Shwetha K. Shetty
Apr 1, 2020; 61:546-559
Methods

Sandi M. Azab
Mar 31, 2020; 0:jlr.D120000630v1-jlr.D120000630
Methods

M John Chapman
Apr 15, 2020; 0:jlr.P119000543v1-jlr.P119000543
Patient-Oriented and Epidemiological Research

Henry J. Pownall
May 1, 2020; 61:595-597
Commentary

Eyad Naser
Mar 10, 2020; 0:jlr.RA120000682v1-jlr.RA120000682
Research Articles

Kristen A. Johnson
Apr 23, 2020; 0:jlr.ILR120000836v1-jlr.ILR120000836
Images in Lipid Research

In the second episode of the UK Tech Weekly Podcast host Matt Egan discusses the Mobile World Congress (MWC) with producer Chris Martin before he jets off to Barcelona, including what device launches we are expecting from the likes of LG, Sony and Samsung. Acting editor at Macworld.co.uk David Price chats about the row between Apple and the FBI over encryption (14:50). Finally Scott Carey from Techworld.com discusses challenger banks (25:00) what they are, what the technology looks like and why you should care.  

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In this week's UK Tech Weekly Podcast host Matt Egan is joined by online editor at Techworld.com Scott Carey to discuss all of the news coming out of Microsoft's Build 2016 developer conference, before being joined by producer Chris to talk about the company's genocidal AI chatbot Tay's public meltdown (13:00). Then, acting editor at Macworld.co.uk David Price jumps in to discuss the apparent resolution to the Apple vs FBI fight (29:00).  

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On this week's UK Tech Weekly podcast host Matt Egan is joined by Macworld UK and PC Advisor Staff Writer Lewis Painter, who has spent the past week in virtual reality, and is beyond excited to tell us all about the amazing HTC Vive. Then regular podder David Price, acting editor of Macworld UK, brings us tales from the murky world of Bitcoin, and explains how the crypto-currency is bringing about new tech that may revolutionise the finance industry (16:30) Finally, producer Chris throws aside his mic stand to discuss Sky Q and the current options in media streaming and TV. (25:30).  

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Matt Egan is back in the hosting chair to chat with producer Chris about the Samsung Galaxy Note 7 and how we feel about phablets. Techworld.com editor Charlotte Jee comes in to explain what is going on at the GDS (government digital service) and why we should care (13:00). Then online editor at Techworld.com Scott Carey chats Instagram stories, why it is a blatant rip off of Snapchat stories and how the social media giant can get away with being so brazen (22:00).  

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The team are back for the 34th episode of tech chat goodness as host ‘Mysterious’ David Price, acting Editor of Macworld UK invites Henry Burrell, Staff Writer at PC Advisor to talk about FIFA 17 and yearly game cycles. Next into the ring is Tamlin Magee (14 mins), Online Editor at ComputerWorld UK to discuss Oculus Rift’s Palmer Luckey and his odd meme-based support of Trump and the wider net of good-natured tech billionaires. Finally, Charlotte Jee (29 mins) Online Editor at Techworld lets us know why Elon Musk wants to sell you a ticket to space, and why it might actually be possible quite soon. Fill yer boots.  

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Matt Egan, Editorial Director, returns to lull us all into a tech talk dreamland of Peppa Pixels and magic Apple dragons. Chris Martin, Consumer Tech Editor at PC Advisor gives you the skinny on Google’s Pixel post-launch, and why it’s a shame it doesn’t resound as loudly as the affordable Nexus (got to love the Nexus 4, obvs). Then Acting Editor of Macworld UK David Price weeps into his cornflakes at the supposed demise of the humble USB port as Apple takes courage to new heights for the upcoming MacBook Pro (18 mins). Staff Writer at PC Advisor Christopher Minasians then lays down the law, rejoicing at the cutthroat prices of Nvidia’s new GTX 1050. Cheap as chips! In a good way. Tuck in (27 mins).  

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Host Henry Burrell leads the team into a tangle of nitty gritty tech topics in the penultimate pod of the year. Macworld UK Acting Editor David Price tells us why Apple and Nintendo very nearly scored a home run with Super Mario Run, but just missed out. The team, led by Charlotte Jee, Editor of Techworld then tackle Amazon's latest endeavour to solve first world problems (provided you live in Cambridge) (13 mins). Tamlin Magee, Online Editor at Techworld then leads us onto the sticky topic of defining extreme terror online and which big companies have a responsibility to police the Internet (27 mins).  

