Proteomic analysis of the very low density lipoprotein (VLDL) transport vesicles

The VLDL transport vesicle (VTV) mediates the transport of nascent VLDL particles from the ER to the Golgi and plays a key role in VLDL-secretion from the liver. The functionality of VTV is controlled by specific proteins; however, full characterization and proteomic profiling of VTV remain to be carried out. Here, we report the first proteomic profile of VTVs. VTVs were purified to their homogeneity and characterized biochemically and morphologically. Thin section transmission electron microscopy suggests that the size of VTV ranges between 100 nm to 120 nm and each vesicle contains only one VLDL particle. Immunoblotting data indicate VTV concentrate apoB100, apoB48 and apoAIV but exclude apoAI. Proteomic analysis based on 2D-gel coupled with MALDI-TOF identified a number of vesicle-related proteins, however, many important VTV proteins could only be identified using LC-MS/MS methodology. Our data strongly indicate that VTVs greatly differ in their proteome with their counterparts of intestinal origin, the PCTVs. For example, VTV contains Sec22b, SVIP, ApoC-I, reticulon 3, cideB, LPCAT3 etc. which are not present in PCTV. The VTV proteome reported here will provide a basic tool to study the mechanisms underlying VLDL biogenesis, maturation, intracellular trafficking and secretion from the liver.     

High-valent tin(IV) porphyrin: An efficient and reusable catalyst for tetrahydropyranylation of alcohols and phenols under mild conditions

In this paper, rapid and highly efficient tetrahydropyranylation of alcohols and phenols with 3,4-dihydro-2H-pyran (DHP) in the presence of catalytic amounts of high-valent tin (IV) tetraphenylporphyrinato trifluoromethanesufonate, [Sn^IV(TPP)(OTf)₂] is reported. In this catalytic system, primary, secondary and tertiary alcohols as well as phenols were converted to their corresponding tetrahydropyranyl ethers (THP-ethers) in excellent yields and short reaction times at room temperature. It is noteworthy that this method can be used for chemoselective tetrahydropyranylation of primary alcohols in the presence of secondary and tertiary alcohols and phenols. The catalyst was reused several times in the protection reactions without loss of its catalytic activity.     

Bag culture: a method for root-root co-culture

A method named "bag culture" was developed for coculturing of Linum persicum (section Syllinum) and L. austriacum (section Linum) hairy roots. For this propose L. austriacum and L. persicum hairy root cultures were established using Agrobacterium rhizogenes in McCown medium. L. persicum hairy roots in bags (1 mm2 mesh) were successfully grown together with L. austriacum hairy roots. The amounts of podophyllotoxin (PTOX) and 6-methoxypodophyllotoxin (MPTOX) produced by L. persicum hairy root cultures were detected using HPLC. The results indicated that the amounts of both lignans and growth indexes of the two hairy roots decreased, that may be partly due to a competition between the two types of culture in using precursors of biosynthetic metabolites and the amount of culture medium which is available for each hairy root. However, MPTOX (0.17 g/100 g DW) and PTOX (0.02 g/100 g DW) levels of the L. persicum single culture in bag were significantly higher than of the other cultures which may be due to the immobilization effect of the bag.     

The identification of a novel endoplasmic reticulum to Golgi SNARE complex used by the prechylomicron transport vesicle

Dietary long chain fatty acids are absorbed in the intestine, esterified to triacylglycerol, and packaged in the unique lipoprotein of the intestine, the chylomicron. The rate-limiting step in the transit of chylomicrons through the enterocyte is the exit of chylomicrons from the endoplasmic reticulum in prechylomicron transport vesicles (PCTV) that transport chylomicrons to the cis-Golgi. Because chylomicrons are 250 nm in average diameter and lipid absorption is intermittent, we postulated that a unique SNARE pairing would be utilized to fuse PCTV with their target membrane, cis-Golgi. PCTV loaded with [(3)H]triacylglycerol were incubated with cis-Golgi and were separated from the Golgi by a sucrose step gradient. PCTV-chylomicrons acquire apolipoprotein-AI (apoAI) only after fusion with the Golgi. PCTV became isodense with Golgi upon incubation and were considered fused when their cargo chylomicrons acquired apoAI but docked when they did not. PCTV, docked with cis-Golgi, were solubilized in 2% Triton X-100, and proteins were immunoprecipitated using VAMP7 or rBet1 antibodies. In both cases, a 112-kDa complex was identified in nonboiled samples that dissociated upon boiling. The constituents of the complex were VAMP7, syntaxin 5, vti1a, and rBet1. Antibodies to each SNARE component significantly inhibited fusion of PCTV with cis-Golgi. Membrin, Sec22b, and Ykt6 were not found in the 112-kDa complex. We conclude that the PCTV-cis-Golgi SNARE complex is composed of VAMP7, syntaxin 5, Bet1, and vti1a.     

