Protein Apolipoprotein Research Articles

Abstract MP41: A Diet High in Carbohydrate and Low in Fat Alters the HDL Proteome and Metabolism of 9 HDL Proteins in Humans

Introduction: When dietary carbohydrate replaces fat, HDL cholesterol (HDL-C) and the primary HDL protein apolipoprotein A1 (apoA1) decrease. The proportion in plasma of large HDL2 decreases while small HDL3 increases. These findings suggest that diet affects metabolically important attributes of HDL that produce the size changes. We studied in humans the effect of dietary carbohydrate and unsaturated fat on the HDL proteome and metabolism of 9 HDL proteins across 5 HDL sizes. Methods and Results: Twelve participants were placed on a healthy, controlled diet high in unsaturated fat (HF) or high in carbohydrate (HC) in a randomized crossover design. At the end of each 4-week diet period, subjects were infused with a stable isotope tracer (D3-Leu) in order to label all newly synthesized HDL proteins. Blood samples were collected and tracer was followed for 70 hrs post-infusion. ApoA1-HDL was isolated by immunoaffinity purification, separated into 5 HDL particle sizes, and prepared for analysis by mass spectrometry. We used label free quantification to characterize the HDL proteome. The proteome composition and distribution across the 5 HDL sizes were remarkably conserved in all subjects on both diets. Diet altered the abundance of several proteins on the major HDL sizes alpha2 and alpha3. The HC diet increased proteins involved in lipid metabolism (apoC3, apoA2) and decreased antioxidant (PON1, PON3) and protease inhibitor (SERPINA3, SERPING1) proteins. We also monitored the metabolism of 9 proteins that likely affect HDL metabolism - apoA1, apoA2, apoA4, apoC3, apoE, apoJ, apoL1, apoM and LCAT. We used parallel reaction monitoring and XPI software to measure the amount of D3-Leu tracer over time in these 9 proteins across the 5 HDL sizes. We found that the HC diet increased apoA2 and apoJ and decreased apoA1 pool sizes on large HDL. The HC diet also increased apoM turnover in large HDL, and apoA1, apoA2, and apoE turnover across the HDL size range. Conclusions: Dietary carbohydrate when it replaces unsaturated fat alters the HDL proteome and metabolism of several HDL proteins on specific HDL sizes. Carbohydrate increases the abundance of proteins involved in lipid metabolism, decreases antioxidant and protease inhibitor proteins, and accelerates turnover of apoA1, apoA2, apoE, and apoM. This study suggests that diet modulates HDL function by affecting HDL composition and the metabolism of major HDL proteins.

Effects of Microglial Cytokines on Alzheimer's Disease-Related Phenomena.

Recent association studies indicate several genes highly expressed by microglia influence Alzheimer's disease (AD) risk, which suggests microglial function contributes to this disease. Here, we evaluated how one component of microglial function, cytokine release, affects AD-related phenomena. First, we used a 3-hour lipopolysaccharide (LPS) treatment to activate mouse BV2 microglial cells. Next, we removed the LPS-containing medium, added LPS-free medium, and after 6 hours collected the medium conditioned by the activated BV2 microglial cells. We then exposed human neuronal SH-SY5Y cells to the conditioned medium for 24 hours. At the end of the 24-hour exposure, we assessed amyloid-β protein precursor (AβPP), tau, apolipoprotein E (ApoE), and lipid status. The amount of AβPP was unaffected, although a slight decrease in soluble AβPPα suggested a subtle reduction in AβPP non-amyloidogenic processing occurred. Tau mRNA increased, but total and phosphorylated tau levels were unchanged. ApoE mRNA increased, while ApoE protein levels were lower. Per cell lipid droplet number decreased and lipid oxidation increased. These results show cytokine release by activated microglial cells can influence specific AD-relevant physiologies and pathologies.

3-Iodothyronamine-A Thyroid Hormone Metabolite With Distinct Target Profiles and Mode of Action.

