Abnormalities in oxygen sensing define early and late onset preeclampsia as distinct pathologies

Background

The pathogenesis of preeclampsia, a serious pregnancy disorder, is still elusive and its treatment empirical. Hypoxia Inducible Factor-1 (HIF-1) is crucial for placental development and early detection of aberrant regulatory mechanisms of HIF-1 could impact on the diagnosis and management of preeclampsia. HIF-1α stability is controlled by O₂-sensing enzymes including prolyl hydroxylases (PHDs), Factor Inhibiting HIF (FIH), and E3 ligases Seven In Absentia Homologues (SIAHs). Here we investigated early- (E-PE) and late-onset (L-PE) human preeclamptic placentae and their ability to sense changes in oxygen tension occurring during normal placental development.

Methods and Findings

Expression of PHD2, FIH and SIAHs were significantly down-regulated in E-PE compared to control and L-PE placentae, while HIF-1α levels were increased. PHD3 expression was increased due to decreased FIH levels as demonstrated by siRNA FIH knockdown experiments in trophoblastic JEG-3 cells. E-PE tissues had markedly diminished HIF-1α hydroxylation at proline residues 402 and 564 as assessed with monoclonal antibodies raised against hydroxylated HIF-1α P402 or P564, suggesting regulation by PHD2 and not PHD3. Culturing villous explants under varying oxygen tensions revealed that E-PE, but not L-PE, placentae were unable to regulate HIF-1α levels because PHD2, FIH and SIAHs did not sense a hypoxic environment.

Conclusion

Disruption of oxygen sensing in E-PE vs. L-PE and control placentae is the first molecular evidence of the existence of two distinct preeclamptic diseases and the unique molecular O₂-sensing signature of E-PE placentae may be of diagnostic value when assessing high risk pregnancies and their severity.     

Expression of cyclo-oxygenase-2 in macrophages associated with cutaneous melanoma at different stages of progression

The biological significance of the almost constant presence of macrophages in the tumoral microenvironment is an issue debated by several authors. The major difficulty in understanding the role played by tumor-associated macrophages (TAMs) in tumor progression is due to the contrasting effects of TAMs found in different studies. In addition, there is a limited information on which of the many biological activities expressed by TAMs are critical in inducing stimulatory or inhibitory effect on tumor growth. The aim of our study was: (a) to explore to what extent cyclo-oxygenase-2 (COX-2) in TAMs associated with human melanoma is expressed at different stages of tumor progression; and (b) to explore whether COX-2 expression in TAMs is stimulated by melanoma cells. In order to answer this question, we determined COX-2 positive TAMs associated with cutaneous melanocytic nevi, in situ, invasive and metastatic melanoma. In addition, we investigated whether COX-2 is expressed in peritoneal thioglycollate-elicited macrophages after co-cultivation with murine B16 melanoma cells. We found that COX-2-positive TAMs, as revealed by immunohistochemical analysis, were rare in common nevi and "dysplastic nevi", but present in a high percentage in in situ and thin melanoma. COX-2-positive TAMs were also found in more advanced tumors and metastatic melanoma, although at a significantly lower percentage in these latter. The in vitro protocol revealed that COX-2 was expressed in peritoneal macrophages upon contact with B16 murine melanoma cells, but not with normal murine fibroblasts. On the whole, the results of in vivo and in vitro studies suggest that COX-2 expressed in TAMs appears to act as an effective biomarker of melanoma progression, and melanoma cells themselves might stimulate COX-2 in macrophages.     

To sample or not to sample? That is the question ... for the vegetation scientist

Lájer (2007) raised the problem of using a non-random sample for statistical testing of plant community data. He argued that this violates basic assumptions of the tests, resulting thus in non-significant results. However, a huge part of present-day knowledge of vegetation science is still based on non-random, preferentially collected data of plant communities. I argue that, given the inherent limits of preferential sampling, a change of approach is now necessary, with the adoption of sampling based on random principles seeming the obvious choice. However, a complete transition to random-based sampling designs in vegetation science is limited by the yet undefined nature of plant communities and by the still diffused opinion that plant communities have a discrete nature. Randomly searching for such entities is almost impossible, given their dependence on scale of observation, plot size and shape, and the need for finding well-defined types. I conclude that the only way to solve this conundrum is to consider and study plant communities as operational units. If the limits of the plant communities are defined operationally, they can be investigated using proper sampling techniques and the collected data analyzed using adequate statistical tools.     

