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Zhang C, Feng L, Wu P, Liu Y, Jin X, Ren H, Li H, Wu F, Zhou X, Jiang W. Establishing the link between D-mannose and juvenile grass carp ( Ctenopharyngodon idella): Improved growth and intestinal structure associated with endoplasmic reticulum stress, mitophagy, and apical junctional complexes. ANIMAL NUTRITION (ZHONGGUO XU MU SHOU YI XUE HUI) 2024; 18:450-463. [PMID: 39315328 PMCID: PMC11417208 DOI: 10.1016/j.aninu.2024.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 02/21/2024] [Accepted: 05/06/2024] [Indexed: 09/25/2024]
Abstract
D-mannose, essential for protein glycosylation, has been reported to have immunomodulatory effects and to maintain intestinal flora homeostasis. In addition to evaluating growth performance, we examined the impact of D-mannose on the structure of epithelial cells and apical junction complexes in the animal intestine. All 1800 grass carp (16.20 ± 0.01 g) were randomly divided into six treatments with six replicates of 50 fish each and fed with six different levels of D-mannose (0.52, 1.75, 3.02, 4.28, 5.50 and 6.78 g/kg diet) for 70 d. The study revealed that D-mannose increased feed intake (P < 0.001) but did not affect the percent weight gain (PWG), special growth rate, and feed conversion ratio (P > 0.05). D-mannose supplementation at 1.75 g/kg increased crude protein content in fish and lipid production value (P < 0.05). D-mannose supplementation at 4.28 g/kg increased intestinal length, intestinal weight and fold height of grass carp compared to the control group (P < 0.05). This improvement may be attributed to the phosphomannose isomerase (PMI)-mediated enhancement of glycolysis. This study found that D-mannose supplementation at 4.28 or 3.02 g/kg reduced serum diamine oxidase activity or D-lactate content (P < 0.05) and improved cellular and intercellular structures for the first time. The improvement of cellular redox homeostasis involves alleviating endoplasmic reticulum (ER) stress through the inositol-requiring enzyme 1 (IRE1), RNA-dependent protein kinase-like ER kinase (PERK), and activating transcription factor 6 (ATF6) signaling pathways. The alleviation of ER stress may be linked to the phosphomannomutase (PMM)-mediated enhancement of protein glycosylation. In addition, ubiquitin-dependent [PTEN-induced putative kinase 1 (PINK1)/Parkin] and ubiquitin-independent [BCL2-interacting protein 3-like (BNIP3L), BCL2-interacting protein 3 (BNIP3), and FUN14 domain containing 1 (FUNDC1)] mitophagy may play a role in maintaining cellular redox homeostasis. The enhancement of intercellular structures includes enhancing tight junction and adherent junction structures, which may be closely associated with the small Rho GTPase protein (RhoA)/the Rho-associated protein kinase (ROCK) signaling pathway. In conclusion, D-mannose improved intestinal cellular redox homeostasis associated with ER stress and mitophagy pathways, and enhanced intercellular structures related to tight junctions and adherent junctions. Furthermore, quadratic regression analysis of the PWG and intestinal reactive oxygen species content indicated that the optimal addition level of D-mannose for juvenile grass carp was 4.61 and 4.59 g/kg, respectively.
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Affiliation(s)
- Chong Zhang
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China
| | - Lin Feng
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China
- Fish Nutrition and Safety Production, University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
- Key Laboratory of Animal Disease-Resistance Nutrition, Ministry of Education, Ministry of Agriculture and Rural Affairs, Key Laboratory of Sichuan Province, Chengdu 611130, China
| | - Pei Wu
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China
- Fish Nutrition and Safety Production, University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
- Key Laboratory of Animal Disease-Resistance Nutrition, Ministry of Education, Ministry of Agriculture and Rural Affairs, Key Laboratory of Sichuan Province, Chengdu 611130, China
| | - Yang Liu
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China
- Fish Nutrition and Safety Production, University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
- Key Laboratory of Animal Disease-Resistance Nutrition, Ministry of Education, Ministry of Agriculture and Rural Affairs, Key Laboratory of Sichuan Province, Chengdu 611130, China
| | - Xiaowan Jin
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China
| | - Hongmei Ren
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China
| | - Hua Li
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China
| | - Fali Wu
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China
| | - Xiaoqiu Zhou
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China
- Fish Nutrition and Safety Production, University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
- Key Laboratory of Animal Disease-Resistance Nutrition, Ministry of Education, Ministry of Agriculture and Rural Affairs, Key Laboratory of Sichuan Province, Chengdu 611130, China
| | - Weidan Jiang
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China
- Fish Nutrition and Safety Production, University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
- Key Laboratory of Animal Disease-Resistance Nutrition, Ministry of Education, Ministry of Agriculture and Rural Affairs, Key Laboratory of Sichuan Province, Chengdu 611130, China
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2
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Yu ASL, Curry JN. Paracellular Transport and Renal Tubule Calcium Handling: Emerging Roles in Kidney Stone Disease. J Am Soc Nephrol 2024:00001751-990000000-00411. [PMID: 39207856 DOI: 10.1681/asn.0000000506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Accepted: 08/26/2024] [Indexed: 09/04/2024] Open
Abstract
The kidney plays a major role in maintenance of serum calcium concentration, which must be kept within a narrow range to avoid disruption of numerous physiologic processes that depend critically on the level of extracellular calcium, including cell signaling, bone structure, and muscle and nerve function. This defense of systemic calcium homeostasis comes, however, at the expense of the dumping of calcium into the kidney tissue and urine. Because of the large size and multivalency of the calcium ion, its salts are the least soluble among all the major cations in the body. The potential pathologic consequences of this are nephrocalcinosis and kidney stone disease. In this review, we discuss recent advances that have highlighted critical roles for the proximal tubule and thick ascending limb in renal calcium reabsorption, elucidated the molecular mechanisms for paracellular transport in these segments, and implicated disturbances in these processes in human disease.
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Affiliation(s)
- Alan S L Yu
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas
| | - Joshua N Curry
- Division of Nephrology, Oregon Health Sciences University, Portland, Oregon
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3
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Marsch P, Rajagopal N, Nangia S. Biophysics of claudin proteins in tight junction architecture: Three decades of progress. Biophys J 2024; 123:2363-2378. [PMID: 38859584 PMCID: PMC11365114 DOI: 10.1016/j.bpj.2024.06.010] [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: 01/17/2024] [Revised: 05/19/2024] [Accepted: 06/07/2024] [Indexed: 06/12/2024] Open
Abstract
Tight junctions are cell-cell adhesion complexes that act as gatekeepers of the paracellular space. Formed by several transmembrane proteins, the claudin family performs the primary gate-keeping function. The claudin proteins form charge and size-selective diffusion barriers to maintain homeostasis across endothelial and epithelial tissue. Of the 27 known claudins in mammals, some are known to seal the paracellular space, while others provide selective permeability. The differences in permeability arise due to the varying expression levels of claudins in each tissue. The tight junctions are observed as strands in freeze-fracture electron monographs; however, at the molecular level, tight junction strands form when multiple claudin proteins assemble laterally (cis assembly) within a cell and head-on (trans assembly) with claudins of the adjacent cell in a zipper-like architecture, closing the gap between the neighboring cells. The disruption of tight junctions caused by changing claudin expression levels or mutations can lead to diseases. Therefore, knowledge of the molecular architecture of the tight junctions and how that is tied to tissue-specific function is critical for fighting diseases. Here, we review the current understanding of the tight junctions accrued over the last three decades from experimental and computational biophysics perspectives.
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Affiliation(s)
- Patrick Marsch
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York
| | - Nandhini Rajagopal
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York
| | - Shikha Nangia
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York.
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4
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Apostolova D, Apostolov G, Moten D, Batsalova T, Dzhambazov B. Claudin-12: guardian of the tissue barrier or friend of tumor cells. Tissue Barriers 2024:2387408. [PMID: 39087432 DOI: 10.1080/21688370.2024.2387408] [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: 05/04/2024] [Revised: 07/28/2024] [Accepted: 07/28/2024] [Indexed: 08/02/2024] Open
Abstract
Tight junctions (TJs) are an important component of cellular connectivity. Claudin family proteins, as a constituent of TJs, determine their barrier properties, cell polarity and paracellular permeability. Claudin-12 is an atypical member of the claudin family, as it belongs to the group of non-classical claudins that lack a PDZ-binding domain. It has been shown that claudin-12 is involved in paracellular Ca2+ transients and it is present in normal and hyperplastic tissues in addition to neoplastic tissues. Dysregulation of claudin-12 expression has been reported in various cancers, suggesting that this protein may play an important role in cancer cell migration, invasion, and metastasis. Some studies have shown that claudin-12 gene functions as a tumor suppressor, but others have reported that overexpression of claudin-12 significantly increases the metastatic properties of various tumor cells. Investigating this dual role of claudin-12 is of utmost importance and should therefore be studied in detail. The aim of this review is to provide an overview of the information available to date on claudin-12, including its structure, expression in various tissues and substances that may affect it, with a final focus on its role in cancer.
