Role of adipocyte-derived lipoprotein lipase in adipocyte hypertrophy

<p>Abstract</p> <p>Background</p> <p>A major portion of available fatty acids for adipocyte uptake is derived from lipoprotein lipase (LPL)-mediated hydrolysis of circulating lipoprotein particles. In vivo studies aimed at identifying the precise role of adipocyte-derived LPL in fat storage function of adipose tissue have been unable to provide conclusive evidence due to compensatory mechanisms that activate endogenous fatty acid synthesis. To address this gap in knowledge, we have measured the effect of reducing adipocyte LPL expression on intracellular lipid accumulation using a well-established cultured model of adipocyte differentiation.</p> <p>Methods</p> <p>siRNA specific for mouse LPL was transfected into 3T3-L1 adipocytes. Expression of LPL was measured by quantitative real-time PCR and cell surface-associated LPL enzymatic activity was measured by colorimetric detection following substrate (p-nitrophenyl butyrate) hydrolysis. Apolipoprotein CII and CIII expression ratios were also measured by qRT-PCR. Intracellular lipid accumulation was quantified by Nile Red staining.</p> <p>Results</p> <p>During differentiation of 3T3-L1 pre-adipocytes, LPL mRNA expression increases 6-fold resulting in a 2-fold increase in cell surface-associated LPL enzymatic activity. Parallel to this increase in LPL expression, we found that intracellular lipids increased ~10-fold demonstrating a direct correlation between adipocyte-derived LPL expression and lipid storage. We next reduced LPL expression in adipocytes using siRNA transfections to directly quantify the contributions of adipocyte-derived LPL to lipid storage, This treatment reduced LPL mRNA expression and cell surface-associated LPL enzymatic activity to ~50% of non-treated controls while intracellular lipid levels were reduced by 80%. Exogenous addition of purified LPL (to restore extracellular lipolytic activity) or palmitate (as a source of free fatty acids) to siRNA-treated cells restored intracellular lipid levels to those measured for non-treated controls. We also found that adipocytes express apolipoprotein CII and CIII and, in addition, the apoCII/apoCIII ratio remains largely unchanged in cells with reduced LPL expression.</p> <p>Conclusion</p> <p>We provide evidence that adipocyte-derived LPL is required for efficient fatty acid uptake and storage, and that adipocytes express their own source of apoCII and apoCIII for regulating extracellular LPL activity. These findings demonstrate that adipocytes are capable of producing the necessary enzymatic components and co-factors for efficient lipid storage independent of vascular sources.</p

Syndecan-1 mediates internalization of apoE-VLDL through a low density lipoprotein receptor-related protein (LRP)-independent, non-clathrin-mediated pathway

BACKGROUND: Triacylglyerol-rich very low density lipoprotein (VLDL) particles are the primary carriers of fatty acids in the circulation and as such serve as a rich energy source for peripheral tissues. Receptor-mediated uptake of these particles is dependent upon prior association with apolipoprotein E (apoE-VLDL) and is brought about by cell surface heparan sulfate proteoglycans (HSPG) in some cell types and by the low density lipoprotein receptor-related protein (LRP) in others. Although LRP's role in apoE-VLDL uptake has been well studied, the identity of the HSPG family member that mediates apoE-VLDL uptake has not been established. We investigated if syndecan-1 (Syn-1), a transmembrane cell surface HSPG, is able to mediate the internalization of apoE-VLDL and examined the relationship between Syn-1 and LRP toward apoE-VLDL uptake. For this study, we used a human fibroblast cell line (GM00701) that expresses large amounts of LRP, but possesses no LDL receptor activity to eliminate its contributions toward apoE-VLDL uptake. RESULTS: Although LRP in these cells is fully active as established by substantial α(2)macroglobulin binding and internalization, uptake of apoE-VLDL is absent. Expression of human Syn-1 cDNA restored apoE-VLDL binding and uptake by these cells. Competition for this uptake with an LRP ligand-binding antagonist had little or no effect, whereas co-incubation with heparin abolished apoE-VLDL internalization. Depleting Syn-1 expressing cells of K(+), to block clathrin-mediated endocytosis, showed no inhibition of Syn-1 internalization of apoE-VLDL. By contrast, treatment of cells with nystatin to inhibit lipid raft function, prevented the uptake of apoE-VLDL by Syn-1. CONCLUSION: These data demonstrate that Syn-1 is able to mediate apoE-VLDL uptake in human fibroblasts with little or no contribution from LRP and that the endocytic path taken by Syn-1 is clathrin-independent and relies upon lipid raft function. These data are consistent with previous studies demonstrating Syn-1 association with lipid raft domains

Ecoturismo marino en el golfo de California y península de Baja California: tendencias de investigación y vacíos de información

