Drug-tolerant persister cancer cells are vulnerable to GPX4 inhibition.

Acquired drug resistance prevents cancer therapies from achieving stable and complete responses. Emerging evidence implicates a key role for non-mutational drug resistance mechanisms underlying the survival of residual cancer 'persister' cells. The persister cell pool constitutes a reservoir from which drug-resistant tumours may emerge. Targeting persister cells therefore presents a therapeutic opportunity to impede tumour relapse. We previously found that cancer cells in a high mesenchymal therapy-resistant cell state are dependent on the lipid hydroperoxidase GPX4 for survival. Here we show that a similar therapy-resistant cell state underlies the behaviour of persister cells derived from a wide range of cancers and drug treatments. Consequently, we demonstrate that persister cells acquire a dependency on GPX4. Loss of GPX4 function results in selective persister cell ferroptotic death in vitro and prevents tumour relapse in mice. These findings suggest that targeting of GPX4 may represent a therapeutic strategy to prevent acquired drug resistance

Room-Temperature Distance Measurements of Immobilized Spin-Labeled Protein by DEER/PELDOR

Nitroxide spin labels are used for double electron-electron resonance (DEER) measurements of distances between sites in biomolecules. Rotation of gem-dimethyls in commonly used nitroxides causes spin echo dephasing times (Tm) to be too short to perform DEER measurements at temperatures between ∼80 and 295 K, even in immobilized samples. A spirocyclohexyl spin label has been prepared that has longer Tm between 80 and 295 K in immobilized samples than conventional labels. Two of the spirocyclohexyl labels were attached to sites on T4 lysozyme introduced by site-directed spin labeling. Interspin distances up to ∼4 nm were measured by DEER at temperatures up to 160 K in water/glycerol glasses. In a glassy trehalose matrix the Tm for the doubly labeled T4 lysozyme was long enough to measure an interspin distance of 3.2 nm at 295 K, which could not be measured for the same protein labeled with the conventional 1-oxyl-2,2,5,5-tetramethyl-3-pyrroline-3- (methyl)methanethio-sulfonate label

Room-Temperature Distance Measurements of Immobilized Spin-Labeled Protein by DEER/PELDOR

Nitroxide spin labels are used for double electron-electron resonance (DEER) measurements of distances between sites in biomolecules. Rotation of gem-dimethyls in commonly used nitroxides causes spin echo dephasing times (Tm) to be too short to perform DEER measurements at temperatures between ∼80 and 295 K, even in immobilized samples. A spirocyclohexyl spin label has been prepared that has longer Tm between 80 and 295 K in immobilized samples than conventional labels. Two of the spirocyclohexyl labels were attached to sites on T4 lysozyme introduced by site-directed spin labeling. Interspin distances up to ∼4 nm were measured by DEER at temperatures up to 160 K in water/glycerol glasses. In a glassy trehalose matrix the Tm for the doubly labeled T4 lysozyme was long enough to measure an interspin distance of 3.2 nm at 295 K, which could not be measured for the same protein labeled with the conventional 1-oxyl-2,2,5,5-tetramethyl-3-pyrroline-3- (methyl)methanethio-sulfonate label

Loss of BMPR2 Expression in Skeletal Progenitor Cells Reduces Age-Related Bone Loss

