Proteomic knowledge of human aquaporins

Magni, Fulvio; Sarto, Cecilia; Ticozzi, Davide; Soldi, Monica; Bosso, Niccolò; Mocarelli, Paolo; Kienle, Marzia Galli

doi:10.1002/pmic.200600212

Cited by 88 publications

(59 citation statements)

References 134 publications

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“…They share the same basic architecture with a cytosolic N-and C-terminus and a hydrophobic stretch of six transmembrane domains, connected by three extracellular and two intracellular loops. The transmembrane domains form an hourglass structure with the NPA motifs at the center of the molecule (reviewed in Magni et al (2006)). Several observations of AQP monomers forming a homotetrameric organization in the membrane have been made (Engel et al 2000), and this feature is probably similar for all members of the AQP family.…”

Section: Aqp Protein Familymentioning

confidence: 99%

Metabolic impact of the glycerol channels AQP7 and AQP9 in adipose tissue and liver

Lebeck

2014

Journal of Molecular Endocrinology

102

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Obesity and secondary development of type 2 diabetes (T2D) are major health care problems throughout the developed world. Accumulating evidence suggest that glycerol metabolism contributes to the pathophysiology of obesity and T2D. Glycerol is a small molecule that serves as an important intermediate between carbohydrate and lipid metabolism. It is stored primarily in adipose tissue as the backbone of triglyceride (TG) and during states of metabolic stress, such as fasting and diabetes, it is released for metabolism in other tissues. In the liver, glycerol serves as a gluconeogenic precursor and it is used for the esterification of free fatty acid into TGs. Aquaporin 7 (AQP7) in adipose tissue and AQP9 in the liver are transmembrane proteins that belong to the subset of AQPs called aquaglyceroporins. AQP7 facilitates the efflux of glycerol from adipose tissue and AQP7 deficiency has been linked to TG accumulation in adipose tissue and adult onset obesity. On the other hand, AQP9 expressed in liver facilitates the hepatic uptake of glycerol and thereby the availability of glycerol for de novo synthesis of glucose and TG that both are involved in the pathophysiology of diabetes. The aim of this review was to summarize the current knowledge on the role of the two glycerol channels in controlling glycerol metabolism in adipose tissue and liver. Glycerol metabolismThe metabolic switching between feeding and fasting is central to everyday life and involves tight hormonal control with effects on muscle, adipose tissue, and liver that maintains an adequate handling of metabolic precursors to support energy demands. One of the molecules affected by metabolic switching is glycerol, which is a small 3-carbon alcohol that in the fed state is stored as the backbone of triglyceride (TG) mainly in adipose tissue.In the fed state, after ingestion of dietary fats (w90% TG), !30% of TG is fully hydrolyzed into free fatty acids (FFA) and glycerol. Glycerol rapidly enters the enterocytes of the small intestine and thereafter the circulation through the portal vein and is primarily metabolized by the liver (Lin 1977). In adipose tissue, the activity of glycerol kinase (GlyK), that catalyzes the initial phosphorylation of glycerol into glycerol-3-phosphate (G3P), is negligible and therefore glycerol is not normally utilized in adipose tissue. Instead G3P used for the synthesis of TG in the fed state is derived from glycolysis.During states of increased energy demand, such as fasting and exercise, adipocyte lipolysis is increased by activation of adipose TG lipase and hormone-sensitive

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Section: Aqp Protein Familymentioning

confidence: 99%

Metabolic impact of the glycerol channels AQP7 and AQP9 in adipose tissue and liver

Lebeck

2014

Journal of Molecular Endocrinology

102

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“…Since then, 13 members of this membrane protein family have been identified in humans (AQP0-12), which are distributed throughout a wide range of tissues. For example, AQP1 has been shown to be highly expressed in red blood cells, kidney proximal tubule cells and many other tissues (Magni et al, 2006), while AQP11 has been found at low levels in smooth muscle or cells of the immune system (Ishibashi, 2009). A number of studies have also shown that AQPs play a role in various disorders from renal disease to cerebral oedema (Benarroch, 2007, Schrier andCadnapaphornchai, 2003) and even cancer (Yin et al, 2008, Chae et al, 2008.…”

Section: Introductionmentioning

confidence: 99%

An emerging consensus on aquaporin translocation as a regulatory mechanism

Conner

Bill

Conner

2012

Molecular Membrane Biology

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Water can pass through the cell membrane relatively slowly by diffusion. However, in order to maintain water homeostasis, the rapid and specific regulation of cellular water flow is mediated by the aquaporin (AQP) family of membrane protein water channels. Thirteen human AQPs have been identified to date and the majority are highly specific for water while others show selectivity for water, glycerol and other small solutes. The wide range of tissues that are known to express AQPs is reflected by their involvement in many physiological processes and diseases. Receptor mediated translocation, via hormone activation, is an established method of AQP regulation, especially for AQP2. There is now an emerging consensus that the rapid and reversible translocation of other AQPs from intracellular vesicles to the plasma membrane, triggered by a range of stimuli, can confer increased membrane permeability. This review examines new advances that have identified molecular mechanisms of AQP regulation; these include the role of cytoskeletal proteins, kinases, calcium and retention or localisation signals as well as specific triggers of AQP translocation. This article reviews current knowledge of AQP regulation with a focus on rapid and dynamic regulation of sub-cellular AQP translocation in response to a specific trigger.3

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“…1,2 The classically established role of AQPs in mammalian physiology is in transepithelial fluid transport, as occurs in the urinary concentrating mechanism 3 and glandular fluid secretion. 4,5 Several newer and somewhat unexpected roles of AQPs have been identified, such as in the regulation of brain and corneal water balance, neural signal transduction and glycerol metabolism in skin and fat cells.…”

Section: Introductionmentioning

confidence: 99%