The rediscovery of the group of thyronamines (TAMs), especially the first detailed description of their most prominent congener 3-iodothyronamine (3T1AM) 14 years ago, boosted research on this thyroid hormone metabolite tremendously. TAMs exert actions partly opposite to and distinct from known functions of thyroid hormones. These fascinating metabolic, anapyrexic, cytoprotective, and brain effects quickly evoked the hope to use hormone-derived TAMs as a therapeutic option. The G protein-coupled receptor (GPCR) TAAR1, a member of the trace amine-associated receptor (TAAR) family, was identified as the first target and effector of TAM action. The initial enthusiasm on pharmacological actions of exogenous TAMs elicited many questions, such as sites of biosynthesis, analytics, modes of action, inactivation, and role of TAMs in (patho)physiology. Meanwhile, it became clear that TAMs not only interact with TAAR1 or other TAAR family members but also with several aminergic receptors and non-GPCR targets such as transient receptor potential channels, mitochondrial proteins, and the serum TAM-binding protein apolipoprotein B100, thus classifying 3T1AM as a multitarget ligand. The physiological mode of action of TAMs is still controversial because regulation of endogenous TAM production and the sites of its biosynthesis are not fully elucidated. Methods for 3T1AM analytics need further validation, as they revealed different blood and tissue concentrations depending on detection principles used such as monoclonal antibody-based immunoassay vs liquid chromatography- matrix-assisted laser desorption/ionization mass spectrometry or time-of-flight mass spectrometry. In this review, we comprehensively summarize and critically evaluate current basic, translational, and clinical knowledge on 3T1AM and its main metabolite 3-iodothyroacetic acid, focusing on endocrine-relevant aspects and open but highly challenging issues.

A Strategy for Discovery and Verification of Candidate Biomarkers in Cerebrospinal Fluid of Preclinical Alzheimer's Disease.

Alzheimer’s disease (AD), a progressive neurodegenerative disease, is characterized by the accumulation of senile plaques, neurofibrillary tangles, and loss of synapses and neurons in the brain. The pathophysiological process of AD begins with a long asymptomatic phase, which provides a potential opportunity for early therapeutic intervention. Therefore, it is crucial to define putative biomarkers via reliable and validated methods for early diagnosis of AD. Here, we characterized candidate biomarkers by discovery proteomics analysis of cerebrospinal fluid (CSF), revealing that 732 and 704 proteins with more than one unique peptide were identified in healthy controls and preclinical AD patients, respectively. Among them, 79 and 98 proteins were significantly altered in preclinical AD for women and men, respectively, many of which have been demonstrated with consistent regulation pattern in patients with mild cognitive impairment or AD dementia. In-house developed 5-plex isotopic N,N-dimethyl leucine (iDiLeu) tags were further utilized to verify candidate biomarkers, neurosecretory protein VGF (VGF) and apolipoprotein E (apoE). By labeling peptide standards with different iDiLeu tags, a four-point internal calibration curve was constructed to allow for determination of the absolute amount of target analytes in CSF through a single liquid chromatography-mass spectrometry run.

Low-Density Lipoprotein-Reactive T Cells Regulate Plasma Cholesterol Levels and Development of Atherosclerosis in Humanized Hypercholesterolemic Mice

Atherosclerotic cardiovascular disease is a chronic inflammatory process initiated when cholesterol-carrying low-density lipoprotein (LDL) is retained in the arterial wall. CD4+ T cells, some of which recognize peptide components of LDL as antigen, are recruited to the forming lesion, resulting in T-cell activation. Although these T cells are thought to be proatherogenic, LDL immunization reduces disease in experimental animals. These seemingly contradictory findings have hampered the development of immune-based cardiovascular therapy. The present study was designed to clarify how activation of LDL-reactive T cells impacts on metabolism and vascular pathobiology. We have developed a T-cell receptor-transgenic mouse model to characterize the effects of immune reactions against LDL. Through adoptive cell transfers and cross-breeding to hypercholesterolemic mice expressing the antigenic human LDL protein apolipoprotein B-100, we evaluate the effects on atherosclerosis. A subpopulation of LDL-reactive T cells survived clonal selection in the thymus, developed into T follicular helper cells in lymphoid tissues on antigen recognition, and promoted B-cell activation. This led to production of anti-LDL immunoglobulin G antibodies that enhanced LDL clearance through immune complex formation. Furthermore, the cellular immune response to LDL was associated with increased cholesterol excretion in feces and with reduced vascular inflammation. These data show that anti-LDL immunoreactivity evokes 3 atheroprotective mechanisms: antibody-dependent LDL clearance, increased cholesterol excretion, and reduced vascular inflammation.

Blood-based redox-signature and their association to the cognitive scores in MCI and Alzheimer’s disease patients

Oxidative stress plays a pivotal and early role in the pathophysiology of Alzheimer's disease (AD). There is convincing evidence that oxidative alterations in AD and in mild cognitive impairment (MCI) patients are not limited to the brain but are extended to the blood compartment. However, the oxidative pattern in plasma is still inconclusive. Moreover, their potential association with the clinical scores MMSE (Mini-Mental State Examination) and MoCA (Montreal Cognitive Assessment) is poorly investigated. The aim of our study was to establish a pattern of blood-based redox alterations in prodromal AD and their evolution during the progression of the disease. Our results showed a reduction in the total antioxidant capacity (TAC) and an increase of the stress-response proteins apolipoprotein J (ApoJ) and Klotho in MCI subjects. For the first time, we evidenced circulating-proteasome activity. We found that the alteration of the circulating-proteasome activity is associated with the accumulation of oxidized proteins in plasma form early AD. Interestingly, the TAC, the levels of vitamin D and the activity of proteasome were positively associated to the clinical scores MMSE and MoCA. The levels of protein carbonyls and of ApoJ were negatively associated to the MMSE and MoCA scores. The levels of apolipoprotein D (ApoD) were not different between groups. Interestingly, the receiver operating characteristic (ROC) curves analysis indicated that these redox markers provide a fair classification of different groups with high accuracy. Overall, our results strengthen the notion that some specific oxidative markers could be considered as non-invasive blood-based biomarkers for an early MCI diagnosis and AD progression.

Abstract 167: Mechanism of Increased Low Density Lipoprotein Cholesterol and Decreased Triglycerides with Sodium-glucose Co-transporter 2 Inhibition

Objective: Although Sodium glucose cotransporter 2 (SGLT2) inhibition in humans sometimes leads to increased levels of low density lipoprotein (LDL) cholesterol, this therapy is associated with marked reduction in cardiovascular disease. In this study, we aimed to determine how SGLT2 inhibition alters circulating lipoproteins. Approach and Results: We used a mouse model in which plasma lipoprotein profiles were humanized by expression of human cholesteryl ester transfer protein and human apolipoprotein B100 to determine how SGLT2 inhibition alters lipoprotein profiles. The mice were fed a high fat diet and then were made partially insulin deficient using streptozotocin. SGLT2 was inhibited using a specific anti-sense oligonucleotide or canagliflozin, a clinically available oral SGLT2 inhibitor. Inhibition of SGLT2 increased circulating levels of LDL cholesterol and reduced plasma triglyceride levels. SGLT2 inhibition was associated with increased lipoprotein lipase activity in the post heparin plasma and decreased postprandial lipemia. The changes in lipoprotein metabolism were more significant in mice treated with SGLT2 ASO compared to canagliflozin. Conclusions: Our studies in mice recapitulate many of the changes in circulating lipids found with SGLT2 inhibition therapy in humans and suggest that the increased LDL cholesterol found with this therapy is due to greater lipolysis of triglyceride-rich lipoproteins. This change in lipoprotein physiology is likely, in part, to explain the reduced cardiovascular disease found with SGLT2 inhibition.

Abstract 392: Nanoparticle-based Biosensors for Measuring Apolipoprotein A-I and HDL Function

Background: High-density lipoproteins (HDL) are dynamic circulating nanoparticles that carry cholesterol and have numerous functions. Rapid measurement of HDL, the HDL-associated protein apolipoprotein A-I (apoAI), or HDL function(s) is not currently possible. Such technology may provide new opportunities for HDL monitoring. We utilized nanoparticles to develop a method of sequestering apoAI from solution, including human serum, and for measuring the activity of the HDL-maturing and apoAI-dependent enzyme, lecithin:cholesterol acyl transferase (LCAT). Methods: Gold nanoparticles were surface-functionalized with phospholipids. The synthesized particles were incubated with various amounts of apoAI or with purchased, LDL-depleted, human serum samples where the apoAI amount was measured using an ELISA. After incubation, the particles were easily isolated and apoAI sequestration by the nanoparticles was measured using ELISA. As apoAI is a cofactor that activates LCAT, nanoparticles were incubated with various amounts of apoA1, LCAT, and free cholesterol or with the LDL-depleted human serum samples (diluted) for 1 hour at 37°C to enable binding of apoAI, cholesterol, and LCAT activity. The nanoparticles were easily isolated and the particle-associated cholesteryl ester was measured using an Amplex Red Cholesterol Assay kit. Results: The nanoparticles sequester apoAI according to the concentration of apoAI in solution (R = 0.668, p = 0.035, N = 10). Also, data reveal that the LCAT binds the nanoparticle-apoAI structures and catalyzes the conversion of cholesterol to cholesteryl ester. The amount of cholesteryl ester bound to the nanoparticles is directly dependent on the amount of apoAI (R = 0.729, p = 0.016, N=10). Conclusion: These results demonstrate that specific, functionalized nanoparticles can be added to serum to sequester apoAI in dose-response. Also, the formed conjugate structures activate LCAT whereby the amount of cholesteryl ester formed on the nanoparticle directly correlates with apoAI. Overall, this technology provides a framework and new approach for developing next generation HDL- and HDL-function specific biosensors.

