H9c2 cardiomyoblasts produce thyroid hormone.
Thyroid hormone acts on a wide range of tissues. In the cardiovascular system, thyroid hormone is an important regulator of cardiac function and cardiovascular hemodynamics. Although some early reports in the literature suggested an unknown extrathyroidal source of thyroid hormone, it is currently thought to be produced exclusively in the thyroid gland, a highly specialized organ with the sole function of generating, storing, and secreting thyroid hormone. Whereas most of the proteins necessary for thyroid hormone synthesis are thought to be expressed exclusively in the thyroid gland, we now have found evidence that all of these proteins, i.e., thyroglobulin, DUOX1, DUOX2, the sodium-iodide symporter, pendrin, thyroid peroxidase, and thyroid-stimulating hormone receptor, are also expressed in cardiomyocytes. Furthermore, we found thyroglobulin to be transiently upregulated in an in vitro model of ischemia. When performing these experiments in the presence of 125 I, we found that 125 I was integrated into thyroglobulin and that under ischemia-like conditions the radioactive signal in thyroglobulin was reduced. Concomitantly we observed an increase of intracellularly produced, 125 I-labeled thyroid hormone. In conclusion, our findings demonstrate for the first time that cardiomyocytes produce thyroid hormone in a manner adapted to the cell's environment.
Meischl
Christof
C
VU University Medical Center, Department of Pathology, Amsterdam, The Netherlands. c.meischl@vumc.nl
Buermans
Henk P
HP
Hazes
Thierry
T
Zuidwijk
Marian J
MJ
Musters
René J P
RJ
Boer
Christa
C
van Lingen
Arthur
A
Simonides
Warner S
WS
Blankenstein
Marinus A
MA
Dupuy
Corrine
C
Paulus
Walter J
WJ
Hack
C Erik
CE
Ris-Stalpers
Carrie
C
Roos
Dirk
D
Niessen
Hans W M
HW
D000818:Animals; D018929:Cell Culture Techniques; D018076:DNA, Complementary / Q000235:genetics; D000074623:Dual Oxidases; D005420:Flavoproteins / Q000235:genetics; D007457:Iodine Radioisotopes / Q000378:metabolism; D008297:Male; D032383:Myocytes, Cardiac / Q000166:cytology / Q000502:physiology*; D019255:NADPH Oxidases / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification; D051381:Rats; D017208:Rats, Wistar; D013954:Thyroglobulin / Q000235:genetics; D013963:Thyroid Hormones / Q000096:biosynthesis
D018076:DNA, Complementary; D005420:Flavoproteins; D007457:Iodine Radioisotopes; D012333:RNA, Messenger; D013963:Thyroid Hormones; D013954:Thyroglobulin; D000074623:Dual Oxidases; D019255:NADPH Oxidases; C524752:Duox1 protein, rat; C486611:Duox2 protein, rat