Cell surface proteoglycan of mammary epithelial cells. Protease releases a heparan sulfate-rich ectodomain from a putative membrane-anchored domain

Heparan sulfate-rich proteoglycan is present on the surface of NMuMG mouse mammary epithelial cells. All of this cell surface fraction is lipophilic, assessed by intercalation into lipid vesicles, and requires proteolytic cleavage to be released from the cell surface. No proteoglycan is competitively displaced by heparin. The cell surface lipophilic proteoglycan constitutes 52-55% of the total cellular proteoglycan while the remaining proteoglycan is apparently intracellular, comprising a nonlipophilic fraction (35%) and a small (10-13%) lipophilic fraction. Trypsin or chymotrypsin cleaves a labile site between the region of the cell surface proteoglycan bearing the glycosaminoglycan chains and the cell-associated portion of the core protein, producing a proteoglycan that is nonlipophilic, has an increased bouyant density, and is smaller than the parent molecule. We refer to this proteoglycan as the ectodomain of the cell surface proteoglycan. The correlation between its cell surface location and lipophilic properties suggests that a hydrophobic domain of its core protein may anchor this proteoglycan in the plasma membrane. In vivo, the proteoglycan may be cleaved from this putative anchor, generating nonlipophilic proteoglycan present as a matrix component, or it may remain a membrane component, anchoring the cell directly to the extracellular matrix.     

Heparan sulfate-mediated binding of epithelial cell surface proteoglycan to thrombospondin

Purified NMuMG mouse mammary epithelial cell surface proteoglycan (PG), a membrane-intercalated core protein bearing both heparan sulfate and chondroitin sulfate glycosaminoglycan (GAG) chains, binds to a thrombospondin (TSP) affinity column and is eluted by a salt gradient. Double immunofluorescence microscopy demonstrates extensive co-localization of bound exogenous TSP and cells bearing exposed cell surface PG at their apical surface. The binding, as assayed by both methods, is heparitinase-sensitive, but not chondroitinase-sensitive. Alkali-released heparan sulfate chains bind to a TSP affinity column, similarly to native PG, whereas the chrondroitin sulfate chains do not. Core protein does not bind to TSP. These results indicate that NMuMG cells bind TSP via their surface PG and that the binding is mediated by the heparan sulfate chains.     

Role of FGFs in skeletal muscle and limb development

Fibroblast growth factors (FGFs) are a family of nine proteins that bind to three distinct types of cell surface molecules: (i) FGF receptor tyrosine kinases (FGFR-1 through FGFR-4); (ii) a cysteine-rich FGF receptor (CFR); and (iii) heparan sulfate proteoglycans (HSPGs). Signaling by FGFs requires participation of at least two of these receptors: the FGFRs and HSPGs form a signaling complex. The length and sulfation pattern of the heparan sulfate chain determines both the activity of the signaling complex and, in part, the ligand specificity for FGFR-1. Thus, the heparan sulfate proteoglycans are likely to play an essential role in signaling. We have recently identified a role for FGF in limb bud development in vivo. In the chick limb bud, ectopic expression of the 18 kDa form of FGF-2 or FGF-2 fused to an artificial signal peptide at its amino terminus causes skeletal duplications. These data, and the observations that FGF-2 is localized to the subjacent mesoderm and the apical ectodermal ridge in the early developing limb, suggest that FGF-2 plays an important role in limb outgrowth. We propose that FGF-2 is an apical ectodermal ridgederived factor that participates in limb outgrowth and patterning. © 1994 Wiley-Liss, Inc.     

The appearance of an extracellular arylsulfatase during morphogenesis of the sea urchin Strongylocentrotus purpuratus

An increase in arylsulfatase activity occurs after hatching in embryos of the sea urchin Strongylocentrotus pupuratus. The bulk of this increase can be attributed to the accumulation of an extracellular activity, since it can be removed by an embryo dissociation medium or upon protease treatment of intact embryos. Also, intact embryos can hydrolyze exogenous substrate, displaying activity equivalent to that which can be removed by the dissociation or protease treatment. The data indicate that the activity appears as a newly secreted molecule ionically coupled to a membrane site or to other components in the extracellular matrix. The majority of the activity is a single component of apparently large molecular size (analyzed on polyacrylamide gel electrophoresis), consistent with the suggestion that it may be complexed with other extracellular components. A morphogenetic role for this enzyme is suggested by the appearance of the extracellular sulfatase temporally coincident with the requirement of sulfated proteoglycans and glycoproteins for cell movement and shape changes.     

