Histodenz Separation of Lysosomal Subpopulations for Analysis of Chaperone-mediated Autophagy.

Chaperone-mediated autophagy (CMA) is the most selective form of lysosomal proteolysis, in which proteins are individually selected for lysosomal degradation. CMA degradation targets bear a pentapeptide consensus motif that is recognized by the cytosolic chaperone HSPA8 (Hsc70), which participates in the trafficking of the target to the lysosomal surface. From there, it is translocated into the lysosomal lumen, independent of vesicle fusion, in a process dependent upon the lysosomal transmembrane protein LAMP2A. There are limited tools for studying CMA in whole cells and tissues, and many of the best techniques for studying CMA rely on the preparation of lysosome enriched fractions. Such experiments include (1) the in vitro evaluation of CMA substrate uptake activity, (2) the characterization of changes to lysosomal resident and CMA regulatory proteins, and (3) lysosomal targetomics, i.e., the use of quantitative proteomics to characterize lysosomal degradation targets. Previous studies using discontinuous metrizamide gradients have shown that a subpopulation of liver lysosomes is responsible for the majority of CMA activity ("CMA+ "). These CMA+ lysosomes are low density and have higher levels of MTORC2 relative to the "CMA- " lysosomes, which are high density and have higher levels of MTORC1. Because of safety concerns surrounding metrizamide, however, this compound is difficult to obtain, and it is impractically expensive. Here, we have provided protocols for isolation of lysosomal subpopulations for CMA-related analyses from mouse liver using Histodenz, a safe and affordable alternative to metrizamide. Supplementary protocols show how to perform CMA activity assays with appropriate statistical analysis, and how to analyze for lysosomal breakage/membrane integrity. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol: Isolation of lysosomal subpopulations from mouse liver using discontinuous Histodenz gradients Alternate Protocol: Isolation of lysosomes from cultured cells using discontinuous Histodenz gradients Support Protocol 1: Verifying enrichment of lysosomal markers in lysosome-enriched fractions Support Protocol 2: Measuring in vitro uptake of CMA substrates Support Protocol 3: Measuring lysosomal membrane integrity by hexosaminidase assay.

Recapitulation of anti-aging phenotypes by global overexpression of PTEN in mice.

The PTEN gene negatively regulates the oncogenic PI3K-AKT pathway by encoding a lipid and protein phosphatase that dephosphorylates lipid phosphatidylinositol-3,4,5-triphosphate (PIP3) resulting in the inhibition of PI3K and downstream inhibition of AKT. Overexpression of PTEN in mice leads to a longer lifespan compared to control littermates, although the mechanism is unknown. Here, we provide evidence that young adult PTENOE mice exhibit many characteristics shared by other slow-aging mouse models, including those with mutations that affect GH/IGF1 pathways, calorie-restricted mice, and mice treated with anti-aging drugs. PTENOE white adipose tissue (WAT) has increased UCP1, a protein linked to increased thermogenesis. WAT of PTENOE mice also shows a change in polarization of fat-associated macrophages, with elevated levels of arginase 1 (Arg1, characteristic of M2 macrophages) and decreased production of inducible nitric oxide synthase (iNOS, characteristic of M1 macrophages). Muscle and hippocampus showed increased expression of the myokine FNDC5, and higher levels of its cleavage product irisin in plasma, which has been linked to increased conversion of WAT to more thermogenic beige/brown adipose tissue. PTENOE mice also have an increase, in plasma and liver, of GPLD1, which is known to improve cognition in mice. Hippocampus of the PTENOE mice has elevation of both BDNF and DCX, indices of brain resilience and neurogenesis. These changes in fat, macrophages, liver, muscle, hippocampus, and plasma may be considered "aging rate indicators" in that they seem to be consistently changed across many of the long-lived mouse models and may help to extend lifespan by delaying many forms of late-life illness. Our new findings show that PTENOE mice can be added to the group of long-lived mice that share this multi-tissue suite of biochemical characteristics.

PTEN is both an activator and a substrate of chaperone-mediated autophagy.

PTEN is a crucial negative regulator of the INS/PI3K/AKT pathway and is one of the most commonly mutated tumor suppressors in cancer. Global overexpression (OE) of PTEN in mice shifts metabolism to favor oxidative phosphorylation over glycolysis, reduces fat mass, and extends the lifespan of both sexes. We demonstrate that PTEN regulates chaperone-mediated autophagy (CMA). Using cultured cells and mouse models, we show that PTEN OE enhances CMA, dependent upon PTEN's lipid phosphatase activity and AKT inactivation. Reciprocally, PTEN knockdown reduces CMA, which can be rescued by inhibiting class I PI3K or AKT. Both PTEN and CMA are negative regulators of glycolysis and lipid droplet formation. We show that suppression of glycolysis and lipid droplet formation downstream of PTEN OE depends on CMA activity. Finally, we show that PTEN protein levels are sensitive to CMA and that PTEN accumulates in lysosomes with elevated CMA. Collectively, these data suggest that CMA is both an effector and a regulator of PTEN.

