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Human Sperm Capacitation Involves the Regulation of the Tyr-Phosphorylation Level of the Anion Exchanger 1 (AE1). Int J Mol Sci 2020; 21:ijms21114063. [PMID: 32517126 PMCID: PMC7311965 DOI: 10.3390/ijms21114063] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 06/02/2020] [Accepted: 06/03/2020] [Indexed: 12/22/2022] Open
Abstract
Bicarbonate uptake is one of the early steps of capacitation, but the identification of proteins regulating anion fluxes remains elusive. The aim of this study is to investigate the role of sperm solute carrier 4 (SLC4) A1 (spAE1) in the capacitation process. The expression, location, and tyrosine-phosphorylation (Tyr-P) level of spAE1 were assessed. Thereby, it was found that 4,4′-Diisothiocyano-2,2′-stilbenedisulfonic acid (DIDS), an SLC4 family channel blocker, inhibited capacitation in a dose-dependent manner by decreasing acrosome reaction (ARC% 24.5 ± 3.3 vs. 64.9 ± 4.3, p < 0.05) and increasing the percentage of not viable cells (NVC%), comparable to the inhibition by I-172, a cystic fibrosis transmembrane conductance regulator (CFTR) blocker (AR% 30.5 ± 4.4 and NVC% 18.6 ± 2.2). When used in combination, a synergistic inhibitory effect was observed with a remarkable increase of the percentage of NVC (45.3 ± 4.1, p < 0.001). spAE1 was identified in sperm membrane as a substrate for Tyr-protein kinases Lyn and Syk, which were identified as both soluble and membrane-bound pools. spAE1-Tyr-P level increased in the apical region of sperm under capacitating conditions and was negatively affected by I-172 or DIDS, and, to a far greater extent, by a combination of both. In conclusion, we demonstrated that spAE1 is expressed in sperm membranes and it is phosphorylated by Syk, but above all by Lyn on Tyr359, which are involved in sperm viability and capacitation.
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Ishii J, Suzuki A, Kimura T, Tateyama M, Tanaka T, Yazawa T, Arimasu Y, Chen IS, Aoyama K, Kubo Y, Saitoh S, Mizuno H, Kamma H. Congenital goitrous hypothyroidism is caused by dysfunction of the iodide transporter SLC26A7. Commun Biol 2019; 2:270. [PMID: 31372509 PMCID: PMC6656751 DOI: 10.1038/s42003-019-0503-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 06/13/2019] [Indexed: 12/27/2022] Open
Abstract
Iodide transport and storage in the thyroid follicles is crucial for thyroid hormone synthesis. Pendrin, the iodide exporter that transports iodide to thyroid follicles, is responsible for Pendred syndrome, a disorder characterized by congenital hypothyroidism and hearing loss. However, thyroid hormone levels are basically normal in patients with Pendred syndrome, indicating the presence of another unknown iodide transporter. Here, we show that SLC26A7 is a novel iodide transporter in the thyroid. We observe that SLC26A7 is specifically expressed in normal thyroid tissues and demonstrate its function in iodide transport. Using whole-exome sequencing, we also find a homozygous nonsense mutation in SLC26A7 (c.1498 C > T; p.Gln500Ter) in two siblings with congenital goitrous hypothyroidism. The mutated SLC26A7 protein shows an abnormal cytoplasmic localisation and lacks the iodide transport function. These results reveal that SLC26A7 functions as a novel iodide transporter in the thyroid and its dysfunction affects thyroid hormonogenesis in humans and causes congenital goitrous hypothyroidism.
