scholarly journals Identification and Characterization of a Putative Human Iodide Transporter Located at the Apical Membrane of Thyrocytes

2002 ◽  
Vol 87 (7) ◽  
pp. 3500-3503 ◽  
Author(s):  
Anne-Marie Rodriguez ◽  
Barbara Perron ◽  
Ludovic Lacroix ◽  
Bernard Caillou ◽  
Gérard Leblanc ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Human Kidney ◽  
Protein Product ◽  
Sodium Iodide Symporter ◽  
Pcr Cloning ◽  
Thyroid Cells ◽  
Iodide Transport ◽  
Acid Protein

Iodide transport by thyrocytes is a two step process involving transporters located either in the basal or in the apical membranes of the cell. The sodium iodide symporter (NIS) is localized in the basolateral membrane facing the bloodstream and mediates iodide accumulation into thyrocytes. Pendrin has been proposed as an apical transporter. In order to identify new iodide transporters, we developed a PCR cloning strategy based on NIS sequence homologies. From a human kidney cDNA library, we characterized a gene, located on chromosome 12q23, that encodes a 610 amino acid protein sharing 46% identity (70% similarity) with the human NIS. Functional analysis of the protein expressed in mammalian cells indicates that it catalyzes a passive iodide transport. The protein product was immunohistochemically localized at the apical pole of the thyroid cells facing the colloid lumen. These results suggest that this new identified protein mediates iodide transport from the thyrocyte into the colloid lumen through the apical membrane. It was designated hAIT for human Apical Iodide Transporter.

scholarly journals The BH3 Domain of Bcl-xS Is Required for Inhibition of the Antiapoptotic Function of Bcl-xL

1999 ◽  
Vol 19 (10) ◽  
pp. 6673-6681 ◽  
Author(s):  
Brian S. Chang ◽  
Ameeta Kelekar ◽  
Marian H. Harris ◽  
John E. Harlan ◽  
Stephen W. Fesik ◽  
...  
Keyword(s):  
Cell Death ◽  
Mammalian Cells ◽  
Mutational Analysis ◽  
Survival Function ◽  
Family Members ◽  
Protein Product ◽  
Deletion Mutants ◽  
Major Protein ◽  
Bh3 Domain ◽  
Acid Protein

ABSTRACT bcl-x is a member of the bcl-2 family of genes. The major protein product, Bcl-xL, is a 233-amino-acid protein which has antiapoptotic properties. In contrast, one of the alternatively spliced transcripts of the bcl-xgene codes for the protein Bcl-xS, which lacks 63 amino acids present in Bcl-xL and has proapoptotic activity. Unlike other proapoptotic Bcl-2 family members, such as Bax and Bak, Bcl-xS does not seem to induce cell death in the absence of an additional death signal. However, Bcl-xS does interfere with the ability of Bcl-xL to antagonize Bax-induced death in transiently transfected 293 cells. Mutational analysis of Bcl-xS was conducted to identify the domains necessary to mediate its proapoptotic phenotype. Deletion mutants of Bcl-xS which still contained an intact BH3 domain retained the ability to inhibit survival through antagonism of Bcl-xL. Bcl-xS was able to form heterodimers with Bcl-xL in mammalian cells, and its ability to inhibit survival correlated with the ability to heterodimerize with Bcl-xL. Deletion mutants of Bax and Bcl-2, which lacked BH1 and BH2 domains but contained a BH3 domain, were able to antagonize the survival effect conferred by Bcl-xL. The results suggest that BH3 domains from both pro- and antiapoptotic Bcl-2 family members, while lacking an intrinsic ability to promote programmed cell death, can be potent inhibitors of Bcl-xL survival function.

scholarly journals Decreased Expression of Thyroglobulin and Sodium Iodide Symporter Genes in Hashimoto’s Thyroiditis

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Anna Popławska-Kita ◽  
Beata Telejko ◽  
Katarzyna Siewko ◽  
Maria Kościuszko-Zdrodowska ◽  
Natalia Wawrusewicz-Kurylonek ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Hashimoto’S Thyroiditis ◽  
Sodium Iodide ◽  
Interleukin 1 ◽  
Thyroid Volume ◽  
Needle Aspiration ◽  
Hashimoto's Thyroiditis ◽  
Sodium Iodide Symporter ◽  
Thyroid Cells ◽  
Iodide Transport

