ROLE OF AQUAPORINS IN THE IMPROVEMENT OF ADIPOSITY AND NON-ALCOHOLIC FATTY LIVER DISEASE AFTER BARIATRIC SURGERY Leire Méndez Giménez de los Galanes SCHOOL OF SCIENCES ROLE OF AQUAPORINS IN THE IMPROVEMENT OF ADIPOSITY AND NON-ALCOHOLIC FATTY LIVER DISEASE AFTER BARIATRIC SURGERY Submitted by Leire Méndez Giménez de los Galanes in partial fulfillment of the requirements for the Doctoral Degree in Biology of the University of Navarra This dissertation has been written under our supervision at the Metabolic Research Laboratory of the University of Navarra and we approved its submission to the Defense Committee. Signed on May, 2017 Prof. Gema Frühbeck Martínez Dr. Amaia Rodríguez Murueta-Goyena ACKNOWLEDGEMENTS I would like to thank the University of Navarra and the CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN) of the Instituto de Salud Carlos III for the financial support of this thesis (PI12/00515) and their grants for the International PhD programme. In addition, this work has been financially supported by Fondo de Investigación Sanitaria-FEDER (PI10/01677, PI13/01430 and PI16/01217) of the Instituto de Salud Carlos III, the Department of Health of the Gobierno de Navarra (61/2014) and the PIUNA project of the University of Navarra (PIUNA 2011-2014). First and foremost, I would like to express my warmest gratitude and appreciation to my supervisors. Prof. Gema Frühbeck, who trusted in me for the first time, for her inestimable help in carrying out this work encouraging me to go even further with her constant intellectual support and enthusiasm for science. She is an epitome of the hard work towards perfection in research and effort. I also want to thank Dr. Amaia Rodríguez, for her patience and total availability to help me in the achievement of this thesis. She has provided invaluable guidance through this entire scientific assignment. I thank her for the logistical support and for being a great motivation. Furthermore, I am always going to be grateful for her suggestions, conversations, and wisdom that she provides me on a daily basis. I appreciate all of her time and ideas that made my PhD experience productive and stimulating. Without the support of these two scientific titans, the present thesis would never have seen the light of day. I would further like to thank my current and former-colleagues of the Metabolic Research Laboratory of the Clínica Universidad de Navarra, an awesome team with whom I am proud to work with. I owe you my gratitude for your friendship, support and expertise during my learning process. My deepest recognition to each and every member of the team, I wish you all a fruitful future in this wonderful laboratory. It has been also a pleasure to meet the students of the School of Medicine and international PhD exchanges working in our lab during these years. Thank you for all the nice things that we have learned together. We are lucky to have you. I am also grateful to all the staff of the breeding house of the Centro de Investigación Farmacológica Aplicada (CIFA) of the University of Navarra for their invaluable work and help with the experimental animals. - I - I would also like to specially thank the researchers that I met at the Faculty of Pharmacy of the University of Lisbon, a city that became my home during my international PhD exchange. I would like to deeply thank Dr. Graça Soveral for giving me the opportunity to learn new and interesting techniques in her research group as well as for her continuous encouragement and guidance. I would further like to thank her research team for the help, advice and invaluable support during the experiments. Thank you all for your kindness, sympathy and the hospitality, making me to feel part of your group. Thank you, for science and above all, for humanity. In summary, I would like to point out that although only my name appears on the cover of this work, many people have contributed to its elaboration. I owe my gratitude to all those who made this thesis possible and have offered an unforgettable experience to me. Finally, to life and science, for inspiring us to learn more and more. - II - ABBREVIATIONS Adipo-IR: adipose tissue insulin resistance index AQP: aquaporin ATGL: adipose triglyceride lipase BAT: brown adipose tissue BMI: body mass index CD36: fatty acid translocase DBP: diastolic blood pressure DEXA: dual-energy X-ray absorptiometry EWAT: epididymal white adipose tissue EWL: excess weight loss FABP: fatty acid binding protein FATP: fatty acid transporter protein FFA: free fatty acids FGF: fibroblast growth factor FXR: farnesoid X receptor G6Pase: glucose-6-phosphatase GH: growth hormone GHS-R: growth hormone secretagogue receptor GIP: gastric inhibitory peptide GK: glycerol kinase GLP-1: glucagon-like peptide-1 GOAT: ghrelin O-acyltransferase HFD: high-fat diet HOMA: homeostasis model assessment HSL: hormone-sensitive lipase - III - IL: interleukin IPITT: intraperitoneal insulin tolerance test IRE: insulin response element IRS: insulin receptor substrate HFD: high-fat diet LPL: lipoprotein lipase mTOR: mechanistic target of rapamycin NAFLD: non-alcoholic fatty liver disease NASH: non-alcoholic steatohepatitis ND: normal diet NO: nitric oxide NPA: asparagine-proline-alanine motif OGTT: oral glucose tolerance test PEPCK: phosphoenolpyruvate carboxykinase Pf: water permeability Pgly: glycerol permeability PI3K: phosphatidylinositol 3-kinase PKA: protein kinase A PP: pancreatic polypeptide PPAR: peroxisome proliferator-activated receptor PPRE: peroxisome proliferator-activated receptor response element PRWAT: perirenal white adipose tissue PYY: peptide YY RYGB: Roux-en-Y gastric bypass SBP: systolic blood pressure SCWAT: subcutaneous white adipose tissue - IV - SREBF1: sterol regulatory element-binding transcription factor 1 SVFC: stroma-vascular fraction cells TGR5: G-protein-coupled receptor bile acid receptor 5 T2D: type 2 diabetes TG: triacylglycerols TNF- : tumor necrosis factor UCP1: uncoupling protein 1 VLDL: very-low density lipoprotein VRAC: volume-regulated anion channel WAT: white adipose tissue WHO: World Health Organization - V -