Regulation of steroidogenesis by atrial natriuretic peptide (ANP) in the rat testis: differential involvement of GC-A and C receptors

Previous studies have established a stimulatory effect of natriuretic peptides (NP) on testosterone production in mouse Leydig cells as intense as that of LH. Chronic administration of ANP in mice, on the other side, reduced testosterone levels. So, the understanding of the role of ANP on testicular steroidogenesis has been impaired by discrepant findings. The aim of the present study was to clarify the physiological role of ANP in the rat testis steroidogenesis using a model that preserves the interactions between testis cells and a medium devoid of any circulating factors that could interfere with testosterone production. First, ANP was immunolocalized in the interstitial compartment of the rat testis, mainly in Leydig cells. We also determined the presence of ANP and both GC-A (guanylyl cyclase A) and C receptors by real-time PCR in testis. Perfusion in vitro of testis with ANP (1 and 3x10(-7)M) stimulated testosterone production in a time- and dose-dependent manner. On the other side, testosterone secretion induced by LH was blunted by ANP. Similar effect was obtained using the specific C receptor ligand, cANF, indicating the involvement of C receptor in such response. In conclusion, ANP stimulated testosterone production in the rat testis perfused in vitro but decreased testosterone production LH-induced, effect that seems to involve C receptor. To this extent, our results suggest the existence of a local and complex peptidergic system in the rat testis, involving ANP and its receptors that could importantly modulate the androgen biosynthesis.     

Enantiodiscrimination of bilirubin-IXalpha enantiomers in biomembrane models: has chirality a role in bilirubin toxicity?

Simple biomembrane models, namely micellar aggregates formed by enantiopure sodium N-acylprolinates, are able to convert the racemic mixture of bilirubin-IXα into an enantiomerically enriched mixture, thus suggesting a possible role of chirality in bilirubin toxicity due to the perturbation of neuron membrane dynamics. The length of alkyl chain does not influence the extent of equilibrium displacement, however, it affects the conformation of bilirubin, thus confirming the role of lipid structure in the membrane/bilirubin interaction, and suggesting a non-superficial main site of association.     

Src homology 2-containing inositol 5-phosphatase 1 binds to the multifunctional docking site of c-Met and potentiates hepatocyte growth factor-induced branching tubulogenesis

Hepatocyte growth factor (HGF)/scatter factor is a multifunctional cytokine that induces mitogenesis, motility, and morphogenesis in epithelial, endothelial, and neuronal cells. The receptor for HGF/scatter factor was identified as c-Met tyrosine kinase, and activation of the receptor induces multiple signaling cascades. To gain further insight into c-Met-mediated multiple events at a molecular level, we isolated several signaling molecules including a novel binding partner of c-Met, SH2 domain-containing inositol 5-phosphatase 1 (SHIP-1). Western blot analysis revealed that SHIP-1 is expressed in the epithelial cell line, Madin-Darby canine kidney (MDCK) cells. SHIP-1 binds at phosphotyrosine 1356 at the multifunctional docking site. Because a number of signaling molecules such as Grb2, phosphatidylinositol 3-kinase, and Gab1 bind to the multifunctional docking site, we further performed an in vitro competition study using glutathione S-transferase- or His-tagged signaling molecules with c-Met tyrosine kinase. Our binding study revealed that SHIP-1, Grb2, and Gab1 bound preferentially over phosphatidylinositol 3-kinase. Surprisingly, MDCK cells that overexpress SHIP-1 demonstrated branching tubulogenesis within 2 days after HGF treatment, whereas wild-type MDCK cells showed tubulogenesis only after 6 days following treatment without altering cell scattering or cell growth potency. Furthermore, overexpression of a mutant SHIP-1 lacking catalytic activity impaired HGF-mediated branching tubulogenesis.     

Atypical glandular cells of undetermined significance. Cytologic predictive value for glandular involvement in high grade squamous intraepithelial lesions

OBJECTIVE: To verify the cytologic predictive value of a diagnosis of atypical glandular cells of undetermined significance (AGUS) in high grade squamous intraepithelial lesions (HSIL) cases. STUDY DESIGN: In a retrospective study, 98 cases of HSIL were reviewed. All patients were referred for colposcopy and directed biopsy to confirm the cytologic diagnoses. Loop excision of the transformation zone was performed to treat clinical lesions. Sensitivity, specificity, positive and negative predictive value were evaluated. Kappa statistics and logistic regression analysis were used to evaluate the findings statistically. RESULTS: By logistic regression analysis, we found that the chance of finding squamous intraepithelial lesions involving glands in AGUS smears was 5.32 times higher than in those with no AGUS. It was 5.74 times higher in cervical intraepithelial neoplasia (CIN) 3 lesions than in CIN 2. CONCLUSION: The cytologic predictive value for HSIL involving glands is statistically significant when specific and objective criteria are used for the AGUS diagnosis.     

