Related Experiment Video
Updated: May 28, 2026

03:57
Generation of Hypoparathyroid Rats via Carbon-Nanoparticle-Assisted Parathyroidectomy
Published on: July 14, 2023
PITX2 AND PITX1 regulate thyrotroph function and response to hypothyroidism
F Castinetti1, M L Brinkmeier, D F Gordon
1Department of Human Genetics, University of Michigan, Ann Arbor, USA.
Molecular Endocrinology (Baltimore, Md.)
|October 4, 2011
Summary
Pitx2 is crucial for pituitary development. Thyrotroph-specific Pitx2 deletion in mice revealed overlapping roles with Pitx1 in thyroid hormone regulation and response to hypothyroidism.
Area of Science:
- Endocrinology
- Molecular Biology
- Developmental Biology
Background:
- Pitx2 is a homeodomain transcription factor essential for pituitary and organ development.
- Pitx2 plays a dose-dependent role, with null mutations causing severe pituitary hypoplasia.
- Pitx2 is expressed in the fetal pituitary and adult thyrotrophs and gonadotrophs.
Purpose of the Study:
- To investigate the specific role of Pitx2 in thyrotroph function.
- To develop a thyrotroph-specific Cre transgenic mouse model for gene ablation.
- To elucidate the interplay between Pitx2 and Pitx1 in thyroid hormone regulation.
Main Methods:
- Generation of thyrotroph-specific Pitx2-deficient mice (Pitx2(flox/-);Tg(Tshb-cre)).
- Utilized a novel Tg(Tshb-Cre) bacterial artificial chromosome.
- Confirmed Pitx2 deletion via double immunohistochemistry.
- Assessed thyroid gland size, circulating hormone levels (T4, TSH), and Pitx1 transcript levels.
- Induced hypothyroidism using a low-iodine diet and propylthiouracil.
Main Results:
- Thyrotroph-specific Pitx2 deficiency resulted in smaller thyroid glands but normal circulating T4 and TSH levels.
- Pituitary Pitx1 transcript levels were significantly increased in Pitx2-deficient mice, suggesting compensation.
- Pitx2-deficient mice exhibited a blunted TSH response to induced hypothyroidism.
- Pitx1 upregulation in response to hypothyroidism was abolished in Pitx2-deficient mice.
Conclusions:
- PITX2 and PITX1 have overlapping functions in thyrotroph biology.
- PITX2 is involved in the thyrotroph response to hypothyroidism.
- The developed Tg(Tshb-Cre) mouse line is a valuable tool for studying gene function in thyrotrophs.
Related Concept Videos
Hypothyroidism II: Pathophysiology
Hypothyroidism is a disorder characterized by insufficient production of thyroid hormones, which regulate metabolism, energy balance, and multiple organ systems.TypesHypothyroidism is classified based on the level of dysfunction. Primary hypothyroidism results from intrinsic thyroid gland dysfunction, causing reduced hormone production despite normal or increased stimulation. Secondary hypothyroidism arises from inadequate thyroid-stimulating hormone (TSH) secretion by the pituitary. Tertiary...
Synthesis and Regulation of Thyroid Hormones
Low blood levels of the thyroid hormones — triiodothyronine (T3) and thyroxine (T4) — signal the hypothalamus to release the thyrotropin-releasing hormone (TRH). TRH then reaches the pituitary gland and stimulates the release of thyroid-stimulating hormone(TSH) into the bloodstream.
Upon reaching the thyroid gland, TSH stimulates the follicular cells' active uptake of iodide ions from the blood. The ions diffuse to the apical surface of the cells and are oxidized to iodine. The iodine is then...
Upon reaching the thyroid gland, TSH stimulates the follicular cells' active uptake of iodide ions from the blood. The ions diffuse to the apical surface of the cells and are oxidized to iodine. The iodine is then...
Hyperthyroidism II: Pathophysiology
Hyperthyroidism is a hypermetabolic state caused by elevated levels of thyroid hormones, triiodothyronine (T3) and thyroxine (T4). It results from dysregulation at the thyroid, pituitary, or immune system level and affects multiple organ systems.PathophysiologyThe most common cause of hyperthyroidism is Graves’ disease, an autoimmune disorder in which antibodies, specifically thyroid-stimulating antibodies (TSAb), a subtype of TSH receptor antibodies (TRAb), bind to and activate TSH receptors...
Functions of Thyroid Hormones
The thyroid hormone (TH) plays a pivotal role in the intricate orchestration of physiological processes, exerting profound effects on development, metabolism, and homeostasis throughout different life stages.
TH is indispensable for the normal development and maturation of the skeletal, muscular, and nervous systems during fetal and childhood growth. It facilitates bone mineral turnover and regulates protein synthesis in developing tissues, contributing significantly to overall growth and...
TH is indispensable for the normal development and maturation of the skeletal, muscular, and nervous systems during fetal and childhood growth. It facilitates bone mineral turnover and regulates protein synthesis in developing tissues, contributing significantly to overall growth and...
Major Hormones and Their Functions
Hormones, the biochemical messengers produced by endocrine glands, are pivotal in regulating bodily functions and maintaining homeostasis. Each hormone's balance is crucial; imbalances can lead to significant physiological disruptions. Major hormones include oxytocin, cortisol, epinephrine, estrogen, testosterone, thyroxine, growth hormone, insulin, and glucagon.
Oxytocin, produced in the hypothalamus and released by the pituitary gland, plays a role in social bonding, childbirth, and lactation.
Oxytocin, produced in the hypothalamus and released by the pituitary gland, plays a role in social bonding, childbirth, and lactation.
Hormones and Bone Tissue
The endocrine system produces and secretes hormones, which interact with the skeletal system. These hormones control bone growth, maintain bone once it is formed, and remodel it.
Hormones That Influence Osteoblasts and/or Maintain the Matrix
Several hormones are necessary for controlling bone growth and maintaining the bone matrix. The pituitary gland secretes growth hormone (GH), which, as its name implies, controls bone growth. This happens in several ways: first, it triggers chondrocyte...
Hormones That Influence Osteoblasts and/or Maintain the Matrix
Several hormones are necessary for controlling bone growth and maintaining the bone matrix. The pituitary gland secretes growth hormone (GH), which, as its name implies, controls bone growth. This happens in several ways: first, it triggers chondrocyte...