LAMP2A, and other chaperone-mediated autophagy related proteins, do not decline with age in genetically heterogeneous UM-HET3 mice.

Chaperone-mediated autophagy (CMA) selectively degrades proteins that are crucial for glycolysis, fatty acid metabolism, and the progression of several age-associated diseases. Several previous studies, each of which evaluated males of a single inbred mouse or rat strain, have reported that CMA declines with age in many tissues, attributed to an age-related loss of LAMP2A, the primary and indispensable component of the CMA translocation complex. This has led to a paradigm in the field of CMA research, stating that the age-associated decline in LAMP2A in turn decreases CMA, contributing to the pathogenesis of late-life disease. We assessed LAMP2A levels and CMA substrate uptake in both sexes of the genetically heterogeneous UM-HET3 mouse stock, which is the current global standard for the evaluation of anti-aging interventions. We found no evidence for age-related changes in LAMP2A levels, CMA substrate uptake, or whole liver levels of CMA degradation targets, despite identifying sex differences in CMA.

A systematic scoping review on the evidence behind debriefing practices for the wellbeing/emotional outcomes of healthcare workers.

Introduction: Debriefings give healthcare workers voice through the opportunity to discuss unanticipated or difficult events and recommend changes. The typical goal of routine debriefings has been to improve clinical outcomes by learning through discussion and reflection of events and then transferring that learning into clinical practice. However, little research has investigated the effects of debriefings on the emotional experiences and well-being of healthcare workers. There is some evidence that debriefings are a multi-faceted and cost-effective intervention for minimising negative health outcomes, but their use is inconsistent and they are infrequently adopted with the specific intention of giving healthcare workers a voice. The purpose of this systematic scoping review is therefore to assess the scope of existing evidence on debriefing practices for the well-being and emotional outcomes of healthcare workers. Methods: Following screening, 184 papers were synthesised through keyword mapping and exploratory trend identification. Results: The body of evidence reviewed were clustered geographically, but diverse on many other criteria of interest including the types of evidence produced, debriefing models and practices, and outcomes captured. Discussion: The current review provides a clear map of our existing understanding and highlights the need for more systematic, collaborative and rigorous bodies of evidence to determine the potential of debriefing to support the emotional outcomes of those working within healthcare. Systematic Review Registration: https://osf.io/za6rj.

A last resort? A scoping review of patient and healthcare worker attitudes toward strike action.

While strike action has been common since the industrial revolution, it often invokes a passionate and polarising response, from the strikers themselves, from employers, governments and the general public. Support or lack thereof from health workers and the general public is an important consideration in the justification of strike action. This systematic review sought to examine the impact of strike action on patient and clinician attitudes, specifically to explore (1) patient and health worker support for strike action and (2) the predictors for supporting strike action and the reasons given for engaging in strike action. A systematic scoping review was employed to identify all relevant literature, followed by a textual narrative synthesis. A total of 34 studies met inclusion criteria. Support for strike action was largely context-dependent. A range of factors impact support for strike action; broader cultural and structural factors, such as unionisation and general acceptance of strike action; systemic factors, such as the nature of the healthcare system, including infrastructure and work conditions; the strike itself and a range of individual factors, the most notable of which was being a student or in an early career stage. There were also some surprising results, for example, during doctors strike, nurses were provided with the opportunity to expand their role, which led to greater professional autonomy and job satisfaction.

Trust and risk communication in high-risk organizations: a test of principles from social risk research.

This study explored the effects of open communication about occupational risks on workers' trust beliefs and trust intentions toward risk management, and the resilience of these beliefs and intentions to further risk information. An experimental survey of 393 student nurses showed the importance of open communication in the development of worker trust in risk management. Consistent with the trust asymmetry principle, we found that the increase in trust beliefs following open communication was weaker than the reduction in trust following a lack of communication. Further, the level of trust developed through communication (or lack of) influenced the way that subsequent risk information was processed. Negative risk information reduced trust beliefs in nurses with already low levels of trust while positive risk information increased trust beliefs only in those with already high levels. A similar pattern of results emerged for nurses' trust intentions, although the magnitude of these effects was weaker. The implications of these findings for occupational risk management are discussed.

Explicit and implicit trust within safety culture.

Safety culture is an important topic for managers in high-hazard industries because a deficient safety culture has been linked to organizational accidents. Many researchers have argued that trust plays a central role in models of safety culture but trust has rarely been measured in safety culture/climate studies. This article used explicit (direct) and implicit (indirect) measures to assess trust at a UK gas plant. Explicit measures assessed trust by asking workers to consider and state their attitude to attitude objects. Implicit measures assessed trust in a more subtle way by using a priming task that relies on automatic attitude activation. The results show that workers expressed explicit trust for their workmates, supervisors, and senior managers, but only expressed implicit trust for their workmates. The article proposes a model that conceptualizes explicit trust as part of the surface levels of safety culture and implicit trust as part of the deeper levels of safety culture. An unintended finding was the positive relationship between implicit measures of trust and distrust, which suggests that trust and distrust are separate constructs. The article concludes by considering the implications for safety culture and trust and distrust in high-hazard industries.