Aim. The aim of the study was to compare the expression of sodium iodide symporter (NIS), thyroglobulin (Tg), tumor necrosis factor-α(TNFα), and interleukin-1βgenes in patients with Hashimoto’s thyroiditis (HT) and healthy individuals.Subjects and Methods.Thyroid cells were obtained from 39 patients with HT and 15 controls by an ultrasound guided fine needle aspiration biopsy.Results. The patients with HT had lower Tg and NIS mRNA (P=0.002andP=0.001, resp.), as well as higher TNFαmRNA expression (P=0.049) than the controls. In the HT group Tg mRNA expression correlated positively with NIS mRNA expression (R=0.739,P=0.0001) and thyroid volume (R=0.465,P=0.0005), as well as negatively with TNFαmRNA expression (R=-0.490,P=0.001) and anti-peroxidase antibodies (TPOAb) level (R=-0.482,P=0.0002), whereas NIS mRNA expression correlated positively with thyroid volume (R=0.319,P=0.02), as well as negatively with TNFαmRNA expression (R=-0.529,P=0.0006) and TPOAb level (R=-0.422,P=0.001).Conclusions.Our results suggest that decreased Tg and NIS expression in thyroid cells may result in reduced active iodide transport and reduced thyroid volume in patients with HT.

scholarly journals Pendrin Is an Iodide-Specific Apical Porter Responsible for Iodide Efflux from Thyroid Cells

2002 ◽  
Vol 87 (7) ◽  
pp. 3356-3361 ◽  
Author(s):  
Akio Yoshida ◽  
Shinichi Taniguchi ◽  
Ichiro Hisatome ◽  
Ines E. Royaux ◽  
Eric D. Green ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Transmembrane Protein ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Expression Vectors ◽  
Xenopus Laevis Oocytes ◽  
Sodium Iodide Symporter ◽  
Pendred Syndrome ◽  
Thyroid Cells ◽  
Rat Thyroid

The Pendred syndrome gene encodes a 780-amino acid putative transmembrane protein (pendrin) that is expressed in the apical membrane of thyroid follicular cells. Although pendrin was shown to transport iodide and chloride using Xenopus laevis oocytes and Sf9 insect cells, there is no report using mammalian cells to study its role in thyroid function. We show here, using COS-7 cells and Chinese hamster ovary cells transfected with expression vectors encoding sodium iodide symporter or human Pendred syndrome gene cDNA and by comparison with studies using rat thyroid FRTL-5 cells, that pendrin is an iodide-specific transporter in mammalian cells and is responsible for iodide efflux in the thyroid.

scholarly journals Cloning of the mouse sodium iodide symporter and its expression in the mammary gland and other tissues

2001 ◽  
Vol 170 (1) ◽  
pp. 185-196 ◽  
Author(s):  
B Perron ◽  
AM Rodriguez ◽  
G Leblanc ◽  
T Pourcher
Keyword(s):  
Mammary Gland ◽  
Mammalian Cells ◽  
Sodium Iodide ◽  
Distribution Analysis ◽  
Sodium Iodide Symporter ◽  
Iodide Uptake ◽  
Reading Frame ◽  
Hormone Synthesis ◽  
Iodide Transport ◽  
Lactating Mammary Gland

Iodide concentration in milk by mammals is a necessary step for thyroid hormone synthesis by the newborn. With the purpose of using the mouse as an animal model to analyse the role of the sodium iodide symporter (NIS) in iodide transport and its regulation in the mammary gland, mouse NIS (mNIS) cDNA was isolated from lactating mice. The cloned sequence shows an open reading frame of 1854 nucleotides encoding a protein of 618 amino acids highly homologous to the rat and human NIS (95% and 81% identity respectively). Expression of mNIS in cultured mammalian cells induced cellular iodide accumulation. This iodide uptake process is sodium dependent and inhibited by thiocyanate and perchlorate. Tissue distribution analysis revealed that mNIS mRNAs are predominantly expressed in thyroid, stomach and in the lactating mammary gland and are present to a lower extent in several other tissues. Our data show for the first time that the level of mNIS mRNA is upregulated in the mammary gland during lactation.

