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Yelshanskaya MV, Sobolevsky AI. Ligand-Binding Sites in Vanilloid-Subtype TRP Channels. Front Pharmacol 2022; 13:900623. [PMID: 35652046 PMCID: PMC9149226 DOI: 10.3389/fphar.2022.900623] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 04/06/2022] [Indexed: 02/02/2023] Open
Abstract
Vanilloid-subfamily TRP channels TRPV1-6 play important roles in various physiological processes and are implicated in numerous human diseases. Advances in structural biology, particularly the "resolution revolution" in cryo-EM, have led to breakthroughs in molecular characterization of TRPV channels. Structures with continuously improving resolution uncover atomic details of TRPV channel interactions with small molecules and protein-binding partners. Here, we provide a classification of structurally characterized binding sites in TRPV channels and discuss the progress that has been made by structural biology combined with mutagenesis, functional recordings, and molecular dynamics simulations toward understanding of the molecular mechanisms of ligand action. Given the similarity in structural architecture of TRP channels, 16 unique sites identified in TRPV channels may be shared between TRP channel subfamilies, although the chemical identity of a particular ligand will likely depend on the local amino-acid composition. The characterized binding sites and molecular mechanisms of ligand action create a diversity of druggable targets to aid in the design of new molecules for tuning TRP channel function in disease conditions.
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Affiliation(s)
| | - Alexander I. Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, United States
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2
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Khattar V, Wang L, Peng JB. Calcium selective channel TRPV6: Structure, function, and implications in health and disease. Gene 2022; 817:146192. [PMID: 35031425 PMCID: PMC8950124 DOI: 10.1016/j.gene.2022.146192] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 12/20/2021] [Accepted: 01/07/2022] [Indexed: 12/14/2022]
Abstract
Calcium-selective channel TRPV6 (Transient Receptor Potential channel family, Vanilloid subfamily member 6) belongs to the TRP family of cation channels and plays critical roles in transcellular calcium (Ca2+) transport, reuptake of Ca2+ into cells, and maintaining a local low Ca2+ environment for certain biological processes. Recent crystal and cryo-electron microscopy-based structures of TRPV6 have revealed mechanistic insights on how the protein achieves Ca2+ selectivity, permeation, and inactivation by calmodulin. The TRPV6 protein is expressed in a range of epithelial tissues such as the intestine, kidney, placenta, epididymis, and exocrine glands such as the pancreas, prostate and salivary, sweat, and mammary glands. The TRPV6 gene is a direct transcriptional target of the active form of vitamin D and is efficiently regulated to meet the body's need for Ca2+ demand. In addition, TRPV6 is also regulated by the level of dietary Ca2+ and under physiological conditions such as pregnancy and lactation. Genetic models of loss of function in TRPV6 display hypercalciuria, decreased bone marrow density, deficient weight gain, reduced fertility, and in some cases alopecia. The models also reveal that the channel plays an indispensable role in maintaining maternal-fetal Ca2+ transport and low Ca2+ environment in the epididymal lumen that is critical for male fertility. Most recently, loss of function mutations in TRPV6 gene is linked to transient neonatal hyperparathyroidism and early onset chronic pancreatitis. TRPV6 is overexpressed in a wide range of human malignancies and its upregulation is strongly correlated to tumor aggressiveness, metastasis, and poor survival in selected cancers. This review summarizes the current state of knowledge on the expression, structure, biophysical properties, function, polymorphisms, and regulation of TRPV6. The aberrant expression, polymorphisms, and dysfunction of this protein linked to human diseases are also discussed.
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Affiliation(s)
- Vinayak Khattar
- Division of Nephrology, Department of Medicine, Nephrology Research and Training Center, Department of Urology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Lingyun Wang
- Division of Nephrology, Department of Medicine, Nephrology Research and Training Center, Department of Urology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Ji-Bin Peng
- Division of Nephrology, Department of Medicine, Nephrology Research and Training Center, Department of Urology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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3
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Neuberger A, Nadezhdin KD, Sobolevsky AI. Structural mechanisms of TRPV6 inhibition by ruthenium red and econazole. Nat Commun 2021; 12:6284. [PMID: 34725357 PMCID: PMC8560856 DOI: 10.1038/s41467-021-26608-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 10/14/2021] [Indexed: 11/26/2022] Open
Abstract
TRPV6 is a calcium-selective ion channel implicated in epithelial Ca2+ uptake. TRPV6 inhibitors are needed for the treatment of a broad range of diseases associated with disturbed calcium homeostasis, including cancers. Here we combine cryo-EM, calcium imaging, and mutagenesis to explore molecular bases of human TRPV6 inhibition by the antifungal drug econazole and the universal ion channel blocker ruthenium red (RR). Econazole binds to an allosteric site at the channel's periphery, where it replaces a lipid. In contrast, RR inhibits TRPV6 by binding in the middle of the ion channel's selectivity filter and plugging its pore like a bottle cork. Despite different binding site locations, both inhibitors induce similar conformational changes in the channel resulting in closure of the gate formed by S6 helices bundle crossing. The uncovered molecular mechanisms of TRPV6 inhibition can guide the design of a new generation of clinically useful inhibitors.
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Affiliation(s)
- Arthur Neuberger
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Kirill D Nadezhdin
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Alexander I Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA.
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Ali II, Shah I, Marzouk S, Karam SM, Al Menhali A. Vitamin D Is Necessary for Murine Gastric Epithelial Homeostasis. BIOLOGY 2021; 10:biology10080705. [PMID: 34439938 PMCID: PMC8389223 DOI: 10.3390/biology10080705] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 07/20/2021] [Accepted: 07/20/2021] [Indexed: 02/07/2023]
Abstract
Unlike other organs, the importance of VD in a normal stomach is unknown. This study focuses on understanding the physiological role of vitamin D in gastric epithelial homeostasis. C57BL/6J mice were divided into three groups that were either fed a standard diet and kept in normal light/dark cycles (SDL), fed a standard diet but kept in the dark (SDD) or fed a vitamin D-deficient diet and kept in the dark (VDD). After 3 months, sera were collected to measure vitamin D levels by LC-MS/MS, gastric tissues were collected for immunohistochemical and gene expression analyses and gastric contents were collected to measure acid levels. The VDD group showed a significant decrease in the acid-secreting parietal cell-specific genes Atp4a and Atp4b when compared with the controls. This reduction was associated with an increased expression of an antral gastrin hormone. VDD gastric tissues also showed a high proliferation rate compared with SDL and SDD using an anti-BrdU antibody. This study indicates the requirement for normal vitamin D levels for proper parietal cell functions.
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Affiliation(s)
- Ifrah Ismail Ali
- Department of Biology, College of Science, United Arab Emirates University, Al Ain 15551, United Arab Emirates;
| | - Iltaf Shah
- Department of Chemistry, College of Science, United Arab Emirates University, Al Ain 15551, United Arab Emirates; (I.S.); (S.M.)
| | - Sayed Marzouk
- Department of Chemistry, College of Science, United Arab Emirates University, Al Ain 15551, United Arab Emirates; (I.S.); (S.M.)
| | - Sherif M. Karam
- Department of Anatomy, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain 15551, United Arab Emirates;
| | - Asma Al Menhali
- Department of Biology, College of Science, United Arab Emirates University, Al Ain 15551, United Arab Emirates;
- Correspondence: ; Tel.: +971-3-713-6380
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Wongdee K, Chanpaisaeng K, Teerapornpuntakit J, Charoenphandhu N. Intestinal Calcium Absorption. Compr Physiol 2021; 11:2047-2073. [PMID: 34058017 DOI: 10.1002/cphy.c200014] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In this article, we focus on mammalian calcium absorption across the intestinal epithelium in normal physiology. Intestinal calcium transport is essential for supplying calcium for metabolism and bone mineralization. Dietary calcium is transported across the mucosal epithelia via saturable transcellular and nonsaturable paracellular pathways, both of which are under the regulation of 1,25-dihydroxyvitamin D3 and several other endocrine and paracrine factors, such as parathyroid hormone, prolactin, 17β-estradiol, calcitonin, and fibroblast growth factor-23. Calcium absorption occurs in several segments of the small and large intestine with varying rates and capacities. Segmental heterogeneity also includes differential expression of calcium transporters/carriers (e.g., transient receptor potential cation channel and calbindin-D9k ) and the presence of favorable factors (e.g., pH, luminal contents, and gut motility). Other proteins and transporters (e.g., plasma membrane vitamin D receptor and voltage-dependent calcium channels), as well as vesicular calcium transport that probably contributes to intestinal calcium absorption, are also discussed. © 2021 American Physiological Society. Compr Physiol 11:1-27, 2021.
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Affiliation(s)
- Kannikar Wongdee
- Faculty of Allied Health Sciences, Burapha University, Chonburi, Thailand.,Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Krittikan Chanpaisaeng
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand.,Functional Ingredients and Food Innovation Research Group, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, Thailand
| | - Jarinthorn Teerapornpuntakit
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand.,Department of Physiology, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand
| | - Narattaphol Charoenphandhu
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand.,Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand.,Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand.,The Academy of Science, The Royal Society of Thailand, Bangkok, Thailand
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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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Ma J, Zhu L, Zhou Z, Song T, Yang L, Yan X, Chen A, Ye TW. The calcium channel TRPV6 is a novel regulator of RANKL-induced osteoclastic differentiation and bone absorption activity through the IGF-PI3K-AKT pathway. Cell Prolif 2020; 54:e12955. [PMID: 33159483 PMCID: PMC7791174 DOI: 10.1111/cpr.12955] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 10/01/2020] [Accepted: 10/20/2020] [Indexed: 12/18/2022] Open
Abstract
Objectives Calcium ion signals are important for osteoclast differentiation. Transient receptor potential vanilloid 6 (TRPV6) is a regulator of bone homeostasis. However, it was unclear whether TRPV6 was involved in osteoclast formation. Therefore, the aim of this study was to evaluate the role of TPRV6 in bone metabolism and to clarify its regulatory role in osteoclasts at the cellular level. Materials and methods Bone structure and histological changes in Trpv6 knockout mice were examined using micro‐computed tomography and histological analyses. To investigate the effects of Trpv6 on osteoclast function, we silenced or overexpressed Trpv6 in osteoclasts via lentivirus transfection, respectively. Osteoclast differentiation and bone resorption viability were measured by tartrate‐resistant acid phosphatase (TRAP) staining and pit formation assays. The expression of osteoclast marker genes, including cathepsin k, DC‐STAMP, Atp6v0d2 and TRAP, was measured by qRT‐PCR. Cell immunofluorescence and Western blotting were applied to explore the mechanisms by which the IGF‐PI3K‐AKT pathway was involved in the regulation of osteoclast formation and bone resorption by Trpv6. Results We found that knockout of Trpv6 induced osteoporosis and enhanced bone resorption in mice, but did not affect bone formation. Further studies showed that Trpv6, which was distributed on the cell membrane of osteoclasts, acted as a negative regulator for osteoclast differentiation and function. Mechanistically, Trpv6 suppressed osteoclastogenesis by decreasing the ratios of phosphoprotein/total protein in the IGF–PI3K–AKT signalling pathway. Blocking of the IGF–PI3K–AKT pathway significantly alleviated the inhibitory effect of Trpv6 on osteoclasts formation. Conclusions Our study confirmed the important role of Trpv6 in bone metabolism and clarified its regulatory role in osteoclasts at the cellular level. Taken together, this study may inspire a new strategy for the treatment of osteoporosis.
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Affiliation(s)
- Jun Ma
- Department of Orthopedic Trauma Surgery, Changzheng Hospital, The Second Military Medical University, Shanghai, China.,Department of Health Statistics, The Second Military Medical University, Shanghai, China
| | - Lei Zhu
- Department of Orthopedic Trauma Surgery, Changzheng Hospital, The Second Military Medical University, Shanghai, China
| | - Zhibin Zhou
- Department of Orthopedic Surgery, General Hospital of Northern Theater Command, Shenyang, China
| | - Tengfei Song
- Department of Orthopedic Trauma Surgery, Changzheng Hospital, The Second Military Medical University, Shanghai, China
| | - Lei Yang
- Department of Orthopedic Surgery, The 2nd affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Xu Yan
- Department of Orthopedic Surgery, Naval Characteristic Medical Center, The Second Military Medical University, Shanghai, China
| | - Aimin Chen
- Department of Orthopedic Trauma Surgery, Changzheng Hospital, The Second Military Medical University, Shanghai, China
| | - Tian Wen Ye
- Department of Orthopedic Trauma Surgery, Changzheng Hospital, The Second Military Medical University, Shanghai, China
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Manganese-enhanced MRI (MEMRI) in breast and prostate cancers: Preliminary results exploring the potential role of calcium receptors. PLoS One 2020; 15:e0224414. [PMID: 32931488 PMCID: PMC7491733 DOI: 10.1371/journal.pone.0224414] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 08/12/2020] [Indexed: 12/12/2022] Open
Abstract
Procedures To preliminary assess the relationship between Manganese Enhanced Magnetic Resonance Imaging (MEMRI) and the expression of calcium receptors in human prostate and breast cancer animal models. Methods NOD/SCID mice were inoculated with MDA-MB-231 breast cancer cells and prostate PC3 cancer cells to develop orthotopic or pseudometastatic cancer animal models. Mice were studied on a clinical 3T scanner by using a prototype birdcage coil before and after intravenous injection of MnCl2. Assessment of receptor’s status was carried out after the MR images acquisition by immunohistochemistry on excised tumours. Results Manganese contrast enhancement in breast or prostate cancer animal models well correlated with CaSR expression (p<0.01), whereas TRPV6 expression levels appeared not relevant to the Mn uptake. Conclusion Our preliminary results suggest that MEMRI appears an efficient tool to characterize human breast and prostate cancer animal models in the presence of different expression level of calcium receptors.
