TRANSFORMING GROWTH FACTOR-BETA-1-SPECIFIC BINDING-PROTEINS ON HUMAN VASCULAR ENDOTHELIAL-CELLS

Transforming growth factor β (TGFβ) regulates the growth of human umbilical vein endothelial cells (HUVEC) differently depending on the isoform of TGFβ and the culture conditions. The cells are resistant to growth inhibition by TGFβ when the cells are cultured on substratum coated with gelatin. However, the proliferation of HUVEC cultured on substratum without a gelatin coating is inhibited by TGFβ, depending on the isoform and concentration of TGFβ. Binding assays with 125I-TGFβ1 reveal that HUVEC contain a single class of high-affinity (Kd = 4.4 pM) TGFβ1 binding sites with 8500 sites per cell. Affinity cross-linking studies demonstrate that HUVEC express 180 and 80 kDa TGFβ1 binding sites that do not bind TGFβ2. The reduction and the removal of glycosaminoglycans does not affect the electrophoretic mobility of the 180-kDa binding protein cross-linked with 125I-TGFβ1. Therefore, the 180-kDa TGFβ1 binding protein is not related to the type III TGFβ receptor, but might be a novel TGFβ1-specific receptor/binding protein expressed on vascular endothelial cells. The expression of TGFβ1 binding sites is not affected by the presence or absence of the gelatin coating on the culture substratum. The data suggest that a gelatin coating does not regulate the susceptibility of HUVEC to TGFβ1 at the level of the receptor/binding proteins, and that growth inhibition of HUVEC by TGFβ1 is linked to the regulation of extracellular matrices required for the interaction between the cells and the substratum. © 1992.