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Protein oxidation sits at the intersection of multiple signalling pathways, yet the magnitude and extent of crosstalk between oxidation and other post-translational modifications remains unclear. Here, we delineate global changes in adipocyte signalling networks following acute oxidative stress and reveal considerable crosstalk between cysteine oxidation and phosphorylation-based signalling. Oxidation of key regulatory kinases, including Akt, mTOR and AMPK influences the fidelity rather than their absolute activation state, highlighting an unappreciated interplay between these modifications. Mechanistic analysis of the redox regulation of Akt identified two cysteine residues in the pleckstrin homology domain (C60 and C77) to be reversibly oxidized. Oxidation at these sites affected Akt recruitment to the plasma membrane by stabilizing the PIP 3 binding pocket. Our data provide insights into the interplay between oxidative stress-derived redox signalling and protein phosphorylation networks and serve as a resource for understanding the contribution of cellular oxidation to a range of diseases. Crosstalk between protein oxidation and other post-translational modifications remains unexplored. Here, the authors map the phosphoproteome, cysteine redox proteome and total proteome of adipocytes under acute oxidative stress and reveal crosstalk between cysteine oxidation and phosphorylation-based signalling.

Over the years it has been established that SIN1, a key component of mTORC2, could interact with Ras family small GTPases through its Ras-binding domain (RBD). The physical association of Ras and SIN1/mTORC2 could potentially affect both mTORC2 and Ras-ERK pathways. To decipher the precise molecular mechanism of this interaction, we determined the high-resolution structures of HRas/KRas-SIN1 RBD complexes, showing the detailed interaction interface. Mutation of critical interface residues abolished Ras-SIN1 interaction and in SIN1 knockout cells we demonstrated that Ras-SIN1 association promotes SGK1 activity but inhibits insulin-induced ERK activation. With structural comparison and competition fluorescence resonance energy transfer (FRET) assays we showed that HRas-SIN1 RBD association is much weaker than HRas-Raf1 RBD but is slightly stronger than HRas-PI3K RBD interaction, providing a possible explanation for the different outcome of insulin or EGF stimulation. We also found that SIN1 isoform lacking the PH domain binds stronger to Ras than other longer isoforms and the PH domain appears to have an inhibitory effect on Ras-SIN1 binding. In addition, we uncovered a Ras dimerization interface that could be critical for Ras oligomerization. Our results advance our understanding of Ras-SIN1 association and crosstalk between growth factor-stimulated pathways.

The phosphoinositide 3-kinase (PI3K)-Akt network is tightly controlled by feedback mechanisms that regulate signal flow and ensure signal fidelity. A rapid overshoot in insulin-stimulated recruitment of Akt to the plasma membrane has previously been reported, which is indicative of negative feedback operating on acute timescales. Here, we show that Akt itself engages this negative feedback by phosphorylating insulin receptor substrate (IRS) 1 and 2 on a number of residues. Phosphorylation results in the depletion of plasma membrane-localised IRS1/2, reducing the pool available for interaction with the insulin receptor. Together these events limit plasma membrane-associated PI3K and phosphatidylinositol (3,4,5)-trisphosphate (PIP3) synthesis. We identified two Akt-dependent phosphorylation sites in IRS2 at S306 (S303 in mouse) and S577 (S573 in mouse) that are key drivers of this negative feedback. These findings establish a novel mechanism by which the kinase Akt acutely controls PIP3 abundance, through post-translational modification of the IRS scaffold. For the body to work properly, cells must constantly ‘talk’ to each other using signalling molecules. Receiving a chemical signal triggers a series of molecular events in a cell, a so-called ‘signal transduction pathway’ that connects a signal with a precise outcome. Disturbing cell signalling can trigger disease, and strict control mechanisms are therefore in place to ensure that communication does not break down or become erratic. For instance, just as a thermostat turns off the heater once the right temperature is reached, negative feedback mechanisms in cells switch off signal transduction pathways when the desired outcome has been achieved. The hormone insulin is a signal for growth that increases in the body following a meal to promote the storage of excess blood glucose (sugar) in muscle and fat cells. The hormone binds to insulin receptors at the cell surface and switches on a signal transduction pathway that makes the cell take up glucose from the bloodstream. If the signal is not engaged diseases such as diabetes develop. Conversely, if the signal cannot be adequately switched of cancer can develop. Determining exactly how insulin works would help to understand these diseases better and to develop new treatments. Kearney et al. therefore set out to examine the biochemical ‘fail-safes’ that control insulin signalling. Experiments using computer simulations of the insulin signalling pathway revealed a potential new mechanism for negative feedback, which centred on a molecule known as Akt. The models predicted that if the negative feedback were removed, then Akt would become hyperactive and accumulate at the cell’s surface after stimulation with insulin. Further manipulation of the ‘virtual’ insulin signalling pathway and studies of live cells in culture confirmed that this was indeed the case. The cell biology experiments also showed how Akt, once at the cell surface, was able to engage the negative feedback and shut down further insulin signalling. Akt did this by inactivating a protein required to pass the signal from the insulin receptor to the rest of the cell. Overall, this work helps to understand cell communication by revealing a previously unknown, and critical component of the insulin signalling pathway.

Purpose Current data suggests that potentially inappropriate medicines (PIMs) are common in palliative cancer patients; however, there is a lack of criteria to assist clinicians in identifying PIMs in these patients. The aims of this study were to design and validate a deprescribing guideline for palliative cancer patients and to undertake a descriptive analysis of the identified PIMs. Methods This prospective, non-interventional cohort study consisted of four major stages: developing an ‘OncPal Deprescribing Guideline’ from current evidence, the prospective recruitment of consecutive palliative cancer inpatients with an estimated <6-month prognosis, the assessment of all medications to identify PIMs using both a panel of medical experts without access to the guideline as well as a Clinical Pharmacist independently using the OncPal Deprescribing Guideline and the evaluation of the guideline by testing concordance. Descriptive data on the incidence of PIMs identified were also assessed. Results A total of 61 patients were recruited. The OncPal Deprescribing Guideline matched 94 % of 617 medicines to the expert panel with a Kappa value of 0.83 [95 % CI (0.76, 0.89)] demonstrating an ‘outstanding’ concordance. Forty-three (70 %) patients were taking at least one PIM, with 21.4 % of the total medicines assessed identified as PIMs. The medication-associated cost per patient/month was AUD$26.71. Conclusion A guideline to assist in the de-escalation of inappropriate medications in palliative cancer patients was developed from current literature. The OncPal Deprescribing Guideline was successfully validated, demonstrating statistically significant concordance with an expert panel. We found that the incidence of PIMs was high in our patient group, demonstrating the potential benefits for the OncPal Deprescribing Guideline in clinical practice.

Variants in the LIM homeobox transcription factor 1-beta (LMX1B) gene predispose individuals to elevated intraocular pressure (IOP), a key risk factor for glaucoma. However, the effect of LMX1B mutations varies widely between individuals. To better understand the mechanisms underlying LMX1B-related phenotypes and individual differences, we backcrossed the Lmx1bV265D (also known as Lmx1bIcst) allele onto the C57BL/6J (B6), 129/Sj (129), C3A/BLiA-Pde6b+/J (C3H) and DBA/2J-Gpnmb+ (D2-G) mouse strain backgrounds. Strain background had a significant effect on the onset and severity of ocular phenotypes in Lmx1bV265D/+ mutant mice. Mice of the B6 background were the most susceptible to developing abnormal IOP distribution, severe anterior segment developmental anomalies (including malformed eccentric pupils, iridocorneal strands and corneal abnormalities) and glaucomatous nerve damage. By contrast, Lmx1bV265D mice of the 129 background were the most resistant to developing anterior segment abnormalities, had less severe IOP elevation than B6 mutants at young ages and showed no detectable nerve damage. To identify genetic modifiers of susceptibility to Lmx1bV265D-induced glaucoma-associated phenotypes, we performed a mapping cross between mice of the B6 (susceptible) and 129 (resistant) backgrounds. We identified a modifier locus on Chromosome 18, with the 129 allele(s) substantially lessening severity of ocular phenotypes, as confirmed by congenic analysis. By demonstrating a clear effect of genetic background in modulating Lmx1b-induced phenotypes, providing a panel of strains with different phenotypic severities and identifying a modifier locus, this study lays a foundation for better understanding the roles of LMX1B in glaucoma with the goal of developing new treatments.

Simon John and Mounira Hmani-Aifa and colleagues show that mutation of the serine protease gene Prss56 causes elevated intraocular pressure and angle closure glaucoma in mice. They also identified PRSS56 mutations that cause posterior microphthalmia in humans. Angle-closure glaucoma (ACG) is a subset of glaucoma affecting 16 million people 1 , 2 , 3 . Although 4 million people are bilaterally blind from ACG 4 , 5 , the causative molecular mechanisms of ACG remain to be defined. High intraocular pressure induces glaucoma in ACG. High intraocular pressure traditionally was suggested to result from the iris blocking or closing the angle of the eye, thereby limiting aqueous humor drainage. Eyes from individuals with ACG often have a modestly decreased axial length, shallow anterior chamber and relatively large lens, features that predispose to angle closure 6 . Here we show that genetic alteration of a previously unidentified serine protease (PRSS56) alters axial length and causes a mouse phenotype resembling ACG. Mutations affecting this protease also cause a severe decrease of axial length in individuals with posterior microphthalmia. Together, these data suggest that alterations of this serine protease may contribute to a spectrum of human ocular conditions including reduced ocular size and ACG.

