Tissue-specific protein kinase C isoform expression in rat uterine tissue

OBJECTIVE: Activation of the phosphatidylinositol signaling pathway plays a key role during the generation of agonist-stimulated phasic myometrial con tractions. Protein kinase C (PKC), a component of this signaling pathway, h as been previously shown to produce feedback inhibition of agonist-stimulat ed myometrial contractions. The studies described in this report were perfo rmed to survey the tissue-specific expression of several PKC isoforms in th e rat uterus. METHODS: Uterine tissue was obtained from timed pregnant and normally cycli ng adult female Sprague-Dawley rats. Immunohistochemical studies were perfo rmed using the Vectastain ABC immunostaining technique and PKC isoform-spec ific polyclonal antibodies. Western blot studies were performed using myome trial tissue separated into cytosol and membrane fractions by differential centrifugation. RESULTS: These studies confirmed significant expression of the PKC-alpha, - beta(2), -delta, -eta, and -zeta isoforms in myometrium from pregnant and e strus rats, whereas only trace or no expression of the PKC-beta(1), -gamma, -epsilon. and -theta isoforms was observed. Expression of the PKC-alpha, - beta(2), -delta, -eta, and -zeta isoforms in both circular and longitudinal smooth-muscle layers of the near-term pregnant rat uterus. CONCLUSION: In summary, these studies have confirmed significant levels of expression of several isoforms of PKC in estrus and near-term pregnant rat uterine tissue, which was most prominent in the smooth-muscle cells of the myometrium. (J Soc Gynecol Investig 1999;6:293-300) Copyright (C) 1999 by t he Society for Gynecologic Investigation.