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9
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Sun M, Wu X, Yu Y, Wang L, Xie D, Zhang Z, Chen L, Lu A, Zhang G, Li F. Disorders of Calcium and Phosphorus Metabolism and the Proteomics/Metabolomics-Based Research. Front Cell Dev Biol 2020; 8:576110. [PMID: 33015068 PMCID: PMC7511772 DOI: 10.3389/fcell.2020.576110] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 08/20/2020] [Indexed: 12/19/2022] Open
Abstract
Since calcium and phosphorus play vital roles in a multitude of physiologic systems, disorders of calcium and phosphorus metabolism always lead to severe consequences such as skeletal-related and cardiovascular morbidity, or even life-threatening. Physiologically, the maintenance of calcium and phosphorus homeostasis is achieved via a variety of concerted actions of hormones such as parathyroid hormone (PTH), vitamin D, and fibroblast growth factor (FGF23), which could be regulated mainly at three organs, the intestine, kidney, and bone. Disruption of any organ or factor might lead to disorders of calcium and phosphorus metabolism. Currently, lacking of accurate diagnostic approaches and unknown molecular basis of pathophysiology will result in patients being unable to receive a precise diagnosis and personalized treatment timely. Therefore, it is urgent to identify early diagnostic biomarkers and develop therapeutic strategies. Fortunately, proteomics and metabolomics offer promising tools to discover novel indicators and further understanding of pathological mechanisms. Therefore, in this review, we will give a systematic introduction on PTH-1,25(OH)2D-FGF23 axis in the disorders of calcium and phosphorus metabolism, diagnostic biomarkers identified, and potential altered metabolic pathways involved.
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Affiliation(s)
- Meiheng Sun
- Law Sau Fai Institute for Advancing Translational Medicine in Bone and Joint Diseases, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tsai, Hong Kong.,Institute of Integrated Bioinfomedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tsai, Hong Kong.,Institute of Precision Medicine and Innovative Drug Discovery, HKBU Institute for Research and Continuing Education, Shenzhen, China.,Jiangsu Key Laboratory of Xenotransplantation, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Xiaoqiu Wu
- Law Sau Fai Institute for Advancing Translational Medicine in Bone and Joint Diseases, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tsai, Hong Kong.,Institute of Integrated Bioinfomedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tsai, Hong Kong.,Institute of Precision Medicine and Innovative Drug Discovery, HKBU Institute for Research and Continuing Education, Shenzhen, China
| | - Yuanyuan Yu
- Law Sau Fai Institute for Advancing Translational Medicine in Bone and Joint Diseases, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tsai, Hong Kong.,Institute of Integrated Bioinfomedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tsai, Hong Kong.,Institute of Precision Medicine and Innovative Drug Discovery, HKBU Institute for Research and Continuing Education, Shenzhen, China
| | - Luyao Wang
- Law Sau Fai Institute for Advancing Translational Medicine in Bone and Joint Diseases, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tsai, Hong Kong.,Institute of Integrated Bioinfomedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tsai, Hong Kong.,Institute of Precision Medicine and Innovative Drug Discovery, HKBU Institute for Research and Continuing Education, Shenzhen, China
| | - Duoli Xie
- Law Sau Fai Institute for Advancing Translational Medicine in Bone and Joint Diseases, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tsai, Hong Kong.,Institute of Integrated Bioinfomedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tsai, Hong Kong
| | - Zhenlin Zhang
- Shanghai Clinical Research Center of Bone Disease, Department of Osteoporosis and Bone Disease, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Lin Chen
- Department of Wound Repair and Rehabilitation Medicine, State Key Laboratory of Trauma, Burns and Combined Injury, Trauma Center, Research Institute of Surgery, Daping Hospital, Army Medical University, Chongqing, China
| | - Aiping Lu
- Law Sau Fai Institute for Advancing Translational Medicine in Bone and Joint Diseases, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tsai, Hong Kong.,Institute of Integrated Bioinfomedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tsai, Hong Kong.,Institute of Precision Medicine and Innovative Drug Discovery, HKBU Institute for Research and Continuing Education, Shenzhen, China.,Institute of Basic Research in Clinical Medicine, China Academy of Chinese Medical Sciences, Beijing, China.,Institute of Arthritis Research, Shanghai Academy of Chinese Medical Sciences, Shanghai, China
| | - Ge Zhang
- Law Sau Fai Institute for Advancing Translational Medicine in Bone and Joint Diseases, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tsai, Hong Kong.,Institute of Integrated Bioinfomedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tsai, Hong Kong.,Institute of Precision Medicine and Innovative Drug Discovery, HKBU Institute for Research and Continuing Education, Shenzhen, China
| | - Fangfei Li
- Law Sau Fai Institute for Advancing Translational Medicine in Bone and Joint Diseases, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tsai, Hong Kong.,Institute of Integrated Bioinfomedicine and Translational Science, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tsai, Hong Kong.,Institute of Precision Medicine and Innovative Drug Discovery, HKBU Institute for Research and Continuing Education, Shenzhen, China
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10
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Evolutionary analyses reveal independent origins of gene repertoires and structural motifs associated to fast inactivation in calcium-selective TRPV channels. Sci Rep 2020; 10:8684. [PMID: 32457384 PMCID: PMC7250927 DOI: 10.1038/s41598-020-65679-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 04/23/2020] [Indexed: 01/14/2023] Open
Abstract
Essential for calcium homeostasis, TRPV5 and TRPV6 are calcium-selective channels belonging to the transient receptor potential (TRP) gene family. In this study, we investigated the evolutionary history of these channels to add an evolutionary context to the already available physiological information. Phylogenetic analyses revealed that paralogs found in mammals, sauropsids, amphibians, and chondrichthyes, are the product of independent duplication events in the ancestor of each group. Within amniotes, we identified a traceable signature of three amino acids located at the amino-terminal intracellular region. The signature correlates with both the duplication events and the phenotype of fast inactivation observed in mammalian TRPV6 channels. Electrophysiological recordings and mutagenesis revealed that the signature sequence modulates the phenotype of fast inactivation in all clades of vertebrates but reptiles. A transcriptome analysis showed a change in tissue expression from gills, in marine vertebrates, to kidneys in terrestrial vertebrates. Our results highlight a cytoplasmatic structural triad composed by the Helix-Loop-Helix domain, the S2-S3 linker, and the TRP domain helix that is important on modulating the activity of calcium-selective TRPV channels.
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11
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TRPV Subfamily (TRPV2, TRPV3, TRPV4, TRPV5, and TRPV6) Gene and Protein Expression in Patients with Ulcerative Colitis. J Immunol Res 2020; 2020:2906845. [PMID: 32455137 PMCID: PMC7231094 DOI: 10.1155/2020/2906845] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 03/04/2020] [Accepted: 04/11/2020] [Indexed: 12/22/2022] Open
Abstract
Introduction TRPVs are a group of receptors with a channel activity predominantly permeable to Ca2+. This subfamily is involved in the development of gastrointestinal diseases such as ulcerative colitis (UC). The aim of the study was to characterize the gene and protein expression of the TRPV subfamily in UC patients and controls. Methods We determined by quantitative PCR the gene expression of TRPV2, TRPV3, TRPV4, TRPV5, and TRPV6 in 45 UC patients (29 active UC and 16 remission UC) and 26 noninflamed controls. Protein expression was evaluated in 5 μm thick sections of formalin-fixed, paraffin-embedded tissue from 5 customized severe active UC patients and 5 control surgical specimens. Results TRPV2 gene expression was increased in the control group compared with active UC and remission patients (P = 0.002 and P = 0.05, respectively). TRPV3 gene expression was significantly higher in controls than in active UC patients (P = 0.002). The gene expression of TRPV4 was significantly higher in colonic tissue from patients with remission UC compared with active UC patients (P = 0.05) and controls (P = 0.005). TRPV5 had significantly higher mRNA levels in a control group compared with active UC patients (P = 0.02). The gene expression of TRPV6 was significantly higher in the colonic tissue from patients with active UC compared with the control group (P = 0.05). The protein expression of TRPV2 was upregulated in the mucosa and submucosa from the controls compared with the UC patients (P ≤ 0.003). The protein expression of TRPV3 and TRPV4 was upregulated in all intestinal layers from the controls compared with the UC patients (P < 0.001). TRPV5 was upregulated in the submucosa and serosa from the controls vs. UC patients (P < 0.001). TRPV6 was upregulated in all intestinal layers from the UC patients vs. controls (P ≤ 0.001). Conclusion The TRPV subfamily clearly showed a differential expression in the UC patients compared with the controls, suggesting their role in the pathophysiology of UC.
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12
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Yelshanskaya MV, Nadezhdin KD, Kurnikova MG, Sobolevsky AI. Structure and function of the calcium-selective TRP channel TRPV6. J Physiol 2020; 599:2673-2697. [PMID: 32073143 DOI: 10.1113/jp279024] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Accepted: 02/03/2020] [Indexed: 12/23/2022] Open
Abstract
Epithelial calcium channel TRPV6 is a member of the vanilloid subfamily of TRP channels that is permeable to cations and highly selective to Ca2+ ; it shows constitutive activity regulated negatively by Ca2+ and positively by phosphoinositol and cholesterol lipids. In this review, we describe the molecular structure of TRPV6 and discuss how its structural elements define its unique functional properties. High Ca2+ selectivity of TRPV6 originates from the narrow selectivity filter, where Ca2+ ions are directly coordinated by a ring of anionic aspartate side chains. Divalent cations Ca2+ and Ba2+ permeate TRPV6 pore according to the knock-off mechanism, while tight binding of Gd3+ to the aspartate ring blocks the channel and prevents Na+ from permeating the pore. The iris-like channel opening is accompanied by an α-to-π helical transition in the pore-lining transmembrane helix S6. As a result of this transition, the intracellular halves of the S6 helices bend and rotate by about 100 deg, exposing different residues to the channel pore in the open and closed states. Channel opening is also associated with changes in occupancy of the transmembrane domain lipid binding sites. The inhibitor 2-aminoethoxydiphenyl borate (2-APB) binds to TRPV6 in a pocket formed by the cytoplasmic half of the S1-S4 transmembrane helical bundle and shifts open-closed channel equilibrium towards the closed state by outcompeting lipids critical for activation. Ca2+ inhibits TRPV6 via binding to calmodulin (CaM), which mediates Ca2+ -dependent inactivation. The TRPV6-CaM complex exhibits 1:1 stoichiometry; one TRPV6 tetramer binds both CaM lobes, which adopt a distinct head-to-tail arrangement. The CaM C-terminal lobe plugs the channel through a unique cation-π interaction by inserting the side chain of lysine K115 into a tetra-tryptophan cage at the ion channel pore intracellular entrance. Recent studies of TRPV6 structure and function described in this review advance our understanding of the role of this channel in physiology and pathophysiology and inform new therapeutic design.
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Affiliation(s)
- Maria V Yelshanskaya
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, NY, 10032, USA
| | - Kirill D Nadezhdin
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, NY, 10032, USA
| | - Maria G Kurnikova
- Chemistry Department, Carnegie Mellon University, 4400 Fifth Ave, Pittsburgh, PA, 15213, USA
| | - Alexander I Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, NY, 10032, USA
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Abstract
Two decades ago a class of ion channels, hitherto unsuspected, was discovered. In mammals these Transient Receptor Potential channels (TRPs) have not only expanded in number (to 26 functional channels) but also expanded the view of our interface with the physical and chemical environment. Some are heat and cold sensors while others monitor endogenous and/or exogenous chemical signals. Some TRP channels monitor osmotic potential, and others measure cell movement, stretching, and fluid flow. Many TRP channels are major players in nociception and integration of pain signals. One member of the vanilloid sub-family of channels is TRPV6. This channel is highly selective for divalent cations, particularly calcium, and plays a part in general whole-body calcium homeostasis, capturing calcium in the gut from the diet. TRPV6 can be greatly elevated in a number of cancers deriving from epithelia and considerable study has been made of its role in the cancer phenotype where calcium control is dysfunctional. This review compiles and updates recent published work on TRPV6 as a promising drug target in a number of cancers including those afflicting breast, ovarian, prostate and pancreatic tissues.
