The degradation of p53 and its major E3 ligase Mdm2 is differentially dependent on the proteasomal ubiquitin receptor S5a.

p53 and its major E3 ligase Mdm2 are both ubiquitinated and targeted to the proteasome for degradation. Despite the importance of this in regulating the p53 pathway, little is known about the mechanisms of proteasomal recognition of ubiquitinated p53 and Mdm2. In this study, we show that knockdown of the proteasomal ubiquitin receptor S5a/PSMD4/Rpn10 inhibits p53 protein degradation and results in the accumulation of ubiquitinated p53. Overexpression of a dominant-negative deletion of S5a lacking its ubiquitin-interacting motifs (UIM)s, but which can be incorporated into the proteasome, also causes the stabilization of p53. Furthermore, small-interferring RNA (siRNA) rescue experiments confirm that the UIMs of S5a are required for the maintenance of low p53 levels. These observations indicate that S5a participates in the recognition of ubiquitinated p53 by the proteasome. In contrast, targeting S5a has no effect on the rate of degradation of Mdm2, indicating that proteasomal recognition of Mdm2 can be mediated by an S5a-independent pathway. S5a knockdown results in an increase in the transcriptional activity of p53. The selective stabilization of p53 and not Mdm2 provides a mechanism for p53 activation. Depletion of S5a causes a p53-dependent decrease in cell proliferation, demonstrating that p53 can have a dominant role in the response to targeting S5a. This study provides evidence for alternative pathways of proteasomal recognition of p53 and Mdm2. Differences in recognition by the proteasome could provide a means to modulate the relative stability of p53 and Mdm2 in response to cellular signals. In addition, they could be exploited for p53-activating therapies. This work shows that the degradation of proteins by the proteasome can be selectively dependent on S5a in human cells, and that this selectivity can extend to an E3 ubiquitin ligase and its substrate

Post-operative critical care management of patients undergoing cytoreductive surgery and heated intraperitoneal chemotherapy (HIPEC)

<p>Abstract</p> <p>Background</p> <p>Cytoreductive surgery (CRS) and Heated Intraperitoneal Chemotherapy (HIPEC) results in a number of physiological changes with effects on the cardiovascular system, oxygen consumption and coagulation. The Critical Care interventions required by this cohort of patients have not yet been quantified.</p> <p>Methods</p> <p>This retrospective audit examines the experience of a Specialist Tertiary Centre in England over an 18 month period (January 2009-June 2010) during which 69 patients underwent CRS and HIPEC. All patients were extubated in the operating theatre and transferred to the Critical Care Unit (CCU) for initial post-operative management.</p> <p>Results</p> <p>Patients needed to remain on the CCU for 2.4 days (0.8-7.8). There were no 30 day mortalities. The majority of patients (70.1%) did not require post-operative organ support. 2 patients who developed pneumonia post-operatively required respiratory support. 18 (26.1%) patients required vasopressor support with norepinephrine with a mean duration of 13.94 hours (5-51 hours) and mean dose of 0.04 mcg/kg/min. Post-operative coagulopathy peaked at 24 hours. A significant drop in serum albumin was observed.</p> <p>Conclusion</p> <p>The degree of organ support required post-operatively is minimal. Early extubation is efficacious with the aid of epidural analgesia. Critical Care monitoring for 48 hours is desirable in view of the post-operative challenges.</p

The proteasome inhibitor MG-132 sensitizes PC-3 prostate cancer cells to ionizing radiation by a DNA-PK-independent mechanism

BACKGROUND: By modulating the expression levels of specific signal transduction molecules, the 26S proteasome plays a central role in determining cell cycle progression or arrest and cell survival or death in response to stress stimuli, including ionizing radiation. Inhibition of proteasome function by specific drugs results in cell cycle arrest, apoptosis and radiosensitization of many cancer cell lines. This study investigates whether there is also a concomitant increase in cellular radiosensitivity if proteasome inhibition occurs only transiently before radiation. Further, since proteasome inhibition has been shown to activate caspase-3, which is involved in apoptosis, and caspase-3 can cleave DNA-PKcs, which is involved in DNA-double strand repair, the hypothesis was tested that caspase-3 activation was essential for both apoptosis and radiosensitization following proteasome inhibition. METHODS: Prostate carcinoma PC-3 cells were treated with the reversible proteasome inhibitor MG-132. Cell cycle distribution, apoptosis, caspase-3 activity, DNA-PKcs protein levels and DNA-PK activity were monitored. Radiosensitivity was assessed using a clonogenic assay. RESULTS: Inhibition of proteasome function caused cell cycle arrest and apoptosis but this did not involve early activation of caspase-3. Short-time inhibition of proteasome function also caused radiosensitization but this did not involve a decrease in DNA-PKcs protein levels or DNA-PK activity. CONCLUSION: We conclude that caspase-dependent cleavage of DNA-PKcs during apoptosis does not contribute to the radiosensitizing effects of MG-132

