New insights into heparan sulphate biosynthesis from the study of mutant mice

2002 ◽  
Vol 69 ◽  
pp. 47-57 ◽  
Author(s):  
Catherine L. R. Merry ◽  
John T. Gallagher
Keyword(s):  
Growth Factors ◽  
Biosynthetic Pathway ◽  
Heparan Sulphate ◽  
Mutant Mice ◽  
Gene Products ◽  
Multiple Gene ◽  
Adhesion Proteins ◽  
Ligand Interactions

Heparan sulphate (HS) is an essential co-receptor for a number of growth factors, morphogens and adhesion proteins. The biosynthetic modifications involved in the generation of a mature HS chain may determine the strength and outcome of HS–ligand interactions. These modifications are catalysed by a complex family of enzymes, some of which occur as multiple gene products. Various mutant mice have now been generated, which lack the function of isolated components of the HS biosynthetic pathway. In this discussion, we outline the key findings of these studies, and use them to put into context our own work concerning the structure of the HS generated by the Hs2st-/- mice.

Heparin stimulates the proliferation of intestinal epithelial cells in primary culture

1994 ◽  
Vol 107 (2) ◽  
pp. 401-411
Author(s):  
N. Flint ◽  
F.L. Cove ◽  
G.S. Evans
Keyword(s):  
Growth Factors ◽  
Heparan Sulphate ◽  
Primary Cultures ◽  
Cell Types ◽  
Heparin Binding ◽  
Epithelial Proliferation ◽  
Inhibition Of Proliferation ◽  
Trophic Effect ◽  
Heparin Binding Growth Factors

Heparin is a sulphated glycosaminoglycan derived from mast cells and has a number of functions including the inhibition of proliferation in several cell types and interactions with a range of heparin-binding growth factors. We report that heparin is a trophic factor in primary cultures of rat small intestinal epithelium. Heparin elicits a dose-dependent increase in epithelial proliferation and inhibits the growth of associated mesenchyme. The trophic effect of this molecule is not reproduced by other glycosaminoglycans including heparan sulphate but is dependent upon extensive molecular sulphation. Highly sulphated polysaccharides that are structurally unrelated to heparin (e.g. dextran sulphate and pentosan polysulphate) also stimulate epithelial proliferation in primary cultures. Heparin may act by the potentiation of mesenchyme-derived heparin-binding growth factors and these data suggest an in vivo role for mast cell-derived heparin in mucosal wound regeneration.

scholarly journals Surprising Arginine Biosynthesis: a Reappraisal of the Enzymology and Evolution of the Pathway in Microorganisms

2007 ◽  
Vol 71 (1) ◽  
pp. 36-47 ◽  
Author(s):  
Ying Xu ◽  
Bernard Labedan ◽  
Nicolas Glansdorff
Keyword(s):  
Biosynthetic Pathway ◽  
De Novo ◽  
Single Gene ◽  
Metabolic Function ◽  
Gene Products ◽  
Arginine Biosynthesis ◽  
Acetyl Coenzyme A ◽  
Bacterial Phyla ◽  
Acetyl Group ◽  
Acetylglutamate Synthase

SUMMARY Major aspects of the pathway of de novo arginine biosynthesis via acetylated intermediates in microorganisms must be revised in light of recent enzymatic and genomic investigations. The enzyme N-acetylglutamate synthase (NAGS), which used to be considered responsible for the first committed step of the pathway, is present in a limited number of bacterial phyla only and is absent from Archaea. In many Bacteria, shorter proteins related to the Gcn5-related N-acetyltransferase family appear to acetylate l-glutamate; some are clearly similar to the C-terminal, acetyl-coenzyme A (CoA) binding domain of classical NAGS, while others are more distantly related. Short NAGSs can be single gene products, as in Mycobacterium spp. and Thermus spp., or fused to the enzyme catalyzing the last step of the pathway (argininosuccinase), as in members of the Alteromonas-Vibrio group. How these proteins bind glutamate remains to be determined. In some Bacteria, a bifunctional ornithine acetyltransferase (i.e., using both acetylornithine and acetyl-CoA as donors of the acetyl group) accounts for glutamate acetylation. In many Archaea, the enzyme responsible for glutamate acetylation remains elusive, but possible connections with a novel lysine biosynthetic pathway arose recently from genomic investigations. In some Proteobacteria (notably Xanthomonadaceae) and Bacteroidetes, the carbamoylation step of the pathway appears to involve N-acetylornithine or N-succinylornithine rather than ornithine. The product N-acetylcitrulline is deacetylated by an enzyme that is also involved in the provision of ornithine from acetylornithine; this is an important metabolic function, as ornithine itself can become essential as a source of other metabolites. This review insists on the biochemical and evolutionary implications of these findings.

