Abstract
We have previously cloned and sequenced a newt keratinocyte growth factor receptor (KGFR) cDNA which exhibited a unique spatial and temporal expression pattern in the regenerating newt limb. In this report, we further characterize the biochemical and functional properties of this newt KGFR. A stable Chinese hamster ovary transfectant overexpressing the newt KGFR was capable of binding both 125I-fibroblast growth factor-1 (FGF-1) and 125I-FGF-7 but not 125I-FGF-2, indistinguishable from the human KGFR. Scatchard analysis and cross-linking studies further support the conclusion that FGF-1 and FGF-7 are the ligands for the newt KGFR. In addition to their ability to bind to FGFs, both the human and the newt KGFR are also capable of repressing differentiation in mouse MM14 myoblasts. MM14 cells express FGFR1 and are repressed from differentiation by FGF-1, FGF-2, and FGF-4 but not FGF-7. Co-transfection of MM14 cells with either a human or newt KGFR expression construct conferred a response to FGF-7 as determined by a human alpha-cardiac actin/luciferase reporter construct. The response to FGF-7 was similar to the endogenous FGF response as FGF-7 prevented MM14 myoblasts from undergoing terminal differentiation. Thus, both the human and the newt KGFRs transduce signals similar to those transduced via the endogenous mouse FGFR1. Together these data indicate that this newly isolated newt KGFR is a functional receptor as it binds two FGF family members with high affinity and mediates signaling in skeletal muscle myoblasts. Because the binding pattern of the newt KGFR is similar to the pattern observed for its mammalian counterpart, it emphasizes the strict conservation that this ligand/receptor system has undergone through evolution.
Highlights
We have previously cloned and sequenced a newt keratinocyte growth factor receptor (KGFR) cDNA which exhibited a unique spatial and temporal expression pattern in the regenerating newt limb
We further showed that KGFR is the FGFR2 variant that is expressed in the basal layer of the wound epithelium [40]
Newt KGFR cDNA Construction—We have previously reported the isolation from the newt, Notophthalamus viridescens, of overlapping cDNAs which encode the amphibian homologs of two FGFR2 splice variants, bek and KGFR [22]
Summary
We have previously cloned and sequenced a newt keratinocyte growth factor receptor (KGFR) cDNA which exhibited a unique spatial and temporal expression pattern in the regenerating newt limb. Both the human and the newt KGFRs transduce signals similar to those transduced via the endogenous mouse FGFR1 Together these data indicate that this newly isolated newt KGFR is a functional receptor as it binds two FGF family members with high affinity and mediates signaling in skeletal muscle myoblasts. The COOH-terminal half of this domain in FGFR1 is encoded by three alternative exons (IIIa, IIIb, and IIIc) that can result in the expression of a secreted receptor and two different transmembrane receptors, respectively. Exons IIIb and IIIc have homologs in the FGFR2 gene [19] Their mutually exclusive splicing in the second half of Ig domain III results in the bek (IIIc) isoform [4, 6, 21] or the KGF receptor (KGFR) (IIIb) isoform [15, 17, 18, 22]. The expression of this receptor in mouse MM14 myoblast cells represses terminal differentiation mediated by FGF-7
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
