Ning Zhang, Jia Wu and Liwei Zhang
Math. Comp. 89 (2020), 1867-1894.
Abstract, references and article information

The proptech startup wanted to democratise investment in prime real estate projects through crowdfunding, but government regulations have limited its reach to high net worth individuals

Startups moving to the scale-up phase will naturally experience growing pains, here's how to manage your team through that period with as little disruption as possible

The confidence level of Hong Kong’s exporters has fallen to its lowest-ever level in the face of a triple challenge – the COVID-19 outbreak, softening global demand and lingering trade tension between the United States and Mainland...

Secretary for the Civil Service Patrick Nip today visited the Inland Revenue Department and the Labour Department to inspect the resumption of public services.

The Government had earlier announced that public services will be resumed under a phased approach.

Counter services of most government departments have returned to normal.

Mr Nip first visited the Inland Revenue Department in Revenue Tower and was briefed on counter services at the Central Enquiry Counter, the Business Registration Office and the Stamp Office.

He learnt that the department has implemented various infection control and crowd management measures, such as a ticketing system, to safeguard the health of colleagues and the public.

Later Mr Nip visited the Hong Kong East Job Centre and a recruitment centre for the catering and retail industries and was briefed on the resumption of normal services at the Labour Department's job and recruitment centres.

He said: “While maintaining a high degree of vigilance and adopting all necessary precautionary measures, the Government gradually resumed public services today in a smooth and orderly manner.

“Various infection control measures have been put in place at government buildings and offices. These include checking the body temperature of persons at entrances, providing alcohol-based hand sanitiser and enhancing the cleaning of public facilities.

“The Government will closely monitor the situation to determine when to embark on full resumption of normal business.”

Secretary for Innovation & Technology Alfred Sit today met representatives of the Hong Kong Science & Technology Parks Corporation (HKSTPC) and research and development centres (R&D) specialising in innovations winning recognition worldwide.

While touring the Hong Kong Science Park, Mr Sit visited the Hong Kong Applied Science & Technology Research Institute, the Logistics & Supply Chain MultiTech R&D Centre, the Nano & Advanced Materials Institute and HKSTPC.

He met representatives of HKSTPC start-ups that specialise in healthcare technology, artificial intelligence, chips, material science and vehicle safety technology. Some start-ups have participated in the StayHomeSafe mobile app.

Mr Sit noted that Science Park is a breeding ground for local innovation and technology that shows tremendous strength.

He emphasised that with the concerted efforts of the HKSTPC and all R&D centres, batches of R&D talent have been nurtured, with their innovations winning recognition worldwide.

Their work has also helped consolidate Hong Kong's R&D strengths, promote applied R&D and foster commercialisation of R&D results, he added.

On the application of technology solutions in fighting the COVID-19 pandemic, the secretary pointed out that the electronic wristbands and StayHomeSafe mobile app used for home quarantine arrangements, the NASK Nanofiber Smart Mask supplied to the Hospital Authority and the CuMask are all R&D achievements from Science Park.

Mr Sit said he hoped that with the collaborative efforts of the HKSTPC and R&D centres, the I&T development in Hong Kong will be further promoted, driving economic development and improving people's livelihood.

Secretary for Financial Services & the Treasury Christopher Hui today visited the Companies Registry (CR) to inspect its operation.

Mr Hui visited the New Companies Section, the Public Search Section and the Document Management Section at the registry and spoke with staff there to learn about their work conditions and the services that they provide.

He said: “The COVID-19 pandemic has dealt a heavy blow to Hong Kong's overall economy.

“To help enterprises cope with their operating pressure amid the economic downturn, the Financial Secretary announced in the 2020-21 Budget the waiver of registration fees for annual returns, except for late delivery, charged by the CR for two years.

“And with a view to encouraging the wider use of the CR's electronic services, we also propose to reduce the fees payable in relation to the incorporation of companies, including registration of non-Hong Kong companies, through electronic means by 10%."

The Companies (Fees) (Amendment) Regulation 2020 gazetted today will be tabled at the Legislative Council for negative vetting on May 13 for the waiver and reduction to take effect from October 1.

The waiver of registration fees for annual returns will benefit about 1.4 million companies.