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Matt Egan hosts as we delve into the tech headlines of the week. Senior Staff Writer at PC Advisor Henry Burrell talks the gang through the latest on Samsung's upcoming smartphone and why it's been delayed, plus another brand comes back from the brink. Online Editor at Techworld Tamlin Magee then explores the strange but true story of Silicon Valley billionaires buying private islands with underground bunkers in case everything really does go Pete Tong. Finally Staff Writer at Macworld UK and PC Advisor Dominic Preston talks us through the frights of the latest Resident Evil game while everyone agrees they can be more terrifying than most horror films.  

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We finally get the IoT acronym the pod has been waiting for as we discuss Bitcoin and 17th century Dutch finance. Charlotte Jee informs Henry Burrell, David Price and Scott Carey.

Scott then leads us down the winding road of the so-called platform wars, in a week when Google blocked the Amazon Echo Show from streaming YouTube. Is this a bump in the road or will services be cut from rival hardware?

And finally, led by David, the pod discusses its favourite tech of the year and what you might consider buying for friends and family for Christmas.

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Back with a bang as Computerworld editor Scott Carey leads the squad into the cauldron of convo. Christina Mercer explains why her beau Elon Musk took a car into space, Sean Bradley on that bursting Bitcoin bubble, and David Price to tell us all how Apple can charge even more for its stuff and keep on making record profit.

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This week our host Scott Carey is joined by Macworld UK editor Karen Khan to chat about Apple's latest blockbuster results.

Then group production editor Tamlin Magee jumps in to discuss Amazon's working practices following the collective action around Prime Day.

Finally, Scott chats through his experience at the Google Cloud Next conference in San Francisco last week to see how it is trying to compete with the big boys at Amazon and Microsoft.

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This week on the UK Tech Weekly Podcast our host Scott Carey talks to Macworld editor David Price about the ever-controversial Alex Jones and why the big tech companies are finally stepping up their efforts to ban him from their platforms. Editors note: we recorded this on Thursday before Twitter finally started to take some measures against Jones, without outright banning him.

Next our resident phone nerd and consumer tech editor at Tech Advisor Henry Burrell talks about the upcoming Samsung Galaxy Note 9, the latest iPhone X rumours and how Apple and Google are trying to make you use your phone less.

Lastly Techworld editor Charlotte Jee takes us on a trip down memory lane to talk about the utopian vision of the Millennium Experience, how it reflected the values of a New Labour government and its legacy.

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Episode 101 is a second special in a row as we take tech to trial and consign our least favourite digital surplus to Room 101.

The Orwellian nightmare is compered by Henry Burrell as he, David Price, Tamlin Magee and Scott Carey each pick two things to banish forever. Cue a a bumper edition where we throw people, buzzwords, fads and entire companies down the trash chute.

May contain arguments.

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It's episode 105, and David Price takes on hosting duties as the team dissect the best and absolute worst of the week's tech developments.

Scott Carey talks us through the troubling and wide-ranging allegations of sexual misconduct at Google, and discusses how this relates to the tech industry's culture of protected privilege, and to the #metoo movement.

Then Henry Burrell, fresh from a briefing at Apple HQ, reports his distinctly positive first impressions of the iPhone XR, which he would gladly recommend to tech newbie grandmas, and also to Scott.

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David Price is in the host's chair this week, as the team talk about the latest hot tech topics. Tamlin Magee has got the drinks in - futuristic meal-replacement drinks called Soylent, which he forces everyone to try and which are apparently not people.

Then Dominic Preston talks us through the positive and extremely negative sides of Amazon's Black Friday activities, before Sean Bradley attempts to explain why Bitcoin is tanking and what the future holds for crypto currencies. Cheers!

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Happy New Year from the UK Tech Weekly Podcast!

We are back this week to discuss what we have been watching (or not watching) over the festive period, including Scott Carey on the meme-marketed sensation of Bird Box and what this says about Netflix's ability to dominate the cultural conversation. Then Tamlin Magee jumps in to talk about the interactive Black Mirror movie Bandersnatch and why it may have been destined to fail.

Lastly David Price steps out of the hosting chair to talk about bendy iPads and Apple's strange rhetoric.

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This article has been withdrawn by the authors as part of this review overlapped with the contents of Pietrangelo A and Ridgway ND. 2018. Cellular and Molecular Life Sciences. 75; 3079-98.

