The ligand-binding profile of HARE: Hyaluronan and chondroitin sulfates A, C, and D bind to overlapping sites distinct from the sites for heparin, acetylated low-density lipoprotein, dermatan sulfate, and CS-E

Abstract The hyaluronic acid receptor for endocytosis (HARE)/ Stabilin-2 is the primary systemic scavenger receptor for hyaluronan (HA), the chondroitin sulfates (CS), dermatan sulfate (DS), and nonglycosaminoglycan (GAG) ligands such as acetylated low-density lipoprotein (AcLDL), pro-collagen propeptides, and advanced glycation end products. We recently discovered that HARE is also a systemic scavenger receptor for heparin (Hep) (Harris EN, Weigel JA, Weigel PH. 2008. The human hyaluronan receptor for endocytosis [HARE/Stabilin-2] is a systemic clearance receptor for heparin. J Biol Chem. 283:17341–17350). Our goal was to map the binding sites of eight different ligands within HARE. We used biotinylated GAGs and radio-iodinated streptavidin or AcLDL to assess the binding activities of ligands directly or indirectly (by competition with unlabeled ligands) in endocytosis assays using stable cell lines expressing the 315 or 190 kDa HA receptor for endocytosis (315- or 190-HARE) isoforms, and ELISA-like assays, with purified recombinant soluble 190-HARE ecto-domain. For example, Hep binding to HARE was competed by DS, CS-E, AcLDL, and dextran sulfate, but not by other CS types, HA, dextran, or heparosan. 125I-AcLDL binding to HARE was partially competed by Hep and dextran sulfate, but not competed by HA. Two ligands, DS and CS-E, competed with both Hep and HA to some degree. Hep and HA binding or endocytosis is mutually inclusive; binding of these two GAGs occurs with functionally separate, noncompetitive, and apparently noninteracting domains. Thus, HARE binds to HA and Hep simultaneously. Although the domain(s) responsible for Hep binding remains unknown, the Link domain was required for HARE binding to HA, CS-A, CS-C, and CS-D. These results enable us to outline, for the first time, a binding activity map for multiple ligands of HARE

The ligand-binding profile of HARE: Hyaluronan and chondroitin sulfates A, C, and D bind to overlapping sites distinct from the sites for heparin, acetylated low-density lipoprotein, dermatan sulfate, and CS-E

Abstract The hyaluronic acid receptor for endocytosis (HARE)/ Stabilin-2 is the primary systemic scavenger receptor for hyaluronan (HA), the chondroitin sulfates (CS), dermatan sulfate (DS), and nonglycosaminoglycan (GAG) ligands such as acetylated low-density lipoprotein (AcLDL), pro-collagen propeptides, and advanced glycation end products. We recently discovered that HARE is also a systemic scavenger receptor for heparin (Hep) (Harris EN, Weigel JA, Weigel PH. 2008. The human hyaluronan receptor for endocytosis [HARE/Stabilin-2] is a systemic clearance receptor for heparin. J Biol Chem. 283:17341–17350). Our goal was to map the binding sites of eight different ligands within HARE. We used biotinylated GAGs and radio-iodinated streptavidin or AcLDL to assess the binding activities of ligands directly or indirectly (by competition with unlabeled ligands) in endocytosis assays using stable cell lines expressing the 315 or 190 kDa HA receptor for endocytosis (315- or 190-HARE) isoforms, and ELISA-like assays, with purified recombinant soluble 190-HARE ecto-domain. For example, Hep binding to HARE was competed by DS, CS-E, AcLDL, and dextran sulfate, but not by other CS types, HA, dextran, or heparosan. 125I-AcLDL binding to HARE was partially competed by Hep and dextran sulfate, but not competed by HA. Two ligands, DS and CS-E, competed with both Hep and HA to some degree. Hep and HA binding or endocytosis is mutually inclusive; binding of these two GAGs occurs with functionally separate, noncompetitive, and apparently noninteracting domains. Thus, HARE binds to HA and Hep simultaneously. Although the domain(s) responsible for Hep binding remains unknown, the Link domain was required for HARE binding to HA, CS-A, CS-C, and CS-D. These results enable us to outline, for the first time, a binding activity map for multiple ligands of HARE

Endocytic Function, Glycosaminoglycan Specificity, and Antibody Sensitivity of the Recombinant Human 190-kDa Hyaluronan Receptor for Endocytosis (HARE)