Mr Hui added that he was pleased that the CR has been providing electronic services for filing of documents and company searches.

He appealed to the department to adopt wider use of technology, adding that a business-friendly environment is needed more than ever in the process of economic recovery.

Mr Hui also expressed gratitude to CR staff for their dedication in providing public services amid the pandemic.

Secretary for Home Affairs Caspar Tsui visited the Physical Fitness Association of Hong Kong, China today to inspect its work in implementing the Fitness Centre Subsidy Scheme launched under the second phase of the Anti-epidemic Fund.

Mr Tsui said the scheme aims to provide a one-off subsidy of $100,000 to fitness centres to tide businesses over financial difficulties arising from anti-epidemic measures.

He thanked the association for handling the scheme’s applications.

Mr Tsui also expressed gratitude to the fitness industry for complying with the Government’s preventive measures, including suspension of business, in the fight against the virus.

Given the stabilising epidemic situation, the Government has conducted a health risk assessment and will allow premises, including fitness centres, to resume operations, Mr Tsui said, adding that he hopes the fitness industry will soon regain vitality.

The Home Affairs Bureau commissioned the association to assist in implementing the scheme, which opened for applications on May 4.

As of May 7, the association received 397 applications, of which more than half of them have been initially found to be eligible, involving subsidies of about $20 million.

The application period for the scheme will end on June 3.

Call 2302 9089 or send an email for enquiries.

Previous studies have shown that sphingosine kinase interacting protein (SKIP) inhibits sphingosine kinase (SK) function in fibroblasts. SK phosphorylates sphingosine producing the potent signaling molecule sphingosine-1-phosphate (S1P). SKIP gene (SPHKAP) expression is silenced by hypermethylation of its promoter in acute myeloid leukemia (AML). However, why SKIP activity is silenced in primary AML cells is unclear. Here, we investigated the consequences of SKIP down-regulation in AML primary cells and the effects of SKIP re-expression in leukemic cell lines. Using targeted ultra-HPLC-tandem MS (UPLC-MS/MS), we measured sphingolipids (including S1P and ceramides) in AML and control cells. Primary AML cells had significantly lower SK activity and intracellular S1P concentrations than control cells, and SKIP-transfected leukemia cell lines exhibited increased SK activity. These findings show that SKIP re-expression enhances SK activity in leukemia cells. Furthermore, other bioactive sphingolipids such as ceramide were also down-regulated in primary AML cells. Of note, SKIP re-expression in leukemia cells increased ceramide levels 2-fold, inactivated the key signaling protein extracellular signal-regulated kinase, and increased apoptosis following serum deprivation or chemotherapy. These results indicate that SKIP down-regulation in AML reduces SK activity and ceramide levels, an effect that ultimately inhibits apoptosis in leukemia cells. The findings of our study contrast with previous results indicating that SKIP inhibits SK function in fibroblasts and therefore challenge the notion that SKIP always inhibits SK activity.

Cytochrome c oxidase (CcO) reduces O2 to water, coupled with a proton-pumping process. The structure of the O2-reduction site of CcO contains two reducing equivalents, Fea32+ and CuB1+, and suggests that a peroxide-bound state (Fea33+–O−–O−–CuB2+) rather than an O2-bound state (Fea32+–O2) is the initial catalytic intermediate. Unexpectedly, however, resonance Raman spectroscopy results have shown that the initial intermediate is Fea32+–O2, whereas Fea33+–O−–O−–CuB2+ is undetectable. Based on X-ray structures of static noncatalytic CcO forms and mutation analyses for bovine CcO, a proton-pumping mechanism has been proposed. It involves a proton-conducting pathway (the H-pathway) comprising a tandem hydrogen-bond network and a water channel located between the N- and P-side surfaces. However, a system for unidirectional proton-transport has not been experimentally identified. Here, an essentially identical X-ray structure for the two catalytic intermediates (P and F) of bovine CcO was determined at 1.8 Å resolution. A 1.70 Å Fe–O distance of the ferryl center could best be described as Fea34+ = O2−, not as Fea34+–OH−. The distance suggests an ∼800-cm−1 Raman stretching band. We found an interstitial water molecule that could trigger a rapid proton-coupled electron transfer from tyrosine-OH to the slowly forming Fea33+–O−–O−–CuB2+ state, preventing its detection, consistent with the unexpected Raman results. The H-pathway structures of both intermediates indicated that during proton-pumping from the hydrogen-bond network to the P-side, a transmembrane helix closes the water channel connecting the N-side with the hydrogen-bond network, facilitating unidirectional proton-pumping during the P-to-F transition.

