Generation and phenotypic analysis of protein S–deficient mice

Abstract

Protein S (PS) is an important natural anticoagulant with potentially multiple biologic functions. To investigate further the role of PS in vivo, we generated Pros ؉/؊ heterozygous mice. In the null (؊) allele, the Pros exons 3 to 7 have been excised through conditional gene targeting. Pros ؉/؊ mice did not present any signs of spontaneous thrombosis and had reduced PS plasma levels and activated protein C cofactor activity in plasma coagulation and thrombin generation assays. Tissue factor pathway inhibitor cofactor activity of PS could not be demonstrated. Heterozygous Pros ؉/؊ mice exhibited a notable thrombotic phenotype in vivo when challenged in a tissue factor-induced thromboembolism model. No viable Pros ؊/؊ mice were obtained through mating of Pros ؉/؊ parents. Most E17.5 Pros ؊/؊ embryos were found dead with severe intracranial hemorrhages and most likely presented consumptive coagulopathy, as demonstrated by intravascular and interstitial fibrin deposition and an increased number of megakaryocytes in the liver, suggesting peripheral thrombocytopenia. A few E17.5 Pros ؊/؊ embryos had less severe phenotype, indicating that life-threatening manifestations might occur between E17.5 and the full term. Thus, similar to human phenotypes, mild heterozygous PS deficiency in mice was associated with a thrombotic phenotype, whereas total homozygous deficiency in PS was incompatible with life.

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

“…These mutant lines display blood coagulation defects very similar to those we describe. Consistent with our data, the Pros1 +/-heterozygotes also show enhanced sensitivity to tissue factor-induced venous thromboembolism (55).…”

The protein C pathway in tissue inflammation and injury: pathogenic role and therapeutic implications

“…119,120 PS Ϫ/Ϫ offspring generated from matings of PS ϩ/Ϫ males and females also die neonatally, 121 thus offering another demonstration that defects in the natural anticoagulation system lead to adverse effects on pregnancy.…”

Targeted mutagenesis of zebrafish antithrombin III triggers disseminated intravascular coagulation and thrombosis, revealing insight into function

“…1 However, mouse knockout models display more severe phenotypes, with neonatal and embryonic loss for PROC and PROS1 deficiency, respectively. [2][3][4] Complete loss of AT3 has not been described in humans, and is presumed to be in utero lethal. 1 This is supported by the observation that homozygous deletion of AT3 in mice results in prenatal lethality, with widespread fibrin deposition in the heart and liver.…”