title: Aldosterone induces elastin production in cardiac fibroblasts through activation of insulin-like growth factor-I receptors in a mineralocorticoid receptor-independent manner.
abstract: Aldosterone is known to regulate electrolyte homeostasis, but it may also contribute to other processes, including the maladaptive remodeling of postinfarct hearts. Because aldosterone has been implicated in the stimulation of collagen production in the heart, we investigated whether it would also affect elastin deposition in cultures of human cardiac fibroblasts. We first demonstrated that treatment with 1 to 50 nmol/L aldosterone leads to a significant increase in collagen type I mRNA levels and in subsequent collagen fiber deposition. Pretreatment of cells with the mineralocorticoid receptor antagonist spironolactone, but not with the glucocorticoid receptor antagonist RU 486, inhibited collagen synthesis in aldosterone-treated cultures. Most importantly, we demonstrated that aldosterone also increases elastin mRNA levels, tropoelastin synthesis, and elastic fiber deposition in a dose-dependent manner. Strikingly, neither spironolactone nor RU 486 eliminated aldosterone-induced increases in elastin production. We further discovered that the proelastogenic effect of aldosterone involves a rapid increase in tyrosine phosphorylation of the insulin-like growth factor-I receptor and that the insulin-like growth factor-I receptor kinase inhibitor AG1024 or an anti-insulin-like growth factor-I receptor-neutralizing antibody inhibits both insulin-like growth factor-I and aldosterone-induced elastogenesis. Thus, we have demonstrated for the first time that aldosterone, which stimulates collagen production through the mineralocorticoid receptor-dependent pathway, also increases elastogenesis via a parallel mineralocorticoid receptor-independent pathway involving I insulin-like growth factor-I receptor signaling.
authors.affiliation: Cardiovascular Research Program, University of Toronto, Ontario, Canada.
authors.forename: Severa
authors.initials: S
authors.lastname: Bunda
authors.forename: Peter
authors.initials: P
authors.lastname: Liu
authors.forename: Yanting
authors.initials: Y
authors.lastname: Wang
authors.forename: Kela
authors.initials: K
authors.lastname: Liu
authors.forename: Aleksander
authors.initials: A
authors.lastname: Hinek
mesh_terms: D000450:Aldosterone / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D004549:Elastin / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation; D006727:Hormone Antagonists / Q000494:pharmacology; D006801:Humans; D015735:Mifepristone / Q000494:pharmacology; D000451:Mineralocorticoid Receptor Antagonists / Q000494:pharmacology; D009206:Myocardium / Q000166:cytology*; D010766:Phosphorylation; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000378:metabolism*; D018161:Receptors, Mineralocorticoid / Q000378:metabolism*; D013148:Spironolactone / Q000494:pharmacology; D014333:Tropoelastin / Q000235:genetics / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
chemical_list: D024042:Collagen Type I; D006727:Hormone Antagonists; D000451:Mineralocorticoid Receptor Antagonists; D018161:Receptors, Mineralocorticoid; D014333:Tropoelastin; D013148:Spironolactone; D015735:Mifepristone; D014443:Tyrosine; D000450:Aldosterone; D004549:Elastin; D017526:Receptor, IGF Type 1