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Affiliation(s)
- Desislava Apostolova
- Department of Developmental Biology, Faculty of Biology, Paisii Hilendarski University of Plovdiv, Plovdiv, Bulgaria
| | - Georgi Apostolov
- Department of Neurosurgery, Faculty of Medicine, Medical University of Plovdiv, Plovdiv, Bulgaria
| | - Dzhemal Moten
- Department of Developmental Biology, Faculty of Biology, Paisii Hilendarski University of Plovdiv, Plovdiv, Bulgaria
| | - Tsvetelina Batsalova
- Department of Developmental Biology, Faculty of Biology, Paisii Hilendarski University of Plovdiv, Plovdiv, Bulgaria
| | - Balik Dzhambazov
- Department of Developmental Biology, Faculty of Biology, Paisii Hilendarski University of Plovdiv, Plovdiv, Bulgaria
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Staruschenko A, Alexander RT, Caplan MJ, Ilatovskaya DV. Calcium signalling and transport in the kidney. Nat Rev Nephrol 2024; 20:541-555. [PMID: 38641658 DOI: 10.1038/s41581-024-00835-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/27/2024] [Indexed: 04/21/2024]
Abstract
The kidney plays a pivotal role in regulating calcium levels within the body. Approximately 98% of the filtered calcium is reabsorbed in the nephron, and this process is tightly controlled to maintain calcium homeostasis, which is required to facilitate optimal bone mineralization, preserve serum calcium levels within a narrow range, and support intracellular signalling mechanisms. The maintenance of these functions is attributed to a delicate balance achieved by various calcium channels, transporters, and calcium-binding proteins in renal cells. Perturbation of this balance due to deficiency or dysfunction of calcium channels and calcium-binding proteins can lead to severe complications. For example, polycystic kidney disease is linked to aberrant calcium transport and signalling. Furthermore, dysregulation of calcium levels can promote the formation of kidney stones. This Review provides an updated description of the key aspects of calcium handling in the kidney, focusing on the function of various calcium channels and the physiological stimuli that control these channels or are communicated through them. A discussion of the role of calcium as an intracellular second messenger and the pathophysiology of renal calcium dysregulation, as well as a summary of gaps in knowledge and future prospects, are also included.
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Affiliation(s)
- Alexander Staruschenko
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, FL, USA.
- Hypertension and Kidney Research Center, University of South Florida, Tampa, FL, USA.
- James A. Haley Veterans Hospital, Tampa, FL, USA.
| | - R Todd Alexander
- Department of Paediatrics, University of Alberta, Edmonton, AB, Canada
- Women's and Children's Health Institute, Edmonton, AB, Canada
| | - Michael J Caplan
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA
| | - Daria V Ilatovskaya
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA, USA
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Khan N, Kurnik-Łucka M, Latacz G, Gil K. Systematic-Narrative Hybrid Literature Review: Crosstalk between Gastrointestinal Renin-Angiotensin and Dopaminergic Systems in the Regulation of Intestinal Permeability by Tight Junctions. Int J Mol Sci 2024; 25:5566. [PMID: 38791603 PMCID: PMC11122119 DOI: 10.3390/ijms25105566] [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: 04/17/2024] [Revised: 05/12/2024] [Accepted: 05/18/2024] [Indexed: 05/26/2024] Open
Abstract
In the first part of this article, the role of intestinal epithelial tight junctions (TJs), together with gastrointestinal dopaminergic and renin-angiotensin systems, are narratively reviewed to provide sufficient background. In the second part, the current experimental data on the interplay between gastrointestinal (GI) dopaminergic and renin-angiotensin systems in the regulation of intestinal epithelial permeability are reviewed in a systematic manner using the PRISMA methodology. Experimental data confirmed the copresence of DOPA decarboxylase (DDC) and angiotensin converting enzyme 2 (ACE2) in human and rodent enterocytes. The intestinal barrier structure and integrity can be altered by angiotensin (1-7) and dopamine (DA). Both renin-angiotensin and dopaminergic systems influence intestinal Na+/K+-ATPase activity, thus maintaining electrolyte and nutritional homeostasis. The colocalization of B0AT1 and ACE2 indicates the direct role of the renin-angiotensin system in amino acid absorption. Yet, more studies are needed to thoroughly define the structural and functional interaction between TJ-associated proteins and GI renin-angiotensin and dopaminergic systems.
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Affiliation(s)
- Nadia Khan
- Faculty of Medicine, Department of Pathophysiology, Jagiellonian University Medical College, Czysta 18, 31-121 Krakow, Poland
- Faculty of Pharmacy, Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, Medyczna 9, 31-008 Krakow, Poland
| | - Magdalena Kurnik-Łucka
- Faculty of Medicine, Department of Pathophysiology, Jagiellonian University Medical College, Czysta 18, 31-121 Krakow, Poland
| | - Gniewomir Latacz
- Faculty of Pharmacy, Department of Technology and Biotechnology of Drugs, Jagiellonian University Medical College, Medyczna 9, 31-008 Krakow, Poland
| | - Krzysztof Gil
- Faculty of Medicine, Department of Pathophysiology, Jagiellonian University Medical College, Czysta 18, 31-121 Krakow, Poland
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7
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Tan RSG, Lee CHL, Pan W, Wohlgemuth S, Doschak MR, Alexander RT. Disruption of the c-terminal serine protease domain of Fam111a does not alter calcium homeostasis in mice. Physiol Rep 2024; 12:e15977. [PMID: 38697929 PMCID: PMC11065693 DOI: 10.14814/phy2.15977] [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: 12/31/2023] [Revised: 02/28/2024] [Accepted: 03/01/2024] [Indexed: 05/05/2024] Open
Abstract
FAM111A gene mutations cause Kenney-Caffey syndrome (KCS) and Osteocraniostenosis (OCS), conditions characterized by short stature, low serum ionized calcium (Ca2+), low parathyroid hormone (PTH), and bony abnormalities. The molecular mechanism mediating this phenotype is unknown. The c-terminal domain of FAM111A harbors all the known disease-causing variations and encodes a domain with high homology to serine proteases. However, whether this serine protease domain contributes to the maintenance of Ca2+ homeostasis is not known. We hypothesized the disruption of the serine protease domain of FAM111A would disrupt Ca2+ homeostasis. To test this hypothesis, we generated with CRISPR/Cas9, mice with a frameshift insertion (c.1450insA) or large deletion (c.1253-1464del) mutation in the Fam111a serine protease domain. Serum-ionized Ca2+ and PTH levels were not significantly different between wild type, heterozygous, or homozygous Fam111a mutant mice. Additionally, there were no significant differences in fecal or urine Ca2+ excretion, intestinal Ca2+ absorption or overall Ca2+ balance. Only female homozygous (c.1450insA), but not heterozygous mice displayed differences in bone microarchitecture and mineral density compared to wild-type animals. We conclude that frameshift mutations that disrupt the c-terminal serine protease domain do not induce a KCS or OCS phenotype in mice nor alter Ca2+ homeostasis.
