Molecular pathogenesis of interstitial cystitis/bladder pain syndrome based on gene expression.

Interstitial cystitis/painful bladder syndrome (IC/PBS) is a chronic bladder inflammation that leads to chronic bladder pain and urinary urgency and frequency. The presentation of IC/PBS is heterogeneous, and it is classified as ulcerative IC/PBS and nonulcerative IC/PBS. The main cause of IC/PBS is thought to be a persistent inflammatory condition in the bladder, though the actual pathophysiology has not been identified yet. Although the underlying pathophysiology of IC/PBS is not completely understood, several theories for the etiology of this syndrome have been suggested, including deficiency of the glycosaminoglycan covering urothelium surface that results in leaky urothelium infection, immunological etiology, activated mast cells, neural changes, and inflammation. In addition, there are no gold standards for the detection of this disorder to date. So, determination of gene expression and its role in different signaling pathways in the pathogenesis of this heterogeneous disorder contribute to the more efficient cognition of the pathophysiology of this disease and to the design of effective treatments and molecular diagnostic methods for IC/PBS.

A Novel Physiological Glycosaminoglycan-Deficient Splice Variant of Neuropilin-1 Is Anti-Tumorigenic In Vitro and In Vivo.

Neuropilin-1 (NRP1) is a transmembrane protein acting as a co-receptor for several growth factors and interacting with other proteins such as integrins and plexins/semaphorins. It is involved in axonal development, angiogenesis and cancer progression. Its primary mRNA is subjected to alternative splicing mechanisms generating different isoforms, some of which lack the transmembrane domain and display antagonist properties to NRP1 full size (FS). NRP1 is further post-translationally modified by the addition of glycosaminoglycans (GAG) side chains through an O-glycosylation site at serine612. Here, we characterized a novel splice variant which has never been investigated, NRP1-Δ7, differing from the NRP1-FS by a deletion of 7 amino acids occurring two residues downstream of the O-glycosylation site. This short sequence contains two aspartic residues critical for efficient glycosylation. As expected, the high molecular weight products appearing as a smear in SDS-PAGE and reflecting the presence of GAG in NRP1-FS were undetectable in the NRP1-Δ7 protein. NRP1-Δ7 mRNA was found expressed at an appreciable level, between 10 and 30% of the total NRP1, by various cells lines and tissues from human and murine origin. To investigate the biological properties of this isoform, we generated prostatic (PC3) and breast (MDA-MB-231) cancer cells able to express recombinant NRP1-FS or NRP1-Δ7 in a doxycycline-inducible manner. Cells with increased expression of NRP1-Δ7 were characterized in vitro by a significant reduction of proliferation, migration and anchorage-independent growth, while NRP1-FS had the expected opposite "pro-tumoral" effects. Upon VEGF-A165 treatment, a lower internalization rate was observed for NRP1-Δ7 than for NRP1-FS. Finally, we showed that NRP1-Δ7 inhibited growth of prostatic tumors and their vascularization in vivo. This report identifies NRP1-Δ7 as a splice variant displaying anti-tumorigenic properties in vitro and in vivo, emphasizing the need to consider this isoform in future studies.

The Vaccinia Virus H3 Envelope Protein, a Major Target of Neutralizing Antibodies, Exhibits a Glycosyltransferase Fold and Binds UDP-Glucose.

