Endothelial cell O-glycan deficiency causes blood/lymphatic misconnections and consequent fatty liver disease in mice
Jianxin Fu, … , Florea Lupu, Lijun Xia
Jianxin Fu, … , Florea Lupu, Lijun Xia
Published October 16, 2008
Citation Information: J Clin Invest. 2008;118(11):3725-3737. https://doi.org/10.1172/JCI36077.
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Research Article Vascular biology

Endothelial cell O-glycan deficiency causes blood/lymphatic misconnections and consequent fatty liver disease in mice

Abstract

Mucin-type O-glycans (O-glycans) are highly expressed in vascular ECs. However, it is not known whether they are important for vascular development. To investigate the roles of EC O-glycans, we generated mice lacking T-synthase, a glycosyltransferase encoded by the gene C1galt1 that is critical for the biosynthesis of core 1–derived O-glycans, in ECs and hematopoietic cells (termed here EHC T-syn–/– mice). EHC T-syn–/– mice exhibited embryonic and neonatal lethality associated with disorganized and blood-filled lymphatic vessels. Bone marrow transplantation and EC C1galt1 transgene rescue demonstrated that lymphangiogenesis specifically requires EC O-glycans, and intestinal lymphatic microvessels in EHC T-syn–/– mice expressed a mosaic of blood and lymphatic EC markers. The level of O-glycoprotein podoplanin was significantly reduced in EHC T-syn–/– lymphatics, and podoplanin-deficient mice developed blood-filled lymphatics resembling EHC T-syn–/– defects. In addition, postnatal inactivation of C1galt1 caused blood/lymphatic vessel misconnections that were similar to the vascular defects in the EHC T-syn–/– mice. One consequence of eliminating T-synthase in ECs and hematopoietic cells was that the EHC T-syn–/– pups developed fatty liver disease, because of direct chylomicron deposition via misconnected portal vein and intestinal lymphatic systems. Our studies therefore demonstrate that EC O-glycans control the separation of blood and lymphatic vessels during embryonic and postnatal development, in part by regulating podoplanin expression.

Authors

Jianxin Fu, Holger Gerhardt, J. Michael McDaniel, Baoyun Xia, Xiaowei Liu, Lacramioara Ivanciu, Annelii Ny, Karlien Hermans, Robert Silasi-Mansat, Samuel McGee, Emma Nye, Tongzhong Ju, Maria I. Ramirez, Peter Carmeliet, Richard D. Cummings, Florea Lupu, Lijun Xia

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Figure 3

EHC T-syn–/– mice have abnormal connections between blood and lymphatic vessels.

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EHC T-syn–/– mice develop hybrid vessels that have a mosaic expression o...
(A) Whole-mount confocal imaging of E17.5 intestinal microvascular networks. A mAb against CD31 marks both blood and lymphatic vessels, and anti–Lyve-1 stains lymphatic vessels. Arrows indicate blood capillaries. (B) Overlaid confocal and phase contrast images demonstrate a blood-filled EHC T-syn–/– lymphatic vessel. Asterisks mark blood cells. Arrow marks lymphatic endothelium. (C) Microvascular networks of intestinal villi stained with anti–Lyve-1. The mice were arterially injected with dextran-FITC (150 kDa) prior to the confocal analysis. The arrow indicates a dextran-FITC–filled EHC T-syn–/– lacteal. (D) Confocal imaging of lacteals. The mice were injected with 1-μm fluorescent beads (red) prior to the analysis. Arrows indicate beads. (E) Confocal images of intestinal cryosections with antibodies against CD31, α-SMA, and Lyve-1. Arrowheads indicate smooth muscle cells in lamina propria. Asterisks indicate ectopic smooth muscle cell staining. (F) Confocal images of intestinal cryosections with antibodies against CD31, α-SMA, and Prox1. Asterisks indicate ectopic smooth muscle cell staining. Arrows mark Prox1 staining. Scale bars: 20 μm. Mice were 3–6 weeks old unless otherwise specified.