GAGA Regulates Border Cell Migration in Drosophila.

Collective cell migration is a complex process that happens during normal development of many multicellular organisms, as well as during oncological transformations. In Drosophila oogenesis, a small set of follicle cells originally located at the anterior tip of each egg chamber become motile and migrate as a cluster through nurse cells toward the oocyte. These specialized cells are referred to as border cells (BCs) and provide a simple and convenient model system to study collective cell migration. The process is known to be complexly regulated at different levels and the product of the slow border cells (slbo) gene, the C/EBP transcription factor, is one of the key elements in this process. However, little is known about the regulation of slbo expression. On the other hand, the ubiquitously expressed transcription factor GAGA, which is encoded by the Trithorax-like (Trl) gene was previously demonstrated to be important for Drosophila oogenesis. Here, we found that Trl mutations cause substantial defects in BC migration. Partially, these defects are explained by the reduced level of slbo expression in BCs. Additionally, a strong genetic interaction between Trl and slbo mutants, along with the presence of putative GAGA binding sites within the slbo promoter and enhancer, suggests the direct regulation of this gene by GAGA. This idea is supported by the reduction in the slbo-Gal4-driven GFP expression within BC clusters in Trl mutant background. However, the inability of slbo overexpression to compensate defects in BC migration caused by Trl mutations suggests that there are other GAGA target genes contributing to this process. Taken together, the results define GAGA as another important regulator of BC migration in Drosophila oogenesis.

GAGA protein is required for multiple aspects of Drosophila oogenesis and female fertility.

Investigation of Drosophila oogenesis provides the opportunity to understand conservative genetic mechanisms underlying fertile female gamete development. In this study, we showed that the Drosophila DNA-binding protein GAGA factor (GAF) had a multifunctional role in oogenesis and it is involved in the regulation of this process genetic program. We studied the influence on Drosophila oogenesis of a number of mutations in the 5' region of the Trl gene that encodes GAF. We found that our originally generated Trl mutations lead to a decrease in transcriptional gene activity and levels of GAF expression in both germline and follicular cells. Cytological (fluorescence and electron microscopy) analysis showed that GAF loss resulted in multiple oogenesis defects. Mutations affected the actin cytoskeleton, leading to decrease of cytoplasmic filaments in nurse cells and basal actin in follicular cells. GAF depletion also leads to abnormal follicular cells migration, both border and centripetal. In addition, mutant ovaries demonstrated abnormalities in germ cells, including mitochondria, endoplasmic reticulum, karyosome organization, yolk granule formation and selective transport. Loss of GAF also promoted excessive cell death and egg chamber degradation. In sum, these defects caused very high or full female sterility. Since one of the main GAF activities is regulation of transcription, the complex phenotypes of the Trl mutants might be the consequence of its multiple target genes misexpression.

New slbo-Gal4 driver lines for the analysis of border cell migration during Drosophila oogenesis.

Border cell (BC) migration during Drosophila oogenesis is an excellent model for the analysis of the migratory and invasive cell behavior. Most studies on BC migration have exploited a slbo-Gal4 driver to regulate gene expression in these cells or to mark them. Here, we report that the slbo-Gal4 transgene present in the line #6458 from the Bloomington Stock Center is inserted within chickadee (chic), a gene encoding the actin-binding protein Profilin, which promotes actin polymerization and is known to be involved in cell migration. The chic6458 mutation caused by the transgene insertion behaves as a null chic allele and is homozygous lethal. To evaluate possible effects of chic6458 on the assessment of BC behavior, we generated new lines bearing the slbo-Gal4 transgene inserted into different second chromosome loci that do not appear to be involved in cell migration. Using these new lines and the slbo-Gal4-chic6458 line, we defined the functional relationships between the twinfilin (twf) and chic in BC migration. Migration of BCs is substantially reduced by mutations in twf, which encodes an actin-binding protein that inhibits actin filament assembly. The defects caused by twf mutations are significantly suppressed when the slbo-Gal4-chic6458, but not the new slbo-Gal4 drivers were used. These findings indicate twf and chic interact and function antagonistically during BC migration in Drosophila oogenesis.

Assessment of the Potential Biological Activity of Low Molecular Weight Metabolites of Freshwater Macrophytes with QSAR.

The paper focuses on the assessment of the spectrum of biological activities (antineoplastic, anti-inflammatory, antifungal, and antibacterial) with PASS (Prediction of Activity Spectra for Substances) for the major components of three macrophytes widespread in the Holarctic species of freshwater, emergent macrophyte with floating leaves, Nuphar lutea (L.) Sm., and two species of submergent macrophyte groups, Ceratophyllum demersum L. and Potamogeton obtusifolius (Mert. et Koch), for the discovery of their ecological and pharmacological potential. The predicted probability of anti-inflammatory or antineoplastic activities above 0.8 was observed for twenty compounds. The same compounds were also characterized by high probability of antifungal and antibacterial activity. Six metabolites, namely, hexanal, pentadecanal, tetradecanoic acid, dibutyl phthalate, hexadecanoic acid, and manool, were a part of the major components of all three studied plants, indicating their high ecological significance and a certain universalism in their use by various species of water plants for the implementation of ecological and biochemical functions. This report underlines the role of identified compounds not only as important components in regulation of biochemical and metabolic pathways and processes in aquatic ecological systems, but also as potential pharmacological agents in the fight against different diseases.

Design, synthesis and pharmacological evaluation of novel vanadium-containing complexes as antidiabetic agents.

Based on the data about structure and antidiabetic activity of twenty seven vanadium and zinc coordination complexes collected from literature we developed QSAR models using the GUSAR program. These QSAR models were applied to 10 novel vanadium coordination complexes designed in silico in order to predict their hypoglycemic action. The five most promising substances with predicted potent hypoglycemic action were selected for chemical synthesis and pharmacological evaluation. The selected coordination vanadium complexes were synthesized and tested in vitro and in vivo for their hypoglycemic activities and acute rat toxicity. Estimation of acute rat toxicity of these five vanadium complexes was performed using a freely available web-resource (http://way2drug.com/GUSAR/acutoxpredict.html). It has shown that the selected compounds belong to the class of moderate toxic pharmaceutical agents, according to the scale of Hodge and Sterner. Comparison with the predicted data has demonstrated a reasonable correspondence between the experimental and predicted values of hypoglycemic activity and toxicity. Bis{tert-butyl[amino(imino)methyl]carbamato}oxovanadium (IV) and sodium(2,2'-Bipyridyl)oxo-diperoxovanadate(V) octahydrate were identified as the most potent hypoglycemic agents among the synthesized compounds.

GAGA protein is essential for male germ cell development in Drosophila.

The Drosophila Trithorax-like (Trl) gene encodes a GAGA factor which regulates a number of developmentally important genes. In this study, we identify a new function for Drosophila GAGA factor in male germ cell development. Trl mutants carrying strong hypomorphic alleles display loss of primordial germ cells during their migration in embryogenesis and severe disruption in mitochondria structure during early spermatogenesis. The mutation resulted in small testes formation, a deficit of germ cells, abnormal mitochondrial morphogenesis, spermatocyte death through autophagy, and partial or complete male sterility. Pleiotropic mutation effects can be explained by the misexpression of GAGA factor target genes, the products of which are required for germ cell progression into mature sperm.