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Adella A, Gommers LMM, Bos C, Leermakers PA, de Baaij JHF, Hoenderop JGJ. Characterization of intestine-specific TRPM6 knockout C57BL/6 J mice: effects of short-term omeprazole treatment. Pflugers Arch 2024:10.1007/s00424-024-03017-9. [PMID: 39266724 DOI: 10.1007/s00424-024-03017-9] [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: 03/22/2024] [Revised: 09/04/2024] [Accepted: 09/05/2024] [Indexed: 09/14/2024]
Abstract
The transient receptor potential melastatin type 6 (TRPM6) is a divalent cation channel pivotal for gatekeeping Mg2+ balance. Disturbance in Mg2+ balance has been associated with the chronic use of proton pump inhibitors (PPIs) such as omeprazole. In this study, we investigated if TRPM6 plays a role in mediating the effects of short-term (4 days) omeprazole treatment on intestinal Mg2+ malabsorption using intestine-specific TRPM6 knockout (Vill1-TRPM6-/-) mice. To do this, forty-eight adult male C57BL/6 J mice (50% TRPM6fl/fl and 50% Vill1-TRPM6-/-) were characterized, and the distal colon of these mice was subjected to RNA sequencing. Moreover, these mice were exposed to 20 mg/kg bodyweight omeprazole or placebo for 4 days. Vill1-TRPM6-/- mice had a significantly lower 25Mg2+ absorption compared to control TRPM6fl/fl mice, accompanied by lower Mg2+ serum levels, and urinary Mg2+ excretion. Furthermore, renal Slc41a3, Trpm6, and Trpm7 gene expressions were higher in these animals, indicating a compensatory mechanism via the kidney. RNA sequencing of the distal colon revealed a downregulation of the Mn2+ transporter Slc30a10. However, no changes in Mn2+ serum, urine, and feces levels were observed. Moreover, 4 days omeprazole treatment did not affect Mg2+ homeostasis as no changes in serum 25Mg2+ and total Mg2+ were seen. In conclusion, we demonstrate here for the first time that Vill1-TRPM6-/- mice have a lower Mg2+ absorption in the intestines. Moreover, short-term omeprazole treatment does not alter Mg2+ absorption in both Vill1-TRPM6-/- and TRPM6fl/fl mice. This suggests that TRPM6-mediated Mg2+ absorption in the intestines is not affected by short-term PPI administration.
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Affiliation(s)
- Anastasia Adella
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Lisanne M M Gommers
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Caro Bos
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Pieter A Leermakers
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jeroen H F de Baaij
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joost G J Hoenderop
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands.
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Nie M, Zhang J, Bal M, Duran C, An SW, Zigman JM, Baum M, Hiremath C, Marciano DK, Wolf MTF. Ghrelin enhances tubular magnesium absorption in the kidney. Front Physiol 2024; 15:1363708. [PMID: 38638279 PMCID: PMC11024433 DOI: 10.3389/fphys.2024.1363708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Accepted: 03/07/2024] [Indexed: 04/20/2024] Open
Abstract
Osteoporosis after bariatric surgery is an increasing health concern as the rate of bariatric surgery has risen. In animal studies mimicking bariatric procedures, bone disease, together with decreased serum levels of Ca2+, Mg2+ and the gastric hormone Ghrelin were described. Ghrelin regulates metabolism by binding to and activating the growth hormone secretagogue receptor (GHSR) which is also expressed in the kidney. As calcium and magnesium are key components of bone, we tested the hypothesis that Ghrelin-deficiency contributes to osteoporosis via reduced upregulation of the renal calcium channel TRPV5 and the heteromeric magnesium channel TRPM6/7. We expressed GHSR with TRPV5 or TRPM6/7 channel in HEK293 cells and treated them with purified Ghrelin. Whole-cell current density was analyzed by patch-clamp recording. Nephron-specific gene expression was performed by tubular microdissection followed by qPCR in wild-type (WT) mice, and immunofluorescent imaging of GHSR-eGFP mice. Tubular magnesium homeostasis was analyzed in GHSR-null and WT mice at baseline and after caloric restriction. After Ghrelin exposure, whole-cell current density did not change for TRPV5 but increased for TRPM6/7 in a dose-dependent fashion. Applying the Ghrelin-mimetic (D-Trp7, Ala8,D-Phe10)-α-MSH (6-11) amide without and with the GHSR antagonist (D-Lys3)-GHRP6, we confirmed the stimulatory role of Ghrelin towards TRPM6/7. As GHSR initiates downstream signaling via protein kinase A (PKA), we found that the PKA inhibitor H89 abrogated TRPM6/7 stimulation by Ghrelin. Similarly, transfected Gαs, but not the Gαs mutant Q227L, nor Gαi2, Gαq, or Gα13 upregulated TRPM6/7 current density. In microdissected TALs and DCTs similar levels of GHSR mRNA were detected. In contrast, TRPM6 mRNA was expressed in the DCT and also detected in the TAL at 25% expression compared to DCT. Immunofluorescent studies using reporter GHSR-eGFP mice showed a strong eGFP signal in the TAL but surprisingly displayed no eGFP signal in the DCT. In 3-, 6-, and 9-month-old GHSR-null and WT mice, baseline serum magnesium was not significantly different, but 24-h urinary magnesium excretion was elevated in 9-month-old GHSR-null mice. In calorically restricted GHSR-null mice, we detected excess urinary magnesium excretion and reduced serum magnesium levels compared to WT mice. The kidneys from calorically restricted WT mice showed upregulated gene expression of magnesiotropic genes Hnf1b, Cldn-16, Cldn-19, Fxyd-2b, and Parvalbumin compared to GHSR-null mice. Our in vitro studies show that Ghrelin stimulates TRPM6/7 via GHSR and Gαs-PKA signaling. The murine studies are consistent with Ghrelin-GHSR signaling inducing reduced urinary magnesium excretion, particularly in calorically restricted mice when Ghrelin levels are elevated. This effect may be mediated by Ghrelin-upregulation of TRPM6 in the TAL and/or upregulation of other magnesiotropic genes. We postulate that rising Ghrelin levels with hunger contribute to increased renal Mg2+ reabsorption to compensate for lack of enteral Mg2+ uptake.
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Affiliation(s)
- Mingzhu Nie
- Pediatric Nephrology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Jing Zhang
- Pediatric Nephrology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Manjot Bal
- Pediatric Nephrology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Claudia Duran
- Pediatric Nephrology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Sung Wan An
- Pediatric Nephrology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, United States
- Pediatric Nephrology, Department of Pediatrics, University of Michigan, Ann Arbor, MI, United States
| | - Jeffrey M. Zigman
- Department of Internal Medicine, Center for Hypothalamic Research, UTSW Medical Center, Dallas, TX, United States
| | - Michel Baum
- Pediatric Nephrology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Chitkale Hiremath
- Department of Internal Medicine, Nephrology, and Department of Cell Biology, UTSW Medical Center, Dallas, TX, United States
| | - Denise K. Marciano
- Department of Internal Medicine, Nephrology, and Department of Cell Biology, UTSW Medical Center, Dallas, TX, United States
| | - Matthias T. F. Wolf
- Pediatric Nephrology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, United States
- Pediatric Nephrology, Department of Pediatrics, University of Michigan, Ann Arbor, MI, United States
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3
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Chubanov V, Köttgen M, Touyz RM, Gudermann T. TRPM channels in health and disease. Nat Rev Nephrol 2024; 20:175-187. [PMID: 37853091 DOI: 10.1038/s41581-023-00777-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/25/2023] [Indexed: 10/20/2023]
Abstract
Different cell channels and transporters tightly regulate cytoplasmic levels and the intraorganelle distribution of cations. Perturbations in these processes lead to human diseases that are frequently associated with kidney impairment. The family of melastatin-related transient receptor potential (TRPM) channels, which has eight members in mammals (TRPM1-TRPM8), includes ion channels that are highly permeable to divalent cations, such as Ca2+, Mg2+ and Zn2+ (TRPM1, TRPM3, TRPM6 and TRPM7), non-selective cation channels (TRPM2 and TRPM8) and monovalent cation-selective channels (TRPM4 and TRPM5). Three family members contain an enzymatic protein moiety: TRPM6 and TRPM7 are fused to α-kinase domains, whereas TRPM2 is linked to an ADP-ribose-binding NUDT9 homology domain. TRPM channels also function as crucial cellular sensors involved in many physiological processes, including mineral homeostasis, blood pressure, cardiac rhythm and immunity, as well as photoreception, taste reception and thermoreception. TRPM channels are abundantly expressed in the kidney. Mutations in TRPM genes cause several inherited human diseases, and preclinical studies in animal models of human disease have highlighted TRPM channels as promising new therapeutic targets. Here, we provide an overview of this rapidly evolving research area and delineate the emerging role of TRPM channels in kidney pathophysiology.
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Affiliation(s)
- Vladimir Chubanov
- Walther-Straub Institute of Pharmacology and Toxicology, LMU Munich, Munich, Germany.
| | - Michael Köttgen
- Renal Division, Department of Medicine, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- CIBSS - Centre for Integrative Biological Signalling Studies, Freiburg, Germany
| | - Rhian M Touyz
- Research Institute of McGill University Health Centre, McGill University, Montreal, Quebec, Canada
| | - Thomas Gudermann
- Walther-Straub Institute of Pharmacology and Toxicology, LMU Munich, Munich, Germany.
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Gelineau-van Waes J, van Waes MA, Hallgren J, Hulen J, Bredehoeft M, Ashley-Koch AE, Krupp D, Gregory SG, Stessman HA. Gene-nutrient interactions that impact magnesium homeostasis increase risk for neural tube defects in mice exposed to dolutegravir. Front Cell Dev Biol 2023; 11:1175917. [PMID: 37377737 PMCID: PMC10292217 DOI: 10.3389/fcell.2023.1175917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 05/19/2023] [Indexed: 06/29/2023] Open
Abstract
In 2018, data from a surveillance study in Botswana evaluating adverse birth outcomes raised concerns that women on antiretroviral therapy (ART) containing dolutegravir (DTG) may be at increased risk for neural tube defects (NTDs). The mechanism of action for DTG involves chelation of Mg2+ ions in the active site of the viral integrase. Plasma Mg2+ homeostasis is maintained primarily through dietary intake and reabsorption in the kidneys. Inadequate dietary Mg2+ intake over several months results in slow depletion of plasma Mg2+ and chronic latent hypomagnesemia, a condition prevalent in women of reproductive age worldwide. Mg2+ is critical for normal embryonic development and neural tube closure. We hypothesized that DTG therapy might slowly deplete plasma Mg2+ and reduce the amount available to the embryo, and that mice with pre-existing hypomagnesemia due to genetic variation and/or dietary Mg2+ insufficiency at the time of conception and initiation of DTG treatment would be at increased risk for NTDs. We used two different approaches to test our hypothesis: 1) we selected mouse strains that had inherently different basal plasma Mg2+ levels and 2) placed mice on diets with different concentrations of Mg2+. Plasma and urine Mg2+ were determined prior to timed mating. Pregnant mice were treated daily with vehicle or DTG beginning on the day of conception and embryos examined for NTDs on gestational day 9.5. Plasma DTG was measured for pharmacokinetic analysis. Our results demonstrate that hypomagnesemia prior to conception, due to genetic variation and/or insufficient dietary Mg2+ intake, increases the risk for NTDs in mice exposed to DTG. We also analyzed whole-exome sequencing data from inbred mouse strains and identified 9 predicted deleterious missense variants in Fam111a that were unique to the LM/Bc strain. Human FAM111A variants are associated with hypomagnesemia and renal Mg2+ wasting. The LM/Bc strain exhibits this same phenotype and was the strain most susceptible to DTG-NTDs. Our results suggest that monitoring plasma Mg2+ levels in patients on ART regimens that include DTG, identifying other risk factors that impact Mg2+ homeostasis, and correcting deficiencies in this micronutrient might provide an effective strategy for mitigating NTD risk.
