Glande thyroïde

La glande thyroïde ou thyroïde est une glande endocrine régulant, chez les vertébrés, de nombreux systèmes hormonaux par la sécrétion de triiodothyronine (T3), de thyroxine (T4) et de calcitonine. Dans l'espèce humaine, elle est située à la face antérieure du cou, superficiellement. Ses déformations (on parle de goitre quand le volume de la thyroïde est augmenté) sont visibles sous la peau. Elle peut être le siège de diverses affections : hyperthyroïdie, hypothyroïdie, tumeur maligne ou tumeur bénigne. On peut l'étudier grâce à l'échographie et à la scintigraphie. Anatomie Morphologie La thyroïde, moulée sur l'axe trachéo-laryngé, est de consistance ferme, de couleur rosée, et pèse de 25 à généralement mais en cas de goitre sa masse peut augmenter jusqu'à 100-. Elle est entourée d'une capsule avasculaire (ou gaine viscérale péri-thyroïdienne) qui lui est propre et qui est différente de la loge thyroïdienne. La thyroïde se compose de deux lobes droit et ga

Circadian Clock Characteristics Are Altered in Human Thyroid Malignant Nodules

Olivia Mariani, Daniel Sage, Daniel Andreas Schmitter

Context: The circadian clock represents the body's molecular time-keeping system. Recent findings revealed strong changes of clock gene expression in various types of human cancers. Objective: Due to emerging evidence on the connection between the circadian oscillator, cell cycle, and oncogenic transformation, we aimed to characterize the circadian clockwork in human benign and malignant thyroid nodules. Design: Clock transcript levels were assessed by quantitative RT-PCR in thyroid tissues. To provide molecular characteristics of human thyroid clockwork, primary thyrocytes established from normal or nodular thyroid tissue biopsies were subjected to in vitro synchronization with subsequent clock gene expression analysis by circadian bioluminescence reporter assay and by quantitative RT-PCR. Results: The expression levels of the Bmal1 were up-regulated in tissue samples of follicular thyroid carcinoma (FTC), and in papillary thyroid carcinoma (PTC), as compared with normal thyroid and benign nodules, whereas Cry2 was down-regulated in FTC and PTC. Human thyrocytes derived from normal thyroid tissue exhibited high-amplitude circadian oscillations of Bmal1-luciferase reporter expression and endogenous clock transcripts. Thyrocytes established from FTC and PTC exhibited clock transcript oscillations similar to those of normal thyroid tissue and benign nodules (except for Per2 altered in PTC), whereas cells derived from poorly differentiated thyroid carcinoma exhibited altered circadian oscillations. Conclusions: This is the first study demonstrating a molecular makeup of the human thyroid circadian clock. Characterization of the thyroid clock machinery alterations upon thyroid nodule malignant transformation contributes to understanding the connections between circadian clocks and oncogenic transformation. Moreover, it might help in improving the thyroid nodule preoperative diagnostics.

Endocrine Soc2013

Retinoic acid signaling organizes endodermal organ specification along the entire antero-posterior axis

Anne Grapin-Botton

BACKGROUND: Endoderm organ primordia become specified between gastrulation and gut tube folding in Amniotes. Although the requirement for RA signaling for the development of a few individual endoderm organs has been established a systematic assessment of its activity along the entire antero-posterior axis has not been performed in this germ layer. METHODOLOGY/PRINCIPAL FINDINGS: RA is synthesized from gastrulation to somitogenesis in the mesoderm that is close to the developing gut tube. In the branchial arch region specific levels of RA signaling control organ boundaries. The most anterior endoderm forming the thyroid gland is specified in the absence of RA signaling. Increasing RA in anterior branchial arches results in thyroid primordium repression and the induction of more posterior markers such as branchial arch Hox genes. Conversely reducing RA signaling shifts Hox genes posteriorly in endoderm. These results imply that RA acts as a caudalizing factor in a graded manner in pharyngeal endoderm. Posterior foregut and midgut organ primordia also require RA, but exposing endoderm to additional RA is not sufficient to expand these primordia anteriorly. We show that in chick, in contrast to non-Amniotes, RA signaling is not only necessary during gastrulation, but also throughout gut tube folding during somitogenesis. Our results show that the induction of CdxA, a midgut marker, and pancreas induction require direct RA signaling in endoderm. Moreover, communication between CdxA(+) cells is necessary to maintain CdxA expression, therefore synchronizing the cells of the midgut primordium. We further show that the RA pathway acts synergistically with FGF4 in endoderm patterning rather than mediating FGF4 activity. CONCLUSIONS/SIGNIFICANCE: Our work establishes that retinoic acid (RA) signaling coordinates the position of different endoderm organs along the antero-posterior axis in chick embryos and could serve as a basis for the differentiation of specific endodermal organs from ES cells.

Public Library of Science2009

Retinoic acid signaling organizes endodermal organ specification along the entire antero-posterior axis

Anne Grapin-Botton

Public Library of Science2009

Circadian Clock Characteristics Are Altered in Human Thyroid Malignant Nodules

Olivia Mariani, Daniel Sage, Daniel Andreas Schmitter

Endocrine Soc2013

Identification of a novel modulator of thyroid hormone receptor-mediated action

Circadian Clock Characteristics Are Altered in Human Thyroid Malignant Nodules

Retinoic acid signaling organizes endodermal organ specification along the entire antero-posterior axis

Retinoic acid signaling organizes endodermal organ specification along the entire antero-posterior axis

Identification of a novel modulator of thyroid hormone receptor-mediated action

Circadian Clock Characteristics Are Altered in Human Thyroid Malignant Nodules