1: Biochem Soc Trans. 2006 Jun;34(Pt 3):422-6.


The biological relevance of chemokine-proteoglycan interactions.

Proudfoot AE.

Serono Pharmaceutical Research Institute, Plan-les-Ouates, Geneva, Switzerland. amanda.proudfoot@serono.com

Chemokines exert their biological activity through high-affinity interactions with cell-surface receptors, thereby activating specific signalling pathways, and a second low-affinity interaction with proteoglycans. Proteoglycans consist of a protein core, to which GAG (glycosaminoglycan) chains are attached. The GAGs are long, linear, sulphated and highly charged heterogeneous polysaccharides that are expressed throughout the body in different forms depending on the developmental or pathological state of the organ/organism. Mechanistically, the GAG interaction is thought to facilitate the retention of chemokines on cell surfaces, thereby forming a high local concentration required for cell activation. Recently, we demonstrated that certain chemokines require interactions with GAGs for their in vivo function. Additionally we have shown that chemokines oligomerize on immobilized GAGs, and this ability to form higher order oligomers has also been shown to be essential for the activity of certain chemokines in vivo. We believe that interference with the chemokine-GAG interaction provides a novel anti-inflammatory strategy, exemplified by a variant of RANTES (regulated upon activation, normal T-cell expressed and secreted) that has abrogated GAG binding and oligomerization properties.

Publication Types:
Review

PMID: 16709177 [PubMed - indexed for MEDLINE]

--------------------------------------------------------------------------------

2: Microsc Res Tech. 1999 Feb 15;44(4):304-9.


Molecular self-recognition and adhesion via proteoglycan to proteoglycan interactions as a pathway to multicellularity: atomic force microscopy and color coded bead measurements in sponges.

Misevic GN.

Laboratoire de Chimie Biologique, Universite de Sciences et Technologies de Lille, UMR 111 de CNRS, France. gmisevic@datacomm.ch

During the emergence of multicellular organisms, molecular mechanisms evolved to allow maintenance of anatomical integrity and self-recognition. We propose that carbohydrates from proteoglycans, as the most peripheral cell surface, and matrix molecules might have provided these key adhesion and recognition functions. If so, the Porifera as the simplest metazoans alive today should retain, at least in part, proteoglycan adhesion and recognition mechanisms. Early work on cell adhesion of dissociated marine sponge cells provided important phenomenological evidence for cell sorting. Here is reviewed recent work on molecular mechanisms of cell recognition and adhesion mediated by cell surface proteoglycans purified from three marine sponge species, Microciona prolifera, Halichondria panicea, and Cliona celata. Biochemical characterization of isolated proteoglycans showed that each species expressed a unique type of primordial molecule named glyconectins. These proteoglycans displayed species-specific self-recognition and adhesion in color-coded bead, cell, and blotting assays. The specificity of homophilic proteoglycan to proteoglycan interactions in the Porifera approaches the binding selectivity of the evolutionarily advanced immunoglobulin superfamily system. Such xeno-selectivity may be a new paradigm for the molecular self-recognition, which was a fundamental requirement in the self/non-self discrimination during the emergence of multicellularity and further divergence of species. We have used atomic force microscopy (AFM) technology to directly measure intermolecular binding strength between individual pairs of ligand and receptor molecules in physiological solution. Homophilic glyconectin interactions were investigated by AFM after covalent attachment of the protein core to the sensor tip and to a flat surface, leaving the carbohydrates unmodified. AFM measurements of the binding strength between glyconectins indicated that one pair of molecules could theoretically hold the weight of 1,600 cells in physiological solution. These results provided the first essential and quantitative evidence that proteoglycan-proteoglycan binding can perform the adhesion function that we have assigned to it. Our investigations with purified proteoglycans from the marine sponge M. prolifera (glyconectin 1) using bead and cell adhesion assays have provided evidence that a new molecular mechanism of polyvalent and specific glycan-glycan binding between proteoglycans can mediate cell recognition and adhesion. Partial sequencing of the glycans has revealed two new cell adhesion carbohydrate structures: (3)GlcNAc(3OSO3)beta1-3Fuc and Pyr4,6Galbeta1-4GlcNAcbeta1-3Fuc.

Publication Types:
Research Support, Non-U.S. Gov't
Review

PMID: 10098930 [PubMed - indexed for MEDLINE]

--------------------------------------------------------------------------------

3: Perspect Dev Neurobiol. 1996;3(4):359-71.


Agrin: an extracellular matrix heparan sulfate proteoglycan involved in cell interactions and synaptogenesis.

Cole GJ, Halfter W.

Neurobiotechnology Center, Ohio State University, Columbus 43210, USA.

Recent studies have documented important roles for heparan sulfate proteoglycans in the control of nervous system development. Agrin is an extracellular matrix protein identified and named based on its involvement in the aggregation of acetylcholine receptors (AChRs) during synaptogenesis at the neuromuscular junction. Recent studies have demonstrated that agrin is a large extracellular heparan sulfate proteoglycan, with a molecular mass in excess of 500 kDa and a protein core of 220 kDa. Emerging evidence indicates that agrin's function is not limited to its role in AChR aggregation during synaptogenesis, as the majority of agrin expression occurs in the developing central nervous system, especially in developing axonal tracts. This review examines recent studies suggesting a role for agrin in the regulation of cell-cell interactions, most notably by its ability to interact with the neural cell adhesion molecule. In addition, other potential roles for the heparan sulfate chains of agrin during nervous system development are explored.

Publication Types:
Review

PMID: 9117266 [PubMed - indexed for MEDLINE]

--------------------------------------------------------------------------------

4: Biophys Chem. 1994 May;50(1-2):113-28.


