Dataset Information

Structure of Human Thyroglobulin

ABSTRACT: Thyroid hormones T3 and T4 play a crucial role in the regulation of vertebrate metabolism. The thyroglobulin (Tg) protein is key to thyroid hormone synthesis, and its structure is conserved among vertebrates. TgG is delivered through the secretory pathway to the lumen of the thyroid gland, where it is iodinated at specific tyrosine sites to form mono- or di-iodotyrosine, which combine to produce T3 and T4, respectively. The formation of these hormones depends on the precise 3D structure of thyroglobulin, which has remained unknown despite decades of research on this protein. Here, we present the cryo-electron microscopy structure of human thyroglobulin, to a global resolution of 3.2 Å. Our results offer structural insight into thyroid hormonogenesis and provide a framework to understand hundreds of clinically relevant mutations. The structure of hTg contributes to a better understanding and potentially improved treatment of thyroid hypothyroidism, thyroid cancer and other Tg disorders.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: Alexander Schmidt

LAB HEAD: Alexander Schmidt

PROVIDER: PXD018452 | Pride | 2022-02-24

REPOSITORIES: Pride

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Publications

Cryo-EM structure of native human thyroglobulin.

Adaixo Ricardo R Steiner Eva M EM Righetto Ricardo D RD Schmidt Alexander A Stahlberg Henning H Taylor Nicholas M I NMI

Nature communications 20220110 1

The thyroglobulin (TG) protein is essential to thyroid hormone synthesis, plays a vital role in the regulation of metabolism, development and growth and serves as intraglandular iodine storage. Its architecture is conserved among vertebrates. Synthesis of triiodothyronine (T<sub>3</sub>) and thyroxine (T<sub>4</sub>) hormones depends on the conformation, iodination and post-translational modification of TG. Although structural information is available on recombinant and deglycosylated endogenous ...[more]

PMID: 35013249

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Project description:Background: Thyroxine (T4) is generally considered to be a pro-hormone that requires conversion to 3,5,3’-triiodothyronine (T3) to exert biological activity. Although evidence suggests that T4 has intrinsic activity, it is questionable if this activity has any physiological relevance. Methods: To answer this question, triple KO mice (Triples) that cannot express the types 1 (D1) and 2 (D2) deiodinase and the Pax8 genes were generated. Thus they lack a thyroid and cannot convert T4 to T3. Triples were injected on alternate days with either vehicle or physiological doses of T4, T3 or T3+T4 from postnatal days 2 to 14. They were euthanized at P15 and RNA-seq was employed to profile gene expression in liver. In another experiment, Pax8KO mice were injected with T3, T4 or T4 +T3, and growth rate and survival to P84 were determined. Results: The growth retardation of Triples was not improved by either T3 or T4 alone but was significantly improved by T4+T3. In liver, T4 significantly regulated the expression of genes that were also regulated by T3, but the proportion of genes that were negatively regulated was higher in mice treated with T4 than with T3. Treatment with T4+T3 identified genes that were regulated synergistically by T3 and T4, and genes that were regulated only by T4+T3. Analysis of these genes revealed enrichment in mechanisms related to cell proliferation and cholesterol physiology, suggesting a unique contribution of T4 to these biological functions. Pax8KO mice all survived to P84 when injected with T4 or T4+T3 but survival rate with T3 was 50% and 10% at 3.5 and 12 weeks of life, respectively. Conclusion: T4 has intrinsic activity in vivo and is critical for survival and growth. At a physiological level, T4 per se can up- or down-regulate many T3 target genes in the neonatal liver. While most of these genes are also regulated by T3, subsets respond exclusively to T4 or demonstrate enhanced or normalized expression only in the presence of both hormones. These studies demonstrate for the first time a complex dependency on both T4 and T3 for normal mammalian growth and development.

Dataset Information

Structure of Human Thyroglobulin

Publications

Cryo-EM structure of native human thyroglobulin.

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