title: Estrogens inhibit mycelium-to-yeast transformation in the fungus Paracoccidioides brasiliensis: implications for resistance of females to paracoccidioidomycosis.
abstract: Evidence that disease due to the thermally dimorphic fungus Paracoccidioides brasiliensis occurs post-puberty predominantly in males led us to hypothesize that hormonal factors critically affect its pathogenesis. We show here that estrogens inhibit mycelial- to yeast-form transformation of P. brasiliensis in vitro. Transformation of three isolates was inhibited to 71, 33, and 19% of the control values in the presence of 10(-10), 10(-8), and 10(-6) M 17 beta-estradiol, respectively. The synthetic estrogen diethylstilbestrol was active but less potent than estradiol, whereas testosterone, 17 alpha-estradiol, tamoxifen, and corticosterone were inactive. This function was specifically inhibited, since yeast-to-mycelium transformation, yeast growth, and yeast reproduction by budding were unaffected by 17 beta-estradiol. Of note is the fact that mycelium-to-yeast transformation occurs as the first step in vivo in the establishment of infection. The cytosol of the three isolates studied possesses a steroid-binding protein which has high affinity for 17 beta-estradiol. We believe that this binding protein represents a P. brasiliensis hormone receptor which can also recognize mammalian estrogens. We hypothesize that the ability of estrogen to decrease or delay mycelium-to-yeast transformation at the initial site of infection contributes to or is responsible for the marked resistance of females, and that the binder described is the molecular site of action.
mesh_terms: D003600:Cytosol / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism; D004967:Estrogens / Q000494:pharmacology*; D005658:Fungi / Q000187:drug effects*; D006801:Humans; D010228:Paracoccidioides / Q000033:anatomy & histology / Q000187:drug effects* / Q000254:growth & development; D010229:Paracoccidioidomycosis / Q000382:microbiology*; D011960:Receptors, Estrogen / Q000378:metabolism
chemical_list: D004967:Estrogens; D011960:Receptors, Estrogen; D004958:Estradiol