Osteoporosis is a disease of low bone mineral density (BMD) that affects 10 million Americans with an additional 34 million at risk for developing the disease. Current FDA-approved therapies for osteoporosis involve anti-resorptive agents but many patients would benefit from augmenting bone formation as well as inhibiting bone loss. We recently reported that targeted deletion of the type 2 BMP receptor BMPR2 using Prx1-Cre in skeletal progenitor cells in mice leads to dramatically increased bone mass and bone formation rate by ten weeks of age in the absence of changes in osteoclast function (Lowery et al 2015). In the present study, we examined the age-related impact of Bmpr2 deletion and found that, consistent with our previous results, both male and female Bmpr2-cKO mice exhibit high bone mass when compared to control mice at 55 weeks of age. We also found that the age-related decline in bone mass from 15 weeks to 55 weeks of age in Bmpr2-cKO mice is reduced approximately three-fold compared to control mice, with male and female Bmpr2-cKO mice losing on average only 18% and 27%, respectively, while male and female control mice lost 55% and 77%, respectively, over the same time span. High bone mass in aged Bmpr2-cKO mice is associated with elevated serum levels of the bone formation marker Procollagen Type I N-terminal Propeptide (P1NP). In contrast, serum levels of the bone resorption marker Collagen Type I C-telopeptide (CTx) are unchanged in Bmpr2-cKO mice. Collectively, these findings indicate that loss of Bmpr2 in skeletal progenitor cells causes a sustained imbalance in bone formation vs. bone resorption and results in high bone mass in the aging skeleton. Our findings suggest that strategies aimed at controlling signaling through BMPR2 have the potential to impact bone mass in the aging adult skeleton

Nutrient Sensing by Tas1R Proteins is Required for Normal Bone Resorption

Current therapies for low bone mass consist of inhibiting osteoclast activity or increasing the PTH or Wnt signaling pathways. These approaches have significant drawbacks that limit their use in specific patient populations and/or negatively impact patient compliance with therapy. Developing improved therapies requires diversifying our understanding of the mechanisms underlying postnatal bone remodeling by examining lesser-known signaling pathways. One such pathway is the taste receptor type 1 (TAS1R) family of heterotrimeric G protein-coupled receptors, which participates in monitoring energy and nutrient status. Previous work reported that global deletion of TAS1R member 3 (TAS1R3), which is a bi-functional protein that recognizes amino acids or sweet molecules when dimerized with TAS1R member 1 (TAS1R1) or TAS1R member 2 (TAS1R2), respectively, leads to increased cortical bone mass. Here, we corroborate the increased thickness of cortical bone in Tas1R3 knockout mice and confirm that Tas1R3 is expressed in the bone environment. Quantification of serum bone turnover markers indicate that this phenotype is likely due to uncoupled bone remodeling, with levels of the bone resorption marker CTx being reduced greater than 60% in Tas1R3 mutant mice; no changes were observed in levels of the bone formation marker PINP. Consistent with this, Tas1R3 and its putative signaling partner Tas1R2 are expressed in primary osteoclasts and RAW264.7 cells following RANKL-mediated differentiation. These findings suggest that osteoclast function and/or differentiation may be altered in the absence of Tas1R3 expression. To test this, we quantified bone-specific expression of Rankl and determined the Rankl:Opg ratio; no differences were observed between control and Tas1R3 knockout mice in these analyses. In vitro studies examining further downstream effectors of TAS1R2:3 in response to saccharin and receptor antagonist gurmarin are currently underway. Collectively, our findings provide the first demonstration that nutrient monitoring by TAS1R3 is essential for normal bone resorption in vivo

Optimizing the number of acoustic emission sensors using the bees algorithm for detecting surface fractures

Non-destructive testing methods have gained popularity as they become more widely available. Although there are several techniques that could be used for this purpose, this paper focuses on acoustic emission sensors for detecting surface fractures and the use of the Bees Algorithm, a swarm-based technique, for optimizing the number of sensors required to reliably detect surface fractures. The paper describes the approach that has been used in this study where the dimension of the surface is specified by the user. The results show that, in theory and through simulation, that the Bees Algorithm is capable of determining the minimum number of sensors needed to locate the surface fracture with an acceptable level of accuracy. The method described could be used for the purpose of optimization in other engineering as well as non-engineering applications

Integrated photonic building blocks for next-generation astronomical instrumentation I: the multimode waveguide

We report on the fabrication and characterization of composite multimode waveguide structures that consist of a stack of single-mode waveguides fabricated by ultrafast laser inscription. We explore 2 types of composite structures; those that consist of overlapping single-mode waveguides which offer the maximum effective index contrast and non overlapped structures which support multiple modes via strong evanescent coupling. We demonstrate that both types of waveguides have negligible propagation losses (to within experimental uncertainty) for light injected with focal ratios >8, which corresponds to the cutoff of the waveguides. We also show that right below cutoff, there is a narrow region where the injected focal ratio is preserved (to within experimental uncertainty) at the output. Finally, we outline the major application of these highly efficient waveguides; in a device that is used to reformat the light in the focal plane of a telescope to a slit, in order to feed a diffraction-limited spectrograph.Comment: 15 pages, 11 figures, accepted to Optics Expres