scholarly journals Characterization of Na+/H+ exchanger NHE8 in cultured renal epithelial cells

2007 ◽  
Vol 293 (3) ◽  
pp. F761-F766 ◽  
Author(s):  
Jianning Zhang ◽  
Ion Alexandru Bobulescu ◽  
Sunita Goyal ◽  
Peter S. Aronson ◽  
Michel G. Baum ◽  
...  
Keyword(s):  
Protein Expression ◽  
Mammalian Cells ◽  
Small Interfering Rna ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Functional Characterization ◽  
Protein Levels ◽  
Primary Amino ◽  
Interfering Rna

NHE8 is expressed in the apical membrane of the proximal tubule and is predicted to be a Na+/H+ exchanger on the basis of its primary amino acid sequence. Functional characterization of native NHE8 in mammalian cells has not been possible to date. We screened a number of polarized renal cell lines for the plasma membrane Na+/H+ exchangers (NHE1, 2, 3, 4, and 8) and found only NHE1 and NHE8 transcripts in NRK cells by RT-PCR. NHE8 protein is expressed in the apical membrane of NRK cells as demonstrated by immunoblots, confocal fluorescent immunocytochemistry, and immunoelectron microscopy. NHE1, on the other hand, is expressed primarily in the basolateral membrane. Bilateral perfusion of NRK cells grown on permeable supports shows Na+/H+ exchange activity on both the apical and basolateral membranes. NHE8-specific small interfering RNA knocks down NHE8 protein expression but does not affect NHE1 protein levels. Knockdown of NHE8 protein is accompanied by a commensurate reduction in apical NHE activity, without altered basolateral NHE activity. Conversely, transfection of NHE1-specific small interfering RNA knocks down NHE1 protein expression without affecting NHE8 protein levels and reduces basolateral NHE activity without affecting apical NHE activity. NHE8 is the only apical membrane Na+/H+ exchanger in NRK cells. NHE8 activity is Na+ dependent, displaying a cooperative sigmoidal relationship, and is highly sensitive to 5-( N-ethyl- n-isopropyl)-amiloride (EIPA). NRK cells provide a useful system where NHE8 can be studied in its native environment.

Ontogeny of rabbit renal cortical NHE3 and NHE1: effect of glucocorticoids

1995 ◽  
Vol 268 (5) ◽  
pp. F815-F820 ◽  
Author(s):  
M. Baum ◽  
D. Biemesderfer ◽  
D. Gentry ◽  
P. S. Aronson
Keyword(s):  
Proximal Tubule ◽  
Mammalian Cells ◽  
Renal Cortex ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Subcutaneous Administration ◽  
Mrna Abundance ◽  
Protein Abundance ◽  
Twofold Increase ◽  
Threefold Increase

The neonatal proximal tubule has a lower rate of bicarbonate absorption and Na+/H+ antiporter activity than the proximal tubule of adult animals. Two isoforms of the Na+/H+ antiporter have been localized to the proximal tubule. NHE3 is located on the apical membrane, whereas NHE1, the isoform found on most mammalian cells, is present on the basolateral membrane. The Na+/H+ antiporter isoforms that increase with renal maturation are unknown. The purpose of the present study was to examine the maturation of rabbit renal cortical NHE3 and NHE1 mRNA and protein abundance and to determine whether the rate of maturation of these isoforms was affected by glucocorticoids. Renal cortex from neonatal rabbits (1 wk) had approximately one-fourth the NHE3 mRNA and protein abundance as that from adult animals. Renal cortical NHE1 mRNA and protein abundance did not change significantly during maturation. Glucocorticoids have been shown to accelerate the maturation of neonatal bicarbonate absorption and apical membrane Na+/H+ antiporter activity. Daily subcutaneous administration of dexamethasone starting at 4 days of age (10 micrograms/100 g body wt) for 3 days and 2 h before being killed resulted in a twofold increase in NHE3 mRNA abundance and a threefold increase in NHE3 protein abundance. NHE1 mRNA and protein abundance were unaffected. These data show that there is selective maturation of NHE3 during renal cortical development, which can be accelerated by administration of glucocorticoids.

scholarly journals The sodium-bicarbonate cotransporter NBCe2 (slc4a5) expressed in human renal proximal tubules shows increased apical expression under high-salt conditions