Antidiabetic Medications for Type 2 Diabetics with Nonalcoholic Fatty Liver Disease: Evidence From a Network Meta-Analysis of Randomized Controlled Trials

ObjectiveType 2 diabetes mellitus and nonalcoholic fatty liver disease (NAFLD) are closely related, and antidiabetic medications have been shown to be potential therapeutics in NAFLD. Using a network meta-analysis, we sought to examine the effectiveness of antidiabetic agents for the treatment of NAFLD in patients with type 2 diabetes mellitus.MethodsMedline and Embase were searched for randomized controlled trials relating to the use of antidiabetic agents, including sodium-glucose transport protein 2 (SGLT2) inhibitors, glucagon-like peptide-1 receptor agonists, and peroxisome proliferator-activated receptor gamma (PPARγ) agonists, biguanides, sulfonylureas and insulin, on NAFLD in patients with diabetes. The p-score was used as a surrogate marker of effectiveness.ResultsA total of 14 articles were included in the analysis. PPARγ agonists were ranked as the best treatment in steatosis reduction, resulting in the greatest reduction of steatosis. There was statistical significance between PPARγ agonists [mean difference (MD): ?6.02%, confidence interval (CI): ?10.37% to ?1.67%] and SGLT2 inhibitors (MD: ?2.60%, CI: ?4.87% to ?0.33%) compared with standard of care for steatosis reduction. Compared with PPARγ agonists, SGLT2 inhibitors resulted in a statistical significant reduction in fibrosis (MD: ?0.06, CI: ?0.10 to ?0.02). Body mass index reduction was highest in SGLT2 inhibitors and glucagon-like peptide-1 receptor agonists. Additionally, SGLT2 inhibitors were ranked as the best treatment for increasing high-density lipoprotein and reducing low-density lipoprotein.ConclusionGlucagon-like peptide-1 receptor agonists and SGLT2 inhibitors were suitable alternatives for the treatment of NAFLD in those with type 2 diabetes mellitus with a reduction in body mass index, fibrosis, and steatosis. SGLT2 inhibitors also have the added benefit of lipid modulation.     

Metabolic Associated Fatty Liver Disease Increases the Risk of Systemic Complications and Mortality. A Meta-Analysis and Systematic Review of 12 620 736 Individuals

ObjectiveThe recent introduction of the term metabolic associated fatty liver disease (MAFLD) sought to reclassify nonalcoholic fatty liver disease (NAFLD). MAFLD is thought to improve the encapsulation of metabolic dysregulation. However, recent evidence has found significant differences between MAFLD and NAFLD, and prevailing knowledge has largely arisen from studies on NAFLD. Hence, we conducted a meta-analysis and systematic review of the outcomes associated with MAFLD.MethodsMEDLINE and Embase databases were searched for articles relating to outcomes in MAFLD. Analysis was conducted in random effects with hazard ratios (HRs) to account for longitudinal risk assessment of mortality and systemic complications.ResultsA total of 554 articles were identified, of which 17 articles were included. MAFLD resulted in an increase in the overall mortality (HR, 1.24; confidence interval [CI], 1.13-1.34), cancer-related mortality (HR, 1.27; CI, 1.01-1.54), and cardiovascular disease mortality (HR, 1.28, 1.03-1.53; P = .04) compared with non-MAFLD. MAFLD also increases the risk of cardiovascular events (HR, 1.49; CI, 1.34-1.64; P < .01), stroke (HR, 1.55; CI, 1.37-1.73; P < .01), and chronic kidney disease (HR, 1.53; CI, 1.38-1.68). The presence of MAFLD was also associated with an increased risk of heart failure, obstructive sleep apnea, and malignancy.ConclusionMAFLD can significantly elevate the risk of systemic diseases and mortality. The care of MAFLD thus requires interdisciplinary collaboration, and future clinical trials conducted on MAFLD should aim to reduce the incidence of end-organ damage aside from improving liver histology.