Carbohydrate-binding protein CLEC14A regulates VEGFR-2– and VEGFR-3–dependent signals during angiogenesis and lymphangiogenesis
Sungwoon Lee, … , Young-Myeong Kim, Young-Guen Kwon
Sungwoon Lee, … , Young-Myeong Kim, Young-Guen Kwon
Published February 1, 2017; First published December 19, 2016
Citation Information: J Clin Invest. 2017;127(2):457-471. https://doi.org/10.1172/JCI85145.
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Categories: Research Article Angiogenesis Vascular biology

Carbohydrate-binding protein CLEC14A regulates VEGFR-2– and VEGFR-3–dependent signals during angiogenesis and lymphangiogenesis

Abstract

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.

Authors

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

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Figure 1

CLEC14A is specifically expressed in blood and lymphatic ECs, and loss of CLEC14A increases developmental angiogenesis and lymphangiogenesis.

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CLEC14A is specifically expressed in blood and lymphatic ECs, and loss o...
(A) Images of unfixed E13.5 yolk sacs from WT and CLEC14A-KO mice. n = 10 per group. Scale bar: 200 μm. (B) Whole-mount CD31 immunostaining of yolk sacs from WT and CLEC14A-KO mice. n = 10 per group. Scale bars: 100 μm. (C) Quantification of CD31 immunostaining of E13.5 yolk sacs (percentage of control). (D) Lateral and dorsal views of unfixed E13.5 WT and CLEC14A-KO embryos. n = 10 per group. Scale bars: 100 μm. (E) Immunostaining of flat-mount preparations of E13.5 hind brains from WT and CLEC14A-KO mice. Each layer of vessels in the hind brain is displayed according to the radial position. n = 6 per group. Scale bars: 100 μm. (F) Whole-mount preparations of P5 retinae from WT and CLEC14A-KO pups immunostained for CD31 (white dots represent individual filopodia). n = 10 per group. Scale bars: 100 μm. (G) Quantification of relative vascular density (percentage of control). (H) Transverse sections of E15.5 WT and CLEC14A-KO embryos immunostained for CD31 and LYVE-1. n = 6 per group. Scale bars: 100 μm. JLS: Jugular Lymph Sac. (I and J) Quantification of relative vascular density and diameter of JLS (percentage of control) (K) Flat-mount preparations of E15.5 WT and CLEC14A-KO forelimbs immunostained for CD31 and LYVE-1. n = 6 per group. Scale bars: 100 μm. (L and M) Quantification of relative lymphatic vessel density and diameter of the lymphatic vessels (percentage of control). All experiments were repeated on at least 6 different sets of WT and KO littermates. *P < 0.05, **P < 0.005, and ***P < 0.0001, by paired, 2-tailed Student’s t test. Error bars represent the mean ± SD.