2015 ◽  
Vol 309 (11) ◽  
pp. R1447-R1459 ◽  
Author(s):  
John J. Gildea ◽  
Peng Xu ◽  
Julia M. Carlson ◽  
Robert T. Gaglione ◽  
Dora Bigler Wang ◽  
...  
Keyword(s):  
Protein Expression ◽  
Sodium Bicarbonate ◽  
Apical Membrane ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Human Kidney ◽  
High Salt ◽  
Hek293 Cells ◽  
Bicarbonate Transport ◽  
Sodium Bicarbonate Cotransporter

The electrogenic sodium bicarbonate cotransporter (NBCe2) is encoded by SLC4A5, variants of which have been associated with salt sensitivity of blood pressure, which affects 25% of the adult population. NBCe2 is thought to mediate sodium bicarbonate cotransport primarily in the renal collecting duct, but NBCe2 mRNA is also found in the rodent renal proximal tubule (RPT). The protein expression or function of NBCe2 has not been demonstrated in the human RPT. We validated an NBCe2 antibody by shRNA and Western blot analysis, as well as overexpression of an epitope-tagged NBCe2 construct in both RPT cells (RPTCs) and human embryonic kidney 293 (HEK293) cells. Using this validated NBCe2 antibody, we found NBCe2 protein expression in the RPT of fresh and frozen human kidney slices, RPTCs isolated from human urine, and isolated RPTC apical membrane. Under basal conditions, NBCe2 was primarily found in the Golgi, while NBCe1 was primarily found at the basolateral membrane. Following an acute short-term increase in intracellular sodium, NBCe2 expression was increased at the apical membrane in cultured slices of human kidney and polarized, immortalized RPTCs. Sodium bicarbonate transport was increased by monensin and overexpression of NBCe2, decreased by NBCe2 shRNA, but not by NBCe1 shRNA, and blocked by 2,2′-(1,2-ethenediyl)bis[5-isothiocyanato-benzenesulfonic acid]. NBCe2 could be important in apical sodium and bicarbonate cotransport under high-salt conditions; the implication of the ex vivo studies to the in vivo situation when salt intake is increased remains unclear. Therefore, future studies will examine the role of NBCe2 in mediating increased renal sodium transport in humans whose blood pressures are elevated by an increase in sodium intake.

Stimulation by caveolin-1 of the hypotonicity-induced release of taurine and ATP at basolateral, but not apical, membrane of Caco-2 cells

2006 ◽  
Vol 290 (5) ◽  
pp. C1287-C1296 ◽  
Author(s):  
Nina Ullrich ◽  
Adrian Caplanusi ◽  
Bert Brône ◽  
Diane Hermans ◽  
Els Larivière ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Regulatory Volume Decrease ◽  
Protective Mechanism ◽  
Organic Osmolytes ◽  
Wild Type ◽  
Caveolin 1 ◽  
Water Efflux ◽  
Electrophysiological Characterization

Regulatory volume decrease (RVD) is a protective mechanism that allows mammalian cells to restore their volume when exposed to a hypotonic environment. A key component of RVD is the release of K+, Cl−, and organic osmolytes, such as taurine, which then drives osmotic water efflux. Previous experiments have indicated that caveolin-1, a coat protein of caveolae microdomains in the plasma membrane, promotes the swelling-induced Cl− current ( ICl,swell) through volume-regulated anion channels. However, it is not known whether the stimulation by caveolin-1 is restricted to the release of Cl− or whether it also affects the swelling-induced release of other components, such as organic osmolytes. To address this problem, we have studied ICl,swell and the hypotonicity-induced release of taurine and ATP in wild-type Caco-2 cells that are caveolin-1 deficient and in stably transfected Caco-2 cells that express caveolin-1. Electrophysiological characterization of wild-type and stably transfected Caco-2 showed that caveolin-1 promoted ICl,swell, but not cystic fibrosis transmembrane conductance regulator currents. Furthermore, caveolin-1 expression stimulated the hypotonicity-induced release of taurine and ATP in stably transfected Caco-2 cells grown as a monolayer. Interestingly, the effect of caveolin-1 was polarized because only the release at the basolateral membrane, but not at the apical membrane, was increased. It is therefore concluded that caveolin-1 facilitates the hypotonicity-induced release of Cl−, taurine, and ATP, and that in polarized epithelial cells, the effect of caveolin-1 is compartmentalized to the basolateral membrane.

