Probing Molecular Mechanisms of the Hsp90 Chaperone: Biophysical Modeling Identifies Key Regulators of Functional Dynamics

Deciphering functional mechanisms of the Hsp90 chaperone machinery is an important objective in cancer biology aiming to facilitate discovery of targeted anti-cancer therapies. Despite significant advances in understanding structure and function of molecular chaperones, organizing molecular principles that control the relationship between conformational diversity and functional mechanisms of the Hsp90 activity lack a sufficient quantitative characterization. We combined molecular dynamics simulations, principal component analysis, the energy landscape model and structure-functional analysis of Hsp90 regulatory interactions to systematically investigate functional dynamics of the molecular chaperone. This approach has identified a network of conserved regions common to the Hsp90 chaperones that could play a universal role in coordinating functional dynamics, principal collective motions and allosteric signaling of Hsp90. We have found that these functional motifs may be utilized by the molecular chaperone machinery to act collectively as central regulators of Hsp90 dynamics and activity, including the inter-domain communications, control of ATP hydrolysis, and protein client binding. These findings have provided support to a long-standing assertion that allosteric regulation and catalysis may have emerged via common evolutionary routes. The interaction networks regulating functional motions of Hsp90 may be determined by the inherent structural architecture of the molecular chaperone. At the same time, the thermodynamics-based “conformational selection” of functional states is likely to be activated based on the nature of the binding partner. This mechanistic model of Hsp90 dynamics and function is consistent with the notion that allosteric networks orchestrating cooperative protein motions can be formed by evolutionary conserved and sparsely connected residue clusters. Hence, allosteric signaling through a small network of distantly connected residue clusters may be a rather general functional requirement encoded across molecular chaperones. The obtained insights may be useful in guiding discovery of allosteric Hsp90 inhibitors targeting protein interfaces with co-chaperones and protein binding clients

The use of mesenchymal stem cells for cartilage repair and regeneration: a systematic review.

BACKGROUND: The management of articular cartilage defects presents many clinical challenges due to its avascular, aneural and alymphatic nature. Bone marrow stimulation techniques, such as microfracture, are the most frequently used method in clinical practice however the resulting mixed fibrocartilage tissue which is inferior to native hyaline cartilage. Other methods have shown promise but are far from perfect. There is an unmet need and growing interest in regenerative medicine and tissue engineering to improve the outcome for patients requiring cartilage repair. Many published reviews on cartilage repair only list human clinical trials, underestimating the wealth of basic sciences and animal studies that are precursors to future research. We therefore set out to perform a systematic review of the literature to assess the translation of stem cell therapy to explore what research had been carried out at each of the stages of translation from bench-top (in vitro), animal (pre-clinical) and human studies (clinical) and assemble an evidence-based cascade for the responsible introduction of stem cell therapy for cartilage defects. This review was conducted in accordance to PRISMA guidelines using CINHAL, MEDLINE, EMBASE, Scopus and Web of Knowledge databases from 1st January 1900 to 30th June 2015. In total, there were 2880 studies identified of which 252 studies were included for analysis (100 articles for in vitro studies, 111 studies for animal studies; and 31 studies for human studies). There was a huge variance in cell source in pre-clinical studies both of terms of animal used, location of harvest (fat, marrow, blood or synovium) and allogeneicity. The use of scaffolds, growth factors, number of cell passages and number of cells used was hugely heterogeneous. SHORT CONCLUSIONS: This review offers a comprehensive assessment of the evidence behind the translation of basic science to the clinical practice of cartilage repair. It has revealed a lack of connectivity between the in vitro, pre-clinical and human data and a patchwork quilt of synergistic evidence. Drivers for progress in this space are largely driven by patient demand, surgeon inquisition and a regulatory framework that is learning at the same pace as new developments take place

Influence of N-butylscopolamine on SUV in FDG PET of the bowel

“The original publication is available at www.springerlink.com”. Copyright Springer. [Full text of this article is not available in the UHRA]Objectives Peristalsis can lead to confusing FDG PET bowel uptake artefacts and potential for recording inaccurate mean standardised uptake value (SUV) measurements in PET-CT scans. Accordingly, we investigate the influence of different SUV normalisations on FDG PET uptake of the bowel and assess which one(s) have least dependence on body size factors in patients with and without the introduction of the anti-peristalsis agent N-butylscopolamine (Buscopan). Methods This study consisted of 92 prospective oncology patients, each having a whole body 18F-FDG PET scan. Correlations were investigated between height, weight, glucose, body mass index (bmi), lean body mass (lbm) and body surface area (bsa) with maximum and mean SUV recorded for bowel normalised to weight (SUVw), lbm (SUVlbm), bsa (SUVbsa) and blood glucose corrected versions (SUVwg, SUVlbmg, SUVbsag). Results Standardised uptake value normalisations were significantly different between control and Buscopan groups with less variability experienced within individual SUV normalisations by the administration of Buscopan. Mean SUV normalisations accounted for 80% of correlations in the control group and 100% in the Buscopan group. Further, >86% of all correlations across both groups were dominated by mean SUV normalisations of which, about 69% were accounted for by SUVbsa and SUVbsag. Conclusions We recommend avoiding mean SUVbsa and individual glucose normalisations especially, mean SUVbsag as these dominated albeit relatively weak correlations with body size factors in control and Buscopan groups. Mean and maximum SUVw and SUVlbm were shown to be independent of any body size parameters investigated in both groups and therefore considered suitable for monitoring FDG PET uptake in the normal bowel for our patient cohort.Peer reviewe