1
|
Sciarroni E, Montanelli L, Di Cosmo C, Bagattini B, Comi S, Pignata L, Brancatella A, De Marco G, Ferrarini E, Nencetti C, Sessa MR, Latrofa F, Santini F, Tonacchera M, Agretti P. Late-onset dyshormonogenic goitrous hypothyroidism due to a homozygous mutation of the SLC26A7 gene: a case report. Ital J Pediatr 2024; 50:106. [PMID: 38812002 PMCID: PMC11137895 DOI: 10.1186/s13052-024-01672-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 05/06/2024] [Indexed: 05/31/2024] Open
Abstract
BACKGROUND In this study, we used targeted next-generation sequencing (NGS) to investigate the genetic basis of congenital hypothyroidism (CH) in a 19-year-old Tunisian man who presented with severe hypothyroidism and goiter. CASE PRESENTATION The propositus reported the appearance of goiter when he was 18. Importantly, he did not show signs of mental retardation, and his growth was proportionate. A partial organification defect was detected through the perchlorate-induced iodide discharge test. NGS identified a novel homozygous mutation in exon 18 of the SLC26A7 gene (P628Qfs*11), which encodes for a new iodide transporter. This variant is predicted to result in a truncated protein. Notably, the patient's euthyroid brother was heterozygous for the same mutation. No renal acid-base abnormalities were found and the administration of 1 mg of iodine failed to correct hypothyroidism. CONCLUSIONS We described the first case of goitrous CH due to a homozygous mutation of the SLC26A7 gene diagnosed during late adolescence.
Collapse
Affiliation(s)
- Elisabetta Sciarroni
- Department of Clinical and Experimental Medicine, Endocrine Unit, Research Center of Excellence AmbiSEN, University of Pisa, 56124, Pisa, Italy.
| | - Lucia Montanelli
- Department of Clinical and Experimental Medicine, Endocrine Unit, Research Center of Excellence AmbiSEN, University of Pisa, 56124, Pisa, Italy
| | - Caterina Di Cosmo
- Department of Clinical and Experimental Medicine, Endocrine Unit, Research Center of Excellence AmbiSEN, University of Pisa, 56124, Pisa, Italy
| | - Brunella Bagattini
- Department of Clinical and Experimental Medicine, Endocrine Unit, Research Center of Excellence AmbiSEN, University of Pisa, 56124, Pisa, Italy
| | - Simone Comi
- Department of Clinical and Experimental Medicine, Endocrine Unit, Research Center of Excellence AmbiSEN, University of Pisa, 56124, Pisa, Italy
| | - Luisa Pignata
- Department of Clinical and Experimental Medicine, Endocrine Unit, Research Center of Excellence AmbiSEN, University of Pisa, 56124, Pisa, Italy
| | - Alessandro Brancatella
- Department of Clinical and Experimental Medicine, Endocrine Unit, Research Center of Excellence AmbiSEN, University of Pisa, 56124, Pisa, Italy
| | - Giuseppina De Marco
- Department of Clinical and Experimental Medicine, Endocrine Unit, Research Center of Excellence AmbiSEN, University of Pisa, 56124, Pisa, Italy
| | - Eleonora Ferrarini
- Department of Clinical and Experimental Medicine, Endocrine Unit, Research Center of Excellence AmbiSEN, University of Pisa, 56124, Pisa, Italy
| | - Chiara Nencetti
- Laboratory of Chemistry and Endocrinology, University Hospital of Pisa, 56124, Pisa, Italy
| | - Maria Rita Sessa
- Laboratory of Chemistry and Endocrinology, University Hospital of Pisa, 56124, Pisa, Italy
| | - Francesco Latrofa
- Department of Clinical and Experimental Medicine, Endocrine Unit, Research Center of Excellence AmbiSEN, University of Pisa, 56124, Pisa, Italy
| | - Ferruccio Santini
- Department of Clinical and Experimental Medicine, Endocrine Unit, Research Center of Excellence AmbiSEN, University of Pisa, 56124, Pisa, Italy
| | - Massimo Tonacchera
- Department of Clinical and Experimental Medicine, Endocrine Unit, Research Center of Excellence AmbiSEN, University of Pisa, 56124, Pisa, Italy
| | - Patrizia Agretti
- Laboratory of Chemistry and Endocrinology, University Hospital of Pisa, 56124, Pisa, Italy
| |
Collapse
|
2
|
Lee D, Hong JH. Chloride/Multiple Anion Exchanger SLC26A Family: Systemic Roles of SLC26A4 in Various Organs. Int J Mol Sci 2024; 25:4190. [PMID: 38673775 PMCID: PMC11050216 DOI: 10.3390/ijms25084190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 03/31/2024] [Accepted: 04/08/2024] [Indexed: 04/28/2024] Open
Abstract
Solute carrier family 26 member 4 (SLC26A4) is a member of the SLC26A transporter family and is expressed in various tissues, including the airway epithelium, kidney, thyroid, and tumors. It transports various ions, including bicarbonate, chloride, iodine, and oxalate. As a multiple-ion transporter, SLC26A4 is involved in the maintenance of hearing function, renal function, blood pressure, and hormone and pH regulation. In this review, we have summarized the various functions of SLC26A4 in multiple tissues and organs. Moreover, the relationships between SLC26A4 and other channels, such as cystic fibrosis transmembrane conductance regulator, epithelial sodium channel, and sodium chloride cotransporter, are highlighted. Although the modulation of SLC26A4 is critical for recovery from malfunctions of various organs, development of specific inducers or agonists of SLC26A4 remains challenging. This review contributes to providing a better understanding of the role of SLC26A4 and development of therapeutic approaches for the SLC26A4-associated hearing loss and SLC26A4-related dysfunction of various organs.
Collapse
Affiliation(s)
| | - Jeong Hee Hong
- Department of Health Sciences and Technology, GAIHST (Gachon Advanced Institute for Health Sciences and Technology), Lee Gil Ya Cancer and Diabetes Institute, Gachon University, 155 Getbeolro, Yeonsu-gu, Incheon 21999, Republic of Korea;
| |
Collapse
|
3
|
Li D, Wan X, Yun Y, Li Y, Duan W. Genes Selectively Expressed in Rat Organs. Curr Genomics 2024; 25:261-297. [PMID: 39156728 PMCID: PMC11327808 DOI: 10.2174/0113892029273121240401060228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 11/24/2023] [Accepted: 12/05/2023] [Indexed: 08/20/2024] Open
Abstract
Background Understanding organic functions at a molecular level is important for scientists to unveil the disease mechanism and to develop diagnostic or therapeutic methods. Aims The present study tried to find genes selectively expressed in 11 rat organs, including the adrenal gland, brain, colon, duodenum, heart, ileum, kidney, liver, lung, spleen, and stomach. Materials and Methods Three normal male Sprague-Dawley (SD) rats were anesthetized, their organs mentioned above were harvested, and RNA in the fresh organs was extracted. Purified RNA was reversely transcribed and sequenced using the Solexa high-throughput sequencing technique. The abundance of a gene was measured by the expected value of fragments per kilobase of transcript sequence per million base pairs sequenced (FPKM). Genes in organs with the highest expression level were sought out and compared with their median value in organs. If a gene in the highest expressed organ was significantly different (p < 0.05) from that in the medianly expressed organ, accompanied by q value < 0.05, and accounted for more than 70% of the total abundance, the gene was assumed as the selective gene in the organ. Results & Discussion The Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Ontology (GO) pathways were enriched by the highest expressed genes. Based on the criterion, 1,406 selective genes were screened out, 1,283 of which were described in the gene bank and 123 of which were waiting to be described. KEGG and GO pathways in the organs were partly confirmed by the known understandings and a good portion of the pathways needed further investigation. Conclusion The novel selective genes and organic functional pathways are useful for scientists to unveil the mechanisms of the organs at the molecular level, and the selective genes' products are candidate disease markers for organs.
Collapse
Affiliation(s)
- Dan Li
- The Department of Pharmacology, School of Basic Medicine, Kunming Medical University, Kunming, 650500, China
| | - Xulian Wan
- School of Basic Medicine, Yunnan University of Traditional Chinese Medicine, Kunming, 650500, China
| | - Yu Yun
- The Department of Pharmacology, School of Basic Medicine, Kunming Medical University, Kunming, 650500, China
| | - Yongkun Li
- School of Basic Medicine, Yunnan University of Traditional Chinese Medicine, Kunming, 650500, China
| | - Weigang Duan
- School of Basic Medicine, Yunnan University of Traditional Chinese Medicine, Kunming, 650500, China
| |
Collapse
|
4
|
Bourgeois S, Houillier P. State of knowledge on ammonia handling by the kidney. Pflugers Arch 2024; 476:517-531. [PMID: 38448728 PMCID: PMC11006756 DOI: 10.1007/s00424-024-02940-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 02/28/2024] [Accepted: 03/01/2024] [Indexed: 03/08/2024]
Abstract
The disposal of ammonia, the main proton buffer in the urine, is important for acid-base homeostasis. Renal ammonia excretion is the predominant contributor to renal net acid excretion, both under basal condition and in response to acidosis. New insights into the mechanisms of renal ammonia production and transport have been gained in the past decades. Ammonia is the only urinary solute known to be produced in the kidney and selectively transported through the different parts of the nephron. Both molecular forms of total ammonia, NH3 and NH4+, are transported by specific proteins. Proximal tubular ammoniagenesis and the activity of these transport processes determine the eventual fate of total ammonia produced and excreted by the kidney. In this review, we summarized the state of the art of ammonia handling by the kidney and highlighted the newest processes described in the last decade.
Collapse
Affiliation(s)
- Soline Bourgeois
- Institut of Physiology, University of Zurich, Zurich, Switzerland.
| | - Pascal Houillier
- Centre de Recherche Des Cordeliers, INSERM, Sorbonne Université, Université Paris Cité, Paris, France
- Centre National de La Recherche Scientifique (CNRS), EMR 8228, Paris, France
| |
Collapse
|
5
|
Niciura SCM, Cardoso TF, Ibelli AMG, Okino CH, Andrade BG, Benavides MV, Chagas ACDS, Esteves SN, Minho AP, Regitano LCDA, Gondro C. Multi-omics data elucidate parasite-host-microbiota interactions and resistance to Haemonchus contortus in sheep. Parasit Vectors 2024; 17:102. [PMID: 38429820 PMCID: PMC10908167 DOI: 10.1186/s13071-024-06205-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Accepted: 02/18/2024] [Indexed: 03/03/2024] Open
Abstract
BACKGROUND The integration of molecular data from hosts, parasites, and microbiota can enhance our understanding of the complex biological interactions underlying the resistance of hosts to parasites. Haemonchus contortus, the predominant sheep gastrointestinal parasite species in the tropics, causes significant production and economic losses, which are further compounded by the diminishing efficiency of chemical control owing to anthelmintic resistance. Knowledge of how the host responds to infection and how the parasite, in combination with microbiota, modulates host immunity can guide selection decisions to breed animals with improved parasite resistance. This understanding will help refine management practices and advance the development of new therapeutics for long-term helminth control. METHODS Eggs per gram (EPG) of feces were obtained from Morada Nova sheep subjected to two artificial infections with H. contortus and used as a proxy to select animals with high resistance or susceptibility for transcriptome sequencing (RNA-seq) of the abomasum and 50 K single-nucleotide genotyping. Additionally, RNA-seq data for H. contortus were generated, and amplicon sequence variants (ASV) were obtained using polymerase chain reaction amplification and sequencing of bacterial and archaeal 16S ribosomal RNA genes from sheep feces and rumen content. RESULTS The heritability estimate for EPG was 0.12. GAST, GNLY, IL13, MGRN1, FGF14, and RORC genes and transcripts were differentially expressed between resistant and susceptible animals. A genome-wide association study identified regions on chromosomes 2 and 11 that harbor candidate genes for resistance, immune response, body weight, and adaptation. Trans-expression quantitative trait loci were found between significant variants and differentially expressed transcripts. Functional co-expression modules based on sheep genes and ASVs correlated with resistance to H. contortus, showing enrichment in pathways of response to bacteria, immune and inflammatory responses, and hub features of the Christensenellaceae, Bacteroides, and Methanobrevibacter genera; Prevotellaceae family; and Verrucomicrobiota phylum. In H. contortus, some mitochondrial, collagen-, and cuticle-related genes were expressed only in parasites isolated from susceptible sheep. CONCLUSIONS The present study identified chromosome regions, genes, transcripts, and pathways involved in the elaborate interactions between the sheep host, its gastrointestinal microbiota, and the H. contortus parasite. These findings will assist in the development of animal selection strategies for parasite resistance and interdisciplinary approaches to control H. contortus infection in sheep.
