PubMed · 13380869
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A SANDERUD. 1956-11-15. [Aortic arch abnormalities].. https://pubmed.ncbi.nlm.nih.gov/13380869/
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OBJECTIVE: Protease-activated receptors (PARs) mediate DNA synthesis in endothelial cells when activated by serine proteases. However, despite the existence of heterogeneity among endothelial cells from each tissue, the responses to PAR-1, PAR-2, and PAR-4 activation are poorly defined and compared between endothelial cells from different sites. The aim of this study was to investigate whether PAR-mediated DNA synthesis differed in various endothelial cell types. METHODS: We examined the incorporation of BrdU by human pulmonary artery endothelial cells (HPAECs), human aortic endothelial cells (HAECs), and human umbilical vein endothelial cells (HUVECs). RESULTS: When the endothelial cells were treated with the selective PAR-1-activating peptide, SFLLRN, HAECs showed the highest BrdU incorporation rate (182 +/- 28%). In contrast, treatment with the PAR-2-activating peptide, SLIGKV, resulted in the highest BrdU incorporation rate (173 +/- 37%) in HPAECs, when pretreated with TNF-alpha. The PAR-4-activating peptide, GYPGQV, induced DNA synthesis in HPAECs and HAECs, but not in HUVECs. CONCLUSION: These findings suggest that each PAR preferentially targets an endothelial cell type, and thus plays a distinct role in diverse physiological or pathological conditions.
The elastin-derived peptide val-ala-pro-gly (VAPG) may be useful as a biospecific cell adhesion ligand for smooth muscle cells. By grafting the peptide sequence into a hydrogel material, we were able to assess its effects on smooth muscle cell adhesion and spreading. These materials are photopolymerizable hydrogels based on acrylate-terminated derivatives of polyethylene glycol (PEG). Because of their high PEG content, these materials are highly resistant to protein adsorption and cell adhesion. However, PEG diacrylate derivatives can be mixed with adhesive peptide-modified PEG monoacrylate derivatives to facilitate cell adhesion. Following photopolymerization, PEG monoacrylate derivatives are grafted into the hydrogel network formed by the PEG diacrylate. This results in covalent immobilization of adhesive peptides to the hydrogel via a flexible linker chain. The resistance of PEG to protein adsorption makes it an ideal material for this model system since cell-material interactions are limited to biomolecules that are covalently incorporated into the material. In this case we were able to demonstrate that VAPG is specific for adhesion of smooth muscle cells. It also was shown that fibroblasts, endothelial cells, and platelets cannot adhere to VAPG. In addition, not only was smooth muscle cell adhesion dependent on ligand concentration, but also cell spreading increased with increasing ligand concentration.
Diabetic vessels undergo structural changes that are linked to a high incidence of cardiovascular diseases. Reactive oxygen species (ROS) mediate cell signalling in the vasculature, where they can promote cell growth and activate redox-regulated transcription factors, like activator protein-1 (AP-1) or nuclear factor-kappaB (NF-kappaB), which are involved in remodelling and inflammation processes. Amadori adducts, formed through nonenzymatic glycosylation, can contribute to ROS formation in diabetes. In this study, we analysed whether Amadori-modified human oxyhaemoglobin, glycosylated at either normal (N-Hb) or elevated (E-Hb) levels, can induce cell growth and activate AP-1 and NF-kappaB in cultured human aortic smooth muscle cells (HASMC). E-Hb (1 nm-1 x microm), but not N-Hb, promoted a concentration-dependent increase in cell size from nanomolar concentrations, although it failed to stimulate HASMC proliferation. At 10 nm, E-Hb stimulated both AP-1 and NF-kappaB activity, as assessed by transient transfection, electromobility shift assays or immunofluorescence staining. The effects of E-Hb resembled those of the proinflammatory cytokine tumour necrosis factor-alpha (TNF-alpha). E-Hb enhanced intracellular superoxide anions content and its effects on HASMC were abolished by different ROS scavengers. In conclusion, E-Hb stimulates growth and activates AP-1 and NF-kappaB in human vascular smooth muscle by redox-sensitive pathways, thus suggesting a possible direct role for Amadori adducts in diabetic vasculopathy.