Surface Binding and Internalization of Platelet-Derived Growth Factor in Human Fibroblasts

Surface binding and uptake of platelet-derived growth factor (PDGF) in human fibroblasts cultivated in vitro were studied by quantitative electron microscopic autoradiography using125I-labeled PDGF and by indirect immunofluorescence using PDGF antibodies. After 120 min at 12 degrees C PDGF was found...

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Published inProceedings of the National Academy of Sciences - PNAS Vol. 80; no. 18; pp. 5592 - 5596
Main Authors Nilsson, Jan, Thyberg, Johan, Heldin, Carl-Henrik, Westermark, Bengt, Wasteson, Ake
Format Journal Article
LanguageEnglish
Published United States National Academy of Sciences of the United States of America 01.09.1983
National Acad Sciences
Subjects
Autoradiography
Cell growth
Cell membranes
Cells
Cells, Cultured
electron microscopy
Electrons
Endocytosis
Fibroblasts
Fibroblasts - metabolism
Fluorescent Antibody Technique
Golgi apparatus
Growth Substances - metabolism
Humans
Internalization
Lysosomes
man
Microscopy, Electron
Neuroglia
Peptides - metabolism
plasma membranes
Platelet-Derived Growth Factor
Radioactive materials
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Summary:Surface binding and uptake of platelet-derived growth factor (PDGF) in human fibroblasts cultivated in vitro were studied by quantitative electron microscopic autoradiography using125I-labeled PDGF and by indirect immunofluorescence using PDGF antibodies. After 120 min at 12 degrees C PDGF was found preferentially in coated regions of the plasma membrane. Warming the cells to 37 degrees C initiated rapid ingestion of the factor via small vesicles, usually lacking a membrane coat. After 10 min PDGF started to appear in lysosomes, and it showed maximal concentration within these organelles after 30 min. There were also signs of passage of PDGF through the Golgi complex, but only after 60 min. Treatment of the cells with chloroquine, a weak base that inhibits intralysosomal degradation, prevented disappearance of tracer from the lysosomes. The observations indicate that PDGF was internalized via coated regions of the plasma membrane and carried to lysosomes for degradation. Subsequent appearance of tracer within the Golgi complex could reflect receptor-ligand complexes that escaped degradation and were recirculated back to the cell surface.
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ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.80.18.5592