Temporary sequestration of cholesterol and phosphatidylcholine within extracellular domains of ABCA1 during nascent HDL generation

The quality and quantity of high-density lipoprotein (HDL) in blood plasma are important for preventing coronary artery disease. ATP-binding cassette protein A1 (ABCA1) and apolipoprotein A-I (apoA-I) play essential roles in nascent HDL formation, but controversy persists regarding the mechanism by which nascent HDL is generated. In the “direct loading model”, apoA-I acquires lipids directly from ABCA1 while it is bound to the transporter. By contrast, in the “indirect model”, apoA-I acquires lipids from the specific membrane domains created by ABCA1. In this study, we found that trypsin treatment causes rapid release of phosphatidylcholine (PC) and cholesterol from BHK/ABCA1 cells, and that the time course of lipid release coincides with those of trypsin digestion of extracellular domains (ECDs) of surface ABCA1 and of release of ECD fragments into the medium. This trypsin-dependent lipid release was dependent on ABCA1 ATPase activity, and did not occur in cells that express ABCG1, which exports lipids like ABCA1 but does not have large ECDs. These results suggest that the trypsin-sensitive sites on the cell surface are the large ECDs of ABCA1, and that lipids transported by ABCA1 are temporarily sequestered within the ECDs during nascent HDL formation.

Thyroid Hormones and Derivatives: Endogenous Thyroid Hormones and Their Targets.

More than a century after the discovery of L-Thyroxine, the main thyroid hormone secreted solely by the thyroid gland, several metabolites of this iodinated, tyrosine-derived ancestral hormone have been identified. These are utilized as hormones during development, differentiation, metamorphosis, and regulation of most biochemical reactions in vertebrates and their precursor species. Among those metabolites are the thyromimetically active 3,3',5-Triiodo-L-thyronine (T3) and 3,5-Diiodo-L-thronine, reverse-T3 (3,3',5'-Triiodo-L-thyronine) with still unclear function, the recently re-discovered thyronamines (e.g., 3-Iodo-thyronamine), which exert in part T3-antagonistic functions, the thyroacetic acids (e.g., Tetrac and Triac), as well as various sulfated or glucuronidated metabolites of this panel of iodinated signaling compounds. In the blood most of these hydrophobic metabolites are tightly bound to the serum distributor proteins thyroxine binding globulin (TBG), transthyretin (TTR), albumin or apolipoprotein B100. Cellular import and export of these charged, highly hydrophobic amino acid derivatives requires a number of cell-membrane transporters or facilitators such as MCT8 or MCT10 and members of the OATP and LAT families of transporters. Depending on their structure, the thyroid hormone metabolites exert their cellular action by binding and thus modulating the function of various receptors systems (e.g., ανβ3 integrin receptor and transient receptor potential channels (TRPM8) of the cell membrane), in part linked to intracellular downstream kinase signaling cascades, and several isoforms of membrane-associated, mitochondrial or nuclear thyroid hormone receptors (TR), which are members of the c-erbA family of ligand-modulated transcription factors. Intracellular deiodinase selenoenzymes, which obligatory are membrane integrated enzymes, ornithine decarboxylase and monoamine oxidases control local availability of biologically active thyroid hormone metabolites. Inactivation of thyroid hormone metabolites occurs mainly by deiodination, sulfation or glucuronidation, reactions which favor their renal or fecal elimination.

