1
|
Javitt NB. Hepatic Bile Formation: Developing a New Paradigm. Pharmacol Rev 2023; 75:1036-1042. [PMID: 37532432 DOI: 10.1124/pharmrev.122.000799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 03/07/2023] [Accepted: 04/20/2023] [Indexed: 08/04/2023] Open
Abstract
In 1959, Ivar Sperber contrasted bile formation with that of urine and proposed that water flow into the canalicular conduit is in response to an osmotic, not a hydrostatic, gradient. Early attempts to support the hypothesis using a bile acid, sodium taurocholate, and the hormone secretin to stimulate bile flow led to conflicting data and a moratorium on attempts to further develop the initial proposal. However, current data amplify the initial proposal and indicate both paracellular and transcellular water flow into hepatic ductules and the canalicular conduit in response to an osmotic gradient. Also, the need to further modify the initial proposal became apparent with the recognition that bile acid aggregates (micelles), which form in the canalicular conduit, generate lecithin-cholesterol vesicles that contain water unrelated to an osmotic gradient. As part of this development is the recent introduction of the fluorescent localization after photobleaching technique for direct determination of hepatic duct flow and clarification of the role of biomarkers such as mannitol and polyethylene glycol 900. With the new paradigm, these biomarkers may prove useful for quantifying paracellular and transcellular water flow, respectively. SIGNIFICANCE STATEMENT: It is essential to identify and characterize all the sites for water flow during hepatic bile formation to obtain more precision in evaluating the causes and possible therapeutic approaches to cholestatic syndromes. Updating the Sperber proposal provides a new paradigm that addresses the advances in knowledge that have occurred.
Collapse
Affiliation(s)
- Norman B Javitt
- NYU Grossman School of Medicine, Division of Gastroenterology and Hepatology, New York, New York
| |
Collapse
|
2
|
Eftekhari A, Vahed SZ, Kavetskyy T, Rameshrad M, Jafari S, Chodari L, Hosseiniyan SM, Derakhshankhah H, Ahmadian E, Ardalan M. Cell junction proteins: Crossing the glomerular filtration barrier in diabetic nephropathy. Int J Biol Macromol 2020; 148:475-482. [PMID: 31962072 DOI: 10.1016/j.ijbiomac.2020.01.168] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 01/17/2020] [Accepted: 01/17/2020] [Indexed: 12/20/2022]
Abstract
Diabetic nephropathy as a deleterious complication of diabetes mellitus and an important cause of end-stage renal failure is characterized by changes in the molecular and cellular levels. Cell-cell communication via the gap and tight junctions are involved in the pathogenesis of diseases such as diabetes and kidney failure. Studying cell junctions including gap junctions, tight junctions, and anchoring junctions within the nephron can be used as an early sign of diabetic nephropathy. Furthermore, cell junctions may be an upcoming target by pharmacological methods to improve treatments of diabetic nephropathy and pave the way to introduce promising therapeutic strategies based on cell-cell communications effects and its translation into clinical studies for the treatment of diabetic nephropathy.
Collapse
Affiliation(s)
- Aziz Eftekhari
- Pharmacology and Toxicology Department, Maragheh University of Medical Sciences, Maragheh, Iran
| | | | - Taras Kavetskyy
- Drohobych Ivan Franko State Pedagogical University, Drohobych, Ukraine; The John Paul II Catholic University of Lublin, Lublin, Poland
| | - Maryam Rameshrad
- Natural Products and Medicinal Plants Research Center, North Khorasan University of Medical Sciences, Bojnurd, Iran
| | - Samira Jafari
- Pharmaceutical Sciences Research Center, Health Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Leila Chodari
- Physiology Department, Faculty of Medicine, Urmia University of Medical Sciences, Urmia, Iran
| | | | - Hossein Derakhshankhah
- Pharmaceutical Sciences Research Center, Health Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Elham Ahmadian
- Kidney Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; Students Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran.
