Inhibition of Proteasomal Degradation of Rpn4 Impairs Nonhomologous End-Joining Repair of DNA Double-Strand Breaks

BACKGROUND: The proteasome homeostasis in Saccharomyces cerevisiae is regulated by a negative feedback circuit in which the transcription factor Rpn4 induces the proteasome genes and is rapidly degraded by the assembled proteasome. The integrity of the Rpn4-proteasome feedback loop is critical for cell viability under stressed conditions. We have demonstrated that inhibition of Rpn4 degradation sensitizes cells to DNA damage, particularly in response to high doses of DNA damaging agents. The underlying mechanism, however, remains unclear. METHODOLOGY/PRINCIPAL FINDINGS: Using yeast genetics and biochemical approach we show that inhibition of Rpn4 degradation displays a synthetic growth defect with deletion of the MEC1 checkpoint gene and sensitizes several checkpoint mutants to DNA damage. In addition, inhibition of Rpn4 degradation leads to a defect in repair of double-strand breaks (DSBs) by nonhomologous end-joining (NHEJ). The expression levels of several key NHEJ genes are downregulated and the recruitment of Yku70 to a DSB is reduced by inhibition of Rpn4 degradation. We find that Rpn4 and the proteasome are recruited to a DSB, suggesting their direct participation in NHEJ. Inhibition of Rpn4 degradation may result in a concomitant delay of release of Rpn4 and the proteasome from a DSB. CONCLUSION/SIGNIFICANCE: This study provides the first evidence for the role of proteasomal degradation of Rpn4 in NHEJ

The CCAAT box-binding transcription factor NF-Y regulates basal expression of human proteasome genes

AbstractProtein degradation by the proteasome plays an important role in all major cellular pathways. Aberrant proteasome activity is associated with numerous human diseases including cancer and neurological disorders, but the underlying mechanism is virtually unclear. At least part of the reason for this is due to lack of understanding of the regulation of human proteasome genes. In this study, we found that a large set of human proteasome genes carry the CCAAT box in their promoters. We further demonstrated that the basal expression of these CCAAT box-containing proteasome genes is regulated by the transcription factor NF-Y. Knockdown of NF-YA, an essential subunit of NF-Y, reduced proteasome gene expression and compromised the cellular proteasome activity. In addition, we showed that knockdown of NF-YA sensitized breast cancer cells to the proteasome inhibitor MG132. This study unveils a new role for NF-Y in the regulation of human proteasome genes and suggests that NF-Y may be a potential target for cancer therapy

Treatment of Unruptured Vertebral Artery Aneurysm Involving Posterior Inferior Cerebellar Artery With Pipeline Embolization Device

Background: Treatment of unruptured vertebral artery aneurysm involving posterior inferior cerebellar artery (PICA) is challenging. The experience of pipeline embolization device (PED) therapy for these lesions is still limited.Objective: To evaluate the safety and efficacy of the PED for unruptured vertebral artery aneurysm involving PICA.Methods: Thirty-two patients with unruptured vertebral artery aneurysm involving PICA underwent treatment with PED were retrospectively identified. Procedure-related complications, PICA patency, clinical, and angiographic outcomes were analyzed.Results: Thirty-two aneurysms were successfully treated without any procedure-related complications. Images were available in 30 patients (93.8%) during a period of 3–26 months follow-up (average 8.4 months), which confirmed complete occlusion in 17 patients (56.5%), near-complete occlusion in 9 patients (30%), and incomplete occlusion in one patient (3.3%). Parent artery occlusion (PAO) was occurred in 3 patients (10%). Twenty-eight of 30 PICA remained patent. The two occlusions of PICA were secondary to PAO. At a mean of 20.7 months (range 7–50 months) clinical follow-up, all the patients achieved a favorable outcome without any new neurological deficit.Conclusion: PED seems to be a safe and effective alternative endovascular option for patients with unruptured vertebral artery aneurysm involving PICA

Effects of FBXW7α on Expression and Localization of Heat Shock Transcription Factor 1 in Colorectal Cancer Cells

