👤 Hanyu Weng

Cholecystokinin (CCK) and apolipoprotein A-IV (ApoA-IV) are gastrointestinal peptides that play an important role in controlling energy homeostasis. Lymphatic ApoA-IV and plasma CCK secretion are mediated via a chylomicron formation-dependent pathway during a dietary lipid infusion. Given their similar roles as satiating proteins, the present study examines how the two peptides interact in their function. Specifically, this study sought to understand how ApoA-IV regulates CCK secretion. For this purpose, Cck gene expression in the small intestines of ApoA-IV knockout (ApoA-IV-KO) and wild-type (WT) mice were compared under an array of feeding conditions. When fed with a chow or high-fat diet (HFD), basal levels of Cck transcripts were significantly reduced in the duodenum of ApoA-IV-KO mice compared to WT mice. Furthermore, after an oral gavage of a lipid mixture, Cck gene expression in the duodenum was significantly reduced in ApoA-IV-KO mice relative to the change seen in WT mice. To determine the mechanism by which ApoA-IV modulates Cck gene expression, STC-1 cells were transfected with predesigned mouse lysophosphatidic acid receptor 5 (LPAR5) small interfering RNA (siRNA) to knockdown Lpar5 gene expression. In this in-vitro study, mouse recombinant ApoA-IV protein increased Cck gene expression in enteroendocrine STC-1 cells and stimulated CCK release from the STC-1 cells. However, the levels of CCK protein and Cck expression were attenuated when Lpar5 was knocked down in the STC-1 cells. Together these observations suggest that dietary lipid-induced ApoA-IV is associated with Cck synthesis in the duodenum and that ApoA-IV protein directly enhances CCK release through the activation of a LPAR5-dependent pathway. Show less

Data from epidemiological studies and clinical trials suggest an influence of dietary and circulating polyunsaturated fatty acids (PUFAs) on the hemostasis profile. Genome-wide association studies (GWAS) have identified single nucleotide polymorphisms (SNPs) related to plasma PUFAs levels. We aimed to investigate whether the SNPs related to plasma PUFAs levels were also associated with plasma levels of hemostatic variables. We tested the associations between 9 PUFA-related SNPs and 6 hemostatic variables in 9035 European Americans (EAs) and 2702 African Americans (AAs) in the Atherosclerosis Risk in Communities (ARIC) Study. We then conducted a replication study by looking-up our novel observed associations in three published GWAS for hemostatic factors in different EA populations. We observed a novel linoleic acid-related locus at the JMJD1C region associated with factor VII activity (FVIIc): rs10740118 and rs1935, Beta (p) = -1.31 (1 × 10 Our study identified a novel association for FVIIc at JMJD1C, a histone demethylase that plays a role in DNA repair and possibly transcription regulation and RNA processing. Show less

Previous genomic studies revealed phosphotidylinositol-3-kinase (PI3K)/Akt pathway mutation in human salivary gland adenoid cystic carcinoma (ACC). No validation of its prognostic value has been reported. P-Akt, pan-Akt, phosphorylated-mammalian target of rapamycin (p-mTOR), PI3K, and insulin-like growth factor-1 receptor beta (IGF-1Rβ) were detected on 120 salivary gland ACC/adjacent salivary gland pairs immunohistochemically and were correlated with clinicopathological data. Expression of cytoplasmic and nuclear p-Akt, cytoplasmic p-mTOR, nuclear pan-Akt, and nuclear IGF-1Rβ were higher in ACC than in adjacent salivary glands. P-Akt, p-mTOR, PI3K, and IGF-1Rβ expression were correlated with one another in both cytoplasm and nucleus. Low p-mTOR expression in both subcellular compartments was associated with locoregional recurrence, poor disease-free survival (DFS), and overall survival (OS). Low nuclear p-Akt (Ser473) and p-mTOR expression were independent predictors for poor OS and DFS, respectively. High level of Akt/mTOR activation in ACC is correlated with a significantly improved survival. P-mTOR and nuclear p-Akt are prognostic biomarkers of salivary gland ACC. © 2017 Wiley Periodicals, Inc. Head Neck 39: 1145-1154, 2017. Show less

