scholarly journals The Thyrotropin-Releasing Hormone Gene Is Regulated by Thyroid Hormone at the Level of Transcription in Vivo

Endocrinology ◽  
2010 ◽  
Vol 151 (2) ◽  
pp. 793-801 ◽  
Author(s):  
Michelle L. Sugrue ◽  
Kristen R. Vella ◽  
Crystal Morales ◽  
Marisol E. Lopez ◽  
Anthony N. Hollenberg
Keyword(s):  
Thyroid Hormone ◽  
Genomic Region ◽  
Model System ◽  
Model Systems ◽  
In Vivo Model ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Normal Production

The expression of the TRH gene in the paraventricular nucleus (PVH) of the hypothalamus is required for the normal production of thyroid hormone (TH) in rodents and humans. In addition, the regulation of TRH mRNA expression by TH, specifically in the PVH, ensures tight control of the set point of the hypothalamic-pituitary-thyroid axis. Although many studies have assumed that the regulation of TRH expression by TH is at the level of transcription, there is little data available to demonstrate this. We used two in vivo model systems to show this. In the first model system, we developed an in situ hybridization (ISH) assay directed against TRH heteronuclear RNA to measure TRH transcription directly in vivo. We show that in the euthyroid state, TRH transcription is present both in the PVH and anterior/lateral hypothalamus. In the hypothyroid state, transcription is activated in the PVH only and can be shut off within 5 h by TH. In the second model system, we employed transgenic mice that express the Cre recombinase under the control of the genomic region containing the TRH gene. Remarkably, TH regulates Cre expression in these mice in the PVH only. Taken together, these data affirm that TH regulates TRH at the level of transcription in the PVH only and that genomic elements surrounding the TRH gene mediate its regulation by T3. Thus, it should be possible to identify the elements within the TRH locus that mediate its regulation by T3 using in vivo approaches.

scholarly journals The TRH Gene Is Regulated by Thyroid Hormone at the Level of Transcription in Vivo

2010 ◽  
Vol 31 (1) ◽  
pp. 136-136
Author(s):  
Michelle L. Sugrue ◽  
Kristen R. Vella ◽  
Crystal Morales ◽  
Marisol E. Lopez ◽  
Anthony N. Hollenberg
Keyword(s):  
Thyroid Hormone ◽  
Genomic Region ◽  
Model System ◽  
Model Systems ◽  
In Vivo Model ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Normal Production

ABSTRACT The expression of the TRH gene in the paraventricular nucleus (PVH) of the hypothalamus is required for the normal production of thyroid hormone (TH) in rodents and humans. In addition, the regulation of TRH mRNA expression by TH, specifically in the PVH, ensures tight control of the set point of the hypothalamic-pituitary-thyroid axis. Although many studies have assumed that the regulation of TRH expression by TH is at the level of transcription, there is little data available to demonstrate this. We used two in vivo model systems to show this. In the first model system, we developed an in situ hybridization (ISH) assay directed against TRH heteronuclear RNA to measure TRH transcription directly in vivo. We show that in the euthyroid state, TRH transcription is present both in the PVH and anterior/lateral hypothalamus. In the hypothyroid state, transcription is activated in the PVH only and can be shut off within 5 h by TH. In the second model system, we employed transgenic mice that express the Cre recombinase under the control of the genomic region containing the TRH gene. Remarkably, TH regulates Cre expression in these mice in the PVH only. Taken together, these data affirm that TH regulates TRH at the level of transcription in the PVH only and that genomic elements surrounding the TRH gene mediate its regulation by T3. Thus, it should be possible to identify the elements within the TRH locus that mediate its regulation by T3 using in vivo approaches.

scholarly journals TMOD-12. THE ROLE OF INTEGRIN α V AND CD44 IN GBM MIGRATION USING HUMAN ORGANOTYPIC SLICES

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi265-vi265
Author(s):  
Zev Binder ◽  
Sarah Hyun Ji Kim ◽  
Pei-Hsun Wu ◽  
Anjil Giri ◽  
Gary Gallia ◽  
...  
Keyword(s):  
Human Brain ◽  
Cell Motility ◽  
Brain Tissue ◽  
Brain Slices ◽  
Model System ◽  
Model Systems ◽  
In Vivo Model ◽  
Human Brain Tissue

Abstract Current model systems used for GBM research include traditional in vitro cell line-based assays and in vivo animal studies. In vitro model systems offer the advantages of being easy to use, relatively inexpensive, and fast growing. However, these models lack key elements of the pathology they are attempting to model, including the biochemical and biophysical microenvironment and three-dimensional structure inherent to human brain tissue. In vivo model systems address these limitations, but have restrictions of their own. Species differences may result in non-applicable results and animal experiments are often not designed like clinical trials. Evidence of the limitations of current GBM models is found in the disparity between basic research findings and successful new treatments for GBMs in the clinic. Here we present an alternative model system for the study of human GBM cell motility and invasion, which features advantages of both in vitro and in vivo model systems. Using human organotypic brain slices as scaffolding for tumor growth, we explored the dynamic process of GBM cell invasion within human brain tissue. To demonstrate the utility of the model system, we investigated the effects of depletion of integrin α V (ITGAV) and CD44 on GBM cell motility. These two cell-surface proteins have been identified to have key functions in GBM cell motility. However, knockdown of ITGAV had little effect on tumor cell motility in organotypics while CD44 knockdown significantly reduced cell movement. Finally, we compare motility results from cells in human brain slices to those from cells growing on standard Matrigel and in mouse brain organotypics. We found significant differences in motility depending on the substrate in which the cells were moving. Our findings highlight the physiologic characteristics of human brain organotypics and demonstrate the use of real-time imaging in the ex vivo system.