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Affiliation(s)
- J. Gelineau-van Waes
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE, United States
| | | | - J. Hallgren
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE, United States
| | - J. Hulen
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE, United States
| | - M. Bredehoeft
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE, United States
| | - A. E. Ashley-Koch
- Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC, United States
| | - D. Krupp
- Department of Medicine, Duke University Medical Center, Durham, NC, United States
| | - S. G. Gregory
- Department of Neurosurgery, Duke University Medical Center, Durham, NC, United States
| | - H. A. Stessman
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE, United States
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5
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Ray E, Mohan K, Ahmad S, Wolf MTF. Physiology of a Forgotten Electrolyte-Magnesium Disorders. ADVANCES IN KIDNEY DISEASE AND HEALTH 2023; 30:148-163. [PMID: 36868730 DOI: 10.1053/j.akdh.2022.12.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Revised: 11/26/2022] [Accepted: 12/06/2022] [Indexed: 03/05/2023]
Abstract
Magnesium (Mg2+) is the second most common intracellular cation and the fourth most abundant element on earth. However, Mg2+ is a frequently overlooked electrolyte and often not measured in patients. While hypomagnesemia is common in 15% of the general population, hypermagnesemia is typically only found in preeclamptic women after Mg2+ therapy and in patients with ESRD. Mild to moderate hypomagnesemia has been associated with hypertension, metabolic syndrome, type 2 diabetes mellitus, CKD, and cancer. Nutritional Mg2+ intake and enteral Mg2+ absorption are important for Mg2+ homeostasis, but the kidneys are the key regulators of Mg2+ homeostasis by limiting urinary excretion to less than 4% while the gastrointestinal tract loses over 50% of the Mg2+ intake in the feces. Here, we review the physiological relevance of Mg2+, the current knowledge of Mg2+ absorption in the kidneys and the gut, the different causes of hypomagnesemia, and a diagnostic approach on how to assess Mg2+ status. We highlight the latest discoveries of monogenetic conditions causing hypomagnesemia, which have enhanced our understanding of tubular Mg2+ absorption. We will also discuss external and iatrogenic causes of hypomagnesemia and advances in the treatment of hypomagnesemia.
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Affiliation(s)
- Evan Ray
- Renal-Electrolyte Division, Department of Internal Medicine, University of Pittsburgh, PA
| | - Krithika Mohan
- Department of Nephrology, Hosmat Hospital, HBR Layout, Bangalore, India
| | - Syeda Ahmad
- Renal-Electrolyte Division, Department of Internal Medicine, University of Pittsburgh, PA
| | - Matthias T F Wolf
- Pediatric Nephrology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX.
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Franken GAC, Huynen MA, Martínez-Cruz LA, Bindels RJM, de Baaij JHF. Structural and functional comparison of magnesium transporters throughout evolution. Cell Mol Life Sci 2022; 79:418. [PMID: 35819535 PMCID: PMC9276622 DOI: 10.1007/s00018-022-04442-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/22/2022] [Accepted: 06/21/2022] [Indexed: 12/16/2022]
Abstract
Magnesium (Mg2+) is the most prevalent divalent intracellular cation. As co-factor in many enzymatic reactions, Mg2+ is essential for protein synthesis, energy production, and DNA stability. Disturbances in intracellular Mg2+ concentrations, therefore, unequivocally result in delayed cell growth and metabolic defects. To maintain physiological Mg2+ levels, all organisms rely on balanced Mg2+ influx and efflux via Mg2+ channels and transporters. This review compares the structure and the function of prokaryotic Mg2+ transporters and their eukaryotic counterparts. In prokaryotes, cellular Mg2+ homeostasis is orchestrated via the CorA, MgtA/B, MgtE, and CorB/C Mg2+ transporters. For CorA, MgtE, and CorB/C, the motifs that form the selectivity pore are conserved during evolution. These findings suggest that CNNM proteins, the vertebrate orthologues of CorB/C, also have Mg2+ transport capacity. Whereas CorA and CorB/C proteins share the gross quaternary structure and functional properties with their respective orthologues, the MgtE channel only shares the selectivity pore with SLC41 Na+/Mg2+ transporters. In eukaryotes, TRPM6 and TRPM7 Mg2+ channels provide an additional Mg2+ transport mechanism, consisting of a fusion of channel with a kinase. The unique features these TRP channels allow the integration of hormonal, cellular, and transcriptional regulatory pathways that determine their Mg2+ transport capacity. Our review demonstrates that understanding the structure and function of prokaryotic magnesiotropic proteins aids in our basic understanding of Mg2+ transport.
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Affiliation(s)
- G A C Franken
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - M A Huynen
- Center for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - L A Martínez-Cruz
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Bizkaia Science and Technology Park, Derio, 48160, Bizkaia, Spain
| | - R J M Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - J H F de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands.
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Integrated Analysis of mRNAs and Long Non-Coding RNAs Expression of Oviduct That Provides Novel Insights into the Prolificacy Mechanism of Goat ( Capra hircus). Genes (Basel) 2022; 13:genes13061031. [PMID: 35741792 PMCID: PMC9222479 DOI: 10.3390/genes13061031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 05/27/2022] [Accepted: 06/06/2022] [Indexed: 02/04/2023] Open
Abstract
Artificial directional selection has replaced natural selection and resulted in trait differences across breeds in domestic animal breeding. However, the molecular mechanism by which the oviduct regulates litter size remains largely elusive in goats during the follicular phase. Accumulating data have linked lncRNAs to reproductive activities; however, little is known about the modulation mechanism in the oviduct. Herein, RNA-seq was used to measure mRNA and lncRNA expression levels in low- and high-fecundity goats. We observed distinctive differences in mRNA and lncRNA in terms of different kidding numbers and detected the differential expression of 1640 mRNA transcripts and 271 lncRNA transcripts. Enrichment analysis of differentially expressed mRNAs (DEGs) suggested that multiple pathways, such as the AMPK, PI3K–Akt, calcium signaling pathway, oocyte meiosis, ABC transporter, and ECM–receptor interaction pathways, directly or indirectly affected goat reproduction. Additionally, coexpression of differentially expressed lncRNAs (DEL)-genes analysis showed that XLOC_021615, XLOC_119780, and XLOC_076450 were trans-acting as the DEGs ATAD2, DEPDC5, and TRPM6, respectively, and could regulate embryo development. Moreover, XLOC_020079, XLOC_107361, XLOC_169844, XLOC_252348 were the trans-regulated elements of the DEGs ARHGEF2 and RAPGEF6, and the target DEGs CPEB3 of XLOC_089239, XLOC_090063, XLOC_107409, XLOC_153574, XLOC_211271, XLOC_251687 were associated with prolificacy. Collectively, our study has offered a thorough dissection of the oviduct lncRNA and mRNA landscapes in goats. These results could serve as potential targets of the oviduct affecting fertility in goats.
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Kim EY, Lee JM. Transcriptional Control of Trpm6 by the Nuclear Receptor FXR. Int J Mol Sci 2022; 23:ijms23041980. [PMID: 35216094 PMCID: PMC8874704 DOI: 10.3390/ijms23041980] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 02/03/2022] [Accepted: 02/08/2022] [Indexed: 12/12/2022] Open
Abstract
Farnesoid x receptor (FXR) is a nuclear bile acid receptor that belongs to the nuclear receptor superfamily. It plays an essential role in bile acid biosynthesis, lipid and glucose metabolism, liver regeneration, and vertical sleeve gastrectomy. A loss of the FXR gene or dysregulations of FXR-mediated gene expression are associated with the development of progressive familial intrahepatic cholestasis, tumorigenesis, inflammation, and diabetes mellitus. Magnesium ion (Mg2+) is essential for mammalian physiology. Over 600 enzymes are dependent on Mg2+ for their activity. Here, we show that the Trpm6 gene encoding a Mg2+ channel is a direct FXR target gene in the intestinal epithelial cells of mice. FXR expressed in the intestinal epithelial cells is absolutely required for sustaining a basal expression of intestinal Trpm6 that can be robustly induced by the treatment of GW4064, a synthetic FXR agonist. Analysis of FXR ChIP-seq data revealed that intron regions of Trpm6 contain two prominent FXR binding peaks. Among them, the proximal peak from the transcription start site contains a functional inverted repeat 1 (IR1) response element that directly binds to the FXR-RXRα heterodimer. Based on these results, we proposed that an intestinal FXR-TRPM6 axis may link a bile acid signaling to Mg2+ homeostasis.
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Affiliation(s)
- Eun Young Kim
- Department of Biochemistry and Cell Biology, Cell and Matrix Research Institute, School of Medicine, Kyungpook National University, Daegu 41944, Korea;
| | - Jae Man Lee
- Department of Biochemistry and Cell Biology, Cell and Matrix Research Institute, School of Medicine, Kyungpook National University, Daegu 41944, Korea;
- BK21 FOUR KNU Biomedical Convergence Program, Department of Biomedical Science, Kyungpook National University, Daegu 41944, Korea
- Correspondence: ; Tel.: +82-53-420-4826
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9
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Forbes EM, Bakrania BA, Steane SE, Moritz KM, Lingwood BE, Eiby YA. Expression of TRPM6 and TRPM7 in the preterm piglet heart. Front Pediatr 2022; 10:891722. [PMID: 36081632 PMCID: PMC9445433 DOI: 10.3389/fped.2022.891722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 08/01/2022] [Indexed: 11/13/2022] Open
Abstract
Preterm infants are at increased risk of death and disability, and cardiovascular instability after birth is a contributing factor. Immaturity of calcium handling in the preterm heart may limit myocardial contractility and cardiac output. Two transmembrane cation channels, TRPM6 and TRPM7, may regulate intracellular cardiac calcium in the neonatal period. The aim of this study was to determine TRPM6 and TRPM7 mRNA expression in piglet hearts in late gestation, and the effects of sex, maternal glucocorticoids, and the transition to extrauterine life. Left and right ventricular tissue was collected at a range of gestational ages from cesarean delivered piglets at birth and at 6 h old. Additional groups included piglets exposed to maternal glucocorticoid treatment and spontaneously born term piglets at 12-24 h old. TRPM6 and TRPM7 mRNA expression was measured using RT-qPCR. Males had significantly lower TRPM7 expression in the left ventricle across all gestational ages compared to females. At term, both ventricles had higher TRPM7 expression at 6 h old than at birth. In preterm piglets, TRPM7 expression only increased postnatally in the right ventricle following maternal glucocorticoid exposure. At 12-24 h old, TRPM7 expression in both ventricles was lower than levels in 6 h old term Caesar piglets (113 days). Male preterm piglets may have immature myocardial Ca2+ handling and this could contribute to their poorer outcomes. Increased TRPM7 expression is the mature response to birth that is missing in preterm neonates. TRPM7 could serve as a novel target to improve cardiac function in preterm neonates.
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Affiliation(s)
- Elizabeth M Forbes
- Queensland Children's Hospital, Brisbane, QLD, Australia.,UQ Centre for Clinical Research and Perinatal Research Centre, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Bhavisha A Bakrania
- UQ Centre for Clinical Research and Perinatal Research Centre, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Sarah E Steane
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Karen M Moritz
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia.,Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Barbara E Lingwood
- UQ Centre for Clinical Research and Perinatal Research Centre, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Yvonne A Eiby
- UQ Centre for Clinical Research and Perinatal Research Centre, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
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10
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Han Y, Zhao Y, Wang H, Huo L. Case Report: Novel TRPM6 Mutations Cause Hereditary Hypomagnesemia With Secondary Hypocalcemia in a Chinese Family and a Literature Review. Front Pediatr 2022; 10:912524. [PMID: 35903165 PMCID: PMC9315244 DOI: 10.3389/fped.2022.912524] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 06/14/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Hereditary hypomagnesemia with secondary hypocalcemia (HSH) is a rare autosomal recessive disease due to biallelic TRPM6 mutations. Although the reports of HSH caused by TRPM6 mutations are not very rare, the age of onset in previously reported HSH cases were <1 year. METHODS We collected and analyzed the clinical data of twin brothers with onset age over 1 year old and performed whole exome sequencing in the patients and their parents. Confirmed by Sanger sequencing, missense mutation was analyzed in silico. We also searched Pubmed, and extracted clinical data from case reports and case series with full text in English, reporting original data of patients with TRPM6 mutations. RESULTS The twin patients had canonical HSH phenotype with compound novel TRPM6 mutations, p.T87K and c.705dupT, inherited from their father and mother, respectively. T87 is a highly conserved site and T87K is predicted to cause hydrogen bond disruption. We identified 26 articles published between May 28, 2002 to December 31, 2021 which reported a total of 88 patients with TRPM6 mutation. We found that the most common clinical phenotypes were hypomagnesemia, hypocalcemia, and convulsions. However, the age of onset in HSH patients almost always occurred under 12 months old, the twin patients of our study were 18 and 26 months old at onset. CONCLUSION We identified two novel TRPM6 mutations in a Chinses family with HSH, and showed that the age of onset with c.704c-c.705(exon7)insT and c.260(exon4)C>A mutation in TRPM6 was much later than other mutations and would be much less serious.