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Affiliation(s)
- Rebecca Siu Ga Tan
- Department of PhysiologyUniversity of AlbertaEdmontonAlbertaCanada
- Membrane Protein Disease Research GroupUniversity of AlbertaEdmontonAlbertaCanada
- The Women and Children's Health Research InstituteEdmontonAlbertaCanada
| | - Christy Hui Lin Lee
- Department of PhysiologyUniversity of AlbertaEdmontonAlbertaCanada
- Membrane Protein Disease Research GroupUniversity of AlbertaEdmontonAlbertaCanada
- The Women and Children's Health Research InstituteEdmontonAlbertaCanada
| | - Wanling Pan
- Department of PhysiologyUniversity of AlbertaEdmontonAlbertaCanada
- Membrane Protein Disease Research GroupUniversity of AlbertaEdmontonAlbertaCanada
| | | | - Michael R. Doschak
- Faculty of Pharmacy & Pharmaceutical SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | - R. Todd Alexander
- Department of PhysiologyUniversity of AlbertaEdmontonAlbertaCanada
- Membrane Protein Disease Research GroupUniversity of AlbertaEdmontonAlbertaCanada
- The Women and Children's Health Research InstituteEdmontonAlbertaCanada
- Department of PediatricsUniversity of AlbertaEdmontonAlbertaCanada
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8
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Shah CV, Sparks MA, Lee CT. Sodium/Glucose Cotransporter 2 Inhibitors and Magnesium Homeostasis: A Review. Am J Kidney Dis 2024; 83:648-658. [PMID: 38372686 DOI: 10.1053/j.ajkd.2023.11.006] [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: 08/08/2023] [Revised: 10/21/2023] [Accepted: 11/11/2023] [Indexed: 02/20/2024]
Abstract
Magnesium (Mg2+), also known as "the forgotten ion," is the second most abundant intracellular cation and is essential in a broad range of intracellular physiological and biochemical reactions. Its deficiency, hypomagnesemia (Mg2+<1.8mg/dL), is a prevalent condition and routinely poses challenges in its management in clinical practice. Sodium/glucose cotransporter 2 (SGLT2) inhibitors have emerged as a new class of drugs with treating hypomagnesemia as their unique extraglycemic benefit. The beneficial effect of SGLT2 inhibitors on magnesium balance in patients with diabetes with or without hypomagnesemia has been noted as a class effect in recent meta-analysis data from randomized clinical trials. Some reports have demonstrated their role in treating refractory hypomagnesemia in patients with or without diabetes. Moreover, studies on animal models have attempted to illustrate the effect of SGLT2 inhibitors on Mg2+homeostasis. In this review, we discuss the current evidence and possible pathophysiological mechanisms, and we provide directions for further research. We conclude by suggesting the effect of SGLT2 inhibitors on Mg2+homeostasis is a class effect, with certain patients gaining significant benefits. Further studies are needed to examine whether SGLT2 inhibitors can become a desperately needed novel class of medicines in treating hypomagnesemia.
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Affiliation(s)
- Chintan V Shah
- Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida, Gainesville, Florida.
| | - Matthew A Sparks
- Division of Nephrology and Department of Medicine, Duke University, and Durham VA Health Care System, Durham, North Carolina
| | - Chien-Te Lee
- Division of Nephrology, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital and Kaohsiung Municipal Feng-Shan Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan
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Kudryavtseva O, Lyngsø KS, Jensen BL, Dimke H. Nitric oxide, endothelium-derived hyperpolarizing factor, and smooth muscle-dependent mechanisms contribute to magnesium-dependent vascular relaxation in mouse arteries. Acta Physiol (Oxf) 2024; 240:e14096. [PMID: 38258597 DOI: 10.1111/apha.14096] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 09/27/2023] [Accepted: 01/01/2024] [Indexed: 01/24/2024]
Abstract
AIM Magnesium (Mg2+ ) is a vasorelaxant. The underlying physiological mechanisms driving this vasorelaxation remain unclear. Studies were designed to test the hypothesis that multiple signaling pathways including nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF) in endothelial cells as well as Ca2+ antagonization and TRPM7 channels in vascular smooth muscle cells mediate Mg2+ -dependent vessel relaxation. METHODS To uncover these mechanisms, force development was measured ex vivo in aorta rings from mice using isometric wire myography. Concentration responses to Mg2+ were studied in intact and endothelium-denuded aortas. Key findings were confirmed in second-order mesenteric resistance arteries perfused ex vivo using pressure myography. Effects of Mg2+ on NO formation were measured in Chinese Hamster Ovary (CHO) cells, isolated mesenteric vessels, and mouse urine. RESULTS Mg2+ caused a significant concentration-dependent relaxation of aorta rings. This relaxation was attenuated significantly in endothelium-denuded aortas. The endothelium-dependent portion was inhibited by NO and cGMP blockade but not by cyclooxygenase inhibition. Mg2+ stimulated local NO formation in CHO cells and isolated mesenteric vessels without changing urinary NOx levels. High extracellular Mg2+ augmented acetylcholine-induced relaxation. SKCa and IKCa channel blockers apamin and TRAM34 inhibited Mg2+ -dependent relaxation. The endothelium-independent relaxation in aorta rings was inhibited by high extracellular Ca2+ . Combined blockade of NO, SKCa , and IKCa channels significantly reduced Mg2+ -dependent dilatation in mesenteric resistance vessels. CONCLUSIONS In mouse conductance and resistance arteries Mg2+ -induced relaxation is contributed by endothelial NO formation, EDHF pathways, antagonism of Ca2+ in smooth muscle cells, and additional unidentified mechanisms.
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Affiliation(s)
- Olga Kudryavtseva
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense C, Denmark
| | - Kristina S Lyngsø
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense C, Denmark
| | - Boye L Jensen
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense C, Denmark
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense C, Denmark
- Department of Nephrology, Odense University Hospital, Odense, Denmark
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Schneemann M, Heils L, Moos V, Weiß F, Krug SM, Weiner J, Beule D, Gerhard R, Schulzke JD, Bücker R. A Colonic Organoid Model Challenged with the Large Toxins of Clostridioides difficile TcdA and TcdB Exhibit Deregulated Tight Junction Proteins. Toxins (Basel) 2023; 15:643. [PMID: 37999506 PMCID: PMC10674794 DOI: 10.3390/toxins15110643] [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: 10/05/2023] [Revised: 10/25/2023] [Accepted: 11/01/2023] [Indexed: 11/25/2023] Open
Abstract
BACKGROUND Clostridioides difficile toxins TcdA and TcdB are responsible for diarrhea and colitis. Lack of functional studies in organoid models of the gut prompted us to elucidate the toxin's effects on epithelial barrier function and the molecular mechanisms for diarrhea and inflammation. METHODS Human adult colon organoids were cultured on membrane inserts. Tight junction (TJ) proteins and actin cytoskeleton were analyzed for expression via Western blotting and via confocal laser-scanning microscopy for subcellular localization. RESULTS Polarized intestinal organoid monolayers were established from stem cell-containing colon organoids to apply toxins from the apical side and to perform functional measurements in the organoid model. The toxins caused a reduction in transepithelial electrical resistance in human colonic organoid monolayers with sublethal concentrations. Concomitantly, we detected increased paracellular permeability fluorescein and FITC-dextran-4000. Human colonic organoid monolayers exposed to the toxins exhibited redistribution of barrier-forming TJ proteins claudin-1, -4 and tricellulin, whereas channel-forming claudin-2 expression was increased. Perijunctional F-actin cytoskeleton organization was affected. CONCLUSIONS Adult stem cell-derived human colonic organoid monolayers were applicable as a colon infection model for electrophysiological measurements. The TJ changes noted can explain the epithelial barrier dysfunction and diarrhea in patients, as well as increased entry of luminal antigens triggering inflammation.
