Meteorin regulates mesendoderm development by enhancing nodal expression

During gastrulation, distinct lineage specification into three germ layers, the mesoderm, endoderm and ectoderm, occurs through an elaborate harmony between signaling molecules along the embryonic proximo-distal and anterior-posterior axes, and Nodal signaling plays a key role in the early embryonic development governing embryonic axis formation, mesoderm and endoderm specification, and left-right asymmetry determination. However, the mechanism by which Nodal expression is regulated is largely unknown. Here, we show that Meteorin regulates Nodal expression and is required for mesendoderm development. It is highly expressed in the inner cell mass of blastocysts and further in the epiblast and extra-embryonic ectoderm during gastrulation. Genetic ablation of the Meteorin gene resulted in early embryonic lethality, presumably due to impaired lineage allocation and subsequent cell accumulation. Embryoid body culture using Meteorin-null embryonic stem (ES) cells showed reduced Nodal expression and concomitant impairment of mesendoderm specification. Meteorin-null embryos displayed reduced levels of Nodal transcripts before the gastrulation stage, and impaired expression of Goosecoid, a definitive endoderm marker, during gastrulation, while the proximo-distal and anterior-posterior axes and primitive streak formation were preserved. Our results show that Meteorin is a novel regulator of Nodal transcription and is required to maintain sufficient Nodal levels for endoderm formation, thereby providing new insights in the regulation of mesendoderm allocation.open1113sciescopu

A novel tumor suppressor gene ECRG4 interacts directly with TMPRSS11A (ECRG1) to inhibit cancer cell growth in esophageal carcinoma

<p>Abstract</p> <p>Background</p> <p>The esophageal carcinoma related gene 4 (ECRG4) was initially identified and cloned from human normal esophageal epithelium in our laboratory (GenBank accession no.<ext-link ext-link-id="AF325503" ext-link-type="gen">AF325503</ext-link>). ECRG4 has been described as a novel tumor suppressor gene associated with prognosis in esophageal squamous cell carcinoma (ESCC).</p> <p>Methods</p> <p>In this study, binding affinity assay in vitro and co-immunoprecipitation experiment in vivo were utilized to verify the physical interaction between ECRG4 and transmembrane protease, serine 11A (TMPRSS11A, also known as ECRG1, GenBank accession no. <ext-link ext-link-id="AF 071882" ext-link-type="gen">AF 071882</ext-link>). Then, p21 protein expression, cell cycle and cell proliferation regulations were examined after ECRG4 and ECRG1 co-transfection in ESCC cells.</p> <p>Results</p> <p>We revealed for the first time that ECRG4 interacted directly with ECRG1 to inhibit cancer cell proliferation and induce cell cycle G1 phase block in ESCC. Binding affinity and co-immunoprecipitation assays demonstrated that ECRG4 interacted directly with ECRG1 in ESCC cells. Furthermore, the ECRG4 and ECRG1 co-expression remarkably upregulatd p21 protein level by Western blot (P < 0.001), induced cell cycle G1 phase block by flow cytometric analysis (P < 0.001) and suppressed cell proliferation by MTT and BrdU assay (both P < 0.01) in ESCC cells.</p> <p>Conclusions</p> <p>ECRG4 interacts directly with ECRG1 to upregulate p21 protein expression, induce cell cycle G1 phase block and inhibit cancer cells proliferation in ESCC.</p

Impaired growth in rural Gambian infants exposed to aflatoxin: a prospective cohort study

