Secretion of Soluble Vascular Endothelial Growth Factor Receptor 1 (sVEGFR1/sFlt1) Requires Arf1, Arf6, and Rab11 GTPases

Abstract

The soluble form of vascular endothelial growth factor receptor 1 (sVEGFR-1/sFlt1) is generated by alternative splicing of the FLT1 gene. Secretion of sFlt1 from endothelial cells plays an important role in blood vessel sprouting and morphogenesis. However, excess sFlt1 secretion is associated with diseases such as preeclampsia and chronic kidney disease. To date, the secretory transport process involved in the secretion of sFlt1 is poorly understood. In the present study, we investigated the itinerary of sFlt1 trafficking along the secretory pathway. To understand the timecourse of sFlt1 secretion, endothelial cells stably expressing sFlt1 were metabolically radiolabeled with [35S]-methionine and cysteine. Our results indicate that after initial synthesis the levels of secreted [35S]-sFlt1 in the extracellular medium peaks at 8 hours. Treatment with brefeldin A (BFA), a drug which blocks trafficking between the endoplasmic reticulum (ER) and the Golgi complex, inhibited extracellular release of sFlt1 suggesting that ER to Golgi and intra-Golgi trafficking of sFlt1 are essential for its secretion. Furthermore, we show that ectopic expression of dominant-negative mutant forms of Arf1, Arf6, and Rab11 as well as siRNA-mediated knockdown of these GTPases block secretion of sFlt1 during normoxic and hypoxic conditions suggesting role for these small GTPases. This work is the first to report role of regulatory proteins involved in sFlt1 trafficking along the secretory pathway and may provide insights and new molecular targets for the modulation of sFlt-1 release during physiological and pathological conditions.

Proton Pump Inhibitors Decrease Soluble fms-Like Tyrosine Kinase-1 and Soluble Endoglin Secretion, Decrease Hypertension, and Rescue Endothelial Dysfunction

“…Given Jung et al 25 previously concluded that these proteins facilitate sFlt-1 secretion from cells, we examined whether PPIs may decrease sFlt-1 secretion by inhibiting the expression of these proteins. Treating trophoblast with esomeprazole in fact increased ARF1 expression ( Figure S4A and S4B) and did not affect RAB11 expression ( Figure S4C and S4D).…”

Advanced oxidation protein products enhances soluble Fms-like tyrosine kinase 1 expression in trophoblasts: A possible link between oxidative stress and preeclampsia

“…The drawbacks of the present study are, regarding other sources of sFlt-1, previous studies demonstrated that first trimester decidual cells and endothelial cells could also express sFlt-1 [27,28]. Moreover, mounting evidences suggested that AOPPs may exert its cytotoxic effects through the receptor of advanced glycation end products (RAGE) [18,30].…”

The myosin motor Myo1c is required for VEGFR2 delivery to the cell surface and for angiogenic signaling

“…5A) (21,27). We then assessed the intracellular distribution of VEGFR2 in the presence or absence of VEGF in cell lines stably expressing either scr-shRNA or shMyo1c by immunofluorescence imaging.…”