Genetic variants modify the effect of age on APOE methylation in the Genetics of Lipid Lowering Drugs and Diet Network study

Although apolipoprotein E (APOE) variants are associated with age-related diseases, the underlying mechanism is unknown and DNA methylation may be a potential one. With methylation data, measured by the Infinium Human Methylation 450 array, from 993 participants (age ranging from 18 to 87 years) in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) study, and from Encyclopedia of DNA Elements (ENCODE) consortium, combined with published methylation datasets, we described the methylation pattern of 13 CpG sites within APOE locus, their correlations with gene expression across cell types, and their relationships with age, plasma lipids, and sequence variants. Based on methylation levels and the genetic regions, we categorized the 13 APOE CpG sites into three groups: Group 1 showed hypermethylation (> 50%) and were located in the promoter region, Group 2 exhibited hypomethylation (< 50%) and were located in the first two exons and introns, and Group 3 showed hypermethylation (> 50%) and were located in the exon 4. APOE methylation was negatively correlated with gene expression (minimum r = −0.66, P = 0.004). APOE methylation was significantly associated with age (minimum P = 2.06E-08) and plasma total cholesterol (minimum P = 3.53E-03). Finally, APOE methylation patterns differed across APOE ε variants (minimum P = 3.51E-05) and the promoter variant rs405509 (minimum P = 0.01), which further showed a significant interaction with age (P = 0.03). These findings suggest that methylation may be a potential mechanistic explanation for APOE functions related to aging and call for further molecular mechanistic studies.     

The Arf GAP CNT-2 regulates the apoptotic fate in C. elegans asymmetric neuroblast divisions

During development, all cells make the decision to live or die. Although the molecular mechanisms that execute the apoptotic program are well defined, less is known about how cells decide whether to live or die. In C.?elegans, this decision is linked to how cells divide asymmetrically [1, 2]. Several classes of molecules are known to regulate asymmetric cell divisions in metazoans, yet these molecules do not appear to control C.?elegans divisions that produce apoptotic cells [3]. We identified CNT-2, an Arf GTPase-activating protein (GAP) of the AGAP family, as a novel regulator of this type of neuroblast division. Loss of CNT-2 alters daughter cell size and causes the apoptotic cell to adopt the fate of its sister cell, resulting in extra neurons. CNT-2's Arf GAP activity is essential for its function in these divisions. The N terminus of CNT-2, which contains?a GTPase-like domain that defines the AGAP class of Arf GAPs, negatively regulates CNT-2's function. We provide evidence that CNT-2 regulates receptor-mediated endocytosis and consider the implications of its role in asymmetric cell divisions.     

Pharmacophore-based discovery of triaryl-substituted imidazole as new telomeric G-quadruplex ligand

Discovery of potent and selective ligands for telomeric G-quadruplex DNA is a challenging work. Through a combination approach of pharmacophore model construction, model validation, database virtual screening, chemical synthesis and interaction evaluation, we discovered and confirmed triaryl-substituted imidazole TSIZ01 to be a new telomeric G-quadruplex ligand with potent binding and stabilizing activity to G-quadruplex DNA, as well as a 8.7-fold selectivity towards telomeric G-quadruplex DNA over duplex DNA.     

Design, synthesis, and biological evaluation of curcumin analogues as multifunctional agents for the treatment of Alzheimer's disease

A series of novel curcumin analogues were designed, synthesized, and evaluated as potential multifunctional agents for the treatment of AD. The in vitro studies showed that these compounds had better inhibitory properties against Aβ aggregation than curcumin. Superior anti-oxidant properties (better than the reference compound Trolox) of these compounds were observed by the oxygen radical absorbance capacity (ORAC) method and a cell-based assay using DCFH-DA as a probe. In addition they were able to chelate metals such as iron and copper and decrease metal-induced Aβ aggregation. The structure-activity relationships were discussed. The results suggested that our curcumin analogues could be selected as multifunctional agents for further investigation of AD treatment.     

Identification and analysis of the gene cluster involved in biosynthesis of paenibactin, a catecholate siderophore produced by Paenibacillus elgii B69

Bacteria belonging to the genus Paenibacillus are recognized as rich sources of bioactive natural products. To date, there are few characterized siderophores from this genus. Here, through genome analysis, we identified a non-ribosomal peptide biosynthetic gene cluster (pae) responsible for siderophore assembly in Paenibacillus elgii B69. The 12.8 kb gene cluster comprises six open reading frames encoding proteins similar to the components of the bacillibactin biosynthetic machinery and bacillibactin esterase. To examine the product of the pae gene cluster, we cultured P. elgii B69 in iron-deficient medium for siderophore expression. A novel siderophore structurally similar to bacillibactin, designated paenibactin, was purified and characterized. Its structure was determined as a cyclic trimeric lactone of 2,3-dihydroxybenzoyl-alanine-threonine. The involvement of the pae gene cluster in paenibactin biosynthesis was confirmed by the biochemical assay of adenylation domain specificity. Furthermore, we demonstrated that the pae gene cluster evolves from an ancestral bacillibactin biosynthetic gene cluster via sequence and phylogenetic analyses. The structural difference between paenibactin and bacillibactin may stem from a mutation-induced change in the adenylation domain specificity. Based on these findings and published models for bacillibactin, we proposed models for paenibactin biosynthesis, ferric-paenibactin uptake and paenibactin-bounded iron release.     

Optimum induction of recombinant thymidine phosphorylase and its application

Recombinant E. coli pDEOA was constructed and lactose can be used instead of IPTG to induce the expression of thymidine phosphorylase by pDEOA. The use of lactose at concentrations higher than 0.5 mmol/L had an induction effect similar to that of IPTG but resulted in a longer initial induction time and better cell growth. The thymidine phosphorylase induced by lactose was very stable at 50°C. Intact pDEOA cells induced by lactose can be used as a source of thymidine phosphorylase. Under standard reaction conditions, several deoxynucleosides were effectively produced from thymidine.     

IFN-α/β and autophagy: tug-of-war between HCV and the host

Hepatitis C virus (HCV) infects approximately 130 million people worldwide. The clinical sequelae of this chronic disease include cirrhosis, functional failure and carcinoma of the liver. HCV induces autophagy, a fundamental cellular process for maintaining homeostasis and mediating innate immune response, and also inhibits autophagic protein degradation and suppresses antiviral immunity. In addition to this ploy, the HCV serine protease composed of the viral non-structural proteins 3/4A (NS3/4A) can enzymatically digest two cellular proteins, mitochondria-associated anti-viral signaling protein (MAVS) and Toll/interleukin-1 receptor domain containing adaptor inducing IFN-β (TRIF). Since these two proteins are the adaptor molecules in the retinoic acid-inducible gene I (RIG-I) and TLR3 pathways, respectively, their cleavage has been suggested as a pivotal mechanism by which HCV blunts the IFN-α/β signaling and antiviral responses. Thus far, how HCV perturbs autophagy and copes with IFN-α/β in the liver remains unclear.