Keratinocyte growth factor expression in human gingival fibroblasts and stimulation of in vitro gene expression by retinoic acid.
BACKGROUND
Keratinocyte growth factor (KGF) is a stromally derived growth factor of the fibroblast growth factor (FGF) family with paracrine effects targeted to influence the growth and differentiation of epithelia. Regional and temporal changes in KGF expression play important roles in the development and maintenance of epithelial structures and in epithelial wound healing. Differing patterns of expression of KGF by fibroblasts in the gingival region could therefore be related to the observed regional variation in the differentiation and behavior of gingival epithelia.


METHODS
The in vitro and in vivo patterns of expression of KGF mRNA in human gingival and periodontal fibroblasts were examined using reverse transcription polymerase chain reactions (RT-PCR) and in situ hybridization with digoxigenin-labeled riboprobes. The patterns observed for human gingiva were compared with those for human skin and for murine tissues.


RESULTS
Gingival and periodontal fibroblasts showed expression of KGF transcripts in vitro, and the degree of expression was markedly influenced by the presence of retinoic acid, an agent known to influence patterns of epithelial differentiation. Sections of human and murine gingiva and skin showed regionally variable expression of transcripts with the cells expressing KGF in the subepithelial, rather than the deeper, connective tissues and periodontium.


CONCLUSIONS
The results point to a role of KGF in the maintenance of normal growth and differentiation of gingival epithelia. A lack of KGF expression by periodontal fibroblasts in vivo is expected to hinder apical epithelial migration and thus stabilize the epithelial attachment. The effects of retinoic acid (RA) on KGF expression in vitro provide an indirect mechanism by which RA may regulate the growth and differentiation of gingival epithelia.
Mackenzie
I C
IC
Department of Adult Dental Health, University of Wales College of Medicine, Heath Park, Cardiff, UK. MackenzielC@cardiff.ac.uk
Gao
Z
Z
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D046508:Culture Techniques; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors / Q000187:drug effects* / Q000235:genetics; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D005881:Gingiva / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D017403:In Situ Hybridization; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism*; D007641:Keratolytic Agents / Q000494:pharmacology*; D051379:Mice; D019899:Paracrine Communication; D010513:Periodontal Ligament / Q000166:cytology / Q000378:metabolism; D015347:RNA Probes; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012867:Skin / Q000166:cytology / Q000378:metabolism; D014158:Transcription, Genetic; D014212:Tretinoin / Q000494:pharmacology*; D014945:Wound Healing
C496453:FGF7 protein, human; C496454:Fgf7 protein, mouse; D007641:Keratolytic Agents; D015347:RNA Probes; D012333:RNA, Messenger; D051523:Fibroblast Growth Factor 7; D014212:Tretinoin; D005346:Fibroblast Growth Factors