Beyond salty reins – modelling benthic species' spatial response to their physical environment in the Pomeranian Bay (Southern Baltic Sea)

The brackish water environment of the Baltic Sea is dominated by a strong gradient of salinity and along with salinity the benthic diversity decreases – salinity is regarded as the master factor regulating benthic diversity in brackish habitats. In this scheme, consistently small patches of comparatively higher or lower benthic diversity do emerge in areas where either environmental or anthropogenic impacts on the benthic habitat change drastically over short spatial distances. Hence, spatial diversity of ecological factors creates diversity among benthic colonization and community structures. We show through a logistic modeling approach the possibility to predict thereby induced benthic colonization areas and community structures inside the broad scheme of a brackish water habitat. This study bases upon quantitative macrozoobenthic abundance data collected over a period of 4 years. It clearly demonstrates the need to analyze species’ relationships in gradient systems such as the Baltic Sea and provides a tool to predict natural and anthropogenic forced changes in species distribution

Schilddrüsenmetastasen eines Nierenzellkarzinoms - drei Fallvorstellungen und Übersicht der Literatur

Klinisch relevante, isolierte Metastasen eines malignen Tumors in der Schilddrüse stellen eine absolute Rarität dar. Der Primarius findet sich meist in der Niere in Form eines hellzelligen Nierenzellkarzinoms. Eine Besonderheit dieser klinischen Situation ist ein relativ spätes metachrones Auftreten: eine isolierte Schilddrüsenmetastasierung tritt durchschnittlich 100-120 Monate nach Entfernung des Primärtumors auf. Die operative Sanierung sollte angestrebt werden, da nach Resektion solitärer Schilddrüsenmetastasen eines Nierenzellkarzinoms eine 5-Jahres-Überlebensrate von bis zu 50 % erreicht werden kann. Wir berichten über drei Patienten mit operativ entfernten Schilddrüsenmetastasen eines Nierenzellkarzinoms und liefern eine Literaturübersicht zu diesem Thema. Clinically significant, solitary metastasis to the thyroid gland is a rare occurrence. The clear cell carcinoma of the kidney (RCC) is the most common primary tumor site. Late recurrence is a notable feature of renal carcinoma. Solitary metastases in the thyroid gland occur as late as 100-120 months from the date of nephrectomy. There is a clear survival benefit in selected cases if surgical approach to the thyroid metastases is chosen. In those patients who have undergone complete resection, 5-year-survival-rates of 50 % have been reported. We describe 3 cases of surgically treated thyroid metastases of RCC, and review the literature

Meridional and Cross‐Shelf Variability of N2O and CH4 in the Eastern‐South Atlantic

Upward transport and/or mixing of trace gas-enriched subsurface waters fosters the exchange of nitrous oxide (N2O) and methane (CH4) with the atmosphere in the Eastern-South Atlantic (ESA). To date, it is, however, unclear whether this source is maintained by local production or advection of trace gas-enriched water masses. The meridional and zonal variability of N2O and CH4 in the ESA were investigated to identify the contributions of the major regional water masses to the overall budget of N2O and CH4. The maximal sea surface N2O and CH4 concentrations and the main ESA upwelling cells co-occurred with a strong negative correlation with the sea surface temperature (SST) (p < 0.05). The dominance of the central water masses in the winter and spring seasons and the interplay between shelf topography and wind regime are suggested to determine enhanced gas transfer toward the sea-air interface or “capping” at midwater depth. These parameters are supposed to be critical in the local budget of N2O and CH4 in the ESA. Our findings also show that the shape of N2O and CH4 gradients is very similar both meridionally and zonally; however, the extent of the differences between the high-end and low-end members of the concentrations/saturations range is different. This suggests a more pronounced effect of local sources on CH4 than N2O distribution, in particular in the Walvis Bay area. With respect to N2O, however, low-oxygen waters from the poleward undercurrent impinge in the shelf close to Cape Frio and often result in N2O concentrations significantly higher than off Lüderitz (p < 0.05