Achieving equitable and sustainable ecotourism requires a wide range of multidisciplinary and cross-scale information, particularly given the growing scale of ecotourism operations and continuing governance and climate challenges. Ecosystems in Mexico’s Gulf of California and Baja California Peninsula support a thriving ecotourism industry that has quickly expanded over the last few decades, potentially outpacing research into current performance and future sustainable development opportunities. We develop and apply a formal literature review approach to characterize academic marine ecotourism literature, highlight key insights and identify research strengths and gaps, and thus analyse almost 50 publications for the region from 1994 to 2014. There has been a significant increase in the number of various types of publications; most (68%) focus on ecological themes, 25% on economics, and 7% on social aspects of human wellbeing. There are also trends towards research on specific species (e.g. mammals, fish and sharks) and in specific areas. A common theme in publication conclusions is the need for collaboration from all stakeholder groups. We discuss these findings, and address potential limitations of our method, with a view to informing sound policies to ensure that ecotourism can provide equitable benefits to local communities while incentivizing sustainable practices and nature conservation.El desarrollo equitativo y sostenible del ecoturismo debe considerar una amplia gama de información multidisciplinaria y a varias escalas, particularmente dada la creciente magnitud de las operaciones de ecoturismo y los retos de gobernanza y climáticos. Los ecosistemas en el golfo de California y península de Baja California en México mantienen a una próspera industria de ecoturismo que se ha expandido rápidamente a lo largo de las últimas décadas, posiblemente dejando atrás a la investigación respecto a sus operaciones actuales y las oportunidades para el desarrollo sostenible a futuro. Desarrollamos y aplicamos una revisión formal de literatura para caracterizar a las publicaciones académicas respecto al ecoturismo, señalar tendencias clave e identificar fortalezas y vacíos de investigación, analizando casi 50 publicaciones para la región desde 1994 al 2014. Ha habido un incremento significativo en la cantidad de publicaciones de varios tipos; la mayoría (68%) se enfocan en temas ecológicos, 25% en economía y 7% en aspectos sociales del bienestar humano. También existe una tendencia hacia investigación de ciertas especies (e.g. mamíferos, peces, tiburones) y en regiones específicas. Un tema común en las conclusiones de las publicaciones analizadas es la necesidad de colaboración por todos los grupos de actores. Discutimos estos resultados, y las posibles limitaciones de nuestro método, en el contexto de informar políticas adecuadas para asegurar que el ecoturismo pueda proveer beneficios equitativos a comunidades locales al mismo tiempo que se incentivan las prácticas sostenibles y la conservación de la naturaleza

The ideal healthcare: priorities of people with chronic conditions and their carers

Background It is well established that health consumer opinions should be considered in the design, delivery, and evaluation of health services. However, the opinions of people with chronic conditions and their carers and what they actually consider as ideal healthcare is limited. The aim of this study is to investigate the healthcare priorities of consumers with chronic conditions and their carers, if there are differences between these two groups, and if priorities differ depending on geographical location. Methods The nominal group technique was used as a method to identify what is currently important to, or valued by, participants. This method was also particularly suited to learning about healthcare problems and generating important solutions, thereby helping to bridge the gap between research and policy. Recruitment was carried out via purposive sampling, with the assistance of community pharmacies, general practices, various health agencies, government and non-government organisations. A total of 11 nominal groups were conducted; five groups consisted predominantly of consumers (n = 33 participants), two groups consisted predominantly of carers (n = 12 participants) and four were mixed groups, i.e. consumers, carers, and both (n = 26 participants). Results The findings suggested that to create a model of ideal healthcare for people with chronic conditions and their carers, appropriate and timely healthcare access was of paramount importance. Continuity and coordinated care, patient-centred care and affordability were equally the second most important healthcare priorities for all groups. When compared with other groups, access was discussed more frequently among participants residing in the rural area of Mount Isa. Compared to consumers, carers also discussed priorities that were more reminiscent with their caring roles, such as increased access and continuity and coordinated care. Conclusions Access to healthcare is the most important priority for people with chronic conditions and their carers. In the event of inappropriate access for certain groups, all other efforts to increase the quality of healthcare delivery, e.g. patient-centred care, may be pointless. However, health professionals alone may be limited in their ability to address the concerns related to healthcare access; structural changes by health policy makers may be needed

Kinetic study and thermodynamic equilibrium modeling of the Co(II) and Mn(II) bioadsorption using the Rhodococcus opacus strain

Microbial biomass is considered a renewable and environmentally friendly resource. Thus, the research conducted a kinetic study and thermodynamic equilibrium modeling of the cobalt (Co) and manganese (Mn) bioadsorption process using the Rhodococcus opacus (RO) strain as a biosorbent. The inactive biomass subjected to 0.1 M NaOH pretreatment was brought into contact with synthetic solutions of Co and Mn. The experimental data for the Co(II) and Mn(II) bioadsorption process were fit to the Langmuir model with kads of 0.65 and 0.11 L.mg-1, respectively. A better statistical fit was also obtained for the pseudo-second order kinetic model (R2Co(II) = 0.994 and R2Mn(II) = 0.995), with 72.3% Co(II) and 80% Mn(II) removals during the first 10 min. In addition, a higher affinity of RO for the Co(II) ion was observed, with maximum uptake values of 13.42 mg.g-1; however, a higher adsorption rate was observed for Mn(II) ion (k = 0.21 g.mg-1.min-1 at 318 K). The bioadsorption process was spontaneous and dependent on temperature, being endothermic and irreversible for the Co(II) ion (∆H = 2951.91 J.mol-1) and exothermic and reversible for the Mn(II) ion (∆H = -2974.8 J.mol-1). The kinetic and thermodynamic equilibrium modeling allowed to identify the main mechanisms involved in the biosorption process of both metals.Campus San Juan de Luriganch

