The endothelial tyrosine kinase receptor Tie1 remains poorly characterized, largely owing to its orphan receptor status. Global Tie1 inactivation causes late embryonic lethality, thereby reflecting its importance during development. Tie1 also plays pivotal roles during pathologies such as atherosclerosis and tumorigenesis. In order to study the contribution of Tie1 to tumor progression and metastasis, we conditionally deleted Tie1 in endothelial cells at different stages of tumor growth and metastatic dissemination. Tie1 deletion during primary tumor growth in mice led to a decrease in microvessel density and an increase in mural cell coverage with improved vessel perfusion. Reduced angiogenesis and enhanced vascular normalization resulted in a progressive increase of intratumoral necrosis that caused a growth delay only at later stages of tumor progression. Concomitantly, surgical removal of the primary tumor decreased the number of circulating tumor cells, reduced metastasis, and prolonged overall survival. Additionally, Tie1 deletion in experimental murine metastasis models prevented extravasation of tumor cells into the lungs and reduced metastatic foci. Taken together, the data support Tie1 as a therapeutic target by defining its regulatory functions during angiogenesis and vascular abnormalization and identifying its role during metastasis.
Silvia La Porta, Lise Roth, Mahak Singhal, Carolin Mogler, Carleen Spegg, Benjamin Schieb, Xianghu Qu, Ralf H. Adams, H. Scott Baldwin, Soniya Savant, Hellmut G. Augustin
Adaptation to respiration at birth depends upon the synthesis of pulmonary surfactant, a lipid-protein complex that reduces surface tension at the air-liquid interface in the alveoli and prevents lung collapse during the ventilatory cycle. Herein, we demonstrated that the gene encoding a subunit of the endoplasmic reticulum membrane complex, EMC3, also known as TMEM111 (Emc3/Tmem111), was required for murine pulmonary surfactant synthesis and lung function at birth. Conditional deletion of Emc3 in murine embryonic lung epithelial cells disrupted the synthesis and packaging of surfactant lipids and proteins, impaired the formation of lamellar bodies, and induced the unfolded protein response in alveolar type 2 (AT2) cells. EMC3 was essential for the processing and routing of surfactant proteins, SP-B and SP-C, and the biogenesis of the phospholipid transport protein ABCA3. Transcriptomic, lipidomic, and proteomic analyses demonstrated that EMC3 coordinates the assembly of lipids and proteins in AT2 cells that is necessary for surfactant synthesis and function at birth.
Xiaofang Tang, John M. Snowball, Yan Xu, Cheng-Lun Na, Timothy E. Weaver, Geremy Clair, Jennifer E. Kyle, Erika M. Zink, Charles Ansong, Wei Wei, Meina Huang, Xinhua Lin, Jeffrey A. Whitsett
Mast cells are classically thought to play an important role in protection against helminth infections and in the induction of allergic diseases; however, recent studies indicate that these cells also contribute to neovascularization, which is critical for tissue remodeling, chronic inflammation, and carcinogenesis. Here, we demonstrate that mast cells are essential for sprouting angiogenesis in a murine model of oxygen-induced retinopathy (OIR). Although mouse strains lacking mast cells did not exhibit retinal neovascularization following hypoxia, these mice developed OIR following infusion of mast cells or after injection of mast cell tryptase (MCT). Relative hypoxia stimulated mast cell degranulation via transient receptor potential ankyrin 1. Subsequent surges in MCT stimulated retinal endothelial cells to produce monocyte chemotactic protein-1 (MCP1) and angiogenic factors, leading to sprouting angiogenesis. Mast cell stabilizers as well as specific tryptase and MCP1 inhibitors prevented the development of OIR in WT mice. Preterm infants with early retinopathy of prematurity had markedly higher plasma MCT levels than age-matched infants without disease, suggesting mast cells contribute to human disease. Together, these results suggest therapies that suppress mast cell activity should be further explored as a potential option for preventing eye diseases and subsequent blindness induced by neovascularization.
Kenshiro Matsuda, Noriko Okamoto, Masatoshi Kondo, Peter D. Arkwright, Kaoru Karasawa, Saori Ishizaka, Shinichi Yokota, Akira Matsuda, Kyungsook Jung, Kumiko Oida, Yosuke Amagai, Hyosun Jang, Eiichiro Noda, Ryota Kakinuma, Koujirou Yasui, Uiko Kaku, Yasuo Mori, Nobuyuki Onai, Toshiaki Ohteki, Akane Tanaka, Hiroshi Matsuda
Demyelination in the central nervous system (CNS) leads to severe neurological deficits that can be partially reversed by spontaneous remyelination. Because the CNS is isolated from the peripheral milieu by the blood-brain barrier, remyelination is thought to be controlled by the CNS microenvironment. However, in this work we found that factors derived from peripheral tissue leak into the CNS after injury and promote remyelination in a murine model of toxin-induced demyelination. Mechanistically, leakage of circulating fibroblast growth factor 21 (FGF21), which is predominantly expressed by the pancreas, drives proliferation of oligodendrocyte precursor cells (OPCs) through interactions with β-klotho, an essential coreceptor of FGF21. We further confirmed that human OPCs expressed β-klotho and proliferated in response to FGF21 in vitro. Vascular barrier disruption is a common feature of many CNS disorders; thus, our findings reveal a potentially important role for the peripheral milieu in promoting CNS regeneration.