Collapse
|
6
|
Geertsma ER, Oliver D. SLC26 Anion Transporters. Handb Exp Pharmacol 2024; 283:319-360. [PMID: 37947907 DOI: 10.1007/164_2023_698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
Solute carrier family 26 (SLC26) is a family of functionally diverse anion transporters found in all kingdoms of life. Anions transported by SLC26 proteins include chloride, bicarbonate, and sulfate, but also small organic dicarboxylates such as fumarate and oxalate. The human genome encodes ten functional homologs, several of which are causally associated with severe human diseases, highlighting their physiological importance. Here, we review novel insights into the structure and function of SLC26 proteins and summarize the physiological relevance of human members.
Collapse
Affiliation(s)
- Eric R Geertsma
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.
| | - Dominik Oliver
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, Marburg, Germany.
- Center for Mind, Brain and Behavior (CMBB), Universities of Marburg and Giessen, Marburg, Giessen, Germany.
| |
Collapse
|
7
|
Yamaguchi N, Suzuki A, Yoshida A, Tanaka T, Aoyama K, Oishi H, Hara Y, Ogi T, Amano I, Kameo S, Koibuchi N, Shibata Y, Ugawa S, Mizuno H, Saitoh S. The iodide transporter Slc26a7 impacts thyroid function more strongly than Slc26a4 in mice. Sci Rep 2022; 12:11259. [PMID: 35788623 PMCID: PMC9253019 DOI: 10.1038/s41598-022-15151-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 06/20/2022] [Indexed: 11/09/2022] Open
Abstract
SLC26A4 is a known iodide transporter, and is localized at the apical membrane of thyrocytes. Previously, we reported that SLC26A7 is also involved in iodide transport and that Slc26a7 is a novel causative gene for congenital hypothyroidism. However, its detailed role in vivo remains to be elucidated. We generated mice that were deficient in Slc26a7 and Slc26a4 to delineate differences and associations in their roles in iodide transport. Slc26a7-/- mice showed goitrous congenital hypothyroidism and mild growth failure on a normal diet. Slc26a7-/- mice with a low iodine environment showed marked growth failure. In contrast, Slc26a4-/- mice showed no growth failure and hypothyroidism in the same low iodine environment. Double-deficient mice showed more severe growth failure than Slc26a7-/- mice. RNA-seq analysis revealed that the number of differentially expressed genes (DEGs) in Slc26a7-/- mice was significantly higher than that in Slc26a4-/- mice. These indicate that SLC26A7 is more strongly involved in iodide transport and the maintenance of thyroid function than SLC26A4.
Collapse
Affiliation(s)
- Naoya Yamaguchi
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1-Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Japan
| | - Atsushi Suzuki
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1-Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Japan
| | - Aya Yoshida
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1-Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Japan
| | - Tatsushi Tanaka
- Department of Pediatrics, Toyohashi Municipal Hospital, Toyohashi, Japan
| | - Kohei Aoyama
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1-Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Japan.
| | - Hisashi Oishi
- Department of Comparative and Experimental Medicine, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Yuichiro Hara
- Department of Genetics, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan.,Department of Human Genetics and Molecular Biology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Tomoo Ogi
- Department of Genetics, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan.,Department of Human Genetics and Molecular Biology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Izuki Amano
- Department of Integrative Physiology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Satomi Kameo
- Department of Nutrition, Koshien University, Takarazuka, Japan
| | - Noriyuki Koibuchi
- Department of Integrative Physiology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Yasuhiro Shibata
- Department of Anatomy and Neuroscience, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Shinya Ugawa
- Department of Anatomy and Neuroscience, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Haruo Mizuno
- Department of Pediatrics, Fujita Health University School of Medicine, Toyoake, Japan
| | - Shinji Saitoh
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1-Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Japan
| |
Collapse
|
8
|
Whittamore JM, Hatch M. Oxalate Flux Across the Intestine: Contributions from Membrane Transporters. Compr Physiol 2021; 12:2835-2875. [PMID: 34964122 DOI: 10.1002/cphy.c210013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Epithelial oxalate transport is fundamental to the role occupied by the gastrointestinal (GI) tract in oxalate homeostasis. The absorption of dietary oxalate, together with its secretion into the intestine, and degradation by the gut microbiota, can all influence the excretion of this nonfunctional terminal metabolite in the urine. Knowledge of the transport mechanisms is relevant to understanding the pathophysiology of hyperoxaluria, a risk factor in kidney stone formation, for which the intestine also offers a potential means of treatment. The following discussion presents an expansive review of intestinal oxalate transport. We begin with an overview of the fate of oxalate, focusing on the sources, rates, and locations of absorption and secretion along the GI tract. We then consider the mechanisms and pathways of transport across the epithelial barrier, discussing the transcellular, and paracellular components. There is an emphasis on the membrane-bound anion transporters, in particular, those belonging to the large multifunctional Slc26 gene family, many of which are expressed throughout the GI tract, and we summarize what is currently known about their participation in oxalate transport. In the final section, we examine the physiological stimuli proposed to be involved in regulating some of these pathways, encompassing intestinal adaptations in response to chronic kidney disease, metabolic acid-base disorders, obesity, and following gastric bypass surgery. There is also an update on research into the probiotic, Oxalobacter formigenes, and the basis of its unique interaction with the gut epithelium. © 2021 American Physiological Society. Compr Physiol 11:1-41, 2021.
Collapse
Affiliation(s)
- Jonathan M Whittamore
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Marguerite Hatch
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida, USA
| |
Collapse
|
9
|
Calvete O, Reyes J, Valdés-Socin H, Martin P, Marazuela M, Barroso A, Escalada J, Castells A, Torres-Ruiz R, Rodríguez-Perales S, Currás-Freixes M, Benítez J. Alterations in SLC4A2, SLC26A7 and SLC26A9 Drive Acid-Base Imbalance in Gastric Neuroendocrine Tumors and Uncover a Novel Mechanism for a Co-Occurring Polyautoimmune Scenario. Cells 2021; 10:3500. [PMID: 34944008 PMCID: PMC8700745 DOI: 10.3390/cells10123500] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 12/07/2021] [Indexed: 01/01/2023] Open
Abstract
Autoimmune polyendocrine syndrome (APS) is assumed to involve an immune system malfunction and entails several autoimmune diseases co-occurring in different tissues of the same patient; however, they are orphans of its accurate diagnosis, as its genetic basis and pathogenic mechanism are not understood. Our previous studies uncovered alterations in the ATPase H+/K+ Transporting Subunit Alpha (ATP4A) proton pump that triggered an internal cell acid-base imbalance, offering an autoimmune scenario for atrophic gastritis and gastric neuroendocrine tumors with secondary autoimmune pathologies. Here, we propose the genetic exploration of APS involving gastric disease to understand the underlying pathogenic mechanism of the polyautoimmune scenario. The whole exome sequencing (WES) study of five autoimmune thyrogastric families uncovered different pathogenic variants in SLC4A2, SLC26A7 and SLC26A9, which cotransport together with ATP4A. Exploratory in vitro studies suggested that the uncovered genes were involved in a pathogenic mechanism based on the alteration of the acid-base balance. Thus, we built a custom gene panel with 12 genes based on the suggested mechanism to evaluate a new series of 69 APS patients. In total, 64 filtered putatively damaging variants in the 12 genes of the panel were found in 54.17% of the studied patients and none of the healthy controls. Our studies reveal a constellation of solute carriers that co-express in the tissues affected with different autoimmune diseases, proposing a unique genetic origin for co-occurring pathologies. These results settle a new-fangled genetics-based mechanism for polyautoimmunity that explains not only gastric disease, but also thyrogastric pathology and disease co-occurrence in APS that are different from clinical incidental findings. This opens a new window leading to the prediction and diagnosis of co-occurring autoimmune diseases and clinical management of patients.
Collapse
Affiliation(s)
- Oriol Calvete
- Human Genetics Group, Spanish National Cancer Research Center (CNIO), 28029 Madrid, Spain; (P.M.); (A.B.)
- Network of Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
- Grupo Español de Tumores Neuroendocrinos y Endocrinos (GETNE), 28054 Madrid, Spain;
| | - José Reyes
- Grupo Español de Tumores Neuroendocrinos y Endocrinos (GETNE), 28054 Madrid, Spain;
- Department of Gastroenterology, Hospital Comarcal de Inca, 07300 Inca, Spain
- Health Investigation Institute (IDISBA), 07120 Palma de Mallorca, Spain
| | - Hernán Valdés-Socin
- Department of Endocrinology, Centre Hospitalier Universitaire de Liège, 4000 Liège, Belgium;
| | - Paloma Martin
- Human Genetics Group, Spanish National Cancer Research Center (CNIO), 28029 Madrid, Spain; (P.M.); (A.B.)
- Network of Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
| | - Mónica Marazuela
- Hospital la Princesa, Instituto de Investigación Princesa, University Autónoma of Madrid, 28006 Madrid, Spain;
| | - Alicia Barroso
- Human Genetics Group, Spanish National Cancer Research Center (CNIO), 28029 Madrid, Spain; (P.M.); (A.B.)
| | - Javier Escalada
- Endocrinology and Nutrition Department, Clínica Universidad de Navarra, 31008 Pamplona, Spain;
- IdiSNA, Navarra Institute for Health Research, 31008 Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, 28009 Madrid, Spain
| | - Antoni Castells
- Hospital Clinic of Barcelona, IDIBAPS, CIBEREHD, University of Barcelona, 08036 Barcelona, Spain;
| | - Raúl Torres-Ruiz
- Molecular Cytogenetics and Genome Editing Unit, Spanish National Cancer Research Center (CNIO), 28029 Madrid, Spain; (R.T.-R.); (S.R.-P.)
| | - Sandra Rodríguez-Perales
- Molecular Cytogenetics and Genome Editing Unit, Spanish National Cancer Research Center (CNIO), 28029 Madrid, Spain; (R.T.-R.); (S.R.-P.)
| | - María Currás-Freixes
- Endocrinology and Nutrition Department, Clínica Universidad de Navarra, 28027 Madrid, Spain;
| | - Javier Benítez
- Human Genetics Group, Spanish National Cancer Research Center (CNIO), 28029 Madrid, Spain; (P.M.); (A.B.)
- Network of Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
| |
Collapse
|
10
|
Watts K, Wills C, Madi A, Palles C, Maughan TS, Kaplan R, Al-Tassan NA, Kerr R, Kerr D, Gray V, West H, Houlston RS, Escott-Price V, Cheadle JP. Genome-wide association studies of toxicity to oxaliplatin and fluoropyrimidine chemotherapy with or without cetuximab in 1800 patients with advanced colorectal cancer. Int J Cancer 2021; 149:1713-1722. [PMID: 34270794 PMCID: PMC7616640 DOI: 10.1002/ijc.33739] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 05/12/2021] [Accepted: 06/08/2021] [Indexed: 01/03/2023]
Abstract
Chemotherapies administered at normal therapeutic dosages can cause significant side-effects and may result in early treatment discontinuation. Inter-individual variation in toxicity highlights the need for biomarkers to personalise treatment. We sought to identify such biomarkers by conducting 40 genome-wide association studies, together with gene and gene set analyses, for any toxicity and 10 individual toxicities in 1800 patients with advanced colorectal cancer treated with oxaliplatin and fluoropyrimidine chemotherapy ± cetuximab from the MRC COIN and COIN-B trials (385 patients received FOLFOX, 360 FOLFOX + cetuximab, 707 XELOX and 348 XELOX + cetuximab). Single nucleotide polymorphisms (SNPs), genes and gene sets that reached genome-wide or suggestive significance were validated in independent patient groups. We found that MROH5 was significantly associated with neutropenia in MAGMA gene analyses in patients treated with XELOX (P = 6.6 × 10-7 ) and was independently validated in those receiving XELOX + cetuximab; pooled P = 3.7 × 10-7 . rs13260246 at 8q21.13 was significantly associated with vomiting in patients treated with XELOX (odds ratio = 5.0, 95% confidence interval = 3.0-8.3, P = 9.8 × 10-10 ) but was not independently replicated. SNPs at 139 loci had suggestive associations for toxicities and lead SNPs at five of these were independently validated (rs6030266 with diarrhoea, rs1546161 with hand-foot syndrome, rs9601722 with neutropenia, rs13413764 with lethargy and rs4600090 with nausea; all with pooled P's < 5.0 × 10-6 ). In conclusion, the association of MROH5 with neutropenia and five other putative biomarkers warrant further investigation for their potential clinical utility. Despite our comprehensive genome-wide analyses of large, well-characterised, clinical trials, we found a lack of common variants with modest effect sizes associated with toxicities.
