Perchlorate transport and inhibition of the sodium iodide symporter measured with the yellow fluorescent protein variant YFP-H148Q/I152L

Journal Article · Mon Mar 15 04:00:00 EDT 2010 · Toxicology and Applied Pharmacology

DOI:https://doi.org/10.1016/j.taap.2009.12.004· OSTI ID:21344895

Cianchetta, Stefano; Bernardo, Julie di; Romeo, Giovanni ^[1]

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1. Medical Genetics Unit, Department of Gynecologic, Obstetric and Pediatric Sciences, University of Bologna, Bologna (Italy)

Perchlorate is an environmental contaminant that impairs thyroid function by interacting with the sodium iodide symporter (NIS), the transporter responsible for iodide uptake in the thyroid gland. Perchlorate is well known as a competitive inhibitor of iodide transport by NIS, and recent evidence demonstrates that NIS can also transport perchlorate. In this study, we evaluated the yellow fluorescent protein (YFP) variant YFP-H148Q/I152L, as a genetically encodable biosensor of intracellular perchlorate concentration monitored by real-time fluorescence microscopy. Fluorescence of recombinant YFP-H148Q/I152L was suppressed by perchlorate and iodide with similar affinities of 1.2 mM and 1.6 mM, respectively. Perchlorate suppressed YFP-H148Q/I152L fluorescence in FRTL-5 thyroid cells and NIS-expressing COS-7 cells, but had no effect on COS-7 cells lacking NIS. Fluorescence changes in FRTL-5 cells were Na{sup +}-dependent, consistent with the Na{sup +}-dependence of NIS activity. Perchlorate uptake in FRTL-5 cells resulted in 10-fold lower intracellular concentrations than iodide uptake, and was characterized by a higher affinity (K{sub m} 4.6 muM for perchlorate and 34.8 muM for iodide) and lower maximal velocity (V{sub max} 6.8 muM/s for perchlorate and 39.5 muM/s for iodide). Perchlorate also prevented iodide-induced changes in YFP-H148Q/I152L fluorescence in FRTL-5 cells, with half-maximal inhibition occurring at 1.1-1.6 muM. In conclusion, YFP-H148Q/I152L detects perchlorate accumulation by thyroid and other NIS-expressing cells, and reveals differences in the kinetics of perchlorate versus iodide transport by NIS.

• OSTI ID: 21344895
• Journal Information: Toxicology and Applied Pharmacology, Journal Name: Toxicology and Applied Pharmacology Journal Issue: 3 Vol. 243; ISSN TXAPA9; ISSN 0041-008X
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
AFFINITY
ALKALI METAL COMPOUNDS
ANIMAL CELLS
BODY
CHARGED PARTICLES
CHLORINE COMPOUNDS
DRUGS
EMISSION
ENDOCRINE GLANDS
ESTERS
FLUORESCENCE
GLANDS
GLUTATHIONE
HALIDES
HALOGEN COMPOUNDS
INORGANIC PHOSPHORS
IODIDES
IODINE COMPOUNDS
IONS
KINETICS
LUMINESCENCE
ORGANIC COMPOUNDS
ORGANS
OXYGEN COMPOUNDS
PEPTIDES
PERCHLORATES
PHOSPHORS
PHOTON EMISSION
POLYPEPTIDES
PROTEINS
RADIOPROTECTIVE SUBSTANCES
RESPONSE MODIFYING FACTORS
SODIUM COMPOUNDS
SODIUM IODIDES
SODIUM IONS
SOMATIC CELLS
THYROID
THYROID CELLS