Apolipoprotein AIV (ApoAIV) and cholecystokinin (CCK) are well-known satiating signals that are stimulated by fat consumption. Peripheral ApoAIV and CCK interact to prolong satiating signals. In the present study, we hypothesized that ApoAIV and CCK control energy homeostasis in response to high-fat diet feeding. To test this hypothesis, energy homeostasis in ApoAIV and CCK double knockout (ApoAIV/CCK-KO), ApoAIV knockout (ApoAIV-KO), and CCK knockout (CCK-KO) mice were monitored. When animals were maintained on a low-fat diet, ApoAIV/CCK-KO, ApoAIV-KO, and CCK-KO mice had comparable energy intake and expenditure, body weight, fat mass, fat absorption, and plasma parameters relative to the controls. In contrast, these KO mice exhibited impaired lipid transport to epididymal fat pads in response to intraduodenal infusion of dietary lipids. Furthermore, ApoAIV-KO mice had upregulated levels of CCK receptor 2 (CCK2R) in the small intestine while ApoAIV/CCK-KO mice had upregulated levels of CCK2R in the brown adipose tissue. After 20 wk of a high-fat diet, ApoAIV-KO and CCK-KO mice had comparable body weight and fat mass, as well as lower energy expenditure at some time points. However, ApoAIV/CCK-KO mice exhibited reduced body weight and adiposity relative to wild-type mice, despite having normal food intake. Furthermore, ApoAIV/CCK-KO mice displayed normal fat absorption and locomotor activity, as well as enhanced energy expenditure. These observations suggest that mice lacking ApoAIV and CCK have reduced body weight and adiposity, possibly due to impaired lipid transport and elevated energy expenditure. Show less

Insulin can stimulate hepatic expression of carbohydrate-responsive element-binding protein (ChREBP). As recent studies revealed potential metabolic beneficial effects of ChREBP, we asked whether its expression can also be regulated by the dietary polyphenol curcumin. We also aimed to determine mechanisms underlying ChREBP stimulation by insulin and curcumin. The effect of insulin on ChREBP expression was assessed in mouse hepatocytes, while the effect of curcumin was assessed in mouse hepatocytes and with curcumin gavage in mice. Chemical inhibitors for insulin signaling molecules were utilized to identify involved signaling molecules, and the involvement of p21-activated protein kinase 1 (Pak1) was determined with its chemical inhibitor and Pak1-/- hepatocytes. We found that both insulin and curcumin-stimulated ChREBP expression in Akt-independent but MEK/ERK-dependent manner, involving the inactivation of the transcriptional repressor Oct-1. Aged Pak1-/- mice showed reduced body fat volume. Pak1 inhibition or its genetic deletion attenuated the stimulatory effect of insulin or curcumin on ChREBP expression. Our study hence suggests the existence of a novel signaling cascade Pak1/MEK/ERK/Oct-1 for both insulin and curcumin in exerting their glucose-lowering effect via promoting hepatic ChREBP production, supports the recognition of beneficial functions of ChREBP, and brings us a new overview on dietary polyphenols. Show less

Obesity is a well-known risk factor for type 2 diabetes. Genome-wide association studies have identified a number of genetic loci associated with obesity. The aim of this study is to examine the contribution of obesity-related genomic loci to type 2 diabetes in a Chinese population. We successfully genotyped 18 obesity-related single nucleotide polymorphisms among 5338 type 2 diabetic patients and 4663 controls. Both individual and joint effects of these single nucleotide polymorphisms on type 2 diabetes and quantitative glycemic traits (assessing β-cell function and insulin resistance) were analyzed using logistic and linear regression models, respectively. Two single nucleotide polymorphisms near MC4R and GNPDA2 genes were significantly associated with type 2 diabetes before adjusting for body mass index and waist circumference (OR (95% CI) = 1.14 (1.06, 1.22) for the A allele of rs12970134, P = 4.75×10(-4); OR (95% CI) = 1.10 (1.03, 1.17) for the G allele of rs10938397, P = 4.54×10(-3)). When body mass index and waist circumference were further adjusted, the association of MC4R with type 2 diabetes remained significant (P = 1.81×10(-2)) and that of GNPDA2 was attenuated (P = 1.26×10(-1)), suggesting the effect of the locus including GNPDA2 on type 2 diabetes may be mediated through obesity. Single nucleotide polymorphism rs2260000 within BAT2 was significantly associated with type 2 diabetes after adjusting for body mass index and waist circumference (P = 1.04×10(-2)). In addition, four single nucleotide polymorphisms (near or within SEC16B, BDNF, MAF and PRL genes) showed significant associations with quantitative glycemic traits in controls even after adjusting for body mass index and waist circumference (all P values<0.05). This study indicates that obesity-related genomic loci were associated with type 2 diabetes and glycemic traits in the Han Chinese population. Show less