S-Palmitoylation is a reversible post-translational lipid modification that dynamically regulates protein functions. Voltage-gated sodium channels are subjected to S-palmitoylation and exhibit altered functions in different S-palmitoylation states. Our aim was to investigate whether and how S-palmitoylation regulates Nav1.6 channel function and to identify S-palmitoylation sites that can potentially be pharmacologically targeted. Acyl-biotin exchange assay showed that Nav1.6 is modified by S-palmitoylation in the mouse brain and in a Nav1.6 stable HEK 293 cell line. Using whole-cell voltage clamp, we discovered that enhancing S-palmitoylation with palmitic acid increases Nav1.6 current, whereas blocking S-palmitoylation with 2-bromopalmitate reduces Nav1.6 current and shifts the steady-state inactivation in the hyperpolarizing direction. Three S-palmitoylation sites (Cys1169, Cys1170, and Cys1978) were identified. These sites differentially modulate distinct Nav1.6 properties. Interestingly, Cys1978 is exclusive to Nav1.6 among all Nav isoforms and is evolutionally conserved in Nav1.6 among most species. Cys1978 S-palmitoylation regulates current amplitude uniquely in Nav1.6. Furthermore, we showed that eliminating S-palmitoylation at specific sites alters Nav1.6-mediated excitability in dorsal root ganglion neurons. Therefore, our study reveals S-palmitoylation as a potential isoform-specific mechanism to modulate Nav activity and neuronal excitability in physiological and diseased conditions.

We previously reported that overexpression of cytochrome P450 family 24 subfamily A member 1 (CYP24A1) increases lung cancer cell proliferation by activating RAS signaling and that CYP24A1 knockdown inhibits tumor growth. However, the mechanism of CYP24A1-mediated cancer cell proliferation remains unclear. Here, we conducted cell synchronization and biochemical experiments in lung adenocarcinoma cells, revealing a link between CYP24A1 and anaphase-promoting complex (APC), a key cell cycle regulator. We demonstrate that CYP24A1 expression is cell cycle–dependent; it was higher in the G2-M phase and diminished upon G1 entry. CYP24A1 has a functional destruction box (D-box) motif that allows binding with two APC adaptors, CDC20-homologue 1 (CDH1) and cell division cycle 20 (CDC20). Unlike other APC substrates, however, CYP24A1 acted as a pseudo-substrate, inhibiting CDH1 activity and promoting mitotic progression. Conversely, overexpression of a CYP24A1 D-box mutant compromised CDH1 binding, allowing CDH1 hyperactivation, thereby hastening degradation of its substrates cyclin B1 and CDC20, and accumulation of the CDC20 substrate p21, prolonging mitotic exit. These activities also occurred with a CYP24A1 isoform 2 lacking the catalytic cysteine (Cys-462), suggesting that CYP24A1's oncogenic potential is independent of its catalytic activity. CYP24A1 degradation reduced clonogenic survival of mutant KRAS-driven lung cancer cells, and calcitriol treatment increased CYP24A1 levels and tumor burden in Lsl-KRASG12D mice. These results disclose a catalytic activity-independent growth-promoting role of CYP24A1 in mutant KRAS-driven lung cancer. This suggests that CYP24A1 could be therapeutically targeted in lung cancers in which its expression is high.

Chief Executive Carrie Lam today visited Tai Mo Shan Country Park to inspect its management services amid the COVID-19 epidemic.

She was accompanied by Secretary for the Environment KS Wong and Director of Agriculture, Fisheries & Conservation Dr Leung Siu-fai.

Mrs Lam visited personnel working at the park’s visitor centre and Twisk Country Park Management Centre of Tai Lam Country Park.

She observed how they enhanced campsites and associated facilities, improved hiking trails with natural materials, provided more lookout points for people to enjoy the scenery and strengthened services at visitor centres.

Mrs Lam learnt about the department’s anti-epidemic measures and management work, including running temperature checks on all park visitors.