Fascioloides magna (Bassi, 1875) in feral swine from southern Texas.

Between 1971 and 1975, Fascioloides magna was found in 46 of 67 (69%) feral swine (Sus scrofa) in southern Texas. Flukes were recovered from swine in areas where F. magna commonly has been recovered from white-tailed deer and cattle. One to 12 flukes were recovered from each infected animal. Their presence was indicated by black hematin pigment on the liver and various other internal organs. Eggs were not detected in the gallbladder or feces of infected animals although mature flukes and eggs were recovered in the livers suggesting that, like cattle, feral swine can be infected but are aberrant hosts for the parasite and do not disseminate eggs.     

Syndecan-1-mediated cell spreading requires signaling by alphavbeta3 integrins in human breast carcinoma cells

Syndecans are cell surface heparan sulfate proteoglycans with regulatory roles in cell adhesion, proliferation, and differentiation [Annu. Rev. Biochem. 68 (1999) 729]. While the syndecan heparan sulfate chains are essential for matrix binding, less is known about the signaling role of their core proteins. To mimic syndecan-specific adhesion, MDA-MB-231 mammary carcinoma cells were plated on antibodies against syndecan-4 or syndecan-1. While cells adherent via syndecan-4 spread, cells adherent via syndecan-1 do not. However, cells adherent via syndecan-1 can be induced to spread by Mn(2+), suggesting that activation of a beta(1) or beta(3) integrin partner is required. Surprisingly, pretreatment of cells with a function-activating beta(1) antibody does not induce spreading, whereas function-blocking beta(1) integrin antibodies do, suggesting involvement of a beta(1)-to-beta(3) integrin cross-talk. Indeed, blockade of beta(1) integrin activation induces alpha(v)beta(3) integrin activation detectable by soluble fibrinogen binding. Spreading in response to syndecan-1 is independent of integrin-ligand binding. Furthermore, competition with soluble murine syndecan-1 ectodomain, which does not disrupt cell adhesion, nonetheless blocks the spreading mechanism. These data suggest that the ectodomain of the syndecan-1 core protein directly participates in the formation of a signaling complex that signals in cooperation with alpha(v)beta(3) integrins; signaling via this complex is negatively regulated by beta(1) integrins.     

IL-11 and IL-11Rα immunolocalisation at primate implantation sites supports a role for IL-11 in placentation and fetal development

Embryo implantation, endometrial stromal cell decidualization and formation of a functional placenta are critical processes in the establishment and maintenance of pregnancy. Interleukin (IL)-11 signalling is essential for adequate decidualization in the mouse uterus and IL-11 promotes decidualization in the human. IL-11 action is mediated via binding to the specific IL-11 receptor α (IL-11Rα). The present study examined immunoreactive IL-11 and IL-11Rα in cycling rhesus monkey endometrium, at implantation sites in cynomolgus and rhesus monkeys and in human first trimester decidua and defined distinct spatial and temporal patterns. In cycling rhesus monkey endometrium, IL-11 and IL-11Rα increased in both basalis and functionalis regions during the secretory compared with the proliferative phase, with changing cellular locations in luminal and glandular epithelium and stroma. The patterns were similar overall to those previously described in human endometrium. Differences were seen in immunostaining during implantation in cynomologus and rhesus monkey. In the cynomolgus, very little staining for IL-11 or IL-11Rα was seen in syncytio- and cyto-trophoblast cells in the villi between days 12 and 150 of pregnancy although there was moderate staining in cytotrophoblast in the shell between days 12 and 17 and in subpopulations of cytotrophoblast cells invading the arteries at day 17. By contrast in the rhesus monkey between days 24 and 35 of pregnancy and in human first trimester placenta, cyto- and syncytio-trophoblast in the villi but not cytotrophoblast in the shell were positively stained. The most intense staining for both IL-11 and IL-11Rα was present within the decidua in the maternal component of implantation sites in all three primates but moderate staining was also present in maternal vascular smooth muscle and glands perivascular cells and epithelial plaques. These results are consistent with a role for IL-11 both during decidualization and placentation in primates.     

