Impairment of the Hypothalamus-Pituitary-Thyroid Axis Caused by Naturally Occurring Mutations In Vitro.

The transcription factor GATA2 regulates gene expression in several cells and tissues, including hematopoietic tissues and the central nervous system. Recent studies revealed that loss-of-function mutations in are associated with hematological disorders. Our earlier in vitro studies showed that GATA2 plays an essential role in the hypothalamus-pituitary-thyroid axis (HPT axis) by regulating the genes encoding prepro-thyrotropin-releasing hormone (preproTRH) and thyroid-stimulating hormone β (TSHβ). However, the effect of GATA2 mutants on the transcriptional activity of their promoters remains unelucidated. In this study, we created five human mutations (, , , , and ) that were reported to be associated with hematological disorders and analyzed their functional properties, including transactivation potential and DNA-binding capacity toward the and the promoters. Three mutations (, , and ) within the C-terminal zinc-finger domain reduced the basal GATA2 transcriptional activity on both the and the promoters with a significant loss of DNA binding affinity. Interestingly, only the mutation reduced the GATA2 protein expression. Subsequent analysis demonstrated that the mutation possibly facilitated the GATA2 degradation process. R308P and S447R mutants exhibited decreased transcriptional activity under protein kinase C compared to the wild-type protein. In conclusion, we demonstrated that naturally occurring mutations impair the HPT axis through differential functional mechanisms in vitro.