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Affiliation(s)
- John M. Stewart
- Soricimed Biopharma Inc. 18 Botsford Street, Moncton, NB, Canada, E1C 4W7
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14
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Hughes TE, Del Rosario JS, Kapoor A, Yazici AT, Yudin Y, Fluck EC, Filizola M, Rohacs T, Moiseenkova-Bell VY. Structure-based characterization of novel TRPV5 inhibitors. eLife 2019; 8:49572. [PMID: 31647410 PMCID: PMC6834369 DOI: 10.7554/elife.49572] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 10/23/2019] [Indexed: 12/31/2022] Open
Abstract
Transient receptor potential vanilloid 5 (TRPV5) is a highly calcium selective ion channel that acts as the rate-limiting step of calcium reabsorption in the kidney. The lack of potent, specific modulators of TRPV5 has limited the ability to probe the contribution of TRPV5 in disease phenotypes such as hypercalcemia and nephrolithiasis. Here, we performed structure-based virtual screening (SBVS) at a previously identified TRPV5 inhibitor binding site coupled with electrophysiology screening and identified three novel inhibitors of TRPV5, one of which exhibits high affinity, and specificity for TRPV5 over other TRP channels, including its close homologue TRPV6. Cryo-electron microscopy of TRPV5 in the presence of the specific inhibitor and its parent compound revealed novel binding sites for this channel. Structural and functional analysis have allowed us to suggest a mechanism of action for the selective inhibition of TRPV5 and lay the groundwork for rational design of new classes of TRPV5 modulators.
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Affiliation(s)
- Taylor Et Hughes
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - John Smith Del Rosario
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, United States
| | - Abhijeet Kapoor
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, United States
| | - Aysenur Torun Yazici
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, United States
| | - Yevgen Yudin
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, United States
| | - Edwin C Fluck
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Marta Filizola
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, United States
| | - Tibor Rohacs
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, United States
| | - Vera Y Moiseenkova-Bell
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
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15
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Beggs MR, Lee JJ, Busch K, Raza A, Dimke H, Weissgerber P, Engel J, Flockerzi V, Alexander RT. TRPV6 and Ca v1.3 Mediate Distal Small Intestine Calcium Absorption Before Weaning. Cell Mol Gastroenterol Hepatol 2019; 8:625-642. [PMID: 31398491 PMCID: PMC6889763 DOI: 10.1016/j.jcmgh.2019.07.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 07/15/2019] [Accepted: 07/17/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Intestinal Ca2+ absorption early in life is vital to achieving optimal bone mineralization. The molecular details of intestinal Ca2+ absorption have been defined in adults after peak bone mass is obtained, but they are largely unexplored during development. We sought to delineate the molecular details of transcellular Ca2+ absorption during this critical period. METHODS Expression of small intestinal and renal calcium transport genes was assessed by using quantitative polymerase chain reaction. Net calcium flux across small intestinal segments was measured in Ussing chambers, including after pharmacologic inhibition or genetic manipulation of TRPV6 or Cav1.3 calcium channels. Femurs were analyzed by using micro-computed tomography and histology. RESULTS Net TRPV6-mediated Ca2+ flux across the duodenum was absent in pre-weaned (P14) mice but present after weaning. In contrast, we found significant transcellular Ca2+ absorption in the jejunum at 2 weeks but not 2 months of age. Net jejunal Ca2+ absorption observed at P14 was not present in either Trpv6 mutant (D541A) mice or Cav1.3 knockout mice. We observed significant nifedipine-sensitive transcellular absorption across the ileum at P14 but not 2 months. Cav1.3 knockout pups exhibited delayed bone mineral accrual, compensatory nifedipine-insensitive Ca2+ absorption in the ileum, and increased expression of renal Ca2+ reabsorption mediators at P14. Moreover, weaning pups at 2 weeks reduced jejunal and ileal Cav1.3 expression. CONCLUSIONS We have detailed novel pathways contributing to transcellular Ca2+ transport across the distal small intestine of mice during development, highlighting the complexity of the multiple mechanisms involved in achieving a positive Ca2+ balance early in life.
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Affiliation(s)
- Megan R. Beggs
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada,The Women’s & Children’s Health Research Institute, Edmonton, Alberta, Canada
| | - Justin J. Lee
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada,The Women’s & Children’s Health Research Institute, Edmonton, Alberta, Canada
| | - Kai Busch
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, Homburg, Germany
| | - Ahsan Raza
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, Homburg, Germany
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Petra Weissgerber
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, Homburg, Germany
| | - Jutta Engel
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine (CIPMM), Saarland University, School of Medicine, Homburg, Germany
| | - Veit Flockerzi
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, Homburg, Germany
| | - R. Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada,The Women’s & Children’s Health Research Institute, Edmonton, Alberta, Canada,Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada,Correspondence Address correspondence to: R. Todd Alexander, MD, PhD, Department of Pediatrics, 4-585 Edmonton Clinic Health Academy, 11405 – 87 Avenue, University of Alberta, Edmonton, Alberta T6G 2R7, Canada. fax: (780) 248-5556.
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16
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Tang KC, Pan W, Doschak MR, Alexander RT. Increased FoxO3a expression prevents osteoblast differentiation and matrix calcification. Bone Rep 2019; 10:100206. [PMID: 31193232 PMCID: PMC6522754 DOI: 10.1016/j.bonr.2019.100206] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 04/16/2019] [Accepted: 04/22/2019] [Indexed: 10/28/2022] Open
Abstract
Forkhead Box O transcription factors play important roles in bone metabolism by defending against oxidative stress and apoptosis. FoxO3a is of special interest as it is the predominant isoform expressed in bone. In osteoblasts, the administration of 1,25 dihydroxyvitamin D3 (1,25D3) increases FoxO3a expression, and alters calcium handling. We therefore queried whether FoxO3a participates in vitamin D-mediated regulation of calcium transport pathways or matrix calcification, independent of reactive oxygen species (ROS) formation. To examine this possibility, we differentiated MC3T3-E1 cells into mature osteoblast-like cells over 7 days. This coincided with an increased ability to mineralize extracellular matrix. FoxO3a expression increased throughout differentiation. 1,25D3 enhanced both FoxO3a mRNA and protein expression. Immunofluorescence microscopy found increased FoxO3a nuclear localization with differentiation and after treatment with 1,25D3. Live cell ratiometric imaging with Fura-2AM identified significant L-type calcium channel mediated calcium uptake that was enhanced by 1,25D3. We observed expression of both Cav1.2 and Cav1.3, although expression decreased throughout differentiation and was not altered by 1,25D3 treatment. FoxO3a overexpression reduced calcium uptake and calcium deposition. FoxO3a overexpression also prevented alterations in calcium channel expression and the cell differentiation associated decrease in expression of Runx2 and increased expression of osteocalcin, findings consistent with a failure for the cells to differentiate. Based on both our expression and functional data, we suggest that high levels of FoxO3a prevent osteoblast differentiation and matrix calcification.
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Affiliation(s)
- Kathy C Tang
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta T6G 2R7, Canada
| | - Wanling Pan
- Department of Physiology, The University of Alberta, Edmonton, Alberta T6G 2R7, Canada
| | - Michael R Doschak
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta T6G 2R7, Canada
| | - R Todd Alexander
- Department of Physiology, The University of Alberta, Edmonton, Alberta T6G 2R7, Canada.,Department of Pediatrics, The University of Alberta, Edmonton, Alberta T6G 2R7, Canada.,The Women's & Children's Health Research Institute, 11405-87 Avenue, Edmonton, Alberta T6G 1C9, Canada
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17
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Lee JJ, Liu X, O'Neill D, Beggs MR, Weissgerber P, Flockerzi V, Chen XZ, Dimke H, Alexander RT. Activation of the calcium sensing receptor attenuates TRPV6-dependent intestinal calcium absorption. JCI Insight 2019; 5:128013. [PMID: 31013259 DOI: 10.1172/jci.insight.128013] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Plasma calcium (Ca2+) is maintained by amending the release of parathyroid hormone and through direct effects of the Ca2+ sensing receptor (CaSR) in the renal tubule. Combined, these mechanisms alter intestinal Ca2+ absorption by modulating 1,25-dihydroxy vitamin D3 production, bone resorption, and renal Ca2+ excretion. The CaSR is a therapeutic target in the treatment of secondary hyperparathyroidism and hypocalcemia a common complication of calcimimetic therapy. The CaSR is also expressed in intestinal epithelium, however, a direct role in regulating local intestinal Ca2+ absorption is unknown. Chronic CaSR activation decreased expression of genes involved in Ca2+ absorption. In Ussing chambers, increasing extracellular Ca2+ or basolateral application of the calcimimetic cinacalcet decreased net Ca2+ absorption across intestinal preparations acutely. Conversely, Ca2+ absorption increased with decreasing extracellular Ca2+ concentration. These responses were absent in mice expressing a non-functional TRPV6, TRPV6D541A. Cinacalcet also attenuated Ca2+ fluxes through TRPV6 in Xenopus oocytes when co-expressed with the CaSR. Moreover, the phospholipase C inhibitor, U73122, prevented cinacalcet-mediated inhibition of Ca2+ flux. These results reveal a regulatory pathway whereby activation of the CaSR in the basolateral membrane of the intestine directly attenuates local Ca2+ absorption via TRPV6 to prevent hypercalcemia and help explain how calcimimetics induce hypocalcemia.
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Affiliation(s)
- Justin J Lee
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada.,The Women's and Children's Health Research Institute, Edmonton, Alberta, Canada
| | - Xiong Liu
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - Debbie O'Neill
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - Megan R Beggs
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada.,The Women's and Children's Health Research Institute, Edmonton, Alberta, Canada
| | - Petra Weissgerber
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, Hamburg, Germany
| | - Veit Flockerzi
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, Hamburg, Germany
| | - Xing-Zhen Chen
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark.,Department of Nephrology, Odense University Hospital, Odense, Denmark
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada.,The Women's and Children's Health Research Institute, Edmonton, Alberta, Canada.,Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
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18
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Gallelli CA, Calcagnini S, Romano A, Koczwara JB, de Ceglia M, Dante D, Villani R, Giudetti AM, Cassano T, Gaetani S. Modulation of the Oxidative Stress and Lipid Peroxidation by Endocannabinoids and Their Lipid Analogues. Antioxidants (Basel) 2018; 7:E93. [PMID: 30021985 PMCID: PMC6070960 DOI: 10.3390/antiox7070093] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 07/10/2018] [Accepted: 07/13/2018] [Indexed: 02/06/2023] Open
Abstract
Growing evidence supports the pivotal role played by oxidative stress in tissue injury development, thus resulting in several pathologies including cardiovascular, renal, neuropsychiatric, and neurodegenerative disorders, all characterized by an altered oxidative status. Reactive oxygen and nitrogen species and lipid peroxidation-derived reactive aldehydes including acrolein, malondialdehyde, and 4-hydroxy-2-nonenal, among others, are the main responsible for cellular and tissue damages occurring in redox-dependent processes. In this scenario, a link between the endocannabinoid system (ECS) and redox homeostasis impairment appears to be crucial. Anandamide and 2-arachidonoylglycerol, the best characterized endocannabinoids, are able to modulate the activity of several antioxidant enzymes through targeting the cannabinoid receptors type 1 and 2 as well as additional receptors such as the transient receptor potential vanilloid 1, the peroxisome proliferator-activated receptor alpha, and the orphan G protein-coupled receptors 18 and 55. Moreover, the endocannabinoids lipid analogues N-acylethanolamines showed to protect cell damage and death from reactive aldehydes-induced oxidative stress by restoring the intracellular oxidants-antioxidants balance. In this review, we will provide a better understanding of the main mechanisms triggered by the cross-talk between the oxidative stress and the ECS, focusing also on the enzymatic and non-enzymatic antioxidants as scavengers of reactive aldehydes and their toxic bioactive adducts.