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Affiliation(s)
- Jun Ishii
- Department of Pathology, Kyorin University School of Medicine, Tokyo, Japan
- Department of Pathology, Dokkyo Medical University, Tochigi, Japan
| | - Atsushi Suzuki
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Toru Kimura
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Tokyo, Japan
| | - Michihiro Tateyama
- Division of Biophysics and Neurobiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, Okazaki, Japan
| | - Tatsushi Tanaka
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Takuya Yazawa
- Department of Pathology, Dokkyo Medical University, Tochigi, Japan
| | - Yu Arimasu
- Department of Pathology, Kyorin University School of Medicine, Tokyo, Japan
| | - I-Shan Chen
- Division of Biophysics and Neurobiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, Okazaki, Japan
| | - Kohei Aoyama
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Yoshihiro Kubo
- Division of Biophysics and Neurobiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, Okazaki, Japan
| | - Shinji Saitoh
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Haruo Mizuno
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
- Department of Pediatrics, International University of Health and Welfare, School of Medicine, Narita, Japan
| | - Hiroshi Kamma
- Department of Pathology, Kyorin University School of Medicine, Tokyo, Japan
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CK2 is a key regulator of SLC4A2-mediated Cl -/HCO 3- exchange in human airway epithelia. Pflugers Arch 2017; 469:1073-1091. [PMID: 28455748 PMCID: PMC5554290 DOI: 10.1007/s00424-017-1981-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 03/27/2017] [Accepted: 04/10/2017] [Indexed: 12/17/2022]
Abstract
Transepithelial bicarbonate secretion by human airway submucosal glands and surface epithelial cells is crucial to maintain the pH-sensitive innate defence mechanisms of the lung. cAMP agonists stimulate HCO3- secretion via coordinated increases in basolateral HCO3- influx and accumulation, as well as CFTR-dependent HCO3- efflux at the luminal membrane of airway epithelial cells. Here, we investigated the regulation of a basolateral located, DIDS-sensitive, Cl-/HCO3- exchanger, anion exchanger 2 (AE2; SLC4A2) which is postulated to act as an acid loader, and therefore potential regulator of HCO3- secretion, in human airway epithelial cells. Using intracellular pH measurements performed on Calu-3 cells, we demonstrate that the activity of the basolateral Cl-/HCO3- exchanger was significantly downregulated by cAMP agonists, via a PKA-independent mechanism and also required Ca2+ and calmodulin under resting conditions. AE2 contains potential phosphorylation sites by a calmodulin substrate, protein kinase CK2, and we demonstrated that AE2 activity was reduced in the presence of CK2 inhibition. Moreover, CK2 inhibition abolished the activity of AE2 in primary human nasal epithelia. Studies performed on mouse AE2 transfected into HEK-293T cells confirmed almost identical Ca2+/calmodulin and CK2 regulation to that observed in Calu-3 and primary human nasal cells. Furthermore, mouse AE2 activity was reduced by genetic knockout of CK2, an effect which was rescued by exogenous CK2 expression. Together, these findings are the first to demonstrate that CK2 is a key regulator of Cl--dependent HCO3- export at the serosal membrane of human airway epithelial cells.
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Romero MF, Chen AP, Parker MD, Boron WF. The SLC4 family of bicarbonate (HCO₃⁻) transporters. Mol Aspects Med 2013; 34:159-82. [PMID: 23506864 DOI: 10.1016/j.mam.2012.10.008] [Citation(s) in RCA: 239] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 08/28/2012] [Indexed: 01/13/2023]
Abstract
The SLC4 family consists of 10 genes (SLC4A1-5; SLC4A7-11). All encode integral membrane proteins with very similar hydropathy plots-consistent with 10-14 transmembrane segments. Nine SLC4 members encode proteins that transport HCO3(-) (or a related species, such as CO3(2-)) across the plasma membrane. Functionally, eight of these proteins fall into two major groups: three Cl-HCO3 exchangers (AE1-3) and five Na(+)-coupled HCO3(-) transporters (NBCe1, NBCe2, NBCn1, NBCn2, NDCBE). Two of the Na(+)-coupled transporters (NBCe1, NBCe2) are electrogenic; the other three Na(+)-coupled HCO3(-) transporters and all three AEs are electroneutral. In addition, two other SLC4 members (AE4, SLC4A9 and BTR1, SLC4A11) do not yet have a firmly established function. Most, though not all, SLC4 members are functionally inhibited by 4,4'-diisothiocyanatostilbene-2,2'-disulfonate (DIDS). SLC4 proteins play important roles many modes of acid-base homeostasis: the carriage of CO2 by erythrocytes, the transport of H(+) or HCO3(-) by several epithelia, as well as the regulation of cell volume and intracellular pH.
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Affiliation(s)
- Michael F Romero
- Physiology & Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
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Parker MD, Boron WF. The divergence, actions, roles, and relatives of sodium-coupled bicarbonate transporters. Physiol Rev 2013; 93:803-959. [PMID: 23589833 PMCID: PMC3768104 DOI: 10.1152/physrev.00023.2012] [Citation(s) in RCA: 197] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The mammalian Slc4 (Solute carrier 4) family of transporters is a functionally diverse group of 10 multi-spanning membrane proteins that includes three Cl-HCO3 exchangers (AE1-3), five Na(+)-coupled HCO3(-) transporters (NCBTs), and two other unusual members (AE4, BTR1). In this review, we mainly focus on the five mammalian NCBTs-NBCe1, NBCe2, NBCn1, NDCBE, and NBCn2. Each plays a specialized role in maintaining intracellular pH and, by contributing to the movement of HCO3(-) across epithelia, in maintaining whole-body pH and otherwise contributing to epithelial transport. Disruptions involving NCBT genes are linked to blindness, deafness, proximal renal tubular acidosis, mental retardation, and epilepsy. We also review AE1-3, AE4, and BTR1, addressing their relevance to the study of NCBTs. This review draws together recent advances in our understanding of the phylogenetic origins and physiological relevance of NCBTs and their progenitors. Underlying these advances is progress in such diverse disciplines as physiology, molecular biology, genetics, immunocytochemistry, proteomics, and structural biology. This review highlights the key similarities and differences between individual NCBTs and the genes that encode them and also clarifies the sometimes confusing NCBT nomenclature.