Cell membrane-associated proteoglycans mediate extramedullar myeloid proliferation in granulomatous inflammatory reactions to schistosome eggs

1993 ◽  
Vol 104 (2) ◽  
pp. 477-484
Author(s):  
M. Alvarez-Silva ◽  
L.C. da Silva ◽  
R. Borojevic
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Connective Tissue ◽  
Endogenous Growth ◽  
Cell Lines ◽  
Cell Layer ◽  
Heparan Sulphate ◽  
Myeloid Cells ◽  
Myeloid Cell ◽  
Gm Csf

In chronic murine schistosomiasis, extramedullar myelopoiesis was observed, with proliferation of myeloid cells in liver parenchyma and in periovular granulomas. We have studied the question of whether cells obtained from granulomatous connective tissue may act as myelopoietic stroma, supporting long-term myeloid proliferation. Primary cell lines (GR) were obtained in vitro from periovular granulomas, induced in mouse livers by Schistosoma mansoni infection. These cells were characterized as myofibroblasts, and represent liver connective tissue cells involved in fibro-granulomatous reactions. They were able to sustain survival and proliferation of the multipotent myeloid cell lines FDC-P1 and DA-1 (dependent on interleukin-3 and/or granulocyte-macrophage colony stimulating factor, GM-CSF) without the addition of exogenous growth factors. This stimulation was dependent upon myeloid cell attachment to the GR cell layer; GR cell-conditioned medium had no activity. Primary murine skin fibroblasts could not sustain myelopoiesis. The endogenous growth-factor was identified as GM-CSF by neutralization assays with monoclonal antibodies. The stimulation of myelopoiesis occurred also when GR cells had been fixed with glutardialdehyde. The observed stimulatory activity was dependent upon heparan sulphate proteoglycans (HSPGs) associated with GR cell membranes. It could be dislodged from the cell layer with heparin or a high salt buffer. Our results indicate a molecular interaction between endogenous growth-factor and HSPGs; this interaction may be responsible for the stabilization and presentation of growth factors in myelopoietic stromas, mediating extramedullar proliferation of myeloid cells in periovular granulomas.

Potential for variability through multiple gene products of bacteriophage ΦX174

Nature ◽  
1978 ◽  
Vol 274 (5666) ◽  
pp. 34-37 ◽  
Author(s):  
Thomas J. Pollock ◽  
Irwin Tessman ◽  
Ethel S. Tessman
Keyword(s):  
Gene Products ◽  
Multiple Gene

Molecular Insights into Regulation of L-Type Ca Channel Function

Physiology ◽  
1991 ◽  
Vol 6 (6) ◽  
pp. 277-281 ◽  
Author(s):  
P Lory ◽  
G Varadi ◽  
A Schwartz
Keyword(s):  
Structure Function ◽  
Splice Variants ◽  
Ca Channel ◽  
Gene Products ◽  
Ca Channels ◽  
Channel Activity ◽  
Excitable Cells ◽  
Multiple Gene ◽  
Channel Function ◽  
Voltage Dependent

The diversity of voltage-dependent Ca channels is well documented. How excitable cells produce their specific Ca channel activity is being approached by structure-function studies. The implications of multiple gene products, splice variants, and subunit assembly in Ca channel function are updated in this review.

