Cited by 109Thyroid Disorders and TreatmentsUbiquitin and proteasome pathwaysGrowth Hormone and Insulin-like Growth Factors

Substrate-Induced Down-Regulation of Human Type 2 Deiodinase (hD2) Is Mediated through Proteasomal Degradation and Requires Interaction with the Enzyme’s Active Center1

Steinsapir, Jaime, Bianco, Antonio C., Buettner, Christoph, Harney, John, Larsen, P. Reed·2000·Endocrinology

Abstract

Type 2 iodothyronine deiodinase (D2) catalyzes the first step in thyroid hormone action, the deiodination of T4 to T3. Endogenous D2 activity is posttranslationally regulated by substrate that accelerates its degradation through the ubiquitin-proteasome pathway. To understand how D2 activity correlates with D2 protein during its normal decay and rT3-induced down-regulation, HEK-293 cells, transiently expressing human D2, were labeled with Na75SeO3 and then treated with 100 microM cycloheximide (CX), 30 nM rT3, and/or 10 microM MG132, a specific proteasome inhibitor, for 2-4 h. D2 protein and enzyme activity changed in parallel, disappearing with a half-life of 2 h in the presence of CX, or 1 h when CX + rT3 were combined. Treatment with MG132 blocked these effects. We created selenocysteine (Sec) 133 to cysteine (Cys) or alanine (Ala) D2 mutants, without changing Sec 266. The CysD2 activity and protein levels were also parallel, with a similar half-life of approximately 2 h, whereas the rT3-induced D2 down-regulation required approximately 1000-fold higher rT3 concentration (30 microM) due to a proportionally higher Michaelis constant of CysD2. In similar experiments, the AlaD2 mutant retained the short half-life but was not catalytically active and not susceptible to rT3-accelerated degradation. We conclude that substrate-induced loss of D2 activity is due to proteasomal degradation of the enzyme and requires interaction with the catalytic center of the protein.

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Crossref · 10.1210/endo.141.3.7355

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  • T4 and rT3 inhibit DIO2 by promoting its ubiquitination, which inhibits DIO2 activity and targets it for proteasomal degradation, forming an incoherent feedforward motif with T3 as the output.

    “T4 and rT3 also inhibit DIO2 by promoting its ubiquitination, which inhibits DIO2 activity and targets it for proteasomal degradation (37–40), forming an incoherent feedforward motif with T3 as the output.”

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Authors
Steinsapir, J., Bianco, A. C., Buettner, C., Harney, J., & Larsen, P. R.
Affiliations
Brigham and Women's Hospital (US)
Corresponding author
Larsen, P. Reed
Venue
Endocrinology
Published
2000-03
Volume
141
Issue
3
Pages
1127-1135
ISSN
  • 0013-7227 (ISSN-L)
  • 1945-7170
OpenAlex
W2119053116
Cited by
109
References
3
Citations by year
2024: 3 · 2023: 2 · 2022: 2 · 2021: 6 · 2020: 2 · 2019: 4 · 2018: 3 · 2017: 1 · 2016: 3 · 2015: 2 · 2014: 6 · 2013: 3 · 2012: 4
FWCI
5.24
Type
journal article
Language
en
Open access
closed
Locations
  • Endocrinology (publishedVersion)
  • PubMed (publishedVersion)
  • Rutgers University Community Repository (Rutgers University) (submittedVersion)
Funders
  • National Institutes of Health (NIH-R01)
  • National Institute of Diabetes and Digestive and Kidney Diseases (R01DK036256)
Topics
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Disorders and Treatments
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Ubiquitin and proteasome pathways
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Growth Hormone and Insulin-like Growth Factors
Keywords
type 2 deiodinase, reverse T3, proteasomal degradation, ubiquitin-proteasome system, selenocysteine, catalytic site, protein half-life, thyroid hormone action, enzyme activity
MeSH terms
Alanine, Amino Acid Sequence, Binding Sites, Cells, Cultured, Cycloheximide, Cysteine, Cysteine Endopeptidases, Humans, Indicators and Reagents, Iodide Peroxidase, Molecular Sequence Data, Multienzyme Complexes, Plasmids, Protein Synthesis Inhibitors, Selenium Radioisotopes, Thyroxine, Transfection, Triiodothyronine, Reverse, Down-Regulation, Mutagenesis, Proteasome Endopeptidase Complex

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