Mutations in the LIM-homeodomain transcription factor LMX1B cause nail-patella syndrome, an autosomal dominant pleiotrophic human disorder in which nail, patella and elbow dysplasia is associated with other skeletal abnormalities and variably nephropathy and glaucoma. It is thought to be a haploinsufficient disorder. Studies in the mouse have shown that during development Lmxlb controls limb dorsal-ventral patterning and is also required for kidney and eye development, midbrain-hindbrain boundary establishment and the specification of specific neuronal subtypes. Mice completely deficient for Lmxlb die at birth. In contrast to the situation in humans, heterozygous null mice do not have a mutant phenotype. Here we report a novel mouse mutant Icst, an N-ethyl-N-nitrosourea-induced missense substitution, V265D, in the homeodomain of LMX1B that abolishes DNA binding and thereby the ability to transactivate other genes. Although the homozygous phenotypic consequences of Icst and the null allele of Lmxlb are the same, heterozygous Icst elicits a phenotype whilst the null allele does not. Heterozygous Icst causes glaucomatous eye defects and is semi-lethal, probably due to kidney failure. We show that the null phenotype is rescued more effectively by an Lmxlb transgene than is Icst. Co-immunoprecipitation experiments show that both wild-type and Icst LMX1B are found in complexes with LIM domain binding protein 1 (LDB1), resulting in lower levels of functional LMX1B in Icst heterozygotes than null heterozygotes. We conclude that Icst is a dominant-negative allele of Lmxlb. These findings indicate a reassessment of whether nail-patella syndrome is always haploinsufficient. Furthermore, Icst is a rare example of a model of human glaucoma caused by mutation of the same gene in humans and mice.

Objectives Cancer patients who have transitioned from curative intent chemotherapy or radiotherapy to palliative therapy have limited life expectancies. Due to this, medications for primary and secondary prevention or those with no short-term benefit are potentially inappropriate medicines in this patient group. These medications often have potentially harmful profiles, increasing the patient’s adverse drug events, pill burden, and medication costs. This review evaluates the most current evidence to assess the outcomes and potential methods used for identifying and ceasing potentially inappropriate medications (PIMs) in palliative cancer patients. Methods A systematic review of the literature was conducted using the databases Ovid MEDLINE, PubMed, EMBASE, IPA, and CINAHL. Results Of the 51 articles examined in detail, three studies relating to cancer have been evaluated. In these retrospective and cross-sectional studies, the incidence of PIMs was shown in approximately 20 % of patients, although the studies were inconsistent. In addition, six studies were identified that demonstrated the evidence in other population groups; these studies have been selected to establish the evidence in large-scale retrospective studies, prospective cross-sectional studies, both demonstrating the prevalence of PIMs, as well as the outcomes of ceasing PIMs. Conclusion There is evidence that PIMs are commonly prescribed in palliative care patients. There are no studies that have identified the impact of ceasing PIMS in this setting. Published tools and implemented strategies have focused on the elderly populations. Further research is warranted in establishing clear guidelines for the identification of PIMs in palliative cancer patients as well as interventional studies assessing the outcomes of ceasing PIMs in these patients.

Persistent hiccups are a frustrating experience for palliative care patients, and can have a profound impact on their quality of life. This article provides an evidence-based approach overview of the causes and treatment of this not infrequently debilitating condition for such patients, with a management algorithm. In situations where no readily reversible cause is identified, or where simple physical manoeuvres, such as breath holding have failed, a systematic approach is required. Hiccups can be broadly divided into central and peripheral types. These respond differently to pharmacological intervention. The drug of choice for central causes of persistent hiccups is baclofen, with metoclopramide recommended as the first choice for peripheral causes. Midazolam may be useful in cases of terminal illness. Interventional procedures such as vagal or phrenic nerve block or stimulation should be considered in patients who are refractory to medications. The management of persistent hiccups still presents an ongoing clinical challenge however, requiring further research on pathophysiology and treatment strategies. Multinational randomised controlled trials to evaluate and compare both current and new medications or procedures to better manage this difficult condition are suggested as a means of reaching this goal.