STING Contacts: a web-based application for identification and analysis of amino acid contacts within protein structure and across protein interfaces

Amino acid contacts in terms of atomic interactions are essential factors to be considered in the analysis of the structure of a protein and its complexes. Consequently, molecular biologists do require specific tools for the identification and visualization of all such contacts. Graphical contacts (GC) and interface forming residue graphical contacts (IFRgc) presented here, calculate atomic contacts among amino acids based on a table of predefined pairs of the atom types and their distances, and then display them using number of different forms. The inventory of currently listed contact types by GC and IFRgc include hydrogen bonds (in nine different flavors), hydrophobic interactions, charge-charge interactions, aromatic stacking and disulfide bonds. Such extensive catalog of the interactions, representing the forces that govern protein folding, stability and binding, is the key feature of these two applications. GC and IFRgc are part of STING Millennium Suite. AVAILABILITY: http://sms.cbi.cnptia.embrapa.br/SMS, http://trantor.bioc.columbia.edu/SMS, http://mirrors.rcsb.org//SMS, http://www.es.embnet.org/SMS and http://www.ar.embnet.org/SMS (Options: Graphical Contacts and IFR Graphical Contacts).     

TRA-1/GLI controls development of somatic gonadal precursors in C. elegans

TRA-1/GLI is best known as a master regulator of sex determination in the nematode C. elegans, but its fly and vertebrate homologs (e.g. Ci, GLI) regulate embryonic patterning and cell proliferation. In this paper, we show that TRA-1/GLI controls development of the two somatic gonadal precursors (SGPs) in both XX and XO animals, in addition to its role in sex determination. Normally, SGPs reside at the poles of the gonadal primordium and divide according to intrinsic gonadal axes. In tra-1-null mutants, however, SGPs assume non-polar positions and the polarity of one SGP is reversed. Consistent with its SGP function, TRA-1 protein is present in SGPs during embryogenesis and early larval development. Previous studies have shown that the ehn-3 gene also affects SGP positions, and we report here that tra-1 and ehn-3 interact genetically. Whereas SGPs in tra-1 and ehn-3 single mutants are largely normal and generate many descendants, those in tra-1; ehn-3 double mutants do not mature or divide. Furthermore, tra-1 is a dominant enhancer of the ehn-3 gonadal defect, which includes the enhancement of a weak sexual transformation in the gonad. We cloned ehn-3, and found that it encodes a C2H2 zinc-finger protein. A rescuing EHN-3::GFP reporter is predominantly nuclear and expressed specifically in SGPs. The EHN-3 protein is therefore likely to regulate gene expression. We propose that TRA-1/GLI and EHN-3 have overlapping roles in regulation of multiple steps of SGP development. We speculate that regulation of SGP development may be an evolutionarily ancient role of TRA-1/GLI in nematode development.     

In vitro protective effect of Rhodiola rosea extract against hypochlorous acid-induced oxidative damage in human erythrocytes

Rhodiola rosea L. (Crassulaceae) is a plant living at high altitudes in Europe and Asia. Its roots have long been used in the traditional medical system of these geographical areas to increase the organism resistance to physical stress; today, it has become an important component of many dietary supplements. In this study we investigate the antioxidant capacity of the R. rosea aqueous extract evaluating its ability to counteract some of the main damages induced by hypochlorous acid (HOCl), a powerful oxidant generated by activated phagocytes, to human erythrocytes. Ascorbic acid was used as a reference substance because of its physiological HOCl-scavenging ability. Our study demonstrates that R. rosea is able to significantly protect, in a dose-dependent manner, human RBC from glutathione (GSH) depletion, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) inactivation and hemolysis induced by the oxidant. Furthermore, we demonstrate that R. rosea aqueous extract acts from the inside of the erythrocyte suggesting a probable involving of cell components. The protection on GSH afforded by the R. rosea extract with respect to ascorbic acid, occurred also if added 2 or 5 min. later than the oxidant, suggesting a more rapid or powerful effect.