Mariko Kuroda, Rieko Muramatsu, Noriko Maedera, Yoshihisa Koyama, Machika Hamaguchi, Harutoshi Fujimura, Mari Yoshida, Morichika Konishi, Nobuyuki Itoh, Hideki Mochizuki, Toshihide Yamashita
Angiogenesis is a multistep process that requires coordinated migration, proliferation, and junction formation of vascular endothelial cells (ECs) to form new vessel branches in response to growth stimuli. Major intracellular signaling pathways that regulate angiogenesis have been well elucidated, but key transcriptional regulators that mediate these signaling pathways and control EC behaviors are only beginning to be understood. Here, we show that YAP/TAZ, a transcriptional coactivator that acts as an end effector of Hippo signaling, is critical for sprouting angiogenesis and vascular barrier formation and maturation. In mice, endothelial-specific deletion of Yap/Taz led to blunted-end, aneurysm-like tip ECs with fewer and dysmorphic filopodia at the vascular front, a hyper-pruned vascular network, reduced and disarranged distributions of tight and adherens junction proteins, disrupted barrier integrity, subsequent hemorrhage in growing retina and brain vessels, and reduced pathological choroidal neovascularization. Mechanistically, YAP/TAZ activates actin cytoskeleton remodeling, an important component of filopodia formation and junction assembly. Moreover, YAP/TAZ coordinates EC proliferation and metabolic activity by upregulating MYC signaling. Overall, these results show that YAP/TAZ plays multifaceted roles for EC behaviors, proliferation, junction assembly, and metabolism in sprouting angiogenesis and barrier formation and maturation and could be a potential therapeutic target for treating neovascular diseases.
Jongshin Kim, Yoo Hyung Kim, Jaeryung Kim, Do Young Park, Hosung Bae, Da-Hye Lee, Kyun Hoo Kim, Seon Pyo Hong, Seung Pil Jang, Yoshiaki Kubota, Young-Guen Kwon, Dae-Sik Lim, Gou Young Koh
The mechanisms that promote the generation of new coronary vasculature during cardiac homeostasis and after injury remain a fundamental and clinically important area of study in the cardiovascular field. Recently, it was reported that mesenchymal-to-endothelial transition (MEndoT) contributes to substantial numbers of coronary endothelial cells after myocardial infarction. Therefore, the MEndoT has been proposed as a paradigm mediating neovascularization and is considered a promising therapeutic target in cardiac regeneration. Here, we show that preexisting endothelial cells mainly beget new coronary vessels in the adult mouse heart, with essentially no contribution from other cell sources through cell-lineage transdifferentiation. Genetic-lineage tracing revealed that cardiac fibroblasts expand substantially after injury, but do not contribute to the formation of new coronary blood vessels, indicating no contribution of MEndoT to neovascularization. Moreover, genetic-lineage tracing with a pulse-chase labeling strategy also showed that essentially all new coronary vessels in the injured heart are derived from preexisting endothelial cells, but not from other cell lineages. These data indicate that therapeutic strategies for inducing neovascularization should not be based on targeting presumptive lineage transdifferentiation such as MEndoT. Instead, preexisting endothelial cells appear more likely to be the therapeutic target for promoting neovascularization and driving heart regeneration after injury.
Lingjuan He, Xiuzhen Huang, Onur Kanisicak, Yi Li, Yue Wang, Yan Li, Wenjuan Pu, Qiaozhen Liu, Hui Zhang, Xueying Tian, Huan Zhao, Xiuxiu Liu, Shaohua Zhang, Yu Nie, Shengshou Hu, Xiang Miao, Qing-Dong Wang, Fengchao Wang, Ting Chen, Qingbo Xu, Kathy O. Lui, Jeffery D. Molkentin, Bin Zhou
Tumors are capable of coopting hematopoietic cells to create a suitable microenvironment to support malignant growth. Here, we have demonstrated that upregulation of kinase insert domain receptor (KDR), also known as VEGFR2, in a myeloid cell sublineage is necessary for malignant progression of gliomas in transgenic murine models and is associated with high-grade tumors in patients. KDR expression increased in myeloid cells as myeloid-derived suppressor cells (MDSCs) accumulated, which was associated with the transformation and progression of low-grade fibrillary astrocytoma to high-grade anaplastic gliomas. KDR deficiency in murine BM-derived cells (BMDCs) suppressed the differentiation of myeloid lineages and reduced granulocytic/monocytic populations. The depletion of myeloid-derived KDR compromised its proangiogenic function, which inhibited the angiogenic switch necessary for malignant progression of low-grade to high-grade tumors. We also identified inhibitor of DNA binding protein 2 (ID2) as a key upstream regulator of KDR activation during myeloid differentiation. Deficiency of ID2 in BMDCs led to downregulation of KDR, suppression of proangiogenic myeloid cells, and prevention of low-grade to high-grade transition. Tumor-secreted TGF-β and granulocyte-macrophage CSF (GM-CSF) enhanced the KDR/ID2 signaling axis in BMDCs. Our results suggest that modulation of KDR/ID2 signaling may restrict tumor-associated myeloid cells and could potentially be a therapeutic strategy for preventing transformation of premalignant gliomas.
