The SNARE Protein SNAP23 and the SNARE-Interacting Protein Munc18c in Human Skeletal Muscle Are Implicated in Insulin Resistance/Type 2 Diabetes

OBJECTIVE-Our previous studies suggest that the SNARE protein synaptosomal-associated protein of 23 kDa (SNAP23) is involved in the link between increased lipid levels and insulin resistance in cardiomyocytes. The objective was to determine whether SNAP23 may also be involved in the known association between lipid accumulation in skeletal muscle and insulin resistance/type 2 diabetes in humans, as well as to identify a potential regulator of SNAP23. RESEARCH DESIGN AND METHODS-We analyzed skeletal muscle biopsies from patients with type 2 diabetes and healthy, insulin-sensitive control subjects for expression (mRNA and protein) and intracellular localization (subcellular fractionation and immunohistochemistry) of SNAP23, and for expression of proteins known to interact with SNARE proteins. Insulin resistance was determined by a euglycemic hyperinsulinemic clamp Potential mechanisms for regulation of SNAP23 were also investigated in the skeletal muscle cell line L6. RESULTS-We showed increased SNAP23 levels in skeletal muscle from patients with type 2 diabetes compared with that from lean control subjects Moreover, SNAP23 was redistributed from the plasma membrane to the microsomal/cytosolic compartment in the patients with the type 2 diabetes Expression of the SNARE-interacting protein Munc18c was higher in skeletal muscle from patients with type 2 diabetes Studies in L6 cells showed that Munc18c promoted the expression of SNAP23. CONCLUSIONS-We have translated our previous in vitro results into humans by showing that there is a change in the distribution of SNAP23 to the interior of the cell in skeletal muscle from patients with type 2 diabetes. We also showed that Munc18c is a potential regulator of SNAP23. Diabetes 59: 1870-1878, 201

RESEARCH ARTICLE Open Access

Factors influencing patient safety in Sweden: perceptions of patient safety officers in the county council

Glucosylceramide modifies the LPS-induced inflammatory response in macrophages and the orientation of the LPS/TLR4 complex in silico

Toll-like receptor 4 (TLR4) is activated by bacterial lipopolysaccharide (LPS), which drives the production of proinflammatory cytokines. Earlier studies have indicated that cholesterol-and glycosphingolipid-rich subregions of the plasma membrane (lipid domains) are important for TLR4-mediated signaling. We report that inhibition of glucosylceramide (GluCer) synthase, which resulted in decreased concentrations of the glycosphingolipid GluCer in lipid domains, reduced the LPS-induced inflammatory response in both mouse and human macrophages. Atomistic molecular dynamics simulations of the TLR4 dimer complex (with and without LPS in its MD-2 binding pockets) in membranes (in the presence and absence of GluCer) showed that: (1) LPS induced a tilted orientation of TLR4 and increased dimer integrity; (2) GluCer did not affect the integrity of the LPS/TLR4 dimer but reduced the LPS-induced tilt; and (3) GluCer increased electrostatic interactions between the membrane and the TLR4 extracellular domain, which could potentially modulate the tilt. We also showed that GCS inhibition reduced the interaction between TLR4 and the intracellular adaptor protein Mal. We conclude that the GluCer-induced effects on LPS/TLR4 orientation may influence the signaling capabilities of the LPS/TLR4 complex by affecting its interaction with downstream signaling proteins.Peer reviewe

Factors influencing patient safety in Sweden: perceptions of patient safety officers in the county councils

Abstract Background National, regional and local activities to improve patient safety in Sweden have increased over the last decade. There are high ambitions for improved patient safety in Sweden. This study surveyed health care professionals who held key positions in their county council’s patient safety work to investigate their perceptions of the conditions for this work, factors they believe have been most important in reaching the current level of patient safety and factors they believe would be most important for achieving improved patient safety in the future. Methods The study population consisted of 218 health care professionals holding strategic positions in patient safety work in Swedish county councils. Using a questionnaire, the following topics were analysed in this study: profession/occupation; number of years involved in a designated task on patient safety issues; knowledge/overview of the county council’s patient safety work; ability to influence this work; conditions for this work; and the importance of various factors for current and future levels of patient safety. Results The response rate to the questionnaire was 79%. The conditions that had the highest number of responses in complete agreement were “patients’ involvement is important for patient safety” and “patient safety work has good support from the county council’s management”. Factors that were considered most important for achieving the current level of patient safety were root cause and risk analyses, incident reporting and the Swedish Patient Safety Law. An organizational culture that encourages reporting and avoids blame was considered most important for improved patient safety in the future, closely followed by improved communication between health care practitioners and patients. Conclusion Health care professionals with important positions in the Swedish county councils’ patient safety work believe that conditions for this work are somewhat constrained. They attribute the current levels of patient safety to a broad range of factors and believe that many different solutions can contribute to enhanced patient safety in the future, suggesting that this work must be multifactorial.</p

Factors influencing patient safety in Sweden : perceptions of patient safety officers in the county councils

Background National, regional and local activities to improve patient safety in Sweden have increased over the last decade. There are high ambitions for improved patient safety in Sweden. This study surveyed health care professionals who held key positions in their county council’s patient safety work to investigate their perceptions of the conditions for this work, factors they believe have been most important in reaching the current level of patient safety and factors they believe would be most important for achieving improved patient safety in the future. Methods The study population consisted of 218 health care professionals holding strategic positions in patient safety work in Swedish county councils. Using a questionnaire, the following topics were analysed in this study: profession/occupation; number of years involved in a designated task on patient safety issues; knowledge/overview of the county council’s patient safety work; ability to influence this work; conditions for this work; and the importance of various factors for current and future levels of patient safety. Results The response rate to the questionnaire was 79%. The conditions that had the highest number of responses in complete agreement were “patients’ involvement is important for patient safety” and “patient safety work has good support from the county council’s management”. Factors that were considered most important for achieving the current level of patient safety were root cause and risk analyses, incident reporting and the Swedish Patient Safety Law. An organizational culture that encourages reporting and avoids blame was considered most important for improved patient safety in the future, closely followed by improved communication between health care practitioners and patients. Conclusion Health care professionals with important positions in the Swedish county councils’ patient safety work believe that conditions for this work are somewhat constrained. They attribute the current levels of patient safety to a broad range of factors and believe that many different solutions can contribute to enhanced patient safety in the future, suggesting that this work must be multifactorial.Funding Agencies|Swedish Association of Local Authorities and Regions (SALAR)||</p

ARF6 regulates neuron differentiation through glucosylceramide synthase.

The small GTPase ADP ribosylation factor 6 (ARF6) mediates endocytosis and has in addition been shown to regulate neuron differentiation. Here we investigated whether ARF6 promotes differentiation of Neuro-2a neuronal cells by modifying the cellular lipid composition. We showed that knockdown of ARF6 by siRNA in Neuro-2a cells increased neuronal outgrowth as expected. ARF6 knockdown also resulted in increased glucosylceramide levels and decreased sphingomyelin levels, but did not affect the levels of ceramide or phospholipids. We speculated that the ARF6 knockdown-induced increase in glucosylceramide was caused by an effect on glucosylceramide synthase and, in agreement, showed that ARF6 knockdown increased the mRNA levels and activity of glucosylceramide synthase. Finally, we showed that incubation of Neuro-2a cells with the glucosylceramide synthase inhibitor D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (D-PDMP) normalized the increased neuronal outgrowth induced by ARF6 knockdown. Our results thus show that ARF6 regulates neuronal differentiation through an effect on glucosylceramide synthase and glucosylceramide levels