Multi-omic profiling of pituitary thyrotropic cells and progenitors

Abstract

Background The pituitary gland is a neuroendocrine organ containing diverse cell types specialized in secreting hormones that regulate physiology. Pituitary thyrotropes produce thyroid-stimulating hormone (TSH), a critical factor for growth and maintenance of metabolism. The transcription factors POU1F1 and GATA2 have been implicated in thyrotrope fate, but the transcriptomic and epigenomic landscapes of these neuroendocrine cells have not been characterized. The goal of this work was to discover transcriptional regulatory elements that drive thyrotrope fate. Results We identified the transcription factors and epigenomic changes in chromatin that are associated with differentiation of POU1F1-expressing progenitors into thyrotropes using cell lines that represent an undifferentiated Pou1f1 lineage progenitor (GHF-T1) and a committed thyrotrope line that produces TSH (TαT1). We compared RNA-seq, ATAC-seq, histone modification (H3K27Ac, H3K4Me1, and H3K27Me3), and POU1F1 binding in these cell lines. POU1F1 binding sites are commonly associated with bZIP transcription factor consensus binding sites in GHF-T1 cells and Helix-Turn-Helix (HTH) or basic Helix-Loop-Helix (bHLH) factors in TαT1 cells, suggesting that these classes of transcription factors may recruit or cooperate with POU1F1 binding at unique sites. We validated enhancer function of novel elements we mapped near Cga, Pitx1, Gata2, and Tshb by transfection in TαT1 cells. Finally, we confirmed that an enhancer element near Tshb can drive expression in thyrotropes of transgenic mice, and we demonstrate that GATA2 enhances Tshb expression through this element. Conclusion These results extend the ENCODE multi-omic profiling approach to the pituitary gland, which should be valuable for understanding pituitary development and disease pathogenesis. Graphical abstract

Duplications disrupt chromatin architecture and rewire GPR101-enhancer communication in X-linked acrogigantism

“…Those CREs were validated in an analogous experimental setting to ours. 57 Interestingly, about a quarter of human candidate silencer elements from one cell type can have dual activity and act as active enhancers in different cell types and chromatin contexts. 58 This raises the intriguing possibility that some of our candidate CREs displaying transcriptional silencing in GH3 and HEK293 could actually function as enhancers in the X-LAG-affected subjects' pituitary cells.…”

Transcriptomic Profiles of Normal Pituitary Cells and Pituitary Neuroendocrine Tumor Cells

“…In normal thyrotrophs, transcription factors GATA and PIT1 interact to drive TSHβ gene expression [34,35]. ScRNA-seq on human fetal pituitary shows that the transcription of GATA2 may involve two SoxC family genes, SOX4 and SOX11, which are expressed before GATA2 expression and bind to the regulatory region of GATA2 in thyrotroph precursor cells [14].…”

“…ScRNA-seq on human fetal pituitary shows that the transcription of GATA2 may involve two SoxC family genes, SOX4 and SOX11, which are expressed before GATA2 expression and bind to the regulatory region of GATA2 in thyrotroph precursor cells [14]. Bulk RNA-seq and ATAC-seq in thyrotroph cell cultures show high GATA2 expression in thyrotroph cells and a large area of accessible chromatin upstream of GATA2, respectively [35]. Pituitary-specific GATA2 knock-out mice show transient loss of thyrotroph cells and decreased production of TSH in response to hypothyroidism induction, in addition to compromised gonadotroph function [36].…”

Genetic overlap between schizophrenia and height implicates pituitary and immune response

“…In conclusion, our analyses point to a complex genetic interplay between SCZ and height, that converges on biological processes involving immune response and the pituitary, a gland tightly associated with immune functions 28 (see Figure 2A and B for a detailed overview). Among the prioritized genes, LIN28B is mainly expressed in the pituitary and testis, exhibits effects on growth and developmental timing 29,30 , and regulates the development of thyrotrope 31 , mesenchymal cells 32 and immune cells 33 . GIGYF2 and HLA-C can regulate immune response to pathogens [34][35][36] .…”