Pleiotrophin-induced endothelial cell migration is regulated by xanthine oxidase-mediated generation of reactive oxygen species

Abstract

Pleiotrophin (PTN) is a heparin-binding growth factor that induces cell migration through binding to its receptor protein tyrosine phosphatase beta/zeta (RPTPβ/ζ) and integrin alpha v beta 3 (ανβ3). In the present work, we studied the effect of PTN on the generation of reactive oxygen species (ROS) in human endothelial cells and the involvement of ROS in PTN-induced cell migration. Exogenous PTN significantly increased ROS levels in a concentration and time-dependent manner in both human endothelial and prostate cancer cells, while knockdown of endogenous PTN expression in prostate cancer cells significantly down-regulated ROS production. Suppression of RPTPβ/ζ through genetic and pharmacological approaches, or inhibition of c-src kinase activity abolished PTN-induced ROS generation. A synthetic peptide that blocks PTN-ανβ3 interaction abolished PTN-induced ROS generation, suggesting that ανβ3 is also involved. The latter was confirmed in CHO cells that do not express β3 or over-express wild-type β3 or mutant β3Y773F/Y785F. PTN increased ROS generation in cells expressing wild-type β3 but not in cells not expressing or expressing mutant β3. Phosphoinositide 3-kinase (PI3K) or Erk1/2 inhibition suppressed PTN-induced ROS production, suggesting that ROS production lays down-stream of PI3K or Erk1/2 activation by PTN. Finally, ROS scavenging and xanthine oxidase inhibition completely abolished both PTN-induced ROS generation and cell migration, while NADPH oxidase inhibition had no effect. Collectively, these data suggest that xanthine oxidase-mediated ROS production is required for PTN-induced cell migration through the cell membrane functional complex of ανβ3 and RPTPβ/ζ and activation of c-src, PI3K and ERK1/2 kinases.

Polarization of the epithelial layer and apical localization of integrins are required for engulfment of apoptotic cells

“…We found it striking that the same α-subunit is required for both migration and engulfment: αPS3 in Drosophila and αν in mammals ( Dinkins et al, 2008 ; Shiratsuchi et al, 2012 ; Nonaka et al, 2013 ; Law et al, 2015 ; Tsirmoula et al, 2015 ). So how are migration and engulfment tied together?…”

“…Interestingly, migration in border cells and during dorsal closure requires much of the engulfment machinery ( Dinkins et al, 2008 ; Brock et al, 2012 ; Ellis et al, 2013 ), suggesting that common molecular processes are shared between migration and engulfment. We found it striking that the same α-subunit is used for both engulfment and migration in Drosophila and in mammals ( Dinkins et al, 2008 ; Shiratsuchi et al, 2012 ; Nonaka et al, 2013 ; Law et al, 2015 ; Tsirmoula et al, 2015 ). Thus, given the link between cell polarity and integrins in migratory cells, and the fact that αPS3 is required in migratory and engulfing cells, we screened for engulfment and integrin-enrichment defects in knockdowns of several genes that are associated with migration and/or integrin signaling.…”

The p38 pathway, a major pleiotropic cascade that transduces stress and metastatic signals in endothelial cells

“…On the other hand, the p38/MK2/HSP27 axis-mediated actin remodeling might play a role in the regulation of endothelial barrier, as it will be discussed below. p38-mediated actin remodeling is also compatible with the role of ROS in promoting migration of endothelial cell [ 99 , 124 ].…”

Cyclin-dependent kinase 5 mediates pleiotrophin-induced endothelial cell migration

“…RPTPβ/ζ initiates PTN signalling through cellular Src kinase (c-Src) dephosphorylation and activation that consequently leads to β 3 Tyr773 phosphorylation and activation of phosphatidylinositol 3-kinase (PI3K) 2 , 4 . Moreover, other signalling molecules, such as focal adhesion and ERK1/2 kinases 1 , nitric oxide 5 and xanthine oxidase 6 , have been shown to be activated down-stream of RPTPβ/ζ and required for PTN-induced endothelial cell migration. However, the cross-talk among all the identified signalling molecules involved, as well as novel unknown molecules that may mediate the RPTPβ/ζ migratory signalling pathways, are still to be investigated.…”