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Affiliation(s)
- Martina Schneemann
- Clinical Physiology, Nutritional Medicine, Charité—Universitätsmedizin Berlin, Campus Benjamin Franklin, 12203 Berlin, Germany
| | - Lucas Heils
- Clinical Physiology, Nutritional Medicine, Charité—Universitätsmedizin Berlin, Campus Benjamin Franklin, 12203 Berlin, Germany
| | - Verena Moos
- Department of Gastroenterology, Infectious Diseases and Rheumatology, Charité—Universitätsmedizin Berlin, Campus Benjamin Franklin, 12203 Berlin, Germany
| | - Franziska Weiß
- Clinical Physiology, Nutritional Medicine, Charité—Universitätsmedizin Berlin, Campus Benjamin Franklin, 12203 Berlin, Germany
| | - Susanne M. Krug
- Clinical Physiology, Nutritional Medicine, Charité—Universitätsmedizin Berlin, Campus Benjamin Franklin, 12203 Berlin, Germany
| | - January Weiner
- Core Unit Bioinformatics (CUBI), Berlin Institute of Health at Charité—Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Dieter Beule
- Core Unit Bioinformatics (CUBI), Berlin Institute of Health at Charité—Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Ralf Gerhard
- Institute of Toxicology, Hannover Medical School, 30625 Hannover, Germany
| | - Jörg-Dieter Schulzke
- Clinical Physiology, Nutritional Medicine, Charité—Universitätsmedizin Berlin, Campus Benjamin Franklin, 12203 Berlin, Germany
| | - Roland Bücker
- Clinical Physiology, Nutritional Medicine, Charité—Universitätsmedizin Berlin, Campus Benjamin Franklin, 12203 Berlin, Germany
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11
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MacDonald T, Beggs MR, O'Neill D, Kozuka K, Dimke H, Alexander RT. Increased Slc34a2 expression and paracellular phosphate permeability contribute to high intestinal phosphate absorption in young mice. Acta Physiol (Oxf) 2023; 239:e14029. [PMID: 37563989 DOI: 10.1111/apha.14029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 07/26/2023] [Accepted: 07/27/2023] [Indexed: 08/12/2023]
Abstract
AIM Phosphorus is a critical constituent of bone as a component of hydroxyapatite. Bone mineral content accrues rapidly early in life necessitating a positive phosphorus balance, which could be established by a combination of increased renal reabsorption and intestinal absorption. Intestinal absorption can occur via a transcellular pathway mediated by the apical sodium-phosphate cotransporter, Slc34a2/NaPiIIb or via the paracellular pathway. We sought to determine how young mammals increase dietary phosphorus absorption from the small intestine to establish a positive phosphorus balance, a prerequisite for rapid bone growth. METHODS The developmental expression profile of genes mediating phosphate absorption from the small intestine was determined in mice by qPCR and immunohistochemistry. Additionally, Ussing chamber studies were performed on small bowel of young (p7-p14) and older (8- to 17-week-old) mice to examine developmental changes in paracellular Pi permeability and transcellular Pi transport. RESULTS Blood and urinary Pi levels were higher in young mice. Intestinal paracellular phosphate permeability of young mice was significantly increased relative to older mice across all intestinal segments. NaPiIIb expression was markedly increased in juvenile mice, in comparison to adult animals. Consistent with this, young mice had increased transcellular phosphate flux across the jejunum and ileum relative to older animals. Moreover, transcellular phosphate transport was attenuated by the NaPiIIb inhibitor NTX1942 in the jejunum and ileum of young mice. CONCLUSION Our results are consistent with young mice increasing phosphate absorption via increasing paracellular permeability and the NaPiIIb-mediated transcellular pathway.
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Affiliation(s)
- Tate MacDonald
- Department of Physiology, The University of Alberta, Edmonton, Alberta, Canada
- The Women and Children's Health Research Institute, Edmonton, Alberta, Canada
| | - Megan R Beggs
- Department of Physiology, The University of Alberta, Edmonton, Alberta, Canada
- The Women and Children's Health Research Institute, Edmonton, Alberta, Canada
| | - Debbie O'Neill
- Department of Physiology, The University of Alberta, Edmonton, Alberta, Canada
| | | | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
- Department of Nephrology, Odense University Hospital, Odense, Denmark
| | - R Todd Alexander
- Department of Physiology, The University of Alberta, Edmonton, Alberta, Canada
- The Women and Children's Health Research Institute, Edmonton, Alberta, Canada
- Department of Pediatrics, The University of Alberta, Edmonton, Alberta, Canada
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12
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Abstract
Sequential expression of claudins, a family of tight junction proteins, along the nephron mirrors the sequential expression of ion channels and transporters. Only by the interplay of transcellular and paracellular transport can the kidney efficiently maintain electrolyte and water homeostasis in an organism. Although channel and transporter defects have long been known to perturb homeostasis, the contribution of individual tight junction proteins has been less clear. Over the past two decades, the regulation and dysregulation of claudins have been intensively studied in the gastrointestinal tract. Claudin expression patterns have, for instance, been found to be affected in infection and inflammation, or in cancer. In the kidney, a deeper understanding of the causes as well as the effects of claudin expression alterations is only just emerging. Little is known about hormonal control of the paracellular pathway along the nephron, effects of cytokines on renal claudin expression or relevance of changes in paracellular permeability to the outcome in any of the major kidney diseases. By summarizing current findings on the role of specific claudins in maintaining electrolyte and water homeostasis, this Review aims to stimulate investigations on claudins as prognostic markers or as druggable targets in kidney disease.
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Affiliation(s)
- Luca Meoli
- Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology, Rheumatology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Dorothee Günzel
- Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology, Rheumatology, Charité - Universitätsmedizin Berlin, Berlin, Germany.
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13
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Chen JTC, Hu X, Otto IUC, Schürger C, von Bieberstein BR, Doppler K, Krug SM, Hankir MK, Blasig R, Sommer C, Brack A, Blasig IE, Rittner HL. Myelin barrier breakdown, mechanical hypersensitivity, and painfulness in polyneuropathy with claudin-12 deficiency. Neurobiol Dis 2023; 185:106246. [PMID: 37527762 DOI: 10.1016/j.nbd.2023.106246] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 05/25/2023] [Accepted: 07/28/2023] [Indexed: 08/03/2023] Open
Abstract
BACKGROUND The blood-nerve and myelin barrier shield peripheral neurons and their axons. These barriers are sealed by tight junction proteins, which control the passage of potentially noxious molecules including proinflammatory cytokines via paracellular pathways. Peripheral nerve barrier breakdown occurs in various neuropathies, such as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and traumatic neuropathy. Here, we studied the functional role of the tight junction protein claudin-12 in regulating peripheral nerve barrier integrity and CIDP pathogenesis. METHODS Sections from sural nerve biopsies from 23 patients with CIDP and non-inflammatory idiopathic polyneuropathy (PNP) were analyzed for claudin-12 and -19 immunoreactivity. Cldn12-KO mice were generated and subjected to the chronic constriction injury (CCI) model of neuropathy. These mice were then characterized using a battery of barrier and behavioral tests, histology, immunohistochemistry, and mRNA/protein expression. In phenotype rescue experiments, the proinflammatory cytokine TNFα was neutralized with the anti-TNFα antibody etanercept; the peripheral nerve barrier was stabilized with the sonic hedgehog agonist smoothened (SAG). RESULTS Compared to those without pain, patients with painful neuropathy exhibited reduced claudin-12 expression independently of fiber loss. Accordingly, global Cldn12-KO in male mice, but not fertile female mice, selectively caused mechanical allodynia associated with a leaky myelin barrier, increased TNFα, decreased sonic hedgehog (SHH), and loss of small axons accompanied by reduced peripheral myelin protein 22 (Pmp22). Other barriers and neurological functions remained intact. The Cldn12-KO phenotype could be rescued either by neutralizing TNFα with etanercept or stabilizing the barrier with SAG, which both also upregulated the Schwann cell barrier proteins Cldn19 and Pmp22. CONCLUSION These results point to a critical role for claudin-12 in maintaining the myelin barrier presumably via Pmp22 and highlight restoration of the hedgehog pathway as a potential treatment strategy for painful inflammatory neuropathy.
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Affiliation(s)
- Jeremy Tsung-Chieh Chen
- University Hospital Würzburg, Center for Interdisciplinary Pain Medicine, Department of Anesthesiology, Intensive Care, Emergency and Pain Medicine, 97080 Würzburg, Germany
| | - Xiawei Hu
- University Hospital Würzburg, Center for Interdisciplinary Pain Medicine, Department of Anesthesiology, Intensive Care, Emergency and Pain Medicine, 97080 Würzburg, Germany
| | - Isabel U C Otto
- University Hospital Würzburg, Center for Interdisciplinary Pain Medicine, Department of Anesthesiology, Intensive Care, Emergency and Pain Medicine, 97080 Würzburg, Germany
| | - Christina Schürger
- University Hospital Würzburg, Center for Interdisciplinary Pain Medicine, Department of Anesthesiology, Intensive Care, Emergency and Pain Medicine, 97080 Würzburg, Germany
| | - Bruno Rogalla von Bieberstein
- University Hospital Würzburg, Center for Interdisciplinary Pain Medicine, Department of Anesthesiology, Intensive Care, Emergency and Pain Medicine, 97080 Würzburg, Germany
| | - Kathrin Doppler
- University Hospital Würzburg, Department of Neurology, 97080 Würzburg, Germany
| | - Susanne M Krug
- Charité-Universitätsmedizin Berlin, Clinical Physiology/Nutritional Medicine, 13125 Berlin, Germany
| | - Mohammed K Hankir
- University Hospital Würzburg, Department of General, Transplantation, Visceral, Vascular and Pediatric Surgery, 97080 Würzburg, Germany
| | - Rosel Blasig
- Leibnitz Institute of Molecular Pharmacology, Departments of Molecular Physiology and Cell Biology, 13125 Berlin, Germany
| | - Claudia Sommer
- University Hospital Würzburg, Department of Neurology, 97080 Würzburg, Germany
| | - Alexander Brack
- University Hospital Würzburg, Center for Interdisciplinary Pain Medicine, Department of Anesthesiology, Intensive Care, Emergency and Pain Medicine, 97080 Würzburg, Germany
| | - Ingolf E Blasig
- Leibnitz Institute of Molecular Pharmacology, Departments of Molecular Physiology and Cell Biology, 13125 Berlin, Germany
| | - Heike L Rittner
- University Hospital Würzburg, Center for Interdisciplinary Pain Medicine, Department of Anesthesiology, Intensive Care, Emergency and Pain Medicine, 97080 Würzburg, Germany.