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Affiliation(s)
- Yiran Han
- Department of Pediatrics, Shengjing Hospital of China Medical University, Shenyang, China
| | - Yajuan Zhao
- Department of Pediatrics, Shengjing Hospital of China Medical University, Shenyang, China
| | - Hua Wang
- Department of Pediatrics, Shengjing Hospital of China Medical University, Shenyang, China
| | - Liang Huo
- Department of Pediatrics, Shengjing Hospital of China Medical University, Shenyang, China
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Trophectoderm cell failure leads to peri-implantation lethality in Trpm7-deficient mouse embryos. Cell Rep 2021; 37:109851. [PMID: 34686339 DOI: 10.1016/j.celrep.2021.109851] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 07/28/2021] [Accepted: 09/28/2021] [Indexed: 11/24/2022] Open
Abstract
Early embryogenesis depends on proper control of intracellular homeostasis of ions including Ca2+ and Mg2+. Deletion of the Ca2+ and Mg2+ conducting the TRPM7 channel is embryonically lethal in mice but leaves compaction, blastomere polarization, blastocoel formation, and correct specification of the lineages of the trophectoderm and inner cell mass unaltered despite that free cytoplasmic Ca2+ and Mg2+ is reduced at the two-cell stage. Although Trpm7-/- embryos are able to hatch from the zona pellucida, no expansion of Trpm7-/- trophoblast cells can be observed, and Trpm7-/- embryos are not identifiable in utero at E6.5 or later. Given the proliferation and adhesion defect of Trpm7-/- trophoblast stem cells and the ability of Trpm7-/- ESCs to develop to embryos in tetraploid embryo complementation assays, we postulate a critical role of TRPM7 in trophectoderm cells and their failure during implantation as the most likely explanation of the developmental arrest of Trpm7-deficient mouse embryos.
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Li X, Bao S, Wang W, Shi X, Hu Y, Li F, Zhao Q, Zheng F, Lin Z. Case Report: CNNM2 Mutations Cause Damaged Brain Development and Intractable Epilepsy in a Patient Without Hypomagnesemia. Front Genet 2021; 12:705734. [PMID: 34490037 PMCID: PMC8417836 DOI: 10.3389/fgene.2021.705734] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 07/29/2021] [Indexed: 11/24/2022] Open
Abstract
A series of neurological manifestations such as intellectual disability and epilepsy are closely related to hypomagnesemia. Cyclin M2 (CNNM2) proteins, as a member of magnesium (Mg2+) transporters, were found along the basolateral membrane of distal renal tubules and involved in the reabsorption of Mg2+. Homozygous and heterozygous variants in CNNM2 reported so far were responsible for a variable degree of hypomagnesemia, several of which also showed varying degrees of neurological phenotypes such as intellectual disability and epilepsy. Here, we report a de novo heterozygous CNNM2 variant (c.2228C > T, p.Ser743Phe) in a Chinese patient, which is the variant located in the cyclic nucleotide monophosphate-binding homology (CNBH) domain of CNNM2 proteins. The patient presented with mild intellectual disability and refractory epilepsy but without hypomagnesemia. Thus, we reviewed the literature and analyzed the phenotypes related to CNNM2 variants, and then concluded that the number of variant alleles and the changed protein domains correlates with the severity of the disease, and speculated that the CNBH domain of CNNM2 possibly plays a limited role in Mg2+ transport but a significant role in brain development. Furthermore, it can be speculated that neurological phenotypes such as intellectual disability and seizures can be purely caused by CNNM2 variants.
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Affiliation(s)
- Xiucui Li
- Department of Pediatric Neurology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Shijia Bao
- Department of Clinical Medicine, Wenzhou Medical University, Wenzhou, China
| | - Wei Wang
- Department of Pediatric Orthopedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Xulai Shi
- Department of Pediatric Neurology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Ying Hu
- Department of Pediatric Neurology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Feng Li
- Department of Pediatric Neurology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Qianlei Zhao
- Department of Pediatric Neurology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Feixia Zheng
- Department of Pediatric Neurology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zhongdong Lin
- Department of Pediatric Neurology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
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13
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Bayramoğlu E, Keskin M, Aycan Z, Savaş-Erdeve Ş, Çetinkaya S. Long-term Clinical Follow-up of Patients with Familial Hypomagnesemia with Secondary Hypocalcemia. J Clin Res Pediatr Endocrinol 2021; 13:300-307. [PMID: 33565749 PMCID: PMC8388043 DOI: 10.4274/jcrpe.galenos.2021.2020.0192] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
OBJECTIVE Familial hypomagnesemia with secondary hypocalcemia (HSH) is an autosomal recessive disease caused by a mutation in the transient receptor potential melastatin 6 (TRPM6) gene and is characterized by selective magnesium malabsorption. Affected cases are usually diagnosed during infancy and usually present with seizures due to hypocalcemia and hypomagnesemia. Irreversible neurological deficits and arrhythmias can be observed without appropriate treatment. The aim was to evaluate the long-term follow-up of patients with genetically confirmed HSH. METHODS A total of six patients with HSH, two of whom were siblings, were included. Age at diagnosis, clinical, laboratory and follow-up data on admission were recorded. All 39 exons of the TRPM6 gene and flanking exon-intron junctions from genomic DNA were amplified and sequenced in all cases. RESULTS The median (range) follow-up duration was 12.1 (7.6-21.7) years. All cases were diagnosed in infancy. Four different mutations, three of which had not been previously reported, were detected in the TRPM6 gene. Treatment compliance was good and there were no severe complications in the long-term follow-up of cases. However, mental retardation, specific learning difficulty and attention deficit/hyperactive disorder were observed as comorbidities. CONCLUSION Of the four different TRPM6 mutations in this small cohort, three had not been previously reported. The long-term prognosis of HSH appears to be good, given early diagnosis and good treatment compliance. This long-term follow-up and prognostic data and the three novel mutations will contribute to the published evidence concerning this rare condition, HSH, and it is hoped will prevent negative outcomes.
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Affiliation(s)
- Elvan Bayramoğlu
- University of Health Sciences Turkey, Ankara Dr. Sami Ulus Obstetrics and Gynecology and Child Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey,* Address for Correspondence: University of Health Sciences Turkey, Ankara Dr. Sami Ulus Obstetrics and Gynecology and Child Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey Phone: +90 312 305 65 13 E-mail:
| | - Melikşah Keskin
- University of Health Sciences Turkey, Ankara Dr. Sami Ulus Obstetrics and Gynecology and Child Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey
| | - Zehra Aycan
- University of Health Sciences Turkey, Ankara Dr. Sami Ulus Obstetrics and Gynecology and Child Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey
| | - Şenay Savaş-Erdeve
- University of Health Sciences Turkey, Ankara Dr. Sami Ulus Obstetrics and Gynecology and Child Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey
| | - Semra Çetinkaya
- University of Health Sciences Turkey, Ankara Dr. Sami Ulus Obstetrics and Gynecology and Child Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey
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14
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Funato Y, Yamazaki D, Okuzaki D, Yamamoto N, Miki H. Importance of the renal ion channel TRPM6 in the circadian secretion of renin to raise blood pressure. Nat Commun 2021; 12:3683. [PMID: 34140503 PMCID: PMC8211686 DOI: 10.1038/s41467-021-24063-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 06/01/2021] [Indexed: 11/30/2022] Open
Abstract
Blood pressure has a daily pattern, with higher values in the active period. Its elevation at the onset of the active period substantially increases the risk of fatal cardiovascular events. Renin secretion stimulated by renal sympathetic neurons is considered essential to this process; however, its regulatory mechanism remains largely unknown. Here, we show the importance of transient receptor potential melastatin-related 6 (TRPM6), a Mg2+-permeable cation channel, in augmenting renin secretion in the active period. TRPM6 expression is significantly reduced in the distal convoluted tubule of hypotensive Cnnm2-deficient mice. We generate kidney-specific Trpm6-deficient mice and observe a decrease in blood pressure and a disappearance of its circadian variation. Consistently, renin secretion is not augmented in the active period. Furthermore, renin secretion after pharmacological activation of β-adrenoreceptor, the target of neuronal stimulation, is abrogated, and the receptor expression is decreased in renin-secreting cells. These results indicate crucial roles of TRPM6 in the circadian regulation of blood pressure. Circadian variation of blood pressure, with higher values in the active period, is associated with the risk of fatal cardiovascular events. Here, we show the importance of renal TRPM6, a Magnesium-permeable cation channel, in raising blood pressure by stimulating renin secretion.
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Affiliation(s)
- Yosuke Funato
- Department of Cellular Regulation, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Daisuke Yamazaki
- Department of Cellular Regulation, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Daisuke Okuzaki
- Genome Information Research Center, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Nobuhiko Yamamoto
- Neuroscience Laboratories, Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Hiroaki Miki
- Department of Cellular Regulation, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
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15
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Mapping the expression of transient receptor potential channels across murine placental development. Cell Mol Life Sci 2021; 78:4993-5014. [PMID: 33884443 PMCID: PMC8233283 DOI: 10.1007/s00018-021-03837-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 03/17/2021] [Accepted: 04/08/2021] [Indexed: 12/12/2022]
Abstract
Transient receptor potential (TRP) channels play prominent roles in ion homeostasis by their ability to control cation influx. Mouse placentation is governed by the processes of trophoblast proliferation, invasion, differentiation, and fusion, all of which require calcium signaling. Although certain TRP channels have been shown to contribute to maternal–fetal transport of magnesium and calcium, a role for TRP channels in specific trophoblast functions has been disregarded. Using qRT-PCR and in situ hybridisation, the spatio-temporal expression pattern of TRP channels in the mouse placenta across gestation (E10.5–E18.5) was assessed. Prominent expression was observed for Trpv2, Trpm6, and Trpm7. Calcium microfluorimetry in primary trophoblast cells isolated at E14.5 of gestation further revealed the functional activity of TRPV2 and TRPM7. Finally, comparing TRP channels expression in mouse trophoblast stem cells (mTSCs) and mouse embryonic stem cells (mESC) confirmed the specific expression of TRPV2 during placental development. Moreover, TRP channel expression was similar in mTSCs compared to primary trophoblasts and validate mTSC as a model to study TRP channels in placental development. Collectivity, our results identify a specific spatio-temporal TRP channel expression pattern in trophoblasts, suggesting a possible involvement in regulating the process of placentation.
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16
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Cyclin M2 (CNNM2) knockout mice show mild hypomagnesaemia and developmental defects. Sci Rep 2021; 11:8217. [PMID: 33859252 PMCID: PMC8050252 DOI: 10.1038/s41598-021-87548-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Accepted: 03/26/2021] [Indexed: 02/02/2023] Open
Abstract
Patients with mutations in Cyclin M2 (CNNM2) suffer from hypomagnesaemia, seizures, and intellectual disability. Although the molecular function of CNNM2 is under debate, the protein is considered essential for renal Mg2+ reabsorption. Here, we used a Cnnm2 knock out mouse model, generated by CRISPR/Cas9 technology, to assess the role of CNNM2 in Mg2+ homeostasis. Breeding Cnnm2+/- mice resulted in a Mendelian distribution at embryonic day 18. Nevertheless, only four Cnnm2-/- pups were born alive. The Cnnm2-/- pups had a significantly lower serum Mg2+ concentration compared to wildtype littermates. Subsequently, adult Cnnm2+/- mice were fed with low, control, or high Mg2+ diets for two weeks. Adult Cnnm2+/- mice showed mild hypomagnesaemia compared to Cnnm2+/+ mice and increased serum Ca2+ levels, independent of dietary Mg2+ intake. Faecal analysis displayed increased Mg2+ and Ca2+ excretion in the Cnnm2+/- mice. Transcriptional profiling of Trpm6, Trpm7, and Slc41a1 in kidneys and colon did not reveal effects based on genotype. Microcomputed tomography analysis of the femurs demonstrated equal bone morphology and density. In conclusion, CNNM2 is vital for embryonic development and Mg2+ homeostasis. Our data suggest a previously undescribed role of CNNM2 in the intestine, which may contribute to the Mg2+ deficiency in mice and patients.
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17
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Runnels LW, Komiya Y. TRPM6 and TRPM7: Novel players in cell intercalation during vertebrate embryonic development. Dev Dyn 2020; 249:912-923. [PMID: 32315468 DOI: 10.1002/dvdy.182] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 04/09/2020] [Accepted: 04/11/2020] [Indexed: 12/16/2022] Open
Abstract
A common theme in organogenesis is how the final structure of organs emerge from epithelial tube structures, with the formation of the neural tube being one of the best examples. Two types of cell movements co-occur during neural tube closure involving the migration of cells toward the midline of the embryo (mediolateral intercalation or convergent extension) as well as the deep movement of cells from inside the embryo to the outside of the lateral side of the neural plate (radial intercalation). Failure of either type of cell movement will prevent neural tube closure, which can produce a range of neural tube defects (NTDs), a common congenital disease in humans. Numerous studies have identified signaling pathways that regulate mediolateral intercalation during neural tube closure. Less understood are the pathways that govern radial intercalation. Using the Xenopus laevis system, our group reported the identification of transient receptor potential (TRP) channels, TRPM6 and TRPM7, and the Mg2+ ion they conduct, as novel and key factors regulating both mediolateral and radial intercalation during neural tube closure. Here we broadly discuss tubulogenesis and cell intercalation from the perspective of neural tube closure and the respective roles of TRPM7 and TRPM6 in this critical embryonic process.