UNLABELLED: The highly conserved H3 poxvirus protein is a major target of the human antibody response against poxviruses and is likely a key contributor to protection against infection. Here, we present the crystal structure of H3 from vaccinia virus at a 1.9-Å resolution. H3 looks like a glycosyltransferase, a family of enzymes that transfer carbohydrate molecules to a variety of acceptor substrates. Like glycosyltransferases, H3 binds UDP-glucose, as shown by saturation transfer difference (STD) nuclear magnetic resonance (NMR) spectroscopy, and this binding requires Mg(2+) Mutation of the glycosyltransferase-like metal ion binding motif in H3 greatly diminished its binding to UDP-glucose. We found by flow cytometry that H3 binds to the surface of human cells but does not bind well to cells that are deficient in surface glycosaminoglycans. STD NMR experiments using a heparin sulfate decasaccharide confirmed that H3 binds heparin sulfate. We propose that a surface of H3 with an excess positive charge may be the binding site for heparin. Heparin binding and glycosyltransferase activity may be involved in the function of H3 in the poxvirus life cycle. IMPORTANCE: Poxviruses are under intense research because of bioterrorism concerns, zoonotic infections, and the side effects of existing smallpox vaccines. The smallpox vaccine using vaccinia virus has been highly successful, but it is still unclear why the vaccine is so effective. Studying the antigens that the immune system recognizes may allow a better understanding of how the vaccine elicits immunity and how improved vaccines can be developed. Poxvirus protein H3 is a major target of the immune system. The H3 crystal structure shows that it has a glycosyltransferase protein fold. We demonstrate that H3 binds the sugar nucleotide UDP-glucose, as do glycosyltransferases. Our experiments also reveal that H3 binds cell surface molecules that are involved in the attachment of poxviruses to cells. These structural and functional studies of H3 will help in designing better vaccines and therapeutics.

Glycosaminoglycan silencing by engineered CXCL12 variants.

We have engineered GPCR (G protein-coupled receptor) knock-out and high GAG-binding affinity into CXCL12α to inhibit CXCL12α-induced cell migration. Compared to wtCXCL12, the mutant CXCL12α (Δ8 L29K V39K) exhibited a 5.6-fold and a 2.2-fold affinity increase for heparin and heparan sulfate, respectively. From NaCl-based heparin displacement chromatography we concluded that more amino acid replacements would lead to altered GAG (glycosaminoglycan) ligand specificity. GAG silencing by this mutant was shown in a murine seeding model of human cancer cells, whereby a greatly reduced number of liver metastases was detected when the animals were treated intravenously with 1mg/kg CXCL12α (Δ8 L29K V39K) before cancer cell application.

Differential dependence on host cell glycosaminoglycans for infection of epithelial cells by high-risk HPV types.

Human papillomavirus (HPV) infection is the leading cause of cervical cancer world-wide. Here, we show that native HPV particles produced in a differentiated epithelium have developed different strategies to infect the host. Using biochemical inhibition assays and glycosaminoglycan (GAG)-negative cells, we show that of the four most common cancer-causing HPV types, HPV18, HPV31, and HPV45 are largely dependent on GAGs to initiate infection. In contrast, HPV16 can bind and enter through a GAG-independent mechanism. Infections of primary human keratinocytes, natural host cells for HPV infections, support our conclusions. Further, this renders the different virus types differentially susceptible to carrageenan, a microbicide targeting virus entry. Our data demonstrates that ordered maturation of papillomavirus particles in a differentiating epithelium may alter the virus entry mechanism. This study should facilitate a better understanding of the attachment and infection by the main oncogenic HPV types, and development of inhibitors of HPV infection.

Characterization of soluble glycoprotein D-mediated herpes simplex virus type 1 infection.

Herpes simplex virus type 1 (HSV-1) entry into permissive cells involves attachment to cell-surface glycosaminoglycans (GAGs) and fusion of the virus envelope with the cell membrane triggered by the binding of glycoprotein D (gD) to cognate receptors. In this study, we characterized the observation that soluble forms of the gD ectodomain (sgD) can mediate entry of gD-deficient HSV-1. We examined the efficiency and receptor specificity of this activity and used sequential incubation protocols to determine the order and stability of the initial interactions required for entry. Surprisingly, virus binding to GAGs did not increase the efficiency of sgD-mediated entry and gD-deficient virus was capable of attaching to GAG-deficient cells in the absence of sgD. These observations suggested a novel binding interaction that may play a role in normal HSV infection.

The glycosaminoglycan-binding domain of decoy receptor 3 is essential for induction of monocyte adhesion.

