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FGFR-4, a novel acidic fibroblast growth factor receptor with a distinct expression pattern
J Partanen1, T P Mäkelä, E Eerola
1Department of Virology, University of Helsinki, Finland.
Abstract:
We have previously identified two novel members of the fibroblast growth factor receptor (FGFR) gene family expressed in K562 erythroleukemia cells. Here we report cDNA cloning and analysis of one of these genes, named FGFR-4. The deduced amino acid sequence of FGFR-4 is 55% identical with both previously characterized FGFRs, flg and bek, and has the structural characteristics of a FGFR family member including three immunoglobulin-like domains in its extracellular part. Antibodies raised against the carboxy terminus of FGFR-4 detected 95 and 110 kd glycoproteins with a protein backbone of 88 kd in COS cells transfected with a FGFR-4 cDNA expression vector. The FGFR-4 protein expressed in COS cells could also be affinity-labeled with radioiodinated acidic FGF. Furthermore, ligand binding experiments demonstrated that FGFR-4 binds acidic FGF with high affinity but does not bind basic FGF. FGFR-4 is expressed as a 3.0 kb mRNA in the adrenal, lung, kidney, liver, pancreas, intestine, striated muscle and spleen tissues of human fetuses. The expression pattern of FGFR-4 is distinct from that of flg and bek and the yet additional member of the same gene family, FGFR-3, which we have also cloned from the K562 leukemia cells. Our results suggest that FGFR-4 along with other fibroblast growth factor receptors performs cell lineage and tissue-specific functions.
Insights
Researchers cloned and analyzed FGFR-4, a novel fibroblast growth factor receptor. This receptor binds acidic FGF and has distinct tissue expression, suggesting specific cell lineage functions.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Two novel fibroblast growth factor receptor (FGFR) family members were previously identified in K562 erythroleukemia cells.
- Fibroblast growth factor receptors play crucial roles in cell signaling and development.
Purpose of the Study:
- To report the cDNA cloning and characterization of one novel FGFR member, designated FGFR-4.
- To investigate the structural, functional, and expression characteristics of FGFR-4.
Main Methods:
- cDNA cloning and sequence analysis of FGFR-4.
- Antibody-based detection of FGFR-4 protein in transfected COS cells.
- Ligand binding assays using acidic and basic FGF.
- mRNA expression analysis in human fetal tissues.
Main Results:
- FGFR-4 shares 55% amino acid identity with known FGFRs (flg, bek) and possesses characteristic FGFR structural domains.
- FGFR-4 protein (95 and 110 kd glycoproteins) was detected in transfected COS cells and binds acidic FGF with high affinity.
- FGFR-4 mRNA (3.0 kb) is expressed in various human fetal tissues, with a distinct pattern compared to other FGFRs.
- FGFR-4 does not bind basic FGF.
Conclusions:
- FGFR-4 is a novel member of the FGFR gene family with unique binding properties and tissue-specific expression.
- The distinct expression pattern suggests FGFR-4 plays specific cell lineage and tissue-dependent roles.
- FGFR-4 contributes to the diverse functions of fibroblast growth factor receptors in biological processes.