title: Pregnenolone sulphate-independent inhibition of TRPM3 channels by progesterone.
abstract: Transient Receptor Potential Melastatin 3 (TRPM3) is a widely expressed calcium-permeable non-selective cation channel that is stimulated by high concentrations of nifedipine or by physiological steroids that include pregnenolone sulphate. Here we sought to identify steroids that inhibit TRPM3. Channel activity was studied using calcium-measurement and patch-clamp techniques. Progesterone (0.01-10μM) suppressed TRPM3 activity evoked by pregnenolone sulphate. Progesterone metabolites and 17β-oestradiol were also inhibitory but the effects were relatively small. Dihydrotestosterone was an inhibitor at concentrations higher than 1μM. Corticosteroids lacked effect. Overlay assays indicated that pregnenolone sulphate, progesterone and dihydrotestosterone bound to TRPM3. In contrast to dihydrotestosterone, progesterone inhibited nifedipine-evoked TRPM3 activity or activity in the absence of an exogenous activator, suggesting a pregnenolone sulphate-independent mechanism of action. Dihydrotestosterone, like a non-steroid look-alike compound, acted as a competitive antagonist at the pregnenolone sulphate binding site. Progesterone inhibited endogenous TRPM3 in vascular smooth muscle cells. Relevance of TRPM3 or the progesterone effect to ovarian cells, which have been suggested to express TRPM3, was not identified. The data further define a chemical framework for competition with pregnenolone sulphate at TRPM3 and expand knowledge of steroid interactions with TRPM3, suggesting direct steroid binding and pregnenolone sulphate-independent inhibition by progesterone.
authors: Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, UK.
authors: Yasser
authors: Y
authors: Majeed
authors: Sarka
authors: S
authors: Tumova
authors: Ben L
authors: BL
authors: Green
authors: Victoria A L
authors: VA
authors: Seymour
authors: Daniel M
authors: DM
authors: Woods
authors: Anil K
authors: AK
authors: Agarwal
authors: Jacqueline
authors: J
authors: Naylor
authors: Shannon
authors: S
authors: Jiang
authors: Helen M
authors: HM
authors: Picton
authors: Karen E
authors: KE
authors: Porter
authors: David J
authors: DJ
authors: O'Regan
authors: Katsuhiko
authors: K
authors: Muraki
authors: Colin W G
authors: CW
authors: Fishwick
authors: David J
authors: DJ
authors: Beech
mesh_terms: D000305:Adrenal Cortex Hormones / Q000494:pharmacology; D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects; D002417:Cattle; D013196:Dihydrotestosterone / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D006107:Granulosa Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D015735:Mifepristone / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009543:Nifedipine / Q000494:pharmacology; D011284:Pregnenolone / Q000737:chemistry / Q000494:pharmacology*; D011374:Progesterone / Q000737:chemistry / Q000494:pharmacology*; D011485:Protein Binding / Q000187:drug effects; D011980:Receptors, Progesterone / Q000378:metabolism; D050053:TRPM Cation Channels / Q000819:agonists / Q000378:metabolism*
chemical_list: D000305:Adrenal Cortex Hormones; D011980:Receptors, Progesterone; D050053:TRPM Cation Channels; C475667:TRPM3 protein, human; C018370:pregnenolone sulfate; D013196:Dihydrotestosterone; D015735:Mifepristone; D011374:Progesterone; D004958:Estradiol; D011284:Pregnenolone; D009543:Nifedipine