Journal
KIDNEY INTERNATIONAL
Volume 60, Issue 6, Pages 2079-2086Publisher
BLACKWELL SCIENCE INC
DOI: 10.1046/j.1523-1755.2001.00064.x
Keywords
FGF23; 12p13; chromosome 12; hypophosphatemia; site-directed mutagenesis; proprotein convertase; renal phosphate wasting; fibroblast growth factor
Categories
Funding
- NIAMS NIH HHS [AR08550, AR02095, AR42228] Funding Source: Medline
- NIA NIH HHS [AG05793] Funding Source: Medline
- NINDS NIH HHS [NS26630] Funding Source: Medline
Ask authors/readers for more resources
Background. The gene for the renal phosphate wasting disorder autosomal-dominant hypophosphatemic rickets (ADHR) is FGF23, which encodes a secreted protein related to the fibroblast growth factors (FGFs). We previously detected missense mutations R176Q, R179W, and R179Q in FGF23 front ADHR kindreds. The mutations replace R residues within a subtilisin-like proprotein convertase (SPC) cleavage site 176RHTR-179 (RXXR motif). The goal of these studies was to determine if the ADHR mutations lead to protease resistance of FGF-23. Methods. The ADHR mutations were introduced into human FGF-23 cDNA clones with or without an N-terminal FLAG tag by site-directed mutagenesis and were transiently transfected into HEK293 cells. Protein expression was determined by Western analyses. Results. Antibodies directed toward the C-terminal portion of FGF-23 revealed that the native FGF-23 protein resolved as 32 kD and 12 kD species in HEK293 conditioned media; however, the three mutated proteins were detected only as the 32 kD band. An N-terminal FLAG-tagged native FGF-23 resolved as two bands of 36 kD and 26 kD when detected with a FLAG antibody, whereas the R176Q mutant resolved primarily as the 36 kD protein species. Cleavage of FGF-23 was not enhanced by extracellular incubation of FGF-23 with HEK293 cells. Native and mutant FGF-23s bound heparin. Conclusions. FGF-23 proteins containing the ADHR mutations are secreted, and produce polypeptides less sensitive to protease cleavage than wild-type FGF-23. Therefore, the ADHR mutations may protect FGF-23 from proteolysis, thereby potentially elevating circulating concentrations of FGF-23 and leading to phosphate wasting in ADHR patients.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available