Roles of hydrogen peroxide in thyroid physiology and disease.
BACKGROUND
The long-lived thyroid cell generates, for the synthesis of thyroid hormones, important amounts of H2O2 that are toxic in other cell types. This review analyzes the protection mechanisms of the cell and the pathological consequences of disorders of this system.


METHODS
The literature on H2O2 generation and disposal, thyroid hormone synthesis, and their control in the human thyroid is analyzed.


RESULTS
In humans, H2O2 production by dual-oxidases and consequently thyroid hormone synthesis by thyroperoxidase are controlled by the phospholipase C-Ca2+-diacylglycerol arm of TSH receptor action. H2O2 in various cell types, and presumably in thyroid cells, is a signal, a mitogen, a mutagen, a carcinogen, and a killer. The various protection mechanisms of the thyroid cell against H2O2 are analyzed. They include the separation of the generating enzymes (dual-oxidases), their coupling to thyroperoxidase in a proposed complex, the thyroxisome, and H2O2 degradation systems.


CONCLUSIONS
It is proposed that various pathologies can be explained, at least in part, by overproduction and lack of degradation of H2O2 (tumorigenesis, myxedematous cretinism, and thyroiditis) and by failure of the H2O2 generation or its positive control system (congenital hypothyroidism).
Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire (IRIBHM), School of Medicine, Université Libre de Bruxelles, Route de Lennik 808, 1070 Brussels, Belgium.
Y
Y
Song
N
N
Driessens
M
M
Costa
X
X
De Deken
V
V
Detours
B
B
Corvilain
C
C
Maenhaut
F
F
Miot
J
J
Van Sande
M-C
MC
Many
J E
JE
Dumont
D000818:Animals; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D013959:Thyroid Diseases / Q000378:metabolism* / Q000503:physiopathology*; D013961:Thyroid Gland / Q000502:physiology*
D006861:Hydrogen Peroxide