Single-cell transcriptomic analysis of adult mouse pituitary reveals sexual dimorphism and physiologic demand-induced cellular plasticity
Ontology highlight
ABSTRACT: The anterior pituitary gland drives a set of highly conserved physiologic processes in mammalian species. These hormonally controlled processes are central to somatic growth, pubertal transformation, fertility, lactation, and metabolism. Current models, largely based on candidate gene based immuno-histochemical and mRNA analyses, suggest that each of the seven hormones synthesized by the pituitary is produced by a specific and exclusive cell-lineage. However, emerging evidence suggests more complex relationship between hormone specificity and cell plasticity. Here we have applied massively parallel single-cell RNA sequencing (scRNA-seq), in conjunction with complementary imaging-based single-cell analyses of mRNAs and proteins, to systematically map both cell-type diversity and functional state heterogeneity in adult male and female mouse pituitaries at single-cell resolution and in the context of major physiologic demands. These quantitative single-cell analyses reveal sex-specific cell-type composition under normal pituitary homeostasis, identify an array of cells associated with complex complements of hormone-enrichment, and undercover non-hormone producing interstitial and supporting cell-types. Interestingly, we also identified a Pou1f1-expressing cell population that is characterized by a unique multi-hormone gene expression profile. In response to two well-defined physiologic stresses, dynamic shifts in cellular diversity and transcriptome profiles were observed for major hormone producing and the putative multi-hormone cells. These studies reveal unanticipated cellular complexity and plasticity in adult pituitary, and provide a rich resource for further validating and expanding our molecular understanding of pituitary gene expression programs and hormone production.
Project description:Understanding of physiology and pathology of an organ composed of variety of cell populations depends critically on genome-wide information on each cell type. Here, we report single-cell transcriptome profiling of over 6800 freshly dispersed anterior pituitary cells from postpubertal male and female rats. Six pituitary-specific cell types were identified based on known marker genes and characterized: folliculostellate cells and hormone producing corticotrophs, gonadotrophs, thyrotrophs, somatotrophs, and lactotrophs. Also identified were endothelial and blood cells from the pituitary capillary network. The expression of numerous developmental and neuroendocrine marker genes in both folliculostellate and hormone producing cells supports that they have a common origin. For several genes, the validity of transcriptome analysis was confirmed by qRT-PCR and single cell immunocytochemistry. Folliculostellate cells exhibit impressive transcriptome diversity, indicating their major roles in production of endogenous ligands and detoxification enzymes, and organization of extracellular matrix. Transcriptome profiles of hormone producing cells also indicate contributions toward those functions, while also clearly demonstrating their endocrine function. This survey highlights many novel genetic markers contributing to pituitary cell type identity, sexual dimorphism, and function and points to relationships between hormone producing and folliculostellate cells.
Project description:The obesity incidence is increasing worldwide with the urgent need to identify new therapeutics. Obesity is associated with endocrine alterations, arising from changes in the hypothalamic-pituitary hormone axes, leading to reproductive disorders, altered basal metabolism and stress hormone production. The focus of this study was to determine if diet induced obesity alters pituitary gland plasticity, gene expression and hormone production and secretion. Here we performed single cell RNA-sequencing (scRNA-seq) on pituitary glands from control (CTRL) and high fat diet (HFD) fed males and looked at cell type population dynamics and gene expression changes between HFD and CTRL for all hormone-producing cell types. Our study revealed diet-induced changes in pituitary gland plasticity and hormone production that may play a role in altered hormone production in obese patients and consequently, dysregulation of pituitary gland homeostasis.
Project description:The anterior pituitary is comprised of distinct cell types that each secrete specific hormones to control a variety of biological processes including growth, metabolism, reproduction and stress responses. The anterior pituitary shows a remarkable level of cell type plasticity that allows shifts in hormone producing populations to meet organismal demands. Pituitary cell plasticity is tightly regulated and both deficiency in cell plasticity and excessive cell plasticity are associated with common pituitary pathologies. The molecular mechanisms underlying this plasticity are not well characterized but recent work has implicated the stem cell determinants and sequence-specific mRNA binding proteins of the Musashi family as regulators of adult pituitary hormone production. In this study we have sought to identify the full range of Musashi target mRNAs in the adult mouse pituitary. Using Musashi RNA immunoprecipitation we identify a cohort of 1192 mRNAs that show specific Musashi binding. These include mRNAs restricted to discrete hormone-producing cell lineages as well as mRNAs associated with stem and progenitor cells. The processes influenced by the proteins encoded by the Musashi-associated mRNAs include cellular homeostasis, protein trafficking and secretion, unfolded protein response, endocrine processes and female pregnancy. Functional analysis of validated mRNA regulatory 3' untranslated regions (3’ UTRs) reveals UTR-specific positive or negative control by the Musashi proteins within the same cellular context. Together, our findings indicate a broad role for Musashi proteins in the control of pituitary function.