Collapse
Affiliation(s)
- Katie Watts
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, UK
| | - Christopher Wills
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, UK
| | - Ayman Madi
- The Clatterbridge Cancer Centre NHS Foundation Trust, Bebington, UK
| | - Claire Palles
- Institute of Cancer and Genomic Sciences, Institute of Biomedical Research, University of Birmingham, Birmingham, UK
| | - Timothy S Maughan
- CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, UK
| | - Richard Kaplan
- MRC Clinical Trials Unit, University College of London, London, UK
| | - Nada A Al-Tassan
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Rachel Kerr
- Department of Oncology, University of Oxford, Oxford, UK
| | - David Kerr
- Nuffield Department of Clinical Laboratory Sciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Victoria Gray
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, UK
| | - Hannah West
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, UK
| | - Richard S Houlston
- Division of Genetics and Epidemiology, The Institute of Cancer Research, London, UK
| | - Valentina Escott-Price
- Institute of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff, UK
| | - Jeremy P Cheadle
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, UK
| |
Collapse
|
11
|
Potter JHT, Davies KTJ, Yohe LR, Sanchez MKR, Rengifo EM, Struebig M, Warren K, Tsagkogeorga G, Lim BK, dos Reis M, Dávalos LM, Rossiter SJ. Dietary Diversification and Specialization in Neotropical Bats Facilitated by Early Molecular Evolution. Mol Biol Evol 2021; 38:3864-3883. [PMID: 34426843 PMCID: PMC8382914 DOI: 10.1093/molbev/msab028] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Dietary adaptation is a major feature of phenotypic and ecological diversification, yet the genetic basis of dietary shifts is poorly understood. Among mammals, Neotropical leaf-nosed bats (family Phyllostomidae) show unmatched diversity in diet; from a putative insectivorous ancestor, phyllostomids have radiated to specialize on diverse food sources including blood, nectar, and fruit. To assess whether dietary diversification in this group was accompanied by molecular adaptations for changing metabolic demands, we sequenced 89 transcriptomes across 58 species and combined these with published data to compare ∼13,000 protein coding genes across 66 species. We tested for positive selection on focal lineages, including those inferred to have undergone dietary shifts. Unexpectedly, we found a broad signature of positive selection in the ancestral phyllostomid branch, spanning genes implicated in the metabolism of all major macronutrients, yet few positively selected genes at the inferred switch to plantivory. Branches corresponding to blood- and nectar-based diets showed selection in loci underpinning nitrogenous waste excretion and glycolysis, respectively. Intriguingly, patterns of selection in metabolism genes were mirrored by those in loci implicated in craniofacial remodeling, a trait previously linked to phyllostomid dietary specialization. Finally, we show that the null model of the widely-used branch-site test is likely to be misspecified, with the implication that the test is too conservative and probably under-reports true cases of positive selection. Our findings point to a complex picture of adaptive radiation, in which the evolution of new dietary specializations has been facilitated by early adaptations combined with the generation of new genetic variation.
Collapse
Affiliation(s)
- Joshua H T Potter
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Kalina T J Davies
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Laurel R Yohe
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY, USA
- Department of Earth and Planetary Science, Yale University, 210 Whitney Ave, New Haven, CT, USA
| | - Miluska K R Sanchez
- Escuela Profesional de Ciencias Biológicas, Universidad Nacional de Piura, Piura, Peru
| | - Edgardo M Rengifo
- Escola Superior de Agricultura ‘Luiz de Queiroz,’ Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Piracicaba, Brazil
- Centro de Investigación Biodiversidad Sostenible (BioS), Lima, Peru
| | - Monika Struebig
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Kim Warren
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Georgia Tsagkogeorga
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Burton K Lim
- Department of Natural History, Royal Ontario Museum, Toronto, ON, Canada
| | - Mario dos Reis
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Liliana M Dávalos
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY, USA
- Consortium for Inter-Disciplinary Environmental Research, Stony Brook University, Stony Brook, NY, USA
| | - Stephen J Rossiter
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| |
Collapse
|
12
|
Wang J, Wang W, Wang H, Tuo B. Physiological and Pathological Functions of SLC26A6. Front Med (Lausanne) 2021; 7:618256. [PMID: 33553213 PMCID: PMC7859274 DOI: 10.3389/fmed.2020.618256] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 12/30/2020] [Indexed: 12/26/2022] Open
Abstract
Solute Carrier Family 26 (SLC26) is a conserved anion transporter family with 10 members in human (SLC26A1-A11, A10 being a pseudogene). All SLC26 genes except for SLC26A5 (prestin) are versatile anion exchangers with notable ability to transport a variety of anions. SLC26A6 has the most extensive exchange functions in the SLC26 family and is widely expressed in various organs and tissues of mammals. SLC26A6 has some special properties that make it play a particularly important role in ion homeostasis and acid-base balance. In the past few years, the function of SLC26A6 in the diseases has received increasing attention. SLC26A6 not only participates in the development of intestinal and pancreatic diseases but also serves a significant role in mediating nephrolithiasis, fetal skeletal dysplasia and arrhythmia. This review aims to explore the role of SLC26A6 in physiology and pathophysiology of relative mammalian organs to guide in-depth studies about related diseases of human.
Collapse
Affiliation(s)
- Juan Wang
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Wenkang Wang
- Department of Critical Care Medicine of the Third Affiliated Hospital (The First People's Hospital of Zunyi City), Zunyi Medical University, Zunyi, China
| | - Hui Wang
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| |
Collapse
|
13
|
Cao X, Soleimani M, Hughes BA. SLC26A7 constitutes the thiocyanate-selective anion conductance of the basolateral membrane of the retinal pigment epithelium. Am J Physiol Cell Physiol 2020; 319:C641-C656. [PMID: 32726161 DOI: 10.1152/ajpcell.00027.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Anion channels in the retinal pigment epithelium (RPE) play an essential role in the transport of Cl- between the outer retina and the choroidal blood to regulate the ionic composition and volume of the subretinal fluid that surrounds the photoreceptor outer segments. Recently, we reported that the anion conductance of the mouse RPE basolateral membrane is highly selective for the biologically active anion thiocyanate (SCN-), a property that does not correspond with any of the Cl- channels that have been found to be expressed in the RPE to date. The purpose of this study was to determine the extent to which SLC26A7, a SCN- permeable-anion exchanger/channel that was reported to be expressed in human RPE, contributes to the RPE basolateral anion conductance. We show by quantitative RT-PCR that Slc26a7 is highly expressed in mouse RPE compared with other members of the Slc26 gene family and Cl- channel genes known to be expressed in the RPE. By applying immunofluorescence microscopy to mouse retinal sections and isolated cells, we localized SLC26A7 to the RPE basolateral membrane. Finally, we performed whole cell and excised patch recordings from RPE cells acutely isolated from Slc26a7 knockout mice to show that the SCN- conductance and permeability of its basolateral membrane are dramatically smaller relative to wild-type mouse RPE cells. These findings establish SLC26A7 as the SCN--selective conductance of the RPE basolateral membrane and provide new insight into the physiology of an anion channel that may participate in anion transport and pH regulation by the RPE.
Collapse
Affiliation(s)
- Xu Cao
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan
| | | | - Bret A Hughes
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan.,Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| |
Collapse
|
14
|
Cebeci AN, Zou M, BinEssa HA, Alzahrani AS, Al-Rijjal RA, Al-Enezi AF, Al-Mohanna FA, Cavalier E, Meyer BF, Shi Y. Mutation of SGK3, a Novel Regulator of Renal Phosphate Transport, Causes Autosomal Dominant Hypophosphatemic Rickets. J Clin Endocrinol Metab 2020; 105:5672651. [PMID: 31821448 DOI: 10.1210/clinem/dgz260] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 12/09/2019] [Indexed: 11/19/2022]
Abstract
CONTEXT Hypophosphatemic rickets (HR) is a group of rare hereditary renal phosphate wasting disorders caused by mutations in PHEX, FGF23, DMP1, ENPP1, CLCN5, SLC9A3R1, SLC34A1, or SLC34A3. OBJECTIVE A large kindred with 5 HR patients was recruited with dominant inheritance. The study was undertaken to investigate underlying genetic defects in HR patients. DESIGN Patients and their family members were initially analyzed for PHEX and FGF23 mutations using polymerase chain reaction sequencing and copy number analysis. Exome sequencing was subsequently performed to identify novel candidate genes. RESULTS PHEX and FGF23 mutations were not detected in the patients. No copy number variation was observed in the genome using CytoScan HD array analysis. Mutations in DMP1, ENPP1, CLCN5, SLC9A3R1, SLC34A1, or SLC34A3 were also not found by exome sequencing. A novel c.979-96 T>A mutation in the SGK3 gene was found to be strictly segregated in a heterozygous pattern in patients and was not present in normal family members. The mutation is located 1 bp downstream of a highly conserved adenosine branch point, resulted in exon 13 skipping and in-frame deletion of 29 amino acids, which is part of the protein kinase domain and contains a Thr-320 phosphorylation site that is required for its activation. Protein tertiary structure modelling showed significant structural change in the protein kinase domain following the deletion. CONCLUSIONS The c.979-96 T>A splice mutation in the SGK3 gene causes exon 13 skipping and deletion of 29 amino acids in the protein kinase domain. The SGK3 mutation may cause autosomal dominant HR.
Collapse
Affiliation(s)
- Ayşe Nurcan Cebeci
- Department of Pediatric Endocrinology, Istanbul Bilim University, Istanbul, Turkey
| | - Minjing Zou
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Huda A BinEssa
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Ali S Alzahrani
- Department of Medicine King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Roua A Al-Rijjal
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Anwar F Al-Enezi
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Futwan A Al-Mohanna
- Department of Cell Biology, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Etienne Cavalier
- Department of Clinical Chemistry, University of Liège, CHU de Liège, Liège, Belgium
| | - Brian F Meyer
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Yufei Shi
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| |
Collapse
|
15
|
Abstract
Acid-base balance is critical for normal life. Acute and chronic disturbances impact cellular energy metabolism, endocrine signaling, ion channel activity, neuronal activity, and cardiovascular functions such as cardiac contractility and vascular blood flow. Maintenance and adaptation of acid-base homeostasis are mostly controlled by respiration and kidney. The kidney contributes to acid-base balance by reabsorbing filtered bicarbonate, regenerating bicarbonate through ammoniagenesis and generation of protons, and by excreting acid. This review focuses on acid-base disorders caused by renal processes, both inherited and acquired. Distinct rare inherited monogenic diseases affecting acid-base handling in the proximal tubule and collecting duct have been identified. In the proximal tubule, mutations of solute carrier 4A4 (SLC4A4) (electrogenic Na+/HCO3--cotransporter Na+/bicarbonate cotransporter e1 [NBCe1]) and other genes such as CLCN5 (Cl-/H+-antiporter), SLC2A2 (GLUT2 glucose transporter), or EHHADH (enoyl-CoA, hydratase/3-hydroxyacyl CoA dehydrogenase) causing more generalized proximal tubule dysfunction can cause proximal renal tubular acidosis resulting from bicarbonate wasting and reduced ammoniagenesis. Mutations in adenosine triphosphate ATP6V1 (B1 H+-ATPase subunit), ATPV0A4 (a4 H+-ATPase subunit), SLC4A1 (anion exchanger 1), and FOXI1 (forkhead transcription factor) cause distal renal tubular acidosis type I. Carbonic anhydrase II mutations affect several nephron segments and give rise to a mixed proximal and distal phenotype. Finally, mutations in genes affecting aldosterone synthesis, signaling, or downstream targets can lead to hyperkalemic variants of renal tubular acidosis (type IV). More common forms of renal acidosis are found in patients with advanced stages of chronic kidney disease and are owing, at least in part, to a reduced capacity for ammoniagenesis.
Collapse
Affiliation(s)
- Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland; National Center for Competence in Research Kidney, Switzerland.
| | - Pedro H Imenez Silva
- Institute of Physiology, University of Zurich, Zurich, Switzerland; National Center for Competence in Research Kidney, Switzerland
| | - Soline Bourgeois
- Institute of Physiology, University of Zurich, Zurich, Switzerland; National Center for Competence in Research Kidney, Switzerland
| |
Collapse
|
16
|
Screening and function discussion of a hereditary renal tubular acidosis family pathogenic gene. Cell Death Dis 2020; 11:159. [PMID: 32123165 PMCID: PMC7052238 DOI: 10.1038/s41419-020-2354-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/11/2020] [Accepted: 02/11/2020] [Indexed: 12/18/2022]
Abstract
Hereditary distal renal tubular acidosis (dRTA) is a rare disease of H+ excretion defect of α-intercalated cells in renal collecting duct, caused by decreased V-ATPase function due to mutations in the ATP6V1B1 or ATP6V0A4 genes. In the present study, a genetic family with 5 members of the complete dRTA phenotype were found with distal tubule H+ secretion disorder, hypokalemia, osteoporosis, and kidney stones. A variant NM_020632.2:c.1631C > T (p.Ser544Leu) in exon 16 on an ATP6V0A4 gene associated with dRTA was detected by next generation sequencing target region capture technique and verified by Sanger sequencing, which suggested that except for one of the patients who did not receive the test, the other four patients all carried the p.S544L heterozygote. In transfected HEK293T cells, cells carrying p.S544L-mut showed early weaker ATPase activity and a slower Phi recovery rate after rapid acidification. By immunofluorescence localization, it was observed that the expression level of p.S544L-mut on the cell membrane increased and the distribution was uneven. Co-immunoprecipitation showed the a4 subunit of ATP6V0A4/p.S544L-mut could not bind to the B1 subunit, which might affect the correct assembly of V-ATPase. The present study of dRTA family suggests that the p.S544L variant may be inherited in a dominant manner.
