Urokinase-derived peptides regulate vascular smooth muscle contraction in vitro and in vivo

Abstract

We examined the effect of urokinase (uPA) and its fragments on vascular smooth muscle cell contraction. Single-chain uPA inhibits phenylepherine (PE) -induced contraction of rat aortic rings, whereas two-chain uPA exerts the opposite effect. Two independent epitopes mediating these opposing activities were identified. A6, a capped peptide corresponding to amino acids 136-143 (KPSSPPEE) of uPA, increased the EC(50) of PE-induced vascular contraction sevenfold by inhibiting the release of calcium from intracellular stores. A6 activity was abolished by deleting the carboxyl-terminal Glu or by mutating the Ser corresponding to position 138 in uPA to Glu. A single-chain uPA variant lacking amino acids 136-143 did not induce vasorelaxation. A second epitope within the kringle of uPA potentiated PE-induced vasoconstriction. This epitope was exposed when single-chain uPA was converted to a two-chain molecule by plasmin. The isolated uPA kringle augmented vasoconstriction, whereas uPA variant lacking the kringle had no procontractile activity. These studies reveal previously undescribed vasoactive domains within urokinase and its naturally derived fragments.

A peptide derived from the nonreceptor binding region of urokinase plasminogen activator (uPA) inhibits tumor progression and angiogenesis and induces tumor cell deathin vivo

“…Our data also demonstrate that Å6 also has antiangiogenic activity resulting in substantially less factor VIII-positive hot spots in sections obtained from Å6-treated animals. The effects of Å6 on vascular contractility and signaling have also recently been demonstrated by Haj-Yehia et al (31), suggesting another possible hypothesis to explain the activity of Å6. The inhibitory effects of Å6 on vascular contractility may impede blood flow to the tumor in addition to its effects on angiogenesis.…”

“…The fact that Å6 antagonizes the activity of vasoconstricting agents such as phenylephrine and endothelin-1 suggests that part of its antitumor effects may result from a suppression of hypoxia-dependent pathways of angiogenesis in addition to the inhibition of vessel formation. Further, Å6 does not seem to affect nonstimulated vessels as no effects on vasoconstriction were observed by Haj-Yehia et al (31) in the absence of vasoconstricting stimuli. Experiments are currently under way to examine the effects of Å6 on the expression of hypoxia-related genes and the initiation of angiogenesis in tumors (angiogenic switch).…”

Oligonucleotide Microarrays Reveal Regulated Genes Related to Inward Arterial Remodeling Induced by Urokinase Plasminogen Activator

“…Third, changes in oxidation-related gene expression suggest that uPA promotes oxidative stress, which is consistent with our previous study showing increased Nox1 and Nox4 expression in response to uPA [20]. Taking into account that oxidative stress may regulate vascular tone and induce vasoconstriction (uPA itself possesses vasoactive properties [23]), we may hypothesize that the day 1 decrease in lumen and EEL areas after uPA could reflect changes in vascular tone. Fourth, the changes in gene expression were much greater at day 1 than day 4, possibly reflecting the disappearance or inactivation of uPA [11].…”

The kringle domain of urokinase-type plasminogen activator potentiates LPS-induced neutrophil activation through interaction with αVβ3 integrins

“…These effects of uPA on smooth muscle migration were dependent on the KD. Similarly, the KD is also involved in uPA-mediated contraction of vascular smooth muscle [18,24,[43][44][45]. UPA-dependent proliferation of smooth muscle and melanoma cells is similarly independent of uPAR as well as the proteolytic activity of uPA [20,45,46].…”

“…Antibodies to ␣ V and ␤ 3 integrins, as well as isotype-specific controls were purchased from Chemicon (Temecula, CA) for human integrins and PharMingen (San Diego, CA) for murine integrins. Arginine-glycine-aspartic (RGD) and arginine-glycine-glutamic (RGE) peptides were purchased from Sigma Chemical Co. Recombinant human scuPA was prepared as described previously, as were the isolated uPA domains and uPA mutants lacking specific domains [18,22,24]. The LPS concentration of the stock scuPA as well as all other solutions measured by enzyme-linked immunosorbent assay (ELISA; BioWhittaker, Rockland, ME) was Ͻ1 pg/ml.…”