| | | |
Collapse
|
3
|
Rosenthal R, Günzel D, Piontek J, Krug SM, Ayala‐Torres C, Hempel C, Theune D, Fromm M. Claudin-15 forms a water channel through the tight junction with distinct function compared to claudin-2. Acta Physiol (Oxf) 2020; 228:e13334. [PMID: 31188544 DOI: 10.1111/apha.13334] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 06/06/2019] [Accepted: 06/07/2019] [Indexed: 12/18/2022]
Abstract
AIM Claudin-15 is mainly expressed in the small intestine and indirectly involved in glucose absorption. Similar to claudin-2 and -10b, claudin-15 is known to form a paracellular channel for small cations. Claudin-2, but not claudin-10b, also forms water channels. Here we experimentally tested whether claudin-15 also mediates water transport and if yes, whether water transport is Na+ -coupled, as seen for claudin-2. METHODS MDCK C7 cells were stably transfected with claudin-15. Ion and water permeability were investigated in confluent monolayers of control and claudin-15-expressing cells. Water flux was induced by an osmotic or ionic gradient. RESULTS Expression of claudin-15 in MDCK cells strongly increased cation permeability. The permeability ratios for monovalent cations indicated a passage of partially hydrated ions through the claudin-15 pore. Accordingly, its pore diameter was determined to be larger than that of claudin-2 and claudin-10b. Mannitol-induced water flux was elevated in claudin-15-expressing cells compared to control cells. In contrast to the Na+ -coupled water flux of claudin-2 channels, claudin-15-mediated water flux was inhibited by Na+ flux. Consequently, water flux was increased in Na+ -free solution. Likewise, Na+ flux was decreased after induction of water flux through claudin-15. CONCLUSION Claudin-15, similar to claudin-2, forms a paracellular cation and water channel. In functional contrast to claudin-2, water and Na+ fluxes through claudin-15 inhibit each other. Claudin-15 allows Na+ to retain part of its hydration shell within the pore. This then reduces the simultaneous passage of additional water through the pore.
Collapse
Affiliation(s)
- Rita Rosenthal
- Department of Gastroenterology, Rheumatology and Infectious Diseases, Institute of Clinical Physiology/Nutritional Medicine Charité – Universitätsmedizin Berlin Berlin Germany
| | - Dorothee Günzel
- Department of Gastroenterology, Rheumatology and Infectious Diseases, Institute of Clinical Physiology/Nutritional Medicine Charité – Universitätsmedizin Berlin Berlin Germany
| | - Jörg Piontek
- Department of Gastroenterology, Rheumatology and Infectious Diseases, Institute of Clinical Physiology/Nutritional Medicine Charité – Universitätsmedizin Berlin Berlin Germany
| | - Susanne M. Krug
- Department of Gastroenterology, Rheumatology and Infectious Diseases, Institute of Clinical Physiology/Nutritional Medicine Charité – Universitätsmedizin Berlin Berlin Germany
| | - Carlos Ayala‐Torres
- Department of Gastroenterology, Rheumatology and Infectious Diseases, Institute of Clinical Physiology/Nutritional Medicine Charité – Universitätsmedizin Berlin Berlin Germany
| | - Caroline Hempel
- Department of Gastroenterology, Rheumatology and Infectious Diseases, Institute of Clinical Physiology/Nutritional Medicine Charité – Universitätsmedizin Berlin Berlin Germany
| | - Dian Theune
- Department of Gastroenterology, Rheumatology and Infectious Diseases, Institute of Clinical Physiology/Nutritional Medicine Charité – Universitätsmedizin Berlin Berlin Germany
| | - Michael Fromm
- Department of Gastroenterology, Rheumatology and Infectious Diseases, Institute of Clinical Physiology/Nutritional Medicine Charité – Universitätsmedizin Berlin Berlin Germany
| |
Collapse
|
4
|
Coalson RD. Driven water/ion transport through narrow nanopores: a molecular dynamics perspective. Faraday Discuss 2018; 209:249-257. [PMID: 30067252 DOI: 10.1039/c8fd00073e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Atomistic Molecular Dynamics (MD) simulations provide numerous insights into the process whereby water is driven through a narrow nanopore (diameter on the order of a few water molecules) by application of hydrostatic pressure. If there are ions in the water, e.g., from dissolved salt, these may be swept along with the flowing water. If the surface of the nanopore is charged, electrostatic interaction between the surface charges and the ions as well as with partial charges on the water molecules will influence the details of the water/ion flow through the channel. Water and ion permeability depend on the geometry of the channel and the degree to which it is charged. Interesting collective features of the water molecules such as water wires that form along the pore axis and rings of water molecules that can insert into the pore perpendicular to the channel axis strongly influence the permeation process, thus emphasizing the importance of molecular level interactions in the mechanism of water and ion flow through conduits with dimensions on the molecular scale.