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Affiliation(s)
- Cristina Anna Gallelli
- Department of Physiology and Pharmacology "V. Erspamer", Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy.
| | - Silvio Calcagnini
- Department of Physiology and Pharmacology "V. Erspamer", Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy.
| | - Adele Romano
- Department of Physiology and Pharmacology "V. Erspamer", Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy.
| | - Justyna Barbara Koczwara
- Department of Physiology and Pharmacology "V. Erspamer", Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy.
| | - Marialuisa de Ceglia
- Department of Physiology and Pharmacology "V. Erspamer", Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy.
| | - Donatella Dante
- Department of Physiology and Pharmacology "V. Erspamer", Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy.
| | - Rosanna Villani
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Department of Medical and Surgical Sciences, Institute of Internal Medicine, University of Foggia, 71122 Foggia, Italy.
| | - Anna Maria Giudetti
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Monteroni, 73100 Lecce, Italy.
| | - Tommaso Cassano
- Department of Clinical and Experimental Medicine, University of Foggia, Via Luigi Pinto, c/o Ospedali Riuniti, 71122 Foggia, Italy.
| | - Silvana Gaetani
- Department of Physiology and Pharmacology "V. Erspamer", Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy.
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19
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TRPV6 Variants Interfere with Maternal-Fetal Calcium Transport through the Placenta and Cause Transient Neonatal Hyperparathyroidism. Am J Hum Genet 2018; 102:1104-1114. [PMID: 29861107 DOI: 10.1016/j.ajhg.2018.04.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2017] [Accepted: 04/06/2018] [Indexed: 11/22/2022] Open
Abstract
Transient neonatal hyperparathyroidism (TNHP) is etiologically a heterogeneous condition. One of the etiologies is an insufficient maternal-fetal calcium transport through the placenta. We report six subjects with homozygous and/or compound-heterozygous mutations in the gene encoding the transient receptor potential cation channel, subfamily V, member 6 (TRPV6), an epithelial Ca2+-selective channel associated with this condition. Exome sequencing on two neonates with skeletal findings consistent with neonatal hyperparathyroidism identified homozygous frameshift mutations before the first transmembrane domain in a subject born to first-cousins parents of Pakistani descent as well as compound-heterozygous mutations (a combination of a frameshift mutation and an intronic mutation that alters mRNA splicing) in an individual born to a non-consanguineous couple of African descent. Subsequently, targeted mutation analysis of TRPV6 performed on four other individuals (born to non-consanguineous Japanese parents) with similar X-rays findings identified compound-heterozygous mutations. The skeletal findings improved or resolved in most subjects during the first few months of life. We identified three missense variants (at the outer edges of the second and third transmembrane domains) that alter the localization of the TRPV6: one recurrent variant at the S2-S3 loop and two recurrent variants (in the fourth ankyrin repeat domain) that impair TRPV6 stability. Compound heterozygous loss-of-function mutations for the pathogenic frameshift allele and the allele with an intronic c.607+5G>A mutation resulted in the most severe phenotype. These results suggest that TNHP is an autosomal-recessive disease caused by TRPV6 mutations that affect maternal-fetal calcium transport.
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20
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Aldosterone, SGK1, and ion channels in the kidney. Clin Sci (Lond) 2018; 132:173-183. [PMID: 29352074 PMCID: PMC5817097 DOI: 10.1042/cs20171525] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 12/15/2017] [Accepted: 12/19/2017] [Indexed: 12/14/2022]
Abstract
Hyperaldosteronism, a common cause of hypertension, is strongly connected to Na+, K+, and Mg2+ dysregulation. Owing to its steroidal structure, aldosterone is an active transcriptional modifier when bound to the mineralocorticoid receptor (MR) in cells expressing the enzyme 11β-hydroxysteroid dehydrogenase 2, such as those comprising the aldosterone-sensitive distal nephron (ASDN). One such up-regulated protein, the ubiquitous serum and glucocorticoid regulated kinase 1 (SGK1), has the capacity to modulate the surface expression and function of many classes of renal ion channels, including those that transport Na+ (ENaC), K+ (ROMK/BK), Ca2+ (TRPV4/5/6), Mg2+ (TRPM7/6), and Cl− (ClC-K, CFTR). Here, we discuss the mechanisms by which ASDN expressed channels are up-regulated by SGK1, while highlighting newly discovered pathways connecting aldosterone to nonselective cation channels that are permeable to Mg2+ (TRPM7) or Ca2+ (TRPV4).
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21
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Hughes TET, Lodowski DT, Huynh KW, Yazici A, Del Rosario J, Kapoor A, Basak S, Samanta A, Han X, Chakrapani S, Zhou ZH, Filizola M, Rohacs T, Han S, Moiseenkova-Bell VY. Structural basis of TRPV5 channel inhibition by econazole revealed by cryo-EM. Nat Struct Mol Biol 2018; 25:53-60. [PMID: 29323279 PMCID: PMC5951624 DOI: 10.1038/s41594-017-0009-1] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Accepted: 11/13/2017] [Indexed: 12/18/2022]
Abstract
The transient receptor potential vanilloid 5 (TRPV5) channel is a member of the transient receptor potential (TRP) channel family, which is highly selective for Ca2+, that is present primarily at the apical membrane of distal tubule epithelial cells in the kidney and plays a key role in Ca2+ reabsorption. Here we present the structure of the full-length rabbit TRPV5 channel as determined using cryo-EM in complex with its inhibitor econazole. This structure reveals that econazole resides in a hydrophobic pocket analogous to that occupied by phosphatidylinositides and vanilloids in TRPV1, thus suggesting conserved mechanisms for ligand recognition and lipid binding among TRPV channels. The econazole-bound TRPV5 structure adopts a closed conformation with a distinct lower gate that occludes Ca2+ permeation through the channel. Structural comparisons between TRPV5 and other TRPV channels, complemented with molecular dynamics (MD) simulations of the econazole-bound TRPV5 structure, allowed us to gain mechanistic insight into TRPV5 channel inhibition by small molecules.
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Affiliation(s)
- Taylor E T Hughes
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - David T Lodowski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
- Department of Nutrition, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Kevin W Huynh
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA
| | - Aysenur Yazici
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - John Del Rosario
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Abhijeet Kapoor
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Sandip Basak
- Department of Physiology and Biophysics School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Amrita Samanta
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
- Department of Physiology and Biophysics School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Xu Han
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Sudha Chakrapani
- Department of Physiology and Biophysics School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Z Hong Zhou
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA
| | - Marta Filizola
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Tibor Rohacs
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Seungil Han
- Pfizer Research and Development, Groton, CT, USA
| | - Vera Y Moiseenkova-Bell
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
- Department of Physiology and Biophysics School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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22
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McGoldrick LL, Singh AK, Saotome K, Yelshanskaya MV, Twomey EC, Grassucci RA, Sobolevsky AI. Opening of the human epithelial calcium channel TRPV6. Nature 2017; 553:233-237. [PMID: 29258289 PMCID: PMC5854407 DOI: 10.1038/nature25182] [Citation(s) in RCA: 150] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 11/28/2017] [Indexed: 12/18/2022]
Abstract
Ca2+-selective transient receptor potential vanilloid subfamily member 6 (TRPV6) channels play a critical role in calcium uptake in epithelial tissues1–4. Altered TRPV6 expression is associated with a variety of human diseases5, including cancers6. TRPV6 channels are constitutively active1,7,8 and their open probability depends on the lipidic composition of the membrane, increasing significantly in the presence of phosphatidylinositol 4,5-bisphosphate (PIP2)7,9. We previously solved crystal structures of detergent-solubilized rat TRPV6 in the closed state10,11. Corroborating previous electrophysiological studies3, these structures demonstrated that the Ca2+ selectivity of TRPV6 arises from a ring of aspartate side chains in the selectivity filter that tightly binds Ca2+. However, it has remained unknown how TRPV6 channels open and close their pores for ion permeation. Here we present cryo-EM structures of human TRPV6 in the open and closed states. The channel selectivity filter adopts similar conformations in both states, consistent with its explicit role in ion permeation. The iris-like channel opening is accompanied by an α-to-π helical transition in the pore-lining S6 helices at an alanine hinge just below the selectivity filter. As a result of this transition, the S6 helices bend and rotate, exposing different residues to the ion channel pore in the open and closed states. This novel gating mechanism, which defines the constitutive activity of TRPV6, is unique for tetrameric ion channels and provides new structural insights for understanding their diverse roles in physiology and disease.
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Affiliation(s)
- Luke L McGoldrick
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, New York 10032, USA.,Integrated Program in Cellular, Molecular, and Biomedical Studies, Columbia University, 650 West 168th Street, New York, New York 10032, USA
| | - Appu K Singh
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, New York 10032, USA
| | - Kei Saotome
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, New York 10032, USA
| | - Maria V Yelshanskaya
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, New York 10032, USA
| | - Edward C Twomey
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, New York 10032, USA.,Integrated Program in Cellular, Molecular, and Biomedical Studies, Columbia University, 650 West 168th Street, New York, New York 10032, USA
| | - Robert A Grassucci
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, New York 10032, USA
| | - Alexander I Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, New York 10032, USA
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23
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Fleet JC. The role of vitamin D in the endocrinology controlling calcium homeostasis. Mol Cell Endocrinol 2017; 453:36-45. [PMID: 28400273 PMCID: PMC5529228 DOI: 10.1016/j.mce.2017.04.008] [Citation(s) in RCA: 157] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 04/07/2017] [Accepted: 04/08/2017] [Indexed: 12/14/2022]
Abstract
Vitamin D and its' metabolites are a crucial part of the endocrine system that controls whole body calcium homeostasis. The goal of this hormonal control is to regulate serum calcium levels so that they are maintained within a very narrow range. To achieve this goal, regulatory events occur in coordination at multiple tissues, e.g. the intestine, kidney, bone, and parathyroid gland. Production of the vitamin D endocrine hormone, 1,25 dihydroxyvitamin D (1,25(OH)2 D) is regulated by habitual dietary calcium intake and physiologic states like growth, aging, and the menopause. The molecular actions of 1,25(OH)2 D on calcium regulating target tissues are mediated predominantly by transcription controlled by the vitamin D receptor. A primary role for 1,25(OH)2 D during growth is to increase intestinal calcium absorption so that sufficient calcium is available for bone mineralization. However, vitamin D also has specific actions on kidney and bone.
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Affiliation(s)
- James C Fleet
- Department of Nutrition Science, Room G1B Stone Hall, Purdue University, West Lafayette, IN 47907-2059, United States.
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Bastepe M, Turan S, He Q. Heterotrimeric G proteins in the control of parathyroid hormone actions. J Mol Endocrinol 2017; 58:R203-R224. [PMID: 28363951 PMCID: PMC5650080 DOI: 10.1530/jme-16-0221] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 02/17/2017] [Indexed: 12/17/2022]
Abstract
Parathyroid hormone (PTH) is a key regulator of skeletal physiology and calcium and phosphate homeostasis. It acts on bone and kidney to stimulate bone turnover, increase the circulating levels of 1,25 dihydroxyvitamin D and calcium and inhibit the reabsorption of phosphate from the glomerular filtrate. Dysregulated PTH actions contribute to or are the cause of several endocrine disorders. This calciotropic hormone exerts its actions via binding to the PTH/PTH-related peptide receptor (PTH1R), which couples to multiple heterotrimeric G proteins, including Gs and Gq/11 Genetic mutations affecting the activity or expression of the alpha-subunit of Gs, encoded by the GNAS complex locus, are responsible for several human diseases for which the clinical findings result, at least partly, from aberrant PTH signaling. Here, we review the bone and renal actions of PTH with respect to the different signaling pathways downstream of these G proteins, as well as the disorders caused by GNAS mutations.