scholarly journals A novel terpenoid class for prevention and treatment of KRAS ‐driven cancers: Comprehensive analysis using in situ, in vitro, and in vivo model systems

2020 ◽  
Vol 59 (8) ◽  
pp. 886-896
Author(s):  
Arsheed A. Ganaie ◽  
Hifzur R. Siddique ◽  
Ishfaq A. Sheikh ◽  
Aijaz Parray ◽  
Lei Wang ◽  
...  
Keyword(s):  
Comprehensive Analysis ◽  
Model Systems ◽  
In Vivo Model ◽  
Prevention And Treatment

scholarly journals In Vivo Interaction of Steroid Receptor Coactivator (SRC)-1 and the Activation Function-2 Domain of the Thyroid Hormone Receptor (TR) β in TRβ E457A Knock-In and SRC-1 Knockout mice

Endocrinology ◽  
2009 ◽  
Vol 150 (8) ◽  
pp. 3927-3934 ◽  
Author(s):  
Manuela Alonso ◽  
Charles Goodwin ◽  
XiaoHui Liao ◽  
Tania Ortiga-Carvalho ◽  
Danielle S. Machado ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormone Receptor ◽  
Steroid Receptor ◽  
Activation Function ◽  
Steroid Receptor Coactivator ◽  
Pituitary Thyroid Axis ◽  
Serum T4 ◽  
Thyroid Axis

The activation function-2 (AF-2) domain of the thyroid hormone (TH) receptor (TR)-β is a TH-dependent binding site for nuclear coactivators (NCoA), which modulate TH-dependent gene transcription. In contrast, the putative AF-1 domain is a TH-independent region interacting with NCoA. We determined the specificity of the AF-2 domain and NCoA interaction by evaluating thyroid function in mice with combined disruption of the AF-2 domain in TRβ, due to a point mutation (E457A), and deletion of one of the NCoAs, steroid receptor coactivator (SRC)-1. The E457A mutation was chosen because it abolishes NCoA recruitment in vitro while preserving normal TH binding and corepressor interactions resulting in resistance to TH. At baseline, disruption of SRC-1 in the homozygous knock-in (TRβE457A/E457A) mice worsened the degree of resistance to TH, resulting in increased serum T4 and TSH. During TH deprivation, disruption of AF-2 and SRC-1 resulted in a TSH rise 50% of what was seen when AF-2 alone was removed, suggesting that SRC-1 was interacting outside of the AF-2 domain. Therefore, 1) during TH deprivation, SRC-1 is necessary for activating the hypothalamic-pituitary-thyroid axis; 2) ligand-dependent repression of TSH requires an intact AF-2; and 3) SRC-1 may interact with the another region of the TRβ or the TRα to regulate TH action in the pituitary. This report demonstrates the dual interaction of NCoA in vivo: the TH-independent up-regulation possibly through another domain and TH-dependent down-regulation through the AF-2 domain.

scholarly journals Dual Functions of the Steroid Hormone Receptor Coactivator 3 in Modulating Resistance to Thyroid Hormone

2005 ◽  
Vol 25 (17) ◽  
pp. 7687-7695 ◽  
Author(s):  
Hao Ying ◽  
Fumihiko Furuya ◽  
Mark C. Willingham ◽  
Jianming Xu ◽  
Bert W. O'Malley ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Hormone Receptor ◽  
Thyroid Hormone Receptor ◽  
Steroid Hormone ◽  
Serum Insulin ◽  
Steroid Hormone Receptor ◽  
Resistance To Thyroid Hormone ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis

ABSTRACT Mutations of the thyroid hormone receptor β (TRβ) gene cause resistance to thyroid hormone (RTH). RTH is characterized by increased serum thyroid hormone associated with nonsuppressible thyroid-stimulating hormone (TSH) and impaired growth. It is unclear how the actions of TRβ mutants are modulated in vivo to affect the manifestation of RTH. Using a mouse model of RTH that harbors a knockin mutation of the TRβ gene (TRβPV mouse), we investigated the effect of the steroid hormone receptor coactivator 3 (SRC-3) on RTH. In TRβPV mice deficient in SRC-3, dysfunction of the pituitary-thyroid axis and hypercholesterolemia was lessened, but growth impairment of RTH was worsened. The lessened dysfunction of the pituitary-thyroid axis was attributed to a significant decrease in growth of the thyroid and pituitary. Serum insulin-like growth factor 1 (IGF-1) was further reduced in TRβPV mice deficient in SRC-3. This effect led to reduced signaling of the IGF-1/phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway that is known to mediate cell growth and proliferation. Thus, SRC-3 modulates RTH by at least two mechanisms, one via its role as a receptor coregulator and the other via its growth regulatory role through the IGF-1/PI3K/AKT/mTOR signaling.