Collapse
Affiliation(s)
- Rob D Coalson
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA.
| |
Collapse
|
5
|
Samanta P, Wang Y, Fuladi S, Zou J, Li Y, Shen L, Weber C, Khalili-Araghi F. Molecular determination of claudin-15 organization and channel selectivity. J Gen Physiol 2018; 150:949-968. [PMID: 29915162 PMCID: PMC6028499 DOI: 10.1085/jgp.201711868] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 03/08/2018] [Accepted: 05/04/2018] [Indexed: 12/28/2022] Open
Abstract
Members of the claudin family form tight junctions between adjacent epithelial and endothelial cells. Samanta et al. build an atomic model of claudin-15 using molecular dynamics simulations and conclude that four claudin-15 molecules each contribute an aspartic acid residue to form a selectivity filter. Tight junctions are macromolecular structures that traverse the space between adjacent cells in epithelia and endothelia. Members of the claudin family are known to determine tight junction permeability in a charge- and size-selective manner. Here, we use molecular dynamics simulations to build and refine an atomic model of claudin-15 channels and study its transport properties. Our simulations indicate that claudin-15 forms well-defined channels for ions and molecules and otherwise “seals” the paracellular space through hydrophobic interactions. Ionic currents, calculated from simulation trajectories of wild-type as well as mutant channels, reflect in vitro measurements. The simulations suggest that the selectivity filter is formed by a cage of four aspartic acid residues (D55), contributed by four claudin-15 molecules, which creates a negative electrostatic potential to favor cation flux over anion flux. Charge reversal or charge ablation mutations of D55 significantly reduce cation permeability in silico and in vitro, whereas mutations of other negatively charged pore amino acid residues have a significantly smaller impact on channel permeability and selectivity. The simulations also indicate that water and small ions can pass through the channel, but larger cations, such as tetramethylammonium, do not traverse the pore. Thus, our model provides an atomic view of claudin channels, their transport function, and a potential three-dimensional organization of its selectivity filter.
