Fibroblast growth factor-7(FGF-7) is one of 22 known members of the mouse FGF family of secreted proteins that plays a key role in development, morphogenesis, angiogenesis, wound healing, and tumorigenesis [1-4]. KGF expression is restricted to cells of mesenchymal origin. When secreted, it acts as a paracrine growth factor for nearby epithelial cells [1]. KGF speeds wound healing by being dramatically upregulated in response to damage to skin or internal structures that results in high local concentrations of inflammatory mediators such as IL-1 and TNF-alpha [2, 5]. KGF promotes cell mig -ration and invasion, and mediates melanocyte transfer to keratinocytes upon UVB radiation [6, 7]. It has been used ectopically to avoid chemotherapy -induced oral mucositis in patients with hematological malignancies [1]. Deletion of KGF affects kidney development, producing abnormally small ureteric buds and fewer nephrons [8]. It also impedes hair follicle differentiation [9]. The 194 amino acid (aa) KGF precursor contains a 31 aa signal sequence and, like all other FGFs, an ~120 aa beta -trefoil scaffold that includes receptor- and heparin-binding sites. KGF signals only through the IIIb splice form of the tyrosine kinase receptor, FGF R2 (FGF R2-IIIb/KGF R) [10]. Receptor dimerization requires an octameric or larger heparin or heparin sulfate proteoglycan [11]. FGF-10, also called KGF2, shares 51% aa identity and similar function to KGF, but shows more limited expression than KGF and uses an additional receptor, FGF R2-IIIc [12]. Following receptor engagement, KGF is typically degraded, while FGF-10 is recycled [12]. Mature human KGF, which is active across species, shares 98% aa sequence identity with bovine, equine, ovine and canine, 96% with mouse and porcine, and 92% with rat KGF, respectively.
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