Background: Exposure to aflatoxin, a mycotoxin produced by fungi that commonly contaminates cereal crops across sub-Saharan Africa, has been associated with impaired child growth. We investigated the impact of aflatoxin exposure on the growth of Gambian infants from birth to two years of age, and the impact on insulin-like growth factor (IGF)-axis proteins. Methods: A subsample (N = 374) of infants from the Early Nutrition and Immune Development (ENID) trial (ISRCTN49285450) were included in this study. Aflatoxin-albumin adducts (AF-alb) were measured in blood collected from infants at 6, 12 and 18 months of age. IGF-1 and IGFBP-3 were measured in blood collected at 12 and 18 months. Anthropometric measurements taken at 6, 12, 18 and 24 months of age were converted to z-scores against the WHO reference. The relationship between aflatoxin exposure and growth was analysed using multi-level modelling. Results: Inverse relationships were observed between lnAF-alb and length-for-age (LAZ), weight-for-age (WAZ), and weight-for-length (WLZ) z-scores from 6 to 18 months of age (β = − 0·04, P = 0·015; β = − 0·05, P = 0.003; β = − 0·06, P = 0·007; respectively). There was an inverse relationship between lnAF-alb at 6 months and change in WLZ between 6 and 12 months (β = − 0·01; P = 0·013). LnAF-alb at 12 months was associated with changes in LAZ and infant length between 12 and 18 months of age (β = − 0·01, P = 0·003; β = − 0·003, P = 0·02; respectively). LnAF-alb at 6 months was associated with IGFBP-3 at 12 months (r = − 0·12; P = 0·043). Conclusions: This study found a small but significant effect of aflatoxin exposure on the growth of Gambian infants. This relationship is not apparently explained by aflatoxin induced changes in the IGF-axis

Cleavage of ST6Gal I by Radiation-Induced BACE1 Inhibits Golgi-Anchored ST6Gal I-Mediated Sialylation of Integrin β1 and Migration in Colon Cancer Cells

<p>Abstract</p> <p>Background</p> <p>Previously, we found that β-galactoside α2,6-sialyltransferase (ST6Gal I), an enzyme that adds sialic acids to N-linked oligosaccharides of glycoproteins and is frequently overexpressed in cancer cells, is up-regulated by ionizing radiation (IR) and cleaved to a form possessing catalytic activity comparable to that of the Golgi-localized enzyme. Moreover, this soluble form is secreted into the culture media. Induction of ST6Gal I significantly increased the migration of colon cancer cells via sialylation of integrin β1. Here, we further investigated the mechanisms underlying ST6Gal I cleavage, solubilization and release from cells, and addressed its functions, focusing primarily on cancer cell migration.</p> <p>Methods</p> <p>We performed immunoblotting and lectin affinity assay to analyze the expression of ST6 Gal I and level of sialylated integrin β1. After ionizing radiation, migration of cells was measured by in vitro migration assay. α2, 6 sialylation level of cell surface was analyzed by flow cytometry. Cell culture media were concentrated and then analyzed for soluble ST6Gal I levels using an α2, 6 sialyltransferase sandwich ELISA.</p> <p>Result</p> <p>We found that ST6Gal I was cleaved by BACE1 (β-site amyloid precursor protein-cleaving enzyme), which was specifically overexpressed in response to IR. The soluble form of ST6Gal I, which also has sialyltransferase enzymatic activity, was cleaved from the Golgi membrane and then released into the culture media. Both non-cleaved and cleaved forms of ST6Gal I significantly increased colon cancer cell migration in a sialylation-dependent manner. The pro-migratory effect of the non-cleaved form of ST6Gal I was dependent on integrin β1 sialylation, whereas that of the cleaved form of ST6Gal I was not, suggesting that other intracellular sialylated molecules apart from cell surface molecules such as integrin β1 might be involved in mediating the pro-migratory effects of the soluble form of ST6Gal I. Moreover, production of soluble form ST6Gal I by BACE 1 inhibited integrin β1 sialylation and migration by Golgi-anchored form of ST6Gal I.</p> <p>Conclusions</p> <p>Our results suggest that soluble ST6Gal I, possibly in cooperation with the Golgi-bound form, may participate in cancer progression and metastasis prior to being secreted from cancer cells.</p

