Nucleoside diphosphate kinase B regulates angiogenic responses in the endothelium via caveolae formation and c-Src-mediated caveolin-1 phosphorylation

Abstract

Nucleoside diphosphate kinase B (NDPK-B) is an enzyme required for nucleoside triphosphate homeostasis, which has been shown to interact with caveolin-1 (Cav-1). In endothelial cells (ECs), NDPK-B contributes to the regulation of angiogenesis and adherens junction (AJ) integrity. We therefore investigated whether an interaction of NDPK-B with Cav-1 in ECs is required for this regulation and the involvement of VEGF signaling herein. We report that simultaneous depletion of NDPK-B/Cav-1 in HUVECs synergistically impaired sprouting angiogenesis. NDPK-B depletion alone impaired caveolae formation, VEGF-induced phosphorylation of c-Src/Cav-1 but not of ERK1/2/AKT/eNOS. In vivo, Cav-1 mice showed impaired retinal vascularization at postnatal-day five, whereas NDPK-B mice did not. Primary mouse brain ECs (MBMECs) from NDPK-B mice showed no change in caveolae content and transendothelial-electrical resistance upon VEGF stimulation. Interestingly, NDPK-B MBMECs displayed an accumulation of intracellular vesicles and increased Cav-1 levels. Dextran tracer analysis showed increased vascular permeability in the brain of NDPK-B mice compared to wild type. In conclusion, our data indicate that NDPK-B is required for the correct localization of Cav-1 at the plasma membrane and the formation of caveolae. The genetic ablation of NDPK-B could partially be compensated by an increased Cav-1 content, which restored caveolae formation and some endothelial functions.

Regulation of heterotrimeric G-protein signaling by NDPK/NME proteins and caveolins: an update

“…21 Cav1-deficient mice also show impaired angiogenesis in several models. [71][72][73] These data suggest a common, very basic function of NDPK-B in caveolae formation. Indeed, in NDPK-B-deficient fibroblasts as well as in NDPK-B-depleted endothelial cells, Cav1 does not reach the plasma membrane and gets stocked in intracellular vesicular structures that likely represent, for example, lipid bodies.…”

“…Indeed, in NDPK-B-deficient fibroblasts as well as in NDPK-B-depleted endothelial cells, Cav1 does not reach the plasma membrane and gets stocked in intracellular vesicular structures that likely represent, for example, lipid bodies. 21,38,71 In accordance, the number of caveolae at the plasma membrane was drastically reduced. This phenotype could be rescued by the re-expression of NDPK-B.…”

“…29,39 Although in the knockdown fish angiogenic vessel formation was severely hampered, the physiological angiogenesis in the retina of newborn NDPK-B − / − mice was not altered, whereas retinal vessel formation in Cav1 − / − mice was delayed. 21,71 These data argue for a compensation of the lack of NDPK-B, which might rescue caveolae formation in newborn NDPK-B − / − mice. Indeed, as detected in brain endothelial cells of NDPK-B − / − mice, the amount of cellular Cav1 was increased and the number of caveolae was normalized.…”

“…Indeed, as detected in brain endothelial cells of NDPK-B − / − mice, the amount of cellular Cav1 was increased and the number of caveolae was normalized. 71 Interestingly, the amount of intracellular vesicles was also substantially increased, which indicates that the slower transport of Cavcontaining vesicles was compensated by a higher number of such vesicles. 71 This mechanism, whereas it might be able to counteract the NDPK-B deficiency and uphold the required amount of caveolae under physiological conditions, is apparently not able to cope with pathological stress conditions.…”

“…38,41 This close association has been confirmed in cardiomyocytes, endothelial cells, and embryonic fibroblasts. 21,38,41,71 In addition, the phenotypes in loss-ofexpression models of NDPK-B and Cavs are overlapping. Both Cav3-and NDPK-B-depleted zebrafish larvae show an impaired cardiac contractility.…”