The human hyaluronan receptor for endocytosis (hHARE) mediates the endocytic clearance of hyaluronan (HA) and chondroitin sulfate from lymph fluid and blood. Two hHARE isoforms (190 and 315 kDa) are present in sinusoidal endothelial cells of liver, spleen, and lymph nodes (Zhou, B., McGary, C. T., Weigel, J. A., Saxena, A., and Weigel, P. H. (2003) Glycobiology 13, 339–349). Here we report the specificity and function of the 190-kDa HARE, expressed without the larger isoform, in Flp-In 293 cell lines (190hHARE cells). Like the native protein, recombinant hHARE contains ~25 kDa of N-linked oligosaccharides, binds HA in a ligand blot assay, cross-reacts with three anti-rat HARE monoclonal antibodies, and is inactivated by reduction. The 190hHARE cell lines mediated rapid, continuous 125I-HA endocytosis and degradation for \u3e1 day. About 30–50% of the total cellular receptors were on the cell surface, and their recycling time for reutilization was ~8.5 min. The average Kd for the binding of HA to the 190-kDa hHARE at 4 °C was 7 nm with 118,000 total HA binding sites per cell. Competition studies at 37 °C indicated that the 190- kDa hHARE binds HA and chondroitin better than dermatan sulfate and chondroitin sulfates A, C, D, and E, but it does not bind to heparin, heparan sulfate, or keratan sulfate. Although competition was observed at 37 °C, none of the glycosaminoglycans tested, except HA, competed for 125I-HA binding by 190hHARE cells at 4 °C. Anti-HARE monoclonal antibodies #30 and #154, which do not inhibit 125I-HA uptake mediated by the 175-kDa rat HARE, partially blocked HA endocytosis by the 190-kDa hHARE. We conclude that the 190-kDa hHARE can function independently of other hHARE isoforms to mediate the endocytosis of multiple glycosaminoglycans. Furthermore, the rat and human small HARE isoforms have different glycosaminoglycan specificities and sensitivities to inhibition by cross-reacting antibodies

The Hyaluronan Receptor for Endocytosis Mediates Hyaluronan-Dependent Signal Transduction via Extracellular Signal-Regulated Kinases

The hyaluronan (HA) receptor for endocytosis (HARE) mediates the endocytotic clearance of HA and other glycosaminoglycans from lymph and blood. Two isoforms of human HARE, 315- and 190-kDa, are highly expressed in sinusoidal endothelial cells of liver, lymph node, and spleen; HARE is also in specialized cells in the eye, heart, brain, and kidney. Here we determined whether HA binding to HARE initiates intracellular signaling in Flp-In 293 cells stably expressing either the 315- and 190-kDa HARE or the 190-kDa HARE alone. HARE was co-immunoprecipitated with extracellular signal-regulated kinase 1 and 2 (ERK1/2), c-Jun N-terminal protein kinase (JNK), and p38 members of the mitogen-activated protein kinase signaling cascade. ERK phosphorylation increased in a dose- and time-dependent manner when HA was added to cells expressing full-length or 190-kDa HARE, but not cells with vector-only or a HARE(ΔLink) construct with greatly decreased (~90%) HA uptake. HA did not induce phosphorylation of JNK or p38. A maximum increase in phospho-ERK1/2 occurred within 30 min at 5 μg/ml HA, and the response was dampened at \u3e20 μg/ml HA. HA binding did not increase the level of HARE-ERK complexes, but did increase HARE phosphorylation. These findings demonstrate a novel functional response, when HARE binds HA, that leads to activation of ERK1/2, important mediators of intracellular signal transduction

The Human Hyaluronan Receptor for Endocytosis (HARE/Stabilin-2) Is a Systemic Clearance Receptor for Heparin

The hyaluronic acid receptor for endocytosis (HARE; also designated Stabilin-2) mediates systemic clearance of hyaluronan and chondroitin sulfates from the vascular and lymphatic circulations. The internalized glycosaminoglycans are degraded in lysosomes, thus completing their normal turnover process. Sinusoidal endothelial cells of human liver, lymph node, and spleen express two HARE isoforms of 315 and 190 kDa. Here we report that the 190- and 315-kDa HARE isoforms, expressed stably either in Flp-In 293 cell lines or as soluble ectodomains, specifically bind heparin (Hep). The Kd for Hep binding to purified 190- and 315-kDa HARE ectodomains was 17.2 ± 4.9 and 23.4 ± 5.3 nm, respectively. Cells expressing HARE readily and specifically internalized 125I-streptavidin-biotin-Hep complexes, which was inhibited \u3e70% by hyperosmolar conditions, confirming that uptake is mediated by the clathrin-coated pit pathway. Internalization of Hep occurred for many hours with an estimated HARE recycling time of ~12 min. Internalized fluorescent streptavidin-biotin-Hep was present in a typical endocytic vesicular pattern and was delivered to lysosomes. We conclude that HARE in the sinusoidal endothelial cells of lymph nodes and liver likely mediates the efficient systemic clearance of Hep and many different Hep-binding protein complexes from the lymphatic and vascular circulations