The cartilage proteoglycan aggregate: assembly through combined protein-carbohydrate and protein-protein interactions.

Mörgelin M, Heinegård D, Engel J, Paulsson M.

Department of Medical and Physiological Chemistry, University of Lund, Sweden.

In vitro reassembled aggregates of cartilage proteoglycan (aggrecan) were studied by glycerol spraying/rotary shadowing electron microscopy and compared to the corresponding native (i.e. never dissociated) structures. In both cases a tightly packed central filament structure was observed consisting of the hyaluronate binding region (HABR) of the proteoglycan, link protein (LP) and hyaluronate (HA). This differs from earlier results where a discontinuous central filament structure was seen after spreading proteoglycan aggregates at a water/air interphase. Binding of isolated HABR to HA is random but upon addition of link protein a clustering of the HA-binding proteins is observed, indicating a cooperativity. In a fully saturated aggregate the HA is covered by a continuous protein shell consisting of HABR and LP. When added in amounts below saturation HABR and LP bind to the HA in clusters which are interrupted by free strands of HA. The proteoglycan aggregate is thus an example for a structure where a polysaccharide forms a template for a supramolecular assembly largely stabilized by protein-protein interactions.

Publication Types:
Comparative Study
Research Support, Non-U.S. Gov't
Review

PMID: 8011926 [PubMed - indexed for MEDLINE]

--------------------------------------------------------------------------------

5: Biochem Soc Trans. 1991 Nov;19(4):877-81.


Proteoglycan: collagen interactions and corneal ultrastructure.

Scott JE.

Chemical Morphology, Manchester University, U.K.

Publication Types:
Review

PMID: 1794577 [PubMed - indexed for MEDLINE]

--------------------------------------------------------------------------------

6: Int J Biol Macromol. 1991 Jun;13(3):157-61.


Proteoglycan: collagen interactions in connective tissues. Ultrastructural, biochemical, functional and evolutionary aspects.

Scott JE.

Chemical Morphology, Cell and Structural Biology, Manchester University, UK.

Electron histochemical investigations of mammalian and echinoderm tissues, using cupromeronic blue to stain proteoglycans (PGs) specifically in critical electrolyte concentration methods, showed that collagen fibrils are associated with keratan sulphate and chondroitin (dermatan) sulphate ('tadpole') PGs at the a, c, d and e bands on the fibril surface, giving rise to the 'one proteoglycan: one binding site' hypothesis. Intra-fibrillar PGs have been observed, distributed in a regular way which suggests that collagen fibrils are aggregates of 'protofibrils', some of which carry PGs at their surfaces. A scheme for remodelling of collagen fibrils, based on recycling of these protofibrils, is outlined. The choice of which tadpole PG to use to carry out a given function is decided to a considerable extent by the availability of oxygen to the relevant tissue element.

Publication Types:
Review

PMID: 1911556 [PubMed - indexed for MEDLINE]

--------------------------------------------------------------------------------

7: Biochem J. 1988 Jun 1;252(2):313-23.


Proteoglycan-fibrillar collagen interactions.

Scott JE.

Manchester University, U.K.

Publication Types:
Review

PMID: 3046606 [PubMed - indexed for MEDLINE]

--------------------------------------------------------------------------------

8: Ciba Found Symp. 1984;108:25-43.


Laminin, proteoglycan, nidogen and collagen IV: structural models and molecular interactions.

Timpl R, Fujiwara S, Dziadek M, Aumailley M, Weber S, Engel J.

Major components of basement membranes, including collagen IV, laminin, heparan sulphate proteoglycan and nidogen, were isolated from the matrix of the EHS sarcoma. The purified components were analysed for their domain structure and for the participation of distinct domains in molecular interactions and cell binding. Collagen IV consists of four domains which have triple helical or non-collagenous structures. Self-assembly of the protein into a network-like organization occurs by specific interactions between N-terminal triple helical segments and between the C-terminal globules. Cell binding requires a central triple helical segment. Laminin has the shape of an asymmetrical cross; different globular domains within this structure mediate binding to proteoglycan and to cells. The proteoglycan consists of four heparan sulphate chains attached to a small protein core. These chains have the potential to bind laminin, fibronectin and collagen IV. Nidogen was isolated in several molecular forms which showed either self-aggregation or binding to laminin.

Publication Types:
Research Support, Non-U.S. Gov't
Review

PMID: 6440757 [PubMed - indexed for MEDLINE]

--------------------------------------------------------------------------------

9: Agents Actions. 1980 Dec;10(6):474-85.


Cell-to-cell interactions in the secretion of enzymes of connective tissue breakdown, collagenase and proteoglycan-degrading neutral proteases. A review.

Vaes G.

Cell and tissue culture techniques provide valuable tools for investigating cell-to-cell interactions leading to the secretion of connective-tissue degrading enzymes, collagenase and proteoglycan-degrading neutral proteases, in inflammatory situations. These interactions, which might constitute a major regulatory mechanism, are reviewed here. Taken together, the available data strongly suggest that fibroblasts and related mesenchymal cells (such as chondrocytes, fibroblast-like or type B synovial lining cells, corneal stromal cells, etc.) could be the main suppliers of collagenase within tissues. These cells can secrete collagenase in response to factors produced by other cells, mainly macrophages and related cells (monocytes, synovial cells - presumably the macrophage like, type A synovial lining cells), possibly also epithelial cells. Lymphocytes are able to modulate factor production by macrophages so that, through the macrophage link the secretory behavior of the fibroblastic cells may be under the control of the immune defense system and serve as an effector of immune reactions leading to connective tissue destruction.

Publication Types:
Research Support, Non-U.S. Gov't
Review

PMID: 6267911 [PubMed - indexed for MEDLINE]