Keratinocyte growth factor expression by the bovine corpus luteum

Communication between cells of the corpus luteum (CL) is thought to be necessary for normal luteal function. Keratinocyte growth factor (KGF) is produced by mesenchymally derived cells in numerous tissues and acts on epithelial cells. In bovine follicles, theca cells produce KGF, which can stimulate granulosa cell proliferation. Whether KGF is produced by ovarian cells after luteinization is unknown. Our objective was to determine whether KGF mRNA and protein were present in bovine luteal tissue, and if so, to determine what type(s) of luteal cells contains KGF. CL (n = 3-4/day) were obtained from specific days throughout diestrus. Presence of KGF mRNA in CL was determined using a porcine KGF anti-sense cRNA probe. Northern analyses of luteal tissue poly(A)+ RNA revealed a single transcript (approximately 2.0 kilobases), the quantity of which did not change throughout diestrus. Western analysis revealed an immunoreactive band (28 kDa) in luteal tissues and theca cell homogenates that was absent from granulosa cell homogenates. Immunocytochemistry showed KGF predominantly in theca and small luteal cells. Results indicate that bovine CL produce and contain KGF, which is primarily localized in small luteal cells. Therefore, KGF may participate in paracrine communication within the bovine CL.