title: Dietary Mg2+ regulates the epithelial Mg2+ channel TRPM6 in rat mammary tissue.
abstract: The epithelial Mg(2+) channel TRPM6 is considered a pivotal component in active Mg(2+)absorption and re-absorption in the intestine and kidney, but its expression and function in other tissues are largely unknown. We have previously demonstrated that extracellular Mg(2+) availability modulates TRPM6, but not the ubiquitous TRPM7, in cultured mammary epithelial cells; in addition, TRPM6 protein expression correlated to Mg(2+) influx capacities. Our results closely remind the modulation of TRPM6 described by others in murine kidney and colon following Mg(2+) dietary restriction. We sought to validate our observations by investigating whether TRPM6 modulation by extracellular Mg(2+)also occurs in vivo. To this aim, we exploited a model consisting of rats fed either with a Mg(2+)-deficient or a Mg(2+)-enriched diet, and studied TRPM6 expression in breast and kidney tissues. Immunohistochemical and western blot analyses confirmed that rat mammary tissues express TRPM6 protein levels similar to those found in the kidney, and that protein expression is modulated by dietary Mg(2+). In particular, Mg(2+) restriction upregulated TRPM6 expression, while Mg(2+) supplementation resulted in a significant decrease in protein levels. This work confirms and extends our previous results on TRPM6 modulation by Mg(2+) availability in mammary tissues. Further studies are required to clarify the functional significance of these findings, and the role of TRPM6 in tissue-specific magnesium homeostasis.
authors.affiliation: Istituto di Patologia Generale e Centro di Ricerche Oncologiche Giovanni XXIII, Facoltà di Medicina e Chirurgia A. Gemelli, Università Cattolica del Sacro Cuore, Rome, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Mastrototaro
authors.forename: Valentina
authors.initials: V
authors.lastname: Trapani
authors.forename: Alma
authors.initials: A
authors.lastname: Boninsegna
authors.forename: Hélène
authors.initials: H
authors.lastname: Martin
authors.forename: Sylvie
authors.initials: S
authors.lastname: Devaux
authors.forename: Alain
authors.initials: A
authors.lastname: Berthelot
authors.forename: Achille
authors.initials: A
authors.lastname: Cittadini
authors.forename: Federica I
authors.initials: FI
authors.lastname: Wolf
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001835:Body Weight / Q000187:drug effects; D019587:Dietary Supplements; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D007150:Immunohistochemistry; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D008274:Magnesium / Q000097:blood / Q000494:pharmacology*; D008321:Mammary Glands, Animal / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D050053:TRPM Cation Channels / Q000378:metabolism*
chemical_list: D050053:TRPM Cation Channels; C507531:TRPM6 protein, rat; D008274:Magnesium