Loss of thyroid hormone receptor activity in primary cultured rat hepatocytes is reversed by 2-mercaptoethanol.
In primary cultures of rat hepatocytes, specific thyroid-hormone-binding activity diminished with time and was hardly detectable at 24 h. In accordance with the loss of 3,5,3'-tri-iodothyronine (T3) binding, responses to the hormone disappeared, as indicated by low induction of the thyroid-hormone-responsive gene S14. In contrast, thyroid hormone receptor proteins were present, as determined by immunostaining with a specific antibody against the receptor. Thus the loss of T3 binding was due to receptor inactivation. After various attempts to restore the T3-binding activity, we found that 2-mercaptoethanol, a reducing agent, when added to the culture medium restored the hormone binding activity in a dose- and time-dependent manner. The observed kinetics and experiments using cycloheximide suggested that mercaptoethanol prevented inactivation of the newly synthesized receptors. Oxidoreductive conditions within cells may have a role in determining the level of activity of thyroid hormone receptors.
Yamamoto
N
N
Department of Biochemistry, Osaka City University Medical School, Japan.
Inoue
A
A
Takahashi
K P
KP
Li
Q L
QL
Nakamura
H
H
Tagami
T
T
Sasaki
S
S
Imura
H
H
Morisawa
S
S
D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D004229:Dithiothreitol / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008623:Mercaptoethanol / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011988:Receptors, Thyroid Hormone / Q000187:drug effects / Q000378:metabolism*; D014284:Triiodothyronine / Q000378:metabolism / Q000494:pharmacology
D012333:RNA, Messenger; D011988:Receptors, Thyroid Hormone; D014284:Triiodothyronine; D008623:Mercaptoethanol; D003513:Cycloheximide; D004229:Dithiothreitol