APOLs with low pH dependence can kill all African trypanosomes.

The primate-specific serum protein apolipoprotein L1 (APOL1) is the only secreted member of a family of cell death promoting proteins1–4. APOL1 kills the bloodstream parasite Trypanosoma brucei brucei, but not the human sleeping sickness agents T.b. rhodesiense and T.b. gambiense3. We considered the possibility that intracellular members of the APOL1 family, against which extracellular trypanosomes could not have evolved resistance, could kill pathogenic T. brucei subspecies. Here we show that recombinant APOL3 (rAPOL3) kills all African trypanosomes including T.b. rhodesiense, T.b. gambiense and the animal pathogens T. evansi, T. congolense and T. vivax. In contrast, rAPOL3 did not kill more distant trypanosomes such as T. theileri or T. cruzi. This trypanolytic potential was partially shared by rAPOL1 from Papio papio (rPpAPOL1). The differential killing ability between rAPOL3 and rAPOL1 was associated with distinct dependence on acidic pH for activity. Due to both instability and toxicity when injected into mice rAPOL3 cannot be used for treatment of infection, but an experimental rPpAPOL1 mutant inspired by APOL3 exhibited enhanced trypanolytic activity in vitro and ability to completely inhibit T.b. gambiense infection in mice. We conclude that pH dependence influences the trypanolytic potential of rAPOLs.

Transcriptional Effects of ApoE4: Relevance to Alzheimer's Disease.

The major genetic risk factor for sporadic Alzheimer's disease (AD) is the lipid binding and transporting carrier protein apolipoprotein E, epsilon 4 allele (ApoE4). One of the unsolved mysteries of AD is how the presence of ApoE4 elicits this age-associated, currently incurable neurodegenerative disease. Recently, we showed that ApoE4 acts as a transcription factor and binds to the promoters of genes involved in a range of processes linked to aging and AD disease pathogenesis. These findings point to novel therapeutic strategies for AD and aging, resulting in an extension of human healthspan, the disease-free and functional period of life. Here, we review the effects and implications of the putative transcriptional role of ApoE4 and propose a model of Alzheimer's disease that focuses on the transcriptional nature of ApoE4 and its downstream effects, with the aim that this knowledge will help to define the role ApoE4 plays as a risk factor for AD, aging, and other processes such as inflammation and cardiovascular disease.

Reduction of cardiovascular risk in subjects with high lipoprotein (a) levels

Lipoprotein (a) (Lp (a)) is a plasma lipoprotein consisting of a cholesterol rich LDL particle with one molecule of apolipoprotein B100 and one protein apolipoprotein (a) [apo(a)].

Advances in the management of dyslipidemia.

Cardiovascular disease is the leading cause of morbidity and mortality in the United States and therapies aimed at lipid modification are important for the reduction of cardiovascular risk. There have been many exciting advances in lipid management over the recent years. This review discusses these recent advances as well as the direction of future studies. Several recent clinical trials support low-density lipoprotein cholesterol (LDL-c) reduction beyond maximal statin therapy for improved cardiovascular outcomes. Ezetimibe reduced LDL-c beyond maximal statin therapy and was associated with improved cardiovascular outcomes for high-risk populations. Further LDL-c reduction may also be achieved with proprotein convertase subtilisin/kexin type-9 (PCSK9) inhibition and a recent trial, Further Cardiovascular Outcomes Research with PCSK9 Inhibition in Subjects with Elevated Risk (FOURIER), was the first to show reduction in cardiovascular events for evolocumab. Additional outcome studies of monoclonal antibody and RNA-targeted PCSK9 inhibitors are underway. Quantitative high-density lipoprotein cholesterol (HDL-c) improvements have failed to have clinical impact to date; most recently, cholesteryl ester transfer protein inhibitors and apolipoprotein infusions have demonstrated disappointing results. There are still ongoing trials in both of these areas, but some newer therapies are focusing on HDL functionality and not just the absolute HDL-c levels. There are several ongoing studies in triglyceride reduction including fatty acid therapy, inhibition of apolipoprotein C-3 or ANGTPL3 and peroxisome proliferator-activated receptor-α agonists. Lipid management continues to evolve and these advances have the potential to change clinical practice in the coming years.

