Evidence for sequence-dependent and reversible nonspecific effects of PS-capped antisense treatment after intracerebral administration

Phosphorothioate (PS)-capped phosphodiester (PE) oligodeoxynucleotides (ODNs) were used to determine whether the dopamine-dependent locomotor-stimulant effect of nicotine is mediated via a4 subunit-containing nicotinic receptors. To this end, rats received direct intraventral tegmental area infusion of a4 antisense via osmotic minipump, and their locomotor response to nicotine (0.2 mg/kg, s.c.) was tested. Eight antisense ODNs were screened, but only one inhibited nicotine-induced locomotion. This inhibition was reversible and selective, insofar as basal (saline) activity was unaffected, and a mismatch ODN was without effect. However, antisense treatment also caused sequence-dependent toxic effects, including neuronal degeneration in the ventral tegmental area, dopaminergic denervation, and weight loss. We conclude that despite previous reports, PS-capped PE-ODNs can cause severe neurotoxicity on chronic infusion into brain tissue. Moreover, sequence dependence and temporal reversibility, two generally accepted criteria of antisense action, may sometimes reflect the occurrence of toxic effects and resultant functional compensation.     

Eliminating expression of erucic acid-encoding loci allows the identification of “hidden” QTL contributing to oil quality fractions and oil content in <Emphasis Type="Italic">Brassica juncea</Emphasis> (Indian mustard)

Oil content and oil quality fractions (viz., oleic, linoleic and linolenic acid) are strongly influenced by the erucic acid pathway in oilseed Brassicas. Low levels of erucic acid in seed oil increases oleic acid content to nutritionally desirable levels, but also increases the linoleic and linolenic acid fractions and reduces oil content in Indian mustard (Brassica juncea). Analysis of phenotypic variability for oil quality fractions among a high-erucic Indian variety (Varuna), a low-erucic east-European variety (Heera) and a zero-erucic Indian variety (ZE-Varuna) developed by backcross breeding in this study indicated that lower levels of linoleic and linolenic acid in Varuna are due to substrate limitation caused by an active erucic acid pathway and not due to weaker alleles or enzyme limitation. To identify compensatory loci that could be used to increase oil content and maintain desirable levels of oil quality fractions under zero-erucic conditions, we performed Quantitative Trait Loci (QTL) mapping for the above traits on two independent F1 doubled haploid (F1DH) mapping populations developed from a cross between Varuna and Heera. One of the populations comprised plants segregating for erucic acid content (SE) and was used earlier for construction of a linkage map and QTL mapping of several yield-influencing traits in B. juncea. The second population consisted of zero-erucic acid individuals (ZE) for which, an Amplified Fragment Length Polymorphism (AFLP)-based framework linkage map was constructed in the present study. By QTL mapping for oil quality fractions and oil content in the ZE population, we detected novel loci contributing to the above traits. These loci did not co-localize with mapped locations of the fatty acid desaturase 2 (FAD2), fatty acid desaturase 3 (FAD3) or fatty acid elongase (FAE) genes unlike those of the SE population wherein major QTL were found to coincide with mapped locations of the FAE genes. Some of the new loci identified in the ZE population could be detected as ‘weak’ contributors (with LOD < 2.5) in the SE population in which their contribution to the traits was “masked” due to pleiotropic effects of erucic acid genes. The novel loci identified in this study could now be used to improve oil quality parameters and oil content in B. juncea under zero-erucic conditions.     

The putative tumor suppressor gene EphA3 fails to demonstrate a crucial role in murine lung tumorigenesis or morphogenesis