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14
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Nyimanu D, Behm C, Choudhury S, Yu ASL. The role of claudin-2 in kidney function and dysfunction. Biochem Soc Trans 2023; 51:1437-1445. [PMID: 37387353 DOI: 10.1042/bst20220639] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 06/19/2023] [Accepted: 06/22/2023] [Indexed: 07/01/2023]
Abstract
Claudin-2 is a tight junction protein expressed in leaky epithelia where it forms paracellular pores permeable to cations and water. The paracellular pore formed by claudin-2 is important in energy-efficient cation and water transport in the proximal tubules of the kidneys. Mounting evidence now suggests that claudin-2 may modulate cellular processes often altered in disease, including cellular proliferation. Also, dysregulation of claudin-2 expression has been linked to various diseases, including kidney stone disease and renal cell carcinoma. However, the mechanisms linking altered claudin-2 expression and function to disease are poorly understood and require further investigation. The aim of this review is to discuss the current understanding of the role of claudin-2 in kidney function and dysfunction. We provide a general overview of the claudins and their organization in the tight junction, the expression, and function of claudin-2 in the kidney, and the evolving evidence for its role in kidney disease.
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Affiliation(s)
- Duuamene Nyimanu
- The Jared Grantham Kidney Institute, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, U.S.A
| | - Christine Behm
- The Jared Grantham Kidney Institute, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, U.S.A
| | - Sonali Choudhury
- The Jared Grantham Kidney Institute, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, U.S.A
| | - Alan S L Yu
- The Jared Grantham Kidney Institute, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, U.S.A
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15
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Alexander RT. Kidney stones, hypercalciuria, and recent insights into proximal tubule calcium reabsorption. Curr Opin Nephrol Hypertens 2023; 32:359-365. [PMID: 37074688 DOI: 10.1097/mnh.0000000000000892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
PURPOSE OF REVIEW Most kidney stones are composed of calcium, and the greatest risk factor for kidney stone formation is hypercalciuria. Patients who form kidney stones often have reduced calcium reabsorption from the proximal tubule, and increasing this reabsorption is a goal of some dietary and pharmacological treatment strategies to prevent kidney stone recurrence. However, until recently, little was known about the molecular mechanism that mediates calcium reabsorption from the proximal tubule. This review summarizes newly uncovered key insights and discusses how they may inform the treatment of kidney stone formers. RECENT FINDINGS Studies examining claudin-2 and claudin-12 single and double knockout mice, combined with cell culture models, support complementary independent roles for these tight junction proteins in contributing paracellular calcium permeability to the proximal tubule. Moreover, a family with a coding variation in claudin-2 causing hypercalciuria and kidney stones have been reported, and reanalysis of Genome Wide Association Study (GWAS) data demonstrates an association between noncoding variations in CLDN2 and kidney stone formation. SUMMARY The current work begins to delineate the molecular mechanisms whereby calcium is reabsorbed from the proximal tubule and suggests a role for altered claudin-2 mediated calcium reabsorption in the pathogenesis of hypercalciuria and kidney stone formation.
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Affiliation(s)
- R Todd Alexander
- Department of Pediatrics
- Department of Physiology, University of Alberta
- The Women's & Children's Health Research Institute, Edmonton, Alberta, Canada
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16
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Beggs MR, Young K, Plain A, O'Neill DD, Raza A, Flockerzi V, Dimke H, Alexander RT. Maternal Epidermal Growth Factor Promotes Neonatal Claudin-2 Dependent Increases in Small Intestinal Calcium Permeability. FUNCTION 2023; 4:zqad033. [PMID: 37575484 PMCID: PMC10413934 DOI: 10.1093/function/zqad033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 06/01/2023] [Accepted: 06/12/2023] [Indexed: 08/15/2023] Open
Abstract
A higher concentration of calcium in breast milk than blood favors paracellular calcium absorption enabling growth during postnatal development. We aimed to determine whether suckling animals have greater intestinal calcium permeability to maximize absorption and to identify the underlying molecular mechanism. We examined intestinal claudin expression at different ages in mice and in human intestinal epithelial (Caco-2) cells in response to hormones or human milk. We also measured intestinal calcium permeability in wildtype, Cldn2 and Cldn12 KO mice and Caco-2 cells in response to hormones or human milk. Bone mineralization in mice was assessed by μCT. Calcium permeability across the jejunum and ileum of mice were 2-fold greater at 2 wk than 2 mo postnatal age. At 2 wk, Cldn2 and Cldn12 expression were greater, but only Cldn2 KO mice had decreased calcium permeability compared to wildtype. This translated to decreased bone volume, cross-sectional thickness, and tissue mineral density of femurs. Weaning from breast milk led to a 50% decrease in Cldn2 expression in the jejunum and ileum. Epidermal growth factor (EGF) in breast milk specifically increased only CLDN2 expression and calcium permeability in Caco-2 cells. These data support intestinal permeability to calcium, conferred by claudin-2, being greater in suckling mice and being driven by EGF in breast milk. Loss of the CLDN2 pathway leads to suboptimal bone mineralization at 2 wk of life. Overall, EGF-mediated control of intestinal claudin-2 expression contributes to maximal intestinal calcium absorption in suckling animals.
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Affiliation(s)
- Megan R Beggs
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
- The Women's & Children's Health Research Institute, Edmonton, AB T6G 1C9, Canada
| | - Kennedi Young
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Allen Plain
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Debbie D O'Neill
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Ahsan Raza
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, 66421 Homburg, Germany
| | - Veit Flockerzi
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, 66421 Homburg, Germany
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense C DK-5000, Demark
- Department of Nephrology, Odense University Hospital, 5000 Odense C, Denmark
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
- The Women's & Children's Health Research Institute, Edmonton, AB T6G 1C9, Canada
- Department of Pediatrics, University of Alberta, Edmonton, AB T6G 1C9, Canada
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17
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Alexander RT. Do Thiazides Reduce the Risk of Kidney-Stone Recurrence? N Engl J Med 2023; 388:841-842. [PMID: 36856621 DOI: 10.1056/nejme2300120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Affiliation(s)
- R Todd Alexander
- From the Department of Pediatrics, University of Alberta, Edmonton, Canada
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18
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Houillier P, Lievre L, Hureaux M, Prot-Bertoye C. Mechanisms of paracellular transport of magnesium in intestinal and renal epithelia. Ann N Y Acad Sci 2023; 1521:14-31. [PMID: 36622354 DOI: 10.1111/nyas.14953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Magnesium is the fourth most abundant cation in the body. It plays a critical role in many biological processes, including the process of energy release. Paracellular transport of magnesium is mandatory for magnesium homeostasis. In addition to intestinal absorption that occurs in part across the paracellular pathway, magnesium is reabsorbed by the kidney tubule. The bulk of magnesium is reabsorbed through the paracellular pathway in the proximal tubule and the thick ascending limb of the loop of Henle. The finding that rare genetic diseases due to pathogenic variants in genes encoding specific claudins (CLDNs), proteins located at the tight junction that determine the selectivity and the permeability of the paracellular pathway, led to an awareness of their importance in magnesium homeostasis. Familial hypomagnesemia with hypercalciuria and nephrocalcinosis is caused by a loss of function of CLDN16 or CLDN19. Pathogenic CLDN10 variants cause HELIX syndrome, which is associated with a severe renal loss of sodium chloride and hypermagnesemia. The present review summarizes the current knowledge of the mechanisms and factors involved in paracellular magnesium permeability. The review also highlights some of the unresolved questions that need to be addressed.