Inhibition of acid sphingomyelinase (ASM), a lysosomal enzyme that catalyzes the hydrolysis of sphingomyelin into ceramide and phosphorylcholine, may serve as an investigational tool or a therapeutic intervention to control many diseases. Specific ASM inhibitors are currently not sufficiently characterized. Here, we found that 1-aminodecylidene bis-phosphonic acid (ARC39) specifically and efficiently (>90%) inhibits both lysosomal and secretory ASM in vitro. Results from investigating sphingomyelin phosphodiesterase 1 (SMPD1/Smpd1) mRNA and ASM protein levels suggested that ARC39 directly inhibits ASM’s catalytic activity in cultured cells, a mechanism which differs from that of functional inhibitors of ASM (FIASMAs). We further provide evidence that ARC39 dose- and time-dependently inhibits lysosomal ASM in intact cells, and we show that ARC39 also reduces platelet- and ASMpromoted adhesion of tumor cells. The observed toxicity of ARC39 is low at concentrations relevant for ASM inhibition in vitro, and it does not strongly alter the lysosomal compartment or induce phospholipidosis in vitro. When applied intraperitoneally in vivo, even subtoxic high doses administered short-term induced sphingomyelin accumulation only locally in the peritoneal lavage without significant accumulation in plasma, liver, spleen or brain. These findings require further investigation with other possible chemical modifications. In conclusion, our results indicate that ARC39 potently and selectively inhibits ASM in vitro and highlight the need for developing compounds that can reach tissue concentrations sufficient for ASM inhibition in vivo.

Nutritional studies rely on various biological specimens for fatty acid (FA) determination, yet it is unclear how levels of serum non-esterified FA (NEFAs) correlate with other circulating lipid pools. Here, we used a high throughput method (< 4 min/sample) based on multisegment injection-non-aqueous-capillary electrophoresis–mass spectrometry (MSI-NACE-MS) to investigate whether specific serum NEFAs have utility as biomarkers of dietary fat intake in women. We first  identified circulating NEFAs correlated with long-term/habitual food intake among pregnant women with contrasting dietary patterns (n=50). Acute changes in serum NEFA trajectories were also studied in non-pregnant women (n=18) following high-dose (5 g/day) fish oil (FO) supplementation or isoenergetic sunflower oil placebo over 56 days. In the cross-sectional study, serum omega-3 (-3) FA correlated with self-reported total -3 daily intake, notably eicosapentaenoic acid (EPA) as its NEFA (r=0.46; p=0.001), whereas pentadecanoic acid was associated with full-fat dairy intake (r=0.43; p=0.002), outcomes consistent with results from  total FA serum hydrolysates. In the intervention cohort, serum -3 NEFAs increased 2.5-fold from baseline within 28 days following FO supplementation, and this increase was most pronounced for EPA (p=0.0004). Unlike for docosahexaenoic acid, circulating EPA as its NEFA also strongly correlated to EPA concentrations measured from erythrocyte phospholipid hydrolysates (r=0.66; p=4.6 x 10-10), and was better suited to detect dietary non-adherence. We conclude that MSI-NACE-MS offers a rapid method to quantify serum NEFAs and objectively monitor dietary fat intake in women that is complementary to diet records or food frequency questionnaires.

Atherogenic LDL particles are physicochemically and metabolically heterogeneous. Can bioactive lipid cargo differentiate LDL subclasses, and thus potential atherogenicity?  What is the effect of statin treatment? Obese, hypertriglyceridemic, hypercholesterolemic males (n=12; Lp(a) <10 mg/dL) received pitavastatin calcium (4mg/day) for 180 days in a single-phase, unblinded study. The lipidomic profiles (23 lipid classes) of five LDL subclasses fractionated from baseline and post-statin plasmas were determined by LC-MS. At baseline and on statin treatment, very small dense LDL (LDL5) was preferentially enriched (up to 3-fold) in specific lysophospholipids (lysophosphatidylcholine (LPC); lysophosphatidylinositol (LPI); lyso-platelet activating factor (LPC(O)); 9,0.2 and 0.14 mol/mol apoB respectively; all p<0.001 versus LDL1-4), suggesting  elevated inflammatory potential per particle. In contrast, lysophosphatidylethanolamine was uniformly distributed among LDL subclasses. Statin treatment markedly reduced absolute plasma concentrations of all LDL subclasses (up to 33.5%), including LPC, LPI and LPC(O) contents (up to -52%), consistent with reduction in cardiovascular risk. Despite such reductions, lipotoxic ceramide load per particle in LDL1-5 (1.5 - 3 mol/mol apoB; 3 - 7 mmol/mol phosphatidylcholine) was either conserved or elevated. Bioactive lipids may constitute biomarkers for the cardiometabolic risk associated with specific LDL subclasses in atherogenic dyslipidemia at baseline, and with residual risk on statin therapy.