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Affiliation(s)
- Murat Bastepe
- Endocrine UnitDepartment of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Serap Turan
- Department of Pediatric EndocrinologyMarmara University School of Medicine, Istanbul, Turkey
| | - Qing He
- Endocrine UnitDepartment of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
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Mohammed SG, Arjona FJ, Latta F, Bindels RJM, Roepman R, Hoenderop JGJ. Fluid shear stress increases transepithelial transport of Ca
2+
in ciliated distal convoluted and connecting tubule cells. FASEB J 2017; 31:1796-1806. [DOI: 10.1096/fj.201600687rrr] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 01/03/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Sami G. Mohammed
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - Francisco J. Arjona
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - Femke Latta
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - René J. M. Bindels
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - Ronald Roepman
- Department of Human GeneticsRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - Joost G. J. Hoenderop
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
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Sun F, Xiao L, Jang XX, Xiong Y, Li Q, Yue XJ, Wei YJ, Wei YX, Ma YL, Yu YH. TRPV6 is a prognostic marker in early-stage cervical squamous cell carcinoma. Tumour Biol 2016; 37:10.1007/s13277-016-5368-4. [PMID: 27747588 DOI: 10.1007/s13277-016-5368-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 09/07/2016] [Indexed: 10/20/2022] Open
Abstract
Transient receptor potential vanilloid 6 (TRPV6) has been shown to promote caner proliferation in several solid tumors, leading to unfavorable clinical outcomes. Our study aimed to elucidate the clinical significance of TRPV6 in patients with early-stage cervical squamous cell carcinoma (CSCC). The mRNA expression of TRPV6 was measured in 12 paired early-stage CSCC specimens and six cervical carcinoma cell lines using quantitative real-time PCR (qRT-PCR). Western blotting and immunohistochemistry (IHC) were employed to examine the protein expression level of TRPV6 in four paired specimens, 175 paraffin-embedded early-stage CSCC specimens, and 50 normal cervical tissues (NCTs), respectively. Statistical analyses were performed to evaluate the clinical significance of TRPV6 expression. The expressions of TRPV6 mRNA and protein were both significantly downregulated in early-stage CSCC tissues and cervical cancer cell lines. IHC analyses revealed that TRPV6 was downregulated in 136 (77.7 %) of 175 early-stage CSCC specimens. Moreover, TRPV6 expression in early-stage CSCC was significantly correlated with the tumor stage (P < 0.001), tumor growth type (P < 0.001), tumor size (P = 0.008), and differentiation grade (P = 0.003). The early-stage CSCC patients with a low TRPV6 expression level had a short progress-free survival (PFS) and overall survival (OS) duration. Univariate and multivariate analyses identified TRPV6 as an independent prognostic factor for early-stage CSCC patients' survival. We demonstrated that TRPV6 was downregulated in CSCC, which was correlated with unfavorable survival outcomes of early-stage CSCC patients. TRPV6 may be used as a novel prognostic marker for early-stage CSCC.
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Affiliation(s)
- Fei Sun
- Department of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, 1838 North Guangzhou Ave, Guangdong, People's Republic of China, 510515
| | - Lu Xiao
- Department of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, 1838 North Guangzhou Ave, Guangdong, People's Republic of China, 510515
| | - Xin-Xing Jang
- Hainan Provincial Key Laboratory for Human Reproductive Medicine and Genetic Research, Affiliated Hospital of Hainan Medical University, Hainan Medical University, Haikou, Hainan, 571101, China
| | - Ying Xiong
- Department of Gynecologic Oncology, Sun Yat-sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, People's Republic of China, 510060
| | - Qi Li
- Hainan Provincial Key Laboratory for Human Reproductive Medicine and Genetic Research, Affiliated Hospital of Hainan Medical University, Hainan Medical University, Haikou, Hainan, 571101, China
| | - Xiao-Jing Yue
- Department of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, 1838 North Guangzhou Ave, Guangdong, People's Republic of China, 510515
| | - Yun-Jian Wei
- Hainan Provincial Key Laboratory for Human Reproductive Medicine and Genetic Research, Affiliated Hospital of Hainan Medical University, Hainan Medical University, Haikou, Hainan, 571101, China
| | - Yan-Xing Wei
- Department of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, 1838 North Guangzhou Ave, Guangdong, People's Republic of China, 510515
| | - Yan-Lin Ma
- Department of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, 1838 North Guangzhou Ave, Guangdong, People's Republic of China, 510515.
- Hainan Provincial Key Laboratory for Human Reproductive Medicine and Genetic Research, Affiliated Hospital of Hainan Medical University, Hainan Medical University, Haikou, Hainan, 571101, China.
| | - Yan-Hong Yu
- Department of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, 1838 North Guangzhou Ave, Guangdong, People's Republic of China, 510515.
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Azarpeykan S, Dittmer KE, Marshall JC, Perera KC, Gee EK, Acke E, Thompson KG. Evaluation and Comparison of Vitamin D Responsive Gene Expression in Ovine, Canine and Equine Kidney. PLoS One 2016; 11:e0162598. [PMID: 27632366 PMCID: PMC5025205 DOI: 10.1371/journal.pone.0162598] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 08/25/2016] [Indexed: 01/15/2023] Open
Abstract
The aim of this study was to determine the relative abundance and relationship of vitamin D responsive and calcium transporting transcripts (TRPV5, TRPV6, calD9k, calD28k, PMCA, NCX1, CYP27B1, CYP24A1, and VDR) in ovine, canine and, equine kidney using quantitative real-time PCR (RT-qPCR), and then perform a comparison between the three species. Renal tissue samples were harvested post-mortem from 10 horses, 10 sheep, and five dogs. Primers were designed for each gene. For each sample total RNA was extracted, cDNA synthesised, and RT-qPCR was performed. RT-qPCR data were normalised and statistical comparison was performed. Due to their consistent correlation with each other in each species, TRPV6, calD9k/calD28k, and PMCA appeared to be the main pathways involved in active transepithelial calcium transport in the kidney of sheep, dogs and horses. The results indicate that all of the studied genes were expressed in the renal tissue of studied species, although the expression levels and correlation of transcripts with each other were different from species to species. All vitamin D responsive and calcium transporting transcripts were highly correlated with VDR in equine kidney, but not in sheep and dogs. The CYP27B1 and CYP24A1 mRNAs showed a different renal expression pattern and correlation in horses compared with sheep and dogs. Given the high urinary calcium concentration and low serum 1,25(OH)2D concentration in horses, it could be expected that CYP27B1 expression would be lower than CYP24A1 in the horse, and this did not appear to be the case. The findings suggest that despite low serum vitamin D concentrations, vitamin D still plays a significant role in calcium metabolism in horses, especially given the strong correlations between VDR and vitamin D responsive transcripts in these animals.
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Affiliation(s)
- Sara Azarpeykan
- Institute of Veterinary, Animal and Biomedical Science (IVABS), Massey University, Palmerston North, New Zealand
- * E-mail:
| | - Keren E. Dittmer
- Institute of Veterinary, Animal and Biomedical Science (IVABS), Massey University, Palmerston North, New Zealand
| | - Jonathan C. Marshall
- Institute of Fundamental Sciences (IFS), Massey University, Palmerston North, New Zealand
| | - Kalyani C. Perera
- Institute of Veterinary, Animal and Biomedical Science (IVABS), Massey University, Palmerston North, New Zealand
| | - Erica K. Gee
- Institute of Veterinary, Animal and Biomedical Science (IVABS), Massey University, Palmerston North, New Zealand
| | - Els Acke
- Institute of Veterinary, Animal and Biomedical Science (IVABS), Massey University, Palmerston North, New Zealand
| | - Keith G. Thompson
- Institute of Veterinary, Animal and Biomedical Science (IVABS), Massey University, Palmerston North, New Zealand
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Cantero MDR, Cantiello HF. Polycystin-2 (TRPP2) Regulation by Ca(2+) Is Effected and Diversified by Actin-Binding Proteins. Biophys J 2016; 108:2191-200. [PMID: 25954877 DOI: 10.1016/j.bpj.2015.03.050] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 03/14/2015] [Accepted: 03/26/2015] [Indexed: 12/13/2022] Open
Abstract
Calcium regulation of Ca(2+)-permeable ion channels is an important mechanism in the control of cell function. Polycystin-2 (PC2, TRPP2), a member of the transient receptor potential superfamily, is a nonselective cation channel with Ca(2+) permeability. The molecular mechanisms associated with PC2 regulation by Ca(2+) remain ill-defined. We recently demonstrated that PC2 from human syncytiotrophoblast (PC2hst) but not the in vitro translated protein (PC2(iv)), functionally responds to changes in intracellular (cis) Ca(2+). In this study we determined the regulatory effect(s) of Ca(2+)-sensitive and -insensitive actin-binding proteins (ABPs) on PC2(iv) channel function in a lipid bilayer system. The actin-bundling protein α-actinin increased PC2(iv) channel function in the presence of cis Ca(2+), although instead was inhibitory in its absence. Conversely, filamin that shares actin-binding domains with α-actinin had a strong inhibitory effect on PC2(iv) channel function in the presence, but no effect in the absence of cis Ca(2+). Gelsolin stimulated PC2(iv) channel function in the presence, but not the absence of cis Ca(2+). In contrast, profilin that shares actin-binding domains with gelsolin, significantly increased PC2(iv) channel function both in the presence and absence of Ca(2+). The distinct effect(s) of the ABPs on PC2(iv) channel function demonstrate that Ca(2+) regulation of PC2 is actually mediated by direct interaction(s) with structural elements of the actin cytoskeleton. These data indicate that specific ABP-PC2 complexes would confer distinct Ca(2+)-sensitive properties to the channel providing functional diversity to the cytoskeletal control of transient receptor potential channel regulation.
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Affiliation(s)
- María del Rocío Cantero
- Cátedra de Biofísica, Facultad de Odontología, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
| | - Horacio F Cantiello
- Cátedra de Biofísica, Facultad de Odontología, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina.
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Zhang SS, Xie X, Wen J, Luo KJ, Liu QW, Yang H, Hu Y, Fu JH. TRPV6 plays a new role in predicting survival of patients with esophageal squamous cell carcinoma. Diagn Pathol 2016; 11:14. [PMID: 26818094 PMCID: PMC4730645 DOI: 10.1186/s13000-016-0457-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 01/14/2016] [Indexed: 12/26/2022] Open
Abstract
Background TRPV6 is over-expressed and promotes the proliferation and invasion in many cancers. The association between the expression of TRPV6 and clinical outcome in esophageal squamous cell carcinoma (ESCC) has not been studied yet. We aim to elucidate the role of TRPV6 in predicting prognosis of patients with ESCC. Methods In the retrospective study, mRNA level of TRPV6 was examined in patients (N = 174) from Sun Yat-sen University Cancer Center (mRNA cohort) and protein level of TRPV6 was examined in patients (N = 218) from Linzhou Cancer Hospital (protein cohort). Statistical analysis was performed to test the clinical and prognostic significance of TRPV6. Results TRPV6 was down-regulated in ESCC tissues and cell lines. Patients with downregulation of TRPV6 trended to have a higher rate of advanced pT stage in both mRNA cohort (P = 0.089) and protein cohort (P = 0.073), though not statistically significant. No significant association was observed between TRPV6 expression and disease-specific survival (DSS) in both two cohorts. However, stratified survival analysis based on the gender showed that in mRNA cohort, downregulation of TRPV6 was associated with an unfavorable 3-year DSS in patients with male (47.3 % vs 63.6 %, P = 0.027) and with favorable 3-year DSS in patients with female (66.7 % vs 43.0 %, P = 0.031). The result was confirmed in protein cohort. Male patients with downregulation of TRPV6 had a poor 3-year DSS (20.0 % vs 57.1 %,P < 0.001) while female counterparts showed an enhanced 3-year DSS (56.1 % vs 28.6 %, P = 0.005). Conclusion TRPV6 is down-regulated in ESCC. As a predictive biomarker, TRPV6 plays a Janus-like role in predicting survival of male and female ESCC patients.
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Affiliation(s)
- Shui-Shen Zhang
- State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, People's Republic of China. .,Guangdong Esophageal Cancer Research Institute, Guangzhou, People's Republic of China. .,Department of Thoracic Oncology, Sun Yat-Sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, 510060, People's Republic of China. .,Department of Thoracic Surgery, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, People's Republic of China.
| | - Xuan Xie
- Department of Thoracic Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, People's Republic of China.
| | - Jing Wen
- State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, People's Republic of China. .,Guangdong Esophageal Cancer Research Institute, Guangzhou, People's Republic of China. .,Department of Thoracic Oncology, Sun Yat-Sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, 510060, People's Republic of China.
| | - Kong-Jia Luo
- State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, People's Republic of China. .,Guangdong Esophageal Cancer Research Institute, Guangzhou, People's Republic of China. .,Department of Thoracic Oncology, Sun Yat-Sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, 510060, People's Republic of China.
| | - Qian-Wen Liu
- State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, People's Republic of China. .,Guangdong Esophageal Cancer Research Institute, Guangzhou, People's Republic of China. .,Department of Thoracic Oncology, Sun Yat-Sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, 510060, People's Republic of China.
| | - Hong Yang
- State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, People's Republic of China. .,Guangdong Esophageal Cancer Research Institute, Guangzhou, People's Republic of China. .,Department of Thoracic Oncology, Sun Yat-Sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, 510060, People's Republic of China.
| | - Yi Hu
- State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, People's Republic of China. .,Guangdong Esophageal Cancer Research Institute, Guangzhou, People's Republic of China. .,Department of Thoracic Oncology, Sun Yat-Sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, 510060, People's Republic of China.
| | - Jian-Hua Fu
- State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, People's Republic of China. .,Guangdong Esophageal Cancer Research Institute, Guangzhou, People's Republic of China. .,Department of Thoracic Oncology, Sun Yat-Sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, 510060, People's Republic of China.