118. CHARACTERISATION OF HEPARAN SULPHATE PROTEOGLYCANS IN THE MATURING CUMULUS OOCYTE COMPLEX

2009 ◽  
Vol 21 (9) ◽  
pp. 37
Author(s):  
L. N. Watson ◽  
M. Sasseville ◽  
R. B. Gilchrist ◽  
D. L. Russell
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Cell Surface ◽  
Transforming Growth Factor ◽  
Heparan Sulphate ◽  
Cumulus Cells ◽  
Receptor Interaction ◽  
Heparan Sulphate Proteoglycans ◽  
Tgfβ Superfamily

Many growth factors including members of the transforming growth factor beta (TGFβ) superfamily and epidermal growth factor (Egf)-like ligands signal via interactions with heparan sulphate proteoglycans (HSPGs). Cell surface HSPGs can act by sequestering ligands at their site of action, by presenting a ligand to its signalling receptor, or by preventing ligand-receptor interaction. The oocyte secreted factors (OSF) growth differentiation factor 9 and bone morphogenetic protein 15 are members of the TGFβ superfamily that act selectively on cumulus cells. Conversely Egf-like ligands are secreted by mural granulosa cells and transmit LH-induced signals to cumulus cells. We investigated the possibility that HSPGs contribute to the spatially restricted responses these signals exert on cumulus cells. Syndecan-1 and Glypican-1 are cell surface HSPGs that are involved in numerous biological processes, including growth factor regulation, cell proliferation and differentiation. Microarray analysis showed Syndecan-1 and Glypican-1 mRNA expression induced 6-fold (P=10-9) and 3-fold (P=10-7) respectively in Egf+FSH stimulated cumulus oocyte complexes (COCs). Furthermore, Syndecan-1 and Glypican-1 mRNA were induced 27- and 16-fold respectively in COCs after hCG treatment of mice. Syndecan-1 and Glypican-1 protein was localised specifically to the COC through immunohistochemical analysis. In Vitro Maturation (IVM) of oocytes is a valuable alternative to gonadotropin mediated superovulation, but IVM COCs are less competent than those matured in vivo. Several components of the COC have been shown to be altered in IVM, including the chondroitin sulphate proteoglycan Versican. COCs from mice that underwent IVM in the presence of Egf+FSH and cilostamide for 16 hours had >16 fold reduced mRNA for Syndecan-1 when compared with In Vivo matured COCs. The lack of Syndecan-1 in IVM COCs could reduce signalling capacity of growth factors including OSFs. This may contribute to the reduced capacity of IVM oocytes to fertilise and produce a healthy embryo, and ultimately, a healthy offspring.

scholarly journals Rosetting revisited: a critical look at the evidence for host erythrocyte receptors in Plasmodium falciparum rosetting

Parasitology ◽  
2019 ◽  
Vol 147 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Fiona McQuaid ◽  
J. Alexandra Rowe
Keyword(s):  
Severe Malaria ◽  
Blood Group ◽  
Molecular Mechanisms ◽  
Heparan Sulphate ◽  
Receptor Ligand ◽  
Erythrocyte Invasion ◽  
Uninfected Erythrocyte ◽  
Ligand Interactions ◽  
Group A ◽  
Glycophorin C

AbstractMalaria remains a major cause of mortality in African children, with no adjunctive treatments currently available to ameliorate the severe clinical forms of the disease. Rosetting, the adhesion of infected erythrocytes (IEs) to uninfected erythrocytes, is a parasite phenotype strongly associated with severe malaria, and hence is a potential therapeutic target. However, the molecular mechanisms of rosetting are complex and involve multiple distinct receptor–ligand interactions, with some similarities to the diverse pathways involved in P. falciparum erythrocyte invasion. This review summarizes the current understanding of the molecular interactions that lead to rosette formation, with a particular focus on host uninfected erythrocyte receptors including the A and B blood group trisaccharides, complement receptor one, heparan sulphate, glycophorin A and glycophorin C. There is strong evidence supporting blood group A trisaccharides as rosetting receptors, but evidence for other molecules is incomplete and requires further study. It is likely that additional host erythrocyte rosetting receptors remain to be discovered. A rosette-disrupting low anti-coagulant heparin derivative is being investigated as an adjunctive therapy for severe malaria, and further research into the receptor–ligand interactions underlying rosetting may reveal additional therapeutic approaches to reduce the unacceptably high mortality rate of severe malaria.

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