Noting that the number of visitors in various country parks increased by 25% in February, Mrs Lam praised staff for their commitment to strengthening anti-epidemic work to safeguard public health.

The department enhanced its promotions and public education on anti-epidemic measures and protecting the environment through various means including social media and the networks of partner organisations.

Mrs Lam also visited a refreshment kiosk to learn about its business.

The department has provided rent concessions to all kiosks in country parks and will extend such relief measures until September this year to help shop operators during these difficult times. 

Mrs Lam said she appreciated the kiosk’s efforts to protect the environment and reduce waste and disposable plastics, which encourages people to adopt a greener lifestyle.

She also appealed to the public to exercise social distancing while enjoying the countryside amid the epidemic.

(University of Barcelona) The yellow-legged gull has a high ability to adapt to human activities and benefit from these as a food resource during all year. This is stated in a scientific article published in the journal Ecology and Evolution whose first author is the researcher Francisco Ramírez, from the Faculty of Biology and the Biodiversity Research Institute (IRBio) of the University of Barcelona.

(American Marketing Association) Nonprofits may better meet their missions by learning to effectively employ the entirety of the marketing mix to attract individuals to available donation opportunities.

(American Association for the Advancement of Science) High-resolution images and video were taken by the Japanese space agency's Hayabusa2 spacecraft as it briefly landed to collect samples from Ryugu -- a nearby asteroid that orbits mostly between Earth and Mars -- allowing researchers to get an up-close look at its rocky surface, according to a new report.

(Kessler Foundation) Andrew Houtenville, Ph.D., research director of the University of New Hampshire's Institute on Disability: 'Unlike the Great Recession and the Great Depression, many workers in the COVID Recession may be 'on temporary layoff' (aka furloughed) and may be recalled, rather than losing their jobs completely. To further investigate this issue, we plan to release a Special nTIDE Report on May 15.'

(Oregon State University) Clinical trial data behind drug dose recommendations for elevated cholesterol and chronic obstructive pulmonary disease illustrate how larger doses may not be worth the extra costs for many types of patients.

Back in January when dancehall artiste Govana released the track HAMANTS Convo, the storyline captivated listeners across the globe. For weeks, the song, which highlights infidelity in relationships, trended at number one on the local YouTube...

Many may remember Natel from the Digicel Rising Stars competition back in 2005. The singer was a runner-up that year and has been working to set himself apart in the music industry ever since. It has been 15 years, and although his name may not be...

15 October 2018

26 February 2020

¹⁸F-PI-2620 is a next generation tau positron emission tomography (PET)-tracer that has demonstrated ability to image the spatial distribution of suspected tau pathology. The objective of this study was to assess the tracer biodistribution, dosimetry and quantitative methods of ¹⁸F-PI-2620 in the human brain. Full kinetic modelling approaches to quantify tau load were investigated. Non-invasive kinetic modeling approaches and semi-quantitative methods were evaluated against the full tracer kinetics. Finally, the reproducibility of PET measurements from test and retest scans was assessed. Methods: Three healthy controls (HC) and 4 Alzheimer disease (AD) subjects underwent two dynamic PET scans including arterial sampling. Distribution volume ratio (DVR) was estimated using full tracer kinetics (2 Tissue Compartment (2TC) models, Logan Graphical Analysis (LGA)) and non-invasive kinetic models (Non-Invasive Logan Graphical Analysis (NI-LGA) and the multilinear reference tissue model (MRTM2)). Standardized uptake value ratio (SUVR) was determined at different imaging windows after injection. Correlation between DVR and SUVR, effect size (Cohen’s d) and test-retest variability (TRV) were evaluated. Additionally, 6 HC subjects received one tracer administration and underwent whole-body PET for dosimetry calculation. Organ doses and the whole-body effective dose were calculated using OLINDA 2.0. Results: Strong correlation was found across different kinetic models (R2 >0.97) and between DVR(2TC) and SUVRs between 30 to 90 min with R2>0.95. Secular equilibrium was reached around 40 min post injection (p.i.) in most regions and subjects. The TRV and effect size for the SUVR across different regions was similar at 30-60 min (TRV=3.8%, d=3.80), 45-75 min (TRV=4.3%, d=3.77) and 60-90 min (TRV=4.9%, d=3.73) and increased at later time points. Elimination was via the hepatobiliary and urinary system. The whole-body effective dose was determined to be 33.3±2.1 μSv/MBq for an adult female and 33.1±1.4 μSv/MBq for an adult male with a 1.5 hour urinary bladder voiding interval. Conclusion: ¹⁸F-PI-2620 exhibits fast kinetics, suitable dosimetry and low TRV. DVR measured using the 2TC model with arterial sampling correlated strongly with DVR measured by NI-LGA, MRTM2 and SUVR. SUVR can be used for ¹⁸F-PI-2620 PET quantification of tau deposits avoiding arterial blood sampling. Static ¹⁸F-PI-2620 PET scans between 45-75min p.i. provide excellent quantification accuracy, large effect size and low TRV.