Bis(monoacylglycero)phosphate (BMP), also known as lysobisphosphatidic acid (LBPA), is a phospholipid that promotes lipid sorting in late endosomes/lysosomes by activating lipid hydrolases and lipid transfer proteins. Changes in the cellular BMP content therefore reflect an altered metabolic activity of the endo-lysosomal system. Surprisingly, little is known about the physiological regulation of BMP. In this study, we investigated the effects of nutritional and metabolic factors on BMP profiles of whole tissues and  parenchymal and non-parenchymal cells. Tissue samples were obtained from fed, fasted, two-hours refed, and insulin-treated mice, as well as from mice housed at  5°C, 22°C, or 30°C. These tissues exhibited distinct BMP profiles, which were regulated by the nutritional state in a tissue-specific manner. Insulin treatment was not sufficient to mimic refeeding-induced changes in tissue BMP levels indicating that BMP metabolism is regulated by other hormonal or nutritional factors. Tissue fractionation experiments revealed that fasting drastically elevates BMP levels in hepatocytes and pancreatic cells. Furthermore, we observed that the BMP content in brown adipose tissue strongly depends on housing temperatures. In conclusion, our observations suggest that BMP concentrations adapt to the metabolic state in a tissue-and cell type-specific manner in mice. Drastic changes observed in hepatocytes, pancreatic cells, and brown adipocytes suggest that BMP possesses a role in the functional adaption to nutrient starvation and ambient temperature.

Multi-component lipid emulsions, rather than soy-oil emulsions, prevent cholestasis by an unknown mechanism. Here, we quantified liver function, bile acid pools, and gut microbial and metabolite profiles in premature, parenterally fed pigs given a soy-oil lipid emulsion, Intralipid (IL); a multi component lipid emulsion, SMOFlipid (SMOF); a novel emulsion with a modified fatty-acid composition (EXP); or a control enteral diet (ENT) for 22 days. We assayed serum cholestasis markers; measured total bile acid levels in plasma, liver, and gut contents; and analyzed colonic bacterial 16S rRNA gene sequences and metabolomic profiles. Serum cholestasis markers (i.e. bilirubin, bile acids, and g-glutamyl transferase) were highest in IL-fed pigs and normalized in those given SMOF, EXP, or ENT. Gut bile acid pools were lowest in the IL treatment and were increased in the SMOF and EXP treatments and comparable to ENT. Multiple bile acids, especially their conjugated forms, were higher in the colon contents of SMOF and EXP than in IL pigs. Colonic microbial communities of SMOF and EXP pigs had lower relative abundance of several Gram-positive anaerobes, including Clostridrium XIVa, and higher abundance of Enterobacteriaceae than those of IL and ENT pigs. Differences in lipid and microbial-derived compounds were also observed in colon metabolite profiles. These results indicate that multi-component lipid emulsions prevent cholestasis and restore enterohepatic bile flow in association with gut microbial and metabolomic changes. We conclude that sustained bile flow induced by multi-component lipid emulsions likely exerts a dominant effect in reducing bile acid–sensitive, Gram-positive bacteria.

Vitamin A aldehyde covalently bound to opsin protein is embedded in a phospholipid-rich membrane that supports photon absorption and phototransduction in photoreceptor cell outer segments. Following absorption of a photon, the 11-cis-retinal chromophore of visual pigment in photoreceptor cells isomerizes to all-trans-retinal. To maintain photosensitivity 11-cis-retinal must be replaced. At the same time, however, all-trans-retinal has to be handled so as to prevent nonspecific aldehyde activity. Some molecules of retinaldehyde upon release from opsin are efficiently reduced to retinol. Other molecules are released into the lipid phase of the disc membrane where they form a conjugate (N-retinylidene-PE, NRPE) through a Schiff base linkage with phosphatidylethanolamine (PE). The reversible formation of NRPE serves as a transient sink for retinaldehyde that is intended to return retinaldehyde to the visual cycle. However, if instead of hydrolyzing to PE and retinaldehyde, NRPE reacts with a second molecule of retinaldehyde a synthetic pathway is initiated that leads to the formation of multiple species of unwanted bisretinoid fluorophores. We report on recently identified members of the bisretinoid family some of which differ with respect to the acyl chains associated with the glycerol backbone. We discuss processing of the lipid moieties of these fluorophores in lysosomes of retinal pigment epithelial (RPE) cells, their fluorescence characters and new findings related to light and iron-associated oxidation of bisretinoids.

