADP-Pi–bound F-form actin. The mechanism explains the slow rate of ATP hydrolysis by actin and the irreversibility of the hydrolysis reaction. While the catalytic strategy of actin ATP hydrolysis is essentially the same as those of motor proteins like myosin, the process after the hydrolysis is distinct and discussed in terms of Pi release, F-form destabilization, and global conformational changes

Constitutive Phosphorylation of Aurora-A on Ser51 Induces Its Stabilization and Consequent Overexpression in Cancer

The serine/threonine kinase Aurora-A (Aur-A) is a proto-oncoprotein overexpressed in a wide range of human cancers. Overexpression of Aur-A is thought to be caused by gene amplification or mRNA overexpression. However, recent evidence revealed that the discrepancies between amplification of Aur-A and overexpression rates of Aur-A mRNA were observed in breast cancer, gastric cancer, hepatocellular carcinoma, and ovarian cancer. We found that aggressive head and neck cancers exhibited overexpression and stabilization of Aur-A protein without gene amplification or mRNA overexpression. Here we tested the hypothesis that aberration of the protein destruction system induces accumulation and consequently overexpression of Aur-A in cancer.Aur-A protein was ubiquitinylated by APC(Cdh1) and consequently degraded when cells exited mitosis, and phosphorylation of Aur-A on Ser51 was observed during mitosis. Phosphorylation of Aur-A on Ser51 inhibited its APC(Cdh1)-mediated ubiquitylation and consequent degradation. Interestingly, constitutive phosphorylation on Ser51 was observed in head and neck cancer cells with protein overexpression and stabilization. Indeed, phosphorylation on Ser51 was observed in head and neck cancer tissues with Aur-A protein overexpression. Moreover, an Aur-A Ser51 phospho-mimetic mutant displayed stabilization of protein during cell cycle progression and enhanced ability to cell transformation.Broadly, this study identifies a new mode of Aur-A overexpression in cancer through phosphorylation-dependent inhibition of its proteolysis in addition to gene amplification and mRNA overexpression. We suggest that the inhibition of Aur-A phosphorylation can represent a novel way to decrease Aur-A levels in cancer therapy

'Flowers Will Bloom': Assessing Support for Survivors of Japan's 3/11 Disaster through the Charity Song

Objective: NHK, Japan’s public broadcast network, produced a theme song in March 2012 to promote public support for survivors of the 3/11 disaster of 2011. The objective of this study is to evaluate how and to what extent this charity song Hana wa Saku (“Flowers Will Bloom”) has contributed to assisting survivors of the disaster.Methods: First, the song’s characteristics are considered in two categories, (1) the way the original Japanese recording was conducted, and (2) the song itself. Then, the effects on the survivors are assessed through analyzing the actual ways the song was performed and their repercussions covered by the media.Results: (1) Along with the composer and the lyricist, all singers (thirty-six celebrities) of the original Japanese recording had strong personal links to the region affected by the disaster. In the video-clip performance, each singer relays a phrase of the song, holding a gerbera daisy instead of a baton. This performance has left a lasting impression of connectedness specifically between the survivors and the victims.(2) According to lyricist IWAI Shunji, the song’s words represent “a message from those who lost their lives to the people they left behind.” Repeatedly listening to the fictional messages of their loved ones in heaven, through the voices of the living people trying to provide comfort, have particularly helped young survivors bounce back from their sufferings.Conclusion: Responding to NHK’s call, more than 10,000 people have posted their amateur performances of the song on the official website by May 2013. All royalties and other proceeds of the song are being donated for recovery efforts for the affected region (28,907,109 yen as of March 2013). Findings demonstrate that, despite differences in its impact among survivors, this charity song can be an effective and accessible means to foster public support for the survivors

Impact of 1.0 mg/Day Dienogest Treatment on Bone Metabolism Markers in Young Women with Dysmenorrhea

A low dose of dienogest (DNG) 1 mg/day is useful for treating dysmenorrhea in young women. However, the effect of DNG on bone turnover during bone growth and formation, rather than at maturity, is currently unknown even at low doses. We investigated change in bone turnover after 3 months of DNG 1 mg/day. This retrospective cohort study included young women aged 10–24 years with dysmenorrhea and irregular menstruation. Gonadotropins and the bone metabolism markers TRACP-5b and BAP were compared before and at 3 months after administration of DNG 1 mg/day. There were no significant changes in TRACP-5b (before, 455.6 ± 323.6 mU/dL; 3 months after, 462.1 ± 346.1 mU/dL), BAP (before, 24.7 ± 19.0 μg/L; 3 months after, 25.2 ± 22.3 μg/L), or the TRACP-5b/BAP ratio (before, 22.1 ± 7.0; 3 months after, 21.5 ± 6.3). Administration of DNG 1 mg/day had no significant effect on bone turnover after 3 months during the bone-growth phase in young women

Legal aspects of transborder data flows and protection of privacy : contemporary developments in establishing legal regimes over a rapidly emerging field of telematics

The purpose of this thesis is to clarify what the international regulatory techniques governing Transborder Data Flows (TDF) should be. This thesis deals mainly with the concepts and implementation of rules relating to the protection of privacy and transborder flows of personal data, as adopted by two international organizations, namely the OECD and the Council of Europe. The focus of this study is on the influence of two instruments adopted in 1980 (namely the OECD Guidelines and the CoE Convention), on the national data protection policies of the member states. A further section is devoted to reviewing their impact on Japanese public and private sectors.Employing the findings arising from the activities of these two organizations, the concluding chapter links the theoretical and empirical components of the study to indicate certain conditions necessary for establishing an effective legal regime over a rapidly emerging field of telematics

Cost-effectiveness of the recommended medical intervention for the treatment of dysmenorrhea and endometriosis in Japan

Abstract Background and objective This study aims to assess the cost-effectiveness of early physician consultation and guideline-based intervention to prevent endometriosis and/or disease progression using oral contraceptive (OC) and progestin compared to follow-up of self-care for dysmenorrhea in Japan. Methods A yearly-transmitted Markov model of five major health states with four sub-medical states was constructed. Transition probabilities among health and medical states were derived from Japanese epidemiological patient surveys and converted to appropriate parameters for inputting into the model. The dysmenorrhea and endometriosis-associated direct costs included inpatient, outpatient visit, surgery, and medication (OC agents, over-the-counter drugs), etc. The utility measure for patients with phase I–IV endometriosis comprised a visual analogue scale. We estimated the cost per quality-adjusted life year (QALY) at a time horizon of 23 years. An annual discount rate at 3% for both cost and outcome was considered. Results The base case outcomes indicated that the intervention would be more cost-effective than self-care, as the incremental cost-effectiveness ratio (ICER) yielded 115,000 JPY per QALY gained from the healthcare payers’ perspective and the societal monetary value (SMV) was approximately positive 3,130,000 JPY, favoring the intervention in the cost–benefit estimate. A tornado diagram depicting the stochastic sensitivity analysis of the ICER and SMV from both the healthcare payers’ and societal perspectives confirmed the robustness of the base case. A probabilistic analysis resulting from 10,000-time Monte Carlo simulations demonstrated efficiency at willingness-to-pay thresholds in more than 90% of the iterations. Conclusions The present analysis demonstrated that early physician consultation and guideline-based intervention would be more cost-effective than self-care in preventing endometriosis and/or disease progression for patients with dysmenorrhea in Japan