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Affiliation(s)
- Loren W Runnels
- Department of Pharmacology, Rutgers-Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
| | - Yuko Komiya
- Department of Pharmacology, Rutgers-Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
- Faculty of Industrial Science and Technology, Tokyo University of Science, Yamakoshi-gun, Hokkaido, Japan
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18
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Zou J, Wang F, Yang X, Wang H, Niswander L, Zhang T, Li H. Association between rare variants in specific functional pathways and human neural tube defects multiple subphenotypes. Neural Dev 2020; 15:8. [PMID: 32650820 PMCID: PMC7353782 DOI: 10.1186/s13064-020-00145-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 05/13/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Neural tube defects (NTDs) are failure of neural tube closure, which includes multiple central nervous system phenotypes. More than 300 mouse mutant strains exhibits NTDs phenotypes and give us some clues to establish association between biological functions and subphenotypes. However, the knowledge about association in human remains still very poor. METHODS High throughput targeted genome DNA sequencing were performed on 280 neural tube closure-related genes in 355 NTDs cases and 225 ethnicity matched controls, RESULTS: We explored that potential damaging rare variants in genes functioning in chromatin modification, apoptosis, retinoid metabolism and lipid metabolism are associated with human NTDs. Importantly, our data indicate that except for planar cell polarity pathway, craniorachischisis is also genetically related with chromatin modification and retinoid metabolism. Furthermore, single phenotype in cranial or spinal regions displays significant association with specific biological function, such as anencephaly is associated with potentially damaging rare variants in genes functioning in chromatin modification, encephalocele is associated with apoptosis, retinoid metabolism and one carbon metabolism, spina bifida aperta and spina bifida cystica are associated with apoptosis; lumbar sacral spina bifida aperta and spina bifida occulta are associated with lipid metabolism. By contrast, complex phenotypes in both cranial and spinal regions display association with various biological functions given the different phenotypes. CONCLUSIONS Our study links genetic variant to subphenotypes of human NTDs and provides a preliminary but direct clue to investigate pathogenic mechanism for human NTDs.
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Affiliation(s)
- Jizhen Zou
- Beijing Municipal Key Laboratory of Child Development and Nutriomics, Capital Institute of Pediatrics, Beijing, 100020, China.
| | - Fang Wang
- Beijing Municipal Key Laboratory of Child Development and Nutriomics, Capital Institute of Pediatrics, Beijing, 100020, China
| | - Xueyan Yang
- State Key Laboratory of Genetic Engineering and MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Hongyan Wang
- Obstetrics and Gynecology Hospital, Key Lab of Reproduction Regulation of NPFPC in SIPPR, Institute of Reproduction and Development, Fudan University, Shanghai, 200011, China
| | - Lee Niswander
- Molecular, Cellular and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, 80309, USA
| | - Ting Zhang
- Beijing Municipal Key Laboratory of Child Development and Nutriomics, Capital Institute of Pediatrics, Beijing, 100020, China
| | - Huili Li
- Beijing Municipal Key Laboratory of Child Development and Nutriomics, Capital Institute of Pediatrics, Beijing, 100020, China. .,Molecular, Cellular and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, 80309, USA.
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19
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van der Wijst J, Belge H, Bindels RJM, Devuyst O. Learning Physiology From Inherited Kidney Disorders. Physiol Rev 2019; 99:1575-1653. [PMID: 31215303 DOI: 10.1152/physrev.00008.2018] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The identification of genes causing inherited kidney diseases yielded crucial insights in the molecular basis of disease and improved our understanding of physiological processes that operate in the kidney. Monogenic kidney disorders are caused by mutations in genes coding for a large variety of proteins including receptors, channels and transporters, enzymes, transcription factors, and structural components, operating in specialized cell types that perform highly regulated homeostatic functions. Common variants in some of these genes are also associated with complex traits, as evidenced by genome-wide association studies in the general population. In this review, we discuss how the molecular genetics of inherited disorders affecting different tubular segments of the nephron improved our understanding of various transport processes and of their involvement in homeostasis, while providing novel therapeutic targets. These include inherited disorders causing a dysfunction of the proximal tubule (renal Fanconi syndrome), with emphasis on epithelial differentiation and receptor-mediated endocytosis, or affecting the reabsorption of glucose, the handling of uric acid, and the reabsorption of sodium, calcium, and magnesium along the kidney tubule.
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Affiliation(s)
- Jenny van der Wijst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - Hendrica Belge
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - René J M Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - Olivier Devuyst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
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20
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Dhakal S, Lee Y. Transient Receptor Potential Channels and Metabolism. Mol Cells 2019; 42:569-578. [PMID: 31446746 PMCID: PMC6715338 DOI: 10.14348/molcells.2019.0007] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Revised: 07/27/2019] [Accepted: 08/13/2019] [Indexed: 12/12/2022] Open
Abstract
Transient receptor potential (TRP) channels are nonselective cationic channels, conserved among flies to humans. Most TRP channels have well known functions in chemosensation, thermosensation, and mechanosensation. In addition to being sensing environmental changes, many TRP channels are also internal sensors that help maintain homeostasis. Recent improvements to analytical methods for genomics and metabolomics allow us to investigate these channels in both mutant animals and humans. In this review, we discuss three aspects of TRP channels, which are their role in metabolism, their functional characteristics, and their role in metabolic syndrome. First, we introduce each TRP channel superfamily and their particular roles in metabolism. Second, we provide evidence for which metabolites TRP channels affect, such as lipids or glucose. Third, we discuss correlations between TRP channels and obesity, diabetes, and mucolipidosis. The cellular metabolism of TRP channels gives us possible therapeutic approaches for an effective prophylaxis of metabolic syndromes.
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Affiliation(s)
- Subash Dhakal
- Department of Bio and Fermentation Convergence Technology, Kookmin University, BK21 PLUS Project, Seoul 02707,
Korea
| | - Youngseok Lee
- Department of Bio and Fermentation Convergence Technology, Kookmin University, BK21 PLUS Project, Seoul 02707,
Korea
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21
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Manabe A, Furukawa C, Hasegawa H, Matsunaga T, Endo S, Ikari A. Upregulation of transient receptor potential melastatin 6 channel expression by rosiglitazone and all‐
trans
‐retinoic acid in erlotinib‐treated renal tubular epithelial cells. J Cell Physiol 2018; 234:8951-8962. [DOI: 10.1002/jcp.27565] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 09/13/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Aya Manabe
- Department of Biopharmaceutical Sciences Laboratory of Biochemistry, Gifu Pharmaceutical University Gifu Japan
| | - Chisa Furukawa
- Department of Biopharmaceutical Sciences Laboratory of Biochemistry, Gifu Pharmaceutical University Gifu Japan
| | - Hajime Hasegawa
- Department of Nephrology and Hypertension Saitama Medical Center, Saitama Medical University Saitama Japan
| | - Toshiyuki Matsunaga
- Department of Biopharmaceutical Sciences Laboratory of Biochemistry, Gifu Pharmaceutical University Gifu Japan
| | - Satoshi Endo
- Department of Biopharmaceutical Sciences Laboratory of Biochemistry, Gifu Pharmaceutical University Gifu Japan
| | - Akira Ikari
- Department of Biopharmaceutical Sciences Laboratory of Biochemistry, Gifu Pharmaceutical University Gifu Japan
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22
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Nie M, Bal MS, Liu J, Yang Z, Rivera C, Wu XR, Hoenderop JGJ, Bindels RJM, Marciano DK, Wolf MTF. Uromodulin regulates renal magnesium homeostasis through the ion channel transient receptor potential melastatin 6 (TRPM6). J Biol Chem 2018; 293:16488-16502. [PMID: 30139743 DOI: 10.1074/jbc.ra118.003950] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 08/21/2018] [Indexed: 12/15/2022] Open
Abstract
Up to 15% of the population have mild to moderate chronic hypomagnesemia, which is associated with type 2 diabetes mellitus, hypertension, metabolic syndrome, and chronic kidney disease. The kidney is the key organ for magnesium homeostasis, but our understanding of renal magnesium regulation is very limited. Uromodulin (UMOD) is the most abundant urinary protein in humans, and here we report that UMOD has a role in renal magnesium homeostasis. Umod-knockout (Umod -/-) mice excreted more urinary magnesium than WT mice and displayed up-regulation of genes promoting magnesium absorption. The majority of magnesium is absorbed in the thick ascending limb. However, both mouse strains responded similarly to the diuretic agent furosemide, indicating appropriate function of the thick ascending limb in the Umod -/- mice. Magnesium absorption is fine-tuned in the distal convoluted tubule (DCT) via the apical magnesium channel transient receptor potential melastatin 6 (TRPM6). We observed decreased apical Trpm6 staining in the DCT of Umod -/- mice. Applying biotinylation assays and whole-cell patch-clamp recordings, we found that UMOD enhances TRPM6 cell-surface abundance and current density from the extracellular space. UMOD physically interacted with TRPM6 and thereby impaired dynamin-dependent TRPM6 endocytosis. WT mice fed a low-magnesium diet had an increased urinary UMOD secretion compared with the same mice on a regular diet. Our results suggest that increased urinary UMOD secretion in low-magnesium states reduces TRPM6 endocytosis and thereby up-regulates TRPM6 cell-surface abundance to defend against further urinary magnesium losses.
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Affiliation(s)
| | | | - Jie Liu
- From the Departments of Pediatrics and
| | - Zhufeng Yang
- Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | | | - Xue-Ru Wu
- the Departments of Urology and Pathology, New York University School of Medicine, New York, New York 10016, and
| | - Joost G J Hoenderop
- the Department of Physiology, Radboud Center for Molecular Life Sciences, Radboud University Medical Centre, 6525 GA Nijmegen, The Netherlands
| | - René J M Bindels
- the Department of Physiology, Radboud Center for Molecular Life Sciences, Radboud University Medical Centre, 6525 GA Nijmegen, The Netherlands
| | - Denise K Marciano
- Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390
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23
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De Clercq K, Vriens J. Establishing life is a calcium-dependent TRiP: Transient receptor potential channels in reproduction. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1865:1815-1829. [PMID: 30798946 DOI: 10.1016/j.bbamcr.2018.08.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 08/03/2018] [Accepted: 08/04/2018] [Indexed: 12/21/2022]
Abstract
Calcium plays a key role in many different steps of the reproduction process, from germ cell maturation to placental development. However, the exact function and regulation of calcium throughout subsequent reproductive events remains rather enigmatic. Successful pregnancy requires the establishment of a complex dialogue between the implanting embryo and the endometrium. On the one hand, endometrial cell will undergo massive changes to support an implanting embryo, including stromal cell decidualization. On the other hand, trophoblast cells from the trophectoderm surrounding the inner cell mass will differentiate and acquire new functions such as hormone secretion, invasion and migration. The need for calcium in the different gestational processes implicates the presence of specialized ion channels to regulate calcium homeostasis. The superfamily of transient receptor potential (TRP) channels is a class of calcium permeable ion channels that is involved in the transformation of extracellular stimuli into the influx of calcium, inducing and coordinating underlying signaling pathways. Although the necessity of calcium throughout reproduction cannot be negated, the expression and functionality of TRP channels throughout gestation remains elusive. This review provides an overview of the current evidence regarding the expression and function of TRP channels in reproduction.
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Affiliation(s)
- Katrien De Clercq
- Laboratory of Endometrium, Endometriosis & Reproductive Medicine, Department Development & Regeneration, KU Leuven, G-PURE, Leuven, Belgium; Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven, VIB Centre for Brain & Disease Research, Leuven, Belgium
| | - Joris Vriens
- Laboratory of Endometrium, Endometriosis & Reproductive Medicine, Department Development & Regeneration, KU Leuven, G-PURE, Leuven, Belgium.
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Accogli A, Scala M, Calcagno A, Napoli F, Di Iorgi N, Arrigo S, Mancardi MM, Prato G, Pisciotta L, Nagel M, Severino M, Capra V. CNNM2 homozygous mutations cause severe refractory hypomagnesemia, epileptic encephalopathy and brain malformations. Eur J Med Genet 2018; 62:198-203. [PMID: 30026055 DOI: 10.1016/j.ejmg.2018.07.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 07/01/2018] [Accepted: 07/14/2018] [Indexed: 12/19/2022]
Abstract
Magnesium (Mg2+) plays a crucial role in many biological processes especially in the brain, heart and skeletal muscle. Mg2+ homeostasis is regulated by intestinal absorption and renal reabsorption, involving a combination of different epithelial transport pathways. Mutations in any of these transporters result in hypomagnesemia with variable clinical presentations. Among these, CNNM2 is found along the basolateral membrane of distal tubular segments where it is involved in Mg2+ reabsorption. To date, heterozygous mutations in CNNM2 have been associated with a variable phenotype, ranging from isolated hypomagnesemia to intellectual disability and epilepsy. The only homozygous mutation reported so far, is responsible for hypomagnesemia associated with a severe neurological phenotype characterized by refractory epilepsy, microcephaly, severe global developmental delay and intellectual disability. Here, we report the second homozygous CNNM2 mutation (c.1642G > A,p.Val548Met) in a Moroccan patient, presenting with hypomagnesemia and severe epileptic encephalopathy. Thus, we review and discuss the phenotypic spectrum associated with CNNM2 mutations.
