Inducible expression of the cell surface heparan sulfate proteoglycan syndecan-2 (fibroglycan) on human activated macrophages can regulate fibroblast growth factor action.

Monocyte/macrophages play important roles in regulating tissue growth and angiogenesis through the controlled release of heparin-binding growth factors such as fibroblast growth factor (FGF), vascular endothelial growth factor, and heparin binding epidermal growth factor. The action of these potent growth mediators is known to be regulated by adsorption to heparan sulfate proteoglycans (HSPGs) on the surface and within the extracellular matrix of other neighboring cells, which respectively promote or restrict interactions with their signal-transducing receptors on target cells. Here we report on the nature of HSPGs inducibly expressed on the surface of macrophages that confer these cells with the capacity to regulate endogenous growth factor activity.

Molecular polymorphism of the syndecans. Identification of a hypo-glycanated murine syndecan-1 splice variant.

We have identified a cDNA that encodes a variant form of murine syndecan-1. The variant cDNA lacks the sequence corresponding to the first 132 nucleotides of the third exon of the syndecan-1 gene. The corresponding message is rare.

Semiquantitative PCR of alpha2 and alpha4 integrin mRNA shows differential response to the transcriptional modulators TGF-beta1 and TPA.

The differential expression of VLA integrins in different cell types under different conditions has been mainly studied at the protein level. Since these cell surface proteins have a rather slow turn-over, quantitative changes in their transcription may go unnoticed. The expression of alpha2 and alpha4 mRNA was studied by relative quantitative RT-PCR on Molt-4 (human T-cell lymphoma) and A875 (human melanoma) cells.

A 68-kD antigen, which is probably an N-terminal fragment of the VLA-5 alpha 5-subunit, is specific for differentiating keratinocytes.

Background: During terminal differentiation, basal keratinocytes lose gradually contact with the basement membrane, a process accompanied by the progressive functional down-regulation and loss of integrin expression. Understanding the molecular nature of this complex mechanism will eventually lead to insight into the pathogenesis of differentiation disorders of the epidermis, e.g.

Heparan sulfate proteoglycans. Essential co-factors in receptor-mediated processes with relevance to the biology of the vascular wall.

Heparan sulfate (HS), a mixed bag of complex, heterogeneous and highly charged polysaccharides, is an essential co-factor in a large number of receptor-ligand interactions and cellular pathways. These co-factor functions depend on the binding-interactions of the HS chains with the ligand or receptor, or both. These binding interactions and the ensuing functional effects often depend on defined carbohydrate sequences within the HS chains, whereby the required sequences are not always represented within all natural forms of the polysaccharide.