Collapse
|
17
|
Ullah AKMS, Rumley AC, Peleh V, Fernandes D, Almomani EY, Berrini M, Lashhab R, Touret N, Alexander RT, Herrmann JM, Cordat E. SLC26A7 protein is a chloride/bicarbonate exchanger and its abundance is osmolarity- and pH-dependent in renal epithelial cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183238. [PMID: 32119864 DOI: 10.1016/j.bbamem.2020.183238] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 02/19/2020] [Accepted: 02/24/2020] [Indexed: 12/23/2022]
Abstract
Acid-secreting intercalated cells of the collecting duct express the chloride/bicarbonate kidney anion exchanger 1 (kAE1) as well as SLC26A7, two proteins that colocalize in the basolateral membrane. The latter protein has been reported to function either as a chloride/bicarbonate exchanger or a chloride channel. Both kAE1 and SLC26A7 are detected in the renal medulla, an environment hyper-osmotic to plasma. Individuals with mutations in the SLC4A1 gene encoding kAE1 and mice lacking Slc26a7 develop distal renal tubular acidosis (dRTA). Here, we aimed to (i) confirm that SLC26A7 can function as chloride/bicarbonate exchanger in Madin-Darby canine kidney (MDCK) cells, and (ii) examine the behavior of SLC26A7 relative to kAE1 wild type or carrying the dRTA mutation R901X in iso- or hyper-osmotic conditions mimicking the renal medulla. Although we found that SLC26A7 abundance increases in hyper-osmotic growth medium, it is reduced in low pH growth conditions mimicking acidosis when expressed at high levels in MDCK cells. In these cells, SLC26A7 exchange activity was independent from extracellular osmolarity. When SLC26A7 protein was co-expressed with kAE1 WT or the R901X dRTA mutant, the cellular chloride/bicarbonate exchange rate was not additive compared to when proteins are expressed individually, possibly reflecting a decreased overall protein expression. Furthermore, the cellular chloride/bicarbonate exchange rate was osmolarity-independent. Together, these results show that (i) in MDCK cells, SLC26A7 is a chloride/bicarbonate exchanger whose abundance is up-regulated by high osmolarity growth medium and (ii) acidic extracellular pH decreases the abundance of SLC26A7 protein.
Collapse
Affiliation(s)
| | - A Carly Rumley
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
| | - Valentina Peleh
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Daphne Fernandes
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
| | - Ensaf Y Almomani
- Faculty of Pharmacy, Al-Zaytoonah University of Jordan, Amman, Jordan
| | - Mattia Berrini
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
| | - Rawad Lashhab
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
| | - Nicolas Touret
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
| | | | - Emmanuelle Cordat
- Department of Physiology, University of Alberta, Edmonton, AB, Canada.
| |
Collapse
|
18
|
Touré A. Importance of SLC26 Transmembrane Anion Exchangers in Sperm Post-testicular Maturation and Fertilization Potential. Front Cell Dev Biol 2019; 7:230. [PMID: 31681763 PMCID: PMC6813192 DOI: 10.3389/fcell.2019.00230] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 09/26/2019] [Indexed: 12/17/2022] Open
Abstract
In mammals, sperm cells produced within the testis are structurally differentiated but remain immotile and are unable to fertilize the oocyte unless they undergo a series of maturation events during their transit in the male and female genital tracts. This post-testicular functional maturation is known to rely on the micro-environment of both male and female genital tracts, and is tightly controlled by the pH of their luminal milieus. In particular, within the epididymis, the establishment of a low bicarbonate (HCO3–) concentration contributes to luminal acidification, which is necessary for sperm maturation and subsequent storage in a quiescent state. Following ejaculation, sperm is exposed to the basic pH of the female genital tract and bicarbonate (HCO3–), calcium (Ca2+), and chloride (Cl–) influxes induce biochemical and electrophysiological changes to the sperm cells (cytoplasmic alkalinization, increased cAMP concentration, and protein phosphorylation cascades), which are indispensable for the acquisition of fertilization potential, a process called capacitation. Solute carrier 26 (SLC26) members are conserved membranous proteins that mediate the transport of various anions across the plasma membrane of epithelial cells and constitute important regulators of pH and HCO3– concentration. Most SLC26 members were shown to physically interact and cooperate with the cystic fibrosis transmembrane conductance regulator channel (CFTR) in various epithelia, mainly by stimulating its Cl– channel activity. Among SLC26 members, the function of SLC26A3, A6, and A8 were particularly investigated in the male genital tract and the sperm cells. In this review, we will focus on SLC26s contributions to ionic- and pH-dependent processes during sperm post-testicular maturation. We will specify the current knowledge regarding their functions, based on data from the literature generated by means of in vitro and in vivo studies in knock-out mouse models together with genetic studies of infertile patients. We will also discuss the limits of those studies, the current research gaps and identify some key points for potential developments in this field.
Collapse
Affiliation(s)
- Aminata Touré
- INSERM U1016, Centre National de la Recherche Scientifique, UMR 8104, Institut Cochin, Université de Paris, Paris, France
| |
Collapse
|
19
|
Distal renal tubular acidosis: genetic causes and management. World J Pediatr 2019; 15:422-431. [PMID: 31079338 DOI: 10.1007/s12519-019-00260-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 04/12/2019] [Indexed: 12/11/2022]
Abstract
BACKGROUND Distal renal tubular acidosis (dRTA) is a kidney tubulopathy that causes a state of normal anion gap metabolic acidosis due to impairment of urine acidification. This review aims to summarize the etiology, pathophysiology, clinical findings, diagnosis and therapeutic approach of dRTA, with emphasis on genetic causes of dRTA. DATA SOURCES Literature reviews and original research articles from databases, including PubMed and Google Scholar. Manual searching was performed to identify additional studies about dRTA. RESULTS dRTA is characterized as the dysfunction of the distal urinary acidification, leading to metabolic acidosis. In pediatric patients, the most frequent etiology of dRTA is the genetic alteration of genes responsible for the codification of distal tubule channels, whereas, in adult patients, dRTA is more commonly secondary to autoimmune diseases, use of medications and uropathies. Patients with dRTA exhibit failure to thrive and important laboratory alterations, which are used to define the diagnosis. The oral alkali and potassium supplementation can correct the biochemical defects, improve clinical manifestations and avoid nephrolithiasis and nephrocalcinosis. CONCLUSIONS dRTA is a multifactorial disease leading to several clinical manifestations. Clinical and laboratory alterations can be corrected by alkali replacement therapy.
Collapse
|
20
|
Seidler U, Nikolovska K. Slc26 Family of Anion Transporters in the Gastrointestinal Tract: Expression, Function, Regulation, and Role in Disease. Compr Physiol 2019; 9:839-872. [DOI: 10.1002/cphy.c180027] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
|
21
|
Teulon J, Planelles G, Sepúlveda FV, Andrini O, Lourdel S, Paulais M. Renal Chloride Channels in Relation to Sodium Chloride Transport. Compr Physiol 2018; 9:301-342. [DOI: 10.1002/cphy.c180024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
22
|
Watanabe T. Improving outcomes for patients with distal renal tubular acidosis: recent advances and challenges ahead. PEDIATRIC HEALTH MEDICINE AND THERAPEUTICS 2018; 9:181-190. [PMID: 30588151 PMCID: PMC6296208 DOI: 10.2147/phmt.s174459] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Primary distal renal tubular acidosis (dRTA) is a rare genetic disorder caused by impaired distal acidification due to a failure of type A intercalated cells (A-ICs) in the collecting tubule. dRTA is characterized by persistent hyperchloremia, a normal plasma anion gap, and the inability to maximally lower urinary pH in the presence of systemic metabolic acidosis. Common clinical features of dRTA include vomiting, failure to thrive, polyuria, hypercalciuria, hypocitraturia, nephrocalcinosis, nephrolithiasis, growth delay, and rickets. Mutations in genes encoding three distinct transport proteins in A-ICs have been identified as causes of dRTA, including the B1/ATP6V1B1 and a4/ATP6V0A4 subunits of the vacuolar-type H+-ATPase (H+-ATPase) and the chloride–bicarbonate exchanger AE1/SLC4A1. Homozygous or compound heterozygous mutations in ATP6V1B1 and ATP6V0A4 lead to autosomal recessive (AR) dRTA. dRTA caused by SLC4A1 mutations can occur with either autosomal dominant or AR transmission. Red blood cell abnormalities have been associated with AR dRTA due to SLC4A1 mutations, including hereditary spherocytosis, Southeast Asia ovalocytosis, and others. Some patients with dRTA exhibit atypical clinical features, including transient and reversible proximal tubular dysfunction and hyperammonemia. Incomplete dRTA presents with inadequate urinary acidification, but without spontaneous metabolic acidosis and recurrent urinary stones. Heterozygous mutations in the AE1 or H+-ATPase genes have recently been reported in patients with incomplete dRTA. Early and sufficient doses of alkali treatment are needed for patients with dRTA. Normalized serum bicarbonate, urinary calcium excretion, urinary low-molecular-weight protein levels, and growth rate are good markers of adherence to and/or efficacy of treatment. The prognosis of dRTA is generally good in patients with appropriate treatment. However, recent studies showed an increased frequency of chronic kidney disease (CKD) in patients with dRTA during long-term follow-up. The precise pathogenic mechanisms of CKD in patients with dRTA are unknown.
Collapse
Affiliation(s)
- Toru Watanabe
- Department of Pediatrics, Niigata City General Hospital, Niigata City 950-1197, Japan,
| |
Collapse
|
23
|
Cangul H, Liao XH, Schoenmakers E, Kero J, Barone S, Srichomkwun P, Iwayama H, Serra EG, Saglam H, Eren E, Tarim O, Nicholas AK, Zvetkova I, Anderson CA, Frankl FEK, Boelaert K, Ojaniemi M, Jääskeläinen J, Patyra K, Löf C, Williams ED, Soleimani M, Barrett T, Maher ER, Chatterjee VK, Refetoff S, Schoenmakers N. Homozygous loss-of-function mutations in SLC26A7 cause goitrous congenital hypothyroidism. JCI Insight 2018; 3:99631. [PMID: 30333321 DOI: 10.1172/jci.insight.99631] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 09/06/2018] [Indexed: 12/27/2022] Open
Abstract
Defects in genes mediating thyroid hormone biosynthesis result in dyshormonogenic congenital hypothyroidism (CH). Here, we report homozygous truncating mutations in SLC26A7 in 6 unrelated families with goitrous CH and show that goitrous hypothyroidism also occurs in Slc26a7-null mice. In both species, the gene is expressed predominantly in the thyroid gland, and loss of function is associated with impaired availability of iodine for thyroid hormone synthesis, partially corrected in mice by iodine supplementation. SLC26A7 is a member of the same transporter family as SLC26A4 (pendrin), an anion exchanger with affinity for iodide and chloride (among others), whose gene mutations cause congenital deafness and dyshormonogenic goiter. However, in contrast to pendrin, SLC26A7 does not mediate cellular iodide efflux and hearing in affected individuals is normal. We delineate a hitherto unrecognized role for SLC26A7 in thyroid hormone biosynthesis, for which the mechanism remains unclear.
