Adenosine A<Subscript>2A</Subscript> receptor regulates expression of vascular endothelial growth factor in feto-placental endothelium from normal and late-onset pre-eclamptic pregnancies

We aim to investigate whether A_2A/nitric oxide-mediated regulation of vascular endothelial growth factor (VEGF) expression is impaired in feto-placental endothelial cells from late-onset pre-eclampsia. Cultures of human umbilical vein endothelial cells (HUVECs) and human placental microvascular endothelial cells (hPMECs) from normal and pre-eclamptic pregnancies were used. Assays by using small interference RNA (siRNA) for A_2A were performed, and transfected cells were used for estimation of messenger RNA (mRNA) levels of VEGF, as well as for cell proliferation and angiogenesis in vitro. CGS-21680 (A_2A agonist, 24 h) increases HUVEC and hPMEC proliferation in a dose response manner. Furthermore, similar to CGS-21680, the nitric oxide donor, S-nitroso-N-acetyl-penicillamine oxide (SNAP), increased cell proliferation in a dose response manner (logEC₅₀ 10^?9.2 M). In hPMEC, CGS-21680 increased VEGF protein levels in both normal (～1.5-fold) and pre-eclamptic pregnancies (～1.2-fold), an effect blocked by the A_2A antagonist, ZM-241385 (10^?5 M) and the inhibitor of NO synthase, N _ω-nitro-L-arginine methyl ester hydrochloride (L-NAME). Subsequently, SNAP partially recovered cell proliferation and in vitro angiogenesis capacity of cells from normal pregnancies exposed to siRNA for A_2A. CGS-21680 also increased (～1.5-fold) the level of VEGF mRNA in HUVEC from normal pregnancies, but not in pre-eclampsia. Additionally, transfection with siRNA for A_2A decrease (～30 %) the level of mRNA for VEGF in normal pregnancy compared to untransfected cells, an effect partially reversed by co-incubation with SNAP. The A_2A-NO-VEGF pathway is present in endothelium from microcirculation and macrocirculation in both normal and pre-eclamptic pregnancies. However, NO signaling pathway seems to be impaired in HUVEC from pre-eclampsia.     

Impaired A2A adenosine receptor/nitric oxide/VEGF signaling pathway in fetal endothelium during late- and early-onset preeclampsia

To investigate whether fetal endothelial cell proliferation and migration are modulated by the A_2A adenosine receptor (A_2AAR), nitric oxide (NO) and the vascular endothelial growth factor (VEGF) signaling pathway, we isolated human umbilical vein endothelial cells from normal pregnancy (n?=?23), preterm delivery (n?=?4), and late-onset (LOPE, n?=?10) and early-onset preeclampsia (EOPE, n?=?8). We used the non-selective adenosine receptor agonist (NECA) and the selective agonist (CGS-21680) and/or selective antagonist (ZM-241385) for A_2AAR. Also, the nitric oxide synthase (NOS) inhibitor, l-NAME, was used in co-incubation with CGS-21680. Compared to normal pregnancy, EOPE exhibited low cell proliferation and migration associated with reduced expressions of A_2AAR and VEGF and NO synthesis (i.e., total and phosphorylated serine¹¹⁷⁷ endothelial NOS and nitrite formation). In contrast, LOPE exhibited the opposite behavior in all these markers compared to normal pregnancy or EOPE. Cell proliferation and migration were increased by CGS-21680 (or NECA) in all analyzed groups (EOPE>LOPE>normal pregnancy) compared to their respective basal conditions, an effect that was associated with high NO and VEGF synthesis and blocked by ZM-241385 with significantly different IC₅₀ for each group (EOPE>LOPE>normal pregnancy). The differences seem independent of gestational age. l-NAME blocked the CGS-21680-mediated cell proliferation and migration in normal pregnancy and LOPE (IC₅₀?=?36.2?±?2.5 and 8.6?±?2.2 nM, respectively) as well as the VEGF expression in normal pregnancy. Therefore, the A_2AAR/NO/VEGF signaling pathway exhibits a pro-angiogenic effect in normal pregnancies and LOPE, whereas impairment in this pathway seems related to the reduced angiogenic capacity of the fetal endothelium in EOPE.     

