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Calamita G, Delporte C. Insights into the Function of Aquaporins in Gastrointestinal Fluid Absorption and Secretion in Health and Disease. Cells 2023; 12:2170. [PMID: 37681902 PMCID: PMC10486417 DOI: 10.3390/cells12172170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 08/16/2023] [Accepted: 08/17/2023] [Indexed: 09/09/2023] Open
Abstract
Aquaporins (AQPs), transmembrane proteins permeable to water, are involved in gastrointestinal secretion. The secretory products of the glands are delivered either to some organ cavities for exocrine glands or to the bloodstream for endocrine glands. The main secretory glands being part of the gastrointestinal system are salivary glands, gastric glands, duodenal Brunner's gland, liver, bile ducts, gallbladder, intestinal goblet cells, exocrine and endocrine pancreas. Due to their expression in gastrointestinal exocrine and endocrine glands, AQPs fulfill important roles in the secretion of various fluids involved in food handling. This review summarizes the contribution of AQPs in physiological and pathophysiological stages related to gastrointestinal secretion.
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Affiliation(s)
- Giuseppe Calamita
- Department of Biosciences, Biotechnologies and Environment, University of Bari Aldo Moro, 70125 Bari, Italy;
| | - Christine Delporte
- Laboratory of Pathophysiological and Nutritional Biochemistry, Faculty of Medicine, Université Libre de Bruxelles, 1070 Brussels, Belgium
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Aquaporins Display a Diversity in their Substrates. J Membr Biol 2023; 256:1-23. [PMID: 35986775 DOI: 10.1007/s00232-022-00257-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 07/13/2022] [Indexed: 02/07/2023]
Abstract
Aquaporins constitute a family of transmembrane proteins that function to transport water and other small solutes across the cell membrane. Aquaporins family members are found in diverse life forms. Aquaporins share the common structural fold consisting of six transmembrane alpha helices with a central water-transporting channel. Four such monomers assemble together to form tetramers as their biological unit. Initially, aquaporins were discovered as water-transporting channels, but several studies supported their involvement in mediating the facilitated diffusion of different solutes. The so-called water channel is able to transport a variety of substrates ranging from a neutral molecule to a charged molecule or a small molecule to a bulky molecule or even a gas molecule. This article gives an overview of a diverse range of substrates conducted by aquaporin family members. Prime focus is on human aquaporins where aquaporins show a wide tissue distribution and substrate specificity leading to various physiological functions. This review also highlights the structural mechanisms leading to the transport of water and glycerol. More research is needed to understand how one common fold enables the aquaporins to transport an array of solutes.
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Calamita G, Delporte C. Aquaporins in Glandular Secretion. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1398:225-249. [PMID: 36717498 DOI: 10.1007/978-981-19-7415-1_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Exocrine and endocrine glands deliver their secretory product, respectively, at the surface of the target organs or within the bloodstream. The release of their products has been shown to rely on secretory mechanisms often involving aquaporins (AQPs). This chapter will provide insight into the role of AQPs in secretory glands located within the gastrointestinal tract, including salivary glands, gastric glands, duodenal Brunner's glands, liver, gallbladder, intestinal goblets cells, and pancreas, as well and in other parts of the body, including airway submucosal glands, lacrimal glands, mammary glands, and eccrine sweat glands. The involvement of AQPs in both physiological and pathophysiological conditions will also be highlighted.
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Affiliation(s)
- Giuseppe Calamita
- Department of Biosciences, Biotechnologies and Environment, University of Bari "Aldo Moro", Bari, Italy
| | - Christine Delporte
- Laboratory of Pathophysiological and Nutritional Biochemistry, Faculty of Medicine, Université Libre de Bruxelles, Brussels, Belgium.