27-Hydroxycholesterol regulates cholesterol synthesis and transport in C6 glioma cells

The oxysterol 27-Hydroxycholesterol (27-OHC) is a major cholesterol metabolite that can cross the blood brain barrier (BBB) from peripheral circulation to the brain. Currently, the role of 27-OHC on cholesterol homeostasis in astrocytes and the underlying mechanisms are not defined. Since all brain cholesterol is essentially synthesized in brain itself and astrocytes as net producers of cholesterol are essential for normal brain function, here we investigated the effects of 27-OHC on cholesterol synthesis and transport in C6 glioma cells. C6 cells were treated with 5, 10 and 20μM 27-OHC for 24h and the cell viability and apoptosis, the cholesterol levels and metabolism-related mediators, genes and proteins were subsequently assessed using cell-counting kit (CCK)-8, Amplex red, ELISA, real-time PCR and Western blot, respectively. We found that 27-OHC decreased cholesterol levels by down-regulating the expression of sterol-regulated element binding protein-1 (SREBP-1a), 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CR) and low density lipoprotein receptor (LDLR) and promoted cholesterol transport by up-regulating the expression of peroxisome proliferator-activated receptors-γ (PPAR-γ), liver X receptor-α (LXR-α), ATP-binding cassette transporter protein family member A1 (ABCA1) and apolipoprotein E (ApoE)genes. Our results suggested that 27-OHC may represent a sensitive modulator of cholesterol metabolism disorder by suppressing cholesterol synthesis and stimulating cholesterol transport in astrocytes.

Biochemical and proteomic analyses of the physiological response induced by individual housing in gilts provide new potential stress markers.

BackgroundThe objective assessment of animal stress and welfare requires proper laboratory biomarkers. In this work, we have analyzed the changes in serum composition in gilts after switching their housing, from pen to individual stalls, which is generally accepted to cause animal discomfort.ResultsBlood and saliva samples were collected a day before and up to four days after changing the housing system. Biochemical analyses showed adaptive changes in lipid and protein metabolism after the housing switch, whereas cortisol and muscular markers showed a large variability between animals. 2D-DIGE and iTRAQ proteomic approaches revealed variations in serum protein composition after changing housing and diet of gilts. Both techniques showed alterations in two main homeostatic mechanisms: the innate immune and redox systems. The acute phase proteins haptoglobin, apolipoprotein A-I and α1-antichymotrypsin 3, and the antioxidant enzyme peroxiredoxin 2 were found differentially expressed by 2D-DIGE. Other proteins related to the innate immune system, including lactotransferrin, protegrin 3 and galectin 1 were also identified by iTRAQ, as well as oxidative stress enzymes such as peroxiredoxin 2 and glutathione peroxidase 3. Proteomics also revealed the decrease of apolipoproteins, and the presence of intracellular proteins in serum, which may indicate physical injury to tissues.ConclusionsHousing of gilts in individual stalls and diet change increase lipid and protein catabolism, oxidative stress, activate the innate immune system and cause a certain degree of tissue damage. We propose that valuable assays for stress assessment in gilts may be based on a score composed by a combination of salivary cortisol, lipid metabolites, innate immunity and oxidative stress markers and intracellular proteins.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-016-0887-1) contains supplementary material, which is available to authorized users.

Comparative proteome analysis of egg yolk plasma proteins during storage

Physical changes such as chicken egg white thinning and egg yolk flattening occur during storage, implying a decline in egg quality. To reveal the deteriorative process related to chicken egg internal quality, a comparative proteomic method was used in this study to analyze the alterations in egg yolk plasma proteins at different storage times (0, 20 and 40 days) under an ambient temperature of 22 ± 2 °C. Using two-dimensional electrophoresis followed by matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry, 33 protein spots representing 12 proteins were identified with significant (P < 0.05) alterations in abundance at different storage times. The proteins that showed significant changes in abundance included serum albumin, vitellogenin fragments, IgY chains, ovalbumin, ovoinhibitor, α2 -macroglobulin-like protein 1-like, hemopexin, transthyretin, apolipoprotein A-I and β2 -glycoprotein I precursor. Accelerating degradation for most egg yolk plasma proteins was observed after prolonged storage (from day 20 to day 40). It is likely that the increased degradation of protease inhibitors such as ovoinhibitor and α2 -macroglobulin-like protein 1-like during prolonged storage lead to an imbalance of protease and antiprotease in egg yolk, which may play a key role in the degradation of egg yolk proteins. These findings will provide an insight into the effects of storage on egg yolk protein changes and give a deeper understanding of the deteriorative process of chicken egg yolk. © 2016 Society of Chemical Industry.

