ABSTRACT
CONTENTS Abstract 103 6.1 Introduction 104 6.2 Aquaporins 106
6.2.1AQP0: e Optical Function 106 6.2.2AQP1: e First Aquaporin 107 6.2.3AQP2: Vasopressin-Induced Aquaporin 108 6.2.4AQP4: Brain Function 108 6.2.5AQP5: Saliva, Tears and Pulmonary Secretion 109 6.2.6AQP6: Acid-Base Homeostasis 109 6.2.7AQP8: Digestive Fluid Secretion and Reproductive Function 110
6.3 Aquaglyceroporins 111 6.3.1AQP3: Skin Hydration and Cell Proliferation 112 6.3.2AQP7: Fat Metabolism and Insulin Secretion 112 6.3.3AQP9: Liver Gluconeogenesis and Cancer Treatment 114 6.3.4AQP10: Intestinal Water and Glycerol Absorption 115
6.4 Superaquaporins 115 6.4.1AQP11: Intravesicular Homeostasis and Oxidative Stress 116 6.4.2AQP12: Pancreatic Fluid Secretion 116
6.5Concluding Remarks 116 Acknowledgements 117 References 117
has been extensively studied by analyzing the phenotype of transgenic knockout mice lacking these water channels. AQPs participate in many physiological and pathophysiological processes that include renal water absorption, neuro-homeostasis, tumour angiogenesis, fat metabolism, liver gluconeogenesis and reproduction. Until now functional studies of AQPs in humans are scarce and homozygous mutations in the genes encoding these water channels occasionally show divergent phenotypes to those observed in transgenic mice. Loss-offunction mutations in human AQPs cause congenital cataracts (AQP0), nephrogenic diabetes insipidus (AQP2), antibodies against the GIL blood group (AQP3) and impaired increase in circulating glycerol aer exercise (AQP7). AQP single-nucleotide polymorphisms relevant in clinical medicine are beginning to be explored. Better understanding of the exact mechanisms and regulation of AQPs might be useful for designing potential drug targets against dierent metabolic disorders, such as stroke, glaucoma, brain edema, cancer and obesity.
