Abstract
Growth factors synthesized by ovarian somatic cells directly affect oocyte growth and function, but it is unclear whether oocyte-secreted factors play a reciprocal role in modulating somatic cell functions in vivo. Granulin (grn) and its precursor are polypeptides that possess growth-regulatory activities principally toward epithelial cells. To determine the localization of grn in rat ovary, we produced rabbit polyclonal antibodies that identified grn precursor protein using synthetic peptides. Four kinds of peptide on the basis of rat grn precursor protein were synthesized and immunized with a total of eight rabbits. All eight antisera were found to bind the original synthetic peptides in solid phase by ELISA method using synthetic peptide. Based on Western analysis of ovarian extracts using one antiserum raised against the synthetic peptides, an immunoreactive band at 67 kDa was detected. Immunohistochemical analysis in both neonatal and adult ovaries indicated that grn-like signals were obtained exclusively in oocytes and not granulosa or theca cells, suggesting the involvement of grn in regulating follicular functions.
