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Density-dependent accumulation of basic fibroblast growth factor in the subendothelial matrix
1Program in Cell, Molecular and Developmental Biology, Tufts University Health Science Schools, Boston, MA 02111.
European Journal of Cell Biology
|October 1, 1992
Summary
Basic fibroblast growth factor (bFGF) accumulates in the subendothelial matrix with endothelial cell contact, influenced by proteoglycans and heparin. This process may impact vascular remodeling and angiogenesis.
Area of Science:
- Cell Biology
- Biochemistry
- Vascular Biology
Background:
- Basic fibroblast growth factor (bFGF) is found in the subendothelial matrix but its release and deposition mechanisms are unclear.
- bFGF lacks a conventional signal sequence, making its extracellular localization intriguing.
Purpose of the Study:
- To investigate the cellular and subcellular mechanisms of bFGF release and subendothelial matrix sequestration.
- To determine if bFGF accumulation depends on endothelial cell (EC) contact and growth arrest.
Main Methods:
- Generated polyclonal antibodies against chemically cross-linked bFGF.
- Utilized 3T3 cell proliferation assays, enzyme immunoassays, and immunofluorescence.
- Examined bFGF localization in endothelial cells under varying confluency and treatment conditions (cycloheximide, beta-D xyloside, heparin).
Main Results:
- Extracellular matrix bFGF was detected in confluent EC cultures but not subconfluent ones.
- Cycloheximide abolished extracellular bFGF staining; beta-D xyloside and heparin reduced matrix-associated bFGF by 40%.
- beta-D xyloside treatment increased bFGF activity in conditioned media and nuclear localization was observed under specific fixation/lysis conditions.
Conclusions:
- bFGF accumulates in the proteoglycan-rich subendothelial matrix with EC-cell contact formation.
- Microvascular matrix composition and cellular phenotype may influence bFGF accumulation.
- This accumulation could play a role in vascular morphogenesis and remodeling during angiogenesis.