Collapse
Affiliation(s)
- Hakan Cangul
- Department of Medical Genetics, Istanbul Medipol University, International School of Medicine, Istanbul, Turkey
| | - Xiao-Hui Liao
- Department of Medicine, The University of Chicago, Chicago, Illinois, USA
| | - Erik Schoenmakers
- Metabolic Research Laboratories, Wellcome Trust-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom (UK)
| | - Jukka Kero
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland.,Department of Paediatrics, Turku University Hospital, Turku, Finland
| | - Sharon Barone
- University of Cincinnati and Veterans Administration Hospital, Cincinnati, Ohio, USA
| | | | - Hideyuki Iwayama
- Department of Medicine, The University of Chicago, Chicago, Illinois, USA
| | - Eva G Serra
- Department of Human Genetics, The Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
| | - Halil Saglam
- Uludag University School of Medicine, Department of Paediatric Endocrinology, Bursa, Turkey
| | - Erdal Eren
- Uludag University School of Medicine, Department of Paediatric Endocrinology, Bursa, Turkey
| | - Omer Tarim
- Uludag University School of Medicine, Department of Paediatric Endocrinology, Bursa, Turkey
| | - Adeline K Nicholas
- Metabolic Research Laboratories, Wellcome Trust-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom (UK)
| | - Ilona Zvetkova
- Metabolic Research Laboratories, Wellcome Trust-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom (UK)
| | - Carl A Anderson
- Department of Human Genetics, The Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
| | - Fiona E Karet Frankl
- Department of Medical Genetics and Division of Renal Medicine, University of Cambridge, Cambridge, UK
| | - Kristien Boelaert
- Institute of Metabolism and Systems Research, University of Birmingham and Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Edgbaston, Birmingham, UK
| | - Marja Ojaniemi
- PEDEGO Research Center and MRC Oulu, University of Oulu, and Department of Children and Adolescents, Oulu University Hospital, Oulu, Finland
| | - Jarmo Jääskeläinen
- Department of Pediatrics, University of Eastern Finland and Kuopio University, Hospital, Kuopio, Finland
| | - Konrad Patyra
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Christoffer Löf
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - E Dillwyn Williams
- Thyroid Carcinogenesis Group, University of Cambridge, Strangeways Research Laboratory, Cambridge, UK
| | | | - Manoocher Soleimani
- University of Cincinnati and Veterans Administration Hospital, Cincinnati, Ohio, USA
| | - Timothy Barrett
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham and Department of Endocrinology, Birmingham Children's Hospital, Birmingham, UK
| | - Eamonn R Maher
- Department of Medical Genetics, University of Cambridge and NIHR Cambridge Biomedical Research Centre, Cambridge, UK
| | - V Krishna Chatterjee
- Metabolic Research Laboratories, Wellcome Trust-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom (UK)
| | - Samuel Refetoff
- Department of Medicine, The University of Chicago, Chicago, Illinois, USA.,Department of Pediatrics and the Committee on Genetics, The University of Chicago, Chicago, Illinois, USA
| | - Nadia Schoenmakers
- Metabolic Research Laboratories, Wellcome Trust-Medical Research Council Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom (UK)
| |
Collapse
|
24
|
Kurtz I. Renal Tubular Acidosis: H +/Base and Ammonia Transport Abnormalities and Clinical Syndromes. Adv Chronic Kidney Dis 2018; 25:334-350. [PMID: 30139460 PMCID: PMC6128697 DOI: 10.1053/j.ackd.2018.05.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Renal tubular acidosis (RTA) represents a group of diseases characterized by (1) a normal anion gap metabolic acidosis; (2) abnormalities in renal HCO3- absorption or new renal HCO3- generation; (3) changes in renal NH4+, Ca2+, K+, and H2O homeostasis; and (4) extrarenal manifestations that provide etiologic diagnostic clues. The focus of this review is to give a general overview of the pathogenesis of the various clinical syndromes causing RTA with a particular emphasis on type I (hypokalemic distal RTA) and type II (proximal) RTA while reviewing their pathogenesis from a physiological "bottom-up" approach. In addition, the factors involved in the generation of metabolic acidosis in both type I and II RTA are reviewed highlighting the importance of altered renal ammonia production/partitioning and new HCO3- generation. Our understanding of the underlying tubular transport and extrarenal abnormalities has significantly improved since the first recognition of RTA as a clinical entity because of significant advances in clinical acid-base chemistry, whole tubule and single-cell H+/base transport, and the molecular characterization of the various transporters and channels that are functionally affected in patients with RTA. Despite these advances, additional studies are needed to address the underlying mechanisms involved in hypokalemia, altered ammonia production/partitioning, hypercalciuria, nephrocalcinosis, cystic abnormalities, and CKD progression in these patients.
Collapse
Affiliation(s)
- Ira Kurtz
- Division of Nephrology, David Geffen School of Medicine, and Brain Research Institute, UCLA, Los Angeles, CA.
| |
Collapse
|
25
|
Zou M, Alzahrani AS, Al-Odaib A, Alqahtani MA, Babiker O, Al-Rijjal RA, BinEssa HA, Kattan WE, Al-Enezi AF, Al Qarni A, Al-Faham MSA, Baitei EY, Alsagheir A, Meyer BF, Shi Y. Molecular Analysis of Congenital Hypothyroidism in Saudi Arabia: SLC26A7 Mutation Is a Novel Defect in Thyroid Dyshormonogenesis. J Clin Endocrinol Metab 2018; 103:1889-1898. [PMID: 29546359 DOI: 10.1210/jc.2017-02202] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 03/07/2018] [Indexed: 12/21/2022]
Abstract
CONTEXT Congenital hypothyroidism (CH) is the most common neonatal endocrine disorder, affecting one in 3000 to 4000 newborns. Since the introduction of a newborn screening program in 1988, more than 300 cases have been identified. The underlying genetic defects have not been systematically studied. OBJECTIVE To identify the mutation spectrum of CH-causing genes. METHODS Fifty-five patients from 47 families were studied by next-generation exome sequencing. RESULTS Mutations were identified in 52.7% of patients (29 of 55) in the following 11 genes: TG, TPO, DUOX2, SLC26A4, SLC26A7, TSHB, TSHR, NKX2-1, PAX8, CDCA8, and HOXB3. Among 30 patients with thyroid dyshormonogenesis, biallelic TG mutations were found in 12 patients (40%), followed by biallelic mutations in TPO (6.7%), SLC26A7 (6.7%), and DUOX2 (3.3%). Monoallelic SLC26A4 mutations were found in two patients, one of them coexisting with two tandem biallelic deletions in SLC26A7. In 25 patients with thyroid dysgenesis, biallelic mutations in TSHR were found in six patients (24%). Biallelic mutations in TSHB, PAX 8, NKX2-1, or HOXB3 were found once in four different patients. A monoallelic CDCA8 mutation was found in one patient. Most mutations were novel, including three TG, two TSHR, and one each in DUOX2, TPO, SLC26A7, TSHB, NKX2-1, PAX8, CDCA8, and HOXB3. SLC26A7 and HOXB3 were novel genes associated with thyroid dyshormonogenesis and dysgenesis, respectively. CONCLUSIONS TG and TSHR mutations are the most common genetic defects in Saudi patients with CH. The prevalence of other disease-causing mutations is low, reflecting the consanguineous nature of the population. SLC26A7 mutations appear to be associated with thyroid dyshormonogenesis.
Collapse
Affiliation(s)
- Minjing Zou
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Ali S Alzahrani
- Department of Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Ali Al-Odaib
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | | | - Omer Babiker
- Department of Medicine, King Abdulaziz Hospital, National Guard Health Affairs, Al Ahsa, Saudi Arabia
| | - Roua A Al-Rijjal
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Huda A BinEssa
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Walaa E Kattan
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Anwar F Al-Enezi
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Ali Al Qarni
- Department of Pediatrics, King Abdulaziz Hospital, National Guard Health Affairs, Al Ahsa, Saudi Arabia
| | - Manar S A Al-Faham
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Essa Y Baitei
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Afaf Alsagheir
- Department of Pediatrics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Brian F Meyer
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Yufei Shi
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| |
Collapse
|
26
|
Parker MD. Mouse models of SLC4-linked disorders of HCO 3--transporter dysfunction. Am J Physiol Cell Physiol 2018; 314:C569-C588. [PMID: 29384695 DOI: 10.1152/ajpcell.00301.2017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The SLC4 family Cl-/[Formula: see text] cotransporters (NBCe1, NBCe2, NBCn1, and NBCn2) contribute to a variety of vital physiological processes including pH regulation and epithelial fluid secretion. Accordingly, their dysfunction can have devastating effects. Disorders such as epilepsy, hemolytic anemia, glaucoma, hearing loss, osteopetrosis, and renal tubular acidosis are all genetically linked to SLC4-family gene loci. This review summarizes how studies of Slc4-modified mice have enhanced our understanding of the etiology of SLC4-linked pathologies and the interpretation of genetic linkage studies. The review also surveys the novel disease signs exhibited by Slc4-modified mice which could either be considered to presage their description in humans, or to highlight interspecific differences. Finally, novel Slc4-modified mouse models are proposed, the study of which may further our understanding of the basis and treatment of SLC4-linked disorders of [Formula: see text]-transporter dysfunction.
Collapse
Affiliation(s)
- Mark D Parker
- Department of Physiology and Biophysics, The State University of New York: The University at Buffalo , Buffalo, New York.,Department of Ophthalmology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo: The State University of New York , Buffalo, New York.,State University of New York Eye Institutes, University at Buffalo: The State University of New York , Buffalo, New York
| |
Collapse
|
27
|
Abstract
Amelogenesis (tooth enamel formation) is a biomineralization process consisting primarily of two stages (secretory stage and maturation stage) with unique features. During the secretory stage, the inner epithelium of the enamel organ (i.e., the ameloblast cells) synthesizes and secretes enamel matrix proteins (EMPs) into the enamel space. The protein-rich enamel matrix forms a highly organized architecture in a pH-neutral microenvironment. As amelogenesis transitions to maturation stage, EMPs are degraded and internalized by ameloblasts through endosomal-lysosomal pathways. Enamel crystallite formation is initiated early in the secretory stage, however, during maturation stage the more rapid deposition of calcium and phosphate into the enamel space results in a rapid expansion of crystallite length and mineral volume. During maturation-stage amelogenesis, the pH value of enamel varies considerably from slightly above neutral to acidic. Extracellular acid-base balance during enamel maturation is tightly controlled by ameloblast-mediated regulatory networks, which include significant synthesis and movement of bicarbonate ions from both the enamel papillary layer cells and ameloblasts. In this review we summarize the carbonic anhydrases and the carbonate transporters/exchangers involved in pH regulation in maturation-stage amelogenesis. Proteins that have been shown to be instrumental in this process include CA2, CA6, CFTR, AE2, NBCe1, SLC26A1/SAT1, SLC26A3/DRA, SLC26A4/PDS, SLC26A6/PAT1, and SLC26A7/SUT2. In addition, we discuss the association of miRNA regulation with bicarbonate transport in tooth enamel formation.
Collapse
Affiliation(s)
- Kaifeng Yin
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, 2250 Alcazar Street, CSA103, Los Angeles, CA, 90033, USA
- Department of Orthodontics, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA
| | - Michael L Paine
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, 2250 Alcazar Street, CSA103, Los Angeles, CA, 90033, USA.
| |
Collapse
|
28
|
Pathophysiology, diagnosis and treatment of inherited distal renal tubular acidosis. J Nephrol 2017; 31:511-522. [DOI: 10.1007/s40620-017-0447-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 09/21/2017] [Indexed: 10/18/2022]
|
29
|
Yin K, Guo J, Lin W, Robertson SYT, Soleimani M, Paine ML. Deletion of Slc26a1 and Slc26a7 Delays Enamel Mineralization in Mice. Front Physiol 2017; 8:307. [PMID: 28559854 PMCID: PMC5432648 DOI: 10.3389/fphys.2017.00307] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 04/28/2017] [Indexed: 12/12/2022] Open
Abstract
Amelogenesis features two major developmental stages—secretory and maturation. During maturation stage, hydroxyapatite deposition and matrix turnover require delicate pH regulatory mechanisms mediated by multiple ion transporters. Several members of the Slc26 gene family (Slc26a1, Slc26a3, Slc26a4, Slc26a6, and Slc26a7), which exhibit bicarbonate transport activities, have been suggested by previous studies to be involved in maturation-stage amelogenesis, especially the key process of pH regulation. However, details regarding the functional role of these genes in enamel formation are yet to be clarified, as none of the separate mutant animal lines demonstrates any discernible enamel defects. Continuing with our previous investigation of Slc26a1−/− and Slc26a7−/− animal models, we generated a double-mutant animal line with the absence of both Slc26a1 and Slc26a7. We showed in the present study that the double-mutant enamel density was significantly lower in the regions that represent late maturation-, maturation- and secretory-stage enamel development in wild-type mandibular incisors. However, the “maturation” and “secretory” enamel microstructures in double-mutant animals resembled those observed in wild-type secretory and/or pre-secretory stages. Elemental composition analysis revealed a lack of mineral deposition and an accumulation of carbon and chloride in double-mutant enamel. Deletion of Slc26a1 and Slc26a7 did not affect the stage-specific morphology of the enamel organ. Finally, compensatory expression of pH regulator genes and ion transporters was detected in maturation-stage enamel organs of double-mutant animals when compared to wild-type. Combined with the findings from our previous study, these data indicate the involvement of SLC26A1and SLC26A7 as key ion transporters in the pH regulatory network during enamel maturation.