The in vivo Orthodontic Banding Model for Vital Teeth and the in situ Orthodontic Banding Model for Hard-tissue Slabs

1992 ◽  
Vol 71 (3_suppl) ◽  
pp. 832-835 ◽  
Author(s):  
B. Øgaard ◽  
G. Rølla
Keyword(s):  
Root Surface ◽  
Model Systems ◽  
In Vivo Model ◽  
White Spot Lesions ◽  
Lesion Development ◽  
Special Diet ◽  
Mineralized Tissues ◽  
Removable Appliance

This paper presents the orthodontic banding model for vital teeth and the orthodontic in situ model for slabs of enamel, root surface, dentin, or other mineralized tissues such as shark enamel. The model for vital teeth is an in vivo model, since a crevice for plaque accumulation is created behind orthodontic bands on the buccal enamel surfaces of teeth in situ. Visible white-spot lesions are usually seen after a four-week banding period in the absence of fluoride. The microbiological flora developed behind the bands shows a similarity to that of natural caries. Microradiographic data show that the initial lesion is a softening of the enamel surface. Later, a subsurface lesion develops. A modification of the model has been developed for the use of slabs of mineralized tissues. In this model, slabs are mounted on a removable appliance. The slabs are covered with orthodontic banding material for plaque accumulation. Lesion development in enamel in the two model systems is almost identical. The benefit of the in vivo model is that caries development can be studied on vital teeth in young individuals. The model is independent of the patient's cooperation. No special diet is required, e.g., no sucrose rinsing. In the in situ model, slabs could be examined after one study period and then replaced for another period.

In Vitro and In Vivo Model Systems for the Study of Allergic and Inflammatory Disorders in Man

CHEST Journal ◽  
1985 ◽  
Vol 87 (5) ◽  
pp. 162S-164S ◽  
Author(s):  
Stephen P. Peters ◽  
Robert M. Naclerio ◽  
Alkis Togias ◽  
Robert P. Schleimer ◽  
Donald W. MacGlashan ◽  
...  
Keyword(s):  
Model Systems ◽  
In Vivo Model ◽  
Inflammatory Disorders

scholarly journals Neuropeptide Y1 and Y5 Receptors Mediate the Effects of Neuropeptide Y on the Hypothalamic-Pituitary-Thyroid Axis

Endocrinology ◽  
2002 ◽  
Vol 143 (12) ◽  
pp. 4513-4519 ◽  
Author(s):  
Csaba Fekete ◽  
Sumit Sarkar ◽  
William M. Rand ◽  
John W. Harney ◽  
Charles H. Emerson ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Food Intake ◽  
Neuropeptide Y ◽  
Paraventricular Nucleus ◽  
Receptor Agonist ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Ad Libitum ◽  
Thyroid Hormone Levels ◽  
Hpt Axis

Abstract Neuropeptide Y (NPY) is one of the most important hypothalamic-derived neuropeptides mediating the effects of leptin on energy homeostasis. Central administration of NPY not only markedly stimulates food intake, but simultaneously inhibits the hypothalamic-pituitary-thyroid axis (HPT axis), replicating the central hypothyroid state associated with fasting. To identify the specific NPY receptor subtypes involved in the action of NPY on the HPT axis, we studied the effects of the highly selective Y1 ([Phe7,Pro34]pNPY) and Y5 ([chicken pancreatic polypeptide1–7, NPY19–23, Ala31, Aib32 (aminoisobutyric acid), Q34]human pancreatic polypeptide) receptor agonists on circulating thyroid hormone levels and proTRH mRNA in hypophysiotropic neurons of the hypothalamic paraventricular nucleus. The peptides were administered continuously by osmotic minipump into the cerebrospinal fluid (CSF) over 3 d in ad libitum-fed animals and animals pair-fed to artificial CSF (aCSF)-infused controls. Both Y1 and Y5 receptor agonists nearly doubled food intake compared with that of control animals receiving aCSF, similar to the effect observed for NPY. NPY, Y1, and Y5 receptor agonist administration suppressed circulating levels of thyroid hormones (T3 and T4) and resulted in inappropriately normal or low TSH levels. These alterations were also associated with significant suppression of proTRH mRNA in the paraventricular nucleus, particularly in the Y1 receptor agonist-infused group [aCSF, NPY, Y1, and Y5 (density units ± sem), 97.2 ± 8.6, 39.6 ± 8.4, 19.9 ± 1.9, and 44.6 ± 8.4]. No significant differences in thyroid hormone levels, TSH, or proTRH mRNA were observed between the agonist-infused FSanimals eating ad libitum and the agonist-infused animals pair-fed with vehicle-treated controls. These data confirm the importance of both Y1 and Y5 receptors in the NPY-mediated increase in food consumption and demonstrate that both Y1 and Y5 receptors can mediate the inhibitory effects of NPY on the HPT axis.

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