title: Aquaporins Mediate Silicon Transport in Humans.
abstract: In animals, silicon is an abundant and differentially distributed trace element that is believed to play important biological functions. One would thus expect silicon concentrations in body fluids to be regulated by silicon transporters at the surface of many cell types. Curiously, however, and even though they exist in plants and algae, no such transporters have been identified to date in vertebrates. Here, we show for the first time that the human aquaglyceroporins, i.e., AQP3, AQP7, AQP9 and AQP10 can act as silicon transporters in both Xenopus laevis oocytes and HEK-293 cells. In particular, heterologously expressed AQP7, AQP9 and AQP10 are all able to induce robust, saturable, phloretin-sensitive silicon transport activity in the range that was observed for low silicon rice 1 (lsi1), a silicon transporter in plant. Furthermore, we show that the aquaglyceroporins appear as relevant silicon permeation pathways in both mice and humans based on 1) the kinetics of substrate transport, 2) their presence in tissues where silicon is presumed to play key roles and 3) their transcriptional responses to changes in dietary silicon. Taken together, our data provide new evidence that silicon is a potentially important biological element in animals and that its body distribution is regulated. They should open up original areas of investigations aimed at deciphering the true physiological role of silicon in vertebrates.
authors: L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada.
authors: Alexandre P
authors: AP
authors: Garneau
authors: L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada.
authors: Gabriel A
authors: GA
authors: Carpentier
authors: L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada.
authors: Andrée-Anne
authors: AA
authors: Marcoux
authors: L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada.
authors: Rachelle
authors: R
authors: Frenette-Cotton
authors: L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada.
authors: Charles F
authors: CF
authors: Simard
authors: Department of Phytology, Faculty of Sciences of Agriculture and Alimentation, Laval Université Laval, Québec City, Québec, Canada.
authors: Wilfried
authors: W
authors: Rémus-Borel
authors: L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada.
authors: Luc
authors: L
authors: Caron
authors: L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada.
authors: Mariève
authors: M
authors: Jacob-Wagner
authors: L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada.
authors: Micheline
authors: M
authors: Noël
authors: Medical Research Council Human Nutrition Research, Elsie Widdowson Laboratory, Cambridge, United Kingdom.
authors: Jonathan J
authors: JJ
authors: Powell
authors: Department of Phytology, Faculty of Sciences of Agriculture and Alimentation, Laval Université Laval, Québec City, Québec, Canada.
authors: Richard
authors: R
authors: Bélanger
authors: L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada.
authors: François
authors: F
authors: Côté
authors: L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada.
authors: Paul
authors: P
authors: Isenring
mesh_terms: D000818:Animals; D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D001693:Biological Transport, Active / Q000187:drug effects / Q000235:genetics; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D010693:Phloretin / Q000494:pharmacology; D012825:Silicon / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D020346:Aquaporins; D010693:Phloretin; D012825:Silicon