Project description:Organ architecture is established during development through specific cell:cell contacts. The mechanisms responsible for these specific cell interactions remain poorly understood. In order to address this question, we used the anterior pituitary gland that harbors five different and interdigitated hormone-secreting homotypic cell networks. We now report that blocking differentiation of the first lineage to arise during pituitary development, the corticotrope cells, leads to pituitary hypoplasia with a major effect on the somatotrope cells that are fewer, with less secretory granules and a loss of cell polarity. These somatotrope cell phenotypes are dependent on gene dosage for the corticotrope-restricted transcription factor Tpit. In addition, the Tpit-deficient pituitary is hyper-vascularized. Single cell transcriptomics identifiy corticotrope and somatotrope regulatory and signaling pathways that may underlie cell:cell communications responsible for these phenotypes. Collectively, the results indicate that the corticotrope cell network is an important paracrine signalling center regulating pituitary architecture and size.
Project description:POU1F1 regulates, in the pituitary, the development of the prolactin-, growth hormone- and thyrotropin ß-expressing lineages and the expression of these hormone in the mature pituitary through the direct regulation of their promoters. Besides these functions, POU1F1 is also involved in other cellular processes in the pituitary, such as cell division and survival, but the genomic targets involved in these actions are not known. The present ChIP-chip study identified a large number of hitherto unknown potential direct targets that might be involved in these actions, such as Tcf4, Lmo4, Pax6, Trp53 etc. ChIP-chip was done from pregnant female mouse (C57Bl/6J) pituitary (3 pools of 12 pituitary anterior lobes, corresponding to three biological replicates) with POU1F1 (PIT-1)
Project description:POU1F1 regulates, in the pituitary, the development of the prolactin-, growth hormone- and thyrotropin ß-expressing lineages and the expression of these hormone in the mature pituitary through the direct regulation of their promoters. Besides these functions, POU1F1 is also involved in other cellular processes in the pituitary, such as cell division and survival, but the genomic targets involved in these actions are not known. The present ChIP-chip study identified a large number of hitherto unknown potential direct targets that might be involved in these actions, such as Tcf4, Lmo4, Pax6, Trp53 etc.
Project description:The transcription factor ISL1 is expressed in pituitary gland stem cells and the thyrotrope and gonadotrope lineages. Pituitary-specific Isl1 deletion causes hypopituitarism with increased stem cell apoptosis, reduced differentiation of thyrotropes and gonadotropes, and reduced body size. Conditional Isl1 deletion causes development of multiple Rathke’s cleft-like cysts, with 100% penetrance. Foxa1 and Foxj1 are abnormally expressed in the pituitary gland and associated with a ciliogenic gene expression program in the cysts. We confirmed expression of FOXA1, FOXJ1 and stem cell markers in human Rathke's cleft cyst tissue, but not craniopharyngiomas, which suggests these transcription factors are useful, pathological markers for diagnosis of Rathke's cleft cysts. These studies support a model whereby expression of ISL1 in pituitary progenitors drives differentiation into thyrotropes and gonadotropes, and without it, activation of FOXA1 and FOXJ1 permits development of an oral epithelial cell fate with mucinous cysts. This pituitary-specific Isl1 mouse knockout sheds light on the etiology of Rathke's cleft cysts and the role of ISL1 in normal pituitary development.
Project description:Single cell transcriptomic analysis of pituitary gland from adult zebrafish that had specifically cells labeled with endoderm lineage by different strategies. The goal of this study is to examine the contribution of endoderm derived cell in the pituitary of vertebrate animals.
Project description:The purpose of this research is to determine whether the drug, Bevacizumab (a monoclonal anti VEGF-A antibody), which is approved to treat patients with metastatic colon cancer induces hyperprolactinemia (increased prolactin secretion) in humans with intact pituitary function. Past studies have shown Bevacizumab to shrink tumor size and also increase prolactin levels. The mechanism of the hyperprolactinemia might be inhibition of pituitary portal vein transport, suggesting that Bevacizumab induces prolactin secretion from normal lactotrophs in the pituitary gland.
Patients who have been treated with Bevacizumab for at least one month will be recruited to participate.
The subjects who are being treated with Bevacizumab by Dr. Stephen Wolin (a sub-investigator) will be screened by him for study eligibility. Dr. Wolin will approach eligible patients with all the information and background of the study and see if they have an interest in being consented.
If consented, there will be 2 blood draws for the research that is not part of their standard care in which 10 ml of blood is collected and prolactin, growth hormone, IGF-I, TSH, thyroxine, ACTH, and cortisol will be measured. One 5ml blood draw will occur before the administration of Bevacizumab and the second 5 ml blood draw will occur after the administration of the Bevacizumab. The investigators will then review the laboratory results. The blood tests are of the hormones of the pituitary gland to test pituitary function and see if there are any abnormalities with the secretions of the gland. Pituitary function abnormalities and hyperprolactinemia are diagnosed by looking at hormone levels in the blood and comparing them to the normal reference ranges.
This study will only involve 10 subjects and will be conducted entirely at Cedars-Sinai Medical Center.
Project description:Deployment of a cell-specifying enhancer repertoire by the pioneer factor Pax7 The establishment and maintenance of cell identity depends on implementation of stable cell-specific chromatin landscapes. Pioneer transcription factors establish new cell fate competences by triggering chromatin remodeling during development. Here, we used pituitary cell specification to define the salient features of pioneer action. Comparison of purified pituitary cells of different lineages showed that chromatin accessibility differs at enhancers rather than promoters. The pioneer factor Pax7 specifies one pituitary lineage identity by opening a specific repertoire of enhancers that are distinct from the myogenic targets of Pax7. Pax7 binds its pioneer targets rapidly and days before chromatin remodeling and gene activation. Finally, enhancers opened by Pax7-dependent chromatin remodeling exhibit loss of DNA methylation and they acquire long term epigenetic memory. The present work identifies enhancer pioneering as a critical feature for cell fate specification and maintenance.
Project description:Deployment of a cell-specifying enhancer repertoire by the pioneer factor Pax7 The establishment and maintenance of cell identity depends on implementation of stable cell-specific chromatin landscapes. Pioneer transcription factors establish new cell fate competences by triggering chromatin remodeling during development. Here, we used pituitary cell specification to define the salient features of pioneer action. Comparison of purified pituitary cells of different lineages showed that chromatin accessibility differs at enhancers rather than promoters. The pioneer factor Pax7 specifies one pituitary lineage identity by opening a specific repertoire of enhancers that are distinct from the myogenic targets of Pax7. Pax7 binds its pioneer targets rapidly and days before chromatin remodeling and gene activation. Finally, enhancers opened by Pax7-dependent chromatin remodeling exhibit loss of DNA methylation and they acquire long term epigenetic memory. The present work identifies enhancer pioneering as a critical feature for cell fate specification and maintenance.