Collapse
Affiliation(s)
| | - Yitang Wang
- Department of Pathology, The University of Chicago, Chicago, IL.,Department of Surgery, The University of Chicago, Chicago, IL
| | - Shadi Fuladi
- Department of Physics, University of Illinois, Chicago, IL
| | - Jinjing Zou
- Department of Pathology, The University of Chicago, Chicago, IL
| | - Ye Li
- Department of Pathology, The University of Chicago, Chicago, IL
| | - Le Shen
- Department of Pathology, The University of Chicago, Chicago, IL .,Department of Surgery, The University of Chicago, Chicago, IL
| | | | | |
Collapse
|
6
|
Marshall WS, Breves JP, Doohan EM, Tipsmark CK, Kelly SP, Robertson GN, Schulte PM. claudin-10 isoform expression and cation selectivity change with salinity in salt-secreting epithelia of Fundulusheteroclitus. ACTA ACUST UNITED AC 2018; 221:jeb.168906. [PMID: 29150449 DOI: 10.1242/jeb.168906] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 11/13/2017] [Indexed: 12/11/2022]
Abstract
To provide insight into claudin (Cldn) tight junction (TJ) protein contributions to branchial salt secretion in marine teleost fishes, this study examined cldn-10 TJ protein isoforms of a euryhaline teleost (mummichog; Fundulus heteroclitus) in association with salinity change and measurements of transepithelial cation selectivity. Mummichogs were transferred from freshwater (FW) to seawater (SW, 35‰) and from SW to hypersaline SW (2SW, 60‰) in a time course with transfer control groups (FW to FW, and SW to SW). FW to SW transfer increased mRNA abundance of cldn-10d and cldn-10e twofold, whilst cldn-10c and cldn-10f transcripts were unchanged. Transfer from SW to 2SW did not alter cldn-10d, and transiently altered cldn-10e abundance, but increased cldn-10c and cldn-10f fourfold. This was coincident with an increased number of single-stranded junctions (observed by transmission electron microscopy). For both salinity transfers, (1) cldn-10e mRNA was acutely responsive (i.e. after 24 h), (2) other responsive cldn-10 isoforms increased later (3-7 days), and (3) cystic fibrosis transmembrane conductance regulator (cftr) mRNA was elevated in accordance with established changes in transcellular Cl- movement. Changes in mRNA encoding cldn-10c and -10f appeared linked, consistent with the tandem repeat locus in the Fundulus genome, whereas mRNA for tandem cldn-10d and cldn-10e seemed independent of each other. Cation selectivity sequence measured by voltage and conductance responses to artificial SW revealed Eisenman sequence VII: Na+>K+>Rb+∼Cs+>Li+ Collectively, these data support the idea that Cldn-10 TJ proteins create and maintain cation-selective pore junctions in salt-secreting tissues of teleost fishes.
Collapse
Affiliation(s)
- William S Marshall
- Department of Biology, St Francis Xavier University, Antigonish, NS, Canada B2G 2W5
| | - Jason P Breves
- Department of Biology, Skidmore College, Saratoga Springs, NY 12866, USA
| | - Ellen M Doohan
- Department of Biology, St Francis Xavier University, Antigonish, NS, Canada B2G 2W5
| | - Christian K Tipsmark
- Department of Biological Sciences, University of Arkansas, Fayetteville, AK 72701, USA
| | - Scott P Kelly
- Department of Biology, York University, Toronto, ON, Canada M3J 1P3
| | - George N Robertson
- Department of Biology, St Francis Xavier University, Antigonish, NS, Canada B2G 2W5
| | - Patricia M Schulte
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| |
Collapse
|
7
|
Rosenthal R, Günzel D, Theune D, Czichos C, Schulzke JD, Fromm M. Water channels and barriers formed by claudins. Ann N Y Acad Sci 2017. [PMID: 28636801 DOI: 10.1111/nyas.13383] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Physiological studies in leaky epithelia, like kidney proximal tubules and the small intestine, have documented water transport via both transcellular and paracellular pathways. The discovery of aquaporin water channels provided a molecular basis for transcellular water movement. In contrast, the contribution, or even existence, of a specific paracellular water pathway has been disputed for a long time, until the cation channel-forming tight junction protein claudin-2 was shown to also permit the paracellular passage of water through its pore. In proximal kidney tubules, claudin-2-based water transport contributes 23-30% of the total water transport. Other paracellular ion channels (claudin-10a, -10b, and -17) proved to be impermeable to water, although their pore size would be sufficient for water molecules to pass. Studies of barrier-forming claudins, like claudin-1 and claudin-3, which tighten the paracellular pathway against ions and larger solutes, indicate that changes in the expression of these sealing claudins do not influence transepithelial water permeability. The present genetic, molecular, computational, and physiological studies are just now beginning to probe the mechanisms and regulation of paracellular permeation.