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Affiliation(s)
- Andrea Accogli
- UOC Neurochirurgia, Istituto Giannina Gaslini, Genova, Italy; Università degli studi di Genova, Italy
| | - Marcello Scala
- UOC Neurochirurgia, Istituto Giannina Gaslini, Genova, Italy; Università degli studi di Genova, Italy
| | | | - Flavia Napoli
- UOC Clinica Pediatrica, Istituto Giannina Gaslini, Genova, Italy
| | - Natascia Di Iorgi
- Università degli studi di Genova, Italy; UOC Clinica Pediatrica, Istituto Giannina Gaslini, Genova, Italy
| | - Serena Arrigo
- UOC Gastroenterologia and Endoscopia Pediatrica, Istituto Giannina Gaslini, Genova, Italy
| | | | - Giulia Prato
- UOC Neuropsichiatria Infantile - Centro Epilessia, Istituto Giannina Gaslini, Genova, Italy
| | - Livia Pisciotta
- Università degli studi di Genova, Italy; UOC Neuropsichiatria Infantile - Centro Epilessia, Istituto Giannina Gaslini, Genova, Italy
| | - Mato Nagel
- Center for Nephrology and Metabolic Disorders, Weisswasser, Germany
| | | | - Valeria Capra
- UOC Neurochirurgia, Istituto Giannina Gaslini, Genova, Italy.
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Morgan CP, Zhao H, LeMasurier M, Xiong W, Pan B, Kazmierczak P, Avenarius MR, Bateschell M, Larisch R, Ricci AJ, Müller U, Barr-Gillespie PG. TRPV6, TRPM6 and TRPM7 Do Not Contribute to Hair-Cell Mechanotransduction. Front Cell Neurosci 2018; 12:41. [PMID: 29515374 PMCID: PMC5826258 DOI: 10.3389/fncel.2018.00041] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 02/01/2018] [Indexed: 12/02/2022] Open
Abstract
Hair cells of the inner ear transduce mechanical stimuli like sound or head movements into electrical signals, which are propagated to the central nervous system. The hair-cell mechanotransduction channel remains unidentified. We tested whether three transient receptor channel (TRP) family members, TRPV6, TRPM6 and TRPM7, were necessary for transduction. TRPV6 interacted with USH1C (harmonin), a scaffolding protein that participates in transduction. Using a cysteine-substitution knock-in mouse line and methanethiosulfonate (MTS) reagents selective for this allele, we found that inhibition of TRPV6 had no effect on transduction in mouse cochlear hair cells. TRPM6 and TRPM7 each interacted with the tip-link component PCDH15 in cultured eukaryotic cells, which suggested they might be part of the transduction complex. Cochlear hair cell transduction was not affected by manipulations of Mg2+, however, which normally perturbs TRPM6 and TRPM7. To definitively examine the role of these two channels in transduction, we showed that deletion of either or both of their genes selectively in hair cells had no effect on auditory function. We suggest that TRPV6, TRPM6 and TRPM7 are unlikely to be the pore-forming subunit of the hair-cell transduction channel.
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Affiliation(s)
- Clive P. Morgan
- Oregon Hearing Research Center & Vollum Institute, Oregon Health & Science University, Portland, OR, United States
| | - Hongyu Zhao
- Oregon Hearing Research Center & Vollum Institute, Oregon Health & Science University, Portland, OR, United States
| | - Meredith LeMasurier
- Oregon Hearing Research Center & Vollum Institute, Oregon Health & Science University, Portland, OR, United States
| | - Wei Xiong
- Department of Neuroscience, Scripps Research Institute, La Jolla, CA, United States
| | - Bifeng Pan
- Department of Otolaryngology, Stanford University, Stanford, CA, United States
| | - Piotr Kazmierczak
- Department of Neuroscience, Scripps Research Institute, La Jolla, CA, United States
| | - Matthew R. Avenarius
- Oregon Hearing Research Center & Vollum Institute, Oregon Health & Science University, Portland, OR, United States
| | - Michael Bateschell
- Oregon Hearing Research Center & Vollum Institute, Oregon Health & Science University, Portland, OR, United States
| | - Ruby Larisch
- Oregon Hearing Research Center & Vollum Institute, Oregon Health & Science University, Portland, OR, United States
| | - Anthony J. Ricci
- Department of Otolaryngology, Stanford University, Stanford, CA, United States
| | - Ulrich Müller
- Department of Neuroscience, Scripps Research Institute, La Jolla, CA, United States
| | - Peter G. Barr-Gillespie
- Oregon Hearing Research Center & Vollum Institute, Oregon Health & Science University, Portland, OR, United States
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Abdullah NL, Mohd-Zin SW, Ahmad-Annuar A, Abdul-Aziz NM. A Novel Occulta-Type Spina Bifida Mediated by Murine Double Heterozygotes EphA2 and EphA4 Receptor Tyrosine Kinases. Front Cell Dev Biol 2018; 5:105. [PMID: 29312933 PMCID: PMC5732981 DOI: 10.3389/fcell.2017.00105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 11/22/2017] [Indexed: 11/27/2022] Open
Abstract
Members of the Eph receptor tyrosine kinase have previously been implicated in cranial neural tube development. Failure of neural tube closure leads to the devastating conditions known as anencephaly and spina bifida. EphA2 and EphA4 are expressed at the tips of the closing spinal neural folds prior and during neural tube closure. We investigated the possible role of murine EphA2 and EphA4 during the last step of primary neural tube closure, which is adhesion and fusion. The individual mouse knockouts of EphA2 and EphA4 per se do not exhibit neural tube defects (NTDs). The embryos generated by the crossing of double heterozygotes Epha2tm1Jrui/+Epha4rb-2J/+ displayed NTDs with a wide degree of severity including close exencephaly and close spina bifida (spina bifida occulta). Interestingly, mutants displaying NTDs had skin covering the underlying lesion. The tissue sections revealed the elevated neural folds had not adhered and fused. The phenotypes seen in Epha2tm1Jrui/+Epha4rb-2J/+ double heterozygous embryos suggest both genes play a compensatory role with each other in the adhesion and fusion of the neural tube. In this study, there exists a >50% penetrance of NTDs in the mouse mutants, which genetically have a single allele each of EphA2 and EphA4 absent.
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Affiliation(s)
- Nor Linda Abdullah
- Faculty of Medicine, Department of Parasitology, University of Malaya, Kuala Lumpur, Malaysia
| | - Siti W Mohd-Zin
- Faculty of Medicine, Department of Parasitology, University of Malaya, Kuala Lumpur, Malaysia
| | - Azlina Ahmad-Annuar
- Faculty of Medicine, Department of Biomedical Science, University of Malaya, Kuala Lumpur, Malaysia
| | - Noraishah M Abdul-Aziz
- Faculty of Medicine, Department of Parasitology, University of Malaya, Kuala Lumpur, Malaysia
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Komiya Y, Bai Z, Cai N, Lou L, Al-Saadi N, Mezzacappa C, Habas R, Runnels LW. A Nonredundant Role for the TRPM6 Channel in Neural Tube Closure. Sci Rep 2017; 7:15623. [PMID: 29142255 PMCID: PMC5688082 DOI: 10.1038/s41598-017-15855-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 10/19/2017] [Indexed: 01/17/2023] Open
Abstract
In humans, germline mutations in Trpm6 cause autosomal dominant hypomagnesemia with secondary hypocalcemia disorder. Loss of Trpm6 in mice also perturbs cellular magnesium homeostasis but additionally results in early embryonic lethality and neural tube closure defects. To define the mechanisms by which TRPM6 influences neural tube closure, we functionally characterized the role of TRPM6 during early embryogenesis in Xenopus laevis. The expression of Xenopus TRPM6 (XTRPM6) is elevated at the onset of gastrulation and is concentrated in the lateral mesoderm and ectoderm at the neurula stage. Loss of XTRPM6 produced gastrulation and neural tube closure defects. Unlike XTRPM6's close homologue XTRPM7, whose loss interferes with mediolateral intercalation, depletion of XTRPM6 but not XTRPM7 disrupted radial intercalation cell movements. A zinc-influx assay demonstrated that TRPM6 has the potential to constitute functional channels in the absence of TRPM7. The results of our study indicate that XTRPM6 regulates radial intercalation with little or no contribution from XTRPM7 in the region lateral to the neural plate, whereas XTRPM7 is mainly involved in regulating mediolateral intercalation in the medial region of the neural plate. We conclude that both TRPM6 and TRPM7 channels function cooperatively but have distinct and essential roles during neural tube closure.
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Affiliation(s)
- Yuko Komiya
- Rutgers-Robert Wood Johnson Medical School, Deptartment of Pharmacology, Piscataway, 08854, USA.
| | - Zhiyong Bai
- Rutgers-Robert Wood Johnson Medical School, Deptartment of Pharmacology, Piscataway, 08854, USA
| | - Na Cai
- Rutgers-Robert Wood Johnson Medical School, Deptartment of Pharmacology, Piscataway, 08854, USA
| | - Liping Lou
- Rutgers-Robert Wood Johnson Medical School, Deptartment of Pharmacology, Piscataway, 08854, USA
| | - Namariq Al-Saadi
- Rutgers-Robert Wood Johnson Medical School, Deptartment of Pharmacology, Piscataway, 08854, USA
| | | | - Raymond Habas
- Temple University, Deptartment of Biology, Philadelphia, 19122, USA.
| | - Loren W Runnels
- Rutgers-Robert Wood Johnson Medical School, Deptartment of Pharmacology, Piscataway, 08854, USA.
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Krapivinsky G, Krapivinsky L, Renthal NE, Santa-Cruz A, Manasian Y, Clapham DE. Histone phosphorylation by TRPM6's cleaved kinase attenuates adjacent arginine methylation to regulate gene expression. Proc Natl Acad Sci U S A 2017; 114:E7092-E7100. [PMID: 28784805 PMCID: PMC5576826 DOI: 10.1073/pnas.1708427114] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
TRPM6 and TRPM7 are members of the melastatin-related transient receptor potential (TRPM) subfamily of ion channels. Deletion of either gene in mice is embryonically lethal. TRPM6/7 are the only known examples of single polypeptides containing both an ion channel pore and a serine/threonine kinase (chanzyme). Here we show that the C-terminal kinase domain of TRPM6 is cleaved from the channel domain in a cell type-specific fashion and is active. Cleavage requires that the channel conductance is functional. The cleaved kinase translocates to the nucleus, where it is strictly localized and phosphorylates specific histone serine and threonine (S/T) residues. TRPM6-cleaved kinases (M6CKs) bind subunits of the protein arginine methyltransferase 5 (PRMT5) molecular complex that make important epigenetic modifications by methylating histone arginine residues. Histone phosphorylation by M6CK results in a dramatic decrease in methylation of arginines adjacent to M6CK-phosphorylated amino acids. Knockout of TRPM6 or inactivation of its kinase results in global changes in histone S/T phosphorylation and changes the transcription of hundreds of genes. We hypothesize that M6CK associates with the PRMT5 molecular complex in the nucleus, directing M6CK to a specific genomic location and providing site-specific histone phosphorylation. M6CK histone phosphorylation, in turn, regulates transcription by attenuating the effect of local arginine methylation.
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Affiliation(s)
- Grigory Krapivinsky
- Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115
- Department of Cardiology, Harvard Medical School, Boston, MA 02115
| | - Luba Krapivinsky
- Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115
- Department of Cardiology, Harvard Medical School, Boston, MA 02115
| | - Nora E Renthal
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115
| | - Ana Santa-Cruz
- Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115
- Department of Cardiology, Harvard Medical School, Boston, MA 02115
| | - Yunona Manasian
- Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115
- Department of Cardiology, Harvard Medical School, Boston, MA 02115
| | - David E Clapham
- Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115;
- Department of Cardiology, Harvard Medical School, Boston, MA 02115
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115
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30
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Ferioli S, Zierler S, Zaißerer J, Schredelseker J, Gudermann T, Chubanov V. TRPM6 and TRPM7 differentially contribute to the relief of heteromeric TRPM6/7 channels from inhibition by cytosolic Mg 2+ and Mg·ATP. Sci Rep 2017; 7:8806. [PMID: 28821869 PMCID: PMC5562840 DOI: 10.1038/s41598-017-08144-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 07/05/2017] [Indexed: 02/04/2023] Open
Abstract
TRPM6 and its homologue TRPM7 are α-kinase-coupled divalent cation-selective channels activated upon reduction of cytosolic levels of Mg2+ and Mg·ATP. TRPM6 is vital for organismal Mg2+ balance. However, mechanistically the cellular role and functional nonredundancy of TRPM6 remain incompletely understood. Comparative analysis of native currents in primary cells from TRPM6- versus TRPM7-deficient mice supported the concept that native TRPM6 primarily functions as a constituent of heteromeric TRPM6/7 channels. However, heterologous expression of the human TRPM6 protein engendered controversial results with respect to channel characteristics including its regulation by Mg2+ and Mg·ATP. To resolve this issue, we cloned the mouse TRPM6 (mTRPM6) cDNA and compared its functional characteristics to mouse TRPM7 (mTRPM7) after heterologous expression. Notably, we observed that mTRPM6 and mTRPM7 differentially regulate properties of heteromeric mTRPM6/7 channels: In the presence of mTRPM7, the extreme sensitivity of functionally expressed homomeric mTRPM6 to Mg2+ is tuned to higher concentrations, whereas mTRPM6 relieves mTRPM7 from the tight inhibition by Mg·ATP. Consequently, the association of mTRPM6 with mTRPM7 allows for high constitutive activity of mTRPM6/7 in the presence of physiological levels of Mg2+ and Mg·ATP, thus laying the mechanistic foundation for constant vectorial Mg2+ transport specifically into epithelial cells.