Glycosylation is one of the most important post-translational modifications to mammalian proteins. Distribution of different glycoisoforms of certain proteins may reflect disease conditions and, therefore, can potentially be utilized as biomarkers. Apolipoprotein C3 (ApoC3) is one of the many plasma glycoproteins extensively studied for association with disease states. ApoC3 exists in three main glycoisoforms, including ApoC3-1 and ApoC3-2, which contain an O-linked carbohydrate moiety consisting of three and four monosaccharide residues, respectively, and ApoC3-0 that lacks the entire glycosylation chain. Changes in the ratio of different glycoisoforms of ApoC3 have been observed in pathological conditions such as kidney disease, liver disease, and diabetes. They may provide important information for diagnosis, prognosis, and evaluation of therapeutic response for metabolic conditions. In this current work, a liquid chromatography (LC)-high-resolution (HR) time-of-flight (TOF) mass spectrometry (MS) method was developed for relative quantitation of different glycoisoforms of intact ApoC3 in human plasma. The samples were processed using a solid-phase extraction (SPE) method and then subjected to LC-full scan HRMS analysis. Isotope peaks for each targeted glycoisoform at two charge states were extracted using a window of 50 mDa and integrated into a chromatographic peak. The peak area ratios of ApoC3-1/ApoC3-0 and ApoC3-2/ApoC3-0 were calculated and evaluated for assay performance. The results indicated that the ratio can be determined with excellent reproducibility in multiple subjects. It has also been observed that the ratios remained constant in plasma exposed to room temperature, freeze-thaw cycles, and long-term frozen storage. The method was applied in preliminary biomarker research of diabetes by analyzing plasma samples collected from normal, prediabetic, and diabetic subjects. Significant differences were revealed in the ApoC3-1/ApoC3-0 ratio and in the ApoC3-2/ApoC3-0 ratio among the three groups. The workflow of intact protein analysis using full scan HRMS established in this current work can be potentially extended to relative quantitation of other glycosylated proteins. To our best knowledge, this is the first time that a systematic approach of relative quantitation of targeted intact protein glycoisoforms using LC-MS has been established and utilized in biomarker research. Show less

Mouse embryonic fibroblasts (MEFs) differentiate into fully functional chondrocytes in response to bone morphogenetic protein-2 (BMP-2). However, the comprehensive proteomic aspect of BMP-2-induced chondrogenesis remains unknown. We took advantage of quantitative proteomic analysis based on isobaric tag for relative and absolute quantitation (iTRAQ) and on-line 2D nano-liquid chromatography/tandem mass spectrometry (LC/MS/MS) to identify proteins differentially expressed during BMP-2-induced chondrogenic differentiation of MEFs. We found 85 downregulated proteins, and ingenuity pathways analysis (IPA) revealed a protein-protein network with chromodomain-helicase-DNA-binding protein 4 (Chd4) in the center. Chromatin immunoprecipitation (ChIP) and nuclease hypersensitivity assays showed that Chd4, interacting with Hdac1/2, cooperates with its related proteins Kap1 and Cbx1 to bind at -207/-148 of the Sox9 promoter. We also provided evidence that let-7a targets the 3'UTR of Chd4 to promote chondrogenesis of MEFs. Together, our findings indicate that BMP-2 induced the upregulation of let-7a, targeting Chd4 and positively controlling the chondrogenic differentiation of MEFs. These findings illustrate epigenetic regulation of the chondrogenic differentiation process and also expand the understanding of the involved intracellular mechanisms. Show less

