Apoptosis

, Volume 12, Issue 10, pp 1781–1794

Inhibition of apoptotic potency by ligand stimulated thyroid hormone receptors located in mitochondria

  • Nuttawut Saelim
  • Deborah Holstein
  • Estrella S. Chocron
  • Patricia Camacho
  • James Donald Lechleiter
Original Paper

DOI: 10.1007/s10495-007-0109-1

Cite this article as:
Saelim, N., Holstein, D., Chocron, E.S. et al. Apoptosis (2007) 12: 1781. doi:10.1007/s10495-007-0109-1

Abstract

We recently reported that shortened thyroid hormone receptor isoforms (TRs) can target mitochondria and acutely modulate inositol 1,4,5 trisphosphate (IP3)-mediated Ca2+ signaling when activated by thyroid hormone 3,5,3′-tri-iodothyronine (T3). Stimulation occurs via an increase in mitochondrial metabolism that is independent of transcriptional activity. Here, we present evidence that T3-bound xTRβA1s inhibit apoptotic activity mediated by cytochrome c release. An assay for apoptotic potency was modified to measure the ability of Xenopus oocyte extracts to induce morphological changes in isolated liver nuclei. Apoptotic potency was significantly decreased when oocyte extract was prepared from xTRβA1 expressing oocytes and treated with T3. The ability of T3 treatment to inhibit apoptosis was dependent on the expression of xTRβA1s in the mitochondrial fraction, not in the cytosolic fraction. T3 treatment also increased the membrane potential of isolated mitochondria prepared from oocytes expressing xTRβA1s but not from wildtype controls. We conclude that T3 acutely regulates cytochrome c release in a potential dependent manner by activating TRs located within mitochondria.

Keywords

Steroid receptorsApoptosis assayConfocal microscopyXenopus oocytes

Abbreviations

Ca2+

Calcium

IP3

Inositol 1,4,5-trisphosphate

T3

3,5,3′-tri-iodothyronine

TRs

Thyroid receptors

MBS

Modified barth’s solution

ΔΨ

Mitochondrial membrane potential

DEPC

Diethyl pyrocarbonate

Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • Nuttawut Saelim
    • 1
    • 3
  • Deborah Holstein
    • 1
  • Estrella S. Chocron
    • 1
  • Patricia Camacho
    • 2
  • James Donald Lechleiter
    • 1
  1. 1.Department of Cellular and Structural BiologyUniversity of Texas Health Science Center at San AntonioSan AntonioUSA
  2. 2.Department of PhysiologyUniversity of Texas Health Science Center at San AntonioSan AntonioUSA
  3. 3.Department of Pharmacy Practice, Faculty of Pharmaceutical SciencesNaresuan UniversityPitsanulokThailand