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Larsen EH, Sørensen JN. Biophysical Analysis of a Minimalistic Kidney Model Expressing SGLT1 Reveals Crosstalk between Luminal and Lateral Membranes and a Plausible Mechanism of Isosmotic Transport. Biomolecules 2024; 14:889. [PMID: 39199277 PMCID: PMC11352722 DOI: 10.3390/biom14080889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2024] [Revised: 07/17/2024] [Accepted: 07/17/2024] [Indexed: 09/01/2024] Open
Abstract
We extended our model of the S1 tubular segment to address the mechanisms by which SGLT1 interacts with lateral Na/K pumps and tight junctional complexes to generate isosmotic fluid reabsorption via tubular segment S3. The strategy applied allowed for simulation of laboratory experiments. Reproducing known experimental results constrained the range of acceptable model outputs and contributed to minimizing the free parameter space. (1) In experimental conditions, published Na and K concentrations of proximal kidney cells were found to deviate substantially from their normal physiological levels. Analysis of the mechanisms involved suggested insufficient oxygen supply as the cause and, indirectly, that a main function of the Na/H exchanger (NHE3) is to extrude protons stemming from mitochondrial energy metabolism. (2) The water path from the lumen to the peritubular space passed through aquaporins on the cell membrane and claudin-2 at paracellular tight junctions, with an additional contribution to water transport by the coupling of 1 glucose:2 Na:400 H2O in SGLT1. (3) A Na-uptake component passed through paracellular junctions via solvent drag in Na- and water-permeable claudin-2, thus bypassing the Na/K pump, in agreement with the findings of early studies. (4) Electrical crosstalk between apical rheogenic SGLT1 and lateral rheogenic Na/K pumps resulted in tight coupling of luminal glucose uptake and transepithelial water flow. (5) Isosmotic transport was achieved by Na-mediated ion recirculation at the peritubular membrane.
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Affiliation(s)
- Erik Hviid Larsen
- Department of Biology, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Jens Nørkær Sørensen
- Department of Wind Energy, Technical University of Denmark, DK-2800 Lyngby, Denmark;
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Borriello G, Buonincontri V, de Donato A, Della Corte M, Gravina I, Iulianiello P, Joshi R, Mone P, Cacciola G, Viggiano D. The interplay between sodium/glucose cotransporter type 2 and mitochondrial ionic environment. Mitochondrion 2024; 76:101878. [PMID: 38599300 DOI: 10.1016/j.mito.2024.101878] [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: 12/31/2023] [Revised: 03/04/2024] [Accepted: 04/07/2024] [Indexed: 04/12/2024]
Abstract
Mitochondrial volume is maintained through the permeability of the inner mitochondrial membrane by a specific aquaporin and the osmotic balance between the mitochondrial matrix and cellular cytoplasm. Various electrolytes, such as calcium and hydrogen ions, potassium, and sodium, as well as other osmotic substances, affect the swelling of mitochondria. Intracellular glucose levels may also affect mitochondrial swelling, although the relationship between mitochondrial ion homeostasis and intracellular glucose is poorly understood. This article reviews what is currently known about how the Sodium-Glucose transporter (SGLT) may impact mitochondrial sodium (Na+) homeostasis. SGLTs regulate intracellular glucose and sodium levels and, therefore, interfere with mitochondrial ion homeostasis because mitochondrial Na+ is closely linked to cytoplasmic calcium and sodium dynamics. Recently, a large amount of data has been available on the effects of SGLT2 inhibitors on mitochondria in different cell types, including renal proximal tubule cells, endothelial cells, mesangial cells, podocytes, neuronal cells, and cardiac cells. The current evidence suggests that SGLT inhibitors (SGLTi) may affect mitochondrial dynamics regarding intracellular Sodium and hydrogen ions. Although the regulation of mitochondrial ion channels by SGLTs is still in its infancy, the evidence accumulated thus far of the effect of SGLTi on mitochondrial functions certainly will foster further research in this direction.
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Affiliation(s)
- Gianmarco Borriello
- Dept. Translational Medical Sciences, Univ. Campania, "L Vanvitelli", Naples, Italy
| | | | - Antonio de Donato
- Biogem, Biology and Molecular Genetics Institute, Ariano Irpino, AV, Italy
| | - Michele Della Corte
- Dept. Translational Medical Sciences, Univ. Campania, "L Vanvitelli", Naples, Italy
| | - Ilenia Gravina
- Dept. Translational Medical Sciences, Univ. Campania, "L Vanvitelli", Naples, Italy
| | - Pietro Iulianiello
- Dept. Translational Medical Sciences, Univ. Campania, "L Vanvitelli", Naples, Italy
| | - Rashmi Joshi
- Dept. Translational Medical Sciences, Univ. Campania, "L Vanvitelli", Naples, Italy
| | - Pasquale Mone
- Department of Medicine and Health Sciences, University of Molise, Campobasso, Italy; Casa di cura privata Montevergine, Mercogliano, Italy
| | - Giovanna Cacciola
- Dept. Translational Medical Sciences, Univ. Campania, "L Vanvitelli", Naples, Italy
| | - Davide Viggiano
- Dept. Translational Medical Sciences, Univ. Campania, "L Vanvitelli", Naples, Italy.