Sepsis is defined as the systemic, dysregulated host immune response to an infection that leads to injury to host organ systems, and, often, death. Complex interactions between pathogens and their hosts elicit microcirculatory dysfunction. Neutrophil myeloperoxidase (MPO) is critical for combating pathogens, but MPO-derived hypochlorous acid (HOCl) can react with host molecular species as well. Plasmalogens are targeted by HOCl, leading to the production of 2-chlorofatty acids (2-CLFAs). 2-CLFAs are associated with human sepsis mortality, decrease in vitroendothelial barrier function, and activate human neutrophil extracellular trap formation. Here, we sought to examine 2-CLFAs in an in vivorat sepsis model. Intraperitoneal cecal slurry sepsis with clinically relevant rescue therapies led to ~73% mortality and evidence of microcirculatory dysfunction. Plasma concentrations of 2-CLFAs assessed 8h after sepsis induction were lower in rats that survived sepsis than in non-survivors. 2-CLFA levels were elevated in kidney, liver, spleen, lung, colon and ileum in septic animals. In vivo, exogenous 2-CLFA treatments increased kidney permeability, and in in vitroexperiments 2-CLFA also increased epithelial surface expression of vascular cell adhesion molecule 1 and decreased epithelial barrier function. Collectively, these studies support a role of free 2-CLFAs as biomarkers of sepsis mortality, potentially mediated, in part, by 2-CLFA-elicited endothelial and epithelial barrier dysfunction.

1 April 2020

7 April 2020

Ankylosing Spondylitis (AS) is a common, inflammatory rheumatic disease, which primarily affects the axial skeleton and is associated with sacroiliitis, uveitis and enthesitis. Unlike other autoimmune rheumatic diseases, such as rheumatoid arthritis or systemic lupus erythematosus, autoantibodies have not yet been reported to be a feature of AS. We therefore wished to determine if plasma from patients with AS contained autoantibodies and if so, characterize and quantify this response in comparison to patients with Rheumatoid Arthritis (RA) and healthy controls. Two high-density nucleic acid programmable protein arrays expressing a total of 3498 proteins were screened with plasma from 25 patients with AS, 17 with RA and 25 healthy controls. Autoantigens identified were subjected to Ingenuity Pathway Analysis in order to determine patterns of signalling cascades or tissue origin. 44% of patients with Ankylosing Spondylitis demonstrated a broad autoantibody response, as compared to 33% of patients with RA and only 8% of healthy controls. Individuals with AS demonstrated autoantibody responses to shared autoantigens, and 60% of autoantigens identified in the AS cohort were restricted to that group. The AS patients autoantibody responses were targeted towards connective, skeletal and muscular tissue, unlike those of RA patients or healthy controls. Thus, patients with AS show evidence of systemic humoral autoimmunity and multispecific autoantibody production. Nucleic Acid Programmable Protein Arrays constitute a powerful tool to study autoimmune diseases.

Electrospray ionization is today the most widely used ionization technique in chemical and bio-chemical analysis. Interfaced with a mass spectrometer it allows to investigate the molecular composition of liquid samples. With electrospray a large variety of chemical substances can be ionized. There is no limitation in mass which enables even the investigation of large non-covalent protein complexes. Its high ionization efficiency profoundly changed bio-molecular sciences because proteins can be identified and quantified on trace amounts in a high throughput fashion. This review article focusses mainly on the exploration of the underlying ionization mechanism. Some ionization characteristics are discussed which are related to this mechanism. Typical spectra of peptides, proteins and non-covalent complexes are shown and the quantitative character of spectra is highlighted. Finally the possibilities and limitations in measuring the association constant of bivalent non-covalent complexes are described.