Decoy receptor 3 (DcR3), a soluble receptor for Fas ligand, LIGHT (homologous to lymphotoxins shows inducible expression and competes with HSV glycoprotein D for herpes virus entry mediator, a receptor expressed by T lymphocytes), and TNF-like molecule 1A, is highly expressed in cancer cells and in tissues affected by autoimmune disease. DcR3.Fc has been shown to stimulate cell adhesion and to modulate cell activation and differentiation by triggering multiple signaling cascades that are independent of its three known ligands. In this study we found that DcR3.Fc-induced cell adhesion was inhibited by heparin and heparan sulfate, and that DcR3.Fc was unable to bind Chinese hamster ovary K1 mutants defective in glycosaminoglycan (GAG) synthesis. Furthermore, the negatively charged, sulfated GAGs of cell surface proteoglycans, but not their core proteins, were identified as the binding sites for DcR3.Fc. A potential GAG-binding site was found in the C-terminal region of DcR3, and the mutation of three basic residues, i.e., K256, R258, and R259, to alanines abolished its ability to trigger cell adhesion. Moreover, a fusion protein comprising the GAG-binding region of DcR3 with an Fc fragment (DcR3_HBD.Fc) has the same effect as DcR3.Fc in activating protein kinase C and inducing cell adhesion. Compared with wild-type THP-1 cells, cell adhesion induced by DcR3.Fc was significantly reduced in both CD44v3 and syndecan-2 knockdown THP-1 cells. Therefore, we propose a model in which DcR3.Fc may bind to and cross-link proteoglycans to induce monocyte adhesion.

Evidence that the cellular ligand for the human NK cell activation receptor NKp30 is not a heparan sulfate glycosaminoglycan.

NKp30 (NCR3, CD337) is a natural cytotoxicity receptor, expressed on subsets of human peripheral blood NK cells, involved in NK cell killing of tumor cells and immature dendritic cells. The cellular ligand for NKp30 has remained elusive, although evidence that membrane-associated heparan sulfate (HS) proteoglycans are involved in the recognition of cellular targets by NKp30 was recently reported. The data presented in this report show conclusively that HS glycosaminoglycans (GAG) are not ligands for NKp30. We show that removing HS completely from the cell surface of human 293-EBNA cells with mammalian heparanase does not affect binding of rNKp30/human IgG1 Fc chimera complexes or binding of multimeric liposome-rNKp30 complexes. Removing HS from 293-EBNA cells, culture-generated DC, MM-170 malignant melanoma cells, or HeLa cells does not affect the NKp30-dependent killing of these cells by NK cells. We show further that the GAG-deficient hamster pgsA-745 cells that lack HS and the GAG-expressing parent CHO-K1 cells are both killed by NK cells, with killing of both cell lines inhibited to the same extent by anti-NKp30 mAb. From these results we conclude that HS GAG are not ligands for NKp30, leaving open the question as to the nature of the cellular ligand for this important NK cell activation receptor.

Spinoculation of heparan sulfate deficient cells enhances HSV-1 entry, but does not abolish the need for essential glycoproteins in viral fusion.

Cell surface heparan sulfate functions as a co-receptor in HSV-1 entry. In order to study its significance in context with specific gD receptors (nectin-1, HVEM, and 3-O-sulfated heparan sulfate) a low speed centrifugation based virus inoculation (spinoculation) method was used. The experiments were performed at 1200 x g using glycosylaminoglycan positive (GAG+) or deficient (GAG-) cells expressing gD receptors. Clearly, spinoculation of GAG- nectin-1 or HVEM cells enhanced significantly viral entry compared to similar but unspun cells. The enhanced entry was due to increased virus deposition at the cell surface and not due to pelleting of the virus. Among the gD receptors, spinoculated GAG- HVEM cells showed restoration of HSV-1 entry compared to unspinoculated GAG+ HVEM cells. In contrast, spinoculated GAG- nectin-1 cells showed less entry than unspinoculated GAG+ nectin-1 cells. GAG- 3-O-sulfotransferase-expressing cells or heparinase treated GAG+ 3-O-sulfated heparan sulfate cells, in contrast, remained resistant to entry even after spinoculation. To investigate further, any potential effects of centrifugation on membrane fusion, a virus-free cell fusion assay was performed. Clearly, spinning had no effects on cell fusion, nor could it replace the need for all four essential glycoproteins. Taken together these results suggest that heparan sulfate plays a role of an attachment receptor, which could be substituted by spinoculation. This effect, however, varies with the gD receptor used, which in turn, could be used as a means for identifying gD receptor usage for entry into a cell type.