Objective To investigate the effect of FBXW7 on the expression and localization of HSF1 in colorectal cancer cells. Methods The expression levels of HSF1 and pHSF1Ser326 protein in FBXW7 deletion (KO) and wild-type (WT) FBXW7-expressing counterpart colorectal cancer cells were detected by Western blot. The nucleoprotein expression and localization of pHSF1Ser326 in heat-shocked or recovery stage cells were observed by Western blot and immunofluorescence method. Results The HSF1 expression level in DLD1 cells transfected with FBXW7α was decreased significantly (P < 0.01). The expression levels of HSF1 and pHSF1Ser326 protein in FBXW7 KO cells were higher than those in WT cells (all P < 0.05). HSF1 and pHSF1Ser326 in FBXW7 KO cells were mainly expressed in nucleus and weakly expressed in cytoplasm. After warm stimulation, the expression of HSF1 and pHSF1Ser326 in WT cells recovered to the unstimulated level, while the expression of HSF1 and pHSF1Ser326 in FBXW7 KO cells were higher in the nucleus (all P < 0.01). Conclusion Loss of FBXW7 could affect the nuclear HSF1 recovery after warm stimulation. It may be associated with FBXW7 deletion inhibiting the degradation of nuclear HSF1

Role-based intelligent application state computing for OpenFlow distributed controllers in software-defined networking.

Software-defined networking, in which a network is programmable and controlled with soft computing techniques, is widely used in various network testbeds. To satisfy the demands of large networks, control planes are constructed with distributed controllers, which are a routine aspect of OpenFlow research. Distributed controllers are scalable and fault tolerant; thus, they can replace centralized controllers in large-scale networks. In the foreseeable future, there will emerge more applications based on soft computing techniques. Because there is scant research on application management, a distributed controller with a role-based mechanism for properly managing applications and their states based on their properties has yet to be developed. Thus, in this study, we propose a systematic approach for classifying applications according to their roles to dynamically deploy applications and their states. Both applications and their states are managed based on their properties, including CPU, memory and network bandwidth. This intelligent mechanism, which computes the overhead of applications, provides a compromise between storage and bandwidth usage in OpenFlow distributed controllers. We propose a hierarchical system to differentiate applications and design a controller module for dynamically determining the status of an application

Volumetric measurement of root resorption following molar mini-screw implant intrusion using cone beam computed tomography

OBJECTIVE: Molar intrusion by mini-screw implantation can cause different degrees of root resorption. However, most methods (2-D and 3-D) used for evaluating root resorption have focused on the root length without considering 3-D resorption. The purpose of this study was to volumetrically evaluate root resorption using cone beam computed tomography(CBCT) after mini-screw implant intrusion.\ud \ud MATERIALS AND METHODS: 1. The volumes of 32 teeth were measured using CBCT and laser scanning to verify the accuracy of CBCT. 2. Twelve overerupted molars from adult patients were investigated in this study. After mini-screw implants were inserted into the buccal and palatal alveolar bones, 150 g of force was applied to the mini-screw implants on each side to intrude the molars. CBCT images of all patients were taken immediately prior to intrusion and after intrusion. The volumes of the roots were calculated using the Mimics software program. The differences between the pre-intrusion and post-intrusion root volumes were statistically evaluated with a paired-samples t-test. In addition, the losses of the roots were statistically compared with each other using one-way analysis of variance at the P<0.05 level.\ud \ud RESULTS: No statistically significant volume differences were observed between the physical (laser scanning) and CBCT measurements (P>0.05). The overerupted molars were significantly intruded (P<0.05), and the average intrusion was 3.30±1.60 mm. The differences between the pre-intrusion and post-intrusion root volumes were statistically significant for all of the roots investigated (P<0.05). The roots were sorted by volume loss in descending order as follows: mesiobuccal, palatal, and distobuccal. Statistical significance was achieved among the three roots. The average total resorption for each tooth was 58.39±1.54 mm³.\ud \ud CONCLUSION: Volume measurement using CBCT was able to effectively evaluate root resorption caused by mini-screw intrusion. The highest volume loss was observed in the mesiobuccal root among the three roots of the investigated first molar teeth

Adjustment of first molar for 3D orientation.

<p>Adjustment of first molar for 3D orientation.</p

Reference plane for measurement.

<p>A. Front view of reference plane; B. Skull base view of reference plane, and three points were identified to ensure the reference plane: a, midpoint of the left greater palatine foramen; b, midpoint of the right greater palatine foramen; c, the forefront of the nasal crest.</p