[S-Methyl-¹¹C](±)-7-methoxy-3-(4-(4-(methylthio)phenyl)butyl)-2,3,4,5-tetrahydro-1H-benzo[d]azepin-1-ol (¹¹C-NR2B-SMe) and its enantiomers were synthesized as candidates for imaging the NR2B subunit within the N-methyl-D-aspartate receptor with positron emission tomography (PET). Methods: Brains were scanned with PET for 90 min after intravenous injection of one of the candidate radioligands into rats. To detect any NR2B specific binding of radioligand in brain, various pre-blocking or displacing agents were evaluated for their impact on the PET brain imaging data. Radiometabolites from brain and other tissues were measured ex vivo and in vitro. Results: Each radioligand gave high early whole brain uptake of radioactivity, followed by a brief fast decline and then a slow final decline. ¹¹C-(S)-NR2B-SMe was studied extensively. Ex vivo measurements showed that radioactivity in rat brain at 30 min after radioligand injection was virtually unchanged radioligand. Only less lipophilic radiometabolites appeared in plasma. High-affinity NR2B ligands, Ro-25-6981, ifenprodil, and CO10124, showed increasing preblock of whole brain radioactivity retention with increasing dose (0.01 to 1.25 mg/kg, i.v.). Five 1 antagonists (FTC146, BD1407, F3, F4, and NE100) and four 1 agonists ((+)-pentazocine, (±)-PPCC, PRE-084, (+)-SKF10047) were ineffective preblocking agents, except FTC146 and F4 at high dose. Two potent 1 receptor agonists, TC1 and SA4503, showed dose-dependent preblocking effects in the presence or absence of pharmacological 1 receptor blockade with FTC146. Conclusion: ¹¹C-(S)-NR2B-SMe has adequate NR2B-specific PET signal in rat brain to warrant further evaluation in higher species. TC1 and SA4503 likely have off-target binding to NR2B in vivo.

4 December 2019

Research Event

Event participants

HE Nabil Ben Khedher, Ambassador of Tunisia to the United Kingdom
Professor Naohiro Kitano, Visiting Fellow, Japan International Cooperation Agency Research Institute (JICA-RI); Professor, Waseda University
Taku Miyazaki, Deputy Director General, Japan External Trade Organisation (JETRO) London
Serge Mouangue, Founder and Art Director, WAfrica
Norio Suzuki, Senior Strategist, BBOXX
HE Professor Mohammed Gana Yisa, Ambassador of the Federal Republic of Nigeria to Japan; Chairman, African Diplomatic Corps in Tokyo (ADC) TICAD Committee

Chairs:
Dr Champa Patel, Director, Asia-Pacific Programme, Chatham House
Dr Alex Vines OBE, Managing Director, Ethics, Risk & Resilience; Director, Africa Programme

