FBXW7 regulates endothelial barrier function by suppression of the cholesterol synthesis pathway and prenylation of RhoB

Abstract

Rho GTPases control both the actin cytoskeleton and adherens junction stability and are recognized as essential regulators of endothelial barrier function. They act as molecular switches and are primarily regulated by the exchange of GDP and GTP. However, posttranslational modifications such as phosphorylation, prenylation, and ubiquitination can additionally alter their localization, stability, and activity. F-box proteins are involved in the recognition of substrate proteins predestined for ubiquitination and subsequent degradation. Given the importance of ubiquitination, we studied the effect of the loss of 62 members of the F-box protein family on endothelial barrier function in human umbilical vein endothelial cells. Endothelial barrier function was quantified by electrical cell impedance sensing and macromolecule passage assay. Our RNA interference–based screen identified FBXW7 as a key regulator of endothelial barrier function. Mechanistically, loss of FBXW7 induced the accumulation of the RhoB GTPase in endothelial cells, resulting in their increased contractility and permeability. FBXW7 knockdown induced activation of the cholesterol biosynthesis pathway and changed the prenylation of RhoB. This effect was reversed by farnesyl transferase inhibitors and by the addition of geranylgeranyl pyrophosphate. In summary, this study identifies FBXW7 as a novel regulator of endothelial barrier function in vitro. Loss of FBXW7 indirectly modulates RhoB activity via alteration of the cholesterol biosynthesis pathway and, consequently, of the prenylation status and activity of RhoB, resulting in increased contractility and disruption of the endothelial barrier.

Geranylgeranylacetone reduces cardiomyocyte stiffness and attenuates diastolic dysfunction in a rat model of cardiometabolic syndrome

“…The GGA‐induced redistribution of HSPs is characteristic of HSP activation (Guo et al, 2012; Snoeckx et al, 2001) and can be induced by geranylgeranylation (Hála & Žárský, 2019). As GGA is a structural homologue of the geranylgeranyl donor geranylgeranyl‐pyrophosphate (GGPP) (Hashimoto et al, 2005), which influences intracellular protein trafficking (Pronk et al, 2019), it is anticipated that GGA‐induced HSP redistribution results from protein geranylgeranylation.…”

Circ_CLASP2 Regulates High Glucose-Induced Dysfunction of Human Endothelial Cells Through Targeting miR-140-5p/FBXW7 Axis

“…Shao et al highlighted that FBXW7 was implicated in the regulation of transthyretin on neovascularization in diabetic retinopathy ( Shao et al, 2019 ). Moreover, FBXW7 was reported as a crucial regulator of endothelial barrier function and endothelium vasculature ( Izumi et al, 2012 ; Pronk et al, 2019 ). We verified that miR-140-5p directly targeted FBXW7 in HUVECs, and miR-140-5p regulated HG-induced cell dysfunction by FBXW7.…”

Ubiquitin-based modifications in endothelial cell–cell contact and inflammation

“…This is mainly due to the difference in their hypervariable C-terminal regions. The hypervariable region of RhoB contains more polar amino acids than that of RhoA and RhoC, and additional isoprenylation modifications have been reported for RhoB (Allal et al, 2002;Baron et al, 2000;Pronk et al, 2019). Unlike RhoA and RhoC, RhoB does not bind the ubiquitously expressed RhoGDI1 (also known as ARHGDIA) and is therefore prone to ubiquitylation and degradation (Garcia-Mata et al, 2011).…”

“…In addition, the SCF-FBXL19 E3 ligase targets Rac1 K166 for ubiquitylation and degradation, an event which requires AKT-mediated phosphorylation of Rac1 at S71 (Zhao et al, 2013). Through this pathway, FBXL19 negatively regulates Rac1 signaling; this impairs cell migration and reduces endothelial barrier integrity (Pronk et al, 2019).…”