Protein S is a key component for the regulation of hemostasis. Protein S serves as a cofactor for activated Protein C, an enzyme responsible for the degradation of two protein elements of the blood coagulation pathway. Consequently, Protein S through the action of Protein C down-regulates the blood clotting process. Individuals deficient in functional Protein S, either because of genetic or environmentally-acquired reasons, are at a higher risk of experiencing thrombotic disorders. Symptoms commonly associated with Protein S deficiency include thrombophlebitis, deep vein thrombosis, and pulmonary emboli. At the present time the genetic basis of Protein S deficiency and its relationship to thrombosis are unknown. The long-term objective of the proposed research is to understand the genetic basis of Protein S deficiency and thrombosis. This will be accomplished, in part, through the proposed studies, designed to provide a better understanding of the normal and abnormal Protein S genes and the functional properties of the Protein S products.
Specific aims and methods for achieving these goals include: a) characterization of gaps in introns A, C and I of the expressed Protein S gene (PS-alpha), using PCR amplification and confirmation by genomic Southern hybridization; b.) cloning and characterization by DNA sequencing and Southern mapping of the PS-alpha gene from genetically Protein S deficient individuals; c) site-directed mutagenesis and mammalian cell expression studies to address structure/function relationships relating to the role(s) of N-glycosylation for Protein S. Comparative studies with deglycosylated plasma-derived Protein S will also be performed; and d) isolation and characterization with conventional biochemical methods of a plasma component that reduces the interaction between Protein S and C4b-binding protein. The results of these studies will lead to a better understanding of the structure and function of Protein S; and may eventually lead to improved methods of diagnosis and therapy for patients having Protein S deficiency and resulting thrombotic disorders.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
2R01HL038899-06
Application #
3355353
Study Section
Medical Biochemistry Study Section (MEDB)
Project Start
1987-07-01
Project End
1996-06-30
Budget Start
1992-07-01
Budget End
1993-06-30
Support Year
6
Fiscal Year
1992
Total Cost
Indirect Cost
Name
University of Vermont & St Agric College
Department
Type
Schools of Medicine
DUNS #
066811191
City
Burlington
State
VT
Country
United States
Zip Code
05405
Lu, D; Xie, R L; Rydzewski, A et al. (1997) The effect of N-linked glycosylation on molecular weight, thrombin cleavage, and functional activity of human protein S. Thromb Haemost 77:1156-63
Li, M; Long, G L (1996) Identification of two novel point mutations in the human protein S gene associated with familial protein S deficiency and thrombosis. Arterioscler Thromb Vasc Biol 16:1407-15
Rydzewski, A; Myyyliwiec, M; Long, G L (1996) Construction, expression and preliminary characterization of glycosylation mutants of human protein S. Pol J Pharmacol 48:197-201
Lu, D; Schmidel, D K; Long, G L (1994) Structure of mouse protein S as determined by PCR amplification and DNA sequencing of cDNA. Thromb Res 74:135-42
Long, G L; Tomczak, J A; Rainville, I R et al. (1994) Homozygous type I protein C deficiency in two unrelated families exhibiting thrombophilia related to Ala136-->Pro or Arg286-->His mutations. Thromb Haemost 72:526-33
Nelson, R M; Long, G L (1992) Binding of protein S to C4b-binding protein. Mutagenesis of protein S. J Biol Chem 267:8140-5
Schmidel, D K; Nelson, R M; Broxson Jr, E H et al. (1991) A 5.3-kb deletion including exon XIII of the protein S alpha gene occurs in two protein S-deficient families. Blood 77:551-9
Villarreal, X C; Grant, B W; Long, G L (1991) Demonstration of osteonectin mRNA in megakaryocytes: the use of the polymerase chain reaction. Blood 78:1216-22
Nelson, R M; VanDusen, W J; Friedman, P A et al. (1991) beta-Hydroxyaspartic acid and beta-hydroxyasparagine residues in recombinant human protein S are not required for anticoagulant cofactor activity or for binding to C4b-binding protein. J Biol Chem 266:20586-9
Nelson, R M; Long, G L (1991) Solution-phase equilibrium binding interaction of human protein S with C4b-binding protein. Biochemistry 30:2384-90

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