Socio-economic inequalities in injury incidence in the Netherlands

Background: Interventions to reduce socio-economic inequalities in injury incidence should be tailored to specific priority areas that may be identified by descriptive studies. We aimed to provide an overview of exist

Green growth or ecological commodification: debating the green economy in the Global South

This article examines recent institutional thinking on the green economy and the implications of official understandings and structuration of a green economy for the global South. Assertions about the transformative potential of a green economy by many international actors conceals a complexity of problems, including the degree to which the green economy is still based on old fossil economies and technical fixes, and the processes through which the green economy ideation remains subject to Northern economic and technical dominance. The article places the intellectual roots of the green economy within a broader historical context and suggests some ways the strategic economic and ideological interests of the global North remain key drivers of green-economy thinking. The analysis is substantiated through two illustrative Latin American examples: the Mesoamerican Biological Corridor and green economy initiatives in Brazil. These suggest that, if the green economy is to address global challenges effectively, it must be conceptualized as more than a bolt-on to existing globalizing capitalism and encompass more critical understandings of the complex socio-economic processes through which poverty is produced and reproduced and through which the global environment is being transformed, a critique which also applies to mainstream discourses of sustainable development

What is the real impact of acute kidney injury?

Background: Acute kidney injury (AKI) is a common clinical problem. Studies have documented the incidence of AKI in a variety of populations but to date we do not believe the real incidence of AKI has been accurately documented in a district general hospital setting. The aim here was to describe the detected incidence of AKI in a typical general hospital setting in an unselected population, and describe associated short and long-term outcomes. Methods: A retrospective observational database study from secondary care in East Kent (adult catchment population of 582,300). All adult patients (18 years or over) admitted between 1st February 2009 and 31st July 2009, were included. Patients receiving chronic renal replacement therapy (RRT), maternity and day case admissions were excluded. AKI was defined by the acute kidney injury network (AKIN) criteria. A time dependent risk analysis with logistic regression and Cox regression was used for the analysis of in-hospital mortality and survival. Results: The incidence of AKI in the 6 month period was 15,325 pmp/yr (adults) (69% AKIN1, 18% AKIN2 and 13% AKIN3). In-hospital mortality, length of stay and ITU utilisation all increased with severity of AKI. Patients with AKI had an increase in care on discharge and an increase in hospital readmission within 30 days. Conclusions: This data comes closer to the real incidence and outcomes of AKI managed in-hospital than any study published in the literature to date. Fifteen percent of all admissions sustained an episode of AKI with increased subsequent short and long term morbidity and mortality, even in those with AKIN1. This confers an increased burden and cost to the healthcare economy, which can now be quantified. These results will furnish a baseline for quality improvement projects aimed at early identification, improved management, and where possible prevention, of AKI

First-Time Parents Are Not Well Enough Prepared for the Safety of Their Infant

Background: Unintentional falls and poisonings are major causes of death and disability among infants. Although guidelines are available to prevent these injuries, safety behaviours are not performed by parents, causing unnecessary risks. Little is known about safety behaviours of first-time parents and whether they behave according to these guidelines. Aims/Objectives/Purpose: The objective of this study was to compare safety behaviours of first-time parents with those of non-first-time parents and to determine correlates of unsafe behaviour of parents of infants. We used self-report questionnaires to assess safety behaviours in a cross-sectional study sample. Methods: A total of 1439 parents visiting a preventive youth healthcare centre in the Netherlands were invited to complete a questionnaire with regard to the prevention of falls and poisonings. Parents were categorized into first-time parents and non-first-time parents. Correlates of parents' child safety behaviours were determined using multiple logistic regression analyses. Results/Outcome: Most respondents were mothers (93.2%); 48.2% of families were first-time parents. The mean age of the infants was 7.2 months (SD 1.1; range 4-12), 51.8% were boys, and 34.5% of infants could crawl. First-time parents were more likely not to have a stair gate installed (OR 16.46; 95% CI 12.36-21.93); were more likely to store cleaning products unsafely (OR 4.55; 95% CI 3.59-5.76); and were more likely to store medicines unsafely (OR 2.90; 95% CI 2.31-3.63) than non-first-time parents. First-time parents were more likely to not have a window guard installed (OR 1.52; 95% CI 1.08-2.15) (all P<0.05). Discussion/Conclusion: First-time parents are not well prepared for the safety of their infant, causing unnecessary risks. The various parents' safety behaviours were influenced by different variables, for example, age of the infant, crawling of the infant, mother's educational level, mother's ethnicity, self-efficacy, vulnerability, severity