Developmental Role of Zebrafish Protease-Activated Receptor 1 (PAR1) in the Cardio-Vascular System

Abstract

Thrombin receptor, F2R or PAR1 is a G-protein coupled receptor, located in the membrane of endothelial cells. It has been initially found to transduce signals in hemostasis, but recently also known to act in cancer and in vascular development. Mouse embryos lacking PAR1 function die from hemorrhages with varying frequency at midgestation. We have performed a survey of potential PAR1 homologs in the zebrafish genome and identified a teleost ortholog of mammalian PAR1. Knockdown of par1 function in zebrafish embryos demonstrates a requirement for Par1 in cardio-vascular development. Furthermore, we show that function of Par1 requires the presence of a phylogenetically conserved proteolytic cleavage site and a second intracellular domain. Altogether our results demonstrate a high degree of conservation of PAR1 proteins in the vertebrate lineage in respect to amino acid sequence as well as protein function.

Quantitative assessment of angiogenesis, perfused blood vessels and endothelial tip cells in the postnatal mouse brain

“…Furthermore, a simultaneous analysis of endothelial tip cells on the same slides was not possible owing to the different fixation protocols. Methods to analyze angiogenesis and endothelial tip cells inside and outside the CNS have been described for the embryonic mouse hindbrain 9 , the postnatal mouse retina 34,57 and the embryonic zebrafish intersegmental vessels 58,59 . Moreover, perfused vessels and tip cells have been addressed in the retina 23,43 , and a recent study investigated vessel perfusion in the postnatal mouse brain 22 but did not show a simultaneous visualization and quantification of the sprouting activity.…”

Matrix metalloproteases and PAR1 activation

“…[75][76][77][78] PAR1 (f2R) knockdown results in a weaker heartbeat and slower blood flow in zebrafish. 78 Conversely, PAR1 stimulation results in cardiomyocyte hypertrophy and increased DNA synthesis in cardiac fibroblasts. 76 Cardiacspecific overexpression of PAR1 led to heart failure in mice, whereas genetic deletion of PAR1 blunted the injury response after ischemia and reperfusion.…”

Contractile properties of slow and fast skeletal muscles from protease activated receptor‐1 null mice

“…PARs act as sensors of tissue injury and play an important role in the inflammatory response to tissue damage . They may also play an important role in skeletal muscle development . PAR‐1 and PAR‐2 have been identified in cultured myoblasts and myotubes, and PAR activation by thrombin has been shown to be mitogenic, significantly increasing myoblast proliferation in vitro …”

“…7 They may also play an important role in skeletal muscle development. [8][9][10] PAR-1 and PAR-2 have been identified in cultured myoblasts and myotubes, 11,12 and PAR activation by thrombin has been shown to be mitogenic, significantly increasing myoblast proliferation in vitro. 13,14 Considering the high levels of PAR expression found during skeletal muscle development and the significant role PARs can play in cell behavior in skeletal muscle, we hypothesized that the absence of PAR-1 mediated signaling during development would result in significant alterations in the contractile phenotype of adult skeletal muscle.…”