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

The primary care diagnosis of dementia in Europe: an analysis using multidisciplinary, multinational expert groups.

Contains fulltext : 70685.pdf (publisher's version ) (Closed access)OBJECTIVES: To explore the extent of variation in the detection of dementia in primary care across Europe, and the potential for the development of European guidelines. METHOD: A mixture of focus group and adapted nominal group methods involving 23 experts of different disciplines and from eight European countries. RESULTS: The diagnosis of dementia should be 'timely' rather than 'early'. Timeliness has an impact on the patient, on the caregiver, on healthcare professionals, and on society. Ethical and moral issues may interfere with the aim of timely diagnosis. Guidelines may be important for facilitating a timely diagnosis of dementia, but were infrequently used and not even available in three of the eight countries. Referral pathways often depended on health care system characteristics, differing throughout the eight European countries, whilst diagnostic strategies differed due to varied cultural influences. There was consensus that national variations can be reduced and timely diagnosis enhanced by combining simple tests using a systematic stepwise case-finding strategy, in conjunction with a strong infrastructure of multidisciplinary collaboration. CONCLUSIONS: This study identified three key themes that should be considered in harmonizing European approaches to the diagnosis of dementia in primary care: (1) a focus on timely diagnosis, (2) the need for the development and implementation of guidelines, and (3) the identification of appropriate referral pathways and diagnostic strategies including multi-professional collaboration. The content of guidelines may be determined by the perspectives of the guideline developers

What happens to anxiety disorders in later life?

Anxiety disorders decline in prevalence with advancing age but remain more common than depressive disorders. They are often of late-onset and there is frequent comorbidity with depressive disorders and physical illness. While anxiety disorders in older people are likely to respond to the same non-pharmacological interventions that have been shown to work in younger people, there is currently little formal evidence of this. Although there is some evidence that the non-benzodiazepine anxiolytic medication, buspirone, is effective against late life anxiety symptoms, clinical trials in older people with rigorously diagnosed anxiety disorders are needed. An anxiety scale with demonstrated reliability and validity in older people is needed for screening for pathological anxiety and for measuring change in older patients undergoing treatment for anxiety disorders