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Affiliation(s)
- Pascal Houillier
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université Paris Cité, Paris, France
- CNRS ERL 8228 - Laboratoire de Physiologie Rénale et Tubulopathies, Paris, France
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Physiologie, Paris, France
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France
- Centre de Référence des Maladies Rares du Calcium et du Phosphate, Paris, France
| | - Loïc Lievre
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université Paris Cité, Paris, France
- CNRS ERL 8228 - Laboratoire de Physiologie Rénale et Tubulopathies, Paris, France
| | - Marguerite Hureaux
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Génétique, Paris, France
- Paris Centre de Recherche Cardio-vasculaire, INSERM, Université Paris Cité, Paris, France
| | - Caroline Prot-Bertoye
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université Paris Cité, Paris, France
- CNRS ERL 8228 - Laboratoire de Physiologie Rénale et Tubulopathies, Paris, France
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Physiologie, Paris, France
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France
- Centre de Référence des Maladies Rares du Calcium et du Phosphate, Paris, France
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19
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Kriuchkova N, Breiderhoff T, Müller D, Yilmaz DE, Demirci H, Drewell H, Günzel D, Himmerkus N, Bleich M, Persson PB, Mutig K. Furosemide rescues hypercalciuria in familial hypomagnesaemia with hypercalciuria and nephrocalcinosis model. Acta Physiol (Oxf) 2023; 237:e13927. [PMID: 36606514 DOI: 10.1111/apha.13927] [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: 06/08/2022] [Revised: 11/10/2022] [Accepted: 01/02/2023] [Indexed: 01/07/2023]
Abstract
AIM Perturbed calcium homeostasis limits life expectancy in familial hypomagnesaemia with hypercalciuria and nephrocalcinosis (FHHNC). This rare disease occurs by loss-of-function mutations in CLDN16 or CLDN19 genes, causing impaired paracellular reabsorption of divalent cations along the cortical thick ascending limb (cTAL). Only partial compensation takes place in the ensuing late distal convoluted tubule, connecting tubule, and collecting duct, where the luminal transient receptor potential channel V5 (TRPV5), as well as basolateral plasma membrane calcium ATPase (PMCA) and sodium-potassium exchanger (NCX1) mediate transcellular Ca2+ reabsorption. The loop diuretic furosemide induces compensatory activation in these distal segments. Normally, furosemide enhances urinary calcium excretion via inhibition of the aforementioned cTAL. As Ca2+ reabsorption in the cTAL is already severely impaired in FHHNC patients, furosemide may alleviate hypercalciuria in this disease by activation of the distal transcellular Ca2+ transport proteins. METHODS Cldn16-deficient mice (Cldn16-/- ) served as a FHHNC model. Wild-type (WT) and Cldn16-/- mice were treated with furosemide (7 days of 40 mg/kg bw) or vehicle. We assessed renal electrolyte handling (metabolic cages) and key divalent transport proteins. RESULTS Cldn16-/- mice show higher Ca2+ excretion than WT and compensatory stimulation of Cldn2, TRPV5, and NCX1 at baseline. Furosemide reduced hypercalciuria in Cldn16-/- mice and enhanced TRPV5 and PMCA levels in Cldn16-/- but not in WT mice. CONCLUSIONS Furosemide significantly reduces hypercalciuria, likely via upregulation of luminal and basolateral Ca2+ transport systems in the distal nephron and collecting duct in this model for FHHNC.
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Affiliation(s)
- Natalia Kriuchkova
- Department of Translational Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Tilman Breiderhoff
- Division of Gastroenterology, Nephrology and Metabolic Diseases, Department of Pediatrics, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Dominik Müller
- Division of Gastroenterology, Nephrology and Metabolic Diseases, Department of Pediatrics, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Duygu Elif Yilmaz
- Department of Functional Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Hasan Demirci
- Department of Functional Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Hoora Drewell
- Department of Translational Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Dorothee Günzel
- Clinical Physiology/Division of Nutritional Medicine, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | | | - Markus Bleich
- Institute of Physiology, Kiel University, Kiel, Germany
| | - Pontus B Persson
- Department of Translational Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Kerim Mutig
- Department of Translational Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
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20
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Abstract
Mg2+ is essential for many cellular and physiological processes, including muscle contraction, neuronal activity, and metabolism. Consequently, the blood Mg2+ concentration is tightly regulated by balanced intestinal Mg2+ absorption, renal Mg2+ excretion, and Mg2+ storage in bone and soft tissues. In recent years, the development of novel transgenic animal models and identification of Mendelian disorders has advanced our current insight in the molecular mechanisms of Mg2+ reabsorption in the kidney. In the proximal tubule, Mg2+ reabsorption is dependent on paracellular permeability by claudin-2/12. In the thick ascending limb of Henle's loop, the claudin-16/19 complex provides a cation-selective pore for paracellular Mg2+ reabsorption. The paracellular Mg2+ reabsorption in this segment is regulated by the Ca2+-sensing receptor, parathyroid hormone, and mechanistic target of rapamycin (mTOR) signaling. In the distal convoluted tubule, the fine tuning of Mg2+ reabsorption takes place by transcellular Mg2+ reabsorption via transient receptor potential melastatin-like types 6 and 7 (TRPM6/TRPM7) divalent cation channels. Activity of TRPM6/TRPM7 is dependent on hormonal regulation, metabolic activity, and interacting proteins. Basolateral Mg2+ extrusion is still poorly understood but is probably dependent on the Na+ gradient. Cyclin M2 and SLC41A3 are the main candidates to act as Na+/Mg2+ exchangers. Consequently, disturbances of basolateral Na+/K+ transport indirectly result in impaired renal Mg2+ reabsorption in the distal convoluted tubule. Altogether, this review aims to provide an overview of the molecular mechanisms of Mg2+ reabsorption in the kidney, specifically focusing on transgenic mouse models and human hereditary diseases.
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Affiliation(s)
- Jeroen H F de Baaij
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
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21
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Expression of phosphate and calcium transporters and their regulators in parotid glands of mice. Pflugers Arch 2023; 475:203-216. [PMID: 36274099 PMCID: PMC9849193 DOI: 10.1007/s00424-022-02764-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 10/07/2022] [Accepted: 10/13/2022] [Indexed: 02/01/2023]
Abstract
The concentration of inorganic phosphate (Pi) in plasma is under hormonal control, with deviations from normal values promptly corrected to avoid hyper- or hypophosphatemia. Major regulators include parathyroid hormone (PTH), fibroblast growth factor 23 (FGF-23), and active vitamin D3 (calcitriol). This control is achieved by mechanisms largely dependent on regulating intestinal absorption and renal excretion, whose combined actions stabilise plasma Pi levels at around 1-2 mM. Instead, Pi concentrations up to 13 and 40 mM have been measured in saliva from humans and ruminants, respectively, suggesting that salivary glands have the capacity to concentrate Pi. Here we analysed the transcriptome of parotid glands, ileum, and kidneys of mice, to investigate their potential differences regarding the expression of genes responsible for epithelial transport of Pi as well as their known regulators. Given that Pi and Ca2+ homeostasis are tightly connected, the expression of genes involved in Ca2+ homeostasis was also included. In addition, we studied the effect of vitamin D3 treatment on the expression of Pi and Ca2+ regulating genes in the three major salivary glands. We found that parotid glands are equipped preferentially with Slc20 rather than with Slc34 Na+/Pi cotransporters, are suited to transport Ca2+ through the transcellular and paracellular route and are potential targets for PTH and vitamin D3 regulation.
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22
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Alexander RT, Dimke H. Molecular mechanisms underlying paracellular calcium and magnesium reabsorption in the proximal tubule and thick ascending limb. Ann N Y Acad Sci 2022; 1518:69-83. [PMID: 36200584 DOI: 10.1111/nyas.14909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Calcium and magnesium are the most abundant divalent cations in the body. The plasma level is controlled by coordinated interaction between intestinal absorption, reabsorption in the kidney, and, for calcium at least, bone storage and exchange. The kidney adjusts urinary excretion of these ions in response to alterations in their systemic concentration. Free ionized and anion-complexed calcium and magnesium are filtered at the glomerulus. The majority (i.e., >85%) of filtered divalent cations are reabsorbed via paracellular pathways from the proximal tubule and thick ascending limb (TAL) of the loop of Henle. Interestingly, the largest fraction of filtered calcium is reabsorbed from the proximal tubule (65%), while the largest fraction of filtered magnesium is reclaimed from the TAL (60%). The paracellular pathways mediating these fluxes are composed of tight junctional pores formed by claudins. In the proximal tubule, claudin-2 and claudin-12 confer calcium permeability, while the exact identity of the magnesium pore remains to be determined. Claudin-16 and claudin-19 contribute to the calcium and magnesium permeable pathway in the TAL. In this review, we discuss the data supporting these conclusions and speculate as to why there is greater fractional calcium reabsorption from the proximal tubule and greater fractional magnesium reabsorption from the TAL.