scholarly journals Immunoanalysis indicates that the sodium iodide symporter is not overexpressed in intracellular compartments in thyroid and breast cancers

2009 ◽  
Vol 160 (2) ◽  
pp. 215-225 ◽  
Author(s):  
Isabelle Peyrottes ◽  
Valerie Navarro ◽  
Alejandro Ondo-Mendez ◽  
Didier Marcellin ◽  
Laurent Bellanger ◽  
...  
Keyword(s):  
Western Blot ◽  
Specific Binding ◽  
Basolateral Membrane ◽  
Breast Cancers ◽  
Sodium Iodide Symporter ◽  
Intracellular Staining ◽  
Thyroid Cells ◽  
Breast Tumours ◽  
Intracellular Compartments ◽  
Initial Objective

ObjectiveThe active transport of iodide into thyroid cells is mediated by the Na+/I− symporter (NIS) located in the basolateral membrane. Strong intracellular staining with anti-NIS antibodies has been reported in thyroid and breast cancers. Our initial objective was to screen tumour samples for intracellular NIS staining and then to study the mechanisms underlying the altered subcellular localization of the transporters.MethodsImmunostaining using three different anti-NIS antibodies was performed on paraffin-embedded tissue sections from 93 thyroid or breast cancers. Western blot experiments were carried out to determine the amount of NIS protein in 20 samples.ResultsUsing three different anti-NIS antibodies, we observed intracellular staining in a majority of thyroid tumour samples. Control immunohistochemistry and western blot experiments indicated that this intracellular staining was due to non-specific binding of the antibodies. In breast tumours, very weak intracellular staining was observed in some samples. Western blot experiments suggest that this labelling is also non-specific.ConclusionsOur results strongly indicate that the NIS protein level is low in thyroid and breast cancers and that the intracellular staining obtained with anti-NIS antibodies corresponds to a non-specific signal. Accordingly, to increase the efficiency of radiotherapy for thyroid cancers and to enable the use of radioiodine in the diagnosis and therapy of breast tumours, improving NIS targeting to the plasma membrane will not be sufficient. Instead, increasing the expression level of NIS should remain the major goal of this field.

scholarly journals Modulation of sodium iodide symporter expression and function by LY294002, Akti-1/2 and Rapamycin in thyroid cells

2012 ◽  
Vol 19 (3) ◽  
pp. 291-304 ◽  
Author(s):  
Yu-Yu Liu ◽  
Xiaoli Zhang ◽  
Matthew D Ringel ◽  
Sissy M Jhiang
Keyword(s):  
Sodium Iodide Symporter ◽  
Efflux Rate ◽  
Iodide Uptake ◽  
Thyroid Cells ◽  
Thyroid Cancers ◽  
Protein Levels ◽  
Iodide Transport ◽  
Pi3k Inhibition ◽  
And Function ◽  
Selective Increase

The selective increase of Na+/I−symporter (NIS)-mediated active iodide uptake in thyroid cells allows the use of radioiodine I131for diagnosis and targeted treatment of thyroid cancers. However, NIS-mediated radioiodine accumulation is often reduced in thyroid cancers due to decreased NIS expression/function. As PI3K signaling is overactivated in many thyroid tumors, we investigated the effects of inhibitors for PI3K, Akt, or mTORC1 as well as their interplay on NIS modulation in thyroid cells under chronic TSH stimulation. PI3K inhibition by LY294002 increased NIS-mediated radioiodide uptake (RAIU) mainly through upregulation of NIS expression, however, mTORC1 inhibition by Rapamycin did not increase NIS-mediated RAIU despite increased NIS protein levels. In comparison, Akt inhibition by Akti-1/2 did not increase NIS protein levels, yet markedly increased NIS-mediated RAIU by decreasing iodide efflux rate and increasing iodide transport rate and iodide affinity of NIS. The effects of Akti-1/2 on NIS-mediated RAIU are not detected in nonthyroid cells, implying that Akti-1/2 or its derivatives may represent potential pharmacological reagents to selectively increase thyroidal radioiodine accumulation and therapeutic efficacy.

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