Collapse
Affiliation(s)
- Rita Rosenthal
- Institute of Clinical Physiology, Department of Gastroenterology, Rheumatology and Infectious Diseases, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Dorothee Günzel
- Institute of Clinical Physiology, Department of Gastroenterology, Rheumatology and Infectious Diseases, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Dian Theune
- Institute of Clinical Physiology, Department of Gastroenterology, Rheumatology and Infectious Diseases, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Carolina Czichos
- Institute of Clinical Physiology, Department of Gastroenterology, Rheumatology and Infectious Diseases, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Jörg-Dieter Schulzke
- Institute of Clinical Physiology, Department of Gastroenterology, Rheumatology and Infectious Diseases, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Michael Fromm
- Institute of Clinical Physiology, Department of Gastroenterology, Rheumatology and Infectious Diseases, Charité - Universitätsmedizin Berlin, Berlin, Germany
| |
Collapse
|
8
|
Muto S. Physiological roles of claudins in kidney tubule paracellular transport. Am J Physiol Renal Physiol 2017; 312:F9-F24. [DOI: 10.1152/ajprenal.00204.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 10/24/2016] [Accepted: 10/25/2016] [Indexed: 12/30/2022] Open
Abstract
The paracellular pathways in renal tubular epithelia such as the proximal tubules, which reabsorb the largest fraction of filtered solutes and water and are leaky epithelia, are important routes for transepithelial transport of solutes and water. Movement occurs passively via an extracellular route through the tight junction between cells. The characteristics of paracellular transport vary among different nephron segments with leaky or tighter epithelia. Claudins expressed at tight junctions form pores and barriers for paracellular transport. Claudins are from a multigene family, comprising at least 27 members in mammals. Multiple claudins are expressed at tight junctions of individual nephron segments in a nephron segment-specific manner. Over the last decade, there have been advances in our understanding of the structure and functions of claudins. This paper is a review of our current knowledge of claudins, with special emphasis on their physiological roles in proximal tubule paracellular solute and water transport.
Collapse
Affiliation(s)
- Shigeaki Muto
- Division of Nephrology, Department of Internal Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan
| |
Collapse
|
9
|
Tokuda S, Hirai T, Furuse M. Effects of Osmolality on Paracellular Transport in MDCK II Cells. PLoS One 2016; 11:e0166904. [PMID: 27855213 PMCID: PMC5113991 DOI: 10.1371/journal.pone.0166904] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Accepted: 11/04/2016] [Indexed: 12/20/2022] Open
Abstract
Epithelia separate apical and basal compartments, and movement of substances via the paracellular pathway is regulated by tight junctions. Claudins are major constituents of tight junctions and involved in the regulation of tight junction permeability. On the other hand, the osmolality in the extracellular environment fluctuates in association with life activity. However, effects of osmotic changes on the permeaibility of claudins are poorly understood. Therefore, we investigated the effects of osmotic changes on the paracellular transport in MDCK II cells. Interestingly, apical hyposmolality decreased cation selectivity in the paracellular pathway gradually with time, and the elimination of the osmotic gradient promptly restored the cation selectivity. Apical hyposmolality also induced bleb formation at cell-cell contacts and changed the shape of cell-cell contacts from a jagged pattern to a slightly linear pattern. In claudin-2 knockout MDCK II cells, the decrease of cation selectivity, the bleb formation, nor the changes in the shape of cell-cell contacts was observed under the apical hyposmolality. Our findings in this study indicate that osmotic gradient between apical and basal sides is involved in the acute regulation of the cation selective property of claudin-2 channels.
Collapse
Affiliation(s)
- Shinsaku Tokuda
- Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
- * E-mail:
| | - Toyohiro Hirai
- Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Mikio Furuse
- Division of Cell Structure, National Institute for Physiological Sciences, Okazaki, Japan
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki 444–8585, Japan
| |
Collapse
|