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A murine fibroblast growth factor (FGF) receptor expressed in CHO cells is activated by basic FGF and Kaposi FGF
A Mansukhani1, D Moscatelli, D Talarico
1Department of Microbiology, New York University School of Medicine, NY 10016.
Abstract:
We have cloned a murine cDNA encoding a tyrosine kinase receptor with about 90% similarity to the chicken fibroblast growth factor (FGF) receptor and the human fms-like gene (FLG) tyrosine kinase. This mouse receptor lacks 88 amino acids in the extracellular portion, leaving only two immunoglobulin-like domains compared to three in the chicken FGF receptor. The cDNA was cloned into an expression vector and transfected into receptor-negative CHO cells. We show that cells expressing the receptor can bind both basic FGF and Kaposi FGF. Although the receptor binds basic FGF with a 15- to 20-fold higher affinity, Kaposi FGF is able to induce down-regulation of the receptor to the same extent as basic FGF. The receptor is phosphorylated upon stimulation with both FGFs, DNA synthesis is stimulated, and a proliferative response is produced in cells expressing the receptor, whereas cells expressing the cDNA in the antisense orientation show none of these responses to basic FGF or Kaposi FGF. Thus this receptor can functionally interact with two growth factors of the FGF family.
Insights
Researchers identified a novel mouse tyrosine kinase receptor that binds and responds to two fibroblast growth factors (FGFs). This discovery advances understanding of FGF signaling pathways and receptor function.
Area of Science:
- Molecular Biology
- Cell Signaling
- Receptor Tyrosine Kinases
Background:
- Fibroblast growth factors (FGFs) are crucial regulators of cellular processes.
- Tyrosine kinase receptors play key roles in cell growth and differentiation.
- Existing FGF receptors exhibit varying domain structures and ligand specificities.
Purpose of the Study:
- To clone and characterize a novel murine tyrosine kinase receptor.
- To investigate the functional interaction of this receptor with different FGFs.
- To determine the downstream signaling events triggered by FGF binding.
Main Methods:
- Cloning of a murine cDNA encoding a tyrosine kinase receptor.
- Transfection of the cDNA into receptor-negative Chinese hamster ovary (CHO) cells.
- Binding assays with basic FGF and Kaposi FGF.
- Analysis of receptor phosphorylation, DNA synthesis, and cell proliferation.
Main Results:
- The cloned receptor shares high similarity with chicken FGF receptor and human FLG tyrosine kinase.
- The mouse receptor binds both basic FGF and Kaposi FGF, with higher affinity for basic FGF.
- Both FGFs induce receptor phosphorylation, DNA synthesis, and proliferation in transfected cells.
- Antisense orientation transfection abolished these responses, confirming receptor specificity.
Conclusions:
- The novel murine receptor functionally interacts with both basic and Kaposi FGF.
- This receptor is capable of mediating FGF-induced cellular responses.
- The findings contribute to understanding the diversity and function of FGF receptor family members.