mTOR controls cell growth, in part by regulating p70 S6 kinase alpha (p70alpha) and eukaryotic initiation factor 4E binding protein 1 (4EBP1). Raptor is a 150 kDa mTOR binding protein that also binds 4EBP1 and p70alpha. The binding of raptor to mTOR is necessary for the mTOR-catalyzed phosphorylation of 4EBP1 in vitro, and it strongly enhances the mTOR kinase activity toward p70alpha. Rapamycin or amino acid withdrawal increases, whereas insulin strongly inhibits, the recovery of 4EBP1 and raptor on 7-methyl-GTP Sepharose. Partial inhibition of raptor expression by RNA interference (RNAi) reduces mTOR-catalyzed 4EBP1 phosphorylation in vitro. RNAi of C. elegans raptor yields an array of phenotypes that closely resemble those produced by inactivation of Ce-TOR. Thus, raptor is an essential scaffold for the mTOR-catalyzed phosphorylation of 4EBP1 and mediates TOR action in vivo.

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SummaryThe aim of this study was to investigate the usage of tooth autotransplantation in dental clinics which offer the treatment and evaluate its practicality. Participating dentists were requested to provide information on transplantations they had undertaken from 1 January 1990 to 31 December 2010. A total of 614 teeth from 552 patients (37 dentists) ranging in age from 17 to 79 (mean age: 44.1) were examined. Cumulative survival rate and mean survival time were calculated using the Kaplan-Meier method, and log rank test was used for analysis of factors. The mean number of autotransplantation patients per clinic per year was 1.4. Upper third molars constituted 36.8% of donor teeth, while 37.1% were lower third molars. The lower first molar region was the most common recipient site at 32.6%, followed by the lower second molar region (28.0%). Prosthodontic treatment of transplanted teeth involved coverage with a single crown (72.5%) and abutment of bridge (18.9%). A total of 102 transplanted teeth were lost due to complications such as attachment loss (54.9%) and root resorption (25.7%).The cumulative survival rate in cases where donor teeth had complete root formation was 90.1% at 5 years, 70.5% at 10 years and 55.6% at 15 years. The mean survival time was 165.6 months. Older age was a significant risk factor (p<0.05) for survival. In cases where suitable donor teeth are available, autotransplantation of teeth may be a plausible treatment option for dealing with missing teeth in dental clinics.2

These results indicate that we need to pay more attention to maintaining vital teeth while being aware of the particular tooth types in which VRF most frequently occurs.