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Affiliation(s)
- Silvia Ferioli
- Walther Straub Institute of Pharmacology and Toxicology, LMU Munich, Munich, Germany
| | - Susanna Zierler
- Walther Straub Institute of Pharmacology and Toxicology, LMU Munich, Munich, Germany
| | - Joanna Zaißerer
- Walther Straub Institute of Pharmacology and Toxicology, LMU Munich, Munich, Germany
| | - Johann Schredelseker
- Walther Straub Institute of Pharmacology and Toxicology, LMU Munich, Munich, Germany
| | - Thomas Gudermann
- Walther Straub Institute of Pharmacology and Toxicology, LMU Munich, Munich, Germany. .,German Center for Lung Research, Munich, Germany. .,German Centre for Cardiovascular Research, Munich Heart Alliance, Munich, Germany.
| | - Vladimir Chubanov
- Walther Straub Institute of Pharmacology and Toxicology, LMU Munich, Munich, Germany.
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Actions and Regulation of Ionotropic Cannabinoid Receptors. ADVANCES IN PHARMACOLOGY 2017; 80:249-289. [PMID: 28826537 DOI: 10.1016/bs.apha.2017.04.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Almost three decades have passed since the identification of the two specific metabotropic receptors mediating cannabinoid pharmacology. Thereafter, many cannabinoid effects, both at central and peripheral levels, have been well documented and characterized. However, numerous evidences demonstrated that these pharmacological actions could not be attributable solely to the activation of CB1 and CB2 receptors since several important cannabimimetic actions have been found in biological systems lacking CB1 or CB2 gene such as in specific cell lines or transgenic mice. It is now well accepted that, beyond their receptor-mediated effects, these molecules can act also via CB1/CB2-receptor-independent mechanism. Cannabinoids have been demonstrated to modulate several voltage-gated channels (including Ca2+, Na+, and various type of K+ channels), ligand-gated ion channels (i.e., GABA, glycine), and ion-transporting membranes proteins such as transient potential receptor class (TRP) channels. The first direct, cannabinoid receptor-independent interaction was reported on the function of serotonin 5-HT3 receptor-ion channel complex. Similar effects were reported also on the other above mentioned ion channels. In the early ninety, studies searching for endogenous modulators of L-type Ca2+ channels identified anandamide as ligand for L-type Ca2+ channel. Later investigations indicated that other types of Ca2+ currents are also affected by endocannabinoids, and, in the late ninety, it was discovered that endocannabinoids activate the vanilloid receptor subtype 1 (TRPV1), and nowadays, it is known that (endo)cannabinoids gate at least five distinct TRP channels. This chapter focuses on cannabinoid regulation of ion channels and lays special emphasis on their action at transient receptor channels.
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Furukawa C, Fujii N, Manabe A, Matsunaga T, Endo S, Hasegawa H, Ito Y, Yamaguchi M, Yamazaki Y, Ikari A. Up-Regulation of Transient Receptor Potential Melastatin 6 Channel Expression by Tumor Necrosis Factor-α in the Presence of Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor. J Cell Physiol 2017; 232:2841-2850. [DOI: 10.1002/jcp.25709] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Accepted: 12/01/2016] [Indexed: 01/22/2023]
Affiliation(s)
- Chisa Furukawa
- Laboratory of Biochemistry; Department of Biopharmaceutical Sciences; Gifu Pharmaceutical University; Gifu Japan
| | - Naoko Fujii
- Laboratory of Biochemistry; Department of Biopharmaceutical Sciences; Gifu Pharmaceutical University; Gifu Japan
| | - Aya Manabe
- Laboratory of Biochemistry; Department of Biopharmaceutical Sciences; Gifu Pharmaceutical University; Gifu Japan
| | - Toshiyuki Matsunaga
- Laboratory of Biochemistry; Department of Biopharmaceutical Sciences; Gifu Pharmaceutical University; Gifu Japan
| | - Satoshi Endo
- Laboratory of Biochemistry; Department of Biopharmaceutical Sciences; Gifu Pharmaceutical University; Gifu Japan
| | - Hajime Hasegawa
- Saitama Medical Center; Saitama Medical University; Saitama Japan
| | - Yoshinori Ito
- Department of Pharmacy; Gifu University Hospital; Gifu Japan
| | - Masahiko Yamaguchi
- School of Pharmaceutical Sciences; University of Shizuoka; Shizuoka Japan
| | - Yasuhiro Yamazaki
- School of Pharmaceutical Sciences; University of Shizuoka; Shizuoka Japan
| | - Akira Ikari
- Laboratory of Biochemistry; Department of Biopharmaceutical Sciences; Gifu Pharmaceutical University; Gifu Japan
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Suzuki Y, Watanabe M, Saito CT, Tominaga M. Expression of the TRPM6 in mouse placental trophoblasts; potential role in maternal-fetal calcium transport. J Physiol Sci 2017; 67:151-162. [PMID: 27043350 PMCID: PMC10717052 DOI: 10.1007/s12576-016-0449-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 03/20/2016] [Indexed: 12/14/2022]
Abstract
The placenta is required to transport calcium (Ca2+) from mother to fetus during fetal bone mineralization. In an attempt to clarify the molecular basis of Ca2+ entry for this transport, we identified TRPM6 as a candidate for apical Ca2+ entry pathway. TRPM6 mRNA increased during the last 4 days of pregnancy, coinciding with fetal bone mineralization in mice. TRPM6 mRNA and protein was localized in the trophoblasts in labyrinth where the maternal-fetal Ca2+ transport occurs. In patch-clamp recordings, we observed TRPM6/TRPM7-like currents in mouse trophoblasts after starting fetal bone mineralization but not before mineralization. Plasma membrane Ca2+ permeability was significantly increased in TRPM6/TRPM7 expressed HEK293 cells under physiological Mg2+ and ATP concentration but not in TRPM6 or TRPM7 homomer-expressing cells. These results suggest that TRPM6 is functionally expressed in mouse placental trophoblasts, implicating in maternal-fetal Ca2+ transport likely with TRPM7, which might enable to sustain fetal bone mineralization.
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Affiliation(s)
- Yoshiro Suzuki
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki, 444-8787, Japan.
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan.
| | - Masaki Watanabe
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki, 444-8787, Japan
- Department of Renal and Urologic Surgery, Asahikawa Medical University, Asahikawa, 078-8510, Japan
| | - Claire T Saito
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki, 444-8787, Japan
| | - Makoto Tominaga
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki, 444-8787, Japan.
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan.
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Chubanov V, Ferioli S, Wisnowsky A, Simmons DG, Leitzinger C, Einer C, Jonas W, Shymkiv Y, Bartsch H, Braun A, Akdogan B, Mittermeier L, Sytik L, Torben F, Jurinovic V, van der Vorst EPC, Weber C, Yildirim ÖA, Sotlar K, Schürmann A, Zierler S, Zischka H, Ryazanov AG, Gudermann T. Epithelial magnesium transport by TRPM6 is essential for prenatal development and adult survival. eLife 2016; 5:e20914. [PMID: 27991852 PMCID: PMC5218537 DOI: 10.7554/elife.20914] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 12/13/2016] [Indexed: 12/21/2022] Open
Abstract
Mg2+ regulates many physiological processes and signalling pathways. However, little is known about the mechanisms underlying the organismal balance of Mg2+. Capitalizing on a set of newly generated mouse models, we provide an integrated mechanistic model of the regulation of organismal Mg2+ balance during prenatal development and in adult mice by the ion channel TRPM6. We show that TRPM6 activity in the placenta and yolk sac is essential for embryonic development. In adult mice, TRPM6 is required in the intestine to maintain organismal Mg2+ balance, but is dispensable in the kidney. Trpm6 inactivation in adult mice leads to a shortened lifespan, growth deficit and metabolic alterations indicative of impaired energy balance. Dietary Mg2+ supplementation not only rescues all phenotypes displayed by Trpm6-deficient adult mice, but also may extend the lifespan of wildtype mice. Hence, maintenance of organismal Mg2+ balance by TRPM6 is crucial for prenatal development and survival to adulthood.
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Affiliation(s)
- Vladimir Chubanov
- Walther-Straub Institute of Pharmacology and Toxicology, Ludwig Maximilian University of Munich, Munich, Germany
- (VC)
| | - Silvia Ferioli
- Walther-Straub Institute of Pharmacology and Toxicology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Annika Wisnowsky
- Walther-Straub Institute of Pharmacology and Toxicology, Ludwig Maximilian University of Munich, Munich, Germany
| | - David G Simmons
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
| | - Christin Leitzinger
- Institute of Molecular Toxicology and Pharmacology, Helmholtz Zentrum Munich, Neuherberg, Germany
| | - Claudia Einer
- Institute of Molecular Toxicology and Pharmacology, Helmholtz Zentrum Munich, Neuherberg, Germany
| | - Wenke Jonas
- Department of Experimental Diabetology, German Institute of Human Nutrition, Potsdam-Rehbruecke, Germany
- German Center for Diabetes Research, Munich, Germany
| | - Yuriy Shymkiv
- Princeton Institute of Life Sciences, Princeton, United States
| | - Harald Bartsch
- Institute of Pathology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Attila Braun
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
- Department of Vascular Medicine, University Hospital Würzburg, Würzburg, Germany
| | - Banu Akdogan
- Walther-Straub Institute of Pharmacology and Toxicology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Lorenz Mittermeier
- Walther-Straub Institute of Pharmacology and Toxicology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Ludmila Sytik
- Walther-Straub Institute of Pharmacology and Toxicology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Friedrich Torben
- Genome Analysis Center, Institute of Experimental Genetics, Helmholtz Zentrum Munich, Neuherberg, Germany
| | - Vindi Jurinovic
- Institute for Medical Informatics, Biometry and Epidemiology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Emiel PC van der Vorst
- Institute for Cardiovascular Prevention, Ludwig Maximilian University of Munich, Munich, Germany
| | - Christian Weber
- Institute for Cardiovascular Prevention, Ludwig Maximilian University of Munich, Munich, Germany
- German Centre for Cardiovascular Research, Munich Heart Alliance, Munich, Germany
| | - Önder A Yildirim
- Comprehensive Pneumology Center, Institute of Lung Biology and Disease, Helmholtz Zentrum Munich, Neuherberg, Germany
- German Center for Lung Research, Munich, Germany
| | - Karl Sotlar
- Institute of Pathology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Annette Schürmann
- Department of Experimental Diabetology, German Institute of Human Nutrition, Potsdam-Rehbruecke, Germany
- German Center for Diabetes Research, Munich, Germany
| | - Susanna Zierler
- Walther-Straub Institute of Pharmacology and Toxicology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Hans Zischka
- Institute of Molecular Toxicology and Pharmacology, Helmholtz Zentrum Munich, Neuherberg, Germany
| | - Alexey G Ryazanov
- Princeton Institute of Life Sciences, Princeton, United States
- Department of Cellular and Molecular Pharmacology, Rutgers Robert Wood Johnson Medical School, Piscataway, United States
| | - Thomas Gudermann
- Walther-Straub Institute of Pharmacology and Toxicology, Ludwig Maximilian University of Munich, Munich, Germany
- German Centre for Cardiovascular Research, Munich Heart Alliance, Munich, Germany
- Comprehensive Pneumology Center Munich, German Center for Lung Research, Munich, Germany
- (TG)
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Saraç M, Önalan E, Bakal Ü, Tartar T, Aydın M, Orman A, Tektemur A, Taşkın E, Erol FS, Kazez A. Magnesium-permeable TRPM6 polymorphisms in patients with meningomyelocele. SPRINGERPLUS 2016; 5:1703. [PMID: 27757375 PMCID: PMC5047867 DOI: 10.1186/s40064-016-3395-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 09/26/2016] [Indexed: 11/10/2022]
Abstract
BACKGROUND To evaluate whether there is an association between single nucleotide polymorphisms in magnesium-permeable TRPM6 ion channel and development of meningomyelocele (MMC). Therefore, we examined a total of 150 children with MMC, along with age- and gender-matched controls. DNA collected from whole blood was analyzed for the presence of two polymorphisms, rs2274924 (A > G; K1579E; Leu1579Glu) and rs3750425 (G > A; Val1393Ile), in TRPM6. Serum Mg2+ and calcium levels were also examined. RESULTS A statistically significant difference in the distribution of rs2274924 genotypes (p = 0.049) was observed between the groups. Decreases in the AA genotype, and increases in the AG heterozygous genotype were also detected in the study group. The distribution of polymorphisms in the rs3750425 genotype and alleles was not statistically different between groups. Serum Mg2+ levels were lower in the GG genotype of rs3750425 compared with the GA and AA genotypes (p = 0.003). CONCLUSIONS A statistically significant difference in rs3750425 genotypes was observed between the patients with MMC and the controls, which corresponded to lower serum Mg2+ concentrations in these patients. Taken together, these results suggest that genetic variations in the Mg2+-permeable TRPM6 ion channel may play a role in the etiopathogenesis of MMC during embryonic development.
