Death-associated protein 5 (DAP5/p97/NAT1) contributes to retinoic acid-induced granulocytic differentiation and arsenic trioxide-induced apoptosis in acute promyelocytic leukemia

All-trans-retinoic acid (ATRA) and arsenic trioxide (ATO) induce differentiation and apoptosis in acute promyelocytic leukemia (APL) cells. Here we investigated the role and regulation of death-associated protein-5 (DAP5/p97/NAT1), a novel inhibitor of translational initiation, in APL cell differentiation and apoptosis. We found that ATRA markedly induced DAP5/p97 protein and gene expression and nuclear translocation during terminal differentiation of APL (NB4) and HL60 cells but not differentiation-resistant cells (NB4.R1 and HL60R), which express very low levels of DAP5/p97. At the differentiation inducing concentrations, ATO (<0.5 μM), dimethyl sulfoxide, 1,25-dihydroxy-vitamin-D3, and phorbol-12-myristate 13-acetate also significantly induced DAP5/p97 expression in NB4 cells. However, ATO administered at apoptotic doses (1–2 μM) induced expression of DAP5/p86, a proapoptotic derivative of DAP5/p97. ATRA and ATO-induced expression of DAP5/p97 was associated with inhibition of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. Furthermore, DAP5/p97 expression was upregulated by inhibition of the PI3K/Akt/mammalian target of rapamycin (mTOR) pathway via LY294002 and via rapamycin. Finally, knockdown of DAP5/p97 expression by small interfering RNA inhibited ATRA-induced granulocytic differentiation and ATO-induced apoptosis. Together, our data reveal new roles for DAP5/p97 in ATRA-induced differentiation and ATO-induced apoptosis in APL and suggest a novel regulatory mechanism by which PI3K/Akt/mTOR pathway inhibition mediates ATRA- and ATO-induced expression of DAP5/p97. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. B. Ozpolat and U. Akar contributed equally.     

Vegetable oils used as vitamin E vehicle affect the electrical activity of the rat heart

The aim of this study is to define the possible effects of vegetable oils used as vitamin E vehicle on the electrical activity of the rat heart. To test the possible effects of vitamin E vehicles we studied the effect of i.p. injected corn oil, hazelnut oil or peanut oil on the action potential parameters recorded in both papillary and left atrial muscle strips. Four experimental groups were used. The control group was injected (i.p.) with distilled water, while the three remaining groups received injections of corn oil, hazelnut oil, or peanut oil for five weeks (in a dose of 0.4 ml/kg/day--minimum amount of oil in which vitamin E could be dissolved). We used borosilicated (15-20 megaohms) capillary electrodes and intracellular action potentials (AP) were recorded in isolated papillary and left atrium muscle strips. While administration of three different types of vegetable oil had no significant effect on AP parameters of papillary muscle, they significantly prolonged the repolarization phase of AP in atrial strips. These results show that vegetable oils used as vitamin E vehicles may alter the electrical activity of the heart in a tissue-dependent manner. The present data indicate that the possible effect of vegetable oil vehicles should be kept in mind while evaluating the possible effects of in vivo vitamin E administration.     

Effect of codon optimization on the expression of Trichoderma reesei endoglucanase 1 in Pichia pastoris

Trichoderma reesei cellulases are important biocatalysts for a wide range of industrial applications that include the paper, feed, and textile industries. T. reesei endoglucanase 1 (egl1) was successfully expressed as an active and stable catalyst in Pichia pastoris for the first time. Codon optimization was applied to egl1 of T. reesei to enhance its expression levels in P. pastoris. When compared with the originally cloned egl1 gene of T. reesei, the synthetic codon optimized egl1 gene (egl1s) was expressed at a higher level in P. pastoris. Batch fermentations of both clones with the same copy number under controlled conditions indicated that codon optimized EGI enzyme activity increased to 1.24 fold after 72 h of methanol induction. Our research indicated that P. pastoris is a suitable host for cellulase production.     

The Identification of Pathway Markers in Intracranial Aneurysm Using Genome-Wide Association Data from Two Different Populations

The identification of significant individual factors causing complex diseases is challenging in genome-wide association studies (GWAS) since each factor has only a modest effect on the disease development mechanism. In this study, we hypothesize that the biological pathways that are targeted by these individual factors show higher conservation within and across populations. To test this hypothesis, we searched for the disease related pathways on two intracranial aneurysm GWAS in European and Japanese case–control cohorts. Even though there were a few significantly conserved SNPs within and between populations, seven of the top ten affected pathways were found significant in both populations. The probability of random occurrence of such an event is 2.44E−36. We therefore claim that even though each individual has a unique combination of factors involved in the mechanism of disease development, most targeted pathways that need to be altered by these factors are, for the most part, the same. These pathways can serve as disease markers. Individuals, for example, can be scanned for factors affecting the genes in marker pathways. Hence, individual factors of disease development can be determined; and this knowledge can be exploited for drug development and personalized therapeutic applications. Here, we discuss the potential avenues of pathway markers in medicine and their translation to preventive and individualized health care.     

Effect of Time on Endothelium-Dependent Relaxations in Mice and Rat Thoracic Aortas

Temporal variations in the endothelium-dependent relaxant effects of acetylcholine (ACh) in mice and histamine (HA) in rat thoracic aorta have been studied. The relaxations induced by higher concentrations of ACh and HA were significantly dependent on the time the tissues were obtained. However, neither EC 50 (the concentration inducing half of the maximum response) values for ACh and HA, nor K B (antagonist dissociation constant) values for atropine and diphenhydramine were found to be statistically significant depending upon the time of obtaining aorta preparations. These results show that the in vitro responsiveness of mice and rat thoracic aortas to endothelium-dependent relaxant effects of ACh and HA, respectively, changes over a 24-h period. These variations might be dependent on a temporal rhythm in post-receptor events, i.e., guanylate cyclase-cGMP-phosphodiesterase system which mediates responses to endothelium-derived relaxing factor(s).     

Apolipoprotein A-V: a potential modulator of plasma triglyceride levels in Turks

The apolipoprotein A-V gene (APOA5) plays an important role in determining plasma triglyceride levels. We studied the effects of APOA5 polymorphisms on plasma triglyceride levels in Turks, a population with low levels of HDL cholesterol and a high prevalence of coronary artery disease. We found 15 polymorphisms, three of which were novel. Seven haplotype-tagging single nucleotide polymorphisms (SNPs) were chosen and genotyped in approximately 3,000 subjects. The rare alleles of the -1464T>C, -1131T>C, S19W, and 1259T>C SNPs were significantly associated with increased triglyceride levels (19-86 mg/dl; P < 0.05) and had clear gene-dose effects. Haplotype analysis of the nine common APOA5 haplotypes revealed significant effects on triglyceride levels (P < 0.001). Detailed analysis of haplotypes clearly showed that the -1464T>C polymorphism had no effect by itself but was a marker for the -1131T>C, S19W, and 1259T>C polymorphisms. The -1131T>C and 1259T>C polymorphisms were in a strong but incomplete linkage disequilibrium and appeared to have independent effects. Thus, the APOA5 -1131T>C, S19W, and 1259T>C rare alleles were associated with significant increases in plasma triglyceride levels. At least one of these alleles was present in approximately 40% of the Turks. Similar associations were observed for -1131T>C and S19W in white Americans living in San Francisco, California.