ScRNAseq analysis of chicken embryonic pituitary reveals cell heterogeneity and a cell type co-expressing Gh and Pomc

Gene expression profiles and the heterogeneity among hormone-producing pituitary cells remain poorly characterized in most vertebrates, especially in chicken embryos. Using single-cell RNA sequencing, the transcriptomes of 4,346 basal and 10,835 corticosterone (CORT)-treated embryonic day 11 chicken pituitary cells were sequenced. Classical endocrine cell clusters were identified, and some were shown to express previously unreported marker genes. A cluster of uncommitted cells was identified that expressed markers for multiple endocrine cell types, with ~30% co-expressing Gh and Pomc mRNA. We named this population of cells the cortico-somatotrophs. The existence of cortico-somatotrophs were confirmed at both the mRNA and protein level. We further characterized the cortico-somatotrophs by utilizing the known effect of CORT to increase somatotroph abundance. Identification of cortico-somatotrophs challenges the prevailing view that corticotrophs and somatotrophs develop from distinct cell lineages. Overall design: Embryonic day 11 chicken pituitary cells were collected and dispersed, then treated with or without corticosterone (CORT). Through scRNAseq, different hormone-producing cell types were identified and characterized.