Collapse
Affiliation(s)
- Kaifeng Yin
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry of University of Southern CaliforniaLos Angeles, CA, USA.,Department of Orthodontics, Herman Ostrow School of Dentistry of University of Southern CaliforniaLos Angeles, CA, USA
| | - Jing Guo
- Department of Endodontics, Herman Ostrow School of Dentistry of University of Southern CaliforniaLos Angeles, CA, USA
| | - Wenting Lin
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry of University of Southern CaliforniaLos Angeles, CA, USA
| | - Sarah Y T Robertson
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry of University of Southern CaliforniaLos Angeles, CA, USA
| | - Manoocher Soleimani
- Department of Medicine, University of Cincinnati, Research Services, Veterans Affairs Medical CenterCincinnati, OH, USA
| | - Michael L Paine
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry of University of Southern CaliforniaLos Angeles, CA, USA
| |
Collapse
|
30
|
Duverger O, Ohara T, Bible PW, Zah A, Morasso MI. DLX3-Dependent Regulation of Ion Transporters and Carbonic Anhydrases is Crucial for Enamel Mineralization. J Bone Miner Res 2017; 32:641-653. [PMID: 27760456 PMCID: PMC11025043 DOI: 10.1002/jbmr.3022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 10/10/2016] [Accepted: 10/14/2016] [Indexed: 12/11/2022]
Abstract
Patients with tricho-dento-osseous (TDO) syndrome, an ectodermal dysplasia caused by mutations in the homeodomain transcription factor DLX3, exhibit enamel hypoplasia and hypomineralization. Here we used a conditional knockout mouse model to investigate the developmental and molecular consequences of Dlx3 deletion in the dental epithelium in vivo. Dlx3 deletion in the dental epithelium resulted in the formation of chalky hypomineralized enamel in all teeth. Interestingly, transcriptomic analysis revealed that major enamel matrix proteins and proteases known to be involved in enamel secretion and maturation were not affected significantly by Dlx3 deletion in the enamel organ. In contrast, expression of several ion transporters and carbonic anhydrases known to play an important role in enamel pH regulation during maturation was significantly affected in enamel organs lacking DLX3. Most of these affected genes showed binding of DLX3 to their proximal promoter as evidenced by chromatin immunoprecipitation sequencing (ChIP-seq) analysis on rat enamel organ. These molecular findings were consistent with altered pH staining evidenced by disruption of characteristic pH oscillations in the enamel. Taken together, these results show that DLX3 is indispensable for the regulation of ion transporters and carbonic anhydrases during the maturation stage of amelogenesis, exerting a crucial regulatory function on pH oscillations during enamel mineralization. © 2016 American Society for Bone and Mineral Research.
Collapse
Affiliation(s)
- Olivier Duverger
- Laboratory of Skin Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Takahiro Ohara
- Laboratory of Skin Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Paul W Bible
- Laboratory of Skin Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Angela Zah
- Laboratory of Skin Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Maria I Morasso
- Laboratory of Skin Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| |
Collapse
|
31
|
Langford R, Hurrion E, Dawson PA. Genetics and pathophysiology of mammalian sulfate biology. J Genet Genomics 2017; 44:7-20. [DOI: 10.1016/j.jgg.2016.08.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 08/08/2016] [Accepted: 08/11/2016] [Indexed: 12/23/2022]
|
32
|
Almomani E, Lashhab R, Alexander RT, Cordat E. The carboxyl-terminally truncated kidney anion exchanger 1 R901X dRTA mutant is unstable at the plasma membrane. Am J Physiol Cell Physiol 2016; 310:C764-72. [DOI: 10.1152/ajpcell.00305.2015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 03/04/2016] [Indexed: 12/26/2022]
Abstract
Mutations in the SLC4A1 gene coding for kidney anion exchanger 1 (kAE1) cause distal renal tubular acidosis (dRTA). We investigated the fate of the most common truncated dominant dRTA mutant kAE1 R901X. In renal epithelial cells, we found that kAE1 R901X is less abundant than kAE1 wild-type (WT) at the plasma membrane. Although kAE1 WT and kAE1 R901X have similar half-lives, the decreased abundance of kAE1 R901X at the surface is due to an increased endocytosis rate and a decreased recycling rate of endocytosed proteins. We propose that, in polarized renal epithelial cells, the apically mistargeted kAE1 R901X mutant is endocytosed faster than kAE1 WT and its recycling to the basolateral membrane is delayed. This resets the equilibrium, such that kAE1 R901X resides predominantly in an endomembrane compartment, thereby likely participating in development of dRTA disease.
Collapse
Affiliation(s)
- Ensaf Almomani
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; and
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Rawad Lashhab
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; and
| | - R. Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; and
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Emmanuelle Cordat
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; and
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| |
Collapse
|
33
|
Extracellular Cl(-) regulates human SO4 (2-)/anion exchanger SLC26A1 by altering pH sensitivity of anion transport. Pflugers Arch 2016; 468:1311-32. [PMID: 27125215 DOI: 10.1007/s00424-016-1823-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 04/03/2016] [Accepted: 04/07/2016] [Indexed: 12/16/2022]
Abstract
Genetic deficiency of the SLC26A1 anion exchanger in mice is known to be associated with hyposulfatemia and hyperoxaluria with nephrolithiasis, but many aspects of human SLC26A1 function remain to be explored. We report here the functional characterization of human SLC26A1, a 4,4'-diisothiocyanato-2,2'-stilbenedisulfonic acid (DIDS)-sensitive, electroneutral sodium-independent anion exchanger transporting sulfate, oxalate, bicarbonate, thiosulfate, and (with divergent properties) chloride. Human SLC26A1-mediated anion exchange differs from that of its rodent orthologs in its stimulation by alkaline pHo and inhibition by acidic pHo but not pHi and in its failure to transport glyoxylate. SLC26A1-mediated transport of sulfate and oxalate is highly dependent on allosteric activation by extracellular chloride or non-substrate anions. Extracellular chloride stimulates apparent V max of human SLC26A1-mediated sulfate uptake by conferring a 2-log decrease in sensitivity to inhibition by extracellular protons, without changing transporter affinity for extracellular sulfate. In contrast to SLC26A1-mediated sulfate transport, SLC26A1-associated chloride transport is activated by acid pHo, shows reduced sensitivity to DIDS, and exhibits cation dependence of its DIDS-insensitive component. Human SLC26A1 resembles SLC26 paralogs in its inhibition by phorbol ester activation of protein kinase C (PKC), which differs in its undiminished polypeptide abundance at or near the oocyte surface. Mutation of SLC26A1 residues corresponding to candidate anion binding site-associated residues in avian SLC26A5/prestin altered anion transport in patterns resembling those of prestin. However, rare SLC26A1 polymorphic variants from a patient with renal Fanconi Syndrome and from a patient with nephrolithiasis/calcinosis exhibited no loss-of-function phenotypes consistent with disease pathogenesis.
Collapse
|
34
|
Hosoya M, Fujioka M, Kobayashi R, Okano H, Ogawa K. Overlapping expression of anion exchangers in the cochlea of a non-human primate suggests functional compensation. Neurosci Res 2016; 110:1-10. [PMID: 27091614 DOI: 10.1016/j.neures.2016.04.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 03/27/2016] [Accepted: 04/05/2016] [Indexed: 11/19/2022]
Abstract
Ion homeostasis in the inner ear is essential for proper hearing. Anion exchangers are one of the transporters responsible for the maintenance of homeostasis, but their expression profile in the primate cochlea has not been fully characterized. However, species-specific overlapping expression patterns and functional compensation in other organs, such as the kidney, pancreas and small intestine, have been reported. Here, we determined the expression patterns of the anion exchangers SLC26A4, SLC26A5, SLC26A6, SLC26A7, SLC26A11, SLC4A2 and SLC4A3 in the cochlea of a non-human primate, the common marmoset (Callithrix jacchus). Although the pattern of expression of SLC26A4 and SLC26A5 was similar to that in rodents, SLC26A7, SLC4A2, SLC4A3 exhibited different distributions. Notably, five transporters, SLC26A4, SLC26A6, SLC26A11 SLC4A2 and SLC4A3, were expressed in the cells of the outer sulcus. Our results reveal a species-specific distribution pattern of anion exchangers in the cochlea, particularly in the outer sulcus cells, suggesting functional compensation among these exchangers. This "primate-specific" pattern may be related to the human-specific hearing loss phenotypes of channelopathy disorders, including the SLC26A4-related diseases Pendred syndrome/DFNB4.
Collapse
Affiliation(s)
- Makoto Hosoya
- Keio University School of Medicine, Department of Otorhinolaryngology, Head and Neck Surgery, 35 Shinanomachi, Shinjuku-ku 160-8582, Japan
| | - Masato Fujioka
- Keio University School of Medicine, Department of Otorhinolaryngology, Head and Neck Surgery, 35 Shinanomachi, Shinjuku-ku 160-8582, Japan.
| | - Reona Kobayashi
- Keio University School of Medicine, Department of Physiology, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Hideyuki Okano
- Keio University School of Medicine, Department of Physiology, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Kaoru Ogawa
- Keio University School of Medicine, Department of Otorhinolaryngology, Head and Neck Surgery, 35 Shinanomachi, Shinjuku-ku 160-8582, Japan
| |
Collapse
|
35
|
Cheng Y, El-Kattan A, Zhang Y, Ray AS, Lai Y. Involvement of Drug Transporters in Organ Toxicity: The Fundamental Basis of Drug Discovery and Development. Chem Res Toxicol 2016; 29:545-63. [DOI: 10.1021/acs.chemrestox.5b00511] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Yaofeng Cheng
- Pharmaceutical
Candidate Optimization, Bristol-Myers Squibb Company, 3551 Lawrenceville
Road, Princeton, New Jersey 08540, United States
| | - Ayman El-Kattan
- Department
of Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc., 610 Main
Street, Cambridge, Massachusetts 02139, United States
| | - Yan Zhang
- Drug
Metabolism and Biopharmaceutics, Incyte Corporation, 1801 Augustine
Cutoff, Wilmington, Delaware 19803, United States
| | - Adrian S. Ray
- Department
of Drug Metabolism, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, California 94404, United States
| | - Yurong Lai
- Pharmaceutical
Candidate Optimization, Bristol-Myers Squibb Company, 3551 Lawrenceville
Road, Princeton, New Jersey 08540, United States
| |
Collapse
|
36
|
Yin K, Lei Y, Wen X, Lacruz RS, Soleimani M, Kurtz I, Snead ML, White SN, Paine ML. SLC26A Gene Family Participate in pH Regulation during Enamel Maturation. PLoS One 2015; 10:e0144703. [PMID: 26671068 PMCID: PMC4679777 DOI: 10.1371/journal.pone.0144703] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 11/23/2015] [Indexed: 12/15/2022] Open
Abstract
The bicarbonate transport activities of Slc26a1, Slc26a6 and Slc26a7 are essential to physiological processes in multiple organs. Although mutations of Slc26a1, Slc26a6 and Slc26a7 have not been linked to any human diseases, disruption of Slc26a1, Slc26a6 or Slc26a7 expression in animals causes severe dysregulation of acid-base balance and disorder of anion homeostasis. Amelogenesis, especially the enamel formation during maturation stage, requires complex pH regulation mechanisms based on ion transport. The disruption of stage-specific ion transporters frequently results in enamel pathosis in animals. Here we present evidence that Slc26a1, Slc26a6 and Slc26a7 are highly expressed in rodent incisor ameloblasts during maturation-stage tooth development. In maturation-stage ameloblasts, Slc26a1, Slc26a6 and Slc26a7 show a similar cellular distribution as the cystic fibrosis transmembrane conductance regulator (Cftr) to the apical region of cytoplasmic membrane, and the distribution of Slc26a7 is also seen in the cytoplasmic/subapical region, presumably on the lysosomal membrane. We have also examined Slc26a1 and Slc26a7 null mice, and although no overt abnormal enamel phenotypes were observed in Slc26a1-/- or Slc26a7-/- animals, absence of Slc26a1 or Slc26a7 results in up-regulation of Cftr, Ca2, Slc4a4, Slc4a9 and Slc26a9, all of which are involved in pH homeostasis, indicating that this might be a compensatory mechanism used by ameloblasts cells in the absence of Slc26 genes. Together, our data show that Slc26a1, Slc26a6 and Slc26a7 are novel participants in the extracellular transport of bicarbonate during enamel maturation, and that their functional roles may be achieved by forming interaction units with Cftr.