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Hoover RS, Tomilin V, Hanson L, Pochynyuk O, Ko B. PTH modulation of NCC activity regulates TRPV5 Ca2+ reabsorption. Am J Physiol Renal Physiol 2015; 310:F144-51. [PMID: 26608788 DOI: 10.1152/ajprenal.00323.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 11/24/2015] [Indexed: 02/02/2023] Open
Abstract
Since parathyroid hormone (PTH) is known to increase transient receptor potential vanilloid (TRPV)5 activity and decrease Na(+)-Cl(-) cotransporter (NCC) activity, we hypothesized that decreased NCC-mediated Na(+) reabsorption contributes to the enhanced TRPV5 Ca(2+) reabsorption seen with PTH. To test this, we used mDCT15 cells expressing functional TRPV5 and ruthenium red-sensitive (45)Ca(2+) uptake. PTH increased (45)Ca(2+) uptake to 8.8 ± 0.7 nmol·mg(-1)·min(-1) (n = 4, P < 0.01) and decreased NCC activity from 75.4 ± 2.7 to 20.3 ± 1.3 nmol·mg(-1)·min(-1) (n = 4, P < 0.01). Knockdown of Ras guanyl-releasing protein (RasGRP)1 had no baseline effect on (45)Ca(2+) uptake but significantly attenuated the response to PTH from a 45% increase (6.0 ± 0.2 to 8.7 ± 0.4 nmol·mg(-1)·min(-1)) in control cells to only 20% in knockdown cells (6.1 ± 0.1 to 7.3 ± 0.2 nmol·mg(-1)·min(-1), n = 4, P < 0.01). Inhibition of PKC and PKA resulted in further attenuation of the PTH effect. RasGRP1 knockdown decreased the magnitude of the TRPV5 response to PTH (7.9 ± 0.1 nmol·mg(-1)·min(-1) for knockdown compared with 9.1 ± 0.1 nmol·mg(-1)·min(-1) in control), and the addition of thiazide eliminated this effect (a nearly identical 9.0 ± 0.1 nmol·mg(-1)·min(-1)). This indicates that functionally active NCC is required for RasGRP1 knockdown to impact the PTH effect on TRPV5 activity. Knockdown of with no lysine kinase (WNK)4 resulted in an attenuation of the increase in PTH-mediated TRPV5 activity. TRPV5 activity increased by 36% compared with 45% in control (n = 4, P < 0.01 between PTH-treated groups). PKC blockade further attenuated the PTH effect, whereas combined PKC and PKA blockade in WNK4KD cells abolished the effect. We conclude that modulation of NCC activity contributes to the response to PTH, implying a role for hormonal modulation of NCC activity in distal Ca(2+) handling.
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Affiliation(s)
- Robert S Hoover
- Division of Nephrology, Department of Medicine, Emory University, Atlanta, Georgia; Atlanta Veteran's Administration Medical Center, Decatur, Georgia
| | - Viktor Tomilin
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center, Houston, Texas; Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russian Federation; and
| | - Lauren Hanson
- Department of Medicine, University of Chicago, Chicago, Illinois
| | - Oleh Pochynyuk
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center, Houston, Texas
| | - Benjamin Ko
- Department of Medicine, University of Chicago, Chicago, Illinois
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Diaz de Barboza G, Guizzardi S, Tolosa de Talamoni N. Molecular aspects of intestinal calcium absorption. World J Gastroenterol 2015; 21:7142-7154. [PMID: 26109800 PMCID: PMC4476875 DOI: 10.3748/wjg.v21.i23.7142] [Citation(s) in RCA: 134] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/21/2015] [Accepted: 04/17/2015] [Indexed: 02/06/2023] Open
Abstract
Intestinal Ca2+ absorption is a crucial physiological process for maintaining bone mineralization and Ca2+ homeostasis. It occurs through the transcellular and paracellular pathways. The first route comprises 3 steps: the entrance of Ca2+ across the brush border membranes (BBM) of enterocytes through epithelial Ca2+ channels TRPV6, TRPV5, and Cav1.3; Ca2+ movement from the BBM to the basolateral membranes by binding proteins with high Ca2+ affinity (such as CB9k); and Ca2+ extrusion into the blood. Plasma membrane Ca2+ ATPase (PMCA1b) and sodium calcium exchanger (NCX1) are mainly involved in the exit of Ca2+ from enterocytes. A novel molecule, the 4.1R protein, seems to be a partner of PMCA1b, since both molecules co-localize and interact. The paracellular pathway consists of Ca2+ transport through transmembrane proteins of tight junction structures, such as claudins 2, 12, and 15. There is evidence of crosstalk between the transcellular and paracellular pathways in intestinal Ca2+ transport. When intestinal oxidative stress is triggered, there is a decrease in the expression of several molecules of both pathways that inhibit intestinal Ca2+ absorption. Normalization of redox status in the intestine with drugs such as quercetin, ursodeoxycholic acid, or melatonin return intestinal Ca2+ transport to control values. Calcitriol [1,25(OH)2D3] is the major controlling hormone of intestinal Ca2+ transport. It increases the gene and protein expression of most of the molecules involved in both pathways. PTH, thyroid hormones, estrogens, prolactin, growth hormone, and glucocorticoids apparently also regulate Ca2+ transport by direct action, indirect mechanism mediated by the increase of renal 1,25(OH)2D3 production, or both. Different physiological conditions, such as growth, pregnancy, lactation, and aging, adjust intestinal Ca2+ absorption according to Ca2+ demands. Better knowledge of the molecular details of intestinal Ca2+ absorption could lead to the development of nutritional and medical strategies for optimizing the efficiency of intestinal Ca2+ absorption and preventing osteoporosis and other pathologies related to Ca2+ metabolism.
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Giusti L, Cetani F, Da Valle Y, Pardi E, Ciregia F, Donadio E, Gargini C, Piano I, Borsari S, Jaber A, Caputo A, Basolo F, Giannaccini G, Marcocci C, Lucacchini A. First evidence of TRPV5 and TRPV6 channels in human parathyroid glands: possible involvement in neoplastic transformation. J Cell Mol Med 2014; 18:1944-52. [PMID: 25164318 PMCID: PMC4244010 DOI: 10.1111/jcmm.12372] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 06/12/2014] [Indexed: 11/27/2022] Open
Abstract
The parathyroid glands play an overall regulatory role in the systemic calcium (Ca2+) homeostasis. The purpose of the present study was to demonstrate the presence of the Ca2+ channels transient receptor potential vanilloid (TRPV) 5 and TRPV6 in human parathyroid glands. Semi-quantitative and quantitative PCR was carried out to evaluate the presence of TRPV5 and TRPV6 mRNAs in sporadic parathyroid adenomas and normal parathyroid glands. Western blot and immunocytochemical assays were used to assess protein expression, cellular localization and time expression in primary cultures from human parathyroid adenoma. TRPV5 and TRPV6 transcripts were then identified both in normal and pathological tissues. Predominant immunoreactive bands were detected at 75–80 kD for both vanilloid channels. These channels co-localized with the calcium-sensing receptor (CASR) on the membrane surface, but immunoreactivity was also detected in the cytosol and around the nuclei. Our data showed that western blotting recorded an increase of protein expression of both channels in adenoma samples compared with normal glands suggesting a potential relation with the cell calcium signalling pathway and the pathological processes of these glands.
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Affiliation(s)
- Laura Giusti
- Department of Pharmacy, University of Pisa, Pisa, Italy
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Permeation, regulation and control of expression of TRP channels by trace metal ions. Pflugers Arch 2014; 467:1143-64. [PMID: 25106481 PMCID: PMC4435931 DOI: 10.1007/s00424-014-1590-3] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 07/10/2014] [Accepted: 07/13/2014] [Indexed: 01/26/2023]
Abstract
Transient receptor potential (TRP) channels form a diverse family of cation channels comprising 28 members in mammals. Although some TRP proteins can only be found on intracellular membranes, most of the TRP protein isoforms reach the plasma membrane where they form ion channels and control a wide number of biological processes. There, their involvement in the transport of cations such as calcium and sodium has been well documented. However, a growing number of studies have started to expand our understanding of these proteins by showing that they also transport other biologically relevant metal ions like zinc, magnesium, manganese and cobalt. In addition to this newly recognized property, the activity and expression of TRP channels can be regulated by metal ions like magnesium, gadolinium, lanthanum or cisplatin. The aim of this review is to highlight the complex relationship between metal ions and TRP channels.
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Montalbetti N, Dalghi MG, Albrecht C, Hediger MA. Nutrient transport in the mammary gland: calcium, trace minerals and water soluble vitamins. J Mammary Gland Biol Neoplasia 2014; 19:73-90. [PMID: 24567109 DOI: 10.1007/s10911-014-9317-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 01/22/2014] [Indexed: 01/19/2023] Open
Abstract
Milk nutrients are secreted by epithelial cells in the alveoli of the mammary gland by several complex and highly coordinated systems. Many of these nutrients are transported from the blood to the milk via transcellular pathways that involve the concerted activity of transport proteins on the apical and basolateral membranes of mammary epithelial cells. In this review, we focus on transport mechanisms that contribute to the secretion of calcium, trace minerals and water soluble vitamins into milk with particular focus on the role of transporters of the SLC series as well as calcium transport proteins (ion channels and pumps). Numerous members of the SLC family are involved in the regulation of essential nutrients in the milk, such as the divalent metal transporter-1 (SLC11A2), ferroportin-1 (SLC40A1) and the copper transporter CTR1 (SLC31A1). A deeper understanding of the physiology and pathophysiology of these transporters will be of great value for drug discovery and treatment of breast diseases.
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Affiliation(s)
- Nicolas Montalbetti
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research, NCCR TransCure, University of Bern, Bühlstrasse 28, 3012, Bern, Switzerland,
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Cantero MDR, Cantiello HF. Calcium transport and local pool regulate polycystin-2 (TRPP2) function in human syncytiotrophoblast. Biophys J 2014; 105:365-75. [PMID: 23870258 DOI: 10.1016/j.bpj.2013.05.058] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 05/16/2013] [Accepted: 05/30/2013] [Indexed: 01/26/2023] Open
Abstract
Polycystin-2 (PC2, TRPP2) is a Ca(2+)-permeable, nonselective cation channel implicated in Ca(2+) transport and epithelial cell signaling. Although PC2 may contribute to Ca(2+) transport in human term placenta, the regulatory mechanisms associated with Ca(2+) handling in this tissue are largely unknown. In this work we assessed the regulation by Ca(2+) of PC2 channel function from a preparation of apical membranes of human syncytiotrophoblast (PC2hst) reconstituted in a lipid bilayer system. Addition of either EGTA or BAPTA to the cis hemi-chamber, representing the cytoplasmic domain of the channel, and lowering Ca(2+) to ∼0.6-0.8 nM, inhibited spontaneous PC2hst channel activity, with a time response dependent on the chelator tested. EGTA reduced PC2hst channel currents by 86%, with a t1/2 = 3.6 min, whereas BAPTA rapidly and completely (100%) eliminated channel activity with a t1/2 = 0.8 min. Subsequent titration with Ca(2+) reversed the inhibition, which followed a Hill-type function with apparent dissociation constants of 1-5 nM, and 4 Ca(2+) binding sites. The degree of inhibition by the cis Ca(2+) chelator largely depended on increasing trans Ca(2+). This was consistent with measurable Ca(2+) transport through the channel, feeding the regulatory sites in the cytoplasmic domain. Interestingly, the reconstituted in vitro translated PC2 (PC2iv) was completely insensitive to Ca(2+) regulation, suggesting that the regulatory sites are not intrinsic to the channel protein. Our findings demonstrate the presence of a Ca(2+) microdomain largely accessible through the channel that controls PC2 function in human syncytiotrophoblast of term placenta.
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Affiliation(s)
- María Del Rocío Cantero
- Cátedra de Biofísica, Facultad de Odontología, Universidad de Buenos Aires, Buenos Aires, Argentina
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Andrukhova O, Smorodchenko A, Egerbacher M, Streicher C, Zeitz U, Goetz R, Shalhoub V, Mohammadi M, Pohl EE, Lanske B, Erben RG. FGF23 promotes renal calcium reabsorption through the TRPV5 channel. EMBO J 2014; 33:229-46. [PMID: 24434184 PMCID: PMC3983685 DOI: 10.1002/embj.201284188] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
αKlotho is thought to activate the epithelial calcium channel Transient Receptor Potential Vanilloid-5 (TRPV5) in distal renal tubules through its putative glucuronidase/sialidase activity, thereby preventing renal calcium loss. However, αKlotho also functions as the obligatory co-receptor for fibroblast growth factor-23 (FGF23), a bone-derived phosphaturic hormone. Here, we show that renal calcium reabsorption and renal membrane abundance of TRPV5 are reduced in Fgf23 knockout mice, similar to what is seen in αKlotho knockout mice. We further demonstrate that αKlotho neither co-localizes with TRPV5 nor is regulated by FGF23. Rather, apical membrane abundance of TRPV5 in renal distal tubules and thus renal calcium reabsorption are regulated by FGF23, which binds the FGF receptor-αKlotho complex and activates a signaling cascade involving ERK1/2, SGK1, and WNK4. Our data thereby identify FGF23, not αKlotho, as a calcium-conserving hormone in the kidney.