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D’Agostino C, Elkashty OA, Chivasso C, Perret J, Tran SD, Delporte C. Insight into Salivary Gland Aquaporins. Cells 2020; 9:cells9061547. [PMID: 32630469 PMCID: PMC7349754 DOI: 10.3390/cells9061547] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 06/23/2020] [Accepted: 06/23/2020] [Indexed: 12/18/2022] Open
Abstract
The main role of salivary glands (SG) is the production and secretion of saliva, in which aquaporins (AQPs) play a key role by ensuring water flow. The AQPs are transmembrane channel proteins permeable to water to allow water transport across cell membranes according to osmotic gradient. This review gives an insight into SG AQPs. Indeed, it gives a summary of the expression and localization of AQPs in adult human, rat and mouse SG, as well as of their physiological role in SG function. Furthermore, the review provides a comprehensive view of the involvement of AQPs in pathological conditions affecting SG, including Sjögren's syndrome, diabetes, agedness, head and neck cancer radiotherapy and SG cancer. These conditions are characterized by salivary hypofunction resulting in xerostomia. A specific focus is given on current and future therapeutic strategies aiming at AQPs to treat xerostomia. A deeper understanding of the AQPs involvement in molecular mechanisms of saliva secretion and diseases offered new avenues for therapeutic approaches, including drugs, gene therapy and tissue engineering. As such, AQP5 represents a potential therapeutic target in different strategies for the treatment of xerostomia.
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Affiliation(s)
- Claudia D’Agostino
- Laboratory of Pathophysiological and Nutritional Biochemistry, Faculty of Medicine, Université Libre de Bruxelles, 808 Route de Lennik, Blg G/E CP 611, B-1070 Brussels, Belgium; (C.D.); (C.C.); (J.P.)
| | - Osama A. Elkashty
- McGill Craniofacial Tissue Engineering and Stem Cells Laboratory, Faculty of Dentistry, McGill University, Montreal, QC H3A 0C7, Canada; (O.A.E.); (S.D.T.)
- Oral Pathology Department, Faculty of Dentistry, Mansoura University, 35516 Mansoura, Egypt
| | - Clara Chivasso
- Laboratory of Pathophysiological and Nutritional Biochemistry, Faculty of Medicine, Université Libre de Bruxelles, 808 Route de Lennik, Blg G/E CP 611, B-1070 Brussels, Belgium; (C.D.); (C.C.); (J.P.)
| | - Jason Perret
- Laboratory of Pathophysiological and Nutritional Biochemistry, Faculty of Medicine, Université Libre de Bruxelles, 808 Route de Lennik, Blg G/E CP 611, B-1070 Brussels, Belgium; (C.D.); (C.C.); (J.P.)
| | - Simon D. Tran
- McGill Craniofacial Tissue Engineering and Stem Cells Laboratory, Faculty of Dentistry, McGill University, Montreal, QC H3A 0C7, Canada; (O.A.E.); (S.D.T.)
| | - Christine Delporte
- Laboratory of Pathophysiological and Nutritional Biochemistry, Faculty of Medicine, Université Libre de Bruxelles, 808 Route de Lennik, Blg G/E CP 611, B-1070 Brussels, Belgium; (C.D.); (C.C.); (J.P.)
- Correspondence: ; Tel.: +32-2-5556210
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Abstract
Aquaporins (AQPs ) are expressed in most exocrine and endocrine secretory glands. Consequently, summarizing the expression and functions of AQPs in secretory glands represents a daunting task considering the important number of glands present in the body, as well as the number of mammalian AQPs - thirteen. The roles played by AQPs in secretory processes have been investigated in many secretory glands. However, despite considerable research, additional studies are clearly needed to pursue our understanding of the role played by AQPs in secretory processes. This book chapter will focus on summarizing the current knowledge on AQPs expression and function in the gastrointestinal tract , including salivary glands, gastric glands, Duodenal Brunner's gland, liver and gallbladder, intestinal goblets cells, exocrine and endocrine pancreas, as well as few other secretory glands including airway submucosal glands, lacrimal glands, mammary glands and eccrine sweat glands.
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Affiliation(s)
- Christine Delporte
- Laboratory of Pathophysiological and Nutritional Biochemistry, Faculty of Medicine, Université Libre de Bruxelles, Brussels, Belgium.
