title: Biophysical assessment of human aquaporin-7 as a water and glycerol channel in 3T3-L1 adipocytes.
abstract: The plasma membrane aquaporin-7 (AQP7) has been shown to be expressed in adipose tissue and its role in glycerol release/uptake in adipocytes has been postulated and correlated with obesity onset. However, some studies have contradicted this view. Based on this situation, we have re-assessed the precise localization of AQP7 in adipose tissue and analyzed its function as a water and/or glycerol channel in adipose cells. Fractionation of mice adipose tissue revealed that AQP7 is located in both adipose and stromal vascular fractions. Moreover, AQP7 was the only aquaglyceroporin expressed in adipose tissue and in 3T3-L1 adipocytes. By overexpressing the human AQP7 in 3T3-L1 adipocytes it was possible to ascertain its role as a water and glycerol channel in a gain-of-function scenario. AQP7 expression had no effect in equilibrium cell volume but AQP7 loss of function correlated with higher triglyceride content. Furthermore it is also reported for the first time a negative correlation between water permeability and the cell non-osmotic volume supporting the observation that AQP7 depleted cells are more prone to lipid accumulation. Additionally, the strong positive correlation between the rates of water and glycerol transport highlights the role of AQP7 as both a water and a glycerol channel and reflects its expression levels in cells. In all, our results clearly document a direct involvement of AQP7 in water and glycerol transport, as well as in triglyceride content in adipocytes.
authors.affiliation: Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL), Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal ; Departmento de Bioquímica e Biologia Humana, Faculdade de Farmácia, Universidade de Lisboa, Lisboa, Portugal.
authors.forename: Ana
authors.initials: A
authors.lastname: Madeira
authors.affiliation: Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain ; Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Camps
authors.affiliation: Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain ; Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain ; CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Zorzano
authors.affiliation: Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL), Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal ; REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal.
authors.forename: Teresa F
authors.initials: TF
authors.lastname: Moura
authors.affiliation: Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL), Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal ; Departmento de Bioquímica e Biologia Humana, Faculdade de Farmácia, Universidade de Lisboa, Lisboa, Portugal ; REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal.
authors.forename: Graça
authors.initials: G
authors.lastname: Soveral
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D051397:Aquaglyceroporins / Q000235:genetics; D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D055592:Biophysical Phenomena; D048429:Cell Size; D005990:Glycerol / Q000378:metabolism*; D006801:Humans; D051379:Mice; D010539:Permeability; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D014280:Triglycerides / Q000378:metabolism; D014867:Water / Q000378:metabolism*
chemical_list: D051397:Aquaglyceroporins; D020346:Aquaporins; D020033:Protein Isoforms; D014280:Triglycerides; D014867:Water; D005990:Glycerol