Regulation of thyroid hormone receptor isoforms in physiological and pathological cardiac hypertrophy

Koichiro Kinugawa, Katsunori Yonekura, Ralff C.J. Ribeiro, Yoko Eto, Teruhiko Aoyagi, John D. Baxter, S. Albert Camacho, Michael R. Bristow, Carlin S. Long, Paul C. Simpson

Research output: Contribution to journalArticlepeer-review

160 Scopus citations

Abstract

Physiological and pathological cardiac hypertrophy have directionally opposite changes in transcription of thyroid hormone (TH)-responsive genes, including α- and β-myosin heavy chain (MyHC) and sarcoplasmic reticulum Ca2+-ATPase (SERCA), and TH treatment can reverse molecular and functional abnormalities in pathological hypertrophy, such as pressure overload. These findings suggest relative hypothyroidism in pathological hypertrophy, but serum levels of TH are usually normal. We studied the regulation of TH receptors (TRs) β1, α1, and α2 in pathological and physiological rat cardiac hypertrophy models with hypothyroid- and hyperthyroid-like changes in the TH target genes, α- and β-MyHC and SERCA. All 3 TR subtypes in myocytes were downregulated in 2 hypertrophy models with a hypothyroid-like mRNA phenotype, phenylephrine in culture and pressure overload in vivo. Myocyte TRβ1 was upregulated in models with a hyperthyroid-like phenotype, TH (triiodothyronine, T3), in culture and exercise in vivo. In myocyte culture, TR overexpression, or excess T3, reversed the effects of phenylephrine on TH-responsive mRNAs and promoters. In addition, TR cotransfection and treatment with the TRβ1-selective agonist GC-1 suggested different functional coupling of the TR isoforms, TRβ1 to transcription of β-MyHC, SERCA, and TRβ1, and TRα1 to α-MyHC transcription and increased myocyte size. We conclude that TR isoforms have distinct regulation and function in rat cardiac myocytes. Changes in myocyte TR levels can explain in part the characteristic molecular phenotypes in physiological and pathological cardiac hypertrophy.

Original languageEnglish (US)
Pages (from-to)591-598
Number of pages8
JournalCirculation research
Volume89
Issue number7
DOIs
StatePublished - Sep 28 2001
Externally publishedYes

Keywords

  • Cardiac myocyte
  • Physiological and pathological hypertrophy
  • Rat
  • Thyroid hormone receptor
  • α-adrenergic receptor

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

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