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Abstract
TRP channels constitute a large superfamily of cation channel forming proteins, all related to the gene product of the transient receptor potential (trp) locus in Drosophila. In mammals, 28 different TRP channel genes have been identified, which exhibit a large variety of functional properties and play diverse cellular and physiological roles. In this article, we provide a brief and systematic summary of expression, function, and (patho)physiological role of the mammalian TRP channels.
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Affiliation(s)
- Maarten Gees
- Laboratory Ion Channel Research and TRP Research Platform Leuven (TRPLe), KU Leuven, Campus Gasthuisberg, Leuven, Belgium
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Courjaret R, Hubrack S, Daalis A, Dib M, Machaca K. The
Xenopus
TRPV6 homolog encodes a Mg
2+
‐permeant channel that is inhibited by interaction with TRPC1. J Cell Physiol 2013; 228:2386-98. [DOI: 10.1002/jcp.24411] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 05/21/2013] [Indexed: 01/29/2023]
Affiliation(s)
- Raphael Courjaret
- Department of Physiology and BiophysicsWeill Cornell Medical College in QatarEducation City, Qatar FoundationDohaQatar
| | - Satanay Hubrack
- Department of Physiology and BiophysicsWeill Cornell Medical College in QatarEducation City, Qatar FoundationDohaQatar
| | - Arwa Daalis
- Department of Physiology and BiophysicsWeill Cornell Medical College in QatarEducation City, Qatar FoundationDohaQatar
| | - Maya Dib
- Department of Physiology and BiophysicsWeill Cornell Medical College in QatarEducation City, Qatar FoundationDohaQatar
| | - Khaled Machaca
- Department of Physiology and BiophysicsWeill Cornell Medical College in QatarEducation City, Qatar FoundationDohaQatar
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Leunissen EHP, Nair AV, Büll C, Lefeber DJ, van Delft FL, Bindels RJM, Hoenderop JGJ. The epithelial calcium channel TRPV5 is regulated differentially by klotho and sialidase. J Biol Chem 2013; 288:29238-46. [PMID: 23970553 DOI: 10.1074/jbc.m113.473520] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The transient receptor potential vanilloid type 5 (TRPV5) Ca(2+) channel facilitates transcellular Ca(2+) transport in the distal convoluted tubule (DCT) of the kidney. The channel is glycosylated with a complex type N-glycan and it has been postulated that hydrolysis of the terminal sialic acid(s) stimulate TRPV5 activity. The present study delineates the role of the N-glycan in TRPV5 activity using biochemical assays in Human Embryonic Kidney 293 cells expressing TRPV5, isoelectric focusing and total internal reflection fluorescent microscopy. The anti-aging hormone klotho and other glycosidases stimulate TRPV5-dependent Ca(2+) uptake. Klotho was found to increase the plasma membrane stability of TRPV5, via the TRPV5 N-glycan. Sialidase mimicked this stimulatory action. However, this effect was independent of the N-glycosylation state of TRPV5, since the N-glycosylation mutant (TRPV5(N358Q)) was activated to the same extent. We showed that the increased TRPV5 activity after sialidase treatment is caused by inhibition of lipid raft-mediated internalization. In addition, sialidase modified the N-glycan of transferrin, a model glycoprotein, differently from klotho. Previous studies showed that after klotho treatment, galectin-1 binds the TRPV5 N-glycan and thereby increases TRPV5 activity. However, galectin-3, but not galectin-1, was expressed in the DCT. Furthermore, an increase in TRPV5-mediated Ca(2+) uptake was detected after galectin-3 treatment. In conclusion, two distinct TRPV5 stimulatory mechanisms were demonstrated; a klotho-mediated effect that is dependent on the N-glycan of TRPV5 and a sialidase-mediated stimulation that is lipid raft-dependent and independent of the N-glycan of TRPV5.
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Rievaj J, Pan W, Cordat E, Alexander RT. The Na⁺/H⁺ exchanger isoform 3 is required for active paracellular and transcellular Ca²⁺ transport across murine cecum. Am J Physiol Gastrointest Liver Physiol 2013; 305:G303-13. [PMID: 23764894 PMCID: PMC4959879 DOI: 10.1152/ajpgi.00490.2012] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Intestinal calcium (Ca²⁺) absorption occurs via paracellular and transcellular pathways. Although the transcellular route has been extensively studied, mechanisms mediating paracellular absorption are largely unexplored. Unlike passive diffusion, secondarily active paracellular Ca²⁺ uptake occurs against an electrochemical gradient with water flux providing the driving force. Water movement is dictated by concentration differences that are largely determined by Na⁺ fluxes. Consequently, we hypothesized that Na⁺ absorption mediates Ca²⁺ flux. NHE3 is central to intestinal Na⁺ absorption. NHE3 knockout mice (NHE3-/-) display impaired intestinal Na⁺, water, and Ca²⁺ absorption. However, the mechanism mediating this latter abnormality is not clear. To investigate this, we used Ussing chambers to measure net Ca²⁺ absorption across different segments of wild-type mouse intestine. The cecum was the only segment with net Ca²⁺ absorption. Quantitative RT-PCR measurements revealed cecal expression of all genes implicated in intestinal Ca²⁺ absorption, including NHE3. We therefore employed this segment for further studies. Inhibition of NHE3 with 100 μM 5-(N-ethyl-N-isopropyl) amiloride decreased luminal-to-serosal and increased serosal-to-luminal Ca²⁺ flux. NHE3-/- mice had a >60% decrease in luminal-to-serosal Ca²⁺ flux. Ussing chambers experiments under altered voltage clamps (-25, 0, +25 mV) showed decreased transcellular and secondarily active paracellular Ca²⁺ absorption in NHE3-/- mice relative to wild-type animals. Consistent with this, cecal Trpv6 expression was diminished in NHE3-/- mice. Together these results implicate NHE3 in intestinal Ca(2+) absorption and support the theory that this is, at least partially, due to the role of NHE3 in Na⁺ and water absorption.
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Affiliation(s)
- Juraj Rievaj
- Dept. of Pediatrics, 4-585 Edmonton Clinic Health Academy, 11405 87th Ave., Univ. of Alberta, Edmonton, Alberta, T6G 2R7, Canada.
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Guo Z, Grimm C, Becker L, Ricci AJ, Heller S. A novel ion channel formed by interaction of TRPML3 with TRPV5. PLoS One 2013; 8:e58174. [PMID: 23469151 PMCID: PMC3585263 DOI: 10.1371/journal.pone.0058174] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 01/31/2013] [Indexed: 01/15/2023] Open
Abstract
TRPML3 and TRPV5 are members of the mucolipin (TRPML) and TRPV subfamilies of transient receptor potential (TRP) cation channels. Based on sequence similarities of the pore forming regions and on structure-function evidence, we hypothesized that the pore forming domains of TRPML and TRPV5/TRPV6 channels have similarities that indicate possible functional interactions between these TRP channel subfamilies. Here we show that TRPML3 and TRPV5 associate to form a novel heteromeric ion channel. This novel conductance is detectable under conditions that do not activate either TRPML3 or TRPV5. It has pharmacological similarity with TRPML3 and requires functional TRPML3 as well as functional TRPV5. Single channel analyses revealed that TRPML3 and TRPV5 heteromers have different features than the respective homomers, and furthermore, that they occur in potentially distinct stoichiometric configurations. Based on overlapping expression of TRPML3 and TRPV5 in the kidney and the inner ear, we propose that TRPML3 and TRPV5 heteromers could have a biological function in these organs.
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Affiliation(s)
- Zhaohua Guo
- Departments of Otolaryngology – HNS and Molecular & Cellular Physiology, Stanford University School of Medicine, Palo Alto, California, United States of America
| | - Christian Grimm
- Department of Pharmacy – Center for Drug Research and Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität, München, Germany
| | - Lars Becker
- Departments of Otolaryngology – HNS and Molecular & Cellular Physiology, Stanford University School of Medicine, Palo Alto, California, United States of America
| | - Anthony J. Ricci
- Departments of Otolaryngology – HNS and Molecular & Cellular Physiology, Stanford University School of Medicine, Palo Alto, California, United States of America
| | - Stefan Heller
- Departments of Otolaryngology – HNS and Molecular & Cellular Physiology, Stanford University School of Medicine, Palo Alto, California, United States of America
- * E-mail:
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Cioffi DL, Wu S, Chen H, Alexeyev M, St Croix CM, Pitt BR, Uhlig S, Stevens T. Orai1 determines calcium selectivity of an endogenous TRPC heterotetramer channel. Circ Res 2012; 110:1435-44. [PMID: 22534489 DOI: 10.1161/circresaha.112.269506] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Canonical transient receptor potential 4 (TRPC4) contributes to the molecular composition of a channel encoding for a calcium selective store-operated current, I(SOC), whereas Orai1 critically comprises a channel encoding for the highly selective calcium release activated calcium current, I(CRAC). However, Orai1 may interact with TRPC proteins and influence their activation and permeation characteristics. Endothelium expresses both TRPC4 and Orai1, and it remains unclear as to whether Orai1 interacts with TRPC4 and contributes to calcium permeation through the TPRC4 channel. OBJECTIVE We tested the hypothesis that Orai1 interacts with TRPC4 and contributes to the channel's selective calcium permeation important for endothelial barrier function. METHODS AND RESULTS A novel method to purify the endogenous TRPC4 channel and probe for functional interactions was developed, using TRPC4 binding to protein 4.1 as bait. Isolated channel complexes were conjugated to anti-TRPC protein antibodies labeled with cy3-cy5 pairs. Förster Resonance Energy Transfer among labeled subunits revealed the endogenous protein alignment. One TRPC1 and at least 2 TRPC4 subunits constituted the endogenous channel (TRPC1/4). Orai1 interacted with TRPC4. Conditional Orai1 knockdown reduced the probability for TRPC1/4 channel activation and converted it from a calcium-selective to a nonselective channel, an effect that was rescued on Orai1 reexpression. Loss of Orai1 improved endothelial cell barrier function. CONCLUSION Orai1 interacts with TRPC4 in the endogenous channel complex, where it controls TRPC1/4 activation and channel permeation characteristics, including calcium selectivity, important for control of endothelial cell barrier function.
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Affiliation(s)
- Donna L Cioffi
- Department of Biochemistry and Molecular Biology, University of South Alabama College of Medicine, Mobile, AL 36688, USA. dlcioffi@ usouthal.edu
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Lehen'kyi V, Raphaël M, Prevarskaya N. The role of the TRPV6 channel in cancer. J Physiol 2012; 590:1369-76. [PMID: 22331416 DOI: 10.1113/jphysiol.2011.225862] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Abstract The TRPV6 channel belongs to the superfamily of transient receptor potential (TRP) channels, subfamily vanilloid, member 6. Its expression in health is mainly confined to epithelial tissue of different organs such as digestive tract, kidney, testis, ovaries and skin. Due to its high calcium selectivity over other TRP channels, this channel was shown to participate in close regulation of calcium homeostasis in the body. In cancer a number of pieces of evidence demonstrate its upregulation and correlation with the advanced stages in prostate, colon, breast, thyroid, and ovarian carcinomas. Little is known about its role in initiation or progression for most of cancers, though in prostate cancer its oncogenic potential in vitro has been suggested. The most probable mechanisms involve calcium signalling in the control of processes such as proliferation and apoptosis resistance, though in some cases first evidence was reported as to its likely protective role in some cancers such as colon cancer. Further studies are needed to confirm whether this channel does really have an oncogenic potential or is just the last hope for transformed cells/tissues to stop cancer.