Previous studies have shown that sphingosine kinase interacting protein (SKIP) inhibits sphingosine kinase (SK) function in fibroblasts. SK phosphorylates sphingosine producing the potent signaling molecule sphingosine-1-phosphate (S1P). SKIP gene (SPHKAP) expression is silenced by hypermethylation of its promoter in acute myeloid leukemia (AML). However, why SKIP activity is silenced in primary AML cells is unclear. Here, we investigated the consequences of SKIP down-regulation in AML primary cells and the effects of SKIP re-expression in leukemic cell lines. Using targeted ultra-HPLC-tandem MS (UPLC-MS/MS), we measured sphingolipids (including S1P and ceramides) in AML and control cells. Primary AML cells had significantly lower SK activity and intracellular S1P concentrations than control cells, and SKIP-transfected leukemia cell lines exhibited increased SK activity. These findings show that SKIP re-expression enhances SK activity in leukemia cells. Furthermore, other bioactive sphingolipids such as ceramide were also down-regulated in primary AML cells. Of note, SKIP re-expression in leukemia cells increased ceramide levels 2-fold, inactivated the key signaling protein extracellular signal-regulated kinase, and increased apoptosis following serum deprivation or chemotherapy. These results indicate that SKIP down-regulation in AML reduces SK activity and ceramide levels, an effect that ultimately inhibits apoptosis in leukemia cells. The findings of our study contrast with previous results indicating that SKIP inhibits SK function in fibroblasts and therefore challenge the notion that SKIP always inhibits SK activity.

Gemma Cadby
Apr 1, 2020; 61:537-545
Patient-Oriented and Epidemiological Research

Mustafa Yalcinkaya
Apr 1, 2020; 61:492-504
Research Articles

In this week's fiery episode host Matt Egan talks war and gaming with Macworld UK's David Price, the greatest graphics ever with Christopher Minasians of PC Advisor and Macworld UK (14:21), and the best networks in the UK with fellow PCA and MWUK stalwart Henry Burrell (25:23). Expect songs and laughter, and tech ever after.  

See acast.com/privacy for privacy and opt-out information.

Allow Matt Egan (and Shed7) to lull you into this week's pod as we tackle the big tech issues of the week. Staff Writer at Digital Arts Miriam Harris explains the latest HR and PR mess over at Uber. How long will consumers use a service when the company are clearly not treating its staff well? Then (16:30) Deputy Editor of Macworld UK David Price gets excited about Apple Park, the so-called 'spaceship campus' that has been under construction for years. May contain orchards. Finally (26:48) Senior Staff Writer at Tech Advisor Henry Burrell previews Mobile World Congress which gets underway on 26th February. Are any of the major handset launches worth your attention?  

See acast.com/privacy for privacy and opt-out information.

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.

16 March 2020

6 May 2020

Invitation Only Research Event

Event participants

Oscar Jonsson, Director, Stockholm Free World Forum (Frivärld)
Mathieu Boulègue, Research Fellow, Russia and Eurasia Programme, Chatham House
Chair: ​Alice Billon-Galland, Research Associate, Europe Programme, Chatham House

Whether HDL is associated with dementia risk is unclear. In addition to apoA1, other apolipoproteins are found in HDL, creating subspecies of HDL that may have distinct metabolic properties. We measured apoA1, apoC3, and apoJ levels in plasma and apoA1 levels in HDL that contains or lacks apoE, apoJ, or apoC3 using a modified sandwich ELISA in a case-cohort study nested within the Ginkgo Evaluation of Memory Study. We included 995 randomly selected participants and 521 participants who developed dementia during a mean of 5.1 years of follow-up. The level of total apoA1 was not significantly related to dementia risk, regardless of the coexistence of apoC3, apoJ, or apoE. Higher levels of total plasma apoC3 were associated with better cognitive function at baseline (difference in Modified Mini-Mental State Examination scores tertile 3 vs. tertile 1: 0.60; 95% CI: 0.23, 0.98) and a lower dementia risk (adjusted hazard ratio tertile 3 vs. tertile 1: 0.73; 95% CI: 0.55, 0.96). Plasma concentrations of apoA1 in HDL and its apolipoprotein-defined subspecies were not associated with cognitive function at baseline or with the risk of dementia during follow-up. Similar studies in other populations are required to better understand the association between apoC3 and Alzheimer’s disease pathology.

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.

