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Permeable FGF-1 nuclear localization signal peptide stimulates DNA synthesis in various cell types but is
1Biosignaling Department, National Institute of Bioscience and Human Technology, 1-1 Higashi, Tsukuba, Ibaraki, 305-8566, Japan.
Abstract:
An earlier report indicated that a 26-amino-acid peptide (SA), comprised of the nuclear localization signal (NLS) of fibroblast growth factor-1 (FGF-1) and a membrane-permeable peptide, was able to stimulate DNA synthesis after it was taken up by NIH3T3 fibroblasts. Here, we report that SA, but not a mutant with the NLS motif destroyed, induced DNA synthesis in BALB/c3T3 murine fibroblasts, human vascular endothelial (HUVE) cells, and primary cultured hepatocytes, although the activity was weaker than that of FGF-1. The kinetics of SA-induced DNA synthesis and G1 cyclin expression were similar to those elicited by FGF-1, indicating that SA induces cell cycle progression. Kinetic analysis also suggested that SA stimulates only a fraction of the DNA replication in BALB/c3T3 cells. At high cell densities, SA-induced G1 cyclin expression and DNA synthesis were more strongly inhibited than those induced by FGF-1. SA did not induce cell division in HUVE and BALB/c3T3 cells and did not interfere with FGF-1-stimulated proliferation of HUVE cells. These results indicate that SA is able to partially induce cell cycle progression through a contact-inhibition sensitive signaling pathway, but it is insufficient to support cell mitosis. We also suggest that signaling by SA does not interfere with that of FGF-1.
Insights
A peptide containing a nuclear localization signal (NLS) partially induces DNA synthesis and cell cycle progression in various cells. However, it does not cause cell division and is insufficient for mitosis.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- A previously identified 26-amino-acid peptide (SA), containing the nuclear localization signal (NLS) of fibroblast growth factor-1 (FGF-1) and a membrane-permeable sequence, was shown to stimulate DNA synthesis in NIH3T3 fibroblasts.
- The mechanism by which SA influences cellular processes, particularly cell cycle progression and mitosis, requires further investigation.
Purpose of the Study:
- To investigate the ability of the SA peptide to induce DNA synthesis and cell cycle progression in different cell types.
- To compare the effects of SA with those of FGF-1 on cellular processes.
- To determine if SA can induce cell division or interfere with FGF-1-stimulated proliferation.
Main Methods:
- Treatment of BALB/c3T3 murine fibroblasts, human vascular endothelial (HUVE) cells, and primary cultured hepatocytes with the SA peptide.
- Assessment of DNA synthesis and G1 cyclin expression kinetics.
- Evaluation of SA's effect on cell division and FGF-1-stimulated proliferation.
- Utilizing a mutant SA peptide with a destroyed NLS motif as a control.
Main Results:
- The SA peptide, but not its NLS-mutant, induced DNA synthesis in BALB/c3T3, HUVE, and primary hepatocytes, albeit with weaker activity than FGF-1.
- SA-induced DNA synthesis and G1 cyclin expression kinetics mirrored those of FGF-1, indicating cell cycle progression.
- SA induced only a fraction of the DNA replication in BALB/c3T3 cells and its effects were more sensitive to contact inhibition than FGF-1.
- SA did not induce cell division in HUVE and BALB/c3T3 cells and did not impede FGF-1-stimulated HUVE cell proliferation.
Conclusions:
- SA partially induces cell cycle progression via a contact-inhibition sensitive pathway.
- SA is insufficient to support cell mitosis.
- SA-mediated signaling does not interfere with FGF-1 signaling.