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An Ex vivo Culture System to Study Thyroid Development
Published on: June 6, 2014
Expression and function of the homeodomain-containing protein Hex in thyroid cells
L Pellizzari1, A D'Elia, A Rustighi
1Dipartimento di Scienze e Tecnologie Biomediche, Università di Udine, Italy.
Nucleic Acids Research
|June 28, 2000
Summary
The homeodomain protein Hex is present in adult thyroid glands and represses thyroglobulin promoter activity, suggesting a role in thyroid cell differentiation. Its expression is reduced by TSH and abolished in cancer cells.
Area of Science:
- Molecular Biology
- Developmental Biology
- Endocrinology
Background:
- The homeodomain protein Hex (Prh) is involved in early development and its expression is lost during terminal differentiation.
- Hex is expressed during early thyroid development, but its role in adult thyroids and follicular cells is unknown.
Purpose of the Study:
- To investigate Hex expression and function in adult thyroid gland and follicular thyroid cells.
- To determine Hex's effect on the thyroglobulin promoter and its interaction with transcription factors.
Main Methods:
- Analysis of Hex mRNA in adult rat and human thyroid glands and differentiated cell lines.
- Co-transfection assays to assess Hex's effect on the thyroglobulin promoter.
- Protein-DNA interaction studies to identify Hex binding sites.
Main Results:
- Hex mRNA is present in adult thyroid glands and differentiated follicular cell lines.
- TSH reduces Hex expression in FRTL-5 cells; Hex is abolished in oncogene-transformed cells.
- Hex represses the thyroglobulin promoter, inhibiting TTF-1 and Pax8 activity.
- Hex binds to specific sites on the thyroglobulin promoter with relaxed DNA binding specificity.
Conclusions:
- Hex is present in adult thyroid tissue and plays a role in regulating thyroid cell differentiation.
- Hex acts as a repressor of the thyroglobulin promoter, influencing thyroid-specific gene expression.
- Hex's unique DNA binding properties may contribute to its function in thyroid cells.
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