Yujie Huang, Prajwal Rajappa, Wenhuo Hu, Caitlin Hoffman, Babacar Cisse, Joon-Hyung Kim, Emilie Gorge, Rachel Yanowitch, William Cope, Emma Vartanian, Raymond Xu, Tuo Zhang, David Pisapia, Jenny Xiang, Jason Huse, Irina Matei, Hector Peinado, Jacqueline Bromberg, Eric Holland, Bi-sen Ding, Shahin Rafii, David Lyden, Jeffrey Greenfield
Controlled angiogenesis and lymphangiogenesis are essential for tissue development, function, and repair. However, aberrant neovascularization is an essential pathogenic mechanism in many human diseases, including diseases involving tumor growth and survival. Here, we have demonstrated that mice deficient in C-type lectin family 14 member A (CLEC14A) display enhanced angiogenic sprouting and hemorrhage as well as enlarged jugular lymph sacs and lymphatic vessels. CLEC14A formed a complex with VEGFR-3 in endothelial cells (ECs), and CLEC14A KO resulted in a marked reduction in VEGFR-3 that was concomitant with increases in VEGFR-2 expression and downstream signaling. Implanted tumor growth was profoundly reduced in CLEC14A-KO mice compared with that seen in WT littermates, but tumor-bearing CLEC14A-KO mice died sooner. Tumors in CLEC14A-KO mice had increased numbers of nonfunctional blood vessels and severe hemorrhaging. Blockade of VEGFR-2 signaling suppressed these vascular abnormalities and enhanced the survival of tumor-bearing CLEC14A-KO mice. We conclude that CLEC14A acts in vascular homeostasis by fine-tuning VEGFR-2 and VEGFR-3 signaling in ECs, suggesting its relevance in the pathogenesis of angiogenesis-related human disorders.
Sungwoon Lee, Seung-Sik Rho, Hyojin Park, Jeong Ae Park, Jihye Kim, In-Kyu Lee, Gou Young Koh, Naoki Mochizuki, Young-Myeong Kim, Young-Guen Kwon
Different tumor microenvironments (TMEs) induce stromal cell plasticity that affects tumorigenesis. The impact of TME-dependent heterogeneity of tumor endothelial cells (TECs) on tumorigenesis is unclear. Here, we isolated pure TECs from human colorectal carcinomas (CRCs) that exhibited TMEs with either improved (Th1-TME CRCs) or worse clinical prognosis (control-TME CRCs). Transcriptome analyses identified markedly different gene clusters that reflected the tumorigenic and angiogenic activities of the respective TMEs. The gene encoding the matricellular protein SPARCL1 was most strongly upregulated in Th1-TME TECs. It was also highly expressed in ECs in healthy colon tissues and Th1-TME CRCs but low in control-TME CRCs. In vitro, SPARCL1 expression was induced in confluent, quiescent ECs and functionally contributed to EC quiescence by inhibiting proliferation, migration, and sprouting, whereas siRNA-mediated knockdown increased sprouting. In human CRC tissues and mouse models, vessels with SPARCL1 expression were larger and more densely covered by mural cells. SPARCL1 secretion from quiescent ECs inhibited mural cell migration, which likely led to stabilized mural cell coverage of mature vessels. Together, these findings demonstrate TME-dependent intertumoral TEC heterogeneity in CRC. They further indicate that TEC heterogeneity is regulated by SPARCL1, which promotes the cell quiescence and vessel homeostasis contributing to the favorable prognoses associated with Th1-TME CRCs.
Elisabeth Naschberger, Andrea Liebl, Vera S. Schellerer, Manuela Schütz, Nathalie Britzen-Laurent, Patrick Kölbel, Ute Schaal, Lisa Haep, Daniela Regensburger, Thomas Wittmann, Ludger Klein-Hitpass, Tilman T. Rau, Barbara Dietel, Valérie S. Méniel, Alan R. Clarke, Susanne Merkel, Roland S. Croner, Werner Hohenberger, Michael Stürzl
Angiopoietin-2 (ANG2) regulates blood vessel remodeling in many pathological conditions through differential effects on Tie2 signaling. While ANG2 competes with ANG1 to inhibit Tie2, it can paradoxically also promote Tie2 phosphorylation (p-Tie2). A related paradox is that both inactivation and overactivation of Tie2 can result in vascular remodeling. Here, we reconciled these opposing actions of ANG2 by manipulating conditions that govern its actions in the vasculature. ANG2 drove vascular remodeling during
Minah Kim, Breanna Allen, Emilia A. Korhonen, Maximilian Nitschké, Hee Won Yang, Peter Baluk, Pipsa Saharinen, Kari Alitalo, Christopher Daly, Gavin Thurston, Donald M. McDonald
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