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Affiliation(s)
- Mehmet Saraç
- Department of Pediatric Surgery, Firat University Medical Faculty, 23119 Elazig, Turkey
| | - Ebru Önalan
- Department of Medical Biology, Firat University Medical Faculty, Elazig, Turkey
| | - Ünal Bakal
- Department of Pediatric Surgery, Firat University Medical Faculty, 23119 Elazig, Turkey
| | - Tugay Tartar
- Department of Pediatric Surgery, Firat University Medical Faculty, 23119 Elazig, Turkey
| | - Mustafa Aydın
- Department of Neonatology, Firat University Medical Faculty, Elazig, Turkey
| | - Ayşen Orman
- Department of Neonatology, Firat University Medical Faculty, Elazig, Turkey
| | - Ahmet Tektemur
- Department of Medical Biology, Firat University Medical Faculty, Elazig, Turkey
| | - Erdal Taşkın
- Department of Neonatology, Firat University Medical Faculty, Elazig, Turkey
| | - Fatih Serhat Erol
- Department of Neurosurgery, Firat University Medical Faculty, Elazig, Turkey
| | - Ahmet Kazez
- Department of Pediatric Surgery, Firat University Medical Faculty, 23119 Elazig, Turkey
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Vrenken KS, Jalink K, van Leeuwen FN, Middelbeek J. Beyond ion-conduction: Channel-dependent and -independent roles of TRP channels during development and tissue homeostasis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:1436-46. [DOI: 10.1016/j.bbamcr.2015.11.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 10/26/2015] [Accepted: 11/11/2015] [Indexed: 01/09/2023]
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Wang GQ, Qin JC, Fan L, Li CR, Yang ZY. A turn-on fluorescent sensor for highly selective recognition of Mg2+ based on new Schiff’s base derivative. J Photochem Photobiol A Chem 2016. [DOI: 10.1016/j.jphotochem.2015.08.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Astor MC, Løvås K, Wolff ASB, Nedrebø B, Bratland E, Steen-Johnsen J, Husebye ES. Hypomagnesemia and functional hypoparathyroidism due to novel mutations in the Mg-channel TRPM6. Endocr Connect 2015; 4:215-22. [PMID: 26273099 PMCID: PMC4566842 DOI: 10.1530/ec-15-0066] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Accepted: 08/13/2015] [Indexed: 11/26/2022]
Abstract
Primary hypomagnesemia with secondary hypocalcemia (HSH) is an autosomal recessive disorder characterized by neuromuscular symptoms in infancy due to extremely low levels of serum magnesium and moderate to severe hypocalcemia. Homozygous mutations in the magnesium transporter gene transient receptor potential cation channel member 6 (TRPM6) cause the disease. HSH can be misdiagnosed as primary hypoparathyroidism. The aim of this study was to describe the genetic, clinical and biochemical features of patients clinically diagnosed with HSH in a Norwegian cohort. Five patients in four families with clinical features of HSH were identified, including one during a national survey of hypoparathyroidism. The clinical history of the patients and their families were reviewed and gene analyses of TRPM6 performed. Four of five patients presented with generalized seizures in infancy and extremely low levels of serum magnesium accompanied by moderate hypocalcemia. Two of the patients had an older sibling who died in infancy. Four novel mutations and one large deletion in TRPM6 were identified. In one patient two linked homozygous mutations were located in exon 22 (p.F978L) and exon 23 (p.G1042V). Two families had an identical mutation in exon 25 (p.E1155X). The fourth patient had a missense mutation in exon 4 (p.H61N) combined with a large deletion in the C-terminal end of the gene. HSH is a potentially lethal condition that can be misdiagnosed as primary hypoparathyroidism. The diagnosis is easily made if serum magnesium is measured. When treated appropriately with high doses of oral magnesium supplementation, severe hypomagnesemia is uncommon and the long-term prognosis seems to be good.
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Affiliation(s)
- Marianne C Astor
- Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway
| | - Kristian Løvås
- Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway
| | - Anette S B Wolff
- Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway
| | - Bjørn Nedrebø
- Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway
| | - Eirik Bratland
- Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway
| | - Jon Steen-Johnsen
- Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway
| | - Eystein S Husebye
- Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway
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Geng Y, Feng B. Mesendogen, a novel inhibitor of TRPM6, promotes mesoderm and definitive endoderm differentiation of human embryonic stem cells through alteration of magnesium homeostasis. Heliyon 2015; 1:e00046. [PMID: 26705539 PMCID: PMC4685751 DOI: 10.1016/j.heliyon.2015.e00046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The homo- and hetero-tetrameric channel complexes formed by transient receptor potential cation channel, subfamily M, member 6 (TRPM6) and 7 (TRPM7) (collectively referred to as TRPM6/TRPM7 channels in this study) are the major regulators of cellular magnesium uptake, yet the exact roles of TRPM6/TRPM7 channels and cellular magnesium homeostasis during development are poorly understood. Here, we report a novel small molecule Mesendogen (MEG) which robustly induces nearly homogeneous (≥85%) mesoderm and definitive endoderm (DE) differentiations of human embryonic stem cells (hESCs) in combination with growth factors. A kinome screen followed by loss-of-function experiments identified TRPM6 as the biological target of MEG. We demonstrated that MEG functions by inhibiting TRPM6/TRPM7 magnesium channel activity, as MEG reduced intracellular magnesium level, while TRPM6/TRPM7 channel modulation and magnesium-withdrawal phenocopied MEG at enhancing mesoderm and DE differentiations. This study discovers a robust chemical enhancer of hESC directed differentiation, and uncovers a novel regulatory role of cellular magnesium homeostasis during early embryonic cell fate specification.
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Affiliation(s)
- Yijie Geng
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Bradley Feng
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Blanchard MG, Kittikulsuth W, Nair AV, de Baaij JHF, Latta F, Genzen JR, Kohan DE, Bindels RJM, Hoenderop JGJ. Regulation of Mg2+ Reabsorption and Transient Receptor Potential Melastatin Type 6 Activity by cAMP Signaling. J Am Soc Nephrol 2015; 27:804-13. [PMID: 26150606 DOI: 10.1681/asn.2014121228] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 05/21/2015] [Indexed: 01/14/2023] Open
Abstract
The transient receptor potential melastatin type 6 (TRPM6) epithelial Mg(2+) channels participate in transcellular Mg(2+) transport in the kidney and intestine. Previous reports suggested a hormonal cAMP-dependent regulation of Mg(2+) reabsorption in the kidney. The molecular details of this process are, however, unknown. Adenylate cyclase 3 (Adcy3) has been shown to colocalize with the Na(+)/Cl(-) cotransporter, a marker of the distal convoluted segment of the kidney, the principal site of TRPM6 expression. Given the critical role of TRPM6 in Mg(2+) reabsorption, an inducible kidney-specific Adcy3 deletion mouse model was characterized for blood and urinary electrolyte disturbances under a normal--and low--Mg(2+) diet. Increased urinary Mg(2+) wasting and Trpm6 mRNA levels were observed in the urine and kidney of Adcy3-deleted animals compared with wild-type controls. Serum Mg(2+) concentration was significantly lower in Adcy3-deleted animals at day 7 on the low Mg(2+) diet. Using patch clamp electrophysiology, cell surface biotinylation, and total internal reflection fluorescence live cell imaging of transfected HEK293 cells, we demonstrated that cAMP signaling rapidly potentiates TRPM6 activity by promoting TRPM6 accumulation at the plasma membrane and increasing its single-channel conductance. Comparison of electrophysiological data from cells expressing the phosphorylation-deficient S1252A or phosphomimetic S1252D TRPM6 mutants suggests that phosphorylation at this intracellular residue participates in the observed stimulation of channel activity. Altogether, these data support a physiologically relevant magnesiotropic role of cAMP signaling in the kidney by a direct stimulatory action of protein kinase A on the plasma membrane trafficking and function of TRPM6 ion channels.
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Affiliation(s)
- Maxime G Blanchard
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | - Anil V Nair
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands; Center for Systems Biology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Jeroen H F de Baaij
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Femke Latta
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jonathan R Genzen
- Department of Pathology, School of Medicine, University of Utah, Salt Lake City, Utah; and
| | | | - René J M Bindels
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joost G J Hoenderop
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands;
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Katayama K, Povalko N, Yatsuga S, Nishioka J, Kakuma T, Matsuishi T, Koga Y. New TRPM6 mutation and management of hypomagnesaemia with secondary hypocalcaemia. Brain Dev 2015; 37:292-8. [PMID: 24985022 DOI: 10.1016/j.braindev.2014.06.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 06/04/2014] [Accepted: 06/06/2014] [Indexed: 11/25/2022]
Abstract
BACKGROUND TRPM6 gene mutation has been reported to cause hypomagnesemia with secondary hypocalcemia (HSH). However, the genotype-phenotype correlation for TRPM6 gene mutations has not been clarified. OBJECTIVE To elucidate the factors underlying the severe neurological complications in HSH and evaluate the potential association between the location of TRPM6 gene mutations and clinical data of HSH. METHODS A Japanese patient diagnosed with HSH at 10 weeks of age exhibited neurological damage and failed to thrive. Magnesium supplements were therefore started at 12 weeks of age. Mutational analysis of the TRPM6 gene was performed using a direct sequencing method to determine the position and type of mutation. Using the data of 29 HSH patients reported in the literature, linear regression analysis was also performed to examine the association between TRPM6 gene mutation location and HSH onset age, initial serum magnesium and calcium concentrations, and dose of oral magnesium. RESULTS A novel stop-codon homozygous mutation [c.4190 G>A] W1397X was identified in exon 26 of the patient's TRPM6 gene. No statistical correlation was found between the location of mutations in the TRPM6 gene and the clinical data for 4 clinical indicators of HSH. CONCLUSIONS We identified the first Japanese HSH patient with a novel nonsense mutation in the TRPM6 gene. Regression analysis of mutation locations in the protein-coding region of TRPM6 and the reported clinical data for 4 clinical indicators of HSH in 30 HSH patients did not detect a genotype-phenotype correlation.
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Affiliation(s)
- Koujyu Katayama
- Department of Pediatrics and Child Health, Kurume University Graduate School of Medicine, Kurume, Japan
| | - Nataliya Povalko
- Department of Pediatrics and Child Health, Kurume University Graduate School of Medicine, Kurume, Japan
| | - Shuichi Yatsuga
- Department of Pediatrics and Child Health, Kurume University Graduate School of Medicine, Kurume, Japan
| | - Junko Nishioka
- Department of Pediatrics and Child Health, Kurume University Graduate School of Medicine, Kurume, Japan
| | - Tatsuyuki Kakuma
- Department of Biostatistics, Kurume University Graduate School of Medicine, Kurume, Japan
| | - Toyojiro Matsuishi
- Department of Pediatrics and Child Health, Kurume University Graduate School of Medicine, Kurume, Japan
| | - Yasutoshi Koga
- Department of Pediatrics and Child Health, Kurume University Graduate School of Medicine, Kurume, Japan.
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Abstract
PURPOSE OF REVIEW The tight control of blood magnesium (Mg) levels is of central importance for numerous physiological processes. A persistent low Mg status (hypomagnesemia) is associated with severe health risks and is involved in the pathogenesis of type 2 diabetes mellitus, osteoporosis, asthma, and heart and vascular diseases. The current view has expanded significantly as a result of the identification of novel genes and regulatory pathways involved in hypomagnesemic disorders. This review aims to give an up-to-date overview of transient receptor potential melastatin 6 (TRPM6) regulation and its role in the maintenance of Mg homeostasis. RECENT FINDINGS The epithelial Mg channel TRPM6 is considered to be the Mg entry pathway in the distal convoluted tubule of the kidney, where it functions as gatekeeper for controlling the body's Mg balance. Various factors and hormones contribute not only to the function, but also to the dysregulation of TRPM6, which has a substantial impact on renal Mg handling. Recent genetic and molecular studies have further elucidated the signaling processes of epithelial Mg transport, including their effect on the expression and function of TRPM6. SUMMARY Knowledge of TRPM6 functioning is of vital importance to decipher its role in Mg handling and will, in particular, provide a molecular basis for achieving a better understanding of Mg mal(re)absorption and hence systemic Mg balance.