Collapse
Affiliation(s)
- Kaifeng Yin
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry of University of Southern California, Los Angeles, California, United States of America
| | - Yuejuan Lei
- Department of Operative and Endodontics, The Affiliated Stomatological Hospital, Guangxi Medical University, Nanning, Guangxi, China
| | - Xin Wen
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry of University of Southern California, Los Angeles, California, United States of America
| | - Rodrigo S. Lacruz
- Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, New York, United States of America
| | - Manoocher Soleimani
- Department of Medicine, University of Cincinnati, Research Services, Veterans Affairs Medical Center, Cincinnati, Ohio, United States of America
| | - Ira Kurtz
- Division of Nephrology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, United States of America
| | - Malcolm L. Snead
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry of University of Southern California, Los Angeles, California, United States of America
| | - Shane N. White
- School of Dentistry, University of California Los Angeles, Los Angeles, California, United States of America
| | - Michael L. Paine
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry of University of Southern California, Los Angeles, California, United States of America
- * E-mail:
| |
Collapse
|
37
|
Effect of SLC26 anion transporter disease-causing mutations on the stability of the homologous STAS domain of E. coli DauA (YchM). Biochem J 2015; 473:615-26. [PMID: 26635355 DOI: 10.1042/bj20151025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 12/03/2015] [Indexed: 01/08/2023]
Abstract
The human solute carrier 26 (SLC26) family of anion transporters consists of ten members that are found in various organs in the body including the stomach, intestine, kidney, thyroid and ear where they transport anions including bicarbonate, chloride and sulfate, typically in an exchange mode. Mutations in these genes cause a plethora of diseases such as diastrophic dysplasia affecting sulfate uptake into chondrocytes (SLC26A2), congenital chloride-losing diarrhoea (SLC26A3) affecting chloride secretion in the intestine and Pendred's syndrome (SLC26A4) resulting in hearing loss. To understand how these mutations affect the structures of the SLC26 membrane proteins and their ability to function properly, 12 human disease-causing mutants from SLC26A2, SLC26A3 and SLC26A4 were introduced into the equivalent sites of the sulfate transporter anti-sigma factor antagonist (STAS) domain of a bacterial homologue SLC26 protein DauA (YchM). Biophysical analyses including size-exclusion chromatography, circular dichroism (CD), differential scanning fluorimetry (DSF) and tryptophan fluorescence revealed that most mutations caused protein instability and aggregation. The mutation A463K, equivalent to N558K in human SLC26A4, which is located within α-helix 1 of the DauA STAS domain, stabilized the protein. CD measurements showed that most disease-related mutants had a mildly reduced helix content, but were more sensitive to thermal denaturation. Fluorescence spectroscopy showed that the mutants had more open structures and were more readily denatured by urea, whereas DSF indicated more labile folds. Overall, we conclude that the disease-associated mutations destabilized the STAS domain resulting in an increased propensity to misfold and aggregate.
Collapse
|
38
|
The first whole genome and transcriptome of the cinereous vulture reveals adaptation in the gastric and immune defense systems and possible convergent evolution between the Old and New World vultures. Genome Biol 2015; 16:215. [PMID: 26486310 PMCID: PMC4618389 DOI: 10.1186/s13059-015-0780-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 09/15/2015] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND The cinereous vulture, Aegypius monachus, is the largest bird of prey and plays a key role in the ecosystem by removing carcasses, thus preventing the spread of diseases. Its feeding habits force it to cope with constant exposure to pathogens, making this species an interesting target for discovering functionally selected genetic variants. Furthermore, the presence of two independently evolved vulture groups, Old World and New World vultures, provides a natural experiment in which to investigate convergent evolution due to obligate scavenging. RESULTS We sequenced the genome of a cinereous vulture, and mapped it to the bald eagle reference genome, a close relative with a divergence time of 18 million years. By comparing the cinereous vulture to other avian genomes, we find positively selected genetic variations in this species associated with respiration, likely linked to their ability of immune defense responses and gastric acid secretion, consistent with their ability to digest carcasses. Comparisons between the Old World and New World vulture groups suggest convergent gene evolution. We assemble the cinereous vulture blood transcriptome from a second individual, and annotate genes. Finally, we infer the demographic history of the cinereous vulture which shows marked fluctuations in effective population size during the late Pleistocene. CONCLUSIONS We present the first genome and transcriptome analyses of the cinereous vulture compared to other avian genomes and transcriptomes, revealing genetic signatures of dietary and environmental adaptations accompanied by possible convergent evolution between the Old World and New World vultures.
Collapse
|
39
|
Wang YY, Li Z, Chen T, Zhao XM. Understanding the aristolochic acid toxicities in rat kidneys with regulatory networks. IET Syst Biol 2015; 9:141-6. [PMID: 26243830 PMCID: PMC8687369 DOI: 10.1049/iet-syb.2014.0057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 02/01/2015] [Accepted: 02/14/2015] [Indexed: 01/11/2023] Open
Abstract
The natural products containing aristolochic acid (AA) have been widely used for acne, gastritis and so on. Recently, it is becoming accepted that AA may be responsible for acute and chronic renal failures as the side effects of Chinese herbs. However, it is unclear what happens in the cells after the AA treatment. In this study, the authors built a gene regulatory network as well as a microRNA-gene regulatory network to investigate the molecular dynamics induced by AA from a systematic perspective. With the regulatory networks, they detected some important pathways and biological processes that were affected by AA treatment, which can help explain the nephrotoxicity and carcinogenicity of AA. They found some important regulators and genes responding to AA treatment, and these genes have been reported to be related to the kidney functions, indicating their important roles in the toxicity of AA.
Collapse
Affiliation(s)
- Yin-Ying Wang
- School of Communication and Information Engineering, Shanghai University, Shanghai 200444, People's Republic of China
| | - Zhiguang Li
- Institute of Cancer Stem Cell, Cancer Center, Dalian Medical University, 9 Lvshun Road South, Dalian, Liaoning 116044, People's Republic of China
| | - Tao Chen
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA
| | - Xing-Ming Zhao
- Department of Computer Science, School of Electronics and Information Engineering, Tongji University, Shanghai 201804, People's Republic of China.
| |
Collapse
|
40
|
van den Wildenberg MJ, Hoorn EJ, Mohebbi N, Wagner CA, Woittiez AJ, de Vries PAM, Laverman GD. Distal renal tubular acidosis with multiorgan autoimmunity: a case report. Am J Kidney Dis 2014; 65:607-10. [PMID: 25533600 DOI: 10.1053/j.ajkd.2014.09.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 09/11/2014] [Indexed: 11/11/2022]
Abstract
A 61-year-old woman with a history of pernicious anemia presented with progressive muscle weakness and dysarthria. Hypokalemic paralysis (serum potassium, 1.4 mEq/L) due to distal renal tubular acidosis (dRTA) was diagnosed. After excluding several possible causes, dRTA was considered autoimmune. However, the patient did not meet criteria for any of the autoimmune disorders classically associated with dRTA. She had very high antibody titers against parietal cells, intrinsic factor, and thyroid peroxidase (despite normal thyroid function). The patient consented to a kidney biopsy, and acid-base transporters, anion exchanger type 1 (AE1), and pendrin were undetectable by immunofluorescence. Indirect immunofluorescence detected diminished abundance of AE1- and pendrin-expressing intercalated cells in the kidney, as well as staining by the patient's serum of normal human intercalated cells and parietal cells expressing the adenosine triphosphatase hydrogen/potassium pump (H(+)/K(+)-ATPase) in normal human gastric mucosa. The dRTA likely is caused by circulating autoantibodies against intercalated cells, with possible cross-reactivity against structures containing gastric H(+)/K(+)-ATPase. This case demonstrates that in patients with dRTA without a classic autoimmune disorder, autoimmunity may still be the underlying cause. The mechanisms involved in autoantibody development and how dRTA can be caused by highly specific autoantibodies against intercalated cells have yet to be determined.
Collapse
Affiliation(s)
| | - Ewout J Hoorn
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Nilufar Mohebbi
- Division of Nephrology, University Hospital Zurich, Zürich, Switzerland; Institute of Physiology and Zürich Center for Human Intergrative Physiology, University of Zürich, Zürich, Switzerland
| | - Carsten A Wagner
- Institute of Physiology and Zürich Center for Human Intergrative Physiology, University of Zürich, Zürich, Switzerland
| | | | | | | |
Collapse
|
41
|
Moss DM, Neary M, Owen A. The role of drug transporters in the kidney: lessons from tenofovir. Front Pharmacol 2014; 5:248. [PMID: 25426075 PMCID: PMC4227492 DOI: 10.3389/fphar.2014.00248] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 10/24/2014] [Indexed: 12/15/2022] Open
Abstract
Tenofovir disoproxil fumarate, the prodrug of nucleotide reverse transcriptase inhibitor tenofovir, shows high efficacy and relatively low toxicity in HIV patients. However, long-term kidney toxicity is now acknowledged as a modest but significant risk for tenofovir-containing regimens, and continuous use of tenofovir in HIV therapy is currently under question by practitioners and researchers. Co-morbidities (hepatitis C, diabetes), low body weight, older age, concomitant administration of potentially nephrotoxic drugs, low CD4 count, and duration of therapy are all risk factors associated with tenofovir-associated tubular dysfunction. Tenofovir is predominantly eliminated via the proximal tubules of the kidney, therefore drug transporters expressed in renal proximal tubule cells are believed to influence tenofovir plasma concentration and toxicity in the kidney. We review here the current evidence that the actions, pharmacogenetics, and drug interactions of drug transporters are relevant factors for tenofovir-associated tubular dysfunction. The use of creatinine and novel biomarkers for kidney damage, and the role that drug transporters play in biomarker disposition, are discussed. The lessons learnt from investigating the role of transporters in tenofovir kidney elimination and toxicity can be utilized for future drug development and clinical management programs.
Collapse
Affiliation(s)
- Darren M Moss
- Department of Molecular and Clinical Pharmacology, University of Liverpool Liverpool, UK
| | - Megan Neary
- Department of Molecular and Clinical Pharmacology, University of Liverpool Liverpool, UK
| | - Andrew Owen
- Department of Molecular and Clinical Pharmacology, University of Liverpool Liverpool, UK
| |
Collapse
|
42
|
Brommage R, Liu J, Hansen GM, Kirkpatrick LL, Potter DG, Sands AT, Zambrowicz B, Powell DR, Vogel P. High-throughput screening of mouse gene knockouts identifies established and novel skeletal phenotypes. Bone Res 2014; 2:14034. [PMID: 26273529 PMCID: PMC4472125 DOI: 10.1038/boneres.2014.34] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 07/29/2014] [Accepted: 07/31/2014] [Indexed: 12/13/2022] Open
Abstract
Screening gene function in vivo is a powerful approach to discover novel drug targets. We present high-throughput screening (HTS) data for 3 762 distinct global gene knockout (KO) mouse lines with viable adult homozygous mice generated using either gene-trap or homologous recombination technologies. Bone mass was determined from DEXA scans of male and female mice at 14 weeks of age and by microCT analyses of bones from male mice at 16 weeks of age. Wild-type (WT) cagemates/littermates were examined for each gene KO. Lethality was observed in an additional 850 KO lines. Since primary HTS are susceptible to false positive findings, additional cohorts of mice from KO lines with intriguing HTS bone data were examined. Aging, ovariectomy, histomorphometry and bone strength studies were performed and possible non-skeletal phenotypes were explored. Together, these screens identified multiple genes affecting bone mass: 23 previously reported genes (Calcr, Cebpb, Crtap, Dcstamp, Dkk1, Duoxa2, Enpp1, Fgf23, Kiss1/Kiss1r, Kl (Klotho), Lrp5, Mstn, Neo1, Npr2, Ostm1, Postn, Sfrp4, Slc30a5, Slc39a13, Sost, Sumf1, Src, Wnt10b), five novel genes extensively characterized (Cldn18, Fam20c, Lrrk1, Sgpl1, Wnt16), five novel genes with preliminary characterization (Agpat2, Rassf5, Slc10a7, Slc26a7, Slc30a10) and three novel undisclosed genes coding for potential osteoporosis drug targets.
Collapse
Affiliation(s)
| | - Jeff Liu
- Lexicon Pharmaceuticals , The Woodlands, TX, USA
| | | | | | | | | | | | | | - Peter Vogel
- Lexicon Pharmaceuticals , The Woodlands, TX, USA
| |
Collapse
|
43
|
Soleimani M. The multiple roles of pendrin in the kidney. Nephrol Dial Transplant 2014; 30:1257-66. [PMID: 25281699 DOI: 10.1093/ndt/gfu307] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 08/25/2014] [Indexed: 12/30/2022] Open
Abstract
The [Formula: see text] exchanger pendrin (SLC26A4, PDS) is located on the apical membrane of B-intercalated cells in the kidney cortical collecting duct and the connecting tubules and mediates the secretion of bicarbonate and the reabsorption of chloride. Given its dual function of bicarbonate secretion and chloride reabsorption in the distal tubules, it was thought that pendrin plays important roles in systemic acid-base balance and electrolyte and vascular volume homeostasis under basal conditions. Mice with the genetic deletion of pendrin or humans with inactivating mutations in PDS gene, however, do not display excessive salt and fluid wasting or altered blood pressure under baseline conditions. Very recent reports have unmasked the basis of incongruity between the mild phenotype in mutant mice and the role of pendrin as an important player in salt reabsorption in the distal tubule. These studies demonstrate that pendrin and the Na-Cl cotransporter (NCC; SLC12A3) cross compensate for the loss of each other, therefore masking the role that each transporter plays in salt reabsorption under baseline conditions. In addition, pendrin regulates calcium reabsorption in the distal tubules. Furthermore, combined deletion of pendrin and NCC not only causes severe volume depletion but also results in profound calcium wasting and luminal calcification in medullary collecting ducts. Based on studies in pathophysiological states and the examination of genetically engineered mouse models, the evolving picture points to important roles for pendrin (SLC26A4) in kidney physiology and in disease states. This review summarizes recent advances in the characterization of pendrin and the multiple roles it plays in the kidney, with emphasis on its essential roles in several diverse physiological processes, including chloride homeostasis, vascular volume and blood pressure regulation, calcium excretion and kidney stone formation.