APOE Genotype-Function Relationship: Evidence of −491 A/T Promoter Polymorphism Modifying Transcription Control but Not Type 2 Diabetes Risk

BACKGROUND: The apolipoprotein E gene (APOE) coding polymorphism modifies the risks of Alzheimer's disease, type 2 diabetes, and coronary heart disease. Aside from the coding variants, single nucleotide polymorphism (SNP) of the APOE promoter has also been shown to modify the risk of Alzheimer's disease. METHODOLOGY/PRINCIPAL FINDINGS: In this study we investigate the genotype-function relationship of APOE promoter polymorphism at molecular level and at physiological level: i.e., in transcription control of the gene and in the risk of type 2 diabetes. In molecular studies, the effect of the APOE -491A/T (rs449647) polymorphism on gene transcription was accessed by dual-luciferase reporter gene assays. The -491 A to T substitution decreased the activity (p<0.05) of the cloned APOE promoter (-1017 to +406). Using the -501 to -481 nucleotide sequence of the APOE promoter as a 'bait' to screen the human brain cDNA library by yeast one-hybrid system yielded ATF4, an endoplasmic reticulum stress response gene, as one of the interacting factors. Electrophoretic-mobility-shift assays (EMSA) and chromatin immuno-precipitation (ChIP) analyses further substantiated the physical interaction between ATF4 and the APOE promoter. Over-expression of ATF4 stimulated APOE expression whereas siRNA against ATF4 suppressed the expression of the gene. However, interaction between APOE promoter and ATF4 was not -491A/T-specific. At physiological level, the genotype-function relationship of APOE promoter polymorphism was studied in type 2 diabetes. In 630 cases and 595 controls, three APOE promoter SNPs -491A/T, -219G/T (rs405509), and +113G/C (rs440446) were genotyped and tested for association with type 2 diabetes in Hong Kong Chinese. No SNP or haplotype association with type 2 diabetes was detected. CONCLUSIONS/SIGNIFICANCE: At molecular level, polymorphism -491A/T and ATF4 elicit independent control of APOE gene expression. At physiological level, no genotype-risk association was detected between the studied APOE promoter SNPs and type 2 diabetes in Hong Kong Chinese

R497K polymorphism in epidermal growth factor receptor gene is associated with the risk of acute coronary syndrome

<p>Abstract</p> <p>Background</p> <p>Previous studies suggested that genetic polymorphisms in the epidermal growth factor receptor (EGFR) gene had been implicated in the susceptibility to some tumors and inflammatory diseases. EGFR has been recently implicated in vascular pathophysiological processes associated with excessive remodeling and atherosclerosis. Acute coronary syndrome (ACS) is a clinical manifestation of preceding atherosclerosis. Our purpose was to investigate the association of the EGFR polymorphism with the risk of ACS. In this context, we analyzed the HER-1 R497K and EGFR intron 1 (CA)_nrepeat polymorphisms in 191 patients with ACS and 210 age- and sex-matched controls in a Chinese population, using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) strategy and direct sequencing.</p> <p>Results</p> <p>There were significant differences in the genotype and allele distribution of R497K polymorphism of the EGFR gene between cases and controls. The <it>Lys </it>allele had a significantly increased risk of ACS compared with the <it>Arg </it>allele (adjusted OR = 1.49, 95% CI: 1.12–1.98, adjusted <it>P </it>= 0.006). However, no significant relationship between the number of (CA)_nrepeats of EGFR intron 1 (both alleles < 20 or any allele ≥ 20) and the risk of ACS was observed (adjusted OR = 0.97, 95% CI: 0.58–1.64, adjusted <it>P </it>= 0.911). Considering these two polymorphisms together, there was no statistically significant difference between the two groups.</p> <p>Conclusion</p> <p>R497K polymorphism of the EGFR gene is significantly associated with the risk of ACS. Our data suggests that R497K polymorphism may be used as a genetic susceptibility marker of the ACS.</p