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Aquaporins in Salivary Glands: From Basic Research to Clinical Applications. Int J Mol Sci 2016; 17:ijms17020166. [PMID: 26828482 PMCID: PMC4783900 DOI: 10.3390/ijms17020166] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 01/20/2016] [Accepted: 01/21/2016] [Indexed: 01/06/2023] Open
Abstract
Salivary glands are involved in saliva secretion that ensures proper oral health. Aquaporins are expressed in salivary glands and play a major role in saliva secretion. This review will provide an overview of the salivary gland morphology and physiology of saliva secretion, and focus on the expression, subcellular localization and role of aquaporins under physiological and pathophysiological conditions, as well as clinical applications involving aquaporins. This review is highlighting expression and localization of aquaporins in human, rat and mouse, the most studied species and is pointing out possible difference between major salivary glands, i.e., parotid, submandibular and sublingual glands.
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Are Aquaporins the Missing Transmembrane Osmosensors? J Membr Biol 2015; 248:753-65. [PMID: 25791748 DOI: 10.1007/s00232-015-9790-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 03/12/2015] [Indexed: 01/08/2023]
Abstract
Regulation of cell volume is central to homeostasis. It is assumed to begin with the detection of a change in water potential across the bounding membrane, but it is not clear how this is accomplished. While examples of general osmoreceptors (which sense osmotic pressure in one phase) and stretch-activated ion channels (which require swelling of a cell or organelle) are known, effective volume regulation requires true transmembrane osmosensors (TMOs) which directly detect a water potential difference spanning a membrane. At present, no TMO molecule has been unambiguously identified, and clear evidence for mammalian TMOs is notably lacking. In this paper, we set out a theory of TMOs which requires a water channel spanning the membrane that excludes the major osmotic solutes, responds directly without the need for any other process such as swelling, and signals to other molecules associated with the magnitude of changing osmotic differences. The most likely molecules that are fit for this purpose and which are also ubiquitous in eukaryotic cells are aquaporins (AQPs). We review experimental evidence from several systems which indicates that AQPs are essential elements in regulation and may be functioning as TMOs; i.e. the first step in an osmosensing sequence that signals osmotic imbalance in a cell or organelle. We extend this concept to several systems of current interest in which the cellular involvement of AQPs as simple water channels is puzzling or counter-intuitive. We suggest that, apart from regulatory volume changes in cells, AQPs may also be acting as TMOs in red cells, secretory granules and microorganisms.
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Aquaporins in salivary glands and pancreas. Biochim Biophys Acta Gen Subj 2014; 1840:1524-32. [DOI: 10.1016/j.bbagen.2013.08.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 08/07/2013] [Accepted: 08/08/2013] [Indexed: 12/23/2022]
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Ishibashi K, Tanaka Y, Morishita Y. The role of mammalian superaquaporins inside the cell. Biochim Biophys Acta Gen Subj 2013; 1840:1507-12. [PMID: 24189537 DOI: 10.1016/j.bbagen.2013.10.039] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 10/18/2013] [Accepted: 10/23/2013] [Indexed: 01/06/2023]
Abstract
BACKGROUND The mammalian two superaquaporins, AQP11 and AQP12, are present inside the cell and their null phenotypes in mice suggest their unusual functions. SCOPE OF REVIEW The surveyed literature on these superaquaporins and our unpublished data has been incorporated to speculate their roles. MAJOR CONCLUSIONS AQP11 and AQP12 have unique NPA boxes with a signature cysteine residue. Although some water permeability of AQP11 was demonstrated in liposomes and cultured cells, its permeability to glycerol is unknown. The function of AQP12 still remains to be clarified. AQP11 null mice develop polycystic kidneys following large intracellular vacuoles in the proximal tubule, which may be caused by ER stress or vesicle fusion failure. The role of AQP11 in the kidney and liver seems to alleviate the tissue damage and facilitate the recovery. Its expression in the sperm, thymus and brain suggests its potential roles in these organs in spite of the apparently normal null phenotype. Although AQP12 null mice appear normal, they suffer from severe pancreatitis, suggesting its role in the fusion of zymogen granules. GENERAL SIGNIFICANCE As many issues are unsolved, the clarification of the function and roles of the superaquaporin may lead to the identification of new roles of AQPs. This article is part of a Special Issue entitled Aquaporins.
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Affiliation(s)
- Kenichi Ishibashi
- Department of Medical Physiology, School of Pharmacy, Meiji Pharmaceutical University, Tokyo, Japan.
| | - Yasuko Tanaka
- Department of Medical Physiology, School of Pharmacy, Meiji Pharmaceutical University, Tokyo, Japan
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