Towards energetically viable asymmetric deprotonations : selectivity at more elevated temperatures with C2-symmetric magnesium bisamides

A novel chiral magnesium bisamide has enabled the development of effective asymmetric deprotonation protocols at substantially more elevated temperatures. This new, structurally simple, C2-symmetric magnesium complex displays excellent levels of asymmetric efficiency and energy reduction in the synthesis of enantioenriched enol silane

The Relationship between Knee Valgus and Clinical Measures in Professional Basketball: A CART Analysis

Background/Purpose: Lower extremity injuries occur at an amplified rate in professional basketball. Evidence suggests that knee frontal plane valgus may be associated with risk of injury. The Landing Error Scoring System includes the assessment of maximum knee valgus during a countermovement jump. The investigation of interactions among linear and non-linear factors may help the understanding of the interdependence of various measures and poor performance on the knee valgus displacement (KVD) component of the LESS in professional basketball players. The purpose of this study was to investigate predictors of knee valgus displacement on the LESS. We hypothesize that a positive finding on the knee valgus displacement component of the LESS will be predicted by select clinical measures. Methods: 47 professional basketball players participated. Measurements were completed as part of preseason mobility screening prior to the 2015-16 and 2016-17 NBA seasons. Classification and Regression Tree Analysis (CART) were used to investigate linear and non-linear interactions among predictors and their influence on KVD in players who performed the LESS test. Results: Of the 47 players included in this study, 16 players did not test positive for KVD on the LESS test and 31 did. Pruning resulted in 4 splits (r2=0.507) demonstrating that KVD was predicted by total hip rotation range of motion, dominant leg hip external rotation, and standing arch height index measure. Predictive modeling, classified 18 of the 31 players with KVD and 8 of the 16 players who tested negative for KVD. The area under the ROC curve was .9183, suggesting that classification of players using this model was not random. Conclusion: KVD and performance on the LESS has been linked with injury. CART analysis captured linear and non-linear interactions between clinical measures suggesting that lower extremity biomechanical factors may be associated with predicting KVD during performance on the LESS. Clinical Relevance: KVD and the LESS test has been shown to be predictive of injury. Identifying which clinical measures may be linked with poor performance on this test may aide clinicians in determining appropriate interventions that may be associated with improved scores and minimize risk of injury.https://ecommons.udayton.edu/dpt_symposium/1000/thumbnail.jp

Loss of the Nutrient Sensor Tas1R3 Leads to Reduced Bone Resorption

Background: The Taste receptor, type 1 (TAS1R) family of heterotrimeric G protein-coupled receptors participates in monitoring energy and nutrient needs. TAS1R member 3 (TAS1R3) either recognizes amino acids such as glycine and L-glutamate or sweet molecules such as sucrose and fructose when dimerized with TAS1R member 1 (TAS1R1) or TAS1R member 2 (TAS1R2), respectively. Loss of TAS1R3 expression can cause impaired mTORC1 signaling and increased autophagy, indicating that signaling through this receptor is critical for assessing nutrient needs. Recently, it was reported that global deletion of TAS1R3 expression in Tas1R3 mutant mice leads to increased cortical bone mass and trabecular remodeling but the underlying cellular mechanism leading to this phenotype remains unclear. Results: To address this open question, we quantified bone turnover markers in serum from 20-week-old wild type and Tas1R3 mutant mice and found that levels of the resorption marker Collagen Type I C-telopeptide (CTx) were reduced on average by \u3e60% in the absence of TAS1R3 expression. Levels of the bone formation marker Procollagen Type I N-terminal Propeptide (P1NP) tend to be higher in Tas1R3 mutant mice but this finding did not reach statistical significance (