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Affiliation(s)
- Mark D Parker
- Dept. of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Ave., Cleveland, OH 44106-4970, USA.
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Toczyłowska-Mamińska R, Dołowy K. Ion transporting proteins of human bronchial epithelium. J Cell Biochem 2012; 113:426-32. [PMID: 21975871 DOI: 10.1002/jcb.23393] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The electrolyte transport system across human airway epithelium followed by water movement is essential for the normal mucociliary clearance that allows the maintenance of the aseptic condition of the respiratory tract. The function of epithelial cells is to control and regulate ionic composition and volume of fluids in the airways. Various types of proteins taking part in assuring effective ions and water transport in apical and basolateral membranes of the airway epithelium have been found (e.g., CFTR, ENaC, CaCC, ORCC, potassium channels, NaKATPase, aquaporins). The paper reviews the current state of the art in the field of ion channels, transporters, and other signaling proteins identified in the human bronchial epithelium.
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Affiliation(s)
- Renata Toczyłowska-Mamińska
- Department of Biophysics, Warsaw University of Life Sciences (SGGW), 159 Nowoursynowska St, 0-776 Warsaw, Poland.
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Falkenberg CV, Jakobsson E. A biophysical model for integration of electrical, osmotic, and pH regulation in the human bronchial epithelium. Biophys J 2010; 98:1476-85. [PMID: 20409466 DOI: 10.1016/j.bpj.2009.11.045] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2009] [Revised: 11/11/2009] [Accepted: 11/19/2009] [Indexed: 12/14/2022] Open
Abstract
A dynamical biophysical model for the functioning of an epithelium is presented. This model integrates the electrical and osmotic behaviors of the epithelium, taking into account intracellular conditions. The specific tissue modeled is the human bronchial epithelium, which is of particular interest, as it is the location of the most common lethal symptoms of cystic fibrosis. The model is implemented in a modular form to facilitate future application of the code to other epithelial tissue by inputting different transporters, channels, and geometric parameters. The model includes pH regulation as an integral component of overall regulation of epithelial function, through the interdependence of pH, bicarbonate concentration, and current. The procedures for specification, the validation of the model, and parametric studies are presented using available experimental data of cultured human bronchial epithelium. Parametric studies are performed to elucidate a), the contribution of basolateral chloride channels to the short-circuit current functional form, and b), the role that regulation of basolateral potassium conductance plays in epithelial function.
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Affiliation(s)
- Cibele V Falkenberg
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
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Johnson M, Allen L, Dobbs L. Characteristics of Cl- uptake in rat alveolar type I cells. Am J Physiol Lung Cell Mol Physiol 2009; 297:L816-27. [PMID: 19684200 DOI: 10.1152/ajplung.90466.2008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although Cl- transport in fetal lung is important for fluid secretion and normal lung development, the role of Cl- transport in adult lung is not well understood. In physiological studies, the cystic fibrosis transmembrane regulator (CFTR) plays a role in fluid absorption in the distal air spaces of adult lung, and alveolar type II cells cultured for 5 days have the capacity to transport Cl-. Although both alveolar type I and type II cells express CFTR, it has previously not been known whether type I cells transport Cl-. We studied Cl- uptake in isolated type I cells directly, using either radioisotopic tracers or halide-sensitive fluorescent indicators. By both methods, type I cells take up Cl-. In the presence of beta-adrenergic agonist stimulation, Cl- uptake can be inhibited by CFTR antagonists. Type I cells express both the Cl-/HCO3- anion exchanger AE2 and the voltage-gated Cl- channels CLC5 and CLC2. Inhibitors of AE2 also block Cl- uptake in type I cells. Together, these results demonstrate that type I cells are capable of Cl- uptake and suggest that the effects seen in whole lung studies establishing the importance of Cl- movement in alveolar fluid clearance may be, in part, the result of Cl- transport across type I cells.
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Affiliation(s)
- Meshell Johnson
- Department of Medicine, University of California, San Francisco, 3333 California St., Suite 150, Box 1245, San Francisco, CA 94118, USA.
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