Screening for mutations of the human thyroid peroxidase gene in patients with congenital hypothyroidism

Objective: Defects in the human thyroid peroxidase (TPO) gene are reported to be one of the causes of congenital hypothyroidism (CH) due to a total iodide organification defect. The aim of the present study was to determine the nature and frequency of TPO gene mutations in patients with CH, characterised by elevated TSH levels and orthotopic thyroid gland, identified in the Portuguese National Neonatal Screening Programme. Subjects and methods: The sample comprised 55 patients, from 53 unrelated families, with follow-up in the endocrinology clinics of the treatment centres of Porto and Lisbon. Mutation screening in the TPO gene (exons 1–17) was performed by single-strand conformational analysis followed by sequencing of fragments with abnormal migration patterns. Results: Eight different mutations were detected in 13 patients (seven homozygotes and six compound heterozygotes). Novel mutations included three missense mutations, namely 391T > C (S131P), 1274A > G (N425S) and 2512T > A (C838S), as well as the predictable splice mutation 2748G > A (Q916Q/spl?). The undocumented polymorphism 180-47A > C was also detected. Conclusion: The results are in accordance with previous observations confirming the genetic heterogeneity of TPO defects. The proportion of patients in which the aetiology was determined justifies the implementation of this molecular testing in our CH patients with dyshormonogenesis.

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Inhibition of human thyroid peroxidase gene expression by interleukin 1

Acta Endocrinologica ◽

10.1530/acta.0.1210465 ◽

1989 ◽

Vol 121 (4) ◽

pp. 465-469 ◽

Cited By ~ 21

Author(s):

Kiyoto Ashizawa ◽

Shunichi Yamashita ◽

Tamami Tobinaga ◽

Yuji Nagayama ◽

Hironori Kimura ◽

...

Keyword(s):

Gene Expression ◽

Interleukin 1 ◽

Mrna Level ◽

Inhibitory Effect ◽

Human Thyroid ◽

Thyroid Peroxidase ◽

Hormone Synthesis ◽

Peroxidase Gene ◽

Camp Analogue ◽

Human Thyroid Peroxidase

Abstract. We have already demonstrated the inhibitory effect of interleukin 1 on thyroglobulin gene expression. Recent availability of thyroid peroxidase cDNA has allowed us to investigate the regulation of thyroid peroxidase gene. Therefore, the regulation of thyroid peroxidase mRNA by interleukin 1 in cultured human thyrocytes was investigated. Thyrocytes dispersed from thyroid tissues from patients with Graves' disease were incubated with TSH with or withtout recombinant human interleukin 1. Unstimulated human thyrocytes did not contain any detectable thyroid peroxidase mRNA, however, TSH-stimulated thyrocytes expressed four thyroid peroxidase mRNA transcripts (4.0, 3.2, 2.1 and 1.7 kb, respectively). Both interleukin 1 α and β inhibited TSH-induced thyroid peroxidase mRNA in a dose responsive manner; 103 U/l interleukin l caused maximal suppression of TSH-induced thyroid peroxidase mRNA level to nearly basal levels. Interleukin l also inhibited cAMP analogue 8-bromo-cyclic AMP induced thyroid peroxidase mRNA level. In contrast the γ-actin mRNA hybridization signal was not altered in control or treated cells. These results demonstrate that interleukin 1 directly inhibits TSH-induced thyroid peroxidase gene expression and provide further evidence for a paracrine role of interleukin 1 as a local inhibitor of thyroid hormone synthesis.

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Thyroid-specific enhancer-binding protein (T/EBP): cDNA cloning, functional characterization, and structural identity with thyroid transcription factor TTF-1

Molecular and Cellular Biology ◽

10.1128/mcb.11.10.4927-4933.1991 ◽

1991 ◽

Vol 11 (10) ◽

pp. 4927-4933

Author(s):

K Mizuno ◽

F J Gonzalez ◽

S Kimura

Keyword(s):

