Thyroid hormone effect on human mitochondria measured by flow cytometry

Abstract

Background: Mitochondrial function may be impaired in a number of diseases including metabolic syndrome, cardiovascular disease and endocrine disorders. Therefore it is important to be able to measure mitochondrial function in human cells. Purpose: The aim of the present study was to evaluate a method to measure mitochondrial function in human derived cells, which also would reflect regulation by thyroid hormones. Methods: The MDA-MB-231 cell line (a human breast cancer cell line) was incubated with bioactive iodothyronines (T₄, 3′-3, 5-T₃, 3, 5-T₂) 50nmol/l for 3 h. Mitochondrial membrane potentials (MMP) were measured by a flow cytometer after staining with Tetramethylrhodamine methyl ester (TMRM). Also, the effect of TRIAC (a stimulator of thyroid hormone nuclear receptors) and L-Carnitine (an inhibitor of thyroid hormone passage into the nucleus) was examined. Findings: It was possible to measure mitochondrial membrane potential (MMP) in human derived cells and to examine thyroid hormone effects using flow cytometry. Bioactive iodothyronines increased mitochondrial membrane potential. TRIAC had no effect and L-Carnitine only inhibited T₄ stimulation of membrane potential. Conclusion: Flow cytometry may be a valuable method for examining and testing mitochondrial function in human cells. Our findings demonstrate increase of mitochondrial membrane potential and an extra nuclear short time effect of 3, 5-T₂ on mitochondrial activity.

Key Words::

• Thyroid hormones
• flow cytometry
• TMRM fluorescence
• mitochondria

Acknowledgements

The authors would like to thank technicians Dorthe Toftdal, Gitte Melsen and Jette Ellehauge at the Department of Clinical Biochemistry, Næstved Hospital, Næstved, Denmark for their participation.

This study was supported by a grant from The Danish Agency for Science, Technology and Innovation 271-08-0020, Zealand Regional (Medical) Research Foundation and Zealand Region, Hospital South, Medical Research Foundation 26-2007. The authors want to thank Maria Kvetny, MA scientific linguistic consultant, Institute of Odontology, Faculty of Health Sciences, University of Copenhagen, for linguistic support.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.