Actions of the protein kinase WNK1 on endothelial cells are differentially mediated by its substrate kinases OSR1 and SPAK

Abstract

The with no lysine (K) (WNK) family of enzymes is best known for control of blood pressure through regulation of the function and membrane localization of ion cotransporters. In mice, global as well as endothelial-specific WNK1 gene disruption results in embryonic lethality due to angiogenic and cardiovascular defects. WNK1−/− embryos can be rescued by endothelial-specific expression of a constitutively active form of the WNK1 substrate protein kinase OSR1 (oxidative stress responsive 1). Using human umbilical vein endothelial cells (HUVECs), we explored mechanisms underlying the requirement of WNK1-OSR1 signaling for vascular development. WNK1 is required for cord formation in HUVECs, but the actions of the two major WNK1 effectors, OSR1 and its close relative SPAK (STE20/SPS1-related proline-, alanine-rich kinase), are distinct. SPAK is important for endothelial cell proliferation, whereas OSR1 is required for HUVEC chemotaxis and invasion. We also identified the zinc-finger transcription factor Slug in WNK1-mediated control of endothelial functions. Our study identifies a separation of functions for the WNK1-activated protein kinases OSR1 and SPAK in mediating proliferation, invasion, and gene expression in endothelial cells and an unanticipated link between WNK1 and Slug that is important for angiogenesis.endothelium | angiogenesis | migration | EMT | Slug

WNK Kinases in Development and Disease

“…Although it is not known if WNK1 acts downstream of Vegfr in mice, based on the fish and mouse data Wnk1 may have a conserved role in vascular development in humans (Lai et al, 2014; Xie et al, 2009; Xie et al, 2013). Such a function would also be consistent with recent data showing a requirement for WNK1 in human umbilical vein endothelial cell (HUVECs) and human dermal microvascular endothelial cell (HDMECs) models of in vitro angiogenesis (Dbouk et al, 2014). …”

“…The WNK mutations are transmitted in an autosomal dominant fashion and result in high blood pressure and high serum potassium concentrations in affected individuals (Wilson et al, 2001). This phenotype suggested that WNKs may play a role in renal physiology, and this has been substantiated in extensive subsequent research, as recently reviewed (Dbouk et al, 2014; Hadchouel et al, 2016). Consistent with this, mutations in the E3 ubiquitin ligase complex components, Kelch-like 3 and Cullin 3, were also found to cause PHAII/FHHt (Boyden et al, 2012; Louis-Dit-Picard et al, 2012), likely due to their role in WNK degradation (reviewed in (Ferdaus and McCormick, 2016)).…”

“…Since WNKs can positively regulate Wnt signaling in Drosophila and cultured human cells, it is conceivable that WNKs affect Wnt related cancers such as the ones of the colon that are frequently caused by increased Wnt signaling (Clevers and Nusse, 2012). To this end, it was recently shown that β-Catenin is an (indirect) transcriptional target of WNK1 and that the proliferation of certain cancer cell lines with high β-Catenin activity is dependent on WNK1 (Dbouk et al, 2014; Rosenbluh et al, 2012). Furthermore, reduction of WNK1 also lowers levels of the EMT (epithelial mesenchymal transition) transcription factor Slug, thereby possibly having the potential to favor metastasis formation (Dbouk et al, 2014).…”

Multistep regulation of autophagy by WNK1

“…Previous studies using gene disruption in mice suggested that OSR1 and WNK1 have some overlapping functions in endothelial cells during cardiovascular development (65), and further in vitro studies suggested different functions of OSR1 and SPAK (22). In examining the possibility that OSR1 or SPAK induce the effects of WNK1 on autophagy, we found that depletion of SPAK, but not OSR1, stimulated autophagy.…”

“…It is noteworthy that mutations in the regulatory components of the WNK pathway, including WNK1, WNK4, kelch-likes (KLHLs), and cullins, have been shown to cause increased expression of WNKs and ion reabsorption defects in kidney that lead to hypertension-related genetic diseases, such as Gordon's syndrome (pseudohypoaldosteronism II) (12)(13)(14)(15)(16). In addition, WNKs have been linked to the regulation of cell proliferation (17,18), cell death (19), cell migration (20)(21)(22)(23), endocytosis (24)(25)(26)(27), and angiogenesis (22,28). They also impact multiple signal transduction pathways, including the ERK1/2 and ERK5 MAP kinase pathways (17,29).…”