Glycoaminoglycan (GAG) deficiency in protective barrier as an underlying, primary cause of ulcerative colitis, Crohn's disease interstitial cystitis and possibly Reiter's syndrome.

Ulcerative colitis, Crohn's disease and interstitial cystitis share many common features, the most important of which is a defect in the glycoaminoglycan (GAG) defensive barrier. This defect allows penetration of toxins causing localized inflammatory response, followed by fibrosis and distant pathological changes, together with a myriad of biochemical and immunological changes. The latter has caused confusion as to etiology of the aforementioned disorders. This hypothesis is somewhat supported by the fact that agents such as glucosamine and pentosan polysulphate (Elmiron) that replace the GAG layer, improve the conditions. The potential for extrapolation of this hypothesis to atherosclerosis and arthropathies exists. There is a great danger in modern medical research that if one misses the wood for the trees, one becomes hopelessly lost in the minutiae of research. At present, it is embarrassing that ulcerative colitis (UC), Crohn's (CR) and interstitial cystitis (IC) are the cause of a great deal of morbidity and occasionally mortality, yet after intensive research, the etiology and effective treatment eludes us. The research in the past has focused extensively on inflammatory response in the mucosal lining, and biochemical, infective and immunological changes in the serum. This has led to a vast array of research pathways that seem at the present time to be totally lost and, might I say, aimless in direction, as a cause for these conditions, that remain amongst the most imperically treated in modern medicine. Another possible syndrome in this class would be Reiter's, which has many features in common with the above. The basic tenet of a GAG deficiency hypothesis is that, as shown in Figure 1A, an intact GAG layer provides, firstly, a mechanical and electrostatic defence against penetration of infective agents, toxins, antigenic protein moieties, etc. and, secondly, the prevention of extravasation of body fluid components. A degraded GAG layer is the start of the disease cascade of the above group of illnesses.

Macular corneal dystrophy: failure to synthesize a mature keratan sulfate proteoglycan.

Corneal specimens obtained during surgery from patients with macular corneal dystrophy and obtained at autopsy from control eyes were incubated in a medium containing radioactive precursors of glycoproteins and proteoglycans. Biosynthetically radiolabeled material was extracted and characterized by using molecular sieve chromatography and specific enzymes. Cells in control corneas synthesized both a chondroitin sulfate proteoglycan and a keratan sulfate proteoglycan similar to those present in monkey and bovine corneas. Cells in macular corneas synthesized a normal chondroitin sulfate proteoglycan but did not synthesize either keratan sulfate or a mature keratan sulfate proteoglycan. Instead, macular corneas synthesized a glycoprotein with unusually large oligosaccharide side chains. This glycoprotein was not detected in normal corneas and is slightly smaller than normal keratan sulfate proteoglycan. The failure to synthesize a mature keratan sulfate proteoglycan may produce corneal opacity and result in blindness. Because of evidence indicating that the corneal keratan sulfate proteoglycan is normally synthesized through a glycoprotein intermediate [Hart, G. W. & Lennarz, W. (1978) J. Biol. Chem. 253-5795-5801], macular corneal dystrophy may be a defect in glycoprotein processing.

Relapsing polychondritis: review of current status and case report,.

This communication has attempted to review the present state of published knowledge on the syndrome of relapsing polychondritis. Basic anatomic, physiologic, and biochemical changes in this disorder are summarized and the role of metabolic and immunologic alterations in the pathogenesis discussed. An additional case of relapsing polychondritis is reported, and the clinical features of this case, plus those of 131 previously reported, are reviewed with discussion of present day therapeutic experience and prognosis.