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Affiliation(s)
- R Todd Alexander
- Departments of Physiology & Pediatrics, University of Alberta, Edmonton, Alberta, Canada.,Women's and Children's Health Institute, Edmonton, Alberta, Canada
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Demark.,Department of Nephrology, Odense University Hospital, Odense, Denmark
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23
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Redox and Metabolic Regulation of Intestinal Barrier Function and Associated Disorders. Int J Mol Sci 2022; 23:ijms232214463. [PMID: 36430939 PMCID: PMC9699094 DOI: 10.3390/ijms232214463] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 11/11/2022] [Accepted: 11/14/2022] [Indexed: 11/23/2022] Open
Abstract
The intestinal epithelium forms a physical barrier assembled by intercellular junctions, preventing luminal pathogens and toxins from crossing it. The integrity of tight junctions is critical for maintaining intestinal health as the breakdown of tight junction proteins leads to various disorders. Redox reactions are closely associated with energy metabolism. Understanding the regulation of tight junctions by cellular metabolism and redox status in cells may lead to the identification of potential targets for therapeutic interventions. In vitro and in vivo models have been utilized in investigating intestinal barrier dysfunction and in particular the free-living soil nematode, Caenorhabditis elegans, may be an important alternative to mammalian models because of its convenience of culture, transparent body for microscopy, short generation time, invariant cell lineage and tractable genetics.
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24
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Gonschior H, Schmied C, Van der Veen RE, Eichhorst J, Himmerkus N, Piontek J, Günzel D, Bleich M, Furuse M, Haucke V, Lehmann M. Nanoscale segregation of channel and barrier claudins enables paracellular ion flux. Nat Commun 2022; 13:4985. [PMID: 36008380 PMCID: PMC9411157 DOI: 10.1038/s41467-022-32533-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 08/04/2022] [Indexed: 11/09/2022] Open
Abstract
The paracellular passage of ions and small molecules across epithelia is controlled by tight junctions, complex meshworks of claudin polymers that form tight seals between neighboring cells. How the nanoscale architecture of tight junction meshworks enables paracellular passage of specific ions or small molecules without compromising barrier function is unknown. Here we combine super-resolution stimulated emission depletion microscopy in live and fixed cells and tissues, multivariate classification of super-resolution images and fluorescence resonance energy transfer to reveal the nanoscale organization of tight junctions formed by mammalian claudins. We show that only a subset of claudins can assemble into characteristic homotypic meshworks, whereas tight junctions formed by multiple claudins display nanoscale organization principles of intermixing, integration, induction, segregation, and exclusion of strand assemblies. Interestingly, channel-forming claudins are spatially segregated from barrier-forming claudins via determinants mainly encoded in their extracellular domains also known to harbor mutations leading to human diseases. Electrophysiological analysis of claudins in epithelial cells suggests that nanoscale segregation of distinct channel-forming claudins enables barrier function combined with specific paracellular ion flux across tight junctions. Meshworks of claudin polymers control the paracellular transport and barrier properties of epithelial tight junctions. Here, the authors show different claudin nanoscale organization principles, finding that claudin segregation enables barrier formation and paracellular ion flux across tight junctions.
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Affiliation(s)
- Hannes Gonschior
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125, Berlin, Germany
| | - Christopher Schmied
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125, Berlin, Germany
| | | | - Jenny Eichhorst
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125, Berlin, Germany
| | - Nina Himmerkus
- Institute of Physiology, Christian-Albrechts-Universität zu Kiel, 24118, Kiel, Germany
| | - Jörg Piontek
- Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology, Rheumatology, Charité - Universitätsmedizin Berlin, 12203, Berlin, Germany
| | - Dorothee Günzel
- Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology, Rheumatology, Charité - Universitätsmedizin Berlin, 12203, Berlin, Germany
| | - Markus Bleich
- Institute of Physiology, Christian-Albrechts-Universität zu Kiel, 24118, Kiel, Germany
| | - Mikio Furuse
- Division of Cell Structure, National Institute for Physiological Sciences, Okazaki, Aichi, 444-8787, Japan.,Department of Physiological Sciences, School of Life Science, SOKENDAI (Graduate University for Advanced Studies), Okazaki, Aichi, 444-8585, Japan
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125, Berlin, Germany.,Faculty of Biology, Chemistry and Pharmacy, Freie Universität Berlin, 14195, Berlin, Germany
| | - Martin Lehmann
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125, Berlin, Germany.
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Vitamin D-Mediated Regulation of Intestinal Calcium Absorption. Nutrients 2022; 14:nu14163351. [PMID: 36014856 PMCID: PMC9416674 DOI: 10.3390/nu14163351] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/09/2022] [Accepted: 08/10/2022] [Indexed: 11/27/2022] Open
Abstract
Vitamin D is a critical regulator of calcium and bone homeostasis. While vitamin D has multiple effects on bone and calcium metabolism, the regulation of intestinal calcium (Ca) absorption efficiency is a critical function for vitamin D. This is necessary for optimal bone mineralization during growth, the protection of bone in adults, and the prevention of osteoporosis. Intestinal Ca absorption is regulated by 1,25 dihydroxyvitamin D (1,25(OH)2 D), a hormone that activates gene transcription following binding to the intestinal vitamin D receptor (VDR). When dietary Ca intake is low, Ca absorption follows a vitamin-D-regulated, saturable pathway, but when dietary Ca intake is high, Ca absorption is predominately through a paracellular diffusion pathway. Deletion of genes that mediate vitamin D action (i.e., VDR) or production (CYP27B1) eliminates basal Ca absorption and prevents the adaptation of mice to low-Ca diets. Various physiologic or disease states modify vitamin-D-regulated intestinal absorption of Ca (enhanced during late pregnancy, reduced due to menopause and aging).
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26
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McDonough AA, Fenton RA. Potassium homeostasis: sensors, mediators, and targets. Pflugers Arch 2022; 474:853-867. [PMID: 35727363 PMCID: PMC10163916 DOI: 10.1007/s00424-022-02718-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 06/08/2022] [Accepted: 06/12/2022] [Indexed: 12/16/2022]
Abstract
Transmembrane potassium (K) gradients are key determinants of membrane potential that can modulate action potentials, control muscle contractility, and influence ion channel and transporter activity. Daily K intake is normally equal to the amount of K in the entire extracellular fluid (ECF) creating a critical challenge - how to maintain ECF [K] and membrane potential in a narrow range during feast and famine. Adaptations to maintain ECF [K] include sensing the K intake, sensing ECF [K] vs. desired set-point and activating mediators that regulate K distribution between ECF and ICF, and regulate renal K excretion. In this focused review, we discuss the basis of these adaptions, including (1) potential mechanisms for rapid feedforward signaling to kidney and muscle after a meal (before a rise in ECF [K]), (2) how skeletal muscles sense and respond to changes in ECF [K], (3) effects of K on aldosterone biosynthesis, and (4) how the kidney responds to changes in ECF [K] to modify K excretion. The concepts of sexual dimorphisms in renal K handling adaptation are introduced, and the molecular mechanisms that can account for the benefits of a K-rich diet to maintain cardiovascular health are discussed. Although the big picture of K homeostasis is becoming more clear, we also highlight significant pieces of the puzzle that remain to be solved, including knowledge gaps in our understanding of initiating signals, sensors and their connection to homeostatic adjustments of ECF [K].
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Affiliation(s)
- Alicia A McDonough
- Department of Physiology and Neuroscience, University of Southern California Keck School of Medicine, Los Angeles, CA, USA.
| | - Robert A Fenton
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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27
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Role of Autophagy Inducers and Inhibitors in Intestinal Barrier Injury Induced by Intestinal Ischemia–Reperfusion (I/R). J Immunol Res 2022; 2022:9822157. [PMID: 35942211 PMCID: PMC9356893 DOI: 10.1155/2022/9822157] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 07/05/2022] [Accepted: 07/07/2022] [Indexed: 11/17/2022] Open
Abstract
Objectives Intestinal epithelial barrier function is an important mechanical barrier to maintain intestinal homeostasis and resist the invasion of intestinal pathogens and microorganisms. However, intestinal epithelial barrier function is vulnerable to damage under intestinal ischemia–reperfusion (I/R) injury. Under a category of pathophysiological conditions, including I/R, autophagy plays a crucial role. This study is aimed at discussing the role of autophagy inhibitors and activators in intestinal epithelial barrier function after intestinal I/R by changing autophagy levels. Methods Mice with intestinal IR underwent 45 minutes of surgery for superior mesenteric artery occlusion. The autophagy inhibitor 3-MA and the autophagy inducer rapamycin (RAP) were used to change the level of autophagy, and then, the expressions of tight junction proteins and intestinal barrier function were detected. Results The results showed that the autophagy inhibitor 3-MA aggravated intestinal epithelial barrier dysfunction, while the autophagy inducer RAP attenuated intestinal epithelial barrier dysfunction. In addition, promoting autophagy may promote occludin expression by inhibiting claudin-2 expression. Conclusion Upregulation of autophagy levels by autophagy inducers can enhance intestinal epithelial barrier function after intestinal I/R.
