Origin and diversification of the plasminogen activation system among chordates

Abstract

BackgroundThe plasminogen (PLG) activation system is composed by a series of serine proteases, inhibitors and several binding proteins, which together control the temporal and spatial generation of the active serine protease plasmin. As this proteolytic system plays a central role in human physiology and pathophysiology it has been extensively studied in mammals. The serine proteases of this system are believed to originate from an ancestral gene by gene duplications followed by domain gains and deletions. However, the identification of ancestral forms in primitive chordates supporting these theories remains elusive. In addition, evolutionary studies of the non-proteolytic members of this system are scarce.ResultsOur phylogenetic analyses place lamprey PLG at the root of the vertebrate PLG-group, while lamprey PLG-related growth factors represent the ancestral forms of the jawed-vertebrate orthologues. Furthermore, we find that the earliest putative orthologue of the PLG activator group is the hyaluronan binding protein 2 (HABP2) gene found in lampreys. The prime plasminogen activators (tissue- and urokinase-type plasminogen activator, tPA and uPA) first occur in cartilaginous fish and phylogenetic analyses confirm that all orthologues identified compose monophyletic groups to their mammalian counterparts. Cartilaginous fishes exhibit the most ancient vitronectin of all vertebrates, while plasminogen activator inhibitor 1 (PAI-1) appears for the first time in cartilaginous fishes and is conserved in the rest of jawed vertebrate clades. PAI-2 appears for the first time in the common ancestor of reptiles and mammals, and represents the latest appearing plasminogen activator inhibitor. Finally, we noted that the urokinase-type plasminogen activator receptor (uPAR)—and three-LU domain containing genes in general—occurred later in evolution and was first detectable after coelacanths.ConclusionsThis study identifies several primitive orthologues of the mammalian plasminogen activation system. These ancestral forms provide clues to the origin and diversification of this enzyme system. Further, the discovery of several members—hitherto unknown in mammals—provide new perspectives on the evolution of this important enzyme system.Electronic supplementary materialThe online version of this article (10.1186/s12862-019-1353-z) contains supplementary material, which is available to authorized users.

Profile of Matrix-Remodeling Proteinases in Osteoarthritis: Impact of Fibronectin

“…PAs are found among all vertebrates, with an origin in jawed vertebrates. Ancestral forms of PAs have also been detected in lower vertebrates without an equivalent in humans [61].…”

Did evolution create a flexible ligand-binding cavity in the urokinase receptor through deletion of a plesiotypic disulfide bond?

“…It would therefore appear that the evolutionary deletion of the plesiotypic 7-8 disulfide bond in uPAR DI was essential for creating a high-affinity binding site for uPA via a flexible assembly of all three LU domains in uPAR. This proposition is well aligned with studies on the co-evolution of uPA and uPAR (32,59). Based on crystal structures of human and murine uPAR⅐ATF complexes and extensive mutagenesis (3,31,32,60), the functional hotspot residues in the ␤-hairpin of GFD for uPAR binding is well characterized in these species.…”

“…Moreover, the majority of the important residues in the uPAR-binding motif of GFD from mammals are also conserved within the class of Reptilia (Fig. S9A) and this class is also the earliest class where a bona fide uPAR orthologue with three LU domains can be traced (59). In this phylogenetic class, uPAR DI has already lost its plesiotypic 7-8 disulfide (Fig.…”

“…5A). To probe this proposition further, we performed a continuous deuterium labeling of the different uPAR disulfide variants in the presence or absence of saturating levels of GFD and determined the deuterium uptake values by MS after pepsin digestion with special emphasis on peptide (57)(58)(59)(60)(61)(62)(63)(64)(65)(66). The deuterium uptake plots for this peptide reveals a considerable variability in the flexibility of ␤IE and ␤IF in the different disulfide variants (Fig.…”

“…Deuterium uptake plots for other regions in uPAR are shown in Fig. S5, but none of those show as prominent effects as peptide (57)(58)(59)(60)(61)(62)(63)(64)(65)(66) (reporting on ␤IE and ␤IF).…”