TSHR signaling promotes hippocampal dependent memory formation through modulating Wnt5a/β-catenin mediated neurogenesis

Subclinical hyperthyroidism is defined biochemically as a low or undetectable thyroid-stimulating hormone (TSH) with normal thyroid hormone levels. Low TSHR signaling is considered to associate with cognitive impairment. However, the underlying molecular mechanism by which TSHR signaling modulates memory is poorly understood. In this study, we found that Tshr-deficient in the hippocampal neurons impairs the learning and memory abilities of mice, accompanying by a decline in the number of newborn neurons. Notably, Tshr ablation in the hippocampus decreases the expression of Wnt5a, thereby inactivating the β-catenin signaling pathway to reduce the neurogenesis. Conversely, activating of the Wnt/β-catenin pathway by the agonist SKL2001 results in an increase in hippocampal neurogenesis, resulting in the amelioration in the deficits of memory caused by Tshr deletion. Understanding how TSHR signaling in the hippocampus regulates memory provides insights into subclinical hyperthyroidism affecting cognitive function and will suggest ways to rationally design interventions for neurocognitive disorders.

Long noncoding RNA PVT1 modulates thyroid cancer cell proliferation by recruiting EZH2 and regulating thyroid-stimulating hormone receptor (TSHR)

The purposes of this study were to investigate the potential roles of long noncoding RNA (lncRNA) PVT1 in thyroid cancer cell proliferation and to explore their possible mechanisms. A total of 84 patients who were diagnosed as having thyroid cancer (papillary thyroid carcinoma (PTC), follicular thyroid carcinoma (FTC), and anaplastic thyroid carcinoma (ATC)) in Renji Hospital were enrolled in this study. Expressions of lncRNA PVT1 in thyroid cancer tissues and cell lines (IHH-4, FTC-133, and 8505C) were analyzed using RT-polymerase chain reaction (PCR) and western blotting analysis. The effects of lncRNA PVT1 expression on thyroid cancer cell proliferation and cell cycle were analyzed using flow cytometry. Furthermore, the effects of lncRNA expression on thyroid-stimulating hormone receptor (TSHR) expression and polycomb enhancer of zeste homolog 2 (EZH2) were also analyzed using RNA immunoprecipitation (RIP) assay and chromatin immunoprecipitation (ChIP) assay, respectively. Compared to the controls, lncRNA PVT1 was significantly up-regulated in thyroid tissues, as well as in three kinds of tumor cell lines (P < 0.05). Silenced PVT1 significantly inhibited thyroid cell line IHH-4, FTC-133, and 8505C cell proliferation and arrested cell cycle at G0/G1 stage and significantly decreased cyclin D1 and TSHR expressions (P < 0.05). Moreover, lncRNA PVT1 could be enriched by EZH2, and silencing PVT1 resulted in the decreased recruitment of EZH2. This study suggested that lncRNA PVT1 may contribute to tumorigenesis of thyroid cancer through recruiting EZH2 and regulating TSHR expression.