The Pathogenic TSH β-Subunit Variant C105Vfs114X Causes a Modified Signaling Profile at TSHR

Abstract

(1) Background: Central congenital hypothyroidism (CCH) is a rare endocrine disorder that can be caused by mutations in the β-subunit of thyrotropin (TSHB). The TSHB mutation C105Vfs114X leads to isolated thyroid-stimulating-hormone-(TSH)-deficiency and results in a severe phenotype. The aim of this study was to gain more insight into the underlying molecular mechanism and the functional effects of this mutation based on two assumptions: a) the three-dimensional (3D) structure of TSH should be modified with the C105V substitution, and/or b) whether the C-terminal modifications lead to signaling differences. (2) Methods: wild-type (WT) and different mutants of hTSH were generated in human embryonic kidney 293 cells (HEK293 cells) and TSH preparations were used to stimulate thyrotropin receptor (TSHR) stably transfected into follicular thyroid cancer cells (FTC133-TSHR cells) and transiently transfected into HEK293 cells. Functional characterization was performed by determination of Gs, mitogen activated protein kinase (MAPK) and Gq/11 activation. (3) Results: The patient mutation C105Vfs114X and further designed TSH mutants diminished cyclic adenosine monophosphate (cAMP) signaling activity. Surprisingly, MAPK signaling for all mutants was comparable to WT, while none of the mutants induced PLC activation. (4) Conclusion: We characterized the patient mutation C105Vfs114X concerning different signaling pathways. We identified a strong decrease of cAMP signaling induction and speculate that this could, in combination with diverse signaling regarding the other pathways, accounting for the patient’s severe phenotype.

Cell and Molecular Biology of Thyroid Disorders 2.0

“…In this issue, Kalveram et al [ 10 ] published a research article about central CH, which is a rare and severe endocrine disorder. They demonstrated a mutation in the β-subunit of thyrotropin (thyroid-stimulating-hormone-B (TSH-B)).…”

“…In this Special Issue, a total of 12 excellent papers consisting of eight original articles [ 6 , 7 , 10 , 22 , 23 , 24 , 25 , 26 ], and four reviews [ 19 , 27 , 28 , 29 ] were published, as detailed in Table 1 .…”

“…This collection includes nine manuscripts focusing on TC [ 19 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ], two research articles on the topic of Graves’ disease [ 6 , 7 ], and one article with focus on central congenital hypothyroidism [ 10 ]. The TC studies published in this issue focused on prognostic, predictive markers or biomarkers [ 23 , 24 , 25 , 27 ], oncogenes [ 22 ] of TC, and anti-cancer drugs [ 19 , 26 , 28 , 29 ].…”

“…Kalveram et al [ 10 ] characterized in vitro the pathogenic TSH β-Subunit Variant C105Vfs114X for signalling pathway modifications. They showed that this mutation induces changes in the signalling profile at the TSHR.…”

“…Moreover, an animal study (mice) was used to the effects of FOXE1 gene dosage reduction on cancer phenotype in vivo [22]. Single cell culture studies [10,24], in vitro studies with cell-free systems using human, rat, mouse, and rabbit hepatic microsomes [26], combined in vitro and ex vivo studies (tumour samples) [25], and single in vivo clinical studies [6,7] were included in this issue. This Special Issue covered three studies investigating benign thyroid disorders.…”