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28
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The importance of kidney calcium handling in the homeostasis of extracellular fluid calcium. Pflugers Arch 2022; 474:885-900. [PMID: 35842482 DOI: 10.1007/s00424-022-02725-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 06/09/2022] [Accepted: 06/30/2022] [Indexed: 12/13/2022]
Abstract
Extracellular fluid calcium concentration must be maintained within a narrow range in order to sustain many biological functions, encompassing muscle contraction, blood coagulation, and bone and tooth mineralization. Blood calcium value is critically dependent on the ability of the renal tubule to reabsorb the adequate amount of filtered calcium. Tubular calcium reabsorption is carried out by various and complex mechanisms in 3 distinct segments: the proximal tubule, the cortical thick ascending limb of the loop of Henle, and the late distal convoluted/connecting tubule. In addition, calcium reabsorption is tightly controlled by many endocrine, paracrine, and autocrine factors, as well as by non-hormonal factors, in order to adapt the tubular handling of calcium to the metabolic requirements. The present review summarizes the current knowledge of the mechanisms and factors involved in calcium handling by the kidney and, ultimately, in extracellular calcium homeostasis. The review also highlights some of our gaps in understanding that need to be addressed in the future.
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29
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Young K, Beggs MR, Grimbly C, Alexander RT. Regulation of 1 and 24 hydroxylation of vitamin D metabolites in the proximal tubule. Exp Biol Med (Maywood) 2022; 247:1103-1111. [PMID: 35482362 PMCID: PMC9335508 DOI: 10.1177/15353702221091982] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Calcium and phosphate are critical for numerous physiological processes. Consequently, the plasma concentration of these ions are tightly regulated. Calcitriol, the active form of vitamin D, is a positive modulator of mineralization as well as calcium and phosphate metabolism. The molecular and physiological effects of calcitriol are well documented. Calcitriol increases blood calcium and phosphate levels by increasing absorption from the intestine, and resorption of bone. Calcitriol synthesis is a multistep process. A precursor is first made via skin exposure to UV, it is then 25-hydroxylated in the liver to form 25-hydroxyitamin D. The next hydroxylation step occurs in the renal proximal tubule via the 1-αhydroxylase enzyme (encoded by CYP27B1) thereby generating 1,25-dihydroxyvitamin D, that is, calcitriol. At the same site, the 25-hydroxyvitamin D 24-hydroxlase enzyme encoded by CYP24A1 can hydroxylate 25-hydroxyvitamin D or calcitriol to deactivate the hormone. Plasma calcitriol levels are primarily determined by the regulated expression of CYP27B1 and CYP24A1. This occurs in response to parathyroid hormone (increases CYP27B1), calcitriol itself (decreases CYP27B1 and increases CYP24A1), calcitonin (increases or decreases CYP24A1 and increases CYP27B1), FGF23 (decreases CYP27B1 and increases CYP24A1) and potentially plasma calcium and phosphate levels themselves (mixed effects). Herein, we review the regulation of CYP27B1 and CYP24A1 transcription in response to the action of classic phophocalciotropic hormones and explore the possibility of direct regulation by plasma calcium.
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Affiliation(s)
- Kennedi Young
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada,Women and Children’s Health Institute, Edmonton, AB T6G 1C9, Canada
| | - Megan R Beggs
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada,Women and Children’s Health Institute, Edmonton, AB T6G 1C9, Canada
| | - Chelsey Grimbly
- Department of Paediatrics, University of Alberta, Edmonton, AB T6G 1C9, Canada
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada,Women and Children’s Health Institute, Edmonton, AB T6G 1C9, Canada,Department of Paediatrics, University of Alberta, Edmonton, AB T6G 1C9, Canada,R Todd Alexander.
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30
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Beggs MR, Bhullar H, Dimke H, Alexander RT. The contribution of regulated colonic calcium absorption to the maintenance of calcium homeostasis. J Steroid Biochem Mol Biol 2022; 220:106098. [PMID: 35339651 DOI: 10.1016/j.jsbmb.2022.106098] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/05/2022] [Accepted: 03/20/2022] [Indexed: 11/20/2022]
Abstract
Calcium absorption and secretion can occur along the length of the small and large intestine. To date, the focus of research into intestinal calcium absorption has been the small intestine, the site contributing the majority of intestinal calcium absorption. However, evidence that the colon contributes as much as 10% of enteral calcium transport has been available for decades. Transcellular calcium absorption and bidirectional paracellular calcium flux contributing to either net absorption or secretion have been observed in the colon, depending on the physiological state. Moreover, the calcium transport pathways contributing to colonic absorption or secretion are regulated by a variety of hormones, including calcitriol, plasma calcium and dietary factors, including prebiotics. Herein we review historical and recent research highlighting the role of colonic calcium transport in overall maintenance of calcium balance, and suggest these data are consistent with the colon being a site of significant regulated transepithelial calcium transport.
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Affiliation(s)
- Megan R Beggs
- Department of Physiology, University of Alberta, Canada; Women's and Children's Health Institute, Alberta, Canada
| | | | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Demark; Department of Nephrology, Odense University Hospital, Denmark
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Canada; Women's and Children's Health Institute, Alberta, Canada; Department of Paediatrics, University of Alberta, Canada.
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31
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Xing W, Pourteymoor S, Chen Y, Mohan S. Targeted Deletion of the Claudin12 Gene in Mice Increases Articular Cartilage and Inhibits Chondrocyte Differentiation. Front Endocrinol (Lausanne) 2022; 13:931318. [PMID: 35937800 PMCID: PMC9354527 DOI: 10.3389/fendo.2022.931318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 06/22/2022] [Indexed: 11/27/2022] Open
Abstract
To study the role of Claudin (CLDN)12 in bone, we developed mice with a targeted deletion of exon2 in the Cldn12 gene for skeletal phenotype analysis. Micro-CT analysis of the secondary spongiosa of distal femurs of mice with targeted disruption of the Cldn12 gene and control littermates showed no significant genotype-specific differences in either cortical or trabecular bone parameters for either gender in 13-week-old mice. Immunohistochemistry revealed that while CLDN12 was expressed in both differentiating chondrocytes and osteoblasts of the secondary spongiosa of 3-week-old wild-type mice, its expression was restricted to differentiating chondrocytes in the articular cartilage and growth plate in adult mice. Articular cartilage area at the knee were increased by 47% in Cldn12 knockout (KO) mice compared to control littermates. Micro-CT analyses found that while the trabecular number was increased by 9% and the trabecular spacing was reduced by 9% in the femoral epiphysis of Cldn12 KO mice, neither bone volume nor bone volume adjusted for tissue volume was different between the two genotypes. The expression levels of Clusterin, Lubricin and Mmp13 were increased by 56%, 46%, and 129%, respectively, in primary articular chondrocytes derived from KO compared to control mice. Our data indicate that targeted deletion of the Cldn12 gene in mice increases articular cartilage, in part, by promoting articular chondrocyte phenotype.
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Affiliation(s)
- Weirong Xing
- Musculoskeletal Disease Center, VA Loma Linda Healthcare Systems, Loma Linda, CA, United States
- Department of Medicine, Loma Linda University, Loma Linda, CA, United States
| | - Sheila Pourteymoor
- Musculoskeletal Disease Center, VA Loma Linda Healthcare Systems, Loma Linda, CA, United States
| | - Yian Chen
- Musculoskeletal Disease Center, VA Loma Linda Healthcare Systems, Loma Linda, CA, United States
| | - Subburaman Mohan
- Musculoskeletal Disease Center, VA Loma Linda Healthcare Systems, Loma Linda, CA, United States
- Department of Medicine, Loma Linda University, Loma Linda, CA, United States
- Department of Biochemistry, Loma Linda University, Loma Linda, CA, United States
- Department of Orthopedic Surgery, Loma Linda University, Loma Linda, CA, United States
- *Correspondence: Subburaman Mohan,
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