title: The interaction of estrogen receptor alpha and caveolin-3 regulates connexin43 phosphorylation in metabolic inhibition-treated rat cardiomyocytes.
abstract: Caveolin-3, the major caveolin isoform in cardiomyocytes, plays an important role in the rapid signaling pathways initiated by stimulation of the membrane-associated molecules. To examine the role of caveolin-3 in regulating estrogen receptor alpha in cardiomyocytes, we investigate whether the membrane estrogen receptor alpha associates with caveolin-3 and whether this association is linked to the 17beta-estradiol-mediated signals. In control cardiomyocytes, following discontinuous sucrose gradient centrifugation, caveolin-3 was found predominantly in the lipid raft buoyant fractions, whereas it was distributed to both the buoyant and non-lipid raft heavy fractions following metabolic inhibition treatment. Confocal microscopy showed that estrogen receptor alpha co-localized with caveolin-3 on the plasma membrane of neonatal and adult rat cardiomyocytes. This membrane labeling of estrogen receptor alpha was not seen following treatment with the cholesterol-depleting agent methyl-beta-cyclodextrin (5mM), whereas metabolic inhibition had little effect on the membrane distribution of estrogen receptor alpha. Metabolic inhibition induced tyrosine phosphorylation of caveolin-3 and decreased its association with estrogen receptor alpha, both effects being mediated via a Src activation mechanism, since they were inhibited by the selective tyrosine kinase inhibitor PP2. Metabolic inhibition also induced tyrosine phosphorylation of connexin43 and increased its association with c-Src, both effects being prevented by 17beta-estradiol (200 nM). The effect of 17beta-estradiol on metabolic inhibition-induced tyrosine phosphorylation of connexin43 was inhibited by the specific estrogen receptor antagonist ICI182780. These data identify cardiac caveolin-3 as juxtamembrane scaffolding for estrogen receptor alpha docking at caveolae, which provide a unique compartment for conveying 17beta-estradiol-elicited, rapid signaling to regulate connexin43 phosphorylation during ischemia.
authors.affiliation: Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, 1-1 Jen-Ai Road, Taipei 10051, Taiwan.
authors.forename: Tun-Hui
authors.initials: TH
authors.lastname: Chung
authors.forename: Seu-Mei
authors.initials: SM
authors.lastname: Wang
authors.forename: Jyun-Yan
authors.initials: JY
authors.lastname: Liang
authors.forename: Shih-Hung
authors.initials: SH
authors.lastname: Yang
authors.forename: Jiahn-Chun
authors.initials: JC
authors.lastname: Wu
mesh_terms: D000375:Aging / Q000473:pathology; D000818:Animals; D051244:Caveolin 3 / Q000378:metabolism*; D002499:Centrifugation, Density Gradient; D018031:Connexin 43 / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D017629:Gap Junctions / Q000187:drug effects / Q000378:metabolism; D021962:Membrane Microdomains / Q000187:drug effects / Q000201:enzymology; D018613:Microscopy, Confocal; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D011743:Pyrimidines / Q000494:pharmacology; D051381:Rats; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D047392:beta-Cyclodextrins / Q000494:pharmacology; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: C412373:AG 1879; D051244:Caveolin 3; D018031:Connexin 43; D047628:Estrogen Receptor alpha; D011743:Pyrimidines; D047392:beta-Cyclodextrins; D019000:Phosphotyrosine; D004958:Estradiol; D019061:src-Family Kinases; C031215:betadex