An oestrogen membrane receptor participates in estradiol actions for the prevention of amyloid-beta peptide1-40-induced toxicity in septal-derived cholinergic SN56 cells.
Although oestrogen [17 beta-estradiol (E2)]-related neuroprotection has been demonstrated in different models, the involvement of non-classical oestrogen receptors (ERs) remains unexplored. Using the SN56 cholinergic cell line, we present evidence indicating that an ER associated with the plasma membrane participates in oestrogen-dependent inhibition of cell death induced by amyloid-beta peptide (A beta) toxicity. Similarly to E2 alone, a 15-min exposure to estradiol-horseradish peroxidase (E-HRP) significantly reduced A beta-induced cell death. This effect was decreased by the ER antagonist ICI 182,780 as well as by MC-20 antibody directed to a region neighbouring the ligand-binding domain of ER alpha. Using confocal microscopy on unpermeabilized SN56 cells exposed to MC-20 antibody, we identified a protein at the plasma membrane level. Western blot analysis of purified SN56 cell membrane fractions using MC-20 antibody revealed the presence of one band with the same electrophoretic mobility as intracellular ER alpha. Using conjugated forms of the steroid, E-HRP and E2 conjugated to bovine serum albumin-FITC, we demonstrated by confocal microscopy that SN56 cells contain surface binding sites for E2. Binding of both conjugates was blocked by pre-incubation with E2 and decreased by either ICI 182,780 or MC-20 antibody in a concentration-dependent manner. Thus, a membrane-related ER that shares some structural homologies with ER alpha may participate in oestrogen-mediated neuroprotection.
Marin
Raquel
R
Laboratory of Cellular Neurobiology, Department of Physiology, University of La Laguna, School of Medicine, Sta. Cruz de Tenerife, Spain. rmarin@ull.es
Guerra
Borja
B
Morales
Araceli
A
Díaz
Mario
M
Alonso
Rafael
R
D000109:Acetylcholine / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000633:toxicity*; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001667:Binding, Competitive / Q000187:drug effects; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D004965:Estrogen Antagonists / Q000494:pharmacology; D000077267:Fulvestrant; D051379:Mice; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018696:Neuroprotective Agents / Q000494:pharmacology; D010446:Peptide Fragments / Q000633:toxicity*; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000187:drug effects / Q000378:metabolism*; D020665:Septum of Brain / Q000166:cytology
D016229:Amyloid beta-Peptides; D000906:Antibodies; D004965:Estrogen Antagonists; D018696:Neuroprotective Agents; D010446:Peptide Fragments; D011956:Receptors, Cell Surface; D011960:Receptors, Estrogen; C078592:amyloid beta-protein (1-40); D000077267:Fulvestrant; D004958:Estradiol; D000109:Acetylcholine