Long-chain n-3 polyunsaturated fatty acids (PUFAs) can derive from diet or from α-linolenic acid (ALA) by elongation and desaturation. We investigated the association of common genetic variation with plasma phospholipid levels of the four major n-3 PUFAs by performing genome-wide association studies in five population-based cohorts comprising 8,866 subjects of European ancestry. Minor alleles of SNPs in FADS1 and FADS2 (desaturases) were associated with higher levels of ALA (p = 3 x 10⁻⁶⁴) and lower levels of eicosapentaenoic acid (EPA, p = 5 x 10⁻⁵⁸) and docosapentaenoic acid (DPA, p = 4 x 10⁻¹⁵⁴). Minor alleles of SNPs in ELOVL2 (elongase) were associated with higher EPA (p = 2 x 10⁻¹²) and DPA (p = 1 x 10⁻⁴³) and lower docosahexaenoic acid (DHA, p = 1 x 10⁻¹⁵). In addition to genes in the n-3 pathway, we identified a novel association of DPA with several SNPs in GCKR (glucokinase regulator, p = 1 x 10⁻⁸). We observed a weaker association between ALA and EPA among carriers of the minor allele of a representative SNP in FADS2 (rs1535), suggesting a lower rate of ALA-to-EPA conversion in these subjects. In samples of African, Chinese, and Hispanic ancestry, associations of n-3 PUFAs were similar with a representative SNP in FADS1 but less consistent with a representative SNP in ELOVL2. Our findings show that common variation in n-3 metabolic pathway genes and in GCKR influences plasma phospholipid levels of n-3 PUFAs in populations of European ancestry and, for FADS1, in other ancestries. Show less

The intense inhomogeneous magnetic fields acting on the diamagnetic materials naturally present in cells can generate strong magnetic forces. We have developed a superconducting magnet platform with large gradient high magnetic field (LG-HMF), which can produce three magnetic force fields of -1360, 0, and 1312 T(2)/m, and three corresponding apparent gravity levels, namely 0, 1, and 2-g for diamagnetic materials. In this study, the effects of different magnetic force fields on osteoblast-like cells (MG-63 and MC3T3-E1) viability, microtubule actin crosslinking factor 1 (MACF1) expression and its association with cytoskeleton were investigated. Results showed that cell viability increased to different degrees after exposure to 0 or 1-g conditions for 24 h, but it decreased by about 30% under 2-g conditions compared with control conditions. An increase in MACF1 expression at the RNA or protein level was observed in osteoblast-like cells under the magnetic force field of -1360 T(2)/m (0-g) relative to 1312 T(2)/m (2-g). Under control conditions, anti-MACF1 staining was scattered in the cytoplasm and partially colocalized with actin filaments (AFs) or microtubules (MTs) in the majority of osteoblast-like cells. Under 0-g conditions, MACF1 labeling was concentrated at perinuclear region and colocalization was not apparent. The patterns of anti-MACF1 labeling on MTs varied with MTs' changing under LG-HMF environment. In conclusion, LG-HMF affects osteoblast-like cell viability, MACF1 distribution, expression, and its association with cytoskeleton to some extent. Show less

To seek differentially expressed serum proteins in recovered SARS patients complicating avascular necrosis of femoral head (AVNFH). 2-DE and MALDI-TOF MS were used to study the comparative serum proteomics among female SARS AVNFH group, female SARS non-AVNFH group and female healthy group. ELISA method was used to detect serum amyloid P component in individual serum; specificity and sensitivity of serum amyloid P component were analyzed. Average protein points on 2-DE of 3 groups were 632 +/- 28, 671 +/- 55, 688 +/- 42 respectively, and the matching rate of protein points was ranged from 85% to 95%; eighteen differentially expressed proteins were discovered including transthyretin, serpin peptidase inhibitor, alpha-1-antitrypsin precursor, serum amyloid P components, etc. Compared to healthy group and SARS non-AVNFH group, transthyretin, C4B3, fibrinogen gamma, apolipoprotein L, apolipoprotein A-IV precursor, albumin and prealbumin showed lower expression, inversely serpin peptidase inhibitor, alpha-1-antitrypsin precursor and serum amyloid P components showed higher expression in serum in the SARS AVNFH necrosis group. The serum amyloid P component in 3 groups were 0.54 +/- 0.30 ng/ml, 0.83 +/- 0.39 ng/ml, 1.21 +/- 0.29 ng/ml respectively. The areas under the ROC curve on serum amyloid P component was 0.854, the specificity was 77.8% and the sensitivity was 85.2%. There were differentially expressed serum proteins in three groups. Serum amyloid P components might be one of the potential biomarkers in serum of recovered SARS patients complicating avascular necrosis of femoral head. Show less