Lack of Protein S in mice causes embryonic lethal coagulopathy and vascular dysgenesis
Tal Burstyn-Cohen, … , Mary Jo Heeb, Greg Lemke
Tal Burstyn-Cohen, … , Mary Jo Heeb, Greg Lemke
Published September 1, 2009
Citation Information: J Clin Invest. 2009;119(10):2942-2953. https://doi.org/10.1172/JCI39325.
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Research Article Vascular biology

Lack of Protein S in mice causes embryonic lethal coagulopathy and vascular dysgenesis

Abstract

Protein S (ProS) is a blood anticoagulant encoded by the Pros1 gene, and ProS deficiencies are associated with venous thrombosis, stroke, and autoimmunity. These associations notwithstanding, the relative risk that reduced ProS expression confers in different disease settings has been difficult to assess without an animal model. We have now described a mouse model of ProS deficiency and shown that all Pros1–/– mice die in utero, from a fulminant coagulopathy and associated hemorrhages. Although ProS is known to act as a cofactor for activated Protein C (aPC), plasma from Pros1+/– heterozygous mice exhibited accelerated thrombin generation independent of aPC, and Pros1 mutants displayed defects in vessel development and function not seen in mice lacking protein C. Similar vascular defects appeared in mice in which Pros1 was conditionally deleted in vascular smooth muscle cells. Mutants in which Pros1 was deleted specifically in hepatocytes, which are thought to be the major source of ProS in the blood, were viable as adults and displayed less-severe coagulopathy without vascular dysgenesis. Finally, analysis of mutants in which Pros1 was deleted in endothelial cells indicated that these cells make a substantial contribution to circulating ProS. These results demonstrate that ProS is a pleiotropic anticoagulant with aPC-independent activities and highlight new roles for ProS in vascular development and homeostasis.

Authors

Tal Burstyn-Cohen, Mary Jo Heeb, Greg Lemke

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Figure 6

Immunohistochemical analysis of embryonic vasculature.

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Immunohistochemical analysis of embryonic vasculature. (A and B) Section...
(A and B) Sections of dorsal superficial artery stained with the smooth muscle cell marker α-SMA. Vessels are delineated by dashed lines. VSMCs show intense α-SMA staining throughout the circumference of the WT vessel (A) but only weak noncontinuous staining in the Pros1–/– vessel (B). (C and D) Double staining of ECs with CD144/VE-cadherin (green) and VSMCs with α-SMA (red). (C) WT arterioles have a luminal EC layer surrounded by a VSMC layer. (D) Pros1–/– arteriole shows only residual α-SMA signal and disorganized, nonuniform endothelial and VSMC marker staining. (E and F) Double staining of spinal cord microvasculature for CD31/PECAM-1 (green) and fibrin (red). (E) WT small-diameter vessels (apposed arrowheads) without fibrin clots. (F) Pros1–/– spinal cord vasculature with fibrin-positive immunoreactivity within vessels and aneurysms (apposed arrowheads). (G and H) Vessel ECs revealed by CD144/VE-cadherin in brain vasculature. (G) WT tissue shows elongated and uniform vessels, with tight interendothelial junctions. (H) Pros1–/– mice fail to form tight vessels, with ECs dispersed in clusters. (I and J) Yolk sac vasculature. Blood-filled vessels are seen in WT (I) but not in Pros1–/– yolk sac (J). (K and L) PECAM-1/CD31 immunoreactivity in yolk sac. CD31 staining reveals an intricate vascular network in WT yolk sac (K), but Pros1–/– yolk sac vasculature shows reduced vascular density, smaller-caliber vessels, and blind ends that fail to anastomose (asterisks). Scale bar in L applies to all panels: 150 μm in A, B, E, F, K, and L; 40 μm in C, D, G, and H; 500 μm in I and J.