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Expression of thyroid hormone receptor isoforms down-regulated by thyroid hormone in human medulloblastoma cells

Tsuyoshi Monden1, Yasuyo Nakajima, Tetsu Hashida

  • 1Department of Endocrinology and Metabolism, Dokkyo University School of Medicine, Tochigi, Japan.

Endocrine Journal
|April 19, 2006
PubMed

Insights

Thyroid hormone (T3) affects thyroid hormone receptor (TR) expression in medulloblastoma cells. T3 down-regulates TR mRNA levels, indicating post-transcriptional regulation at the RNA stability level.

Area of Science:

  • Neuro-oncology
  • Endocrinology
  • Molecular Biology

Background:

  • Thyroid hormone is crucial for central nervous system development, including the cerebellum.
  • The impact of thyroid hormone on cerebellar malignant tumors is not well understood.

Purpose of the Study:

  • To investigate thyroid hormone receptor (TR) isoform expression in human medulloblastoma cells.
  • To determine the effects of thyroid hormone (T3) on TR expression in these cells.

Main Methods:

  • Northern blot and RT-PCR were used to detect TR isoform mRNA expression in HTB-185 cells.
  • Cells were treated with T3, actinomycin D, and cycloheximide to assess TR mRNA regulation.

Main Results:

  • TRalpha2 mRNA was detected, while TRalpha1 and TRbeta1 were detected by RT-PCR, and TRbeta2 was not expressed.
  • T3 treatment decreased TRalpha1, TRalpha2, and TRbeta1 mRNA levels.
  • T3 influenced TR mRNA stability and required new protein synthesis for down-regulation.

Conclusions:

  • Thyroid hormone down-regulates TR expression in medulloblastoma cells.
  • TR expression is post-transcriptionally regulated by T3, primarily at the level of RNA stability.

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