Related Experiment Video
Updated: Sep 27, 2026

High Efficiency Differentiation of Human Pluripotent Stem Cells to Cardiomyocytes and Characterization by Flow Cytometry
Published on: September 23, 2014
Triiodothyronine-mediated myosin heavy chain gene transcription in the heart
Sara Danzi1, Kaie Ojamaa, Irwin Klein
1Division of Endocrinology and Department of Medicine, North Shore University Hospital/New York University School of Medicine, Manhasset 11030, USA.
Abstract:
We developed an RT-PCR assay to study both the time course and the mechanism for the triiodothyronine (T(3))-induced transcription of the alpha- and beta-myosin heavy chain (MHC) genes in vivo on the basis of the quantity of specific heterogeneous nuclear RNA (hnRNA). The temporal relationship of changes in transcriptional activity to the amount of alpha-MHC mRNA and the coordinated regulation of transcription of more than one gene in response to T(3) are demonstrated here for the first time. Quantitation of alpha-MHC hnRNA demonstrated that T(3) induced alpha-MHC transcription in hypothyroid rats within 30 min of a single injection of T(3) (0.5 microg/100 g body wt). Maximal transcription rates (135% +/- 15.8 of euthyroid values) occurred 6 h after injection and subsequently declined in parallel with serum T(3) levels. The transcription of beta-MHC was reduced to 86% of peak hypothyroid levels 6 h after a single T(3) injection and reached a nadir of 59% of hypothyroid levels at 36 h. Analysis of the time course of T(3)-mediated induction of alpha-MHC hnRNA and repression of beta-MHC hnRNA indicates that separate molecular mechanisms are involved in the coordinated regulation of these genes.
Related Concept Videos
Master Transcription Regulators
Master Transcription Regulators
Cardiomyopathy III: Hypertrophic Cardiomyopathy
General Transcription Factors
Regulation of Heart Rates
The SNS increases heart rate through the release of norepinephrine and epinephrine, which act on beta-1 adrenergic receptors in the heart. This action increases the rate of depolarization in the sinoatrial (SA) node, the heart's...
Mechanism of Cardiac Arrhythmias