Transcription Factor ◽

Hepg2 Cells ◽

Human Thyroid ◽

Thyroid Peroxidase ◽

Enhancer Activity ◽

Cis Acting ◽

Peroxidase Gene ◽

Enhancer Binding Protein ◽

Human Thyroid Peroxidase ◽

Double Stranded Oligonucleotide

A cDNA clone encoding a thyroid-specific enhancer-binding protein (T/EBP) was isolated from a rat thyroid-derived FRTL-5 cell lambda gt 11 expression library, using a double-stranded oligonucleotide probe. This oligonucleotide was previously demonstrated to have the strongest binding affinity among three cis-acting DNA elements within the thyroid-specific enhancer region located 5.5 kbp upstream of the human thyroid peroxidase gene transcription start site. Nucleotide and deduced amino acid sequences of the cDNA revealed that T/EBP is identical to the previously reported thyroid-specific transcription factor 1 (TTF-1), which binds to the promoter of the rat thyroglobulin gene and controls its thyroid-specific expression. Expression of the T/EBP cDNA under control of the human cytomegalovirus major immediate-early gene promoter conferred thyroid-specific enhancer activity of as high as 26-fold to nonpermissive human hepatoma HepG2 cells when cotransfected with a vector containing 6.3 kbp of upstream sequence of the human thyroid peroxidase gene connected to a luciferase reporter gene. T/EBP was further expressed in HepG2 cells by using the vaccinia virus expression system. The expressed protein was partially purified by using sequence-specific affinity column chromatography and was further shown, by gel mobility shift experiments, to specifically bind to the enhancer-derived double-stranded oligonucleotide. These results clearly indicate that the binding of T/EBP (TTF-1) to the specific cis-acting enhancer element is largely responsible for thyroid-specific enhancer activity.

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Iodide uptake in human anaplastic thyroid carcinoma cells after transfer of the human thyroid peroxidase gene

European Journal of Nuclear Medicine ◽

10.1007/s002590100507 ◽

2001 ◽

Vol 28 (5) ◽

pp. 633-638 ◽

Cited By ~ 20

Author(s):

Uwe Haberkorn ◽

Annette Altmann ◽

Shiming Jiang ◽

Iris Morr ◽

Miriam Mahmut ◽

...

Keyword(s):

Thyroid Carcinoma ◽

Anaplastic Thyroid Carcinoma ◽

Carcinoma Cells ◽

Human Thyroid ◽

Thyroid Peroxidase ◽

Iodide Uptake ◽

Peroxidase Gene ◽

Human Thyroid Peroxidase

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Thyroid-specific enhancer-binding protein (T/EBP): cDNA cloning, functional characterization, and structural identity with thyroid transcription factor TTF-1.

Molecular and Cellular Biology ◽

10.1128/mcb.11.10.4927 ◽

1991 ◽

Vol 11 (10) ◽

pp. 4927-4933 ◽

Cited By ~ 85

Author(s):

K Mizuno ◽

F J Gonzalez ◽

S Kimura

Keyword(s):

Transcription Factor ◽

Hepg2 Cells ◽

Human Thyroid ◽

Thyroid Peroxidase ◽

Enhancer Activity ◽

Cis Acting ◽

Peroxidase Gene ◽

Enhancer Binding Protein ◽

Human Thyroid Peroxidase ◽

Double Stranded Oligonucleotide

A cDNA clone encoding a thyroid-specific enhancer-binding protein (T/EBP) was isolated from a rat thyroid-derived FRTL-5 cell lambda gt 11 expression library, using a double-stranded oligonucleotide probe. This oligonucleotide was previously demonstrated to have the strongest binding affinity among three cis-acting DNA elements within the thyroid-specific enhancer region located 5.5 kbp upstream of the human thyroid peroxidase gene transcription start site. Nucleotide and deduced amino acid sequences of the cDNA revealed that T/EBP is identical to the previously reported thyroid-specific transcription factor 1 (TTF-1), which binds to the promoter of the rat thyroglobulin gene and controls its thyroid-specific expression. Expression of the T/EBP cDNA under control of the human cytomegalovirus major immediate-early gene promoter conferred thyroid-specific enhancer activity of as high as 26-fold to nonpermissive human hepatoma HepG2 cells when cotransfected with a vector containing 6.3 kbp of upstream sequence of the human thyroid peroxidase gene connected to a luciferase reporter gene. T/EBP was further expressed in HepG2 cells by using the vaccinia virus expression system. The expressed protein was partially purified by using sequence-specific affinity column chromatography and was further shown, by gel mobility shift experiments, to specifically bind to the enhancer-derived double-stranded oligonucleotide. These results clearly indicate that the binding of T/EBP (TTF-1) to the specific cis-acting enhancer element is largely responsible for thyroid-specific enhancer activity.

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