Apolipoprotein E as a Therapeutic Target in Alzheimer's Disease: A Review of Basic Research and Clinical Evidence.

Alzheimer's disease (AD) is a devastating neurodegenerative disorder that causes progressive cognitive decline. The majority of AD cases are sporadic and late-onset (>65years old) making it the leading cause of dementia in the elderly. While both genetic and environmental factors contribute to the development of late-onset AD (LOAD), APOE polymorphism is a major genetic risk determinant for LOAD. In humans, the APOE gene has three major allelic variants: ε2, ε3, and ε4, of which APOE ε4 is the strongest genetic risk factor for LOAD, whereas APOE ε2 is protective. Mounting evidence suggests that APOE ε4 contributes to AD pathogenesis through multiple pathways including facilitated amyloid-β deposition, increased tangle formation, synaptic dysfunction, exacerbated neuroinflammation, and cerebrovascular defects. Since APOE modulates multiple biological processes through its corresponding protein apolipoprotein E (apoE), APOE gene and apoE properties have been a promising target for therapy and drug development against AD. In this review, we summarize the current evidence regarding how the APOE ε4 allele contributes to the pathogenesis of AD and how relevant therapeutic approaches can be developed to target apoE-mediated pathways in AD.

Lower functional connectivity of default mode network in cognitively normal young adults with mutation of APP, presenilins and APOE ε4.

In this study, we used resting-state functional magnetic resonance imaging to explore the genetic effects of amyloid precursor protein (APP) or presenilins mutation and apolipoprotein E (APOE) ε4 on the default-mode network (DMN) in cognitively intact young adults (24.1±2.5years). Both the APP or presenilin-1/2 group and the APOE ε4 group had significantly lower DMN functional connectivity (FC) in the some brain regions like precuneus/middle cingulate cortices (PCu/MCC) than controls (AlphaSim corrected, P<0.05). Only a lower FC tendency was demonstrated (control<APOE ε4<APP or presenilin-1/2 group). Moreover, lower FC in PCu/MCC is correlated with some neuropsychological assessments such as similarity test in APOE ε4 group. These findings indicate that DMN FC alteration in APP or presenilin-1/2 or APOE ε4 subjects is prior to the occurrence of neurological alterations and clinical symptoms, and DMN FC might be a valuable biomarker to detect genetic risk in the preclinical stage.

Apolipoprotein A-I Mimetic Peptide D-4F Reduces Cardiac Hypertrophy and Improves Apolipoprotein A-I-Mediated Reverse Cholesterol Transport From Cardiac Tissue in LDL Receptor-null Mice Fed a Western Diet.

Epidemiological studies have suggested that hypercholesterolemia is an independent determinant of increased left ventricular (LV) mass. Because high-density lipoprotein and its major protein apolipoprotein A-I (apoA-I) mediate reverse cholesterol transport (RCT) and have cardiac protective effects, we hypothesized that the apoA-I mimetic peptide D-4F could promote RCT in cardiac tissue and decrease cardiac hypertrophy induced by hypercholesterolemia. Low-density lipoprotein receptor-null mice were fed by a Western diet for 18 weeks and then randomized to receive water, or D-4F 0.3 mg/mL, or D-4F 0.5 mg/mL added to drinking water for 6 weeks. After D-4F administration, an increase in high-density lipoprotein cholesterol and a decrease in low-density lipoprotein cholesterol, total cholesterol, and triglyceride in a trend toward dose-responsivity were found in cardiac tissue. Ultrasound biomicroscopy revealed a reduction in LV posterior wall end-diastolic dimension, and an increase in mitral valve E/A ratio and LV ejection fraction. Hematoxylin-eosin staining showed reduced LV wall thickness and myocardial cell diameter. The protein levels of ABCA1 and LXRα were elevated in cardiac tissue of D-4F treated mice compared with the controls (P < 0.05). These results demonstrated that D-4F treatment reduced cardiac hypertrophy, and improved cardiac performance in low-density lipoprotein receptor-null mice fed a Western diet, presumably through the LXRα-ABCA1 pathway associated with enhanced myocardial RCT.