This Is the End: Regulation of Rab7 Nucleotide Binding in Endolysosomal Trafficking and Autophagy

Rab7 – or in yeast, Ypt7p – governs membrane trafficking in the late endocytic and autophagic pathways. Rab7 also regulates mitochondrion-lysosome contacts, the sites of mitochondrial fission. Like all Rab GTPases, Rab7 cycles between an “active” GTP-bound form that binds downstream effectors – e.g., the HOPS and retromer complexes and the dynactin-binding Rab-interacting lysosomal protein (RILP) – and an “inactive” GDP-bound form that cannot bind effectors. Accessory proteins regulate the nucleotide binding state of Rab7: guanine nucleotide exchange factors (GEFs) stimulate exchange of bound GDP for GTP, resulting in Rab7 activation, whereas GTPase activating proteins (GAPs) boost Rab7’s GTP hydrolysis activity, thereby inactivating Rab7. This review will discuss the GEF and GAPs that control Rab7 nucleotide binding, and thus regulate Rab7’s activity in endolysosomal trafficking and autophagy. It will also consider how bacterial pathogens manipulate Rab7 nucleotide binding to support intracellular invasion and immune evasion

Minimal Membrane Docking Requirements Revealed by Reconstitution of Rab GTPase-Dependent Membrane Fusion from Purified Components

Rab GTPases and their effectors mediate docking, the initial contact of intracellular membranes preceding bilayer fusion. However, it has been unclear whether Rab proteins and effectors are sufficient for intermembrane interactions. We have recently reported reconstituted membrane fusion that requires yeast vacuolar SNAREs, lipids, and the homotypic fusion and vacuole protein sorting (HOPS)/class C Vps complex, an effector and guanine nucleotide exchange factor for the yeast vacuolar Rab GTPase Ypt7p. We now report reconstitution of lysis-free membrane fusion that requires purified GTP-bound Ypt7p, HOPS complex, vacuolar SNAREs, ATP hydrolysis, and the SNARE disassembly catalysts Sec17p and Sec18p. We use this reconstituted system to show that SNAREs and Sec17p/Sec18p, and Ypt7p and the HOPS complex, are required for stable intermembrane interactions and that the three vacuolar Q-SNAREs are sufficient for these interactions

Correction: Membranes Linked by Trans-Snare Complexes Require Lipids Prone to Non-Bilayer Structure for Progression to Fusion

Like other intracellular fusion events, the homotypic fusion of yeast vacuoles requires a Rab GTPase, a large Rab effector complex, SNARE proteins which can form a 4-helical bundle, and the SNARE disassembly chaperones Sec17p and Sec18p. In addition to these proteins, specific vacuole lipids are required for efficient fusion in vivo and with the purified organelle. Reconstitution of vacuole fusion with all purified components reveals that high SNARE levels can mask the requirement for a complex mixture of vacuole lipids. At lower, more physiological SNARE levels, neutral lipids with small headgroups that tend to form non-bilayer structures (phosphatidylethanolamine, diacylglycerol, and ergosterol) are essential. Membranes without these three lipids can dock and complete trans -SNARE pairing but cannot rearrange their lipids for fusion

Sequential Analysis of Trans-SNARE Formation in Intracellular Membrane Fusion

SM proteins stabilize cis-SNARE complexes leading to a specific preferred topology for trans-SNARE formation

Phosphorylation Provides a Negative Mode of Regulation for the Yeast Rab GTPase Sec4p

The Rab family of Ras-related GTPases are part of a complex signaling circuitry in eukaryotic cells, yet we understand little about the mechanisms that underlie Rab protein participation in such signal transduction networks, or how these networks are integrated at the physiological level. Reversible protein phosphorylation is widely used by cells as a signaling mechanism. Several phospho-Rabs have been identified, however the functional consequences of the modification appear to be diverse and need to be evaluated on an individual basis. In this study we demonstrate a role for phosphorylation as a negative regulatory event for the action of the yeast Rab GTPase Sec4p in regulating polarized growth. Our data suggest that the phosphorylation of the Rab Sec4p prevents interactions with its effector, the exocyst component Sec15p, and that the inhibition may be relieved by a PP2A phosphatase complex containing the regulatory subunit Cdc55p

2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS guideline for the diagnosis and management of patients with stable ischemic heart disease

The recommendations listed in this document are, whenever possible, evidence based. An extensive evidence review was conducted as the document was compiled through December 2008. Repeated literature searches were performed by the guideline development staff and writing committee members as new issues were considered. New clinical trials published in peer-reviewed journals and articles through December 2011 were also reviewed and incorporated when relevant. Furthermore, because of the extended development time period for this guideline, peer review comments indicated that the sections focused on imaging technologies required additional updating, which occurred during 2011. Therefore, the evidence review for the imaging sections includes published literature through December 2011

Empower Veterans Program (EVP): a chronic pain management program demonstrates positive outcomes among veterans

Abstract Background Chronic pain is a highly prevalent health condition among veterans. Traditional pharmacological interventions present unique challenges for chronic pain management including prescription opioid addiction and overdose. In alignment with the 2016 Comprehensive Addiction and Recovery Act and VA’s Stepped Care Model to meet veterans’ pain management needs, the Offices of Rural Health and Pain Management, Opioid Safety, and Prescription Drug Monitoring Program (PMOP) funded an enterprise-wide initiative to implement a Step 3 integrated tele-pain program: Empower Veterans Program (EVP). EVP provides veterans with chronic pain self-care skills using a whole health driven approach to pain management. Objectives The Comprehensive Addiction and Recovery Act prompted the strategic approach to offer non-pharmacological options to meet veterans’ pain management needs. EVP, a 10-week interdisciplinary group medical appointment, leverages Acceptance and Commitment Therapy, Mindful Movement, and Whole Health to provide veterans with chronic pain self-care skills. This evaluation was conducted to describe participant characteristics, graduation, and satisfaction rates; and assess pre-post patient-reported outcomes (PRO) associated with EVP participation. Methods A sample of 639 veterans enrolled in EVP between May, 2015 and December, 2017 provided data to conduct descriptive analyses to assess participant demographics, graduation, and satisfaction rates. PRO data were analyzed using a within-participants pre-post design, and linear mixed-effects models were used to examine pre-post changes in PRO. Results Of 639 participants, 444 (69.48%) graduated EVP. Participant median program satisfaction rating was 8.41 (Interquartile Range: 8.20–9.20). Results indicate pre-post EVP improvements (Bonferroni-adjusted p < .003) in the three primary pain outcomes (intensity, interference, catastrophizing), and 12 of 17 secondary outcomes, including physical, psychological, health-related quality of life (HRQoL), acceptance, and mindfulness measures. Discussion Data suggest that EVP has significant positive outcomes in pain, psychological, physical, HRQoL, acceptance, and mindfulness measures for veterans with chronic pain through non-pharmacological means. Future evaluations of intervention dosing effect and long-term effectiveness of the program is needed