Biochemical analysis of the DNA unwinding and strand annealing activities catalyzed by human RECQ1

RecQ helicases play an important role in preserving genomic integrity, and their cellular roles in DNA repair, recombination, and replication have been of considerable interest. Of the five human RecQ helicases identified, three are associated with genetic disorders characterized by an elevated incidence of cancer or premature aging: Werner syndrome, Bloom syndrome, and Rothmund-Thomson syndrome. Although the biochemical properties and protein interactions of the WRN and BLM helicases defective in Werner syndrome and Bloom syndrome, respectively, have been extensively investigated, less information is available concerning the functions of the other human RecQ helicases. We have focused our attention on human RECQ1, a DNA helicase whose cellular functions remain largely uncharacterized. In this work, we have characterized the DNA substrate specificity and optimal cofactor requirements for efficient RECQ1-catalyzed DNA unwinding and determined that RECQ1 has certain properties that are distinct from those of other RecQ helicases. RECQ1 stably bound to a variety of DNA structures, enabling it to unwind a diverse set of DNA substrates. In addition to its DNA binding and helicase activities, RECQ1 catalyzed efficient strand annealing between complementary single-stranded DNA molecules. The ability of RECQ1 to promote strand annealing was modulated by ATP binding, which induced a conformational change in the protein. The enzymatic properties of the RECQ1 helicase and strand annealing activities are discussed in the context of proposed cellular DNA metabolic pathways that are important in the maintenance of genomic stability.     

Identification and phenotypic characterization of a subpopulation of T84 human colon cancer cells, after selection on activated endothelial cells

The extravasation of metastatic cells is regulated by molecular events involving the initial adhesion of tumor cells to the endothelium and subsequently the migration of the cells in the host connective tissue. The differences in metastatic ability could be attributed to properties intrinsic of the various primary tumor types. Thus, the clonal selection of neoplastic cells during cancer progression results in cells better equipped for survival and formation of colonies in secondary sites. A cell line (T84SF) exhibiting an altered phenotypic appearance was selected from a colon cancer cell line (T84) by repetitive plating on TNFalpha-activated human endothelial cells and subsequent selection for adherent cells. Cell growth, motility, chemoinvasive abilities, tyrosine phosphorylation signaling, and the metastasis formation in nude mice of the two cell lines was compared. T84SF cells displayed in vitro an higher proliferation rate and a more invasive behavior compared to the parental cells while formed in vivo a greater number of metastatic colonies in nude mice. As concerns the signaling underlying the phenotypes of the selected cells, we examined the general tyrosine phosphorylation levels in both cell lines. Our results indicate that T84SF have an increased basal tyrosine phosphorylation of several proteins among which src kinase was identified. Treatment of cells with a specific inhibitor of src activity caused a greater in vitro inhibition of proliferation and invasive properties of T84 parental cells with respect to T84SF cells and diminished metastasis formation in vivo. Altogether, these data provide evidences that this new cell line may be valuable for identifying molecular mechanisms involved in the metastatic progression of colon cancer.     

Properties of sesame oil by detailed 1H and 13C NMR assignments before and after ozonation and their correlation with iodine value,peroxide value,and viscosity measurements

Gaseous ozone chemically reacts with unsaturated triglyceride substrates leading to ozonated derivatives with a wide potential applications, ranging from the petrochemical to the pharmaceutical industry. To date, an ultimate understanding of the ozone reactivity during sesame oil ozonation process as well as detailed ¹H and ¹³C NMR assignments are lacking. A practical advantage of NMR is that a single NMR sample measurement can explain many issues, while similar analysis by traditional methods may require several independent and time-consuming measurements. Moreover, significant relationships among NMR spectra and both conventional chemical analysis and viscosity measurements have been found. Eventually, NMR could play an important role for quality attributes of ozonated oil derivatives.     

"Cold spots" in protein cold adaptation: Insights from normalized atomic displacement parameters (B'-factors)

Many analyses published in the last decade suggest that enzymes isolated from cold-adapted organisms are characterized by a higher flexibility of their molecular structure. Recently, it has been argued that all cold-adapted enzymes with catalytic efficiency greater than that of their mesophilic counterparts display local flexibility or rigidity that are likely to cooperate, each acting on specific areas of the enzyme structure. Here we report an analysis of the normalized thermal B-factor distributions in psychrophilic proteins compared with those of their mesophilic and thermophilic counterparts with the aim to detect statistically significant local variations of relative backbone flexibility possibly linked to cold adaptation. We utilized a strategy based mainly on intra-family comparison of local distribution of normalized B-factors. After careful statistical treatment of data, the picture emerging from our results suggests that the distribution of the flexibility in psychrophilic enzymes is locally more heterogeneous than in their respective mesophilic homologues.