Project description:The mammalian pituitary gland is a complex organ consisting of hormone-producing cells, anterior lobe folliculostellate cells (FSCs), posterior lobe pituicytes, vascular pericytes and endothelial cells, and Sox2-expressing stem cells. We present single-cell RNA sequencing and immunohistofluorescence analyses of pituitary cells of adult female rats with a focus on the transcriptomic profiles of nonhormonal cell types. Samples obtained from whole pituitaries and separated anterior and posterior lobe cells contained all expected pituitary resident cell types and lobe-specific vascular cell subpopulations. FSCs and pituicytes expressed S100B, ALDOC, EAAT1, ALDH1A1, and VIM genes and proteins, as well as other astroglial marker genes, some common and some cell type-specific. We also found that the SOX2 gene and protein were expressed in ~15% of pituitary cells, including FSCs, pituicytes, and a fraction of hormone-producing cells, arguing against its stem cell specificity. FSCs comprised two Sox2-expressing subclusters; FS1 contained more cells but lower genetic diversity, while FS2 contained proliferative cells, shared genes with hormone-producing cells, and expressed genes consistent with stem cell niche formation, regulation of cell proliferation and stem cell pluripotency, including the Hippo and Wnt pathways. FS1 cells were randomly distributed in the anterior and intermediate lobes, while FS2 cells were localized exclusively in the marginal zone between the anterior and intermediate lobes. These data indicate the identity of the FSCs as anterior pituitary-specific astroglia, with FS1 cells representing differentiated cells equipped for classical FSC roles and FS2 cells exhibiting additional stem cell-like features.
Project description:The anterior pituitary gland plays central roles in body growth, reproduction, metabolism and the stress response. In this study, we performed single-cell RNA-sequencing (scRNA-seq) of 4,113 individual cells from human fetal pituitaries. We characterized divergent developmental trajectories with distinct transitional intermediate states in five hormone-producing cell lineages. Furthermore, we characterized the cellular heterogeneity of pituitary stem cells, identifying a hybrid epithelial/mesenchymal state and an early-to-late state transition. These analyses define a single-cell resolution roadmap for human pituitary development.
Project description:Transcription factors and signaling pathways that regulate stem cells and specialized hormone-producing cells in the pituitary gland have been the subject of intense study and have yielded a mechanistic understanding of pituitary organogenesis and disease. Yet, the regulation of stem cell proliferation and differentiation, the heterogeneity among specialized hormone-producing cells, and the role of non-endocrine cells in the gland remain important, unanswered questions. Recent advances in single-cell RNA sequencing (scRNAseq) technologies provide new avenues to address these questions. We performed scRNAseq on approximately 13,663 cells pooled from six whole pituitary glands of 7-week-old C57BL/6 male mice. We identified pituitary endocrine and stem cells in silico, as well as other support cell-types such as endothelia, connective tissue, and red and white blood cells. Differential gene expression analyses identify known and novel markers of pituitary endocrine and stem cell populations. We demonstrate the value of scRNAseq by in vivo validation of a novel gonadotrope-enriched marker, Foxp2. We present novel scRNAseq data of in vivo pituitary tissue, including data from agnostic clustering algorithms which suggest the presence of a somatotrope subpopulation enriched in sterol/cholesterol synthesis genes. At the same time, we show that incomplete transcriptome annotation can cause false negatives on some scRNAseq platforms that only generate 3’ transcript end sequences, and use in vivo data to recover reads of the pituitary transcription factor Prop1. Ultimately, scRNAseq technologies represent a significant opportunity to address longstanding questions regarding the development and function of the different populations of the pituitary gland throughout life.
Project description:Gene alteration analysis on 121 GH-producing pituitary adenomas and non-target proteomics analysis with RNA sequencing analysis on 45 non-functioning pituitary adenomas (NFPAs) and 60 growth hormone (GH)-producing pituitary adenomas were performed, and integrated these results with the clinical characteristics of acromegaly. We attempted to identify key players involved in shaping the clinical features of acromegaly, especially those related to treatment efficacy. This project revealed the importance of GNAS mutations in terms of clinical and biochemical characteristics and identified novel molecules that may be involved in the responsiveness to medical treatment.
Project description:The differentiation of the hormone-producing cell lineages of the anterior pituitary represents an informative model of mammalian cell fate determination. The generation and maintenance of two of these lineages, the growth hormone (GH) producing somatotropes and prolactin (PRL) producing lactotropes, is dependent on the pituitary-specific POU-homeo domain transcription factor, POU1F1. While POU1F1 is expressed in both cell types, and plays a direct and essential role in the activation of both the Gh and Prl genes, GH expression is restricted to somatotropes and PRL expression is restricted to lactotropes. These observations imply the existence of additional, cell type-enriched factors, that contribute to the somatotrope and lactotrope cell identities. Here, we use a set of transgenic mouse models to facilitate sorting of somatotrope and lactotrope populations based on the expression of distinct fluorescent markers expressed under Gh and Prl gene transcriptional controls, respectively. The transcriptomic analyses reveal a concordance of gene expression profiles in the two populations. The limited number of divergent mRNAs between the two populations includes a set of transcription factors that may have roles in pituitary lineage divergence or in regulating the expression of key lineage-specific genes after lineage divergence. Four of these factors were validated for lineage enrichment at the level of protein expression, two somatotrope-enriched and two lactotrope-enriched, and three of these four factors were shown to have corresponding activities in appropriate enhancement or repression of landmark genes. These studies establish a useful database for further study of the somatotrope and lactotrope cells as well as identify novel regulators of lineage marker expression in the anterior pituitary.