A Chemical Analog of Curcumin as an Improved Inhibitor of Amyloid Abeta Oligomerization

Amyloid-like plaques are characteristic lesions defining the neuropathology of Alzheimer's disease (AD). The size and density of these plaques are closely associated with cognitive decline. To combat this disease, the few therapies that are available rely on drugs that increase neurotransmission; however, this approach has had limited success as it has simply slowed an imminent decline and failed to target the root cause of AD. Amyloid-like deposits result from aggregation of the Aβ peptide, and thus, reducing amyloid burden by preventing Aβ aggregation represents an attractive approach to improve the therapeutic arsenal for AD. Recent studies have shown that the natural product curcumin is capable of crossing the blood-brain barrier in the CNS in sufficient quantities so as to reduce amyloid plaque burden. Based upon this bioactivity, we hypothesized that curcumin presents molecular features that make it an excellent lead compound for the development of more effective inhibitors of Aβ aggregation. To explore this hypothesis, we screened a library of curcumin analogs and identified structural features that contribute to the anti-oligomerization activity of curcumin and its analogs. First, at least one enone group in the spacer between aryl rings is necessary for measureable anti-Aβ aggregation activity. Second, an unsaturated carbon spacer between aryl rings is essential for inhibitory activity, as none of the saturated carbon spacers showed any margin of improvement over that of native curcumin. Third, methoxyl and hydroxyl substitutions in the meta- and para-positions on the aryl rings appear necessary for some measure of improved inhibitory activity. The best lead inhibitors have either their meta- and para-substituted methoxyl and hydroxyl groups reversed from that of curcumin or methoxyl or hydroxyl groups placed in both positions. The simple substitution of the para-hydroxy group on curcumin with a methoxy substitution improved inhibitor function by 6-7-fold over that measured for curcumin

Curcumin and resveratrol inhibit nuclear factor-kappaB-mediated cytokine expression in adipocytes

<p>Abstract</p> <p>Background</p> <p>Adipocytes express inflammatory mediators that contribute to the low-level, chronic inflammation found in obese subjects and have been linked to the onset of cardiovascular disorders and insulin resistance associated with type 2 diabetes mellitus. A reduction in inflammatory gene expression in adipocytes would be expected to reverse this low-level, inflammatory state and improve cardiovascular function and insulin sensitivity. The natural products, curcumin and resveratrol, are established anti-inflammatory compounds that mediate their effects by inhibiting activation of NF-κB signaling. In the present study, we examined if these natural products can inhibit NF-κB activation in adipocytes and in doing so reduce cytokine expression.</p> <p>Methods</p> <p>Cytokine (TNF-α, IL-1β, IL-6) and COX-2 gene expression in 3T3-L1-derived adipocytes was measured by quantitative real-time PCR (qRT-PCR) with or without TNFα-stimulation. Cytokine protein and prostaglandin E₂(PGE₂) expression were measured by ELISA. Effects of curcumin and resveratrol were evaluated by treating TNFα-stimulated adipocytes with each compound and 1) assessing the activation state of the NF-κB signaling pathway and 2) measuring inflammatory gene expression by qRT-PCR and ELISA.</p> <p>Results</p> <p>Both preadipocytes and differentiated adipocytes express the genes for TNF-α, IL-6, and COX-2, key mediators of the inflammatory response. Preadipocytes were also found to express IL-1β; however, IL-1β expression was absent in differentiated adipocytes. TNF-α treatment activated NF-κB signaling in differentiated adipocytes by inducing IκB degradation and NF-κB translocation to the nucleus, and as a result increased IL-6 (6-fold) and COX-2 (2.5-fold) mRNA levels. TNF-α also activated IL-1β gene expression in differentiated adipocytes, but had no effect on endogenous TNF-α mRNA levels. No detectable TNFα or IL-1β was secreted by adipocytes. Curcumin and resveratrol treatment inhibited NF-κB activation and resulted in a reduction of TNF-α, IL-1β, IL-6, and COX-2 gene expression (IC₅₀= 2 μM) and a reduction of secreted IL-6 and PGE₂(IC₅₀~ 20 μM).</p> <p>Conclusion</p> <p>Curcumin and resveratrol are able to inhibit TNFα-activated NF-κB signaling in adipocytes and as a result significantly reduce cytokine expression. These data suggest that curcumin and resveratrol may provide a novel and safe approach to reduce or inhibit the chronic inflammatory properties of adipose tissue.</p

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead