Prox1 Promotes Lineage-specific Expression of Fibroblast Growth Factor (FGF) Receptor3 in Lymphatic Endothelium: A Role for FGF Signaling in Lymphangiogenesis (original) (raw)
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Fibroblast growth factors play important roles in angiogenesis but their functions in lymphangiogenesis remain poorly understood. The homeodomain transcription factor Prox1 is essential for development of the lymphatic system by specifying lymphatic endothelial cell (LEC) fate. Here, we identify FGF receptor (FGFR) -3 as a novel Prox1 target gene. Ectopic overexpression of Prox1 in blood vascular endothelial cells upregulates FGFR-3. Prox1 induces the expression of the IIIc isoform which we also found to be the major isoform of FGFR-3 expressed in LECs. This transcriptional activation is mediated by a direct binding of Prox1 to newly identified Prox1-response elements in the FGFR-3 promoter. Consistently, FGFR-3 is upregulated in Prox1-positive newly formed lymphatic vessels during embryogenesis and its lymphatic-specific expression is maintained throughout development. We also found that FGF-1 and FGF-2 promote proliferation, migration and survival of cultured LECs without involvement of VEGFR-3. We show that FGF-2 binds to low and high-affinity receptors on LECs and is efficiently internalized and processed. Moreover, functional inhibition of FGFR-3 using siRNA represses LEC proliferation. Together, these results indicate that FGFR-3 is an initial target of Prox1 during the lymphatic cell fate specification and that FGF signaling may play an important role in lymphatic vessel development.
Genes & Development, 2014
The mammalian lymphatic vasculature is important for returning fluids from the extracellular tissue milieu back to the blood circulation. We showed previously that Prox1 dosage is important for the development of the mammalian lymphatic vasculature. The lack of Prox1 activity results in the complete absence of lymphatic endothelial cells (LECs). In Prox1 heterozygous embryos, the number of LECs is reduced because of a decrease in the progenitor pool in the cardinal vein. This reduction is caused by some progenitor cells being unable to maintain Prox1 expression. In this study, we identified Vegfr3, the cognate receptor of the lymphangiogenic growth factor Vegfc, as a dosage-dependent, direct in vivo target of Prox1. Using various mouse models, we also determined that Vegfr3 regulates Prox1 by establishing a feedback loop necessary to maintain the identity of LEC progenitors and that Vegfc-mediated activation of Vegfr3 signaling is necessary to maintain Prox1 expression in LEC progen...
An essential role for Prox1 in the induction of the lymphatic endothelial cell phenotype
The EMBO journal, 2002
The process of angiogenesis has been well documented, but little is known about the biology of lymphatic endothelial cells and the molecular mechanisms controlling lymphangiogenesis. The homeobox gene Prox1 is expressed in a subpopulation of endothelial cells that, after budding from veins, gives rise to the mammalian lymphatic system. In Prox1(-)(/-) embryos, this budding becomes arrested at around embryonic day (E)11.5, resulting in embryos without lymphatic vasculature. Unlike the endothelial cells that bud off in E11.5 wild-type embryos, those of Prox1-null embryos did not co-express any lymphatic markers such as VEGFR-3, LYVE-1 or SLC. Instead, the mutant cells appeared to have a blood vascular phenotype, as determined by their expression of laminin and CD34. These results suggest that Prox1 activity is required for both maintenance of the budding of the venous endothelial cells and differentiation toward the lymphatic phenotype. On the basis of our findings, we propose that a ...
Prox1 is a master control gene in the program specifying lymphatic endothelial cell fate
Developmental Dynamics, 2002
Early during development, one of the first indications that lymphangiogenesis has begun is the polarized expression of the homeobox gene Prox1 in a subpopulation of venous endothelial cells. It has been shown previously that Prox1 expression in the cardinal vein promotes and maintains the budding of endothelial cells that will form the lymphatic vascular system. Prox1-deficient mice are devoid of lymphatic vasculature, and in these animals endothelial cells fail to acquire the lymphatic phenotype; instead, they remain as blood vascular endothelium. To investigate whether Prox1 is sufficient to induce a lymphatic fate in blood vascular endothelium, Prox1 cDNA was ectopically expressed by adenoviral gene transfer in primary human blood vascular endothelial cells and by transient plasmid cDNA transfection in immortalized microvascular endothelial cells. Transcriptional profiling combined with quantitative real-time reverse transcriptionpolymerase chain reaction and Western blotting analyses revealed that Prox1 expression up-regulated the lymphatic endothelial cell markers podoplanin and vascular endothelial growth factor receptor-3. Conversely, genes such as laminin, vascular endothelial growth factor-C, neuropilin-1, and intercellular adhesion molecule-1, whose expression has been associated with the blood vascular endothelial cell phenotype, were down-regulated. These results were confirmed by the use of specific antibodies against some of these markers in sections of embryonic and adult tissues. These findings validate our previous proposal that Prox1 is a key player in the molecular pathway leading to the formation of lymphatic vasculature and identify Prox1 as a master switch in the program specifying lymphatic endothelial cell fate. That a single gene product was sufficient to re-program the blood vascular endothelium toward a lymphatic phenotype corroborates the close relationship between these two vascular systems and also suggests that during evolution, the lymphatic vascula-ture originated from the blood vasculature by the additional expression of only a few gene products such as Prox1.
