c-Fos downregulation positively regulates EphA5 expression in a congenital hypothyroidism rat model

CaMKIV mediates spine growth deficiency of hippocampal neurons by regulation of EGR3/BDNF signal axis in congenital hypothyroidism

Congenital hypothyroidism (CH) will cause cognitive impairment in the condition of delayed treatment. The hippocampus is one of the most affected tissues by CH, in which the functional structures of hippocampal neurons manifest deficiency due to aberrant expression of effector molecules. The Ca²⁺/Calmodulin-dependent protein kinase, CaMKIV, is downregulated in the hippocampal neurons, influencing the growth of dendritic spines in response to CH. However, the underlying mechanism is not fully elucidated. In the present study, the early growth response factor 3 (EGR3) was regulated by CaMKIV in the hippocampal neurons of CH rat pups, as was analyzed by transcriptome sequencing and in vitro cell experiments. EGR3 localized within hippocampal neurons in CA1, CA3, and dentate gyrus regions. Deficient EGR3 in the primary hippocampal neurons significantly reduced the density of dendritic spines by downregulating the expression of BDNF, and such effects could be rescued by supplementing recombinant BDNF protein. Taken together, CH mediates cognitive impairment of pups through the inactivation of CaMKIV in the hippocampal neurons, which decreases the expression of EGR3 and further reduces the production of BDNF, thereby impairing the growth of dendritic spines. Identifying CaMKIV/EGR3/BDNF pathway in the hippocampal neurons in the context of CH will benefit the drug development of intellectual disability caused by CH.

Transcription factors and regulators pathway-focused genes expression analysis in patients with different forms of thyroid pathology

BACKGROUND

Autoimmune thyroiditis (AIT) is a T cell-mediated organ-specific disorder and transcription factors have a critical role in the regulation of immune responses, especially in the fate of T-helper cells.

OBJECTIVE

This study aims to investigate changes in the gene expression profile of transcription factors and regulators in patients with different forms of thyroid pathology Methods. We used the pathway-specific real-time PCR array (Neurotrophins and Receptors RT2 Profiler PCR Array, QIAGEN, Germany) to identify and verify transcription factors and regulators pathway-focused genes expression in peripheral white blood cells of patients with postoperative hypothyroidism, hypothyroidism as a result of AIT and AIT with elevated serum an anti-thyroglobulin (anti-Tg) and anti-thyroid peroxidase (anti-TPO) antibodies.

RESULTS

It was shown that in patients with postoperative hypothyroidism FOS, NR1I2, STAT4, and TP53 significantly increased their expression whereas the expression of STAT1, STAT2, and STAT3 decreased. In patients with hypothyroidism as a result of AIT, we have found increased expression of NR1I2, STAT2, and STAT3. In contrast, the expression of STAT1 and TP53 decreased. FOS and STAT4 mRNAs did not change their expression. In patients with AIT and elevated serum anti-Tg and anti-TPO antibodies, the expression of FOS and NR1I2 reduced whereas the mRNA level of STAT3 increased. STAT1, STAT2, and STAT4 mRNAs did not change their expression. MYC did not change its expression in all groups of patients.

CONCLUSIONS

The results of this study demonstrate that autoimmune thyroiditis and hypothyroidism affect the mRNA-level expression of transcription factors and regulators genes in a gene-specific manner and that these changes to genes expression can be among the triggers of autoimmune inflammation progression in the thyroid gland.

Congenital hypothyroidism impairs spine growth of dentate granule cells by downregulation of CaMKIV

Congenital hypothyroidism (CH), a common neonatal endocrine disorder, can result in cognitive deficits if delay in diagnose and treatment. Dentate gyrus (DG) is the severely affected subregion of the hippocampus by the CH, where the dentate granule cells (DGCs) reside in. However, how CH impairs the cognitive function via affecting DGCs and the underlying mechanisms are not fully elucidated. In the present study, the CH model of rat pups was successfully established, and the aberrant dendrite growth of the DGCs and the impaired cognitive behaviors were observed in the offspring. Transcriptome analysis of hippocampal tissues following rat CH successfully identified that calcium/calmodulin-dependent protein kinase IV (CaMKIV) was the prominent regulator involved in mediating deficient growth of DGC dendrites. CaMKIV was shown to be dynamically regulated in the DG subregion of the rats following drug-induced CH. Interference of CaMKIV expression in the primary DGCs significantly reduced the spine density of dendrites, while addition of T3 to the primary DGCs isolated from CH pups could facilitate the spine growth of dendrites. Insights into relevant mechanisms revealed that CH-mediated CaMKIV deficiency resulted in the significant decrease of phosphorylated CREB in DGCs, in association with the abnormality of dendrites. Our results have provided a distinct cell type in hippocampus that is affected by CH, which would be beneficial for the treatment of CH-induced cognitive deficiency.