Ion mobility can add a dimension to LC-MS based shotgun proteomics which has the potential to boost proteome coverage, quantification accuracy and dynamic range.  Required for this is suitable software that extracts the information contained in the four-dimensional (4D) data space spanned by m/z, retention time, ion mobility and signal intensity. Here we describe the ion mobility enhanced MaxQuant software, which utilizes the added data dimension. It offers an end to end computational workflow for the identification and quantification of peptides and proteins in LC-IMS-MS/MS shotgun proteomics data. We apply it to trapped ion mobility spectrometry (TIMS) coupled to a quadrupole time-of-flight (QTOF) analyzer. A highly parallelizable 4D feature detection algorithm extracts peaks which are assembled to isotope patterns. Masses are recalibrated with a non-linear m/z, retention time, ion mobility and signal intensity dependent model, based on peptides from the sample. A new matching between runs (MBR) algorithm that utilizes collisional cross section (CCS) values of MS1 features in the matching process significantly gains specificity from the extra dimension. Prerequisite for using CCS values in MBR is a relative alignment of the ion mobility values between the runs. The missing value problem in protein quantification over many samples is greatly reduced by CCS aware MBR.MS1 level label-free quantification is also implemented which proves to be highly precise and accurate on a benchmark dataset with known ground truth. MaxQuant for LC-IMS-MS/MS is part of the basic MaxQuant release and can be downloaded from http://maxquant.org.

Drug resistance is a major obstacle to curative cancer therapies, and increased understanding of the molecular events contributing to resistance would enable better prediction of therapy response, as well as contribute to new targets for combination therapy. Here we have analyzed the early molecular response to epidermal growth factor receptor (EGFR) inhibition using RNA sequencing data covering 13 486 genes and mass spectrometry data covering 10 138 proteins. This analysis revealed a massive response to EGFR inhibition already within the first 24 hours, including significant regulation of hundreds of genes known to control downstream signaling, such as transcription factors, kinases, phosphatases and ubiquitin E3-ligases. Importantly, this response included upregulation of key genes in multiple oncogenic signaling pathways that promote proliferation and survival, such as ERBB3, FGFR2, JAK3 and BCL6, indicating an early adaptive response to EGFR inhibition. Using a library of more than 500 approved and experimental compounds in a combination therapy screen, we could show that several kinase inhibitors with targets including JAK3 and FGFR2 increased the response to EGFR inhibitors. Further, we investigated the functional impact of BCL6 upregulation in response to EGFR inhibition using siRNA-based silencing of BCL6. Proteomics profiling revealed that BCL6 inhibited transcription of multiple target genes including p53, resulting in reduced apoptosis which implicates BCL6 upregulation as a new EGFR inhibitor treatment escape mechanism. Finally, we demonstrate that combined treatment targeting both EGFR and BCL6 act synergistically in killing lung cancer cells. In conclusion, or data indicates that multiple different adaptive mechanisms may act in concert to blunt the cellular impact of EGFR inhibition, and we suggest BCL6 as a potential target for EGFR inhibitor-based combination therapy.

The onset of obesity-linked type 2 diabetes (T2D) is marked by an eventual failure in pancreatic β-cell function and mass that is no longer able to compensate for the inherent insulin resistance and increased metabolic load intrinsic to obesity. However, in a commonly used model of T2D, the db/db mouse, β-cells have an inbuilt adaptive flexibility enabling them to effectively adjust insulin production rates relative to the metabolic demand. Pancreatic β-cells from these animals have markedly reduced intracellular insulin stores, yet high rates of (pro)insulin secretion, together with a substantial increase in proinsulin biosynthesis highlighted by expanded rough endoplasmic reticulum and Golgi apparatus. However, when the metabolic overload and/or hyperglycemia is normalized, β-cells from db/db mice quickly restore their insulin stores and normalize secretory function. This demonstrates the β-cell’s adaptive flexibility and indicates that therapeutic approaches applied to encourage β-cell rest are capable of restoring endogenous β-cell function. However, mechanisms that regulate β-cell adaptive flexibility are essentially unknown. To gain deeper mechanistic insight into the molecular events underlying β-cell adaptive flexibility in db/db β-cells, we conducted a combined proteomic and post-translational modification specific proteomic (PTMomics) approach on islets from db/db mice and wild-type controls (WT) with or without prior exposure to normal glucose levels. We identified differential modifications of proteins involved in redox homeostasis, protein refolding, K48-linked deubiquitination, mRNA/protein export, focal adhesion, ERK1/2 signaling, and renin-angiotensin-aldosterone signaling, as well as sialyltransferase activity, associated with β-cell adaptive flexibility. These proteins are all related to proinsulin biosynthesis and processing, maturation of insulin secretory granules, and vesicular trafficking—core pathways involved in the adaptation of insulin production to meet metabolic demand. Collectively, this study outlines a novel and comprehensive global PTMome signaling map that highlights important molecular mechanisms related to the adaptive flexibility of β-cell function, providing improved insight into disease pathogenesis of T2D.

