Amino-terminal fragments of laminin γ2 chain retract vascular endothelial cells and increase vascular permeability.
Bottom Line: Such effects of γ2pf led to prominent actin stress fiber formation in HUVECs, which was blocked by a ROCK inhibitor.As possible receptors, γ2pf interacted with heparan sulfate proteoglycans on the surface of HUVECs.Moreover, we localized the active site of γ2pf to the N-terminal epidermal growth factor-like repeat.
Affiliation: Department of Genome Science, Graduate School of Integrated Science and Nanobioscience, Yokohama City University, Yokohama, Japan; Division of Cell Biology, Kihara Institute for Biological Research, Yokohama City University, Yokohama, Japan.Show MeSH
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Mentions: The Lmγ2 chain is cleaved at a specific site of domain III in the short arm (γ2SA) by some proteinases, releasing the N-terminal fragment, named γ2pf (Fig. 1a). It was previously found that γ2SA has tumor-promoting activity in vivo.(28) To examine the biological activities of the γ2 chain toward vascular endothelial cells, we prepared the full-length γ2 and its various N-terminal fragments, including γ2pf, γ2dV, and γ2SA (Fig. 1b). Among them, γ2pf and γ2dV were mainly used in this study because of their high purity and relative importance.(36) When the growth effect of γ2pf on endothelial cells (HUVECs) was examined, it showed a statistically significant but faint growth-stimulatory effect (Fig. 1c). In the two-chamber assay, γ2pf scarcely stimulated the migration of HUVECs (Fig. S1a). However, when γ2pf was added to the monolayer culture of HUVECs, these cells became markedly retracted or shrunken compared with untreated cells (Fig. 1d). Such a morphological change was not observed when the epithelial cell line MDCK was treated with γ2pf (data not shown). We also confirmed that γ2SA induced similar morphological changes in endothelial cells (Fig. S1b,c). However, γ2SA showed little growth effect on endothelial cells (data not shown).
Affiliation: Department of Genome Science, Graduate School of Integrated Science and Nanobioscience, Yokohama City University, Yokohama, Japan; Division of Cell Biology, Kihara Institute for Biological Research, Yokohama City University, Yokohama, Japan.