Role of formic receptors in soluble urokinase receptor–induced human vascular smooth muscle migration

Abstract

Background Vascular smooth muscle cell (VSMC) migration in response to urokinase is dependent on binding of the urokinase molecule to the urokinase receptor uPAR and cleavage of the receptor. The aim of this study is to examine the role of the soluble uPAR (suPAR) in vascular smooth muscle cell migration. Methods Human VSMCs were cultured in vitro. Linear wound and Boyden microchemotaxis assays of migration were performed in the presence of suPAR. Inhibitors to G-protein signaling and kinase activation were employed to study these pathways. Assays were performed for MAPK and EGFR activation. Results suPAR induced concentration-dependent migration of VSMC, which was G protein-dependent and was blocked by Gαi and Gβγ inhibitors. Removal of the full uPAR molecule by incubation of the cells with a phospholipase did not interfere with this response. suPAR induced ERK1/2, p38MAPK and JNK activation in a Gαi/Gβγ-dependent manner and interruption of these signaling pathways prevented suPAR-mediated migration. suPAR activity was independent of plasmin activity. suPAR did not activate EGFR. Interruption of the low affinity N-formyl-Met-Leu-Phe receptor (FPRL1) but not high affinity N-formyl-Met-Leu-Phe receptor (FPR) prevented cell migration and activation in response to suPAR. suPAR increased MMP-2 expression and activity, and this was dependent on the low affinity N-formyl-Met-Leu-Phe receptor (FPRL1) and ERK1/2. Conclusion suPAR induces human smooth muscle cell activation and migration independent of the full uPAR through activation of the G protein-coupled receptor FPRL1 which is not linked to the plasminogen activation cascade.

The Role of Fibrinolytic Regulators in Vascular Dysfunction of Systemic Sclerosis

“…uPAR is cleaved between the D1 and D2 domains and the GPI-anchor domain by various enzymes, including uPA, plasmin, MMP-3, MMP-12, MMP-19, MMP-25, GPI-specific phospholipase D, and cathepsin G, to form soluble uPAR (suPAR; full length D1-D3, D2D3, and D1) [66]. suPAR activates the G protein-coupled receptor N-formyl-Met-Leu-Phe (FPRL1) and regulates vascular smooth muscle cell (VSMC) migration, the recruitment of monocytes, stem cell mobilization, and leukocyte trafficking [66,67,68]. suPAR is also associated with thrombosis and the inhibition of plasmin generation [69].…”

TEX101, a glycoprotein essential for sperm fertility, is required for stable expression of Ly6k on testicular germ cells

“…Many other GPI-anchored proteins, such as uPAR 15 , CD14 16 , CD16b 17 , CD55 18 , GPI-80 19 are known to be released in soluble forms which may possess biological functions. For instance, soluble uPAR is known to induce smooth muscle cell activation and migration 20 . Although the biological functions of soluble types of both Ly6k and TEX101 remain unclear, the molecules may play a role in successful fertilization, similar to the GPI-anchoring forms.…”

Inflammation and N-formyl peptide receptors mediate the angiogenic activity of human vitreous humour in proliferative diabetic retinopathy

“…Various danger-associated molecular pattern host-derived peptides can activate FPRs [12]. Notably, the FPR ligands serum amyloid A, LL-37 and Hp (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) have been involved in the regulation of neovascularisation under inflammatory conditions [12]. High levels of serum amyloid A are detectable in the vitreous and plasma of PDR patients [43] and in eyes with macular oedema [44,45] whereas, to the best of our knowledge, no data are available about the levels of other FPR ligands in PDR vitreous.…”

“…N-formyl peptide receptors (FPRs) are involved in the recruitment and activation of immune cells in response to pathogen-associated molecular patterns. In addition, experimental evidence implicates FPRs in angiogenic responses linked to inflammation [12], and FPR interaction with the urokinase-type plasminogen activator (uPA)/uPA receptor (uPAR) system may stimulate angiogenesis in a proteaseindependent manner [13][14][15]. Accordingly, the uPARderived tetrapeptide Ac-L-Arg-Aib-L-Arg-L-Cα(Me)Phe-NH 2 (UPARANT) competes with formyl-methionyl-leucyl phenylalanine (fMLF) peptide for binding to FPRs and is endowed with a significant anti-angiogenic activity in vitro and in vivo [16,17].…”