Localization of anticoagulantly active heparan sulfate proteoglycans in vascular endothelium: Antithrombin binding on cultured endothelial cells and perfused rat aorta

Journal Article · Sat Sep 01 00:00:00 EDT 1990 · Journal of Cell Biology; (USA)

DOI:https://doi.org/10.1083/jcb.111.3.1293· OSTI ID:6370103

de Agostini, A I; Watkins, S C; Slayter, H S; Youssoufian, H; Rosenberg, R D ^[1]

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1. Massachusetts Institute of Technology, Cambridge (USA)

We have studied the interaction of {sup 125}I-antithrombin ({sup 125}I-AT) with microvascular endothelial cells (RFPEC) to localize the cellular site of anticoagulantly active heparan sulfate proteoglycans (HSPG). The radiolabeled protease inhibitor bound specifically to the above HSPG with a Kd of approximately 50 nM. Confluent monolayer RFPEC cultures exhibited a linear increase in the amount of AT bound per cell for up to 16 d, whereas suspension RFPEC cultures possessed a constant number of protease inhibitor binding sites per cell for up to 5 d. These results suggest that monolayer RFPEC cultures secrete anticoagulantly active HSPG, which then accumulate in the extracellular matrix. This hypothesis was confirmed by quantitative light and EM level autoradiography which demonstrated that the AT binding sites are predominantly located in the extracellular matrix with only small quantities of protease inhibitor complexed to the cell surface. We have also pinpointed the in vivo position of anticoagulantly active HSPG within the blood vessel wall. Rat aortas were perfused, in situ, with {sup 125}I-AT, and bound labeled protease inhibitor was localized by light and EM autoradiography. The anticoagulantly active HSPG were concentrated immediately beneath the aortic and vasa vasorum endothelium with only a very small extent of labeling noted on the luminal surface of the endothelial cells. Based upon the above data, we propose a model whereby luminal and abluminal anticoagulantly active HSPG regulate coagulation mechanism activity.

• OSTI ID: 6370103
• Journal Information: Journal of Cell Biology; (USA), Vol. 111:3; ISSN 0021-9525
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ANTICOAGULANTS
BIOCHEMICAL REACTION KINETICS
GLYCOPROTEINS
BIOLOGICAL LOCALIZATION
AORTA
AUTORADIOGRAPHY
CELL MEMBRANES
ENDOTHELIUM
ENZYME INHIBITORS
IODINE 125
PERFUSED TISSUES
RATS
ANIMAL TISSUES
ANIMALS
ARTERIES
BETA DECAY RADIOISOTOPES
BLOOD VESSELS
BODY
CARDIOVASCULAR SYSTEM
CELL CONSTITUENTS
DAYS LIVING RADIOISOTOPES
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
HEMATOLOGIC AGENTS
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPES
KINETICS
MAMMALS
MEMBRANES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RODENTS
TISSUES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques