DETECTION OF KERATINOCYTE GROWTH-FACTOR (KGF) MESSENGER-RIBONUCLEIC-ACID AND IMMUNOLOCALIZATION OF KGF IN THE CANINE TESTIS

Keratinocyte growth factor (KGF) was originally discovered in human em bryonic lung fibroblasts and is a member of the fibroblast growth fact or (FGF) family. Members of the FGF family have been shown to regulate testicular function. However, the recently discovered KGF has not bee n studied in the testis. KGF has been detected in many other tissues, including the prostate, an organ whose development and function have b een associated with presence of the testis. In this study, KGF mRNA wa s detected in the whole testis using reverse transcription polymerase chain reaction (RT-PCR). The 575-bp KGF-specific product was detected along with a 594-bp beta-actin-specific product. To identify the cell types in which KGF mRNA was predominantly expressed, interstitial cell s were physically separated from seminiferous tubules. The interstitia l cells were then sorted on a discontinuous Percoll gradient and total cellular mRNAs isolated. Using RT-PCR and Southern hybridization with specific cDNA probes, the KGF mRNA was detected in interstitial cells . KGF expression levels were then evaluated semiquantitatively with a competitive RT-PCR assay. KGF expression levels were highest in inters titial cells that equilibrated between 20 and 30% Percoll. Enriched Le ydig cells and seminiferous tubules expressed low levels of KGF. Final ly, immunohistochemical analysis was performed on canine testes using a rabbit anti-KGF polyclonal antibody. The KGF protein was localized p redominantly to peritubular cells of the canine testis. These results suggest that KGF is synthesized in the canine testis.