Accelerated hand bone mineral density loss is associated with progressive joint damage in hands and feet in recent-onset rheumatoid arthritis

Introduction

To investigate whether accelerated hand bone mineral density (BMD) loss is associated with progressive joint damage in hands and feet in the first year of rheumatoid arthritis (RA) and whether it is an independent predictor of subsequent progressive total joint damage after 4 years.

Methods

In 256 recent-onset RA patients, baseline and 1-year hand BMD was measured in metacarpals 2-4 by digital X-ray radiogrammetry. Joint damage in hands and feet were scored in random order according to the Sharp-van der Heijde method at baseline and yearly up to 4 years.

Results

68% of the patients had accelerated hand BMD loss (>-0.003 g/cm²) in the first year of RA. Hand BMD loss was associated with progressive joint damage after 1 year both in hands and feet with odds ratios (OR) (95% confidence intervals [CI]) of 5.3 (1.3-20.9) and 3.1 (1.0-9.7). In univariate analysis, hand BMD loss in the first year was a predictor of subsequent progressive total joint damage after 4 years with an OR (95% CI) of 3.1 (1.3-7.6). Multivariate analysis showed that only progressive joint damage in the first year and anti-citrullinated protein antibody positivity were independent predictors of long-term progressive joint damage.

Conclusions

In the first year of RA, accelerated hand BMD loss is associated with progressive joint damage in both hands and feet. Hand BMD loss in the first year of recent-onset RA predicts subsequent progressive total joint damage, however not independent of progressive joint damage in the first year.     

An overview of malaria transmission from the perspective of Amazon Anopheles vectors

In the Americas, areas with a high risk of malaria transmission are mainly located in the Amazon Forest, which extends across nine countries. One keystone step to understanding the Plasmodium life cycle in Anopheles species from the Amazon Region is to obtain experimentally infected mosquito vectors. Several attempts to colonise Ano- pheles species have been conducted, but with only short-lived success or no success at all. In this review, we review the literature on malaria transmission from the perspective of its Amazon vectors. Currently, it is possible to develop experimental Plasmodium vivax infection of the colonised and field-captured vectors in laboratories located close to Amazonian endemic areas. We are also reviewing studies related to the immune response to P. vivax infection of Anopheles aquasalis, a coastal mosquito species. Finally, we discuss the importance of the modulation of Plasmodium infection by the vector microbiota and also consider the anopheline genomes. The establishment of experimental mosquito infections with Plasmodium falciparum, Plasmodium yoelii and Plasmodium berghei parasites that could provide interesting models for studying malaria in the Amazonian scenario is important. Understanding the molecular mechanisms involved in the development of the parasites in New World vectors is crucial in order to better determine the interaction process and vectorial competence.     

Biocontrol evaluation of extracts and a major component,clusianone, from Clusia fluminensis Planch. & Triana against Aedes aegypti

Studies evaluated the effects of hexanic extracts from the fruits and flowers ofClusia fluminensis and the main component of the flower extract, a purified benzophenone (clusianone), against Aedes aegypti. The treatment of larvae with the crude fruit or flower extracts from C. fluminensis did not affect the survival ofAe. aegypti (50 mg/L), however, the flower extracts significantly delayed development of Ae. aegypti. In contrast, the clusianone (50 mg/L) isolate from the flower extract, representing 54.85% of this sample composition, showed a highly significant inhibition of survival, killing 93.3% of the larvae and completely blocking development of Ae. aegypti. The results showed, for the first time, high activity of clusianone against Ae. aegypti that both killed and inhibited mosquito development. Therefore, clusianone has potential for development as a biopesticide for controlling insect vectors of tropical diseases. Future work will elucidate the mode of action of clusianone isolated from C. fluminensis.