Abstract-Bone morphogenetic proteins (BMPs) are involved in embryonic and adult blood vessel formation in health and disease. BMPER (BMP endothelial cell precursor-derived regulator) is a differentially expressed protein in embryonic endothelial precursor cells. In earlier work, we found that BMPER interacts with BMPs and when overexpressed antagonizes their function in embryonic axis formation. In contrast, in a BMPER-deficient zebrafish model, BMPER behaves as a BMP agonist. Furthermore, lack of BMPER induces a vascular phenotype in zebrafish that is driven by disarray of the intersomitic vasculature. Here, we investigate the impact of BMPER on endothelial cell function and signaling and elucidate its role in BMP-4 function in gain-and loss-of-function models. As shown by Western blotting and immunocytochemistry, BMPER is an extracellular matrix protein expressed by endothelial cells in skin, heart, and lung. We show that BMPER is a downstream target of FoxO3a and consistently exerts activating effects on endothelial cell sprouting and migration in vitro and in vivo. Accordingly, when BMPER is depleted from endothelial cells, sprouting is impaired. In terms of BMPER related intracellular signaling, we show that BMPER is permissive and necessary for Smad 1/5 phosphorylation and induces Erk1/2 activation. Most interestingly, BMPER is necessary for BMP-4 to exert its activating role in endothelial function and to induce Smad 1/5 activation. Vice versa, BMP-4 is necessary for BMPER activity. Taken together, BMPER is a dose-dependent endothelial cell activator that plays a unique and pivotal role in fine-tuning BMP activity in angiogenesis. Key Words: BMPER Ⅲ bone morphogenetic proteins Ⅲ vascular biology Ⅲ endothelial cell function Ⅲ signaling A ngiogenesis is a basic biological event that is involved in embryonic development but also in adult physiological and pathological conditions, such as inflammation, tumor growth, atherosclerosis, or response to ischemia. This process depends on the orchestrated function of intra-and extracellular proteins, many of which are conserved from embryonic development through adulthood. 1 Bone morphogenetic proteins (BMPs) are members of the transforming growth factor (TGF)- superfamily. Originally, they have been identified by their ability to induce ectopic bone formation and have been extensively studied during embryonic development, in which they control axis formation and organogenesis. Today, more than 20 BMP-related proteins and a number of BMP modulating proteins have been identified. 2 A growing body of evidence suggests that they serve as important regulators in vascular development and disease. 3 BMPs are extracellular proteins that signal through cell surface complexes of type I and type II serine/threonine kinase receptors. On activation, the receptors mediate intracellular signaling mainly through the Smad 1/5 transcription factors. BMP signaling is regulated at several levels: activity of R-Smads (1/5) is modulated by facilitating (eg, Smad 4) or inhibitory (eg,...
Background— The adaptive growth of blood vessels is an important protective mechanism in cardiovascular disease. However, the underlying regulatory mechanisms of this process are only partly understood. Recently, small endogenous RNAs (microRNAs [miRNAs]) were found to play an important role in embryonic and postnatal vascular development. Here, we used miRNA transcriptome analysis after induction of hind-limb ischemia in mice to screen for miRNAs involved in adaptive blood vessel growth following arterial occlusion. Methods and Results— Using miRNA arrays, we explored the miRNA expression profile during adaptive neovascularization. We describe specific changes in miRNA expression patterns and show that miRNA-100 is significantly downregulated after induction of hind-limb ischemia in mice. Our data demonstrate that miR-100 modulates proliferation, tube formation, and sprouting activity of endothelial cells and migration of vascular smooth muscle cells and functions as an endogenous repressor of the serine/threonine protein kinase mammalian target of rapamycin (mTOR). Whereas miR-100 inhibition increased mTOR levels in endothelial cells, overexpression of miR-100 reduced mTOR expression and consequently attenuated cellular proliferation. Supporting this notion, overexpression of an mTOR construct lacking the miRNA binding site rescued the inhibitory effect of miR-100 on cell proliferation. Accordingly, miR-100 inhibition by specific antagomirs in vivo stimulated angiogenesis and resulted in functional improvement of perfusion after femoral artery occlusion in mice. In contrast, treatment with the mTOR inhibitor rapamycin had the opposite effect. Conclusions— Our data demonstrate that miR-100 has an antiangiogenic function and represses mTOR signaling in endothelial and vascular smooth muscle cells. Inhibition of miR-100 could be a novel approach for the modulation of blood vessel growth and other mTOR-dependent processes.
We demonstrate that ERK1/2 functions as an alternative pathway in BMP-4 signaling in HUVECs. Capillary sprouting induced by BMP-4 is dependent on ERK phosphorylation. ERK is essential for efficient transduction of BMP signals and serves as a positive feedback mechanism. On the other hand, stimulation of Smad 6 inhibits ERK activation and thus results in a negative feedback loop to fine-tune BMP signaling in HUVECs.
The endothelium plays a pivotal role in vascular inflammation. Here we study bone morphogenetic protein (BMP) signaling in endothelial inflammation and in particular the role of BMPER, an extracellular BMP modulator that is important in vascular development and angiogenesis. Using the BMP antagonist dorsomorphin or BMP2 as an agonist we show that BMP signaling is essential for the inflammatory response of vascular endothelial cells as demonstrated by intravital microscopy. We found that BMPER is decreased in inflammation similar to vascular protective genes like KLF2 and eNOS. Using in vitro and in vivo models we show that BMPER is down-regulated through the TNF␣-NFB-KLF2 signaling pathway. Functionally, lack of BMPER induced by siRNA or in BMPER ؉/؊ mice confers a proinflammatory endothelial phenotype with reduced eNOS levels and enhanced expression of adhesion molecules leading to increased leukocyte adhesion and extravasation in ex vivo and in vivo experiments. Vice versa, addition of BMPER exerts endothelium protective functions and antagonizes TNF␣ induced inflammation. Mechanistically, we demonstrate that these effects of BMPER are dependent on BMP signaling because of enhanced NFB activity. In conclusion, the BMP modulator BMPER is a new protective regulator of vascular inflammation that modulates leukocyte adhesion and migration in vitro and in vivo. (Blood. 2011;118(18):5040-5049) IntroductionThe endothelium plays a pivotal role in the response to vascular inflammation. Inflammatory stimuli such as TNF␣ induce endothelial dysfunction and confer a proadhesive endothelial phenotype. 1 These events are important under physiologic conditions in wound healing as well as in inflammatory diseases like sepsis or atherosclerosis. Endothelial dysfunction initiates a cascade of events with leukocyte adhesion in a central position. It is of outstanding importance to understand the underlying molecular mechanisms of this process and to identify new mediators of a proadhesive endothelial phenotype.In endothelial dysfunction hundreds of genes are induced but inhibition of genes is a relatively rare event. 1 Among these few genes Kruepple like factor 2 (KLF2) and endothelial NO synthase (eNOS) are well characterized examples. 2 Consistent with downregulation in endothelial dysfunction KLF2 is up-regulated by laminar (physiologic) flow conditions or statin therapy. 3,4 KLF2 then up-regulates the expression of protective endothelial factors, such as eNOS. 5 ENOS and NO attenuated inflammatory response via inhibition of endothelial adhesion molecules VCAM-1 and ICAM-1 in vitro and in vivo. 6,7 Vice versa reduction of eNOS and endothelial NO caused endothelial dysfunction at the vascular wall reflected by proinflammatory endothelial phenotype with increasing leukocyte endothelial interaction. [7][8][9] Bone morphogenetic proteins (BMPs) are important regulators in blood vessel formation and vascular disease. 10 BMPs are expressed in atheroprone regions of blood vessels and are down-regulated in the endothelium under protec...
SummaryGrowth and regeneration of blood vessels are crucial processes during embryonic development and in adult disease. Members of the bone morphogenetic protein (BMP) family are growth factors known to play a key role in vascular development. The BMP pathway is controlled by extracellular BMP modulators such as BMP endothelial cell precursor derived regulator (BMPER), which we reported previously acts proangiogenically on endothelial cells in a concentration-dependent manner. Here, we explore the function of other BMP modulators, especially Tsg, on endothelial cell behaviour and compare them to BMPER. In Matrigel assays, BMP modulators chordin and noggin had no stimulatory effect; however, gremlin and Tsg enhanced human umbilical vein endothelial cell (HUVEC) sprouting. As the activation dynamics of Tsg were similar to those of BMPER, we further investigated the proangiogenic effect of Tsg on endothelial cells. Tsg enhanced endothelial cell ingrowth in the mouse Matrigel plug assay as well as HUVEC sprouting, migration and proliferation in vitro, dependent on Akt, Erk and Smad signalling pathway activation in a concentration-dependent manner. Surprisingly, silencing of Tsg also increased HUVEC sprouting, migration and proliferation, which is again associated with Akt, Erk and Smad signalling pathway activation. Furthermore, we reveal that Tsg and BMPER interfere with each other to enhance proangiogenic events. However, in vivo the presence of Tsg as well as of BMPER is mandatory for regular development of the zebrafish vasculature. Taken together, our results suggest that BMPER and Tsg maintain a fine-tuned equilibrium that controls BMP pathway activity and is necessary for vascular cell homeostasis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.