Enhanced Cell Polarity in Mutants of the Budding Yeast Cyclin-dependent Kinase Cdc28p

The yeast cyclin-dependent kinase Cdc28p regulates bud morphogenesis and cell cycle progression via the antagonistic activities of Cln and Clb cyclins. Cln G1 cyclins direct polarized growth and bud emergence, whereas Clb G2 cyclins promote isotropic growth of the bud and chromosome segregation. Using colony morphology as a screen to dissect regulation of polarity by Cdc28p, we identified nine point mutations that block the apical-isotropic switch while maintaining other functions. Like a clb2 Delta mutation, each confers tubular bud shape, apically polarized actin distribution, unipolar budding, and delayed anaphase. The mutations are all suppressed by CLB2 overexpression and are synthetically lethal with a CLB2 deletion. However, defects in multiple independent pathways may underlie their common phenotype, because the mutations are scattered throughout the CDC28 sequence, complement each other, and confer diverse biochemical properties. Glu12Gly, a mutation that alters a residue involved in Swe1p inhibition of Cdc28p, was unique in being suppressed by deficiency of SWE1 or CLN1. With wild-type CDC28, filament formation induced by CLN1 overexpression was markedly decreased in a SWE1 deletion. These results suggest that Swe1p, via inhibition of Clb2p/Cdc28p, may mediate much of the effect of Cln1p on filamentous morphogenesis.     

Deletion of the adenosine A2A receptor increases the survival rate in a mice model of polymicrobial sepsis

Purinergic Signalling - We aim to investigate the role of A2A receptor in peritonitis-related sepsis by injection of a fecal solution (FS) as a model of polymicrobial infection. C57/black J6...     

High plasma adenosine levels in overweight/obese pregnant women

We aim to investigate whether overweight/obese pregnant women have elevated plasma levels of adenosine associated with increased consumption of high-calorie food. Sixty women were included. They were divided into lean (n = 23 and n = 12) or overweight/obese (n = 7 and n = 18) non-pregnant and pregnant women, respectively. Clinical records and maternal blood samples were collected after informed consent. A self-reported dietary questionnaire was also completed. Plasma adenosine levels were determined with high-performance liquid chromatography. Biochemical parameters, including glucose, total protein, and lipid profile, were determined using standard colorimetric assays. Adenosine levels were higher in pregnant women than in non-pregnant women (18.7 ± 1.6 vs 10.8 ± 1.3 nM/μg protein, respectively, p < 0.0001). Overweight/obese pregnant women (21.9 ± 2.5 nM/μg protein) exhibited higher adenosine levels than lean pregnant (14.5 ± 1.0 nM/μg protein, p = 0.04) or non-pregnant women (11.7 ± 1.5 nM/μg protein, p = 0.0005). Also, pregnant women with elevated weight gain exhibited higher (26.2 ± 3.7 nM/μg protein) adenosine levels than those with adequate weight gain (14.9 ± 1.4 nM/μg protein, p = 0.03). These differences were not statistically significant compared with those of pregnant women with reduced weight gain (17.4 ± 2.1 nM/μg protein, p = 0.053). Body mass index and adenosine only in pregnant women were positively correlated (r = 0.39, p = 0.02). While, polyunsaturated fatty acid (PUFA) consumption was negatively correlated with plasma adenosine levels only in non-pregnant women (r = ?0.33, p = 0.03). Pregnancy is associated with high plasma adenosine levels, which are further elevated in pregnant women who are overweight/obese. High PUFA intake might reduce plasma adenosine levels in non-pregnant women.     

Regulation of G2/M Progression by the STE Mitogen-activated Protein Kinase Pathway in Budding Yeast Filamentous Growth

