Pregnenolone sulphate-independent inhibition of TRPM3 channels by progesterone.
Bottom Line: Progesterone metabolites and 17β-oestradiol were also inhibitory but the effects were relatively small.Corticosteroids lacked effect.Relevance of TRPM3 or the progesterone effect to ovarian cells, which have been suggested to express TRPM3, was not identified.
Affiliation: Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, UK.Show MeSH
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Mentions: To investigate whether progesterone or other substances might bind to TRPM3 we performed overlay assays in which cell lysates were applied to membranes spotted with progesterone, pregnenolone sulphate, dihydrotestosterone, cortisol, nifedipine or cholesterol (Fig. 8). Cells were transiently transfected with human TRPM3 tagged with YFP, or GFP-only as a control. Proteins adhering to the spots were detected with anti-GFP antibody, which also binds YFP, a mutant of GFP. TRPM3 bound to pregnenolone sulphate, progesterone, nifedipine, dihydrotestosterone and cholesterol, where as there was no binding to cortisol (Fig. 8). The data are consistent with functional assays in which pregnenolone sulphate, progesterone, nifedipine, dihydrotestosterone and cholesterol have effects on TRPM3 activity but cortisol does not. The data suggest that these TRPM3 modulators act through membrane-delimited mechanisms that involve binding directly to TRPM3, or a partner protein/substance that is tightly bound to TRPM3.
Affiliation: Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, UK.