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Affiliation(s)
- V'yacheslav Lehen'kyi
- Inserm, U-1003, Equipe labellisée par la Ligue Nationale contre le cancer, Villeneuve d'Ascq, France
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44
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Little R, Muimo R, Robson L, Harris K, Grabowski PS. The transient receptor potential ion channel TRPV6 is expressed at low levels in osteoblasts and has little role in osteoblast calcium uptake. PLoS One 2011; 6:e28166. [PMID: 22163264 PMCID: PMC3226639 DOI: 10.1371/journal.pone.0028166] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 11/02/2011] [Indexed: 11/26/2022] Open
Abstract
Background TRPV6 ion channels are key mediators of regulated transepithelial absorption of Ca2+ within the small intestine. Trpv6-/- mice were reported to have lower bone density than wild-type littermates and significant disturbances in calcium homeostasis that suggested a role for TRPV6 in osteoblasts during bone formation and mineralization. TRPV6 and molecules related to transepithelial Ca2+ transport have been reported to be expressed at high levels in human and mouse osteoblasts. Results Transmembrane ion currents in whole cell patch clamped SaOS-2 osteoblasts did not show sensitivity to ruthenium red, an inhibitor of TRPV5/6 ion channels, and 45Ca uptake was not significantly affected by ruthenium red in either SaOS-2 (P = 0.77) or TE-85 (P = 0.69) osteoblastic cells. In contrast, ion currents and 45Ca uptake were both significantly affected in a human bronchial epithelial cell line known to express TRPV6. TRPV6 was expressed at lower levels in osteoblastic cells than has been reported in some literature. In SaOS-2 TRPV6 mRNA was below the assay detection limit; in TE-85 TRPV6 mRNA was detected at 6.90±1.9 × 10−5 relative to B2M. In contrast, TRPV6 was detected at 7.7±3.0 × 10−2 and 2.38±0.28 × 10−4 the level of B2M in human carcinoma-derived cell lines LNCaP and CaCO-2 respectively. In murine primary calvarial osteoblasts TRPV6 was detected at 3.80±0.24 × 10−5 relative to GAPDH, in contrast with 4.3±1.5 × 10−2 relative to GAPDH in murine duodenum. By immunohistochemistry, TRPV6 was expressed mainly in myleocytic cells of the murine bone marrow and was observed only at low levels in murine osteoblasts, osteocytes or growth plate cartilage. Conclusions TRPV6 is expressed only at low levels in osteoblasts and plays little functional role in osteoblastic calcium uptake.
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Affiliation(s)
- Robert Little
- Department of Human Metabolism, The Mellanby Centre for Bone Research, The University of Sheffield, Sheffield, United Kingdom
| | - Richmond Muimo
- Department of Infection and Immunity, The University of Sheffield, Sheffield, United Kingdom
| | - Louise Robson
- Department of Biomedical Science, The University of Sheffield, Sheffield, United Kingdom
| | - Kate Harris
- Department of Biomedical Science, The University of Sheffield, Sheffield, United Kingdom
| | - Peter S. Grabowski
- Department of Human Metabolism, The Mellanby Centre for Bone Research, The University of Sheffield, Sheffield, United Kingdom
- * E-mail:
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Expression patterns of intestinal calcium transport factors and ex-vivo absorption of calcium in horses. BMC Vet Res 2011; 7:65. [PMID: 22017756 PMCID: PMC3221622 DOI: 10.1186/1746-6148-7-65] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 10/22/2011] [Indexed: 11/12/2022] Open
Abstract
Background In many species, the small intestine is the major site of calcium (Ca2+) absorption. The horse differs considerably from most other species with regard to the physiology of its Ca2+ metabolism and digestion. Thus, this study was performed to get more information about the transcellular Ca2+ absorption in the horse. Two mechanisms of intestinal Ca2+ absorption are described: the passive paracellular pathway and the active, vitamin D-dependent transcellular pathway. The latter involves the following elements: vitamin D receptors (VDR), transient receptor potential vanilloid channel members 5 and 6 (TRPV5/6), calbindin-D9k (CB), the Na/Ca exchanger (NCX1) and the plasma membrane Ca-ATPase (PMCA). The aim of the present study was to investigate the protein and mRNA expression patterns of VDR, CB and TRPV6 and the ex-vivo Ca2+ absorption in horses, assessed by qualitative and quantitative RT-PCR, western blot, immunohistochemistry and the Ussing chamber technique. Results Highest CB and TRPV6 mRNA levels were detected in the duodenum as compared to the middle parts of the jejunum and ileum and several sites of the large intestine. VDR mRNA levels did not change significantly throughout the intestine. TRPV5 mRNA was not detectable in the horse intestine. The highest VDR and CB protein levels were measured in the duodenum. Ussing chamber studies revealed ex-vivo Ca2+ absorption only in the duodenum, but not in cecum and specific sites of the colon. Conclusion The present findings suggest that TRPV6, CB and VDR may be involved in active intestinal Ca2+ absorption in horses, as described for other mammals. TRPV5 may not play a major role in this process. Furthermore, the expression patterns of these Ca2+ transport elements and the results of the Ussing chamber procedure indicate that a significant part of active intestinal Ca2+ absorption occurs in the duodenum in this species.
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Zakharian E, Cao C, Rohacs T. Intracellular ATP supports TRPV6 activity via lipid kinases and the generation of PtdIns(4,5) P₂. FASEB J 2011; 25:3915-28. [PMID: 21810903 DOI: 10.1096/fj.11-184630] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Transient receptor potential vanilloid 6 (TRPV6) channels play an important role in Ca(2+) absorption in the intestines. Both phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)] and cytoplasmic ATP have been proposed to be important for maintaining TRPV6 activity. To evaluate whether PtdIns(4,5)P(2) and ATP affect channel activity directly or indirectly, we have used a dual approach, examining channel activity in excised patches and planar lipid bilayers. In excised inside-out patch-clamp measurements, ATP reactivated the human TRPV6 channels after current rundown only in the presence of Mg(2+). The effect of MgATP was inhibited by 3 structurally different compounds that inhibit type III phosphatidylinositol 4-kinases (PI4Ks). PtdIns(4,5)P(2) also activated TRPV6 in excised patches, while its precursor PtdIns(4)P had only minimal effect. These data demonstrate that MgATP provides substrate for lipid kinases, allowing the resynthesis of PtdIns(4,5)P(2). To determine whether PtdIns(4,5)P(2) is a direct activator of TRPV6, we purified and reconstituted the channel protein in planar lipid bilayers. The reconstituted channel showed high activity in the presence of PtdIns(4,5)P(2), while PtdIns(4)P induced only minimal activity. Our data establish PtdIns(4,5)P(2) as a direct activator of TRPV6 and demonstrate that intracellular ATP regulates the channel indirectly as a substrate for type III PI4Ks.
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Affiliation(s)
- Eleonora Zakharian
- University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey 07103, USA
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47
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Hwang I, Jung EM, Yang H, Choi KC, Jeung EB. Tissue-specific expression of the calcium transporter genes TRPV5, TRPV6, NCX1, and PMCA1b in the duodenum, kidney and heart of Equus caballus. J Vet Med Sci 2011; 73:1437-44. [PMID: 21737966 DOI: 10.1292/jvms.11-0141] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Calcium transporter genes, such as transient receptor potential cation channel subfamily V members 5/6 (TRPV5/6), Na(+)/Ca(2+) exchanger 1 (NCX1), and plasma membrane calcium-transporting ATPase 1b (PMCA1b), are essential for maintaining homeostasis and metabolizing Ca(2+) ions. The TRPV5 and TRPV6 proteins play an important role in Ca(2+ )absorption, and NCX1 and PMCA1b are both critical for intracellular calcium homeostasis. In this study, the tissue-specific mRNA and protein expression of these calcium transporter genes in the duodenum, kidney and heart of the horse (Equus caballus) was examined using reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis. The tissue localization of these calcium transporters was also investigated using immunohistochemistry. The results showed that TRPV5 mRNA was highly expressed in the kidney but was scarce in the duodenum and heart. TRPV6 mRNA levels were similar in all the tissues. NCX1 and PMCA1b were both highly expressed in the heart, but no difference in NCX1 and PMCA1b mRNA expressions was observed in the duodenum and kidney. The aspect of protein expression was similar with mRNA expression data. Localization of calcium transporter genes were detected enterocytes in duodenum, the distal convoluted tubules in the kidney, and within the cardiac muscle cells of the heart. Based on these results, calcium transport genes appear to be expressed in horse tissues at levels similar to those observed in other vertebrates.
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Affiliation(s)
- Inho Hwang
- Laboratory of Veterinary Biochemistry and Molecular Biology, College of Veterinary Medicine, Chungbuk National University,Cheongju, Chungbuk 361–763, Republic of Korea
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Vanoevelen J, Janssens A, Huitema LFA, Hammond CL, Metz JR, Flik G, Voets T, Schulte-Merker S. Trpv5/6 is vital for epithelial calcium uptake and bone formation. FASEB J 2011; 25:3197-207. [PMID: 21670068 DOI: 10.1096/fj.11-183145] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Calcium is an essential ion serving a multitude of physiological roles. Aside from its role as a second messenger, it is an essential component of the vertebrate bone matrix. Efficient uptake and storage of calcium are therefore indispensable for all vertebrates. Transient receptor potential family, vanilloid type (TRPV)5 and TRPV6 channels are known players in transcellular calcium uptake, but the exact contribution of this pathway is unclear. We used forward genetic screening in zebrafish (Danio rerio) to identify genes essential in bone formation and identified a lethal zebrafish mutant (matt-und-schlapp) with severe defects in bone formation, including lack of ossification of the vertebral column and craniofacial structures. Mutant embryos show a 68% reduction in calcium content, and systemic calcium homeostasis is disturbed when compared with siblings. The phenotype can be partially rescued by increasing ambient calcium levels to 25 mM. We identified the mutation as a loss-of-function mutation in the single orthologue of TRPV5 and 6, trpv5/6. Expression in HEK293 cells showed that Trpv5/6 is a calcium-selective channel capable of inward calcium transport at physiological concentrations whereas the mutant channel is not. Taken together, this study provides both genetic and functional evidence that transcellular epithelial calcium uptake is vital to sustain life and enable bone formation.
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Affiliation(s)
- Jo Vanoevelen
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences and University Medical Centre, Utrecht, The Netherlands.
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Spehr J, Gelis L, Osterloh M, Oberland S, Hatt H, Spehr M, Neuhaus EM. G protein-coupled receptor signaling via Src kinase induces endogenous human transient receptor potential vanilloid type 6 (TRPV6) channel activation. J Biol Chem 2011; 286:13184-92. [PMID: 21349844 DOI: 10.1074/jbc.m110.183525] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ca(2+) homeostasis plays a critical role in a variety of cellular processes. We showed previously that stimulation of the prostate-specific G protein-coupled receptor (PSGR) enhances cytosolic Ca(2+) and inhibits proliferation of prostate cells. Here, we analyzed the signaling mechanisms underlying the PSGR-mediated Ca(2+) increase. Using complementary molecular, biochemical, electrophysiological, and live-cell imaging techniques, we found that endogenous Ca(2+)-selective transient receptor potential vanilloid type 6 (TRPV6) channels are critically involved in the PSGR-induced Ca(2+) signal. Biophysical characterization of the current activated by PSGR stimulation revealed characteristic properties of TRPV6. The molecular identity of the involved channel was confirmed using RNA interference targeting TrpV6. TRPV6-mediated Ca(2+) influx depended on Src kinase activity. Src kinase activation occurred independently of G protein activation, presumably by direct interaction with PSGR. Taken together, we report that endogenous TRPV6 channels are activated downstream of a G protein-coupled receptor and present the first physiological characterization of these channels in situ.
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Affiliation(s)
- Jennifer Spehr
- Department of Chemosensation, RTWH Aachen University, 52074 Aachen, Germany.
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Wu LJ, Sweet TB, Clapham DE. International Union of Basic and Clinical Pharmacology. LXXVI. Current progress in the mammalian TRP ion channel family. Pharmacol Rev 2010; 62:381-404. [PMID: 20716668 DOI: 10.1124/pr.110.002725] [Citation(s) in RCA: 426] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Transient receptor potential (TRP) channels are a large family of ion channel proteins, surpassed in number in mammals only by voltage-gated potassium channels. TRP channels are activated and regulated through strikingly diverse mechanisms, making them suitable candidates for cellular sensors. They respond to environmental stimuli such as temperature, pH, osmolarity, pheromones, taste, and plant compounds, and intracellular stimuli such as Ca(2+) and phosphatidylinositol signal transduction pathways. However, it is still largely unknown how TRP channels are activated in vivo. Despite the uncertainties, emerging evidence using TRP channel knockout mice indicates that these channels have broad function in physiology. Here we review the recent progress on the physiology, pharmacology and pathophysiological function of mammalian TRP channels.
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Affiliation(s)
- Long-Jun Wu
- Howard Hughes Medical Institute, Department of Cardiology, Children's Hospital Boston, 320 Longwood Avenue, Boston, MA 02115, USA
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