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Differential mRNA expression and glucocorticoid-mediated regulation of TRPM6 and TRPM7 in the heart and kidney throughout murine pregnancy and development. PLoS One 2015; 10:e0117978. [PMID: 25692682 PMCID: PMC4333289 DOI: 10.1371/journal.pone.0117978] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 01/06/2015] [Indexed: 11/19/2022] Open
Abstract
The transient receptor potential (TRP) channels TRPM6 and TRPM7 are critically involved in maintaining whole body and cellular Mg2+ homeostasis and ensuring the normal function of organs such as the heart and kidney. However, we do not know how the expression of TRPM6 and TPRM7 in these organs changes throughout fetal development and adult life, and whether this expression can be hormonally regulated. This study determined the ontogeny of TRPM6 and TRPM7 mRNA expression from mid-gestation through to adulthood in the mouse. In a second series of experiments, we examined how maternal administration of the glucocorticoids corticosterone and dexamethasone between embryonic days 12.5–15 affected TRPM6 and TRPM7 channel mRNA expression in the mother and fetus. Whilst renal TRPM7 expression was relatively constant throughout development, renal TRPM6 expression was markedly upregulated after birth. In contrast, cardiac TRPM7 expression was 2–4 fold higher in the fetus than in the adult. Surprisingly, TRPM6 expression was detected in the fetal heart (qPCR and in situ hybridization). Glucocorticoid administration during gestation increased fetal cardiac expression of both channels without affecting renal expression. In contrast, in the dam renal TRPM6 and TRPM7 expression was increased by glucocorticoids with no change in the cardiac channel expression. These data suggest that TRPM6 and TRPM7 channels are important in organogenesis, and that elevated maternal glucocorticoid levels can alter the expression of these channels. This suggests that perturbations in hormonal regulatory systems during pregnancy may adversely impact upon normal fetal development, at least in part by altering expression of TRPM channels.
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Daglar K, Tokmak A, Kirbas A, Guzel AI, Erkenekli K, Yucel A, Uygur D. Maternal serum vitamin D levels in pregnancies complicated by neural tube defects. J Matern Fetal Neonatal Med 2014; 29:298-302. [DOI: 10.3109/14767058.2014.999037] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Korkut Daglar
- Dr. Zekai Tahir Burak Women’s Health Research and Education Hospital, Ankara, Turkey
| | - Aytekin Tokmak
- Dr. Zekai Tahir Burak Women’s Health Research and Education Hospital, Ankara, Turkey
| | - Ayse Kirbas
- Dr. Zekai Tahir Burak Women’s Health Research and Education Hospital, Ankara, Turkey
| | - Ali Irfan Guzel
- Dr. Zekai Tahir Burak Women’s Health Research and Education Hospital, Ankara, Turkey
| | - Kudret Erkenekli
- Dr. Zekai Tahir Burak Women’s Health Research and Education Hospital, Ankara, Turkey
| | - Aykan Yucel
- Dr. Zekai Tahir Burak Women’s Health Research and Education Hospital, Ankara, Turkey
| | - Dilek Uygur
- Dr. Zekai Tahir Burak Women’s Health Research and Education Hospital, Ankara, Turkey
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Abstract
Transient Receptor Potential (TRP) channels are activated by stimuli as diverse as heat, cold, noxious chemicals, mechanical forces, hormones, neurotransmitters, spices, and voltage. Besides their presumably similar general architecture, probably the only common factor regulating them is phosphoinositides. The regulation of TRP channels by phosphoinositides is complex. There are a large number of TRP channels where phosphatidylinositol 4,5 bisphosphate [PI(4,5)P2 or PIP2] acts as a positive cofactor, similarly to many other ion channels. In several cases, however, PI(4,5)P2 inhibits TRP channel activity, sometimes even concurrently with the activating effect. This chapter will provide a comprehensive overview of the literature on regulation of TRP channels by membrane phosphoinositides.
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Kinase and channel activity of TRPM6 are co-ordinated by a dimerization motif and pocket interaction. Biochem J 2014; 460:165-75. [PMID: 24650431 PMCID: PMC4019984 DOI: 10.1042/bj20131639] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mutations in the gene that encodes the atypical channel-kinase TRPM6 (transient receptor potential melastatin 6) cause HSH (hypomagnesaemia with secondary hypocalcaemia), a disorder characterized by defective intestinal Mg2+ transport and impaired renal Mg2+ reabsorption. TRPM6, together with its homologue TRPM7, are unique proteins as they combine an ion channel domain with a C-terminally fused protein kinase domain. How TRPM6 channel and kinase activity are linked is unknown. Previous structural analysis revealed that TRPM7 possesses a non-catalytic dimerization motif preceding the kinase domain. This interacts with a dimerization pocket lying within the kinase domain. In the present study, we provide evidence that the dimerization motif in TRPM6 plays a critical role in regulating kinase activity as well as ion channel activity. We identify mutations within the TRPM6 dimerization motif (Leu1718 and Leu1721) or dimerization pocket (L1743A, Q1832K, A1836N, L1840A and L1919Q) that abolish dimerization and establish that these mutations inhibit protein kinase activity. We also demonstrate that kinase activity of a dimerization motif mutant can be restored by addition of a peptide encompassing the dimerization motif. Moreover, we observe that mutations that disrupt the dimerization motif and dimerization pocket interaction greatly diminish TRPM6 ion channel activity, in a manner that is independent of kinase activity. Finally, we analyse the impact on kinase activity of ten disease-causing missense mutations that lie outwith the protein kinase domain of TRPM6. This revealed that one mutation lying nearby the dimerization motif (S1754N), found previously to inhibit channel activity, abolished kinase activity. These results provide the first evidence that there is structural co-ordination between channel and kinase activity, which is mediated by the dimerization motif and pocket interaction. We discuss that modulation of this interaction could comprise a major regulatory mechanism by which TRPM6 function is controlled. We show that TRPM6 kinase activity is linked to channel activity. This occurs through a kinase-independent mechanism involving the dimerization motif binding to a pocket within the kinase domain. A disease-causing mutation (S1754N) lying nearby the dimerization pocket inactivates kinase activity.
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Abstract
The epithelium of the gastrointestinal tract is one of the most versatile tissues in the organism, responsible for providing a tight barrier between dietary and bacterial antigens and the mucosal and systemic immune system while maintaining efficient digestive and absorptive processes to ensure adequate nutrient and energy supply. Inflammatory bowel diseases (Crohn's disease and ulcerative colitis) are associated with a breakdown of both functions, which in some cases are clearly interrelated. In this updated literature review, we focus on the effects of intestinal inflammation and the associated immune mediators on selected aspects of the transepithelial transport of macronutrients and micronutrients. The mechanisms responsible for nutritional deficiencies are not always clear and could be related to decreased intake, malabsorption, and excess losses. We summarize the known causes of nutrient deficiencies and the mechanism of inflammatory bowel disease-associated diarrhea. We also overview the consequences of impaired epithelial transport, which infrequently transcend its primary purpose to affect the gut microbial ecology and epithelial integrity. Although some of those regulatory mechanisms are relatively well established, more work needs to be done to determine how inflammatory cytokines can alter the transport process of nutrients across the gastrointestinal and renal epithelia.
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Brandao K, Deason-Towne F, Zhao X, Perraud AL, Schmitz C. TRPM6 kinase activity regulates TRPM7 trafficking and inhibits cellular growth under hypomagnesic conditions. Cell Mol Life Sci 2014; 71:4853-67. [PMID: 24858416 DOI: 10.1007/s00018-014-1647-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 04/14/2014] [Accepted: 05/05/2014] [Indexed: 11/29/2022]
Abstract
The channel kinases TRPM6 and TRPM7 are both members of the melastatin-related transient receptor potential (TRPM) subfamily of ion channels and the only known fusions of an ion channel pore with a kinase domain. TRPM6 and TRPM7 form functional, tetrameric channel complexes at the plasma membrane by heteromerization. TRPM6 was previously shown to cross-phosphorylate TRPM7 on threonine residues, but not vice versa. Genetic studies demonstrated that TRPM6 and TRPM7 fulfill non-redundant functions and that each channel contributes uniquely to the regulation of Mg(2+) homeostasis. Although there are indications that TRPM6 and TRPM7 can influence each other's cellular distribution and activity, little is known about the functional relationship between these two channel-kinases. In the present study, we examined how TRPM6 kinase activity influences TRPM7 serine phosphorylation, intracellular trafficking, and cell surface expression of TRPM7, as well as Mg(2+)-dependent cellular growth. We found TRPM7 serine phosphorylation via the TRPM6 kinase, but no TRPM6 serine phosphorylation via the TRPM7 kinase. Intracellular trafficking of TRPM7 was altered in HEK-293 epithelial kidney cells and DT40 B cells in the presence of TRPM6 with intact kinase activity, independently of the availability of extracellular Mg(2+), but TRPM6/7 surface labeling experiments indicate comparable levels of the TRPM6/7 channels at the plasma membrane. Furthermore, using a complementation approach in TRPM7-deficient DT40 B-cells, we demonstrated that wild-type TRPM6 inhibited cell growth under hypomagnesic cell culture conditions in cells co-expressing TRPM6 and TRPM7; however, co-expression of a TRPM6 kinase dead mutant had no effect-a similar phenotype was also observed in TRPM6/7 co-expressing HEK-293 cells. Our results provide first clues about how heteromer formation between TRPM6 and TRPM7 influences the biological activity of these ion channels. We show that TRPM6 regulates TRPM7 intracellular trafficking and TRPM7-dependent cell growth. All these effects are dependent upon the presence of an active TRPM6 kinase domain. Dysregulated Mg(2+)-homeostasis causes or exacerbates many pathologies. As TRPM6 and TRPM7 are expressed simultaneously in numerous cell types, understanding how their relationship impacts regulation of Mg(2+)-uptake is thus important knowledge.
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Affiliation(s)
- Katherine Brandao
- Integrated Department of Immunology, University of Colorado School of Medicine, 1400 Jackson Street, Denver, CO, 80206, USA
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Abstract
Important for energy metabolism, neurotransmission, bone stability, and other cellular functions, Mg(2+) has well-established and undisputedly critical roles in adult tissues. Its contributions to early embryonic development are less clearly understood. For decades it has been known that gestational Mg(2+) deficiency in rodents produces teratogenic effects. More recent studies have linked deficiency in this vital cation to birth defects in humans, including spina bifida, a neural fold closure defect in humans that occurs at an average rate of 1 per 1000 pregnancies. The first suggestion that Mg(2+) may be playing a more specific role in early development arose from studies of the TRPM7 and TRPM6 ion channels. TRPM7 and TRPM6 are divalent-selective ion channels in possession of their own kinase domains that have been implicated in the control of Mg(2+) homeostasis in vertebrates. Disruption of the functions of these ion channels in mice as well as in frogs interferes with gastrulation, a pivotal process during early embryonic development that executes the emergence of the body plan and closure of the neural tube. Surprisingly, gastrulation defects produced by depletion of TRPM7 can be prevented by Mg(2+) supplementation, indicating an essential role for Mg(2+) in gastrulation and neural fold closure. The aim of this review is to summarize the data emerging from molecular genetic, biochemical and electrophysiological studies of TRPM6 and TRPM7 and provide a model of how Mg(2+), through these unique channel-kinases, may be impacting early embryonic development.
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Affiliation(s)
- Yuko Komiya
- Department of Pharmacology, Rutgers Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA
| | - Li-Ting Su
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Hsiang-Chin Chen
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Raymond Habas
- Department of Biology, College of Science and Technology, Temple University, 1900 North 12 Street, Philadelphia, PA 19122, USA
| | - Loren W. Runnels
- Department of Pharmacology, Rutgers Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA
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50
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Abstract
TRPM6 is a bifunctional protein comprising a TRP cation channel segment covalently linked to an α-type serine/threonine protein kinase. TRPM6 is expressed in the intestinal and renal epithelial cells. Loss-of-function mutations in the human TRPM6 gene give rise to hypomagnesemia with secondary hypocalcemia (HSH), suggesting that the TRPM6 channel kinase plays a central role in systemic Mg(2+) homeostasis. In contrast, Trpm6 null mice show a delay in prenatal development, neural tube defects, and prenatal death. Possible functions of TRPM6 in prenatal and adult organisms will be discussed in this chapter.
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Affiliation(s)
- Vladimir Chubanov
- Walther-Straub-Institute for Pharmacology and Toxicology, Ludwig-Maximilians University Munich, Goethestrasse 33, Munich, 80336, Germany,
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