Related Experiment Video
Updated: Aug 23, 2026

Automated Imaging and Analysis for the Quantification of Fluorescently Labeled Macropinosomes
Published on: August 24, 2021
Fibroblast growth factor 2 endocytosis in endothelial cells proceed via syndecan-4-dependent activation of Rac1 and a
Eugene Tkachenko1, Esther Lutgens, Radu-Virgil Stan
1Angiogenesis Research Center, Department of Medicine, Dartmouth Medical School, One Medical Center Drive, Lebanon, NH 03756, USA.
Abstract:
Full activity of fibroblast growth factors (FGFs) requires their internalization in addition to the interaction with cell surface receptors. Recent studies have suggested that the transmembrane proteoglycan syndecan-4 functions as a FGF2 receptor. In this study we investigated the molecular basis of syndecan endocytosis and its role in FGF2 internalization in endothelial cells. We found that syndecan-4 uptake, induced either by treatment with FGF2 or by antibody clustering, requires the integrity of plasma membrane lipid rafts for its initiation, occurs in a non-clathrin-, non-dynamin-dependent manner and involves Rac1, which is activated by syndecan-4 clustering. FGF2 was internalized in a complex with syndecan-4 in 70 kDa dextran-containing endocytic vesicles. FGF2 and syndecan-4 but not dextran endocytosis were blocked by the dominant negative Rac1 while amiloride and the dominant-negative Cdc42 blocked internalization of dextran in addition to FGF2 and syndecan-4. Taken together, these results demonstrate that FGF2 endocytosis requires syndecan-4 clustering-dependent activation of Rac1 and the intact CDC42-dependent macropinocytic pathway.
Related Concept Videos
Intracellular Signaling Affects Focal Adhesions
Some...
Regulation of Angiogenesis and Blood Supply
Mechanism of Lamellipodia Formation
Small GTPases - Ras and Rho
Three regulatory proteins control their activity:
Mechanism of Filopodia Formation
Their main function is to guide migrating cells during normal tissue morphogenesis or cancer metastasis by recognizing and making initial contacts with the extracellular matrix. However, they can also act as stationary cell anchors or help to establish communication...
TGF - β Signaling Pathway