Blood, 2008
Specification of endothelial cell (EC) fate during vascular development is controlled by distinct key regulators. While Notch plays an essential role in induction of arterial phenotypes, COUP-TFII is required to maintain the venous EC identity. Homeodomain transcription factor Prox1 functions to reprogram venous ECs to lymphatic endothelial cells (LECs). Here, we report that the venous EC fate regulator COUP-TFII is expressed in LECs throughout development and physically interacts with Prox1 to form a stable complex in various cell types including LECs. We found that COUP-TFII functions as a coregulator of Prox1 to control several lineage-specific genes including VEGFR-3, FGFR-3, and neuropilin-1 and is required along with Prox1 to maintain LEC phenotype. Together, we propose that the physical and functional interactions of the 2 proteins constitute an essential part in the program specifying LEC fate and may provide the molecular basis for the hypothesis of venous EC identity being...
The FASEB Journal, 2002
Detection of lymphatic endothelal cells (LECs) has been problematic because of the lack of specific markers. The homeobox transcription factor Prox1 is expressed in LECs of murine and avian embryos. We have studied expression of Prox1 in human tissues with immunofluorescence. In 19-wk-old human fetuses, Prox1 and vascular endothelial growth factor receptor-3 (VEGFR-3) are coexpressed in LECs of lymphatic trunks and lymphatic capillaries. Prox1 is located in the nucleus, and its expression is mutually exclusive with that of the blood vascular marker PALE. Prox1 is a constitutive marker of LECs and is found in tissues of healthy adults and lymphedema patients. Blood vascular endothelial cells (BECs) of hemangiomas express CD31 and CD34, but not Prox1. A subset of these cells is positive for VEGFR-3. Lymphatics in the periphery of hemangiomas express Prox1 and CD31, but not CD34. In lymphangiomas, LECs express Prox1, CD31, and VEGFR-3, but rarely CD34. In the stroma, spindle-shaped CD34-positive cells are present. We show that Prox1 is a reliable marker for LECs in normal and pathologic human tissues, coexpressed with VEGFR-3 and CD31. VEGFR-3 and CD34 are less reliable markers for LECs and BECs, respectively, because exceptions from their normal expression patterns are found in pathologic tissues.
BMC Developmental Biology, 2010
Background In vivo studies demonstrate that the Prox1 transcription factor plays a critical role in the development of the early lymphatic system. Upon Prox1 expression, early lymphatic endothelial cells differentiate from the cardinal vein and begin to express lymphatic markers such as VEGFR-3, LYVE-1 and Podoplanin. Subsequent in vitro studies have found that differentiated vascular endothelial cells can be reprogrammed by Prox1 to express a lymphatic gene profile, suggesting that Prox1 can initiate the expression of a unique gene signature during lymphangiogenesis. While the in vitro data suggest that gene reprogramming occurs upon Prox1 expression, it is not clear if this is a direct result of Prox1 in vascular endothelial cells in vivo. Results Overexpression of Prox1 in vascular endothelial cells during embryonic development results in the reprogramming of genes to that of a more lymphatic signature. Consequent to this overexpression, embryos suffer from gross edema that resul...
Prox1 Function Is Required for the Development of the Murine Lymphatic System
Cell, 1999
The lack of specific markers has raised problems in documenting the precise manner by which the lymphatic system develops. Here we report that the homeobox gene Prox1 is expressed in a subpopulation of endothelial cells that by budding and sprouting give rise to the lymphatic system. The initial localization of these cells in the veins and their subsequent budding are both polarized, suggesting that unidentified guidance signals regulate this process. In Prox1 null mice, budding and sprouting is arrested, although vasculogenesis and angiogenesis of the vascular system is unaffected. These findings suggest that Prox1 is a specific and required regulator of the development of the lymphatic system and that the vascular and lymphatic systems develop independently.
Inflammation induces lymphangiogenesis through up-regulation of VEGFR-3 mediated by NF- B and Prox1
Blood, 2010
B and Prox1 κ VEGFR-3 mediated by NF-Inflammation induces lymphangiogenesis through up-regulation of http://bloodjournal.hematologylibrary.org/content/115/2/418.full.html Updated information and services can be found at: (380 articles) Vascular Biology Articles on similar topics can be found in the following Blood collections http://bloodjournal.hematologylibrary.org/site/misc/rights.xhtml#repub\_requests
Development, 2020
Lymphatic vasculature is an integral part of digestive, immune and circulatory systems. The homeobox transcription factor PROX1 is necessary for the development of lymphatic vessels, lymphatic valves (LVs) and lymphovenous valves (LVVs). We and others previously reported a feedback loop between PROX1 and Vascular Endothelial Growth Factor-C (VEGF-C) signaling. PROX1 promotes the expression of the VEGF-C receptor VEGFR3 in lymphatic endothelial cells (LECs). In turn, VEGF-C signaling maintains PROX1 expression in LECs. However, the mechanisms of PROX1/VEGF-C feedback loop remain poorly understood. Whether VEGF-C signaling is necessary for LV and LVV development is also unknown. Here, we report for the first time that VEGF-C signaling is necessary for valve morphogenesis. We have also discovered that the transcriptional co-activators YAP and TAZ are required to maintain PROX1 expression in LVs and LVVs in response to VEGF-C signaling. Deletion of Yap and Taz in the lymphatic vasculatu...