Thyroid hormone receptor beta and NCOA4 regulate terminal erythrocyte differentiation

Area of Science:

• Hematology
• Endocrinology
• Molecular Biology

Background:

• The role of thyroid hormone (TH) in erythropoiesis is long-established, but its precise molecular mechanisms remain unclear.
• Understanding TH's function in red blood cell production is vital for addressing anemia.

Purpose of the Study:

• To elucidate the molecular mechanisms by which thyroid hormone regulates terminal human erythroid cell differentiation.
• To identify key cofactors involved in TH-mediated erythropoiesis.

Main Methods:

• Depletion of TH from culture media to assess its impact on erythroid differentiation and enucleation.
• In vivo studies using TRβ agonists in an anemia mouse model.
• RNA-sequencing (RNA-seq) in human reticulocytes to identify cooperating factors.
• Genome-wide analysis of TH-induced NCOA4 recruitment to chromatin.

Main Results:

• Thyroid hormone is essential for terminal human erythroid differentiation and enucleation; its absence completely halts these processes.
• TRβ agonists promote erythroblast differentiation and improve anemia symptoms in mice by modulating erythroid gene expression.
• Nuclear receptor coactivator 4 (NCOA4) was identified as a critical regulator cooperating with TRβ in terminal differentiation.
• Ncoa4-deficient mice exhibit perinatal anemia and impaired erythropoiesis response to TH, with TH promoting NCOA4 recruitment to specific chromatin regions.

Conclusions:

• Thyroid hormone directly regulates terminal erythroid differentiation and enucleation through mechanisms involving NCOA4.
• The identified molecular pathway provides insights into red blood cell formation and suggests potential therapeutic targets for anemia treatment.