Specific receptor detection by a functional keratinocyte growth factor-immunoglobulin chimera.
Fibroblast growth factor receptors (FGFRs) are encoded by at least four distinct highly conserved genes, and alternative splicing generates multiple gene products. The close relationship among different FGFRs has greatly increased the difficulty in generating specific immunochemical probes. As an alternative strategy, we constructed a fusion protein comprising keratinocyte growth factor (KGF) and an IgG1 Fc domain (HFc). The chimeric molecule was efficiently secreted from transfectants as a disulfide-linked dimer that bound KGFRs with high affinity. Moreover, the KGF-HFc, like native KGF, induced DNA synthesis by epithelial cells implying normal functional receptor activation. Because it retained the convenient detection properties of an immunoglobulin, it was possible to use the KGF-HFc in ligand-mediated histochemical analysis of KGFRs. Flow cytometry revealed KGF-HFc chimera detection of the KGFR, an alternative FGFR2 product, but not FGFR1 (flg) or FGFR2 (bek). Histochemical analysis of normal skin demonstrated the specific localization of KGFRs within the spinous layer, a zone of epithelial cell differentiation. KGFRs were also localized to epithelial cells within a specific region of the hair follicle, and they were not detectable in cells of the sweat gland. Tissue sections of soft palate and tonsil, two examples of nonkeratinizing epithelium, revealed staining of stratum spinosum and some staining of the basal cell layer as well. Neither salivary gland epithelium nor lymphoid cells were positive. The ciliated epithelium of the trachea exhibited KGFR expression in intermediate and basal cell layers. In striking contrast to the normal pattern of staining in the adjacent epithelium, a squamous cell carcinoma of skin lacked detectable KGFRs. Our present findings suggest that growth factor-Ig fusion proteins may be generally applicable in ligand-mediated histochemical detection and localization of growth factor receptors.
LaRochelle
W J
WJ
National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Dirsch
O R
OR
Finch
P W
PW
Cheon
H G
HG
May
M
M
Marchese
C
C
Pierce
J H
JH
Aaronson
S A
SA
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000096:biosynthesis; D004847:Epithelial Cells; D004848:Epithelium / Q000737:chemistry / Q000378:metabolism; D051526:Fibroblast Growth Factor 10; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors; D000091344:Filaggrin Proteins; D006133:Growth Substances / Q000235:genetics / Q000502:physiology; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000235:genetics; D007150:Immunohistochemistry; D051379:Mice; D015335:Molecular Probes; D008969:Molecular Sequence Data; D009928:Organ Specificity; D011487:Protein Conformation; D012333:RNA, Messenger / Q000032:analysis; D051497:Receptor, Fibroblast Growth Factor, Type 2; D017468:Receptors, Fibroblast Growth Factor; D017978:Receptors, Growth Factor / Q000032:analysis*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000502:physiology; D012680:Sensitivity and Specificity; D012867:Skin / Q000737:chemistry; D014407:Tumor Cells, Cultured
C496453:FGF7 protein, human; C000717249:FLG protein, human; C496454:Fgf7 protein, mouse; D051526:Fibroblast Growth Factor 10; D000091344:Filaggrin Proteins; D006133:Growth Substances; D007141:Immunoglobulin Fc Fragments; D015335:Molecular Probes; D012333:RNA, Messenger; D017468:Receptors, Fibroblast Growth Factor; D017978:Receptors, Growth Factor; D011993:Recombinant Fusion Proteins; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors; D004247:DNA; D051497:Receptor, Fibroblast Growth Factor, Type 2; C065104:keratinocyte growth factor receptor