Abstract
TSH is an important physiological regulator of growth and function in thyroid gland. The mechanism of action of TSH depends on interaction with its receptor coupled to heterotrimeric G proteins. We show here that TSH induces the phosphorylation of tyrosine in the intracellular kinases Janus kinase 1 (JAK1) and -2 (JAK2) in rat thyroid cells and in Chinese hamster ovary (CHO) cells transfected with human TSH receptor (TSHR). The JAK family substrates STAT3 (signal transducers and activators of transcription) are rapidly tyrosine phosphorylated in response to TSH. We also find that JAK1, JAK2, and STAT3 coprecipitate with the TSHR, indicating that the TSHR may be able to signal through the intracellular phosphorylation pathway used by the JAK-STAT cascade. TSH increases STAT3-mediated promoter activity and also induces endogenous SOCS-1 (suppressor of cytokine signaling-1) gene expression, a known target gene of STAT3. The expression of a dominant negative form of STAT3 completely inhibited TSH-mediated SOCS-1 expression. These findings suggest that the TSHR is able to signal through JAK/STAT3 pathways.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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CHO Cells
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Carrier Proteins / biosynthesis
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Carrier Proteins / genetics
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Cells, Cultured
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Cricetinae
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Cricetulus
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism
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DNA-Binding Proteins / physiology*
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Genes, Dominant
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Humans
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Intracellular Signaling Peptides and Proteins*
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Janus Kinase 1
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Janus Kinase 2
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Macromolecular Substances
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Phosphorylation
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Protein Processing, Post-Translational
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Protein-Tyrosine Kinases / physiology*
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Proto-Oncogene Proteins*
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Rats
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Receptors, Thyrotropin / drug effects
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Receptors, Thyrotropin / metabolism
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Recombinant Fusion Proteins / physiology
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Repressor Proteins*
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STAT1 Transcription Factor
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STAT3 Transcription Factor
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Signal Transduction*
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Suppressor of Cytokine Signaling 1 Protein
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Suppressor of Cytokine Signaling Proteins
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Thyroid Gland / cytology
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Thyroid Gland / drug effects*
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Thyrotropin / pharmacology
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Thyrotropin / physiology*
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Trans-Activators / genetics
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Trans-Activators / metabolism
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Trans-Activators / physiology*
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Transcription, Genetic
Substances
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Carrier Proteins
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DNA-Binding Proteins
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Intracellular Signaling Peptides and Proteins
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Macromolecular Substances
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Proto-Oncogene Proteins
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Receptors, Thyrotropin
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Recombinant Fusion Proteins
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Repressor Proteins
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SOCS1 protein, human
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STAT1 Transcription Factor
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STAT1 protein, human
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STAT3 Transcription Factor
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STAT3 protein, human
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Socs1 protein, rat
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Stat3 protein, rat
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Suppressor of Cytokine Signaling 1 Protein
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Suppressor of Cytokine Signaling Proteins
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Trans-Activators
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Thyrotropin
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Protein-Tyrosine Kinases
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JAK1 protein, human
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JAK2 protein, human
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Jak1 protein, rat
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Jak2 protein, rat
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Janus Kinase 1
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Janus Kinase 2