Treatment of non-small cell lung cancer (NSCLC) is based on histological analysis and molecular profiling of targetable driver oncogenes. Therapeutic responses are further defined by the landscape of passenger mutations, or loss of tumor suppressor genes. We report here a thorough study to address the physiological role of the putative lung cancer tumor suppressor EPH receptor A3 (EPHA3), a gene that is frequently mutated in human lung adenocarcinomas. Our data shows that homozygous or heterozygous loss of EphA3 does not alter the progression of murine adenocarcinomas that result from Kras mutation or loss of Trp53, and we detected negligible postnatal expression of EphA3 in adult wild-type lungs. Yet, EphA3 was expressed in the distal mesenchyme of developing mouse lungs, neighboring the epithelial expression of its Efna1 ligand; this is consistent with the known roles of EPH receptors in embryonic development. However, the partial loss of EphA3 leads only to subtle changes in epithelial Nkx2-1, endothelial Cd31 and mesenchymal Fgf10 RNA expression levels, and no macroscopic phenotypic effects on lung epithelial branching, mesenchymal cell proliferation, or abundance and localization of CD31-positive endothelia. The lack of a discernible lung phenotype in EphA3-null mice might indicate lack of an overt role for EPHA3 in the murine lung, or imply functional redundancy between EPHA receptors. Our study shows how biological complexity can challenge in vivo functional validation of mutations identified in sequencing efforts, and provides an incentive for the design of knock-in or conditional models to assign the role of EPHA3 mutation during lung tumorigenesis.KEY WORDS: EPHA3, EPH receptor A3, GEMM, Adenocarcinoma, Lung morphogenesis     

Interactions between quercetin and Warfarin for albumin binding: A new eye on food/drug interference

The interaction between quercetin, a popular antioxidant flavonoid, and human serum albumin (HSA) is investigated and characterized by means of induced circular dichroism and saturation transfer difference NMR. These techiques demonstrate the reversible binding of quercetin to the carrier protein, which is responsible for its dissolution in aqueous medium. Competition experiments with two classical probes for HSA binding sites, namely Ibuprofen and Warfarin (a common anticoagulant coumarin), demonstrate that quercetin has a primary binding site located in the subdomain IIA, where coumarins are hosted. The affinity for this site is large and we found that quercetin may effectively displace warfarin from HSA. This may have relevant consequences in rationalizing the interferences of common dietary compounds and food supplements to anticoagulant treatments. Chirality, 2010. © 2009 Wiley‐Liss, Inc.     

Identification of potential Leptospira phosphoheptose isomerase inhibitors through virtual high-throughput screening

The hfe-threatening infections caused by Leptospira serovars demand the need for designing anti-leptospirosis drugs.The present study encompasses exploring inhibitors against phosphoheptose isomerase(GmhA)of Leptospira,which is vital for lipopolysaccharide(LPS)biosynthesis and is identified as a common drug target through the subtractive genomic approach.GmhA model was built in Modeller 9v7.Structural refinement and energy minimization of the predicted model was carried out using Maestro 9.0.The refined model reliability was assessed through Procheck,ProSA,ProQ and Profile 3D.The substrate-based virtual high-throughput screening(VHTS)in Ligand.Info Meta-Database tool generated an in-house library of 354 substrate structural analogs.Furthermore,structure-based VHTS from the in-house library with different conformations of each ligand provided 14 novel competitive inhibitors.The model together with insight gained from the VHTS would be a promising starting point for developing anti-leptospirosis competitive inhibitors targeting LPS biosynthesis pathway.     

Signaling molecules involved in the transition of growth to development of Dictyostelium discoideum

The social amoeba Dictyostelium discoideum, a powerful paradigm provides clear insights into the regulation of growth and development. In addition to possessing complex individual cellular functions like a unicellular eukaryote, D. discoideum cells face the challenge of multicellular development. D. discoideum undergoes a relatively simple differentiation process mainly by cAMP mediated pathway. Despite this relative simplicity, the regulatory signaling pathways are as complex as those seen in metazoan development. However, the introduction of restriction-enzyme-mediated integration (REMI) technique to produce developmental gene knockouts has provided novel insights into the discovery of signaling molecules and their role in D. discoideum development. Cell cycle phase is an important aspect for differentiation of D. discoideum, as cells must reach a specific stage to enter into developmental phase and specific cell cycle regulators are involved in arresting growth phase genes and inducing the developmental genes. In this review, we present an overview of the signaling molecules involved in the regulation of growth to differentiation transition (GDT), molecular mechanism of early developmental events leading to generation of cAMP signal and components of cAMP relay system that operate in this paradigm.     

A family of amphiphilic dioxidovanadium(V) hydrazone complexes as potent carbonic anhydrase inhibitors along with anti-diabetic and cytotoxic activities

BioMetals - A family of dioxidovanadium(V) complexes (1–4) of the type [Na(H2O)x]+[VVO2(HL1?4)]? (x?=?4, 4.5 and 7) where HL2? represents the dianionic form of...