CVD is the leading cause of death worldwide, and genetic investigations into the human lipidome may provide insight into CVD risk. The aim of this study was to estimate the heritability of circulating lipid species and their genetic correlation with CVD traits. Targeted lipidomic profiling was performed on 4,492 participants from the Busselton Family Heart Study to quantify the major fatty acids of 596 lipid species from 33 classes. We estimated narrow-sense heritabilities of lipid species/classes and their genetic correlations with eight CVD traits: BMI, HDL-C, LDL-C, triglycerides, total cholesterol, waist-hip ratio, systolic blood pressure, and diastolic blood pressure. We report heritabilities and genetic correlations of new lipid species/subclasses, including acylcarnitine (AC), ubiquinone, sulfatide, and oxidized cholesteryl esters. Over 99% of lipid species were significantly heritable (h²: 0.06–0.50) and all lipid classes were significantly heritable (h²: 0.14–0.50). The monohexosylceramide and AC classes had the highest median heritabilities (h² = 0.43). The largest genetic correlation was between clinical triglycerides and total diacylglycerol (r_g = 0.88). We observed novel positive genetic correlations between clinical triglycerides and phosphatidylglycerol species (r_g: 0.64–0.82), and HDL-C and alkenylphosphatidylcholine species (r_g: 0.45–0.74). Overall, 51% of the 4,768 lipid species-CVD trait genetic correlations were statistically significant after correction for multiple comparisons. This is the largest lipidomic study to address the heritability of lipids and their genetic correlation with CVD traits. Future work includes identifying putative causal genetic variants for lipid species and CVD using genome-wide SNP and whole-genome sequencing data.

Loss of pancreatic β-cell mass and function as a result of sustained ER stress is a core step in the pathogenesis of diabetes mellitus type 2. The complex control of β-cells and insulin production involves hedgehog (Hh) signaling pathways as well as cholesterol-mediated effects. In fact, data from studies in humans and animal models suggest that HDL protects against the development of diabetes through inhibition of ER stress and β-cell apoptosis. We investigated the mechanism by which HDL inhibits ER stress and apoptosis induced by thapsigargin, a sarco/ER Ca²⁺-ATPase inhibitor, in β-cells of a rat insulinoma cell line, INS1e. We further explored effects on the Hh signaling receptor Smoothened (SMO) with pharmacologic agonists and inhibitors. Interference with sterol synthesis or efflux enhanced β-cell apoptosis and abrogated the anti-apoptotic activity of HDL. During ER stress, HDL facilitated the efflux of specific oxysterols, including 24-hydroxycholesterol (OHC). Supplementation of reconstituted HDL with 24-OHC enhanced and, in cells lacking ABCG1 or the 24-OHC synthesizing enzyme CYP46A1, restored the protective activity of HDL. Inhibition of SMO countered the beneficial effects of HDL and also LDL, and SMO agonists decreased β-cell apoptosis in the absence of ABCG1 or CYP46A1. The translocation of the SMO-activated transcription factor glioma-associated oncogene GLI-1 was inhibited by ER stress but restored by both HDL and 24-OHC. In conclusion, the protective effect of HDL to counter ER stress and β-cell death involves the transport, generation, and mobilization of oxysterols for activation of the Hh signaling receptor SMO

S-Palmitoylation is a reversible post-translational lipid modification that dynamically regulates protein functions. Voltage-gated sodium channels are subjected to S-palmitoylation and exhibit altered functions in different S-palmitoylation states. Our aim was to investigate whether and how S-palmitoylation regulates Nav1.6 channel function and to identify S-palmitoylation sites that can potentially be pharmacologically targeted. Acyl-biotin exchange assay showed that Nav1.6 is modified by S-palmitoylation in the mouse brain and in a Nav1.6 stable HEK 293 cell line. Using whole-cell voltage clamp, we discovered that enhancing S-palmitoylation with palmitic acid increases Nav1.6 current, whereas blocking S-palmitoylation with 2-bromopalmitate reduces Nav1.6 current and shifts the steady-state inactivation in the hyperpolarizing direction. Three S-palmitoylation sites (Cys1169, Cys1170, and Cys1978) were identified. These sites differentially modulate distinct Nav1.6 properties. Interestingly, Cys1978 is exclusive to Nav1.6 among all Nav isoforms and is evolutionally conserved in Nav1.6 among most species. Cys1978 S-palmitoylation regulates current amplitude uniquely in Nav1.6. Furthermore, we showed that eliminating S-palmitoylation at specific sites alters Nav1.6-mediated excitability in dorsal root ganglion neurons. Therefore, our study reveals S-palmitoylation as a potential isoform-specific mechanism to modulate Nav activity and neuronal excitability in physiological and diseased conditions.