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Bagnat M, Daga B, Di Talia S. Morphogenetic Roles of Hydrostatic Pressure in Animal Development. Annu Rev Cell Dev Biol 2022; 38:375-394. [PMID: 35804476 PMCID: PMC9675319 DOI: 10.1146/annurev-cellbio-120320-033250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
During organismal development, organs and systems are built following a genetic blueprint that produces structures capable of performing specific physiological functions. Interestingly, we have learned that the physiological activities of developing tissues also contribute to their own morphogenesis. Specifically, physiological activities such as fluid secretion and cell contractility generate hydrostatic pressure that can act as a morphogenetic force. Here, we first review the role of hydrostatic pressure in tube formation during animal development and discuss mathematical models of lumen formation. We then illustrate specific roles of the notochord as a hydrostatic scaffold in anterior-posterior axis development in chordates. Finally, we cover some examples of how fluid flows influence morphogenetic processes in other developmental contexts. Understanding how fluid forces act during development will be key for uncovering the self-organizing principles that control morphogenesis.
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Affiliation(s)
- Michel Bagnat
- Department of Cell Biology, Duke University, Durham, North Carolina, USA;
| | - Bijoy Daga
- Department of Cell Biology, Duke University, Durham, North Carolina, USA;
| | - Stefano Di Talia
- Department of Cell Biology, Duke University, Durham, North Carolina, USA;
- Department of Orthopaedic Surgery, Duke University, Durham, North Carolina, USA
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Hill DB, Button B, Rubinstein M, Boucher RC. Physiology and pathophysiology of human airway mucus. Physiol Rev 2022; 102:1757-1836. [PMID: 35001665 PMCID: PMC9665957 DOI: 10.1152/physrev.00004.2021] [Citation(s) in RCA: 90] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 12/13/2021] [Accepted: 12/19/2021] [Indexed: 01/27/2023] Open
Abstract
The mucus clearance system is the dominant mechanical host defense system of the human lung. Mucus is cleared from the lung by cilia and airflow, including both two-phase gas-liquid pumping and cough-dependent mechanisms, and mucus transport rates are heavily dependent on mucus concentration. Importantly, mucus transport rates are accurately predicted by the gel-on-brush model of the mucociliary apparatus from the relative osmotic moduli of the mucus and periciliary-glycocalyceal (PCL-G) layers. The fluid available to hydrate mucus is generated by transepithelial fluid transport. Feedback interactions between mucus concentrations and cilia beating, via purinergic signaling, coordinate Na+ absorptive vs Cl- secretory rates to maintain mucus hydration in health. In disease, mucus becomes hyperconcentrated (dehydrated). Multiple mechanisms derange the ion transport pathways that normally hydrate mucus in muco-obstructive lung diseases, e.g., cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), non-CF bronchiectasis (NCFB), and primary ciliary dyskinesia (PCD). A key step in muco-obstructive disease pathogenesis is the osmotic compression of the mucus layer onto the airway surface with the formation of adherent mucus plaques and plugs, particularly in distal airways. Mucus plaques create locally hypoxic conditions and produce airflow obstruction, inflammation, infection, and, ultimately, airway wall damage. Therapies to clear adherent mucus with hydrating and mucolytic agents are rational, and strategies to develop these agents are reviewed.
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Affiliation(s)
- David B Hill
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Joint Department of Biomedical Engineering, The University of North Carolina and North Carolina State University, Chapel Hill, North Carolina
| | - Brian Button
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Michael Rubinstein
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Department of Mechanical Engineering and Materials Science, Biomedical Engineering, Physics, and Chemistry, Duke University, Durham, North Carolina
| | - Richard C Boucher
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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Peters WS, Knoblauch M. How Münch's adaptation of Pfeffer's circulating water flow became the pressure-flow theory, and the resulting problems - A historical perspective. JOURNAL OF PLANT PHYSIOLOGY 2022; 272:153672. [PMID: 35366573 DOI: 10.1016/j.jplph.2022.153672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 03/16/2022] [Accepted: 03/17/2022] [Indexed: 06/14/2023]
Abstract
Long-distance transport of photoassimilates in the phloem of vascular plants occurs as bulk flow in sieve tubes. These tubes are arrays of cells that lose nuclei, cytoskeleton, and some organelles when they differentiate into mature sieve elements. Symplasmic continuity is achieved by perforations that turn the cell walls between adjoining sieve elements into sieve plates. These structural features are interpreted as adaptations that reduce the resistance sieve tubes offer to cytoplasmic bulk flow. According to the common reading of Ernst Münch's pressure-flow theory, the driving forces for these flows are osmotically generated gradients of hydrostatic pressure along the sieve tubes. However, the significance of pressure gradients in the flow direction has also been questioned. Münch himself stated that no detectable pressure gradients existed between the linked osmotic cells that he used to demonstrate the validity of his ideas, and the earliest explanation of osmotically driven flows by Wilhelm Pfeffer, on which Münch based his theory, explicitly claimed the absence of pressure gradients. To resolve the apparent contradiction, we here reconstruct the history of the idea that osmotically driven transport processes in organisms necessarily require steps or gradients of hydrostatic pressure along the transport route. Our analysis leads us to conclude that some defects of overly simplifying interpretations of Münch's ideas (such as the sieve plate fallacy) could be avoided if our descriptions of his theory in textbooks and the scientific literature would follow the logics of the theory's earliest formulations more closely.
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Affiliation(s)
- Winfried S Peters
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA; Department of Biology, Purdue University Fort Wayne, Fort Wayne, IN, 46805, USA.
| | - Michael Knoblauch
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA.
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Larsen EH, Sørensen JN. Ion and Water Absorption by the Kidney Proximal Tubule: Computational Analysis of Isosmotic Transport. FUNCTION (OXFORD, ENGLAND) 2020; 1:zqaa014. [PMID: 35330635 PMCID: PMC8788719 DOI: 10.1093/function/zqaa014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 08/21/2020] [Accepted: 08/25/2020] [Indexed: 01/06/2023]
Affiliation(s)
- Erik H Larsen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark,Address correspondence to E.H.L. (e-mail: )
| | - Jens N Sørensen
- Department of Wind Energy, Technical University of Denmark, Lyngby, Denmark
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