Related Experiment Videos
Involvement of basic fibroblast growth factor NH2 terminus in nuclear accumulation
1Institut Louis Bugnard, Institut National de la Santé et la Recherche Médicale Unité 397, CHU Rangueil, Toulouse, France.
Growth Factors (Chur, Switzerland)
|January 1, 1994
Summary
The human basic Fibroblast Growth Factor (bFGF) gene produces multiple protein forms. The 210-amino acid bFGF isoform preferentially accumulates in the nucleus, enhancing plasminogen activator activity.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- The human basic Fibroblast Growth Factor (bFGF) gene encodes multiple protein isoforms through alternative initiation codon usage.
- Understanding the intracellular fate and localization of these bFGF isoforms is crucial for elucidating their distinct biological functions.
Purpose of the Study:
- To comparatively analyze the intracellular localization and bioactivity of different human bFGF isoforms.
- To investigate the mechanisms underlying the nuclear accumulation of specific bFGF variants.
Main Methods:
- Production and purification of various bFGF isoforms (210, 155, and 146 amino acids) in E. coli.
- Cellular uptake and intracellular localization studies using fluorescently labeled bFGF.
- Construction and analysis of a chimeric protein (SVbFGF) to assess the role of the nuclear localization sequence (NLS).
- Assessment of bioactivities, including mitogenic effects and stimulation of plasminogen activator, on adult bovine aortic endothelial (ABAE) cells.
Main Results:
- All bFGF isoforms were internalized by cells with similar efficiency.
- The 210-amino acid bFGF isoform showed significantly higher nuclear accumulation (36%) compared to other isoforms (15%).
- A chimeric protein (SVbFGF) lacking the NLS did not exhibit altered nuclear accumulation, suggesting NLS-independent nuclear import.
- The 210-amino acid bFGF isoform demonstrated enhanced stimulation of plasminogen activator, correlating with its nuclear accumulation.
- Degradation pathways, mitogenic activity, and rRNA synthesis stimulation were comparable across all bFGF isoforms.
Conclusions:
- The amino-terminal region of the 210-amino acid bFGF isoform contains a sequence responsible for its nuclear retention.
- Nuclear accumulation of exogenous bFGF is not solely mediated by NLS-associated functions.
- Specific bFGF isoforms exhibit distinct intracellular localization and differential bioactivity, particularly in stimulating plasminogen activator, which is linked to nuclear localization.