Collapse
Affiliation(s)
- Manoocher Soleimani
- Center on Genetics of Transport and Epithelial Biology, University of Cincinnati, Cincinnati, OH, USA Research Services, Veterans Affairs Medical Center, Cincinnati, OH, USA Department of Medicine, University of Cincinnati, Cincinnati, OH, USA
| |
Collapse
|
44
|
Alka K, Casey JR. Bicarbonate transport in health and disease. IUBMB Life 2014; 66:596-615. [PMID: 25270914 DOI: 10.1002/iub.1315] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 09/10/2014] [Indexed: 12/28/2022]
Abstract
Bicarbonate (HCO3(-)) has a central place in human physiology as the waste product of mitochondrial energy production and for its role in pH buffering throughout the body. Because bicarbonate is impermeable to membranes, bicarbonate transport proteins are necessary to enable control of bicarbonate levels across membranes. In humans, 14 bicarbonate transport proteins, members of the SLC4 and SLC26 families, function by differing transport mechanisms. In addition, some anion channels and ZIP metal transporters contribute to bicarbonate movement across membranes. Defective bicarbonate transport leads to diseases, including systemic acidosis, brain dysfunction, kidney stones, and hypertension. Altered expression levels of bicarbonate transporters in patients with breast, colon, and lung cancer suggest an important role of these transporters in cancer.
Collapse
Affiliation(s)
- Kumari Alka
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | | |
Collapse
|
45
|
Kim KX, Sanneman JD, Kim HM, Harbidge DG, Xu J, Soleimani M, Wangemann P, Marcus DC. Slc26a7 chloride channel activity and localization in mouse Reissner's membrane epithelium. PLoS One 2014; 9:e97191. [PMID: 24810589 PMCID: PMC4014619 DOI: 10.1371/journal.pone.0097191] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 04/16/2014] [Indexed: 11/19/2022] Open
Abstract
Several members of the SLC26 gene family have highly-restricted expression patterns in the auditory and vestibular periphery and mutations in mice of at least two of these (SLC26A4 and SLC26A5) lead to deficits in hearing and/or balance. A previous report pointed to SLC26A7 as a candidate gene important for cochlear function. In the present study, inner ears were assayed by immunostaining for Slc26a7 in neonatal and adult mice. Slc26a7 was detected in the basolateral membrane of Reissner’s membrane epithelial cells but not neighboring cells, with an onset of expression at P5; gene knockout resulted in the absence of protein expression in Reissner’s membrane. Whole-cell patch clamp recordings revealed anion currents and conductances that were elevated for NO3− over Cl− and inhibited by I− and NPPB. Elevated NO3− currents were absent in Slc26a7 knockout mice. There were, however, no major changes to hearing (auditory brainstem response) of knockout mice during early adult life under constitutive and noise exposure conditions. The lack of Slc26a7 protein expression found in the wild-type vestibular labyrinth was consistent with the observation of normal balance. We conclude that SLC26A7 participates in Cl− transport in Reissner’s membrane epithelial cells, but that either other anion pathways, such as ClC-2, possibly substitute satisfactorily under the conditions tested or that Cl− conductance in these cells is not critical to cochlear function. The involvement of SLC26A7 in cellular pH regulation in other epithelial cells leaves open the possibility that SLC26A7 is needed in Reissner’s membrane cells during local perturbations of pH.
Collapse
Affiliation(s)
- Kyunghee X. Kim
- Anatomy & Physiology Department, Cellular Biophysics Laboratory, Kansas State University, Manhattan, Kansas, United States of America
| | - Joel D. Sanneman
- Anatomy & Physiology Department, Cell Physiology Laboratory, Kansas State University, Manhattan, Kansas, United States of America
| | - Hyoung-Mi Kim
- Anatomy & Physiology Department, Cell Physiology Laboratory, Kansas State University, Manhattan, Kansas, United States of America
| | - Donald G. Harbidge
- Anatomy & Physiology Department, Cellular Biophysics Laboratory, Kansas State University, Manhattan, Kansas, United States of America
| | - Jie Xu
- Department of Medicine and Center on Genetics of Transport, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Manoocher Soleimani
- Department of Medicine and Center on Genetics of Transport, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Philine Wangemann
- Anatomy & Physiology Department, Cell Physiology Laboratory, Kansas State University, Manhattan, Kansas, United States of America
| | - Daniel C. Marcus
- Anatomy & Physiology Department, Cellular Biophysics Laboratory, Kansas State University, Manhattan, Kansas, United States of America
- * E-mail:
| |
Collapse
|
46
|
|
47
|
Gil-Peña H, Mejía N, Santos F. Renal tubular acidosis. J Pediatr 2014; 164:691-698.e1. [PMID: 24345454 DOI: 10.1016/j.jpeds.2013.10.085] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 09/10/2013] [Accepted: 10/30/2013] [Indexed: 11/12/2022]
Affiliation(s)
- Helena Gil-Peña
- Division of Pediatric Nephrology, Hospital Universitario Central de Asturias, Oviedo, Spain; Department of Medicine, University of Oviedo, Oviedo, Spain
| | - Natalia Mejía
- Department of Pediatrics, University of Los Andes, Bogotá, Colombia
| | - Fernando Santos
- Division of Pediatric Nephrology, Hospital Universitario Central de Asturias, Oviedo, Spain; Department of Medicine, University of Oviedo, Oviedo, Spain.
| |
Collapse
|
48
|
Functional interaction of the cystic fibrosis transmembrane conductance regulator with members of the SLC26 family of anion transporters (SLC26A8 and SLC26A9): physiological and pathophysiological relevance. Int J Biochem Cell Biol 2014; 52:58-67. [PMID: 24530837 DOI: 10.1016/j.biocel.2014.02.001] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 01/29/2014] [Accepted: 02/01/2014] [Indexed: 12/21/2022]
Abstract
The solute carrier 26 (SLC26) proteins are transmembrane proteins located at the plasma membrane of the cells and transporting a variety of monovalent and divalent anions, including chloride, bicarbonate, sulfate and oxalate. In humans, 11 members have been identified (SLC26A1 to SLC26A11) and although part of them display a very restricted tissue expression pattern, altogether they are widely expressed in the epithelial cells of the body where they contribute to the composition and the pH regulation of the secreted fluids. Importantly, mutations in SLC26A2, A3, A4, and A5 have been associated with distinct human genetic recessive disorders (i.e. diastrophic dysplasia, congenital chloride diarrhea, Pendred syndrome and deafness, respectively), demonstrating their essential and non-redundant functions in many tissues. During the last decade, physical and functional interactions of SLC26 members with the cystic fibrosis transmembrane conductance regulator (CFTR) have been highly documented, leading to the model of a crosstalk based on the binding of the SLC26 STAS domain to the CFTR regulatory domain. In this review, we will focus on the functional interaction of SLC26A8 and SLC26A9 with the CFTR channel. In particular we will highlight the newly published studies indicating that mutations in SLC26A8 and SLC26A9 proteins are associated with a deregulation of the CFTR anion transport activity in the pathophysiological context of the sperm and the pulmonary cells. These studies confirm the physiological relevance of SLC26 and CFTR cross-regulation, opening new gates for the treatment of cystic fibrosis.
Collapse
|
49
|
Xu J, Barone S, Brooks MB, Soleimani M. Double knockout of carbonic anhydrase II (CAII) and Na(+)-Cl(-) cotransporter (NCC) causes salt wasting and volume depletion. Cell Physiol Biochem 2013; 32:173-83. [PMID: 24429824 PMCID: PMC10947769 DOI: 10.1159/000356637] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/21/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND AND AIMS The thiazide-sensitive Na(+)-Cl(-) cotransporter NCC and the Cl(-)/HCO3(-)exchanger pendrin are expressed on apical membranes of distal cortical nephron segments and mediate salt absorption, with pendrin working in tandem with the epithelial Na(+) channel (ENaC) and the Na(+)-dependent chloride/bicarbonate exchanger (NDCBE), whereas NCC is working by itself. A recent study showed that NCC and pendrin compensate for loss of each other under basal conditions, therefore masking the role that each plays in salt reabsorption. Carbonic anhydrase II (CAII, CA2 or CAR2) plays an important role in acid-base transport and salt reabsorption in the proximal convoluted tubule and acid-base transport in the collecting duct. Animals with CAII deletion show remodeling of intercalated cells along with the downregulation of pendrin. NCC KO mice on the other hand show significant upregulation of pendrin and ENaC. Neither model shows any significant salt wasting under baseline conditions. We hypothesized that the up-regulation of pendrin is essential for the prevention of salt wasting in NCC KO mice. METHODS AND RESULTS To test this hypothesis, we generated NCC/CAII double KO (dKO) mice by crossing mice with single deletion of NCC and CAII. The NCC/CAII dKO mice displayed significant downregulation of pendrin, along with polyuria and salt wasting. As a result, the dKO mice developed volume depletion, which was associated with the inability to concentrate urine. CONCLUSIONS We conclude that the upregulation of pendrin is essential for the prevention of salt and water wasting in NCC deficient animals and its downregulation or inactivation will result in salt wasting, impaired water conservation and volume depletion in the setting of NCC inactivation or inhibition.
Collapse
Affiliation(s)
- Jie Xu
- Research Services, Veterans Affairs Medical Center, University of Cincinnati
- Departments of Medicine, University of Cincinnati
| | - Sharon Barone
- Research Services, Veterans Affairs Medical Center, University of Cincinnati
- Departments of Medicine, University of Cincinnati
| | | | - Manoocher Soleimani
- Research Services, Veterans Affairs Medical Center, University of Cincinnati
- Departments of Medicine, University of Cincinnati
- Center on Genetics of Transport and Epithelial Biology, University of Cincinnati Cincinnati, OH, USA
| |
Collapse
|
50
|
Zahedi K, Barone S, Xu J, Soleimani M. Potentiation of the effect of thiazide derivatives by carbonic anhydrase inhibitors: molecular mechanisms and potential clinical implications. PLoS One 2013; 8:e79327. [PMID: 24260196 PMCID: PMC3832474 DOI: 10.1371/journal.pone.0079327] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 09/29/2013] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Carbonic anhydrase inhibitors (CAI) are mild diuretics, hence not widely used in fluid overloaded states. They are however the treatment of choice for certain non-kidney conditions. Thiazides, specific inhibitors of Na-Cl cotransport (NCC), are mild agents and the most widely used diuretics in the world for control of mild hypertension. HYPOTHESIS In addition to inhibiting the salt reabsorption in the proximal tubule, CAIs down-regulate pendrin, therefore leaving NCC as the major salt absorbing transporter in the distal nephron, and hence allowing for massive diuresis by the inhibitors of NCC in the setting of increased delivery of salt from the proximal tubule. EXPERIMENTAL PROTOCOLS AND RESULTS Daily treatment of rats with acetazolamide (ACTZ), a known CAI, for 10 days caused mild diuresis whereas daily treatment with hydrochlorothiazide (HCTZ) for 4 days caused hardly any diuresis. However, treatment of rats that were pretreated with ACTZ for 6 days with a combination of ACTZ plus HCTZ for 4 additional days increased the urine output by greater than 2 fold (p<0.001, n = 5) compared to ACTZ-treated animals. Sodium excretion increased by 80% in the ACTZ plus HCTZ group and animals developed significant volume depletion, metabolic alkalosis and pre-renal failure. Molecular studies demonstrated ∼75% reduction in pendrin expression by ACTZ. The increased urine output in ACTZ/HCTZ treated rats was associated with a significant reduction in urine osmolality and reduced membrane localization of AQP-2 (aquaporin2). CONCLUSIONS These results indicate that ACTZ down-regulates pendrin expression and leaves NCC as the major salt absorbing transporter in the distal nephron in the setting of increased delivery of salt from the proximal tubule. Despite being considered mild agents individually, we propose that the combination of ACTZ and HCTZ is a powerful diuretic regimen.
Collapse
Affiliation(s)
- Kamyar Zahedi
- Center on Genetics of Transport and the Department of Medicine, University of Cincinnati, Research Services, Veterans Affairs Medical Center, Cincinnati, Ohio
| | - Sharon Barone
- Center on Genetics of Transport and the Department of Medicine, University of Cincinnati, Research Services, Veterans Affairs Medical Center, Cincinnati, Ohio
| | - Jie Xu
- Center on Genetics of Transport and the Department of Medicine, University of Cincinnati, Research Services, Veterans Affairs Medical Center, Cincinnati, Ohio
| | - Manoocher Soleimani
- Center on Genetics of Transport and the Department of Medicine, University of Cincinnati, Research Services, Veterans Affairs Medical Center, Cincinnati, Ohio
- * E-mail:
| |
Collapse
|