1 March 2007 , Number 6

The minister paused, leaned forward and fiddled with his cufflinks, ‘It wasn’t about whether the election was rigged or not,’ he said. ‘The truth is, everybody rigged it. We just rigged it better than them.’ Does the next Nigerian presidential election in April promise anything different?

1 March 2007 , Number 11

In early November, the retiring head of Britain’s Security Service MI5, Dame Eliza Manningham-Buller, warned that the danger of a terror attack was ‘serious’ and ‘growing’, with as many as thirty plots underway. Traditional terrorism of the sort practised by the Irish Republican Army has given way to the possibility, if not the expectation, that groups such as Al Qaeda might make use of chemical, biological, radiological and nuclear weapons and materials in an attack in Britain. So what are the dangers?

7 May 2020 , Volume 96, Number 3

7 May 2020 , Volume 96, Number 3

17 December 2019

How is it possible for the directors of the Russian economy to pursue an orthodox stabilization policy with a great measure of success and yet to have achieved so little to stem the growth slowdown? This paper examines the reasons for the divergence in economic management.

20 January 2020

How can democratic governments hold intelligence and security agencies to account when what they do is largely secret? Jamie Gaskarth explores how intelligence professionals view accountability in the context of 21st century politics. 

Invitation Only Research Event

Event participants

APOA5 is a low-abundance exchangeable apolipoprotein that plays critical roles in human triglyceride (TG) metabolism. Indeed, aberrations in the plasma concentration or structure of APOA5 are linked to hypertriglyceridemia, hyperchylomicronemia, myocardial infarction risk, obesity, and coronary artery disease. While it has been successfully produced at low yield in bacteria, the resulting protein had limitations for structure-function studies due to its low solubility under physiological buffer conditions. We hypothesized that the yield and solubility of recombinant APOA5 could be increased by: i) engineering a fusion protein construct in a codon optimized expression vector, ii) optimizing an efficient refolding protocol, and iii) screening buffer systems at physiological pH. The result was a high-yield (25 mg/l) bacterial expression system that produces lipid-free APOA5 soluble at concentrations of up to 10 mg/ml at a pH of 7.8 in bicarbonate buffers. Physical characterization of lipid-free APOA5 indicated that it exists as an array of multimers in solution, and far UV circular dichroism analyses show differences in total α-helicity between acidic and neutral pH buffering conditions. The protein was functional in that it bound and emulsified multilamellar dimyristoyl-phosphatidylcholine vesicles and could inhibit postprandial plasma TG accumulation when injected into C57BL/6J mice orally gavaged with Intralipid.

Bile acids (BAs) serve multiple biological functions, ranging from the absorption of lipids and fat-soluble vitamins to serving as signaling molecules through the direct activation of dedicated cellular receptors. Synthesized by both host and microbial pathways, BAs are increasingly understood as participating in the regulation of numerous pathways relevant to metabolic diseases, including lipid and glucose metabolism, energy expenditure, and inflammation. Quantitative analyses of BAs in biological matrices can be problematic due to their unusual and diverse physicochemical properties, making optimization of a method that shows good accuracy, precision, efficiency of extraction, and minimized matrix effects across structurally distinct human and murine BAs challenging. Herein we develop and clinically validate a stable-isotope-dilution LC/MS/MS method for the quantitative analysis of numerous primary and secondary BAs in both human and mouse biological matrices. We also utilize this tool to investigate gut microbiota participation in the generation of structurally specific BAs in both humans and mice. We examine circulating levels of specific BAs and in a clinical case-control study of age- and gender-matched type 2 diabetes mellitus (T2DM) versus nondiabetics. BAs whose circulating levels are associated with T2DM include numerous 12α-hydroxyl BAs (taurocholic acid, taurodeoxycholic acid, glycodeoxycholic acid, deoxycholic acid, and 3-ketodeoxycholic acid), while taurohyodeoxycholic acid was negatively associated with diabetes. The LC/MS/MS-based platform described should serve as a robust, high-throughput investigative tool for studying the potential involvement of structurally specific BAs and the gut microbiome on both physiological and disease processes.