Inoculation of diploid budding yeast onto nitrogen-poor agar media stimulates a MAPK pathway to promote filamentous growth. Characteristics of filamentous cells include a specific pattern of gene expression, elongated cell shape, polar budding pattern, persistent attachment to the mother cell, and a distinct cell cycle characterized by cell size control at G2/M. Although a requirement for MAPK signaling in filamentous gene expression is well established, the role of this pathway in the regulation of morphogenesis and the cell cycle remains obscure. We find that ectopic activation of the MAPK signal pathway induces a cell cycle shift to G2/M coordinately with other changes characteristic of filamentous growth. These effects are abrogated by overexpression of the yeast mitotic cyclins Clb1 and Clb2. In turn, yeast deficient for Clb2 or carrying cdc28-1N, an allele of CDK defective for mitotic functions, display enhanced filamentous differentiation and supersensitivity to the MAPK signal. Importantly, activation of Swe1-mediated inhibitory phosphorylation of Thr-18 and/or Tyr-19 of Cdc28 is not required for the MAPK pathway to affect the G2/M delay. Mutants expressing a nonphosphorylatable mutant Cdc28 or deficient for Swe1 exhibit low-nitrogen-dependent filamentous growth and are further induced by an ectopic MAPK signal. We infer that the MAPK pathway promotes filamentous growth by a novel mechanism that inhibits mitotic cyclin/CDK complexes and thereby modulates cell shape, budding pattern, and cell-cell connections.     

Radiation of the Drosophila nannoptera species group in Mexico

The Drosophila nannoptera species group, a taxon of Mexican cactophilic flies, is an excellent model system to study the influence of abiotic and biotic factors on speciation, the genetic causes of ecological specialization and the evolution of unusual reproductive characters. However, the phylogenetic relationships in the nannoptera species group and its position within the virilis‐repleta phylogeny have not been thoroughly investigated. Using a multilocus data set of gene coding regions of eight nuclear and three mitochondrial genes, we found that the four described nannoptera group species diverged rapidly, with very short internodes between divergence events. Phylogenetic analysis of repleta group lineages revealed that D. inca and D. canalinea are sister to all other repleta group species, whereas the annulimana species D. aracataca and D. pseudotalamancana are sister to the nannoptera and bromeliae species groups. Our divergence time estimates suggest that the nannoptera species group radiated following important geological events in Central America. Our results indicate that a single evolutionary transition to asymmetric genitalia and to unusual sperm storage may have occurred during evolution of the nannoptera group.     

Biological Invasions in the Amazonian Tropical Rain Forest: The Case of Drosophilidae (Insecta,Diptera) in Ecuador,South America

There have been few reports of invasions in continental rain forests, especially for exotic animals. This study provides original data concerning the potential of exotic drosophilid species to colonize the Amazonian tropical rain forest. To investigate if the structure of drosophilid assemblages differed in response to anthropogenic disturbance, we performed a taxonomic survey at six sites within the Yasuni National Park in Ecuadorian Amazonia along a disturbance gradient from pristine to clearcut artificial forest. A total of 7425 individuals from 34 species were collected of which seven species were exotic. There was significant variation in the assemblage composition along this disturbance gradient; 31 percent of which was explained by the presence of exotic species, particularly at the most disturbed sites, through nonmetric multidimensional scaling and SIMPER analyses. These results confirm the susceptibility of continental rain forests to invasion by exotic species. There is an urgent need to develop and implement monitoring systems, for example, based on drosophilid assemblage surveys, to detect exotic invasions in continental tropical forests.     

Field collections reveal that São Tomé is the Afrotropical island with the highest diversity of drosophilid flies (Diptera: Drosophilidae)

Summary

The Drosophilid fauna has been less investigated in the Atlantic Afrotropical islands than in the Indian Ocean. Located about 250 km from the continent, the volcanic island of São Tomé has been colonized mostly by natural means, probably by the wind, since the emergence of the island about 15 million years ago, and presumably also by anthropogenic transportation of invasive and domestic species. To date, 37 different Drosophilid species have been mentioned from São Tomé. The present work extends this list to 80 species. The genera Zygothrica, Phorticella and Hypselothyrea are newly recorded from the island. Among these 80 species, only 12 are putatively introduced by human activities, suggesting the preponderance of natural arrivals. Compared to other islands, São Tomé harbours a high diversity of drosophilids. At least 14 species are supposed to be endemic. Future molecular comparisons between the island flies and their continental relatives will probably help to identify other endemic species. The high diversity observed in São Tomé is certainly due to the large size of the island, and to the presence of vast natural altitudinal forests offering a variety of possible habitats. Further collections are likely to lead to an increase of the species list. From now, São Tomé island appears as an excellent laboratory for studying the ecology and evolution of the Drosophila model.