Thyroidal expression of ER molecular chaperone GRP170 is required for efficient TSH-mediated thyroid hormone synthesis
Xiaohan Zhang, … , Teresa M. Buck, Peter Arvan
Xiaohan Zhang, … , Teresa M. Buck, Peter Arvan
Published September 9, 2025
Citation Information: JCI Insight. 2025;10(17):e191837. https://doi.org/10.1172/jci.insight.191837.
View: Text | PDF
Research Article Cell biology Endocrinology

Thyroidal expression of ER molecular chaperone GRP170 is required for efficient TSH-mediated thyroid hormone synthesis

Abstract

Intracellular trafficking of secretory and membrane proteins from the endoplasmic reticulum (ER) to the cell surface, via the secretory pathway, is crucial to the differentiated function of epithelial tissues. In the thyroid gland, a prerequisite for such trafficking is proper protein folding in the ER, assisted by an array of ER molecular chaperones. One of the most abundant of these chaperones, Glucose-Regulated-Protein-170 (GRP170, encoded by Hyou1), is a noncanonical hsp70-like family member. Thyroid follicular epithelial cells abundantly express GRP170, but the role of this abundant ER chaperone in thyrocytes remains unknown. Here, we have examined the effect of inducible Pax8-specific (thyroid and kidney) deficiency of GRP170 in mice, in parallel with siRNA-treated PCCL3 (rat) thyrocytes for knockdown of GRP170. Thyrocyte-specific loss of GRP170 in vivo triggers primary hypothyroidism with a deficient thyroidal response to Thyroid-Stimulating Hormone (TSH). In addition, knockdown of GRP170 in PCCL3 thyrocytes inhibits the folding and forward trafficking of TSH receptors to the cell surface. Taken together, our findings suggest that GRP170 contributes to the conformational maturation of TSH receptors and thyroid gland responsiveness to TSH, which is required for proper regulation of thyroid hormone synthesis.

Authors

Xiaohan Zhang, Crystal Young, Xiao-Hui Liao, Samuel Refetoff, Stephanie M. Mutchler, Jeffrey L. Brodsky, Teresa M. Buck, Peter Arvan

×

Figure 6

Phenotype of thyrocyte-specific deficiency of GRP170 in PCCL3 cells.

Options: View larger image (or click on image) Download as PowerPoint
Phenotype of thyrocyte-specific deficiency of GRP170 in PCCL3 cells. (A)...
(A) Immunoblotting of GRP170 and TG content of cells (last 6 lanes) and medium collected for 6 hours (first 6 lanes) at 48 hours after siRNA-mediated knockdown of GRP170, or scrambled oligo control. Actin is a loading control. (B) Quantitation of GRP170 protein levels and TG secretion from the indicated samples (n = 3 independent transfections in each group; data are shown as mean ± SD, t test, **P < 0.01). (C) Immunoblotting of NIS protein at 48 hours after siRNA-mediated knockdown of GRP170 (n = 3 transfections per group). Actin is a loading control. (D) Digestion of NIS protein with endoglycosidase H, or PNGase F in the samples as indicated (n = 4 transfections per group). (E) PCCL3 cells were transfected either with empty vector (–) or to express TSHR-GFP as indicated; after 24 hours, the cells were transfected with siRNA for knockdown of GRP170 or scrambled oligo control. At 48 hours after knockdown, the cells were lysed, digested with endoglycosidase H or PNGase F or were mock-digested, analyzed by 3%–8% Tris-Acetate NuPAGE, electrotransferred to nitrocellulose, and immunoblotted with anti-GFP antibodies. Endo H–sensitive forms are indicated with up-sloped red arrows; endo H–resistant forms are indicated with down-sloped green arrows. (F) Quantitation of the fraction of endo H–resistant TSHR-GFP from the indicated samples (n = 4 independent transfections in each group; data are shown as mean ± SD, t test, *P < 0.05). (G) Quantitation of surface-biotinylated TSHR-GFP in PCCL3 cells from the experiments shown in Supplemental Figure 4 (data are shown as mean ± SD, t test, *P < 0.05).