Cholesteryl ester transfer protein (CETP) exists as full-length (FL) and exon 9 (E9)-deleted isoforms. The function of E9-deleted CETP is poorly understood. Here, we investigated the role of E9-deleted CETP in regulating the secretion of FL-CETP by cells and explored its possible role in intracellular lipid metabolism. CETP overexpression in cells that naturally express CETP confirmed that E9-deleted CETP is not secreted, and showed that cellular FL- and E9-deleted CETP form an isolatable complex. Coexpression of CETP isoforms lowered cellular levels of both proteins and impaired FL-CETP secretion. These effects were due to reduced synthesis of both isoforms; however, the predominate consequence of FL- and E9-deleted CETP coexpression is impaired FL-CETP synthesis. We reported previously that reducing both CETP isoforms or overexpressing FL-CETP impairs cellular triglyceride (TG) storage. To investigate this further, E9-deleted CETP was expressed in SW872 cells that naturally synthesize CETP and in mouse 3T3-L1 cells that do not. E9-deleted CETP overexpression stimulated SW872 triglyceride synthesis and increased stored TG 2-fold. Expression of E9-deleted CETP in mouse 3T3-L1 cells produced a similar lipid phenotype. In vitro, FL-CETP promotes the transfer of TG from ER-enriched membranes to lipid droplets. E9-deleted CETP also promoted this transfer, although less effectively, and it inhibited the transfer driven by FL-CETP. We conclude that FL- and E9-deleted CETP isoforms interact to mutually decrease their intracellular levels and impair FL-CETP secretion by reducing CETP biosynthesis. E9-deleted CETP, like FL-CETP, alters cellular TG metabolism and storage but in a contrary manner.

Obesity, dyslipidemia, and insulin resistance, the increasingly common metabolic syndrome, are risk factors for CVD and type 2 diabetes that warrant novel therapeutic interventions. The flavonoid nobiletin displays potent lipid-lowering and insulin-sensitizing properties in mice with metabolic dysfunction. However, the mechanisms by which nobiletin mediates metabolic protection are not clearly established. The central role of AMP-activated protein kinase (AMPK) as an energy sensor suggests that AMPK is a target of nobiletin. We tested the hypothesis that metabolic protection by nobiletin required phosphorylation of AMPK and acetyl-CoA carboxylase (ACC) in mouse hepatocytes, in mice deficient in hepatic AMPK (Ampkβ1^–/–), in mice incapable of inhibitory phosphorylation of ACC (AccDKI), and in mice with adipocyte-specific AMPK deficiency (iβ1β2AKO). We fed mice a high-fat/high-cholesterol diet with or without nobiletin. Nobiletin increased phosphorylation of AMPK and ACC in primary mouse hepatocytes, which was associated with increased FA oxidation and attenuated FA synthesis. Despite loss of ACC phosphorylation in Ampkβ1^–/– hepatocytes, nobiletin suppressed FA synthesis and enhanced FA oxidation. Acute injection of nobiletin into mice did not increase phosphorylation of either AMPK or ACC in liver. In mice fed a high-fat diet, nobiletin robustly prevented obesity, hepatic steatosis, dyslipidemia, and insulin resistance, and it improved energy expenditure in Ampkβ1^–/–, AccDKI, and iβ1β2AKO mice to the same extent as in WT controls. Thus, the beneficial metabolic effects of nobiletin in vivo are conferred independently of hepatic or adipocyte AMPK activation. These studies further underscore the therapeutic potential of nobiletin and begin to clarify possible mechanisms.

Liver-derived serum amyloid A (SAA) is present in plasma where it is mainly associated with HDL and from which it is cleared more rapidly than are the other major HDL-associated apolipoproteins. Although evidence suggests that lipid-free and HDL-associated forms of SAA have different activities, the pathways by which SAA associates and disassociates with HDL are poorly understood. In this study, we investigated SAA lipidation by hepatocytes and how this lipidation relates to the formation of nascent HDL particles. We also examined hepatocyte-mediated clearance of lipid-free and HDL-associated SAA. We prepared hepatocytes from mice injected with lipopolysaccharide or an SAA-expressing adenoviral vector. Alternatively, we incubated primary hepatocytes from SAA-deficient mice with purified SAA. We analyzed conditioned media to determine the lipidation status of endogenously produced and exogenously added SAA. Examining the migration of lipidated species, we found that SAA is lipidated and forms nascent particles that are distinct from apoA-I-containing particles and that apoA-I lipidation is unaltered when SAA is overexpressed or added to the cells, indicating that SAA is not incorporated into apoA-I-containing HDL during HDL biogenesis. Like apoA-I formation, generation of SAA-containing particles was dependent on ABCA1, but not on scavenger receptor class B type I. Hepatocytes degraded significantly more SAA than apoA-I. Taken together, our results indicate that SAA’s lipidation and metabolism by the liver is independent of apoA-I and that SAA is not incorporated into HDL during HDL biogenesis.