Leptin: A Metabolic Signal for the Differentiation of Pituitary Cells

Pituitary cell function is impacted by metabolic states and therefore must receive signals that inform them about nutritional status or adiposity. A primary signal from adipocytes is leptin, which recent studies have shown regulates most pituitary cell types. Subsets of all pituitary cell types express leptin receptors and leptin has been shown to exert transcriptional control through classical JAK/STAT pathways. Recent studies show that leptin also signals through post-transcriptional pathways that involve the translational regulatory protein Musashi. Mechanistically, post-transcriptional control would permit rapid cellular regulation of critical pre-existing pituitary transcripts as energy states change. The chapter will review evidence for transcriptional and/or post-transcriptional regulation of leptin targets (including Gnrhr, activin, Fshb, Gh, Ghrhr, and Pou11f1) and the consequences of the loss of leptin signaling to gonadotrope and somatotrope functions.

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Control of secretion in anterior pituitary cells--linking ion channels, messengers and exocytosis

Journal of Experimental Biology ◽

10.1242/jeb.139.1.287 ◽

1988 ◽

Vol 139 (1) ◽

pp. 287-316

Author(s):

W. T. Mason ◽

S. R. Rawlings ◽

P. Cobbett ◽

S. K. Sikdar ◽

R. Zorec ◽

...

Keyword(s):

Ion Channels ◽

Intracellular Calcium ◽

Anterior Pituitary ◽

Hormone Secretion ◽

Cell Types ◽

Pituitary Cell ◽

Pituitary Cells ◽

Calcium Activity ◽

Anterior Pituitary Cells ◽

Voltage Dependent

Normal anterior pituitary cells, in their diversity and heterogeneity, provide a rich source of models for secretory function. However, until recently they have largely been neglected in favour of neoplastic, clonal tumour cell lines of pituitary origin, which have enabled a number of studies on supposedly homogeneous cell types. Because many of these lines appear to lack key peptide and neurotransmitter receptors, as well as being degranulated with accompanying abnormal levels of secretion, we have developed a range of normal primary anterior pituitary cell cultures using dispersion and enrichment techniques. By studying lactotrophs, somatotrophs and gonadotrophs we have revealed a number of possible transduction mechanisms by which receptors for hypothalamic peptides and neurotransmitters may control secretion. In particular, the transduction events controlling secretion from pituitary cells may differ fundamentally from those found in other cell types. Patch-clamp recordings in these various pituitary cell preparations have revealed substantial populations of voltage-dependent Na+, Ca2+ and K+ channels which may support action potentials in these cells. Although activation of these channels may gate Ca2+ entry to the cells under some conditions, our evidence taken with that of other laboratories suggests that peptide-receptor interactions leading to hormone secretion occur independently of significant membrane depolarization. Rather, secretion of hormone and rises in intracellular calcium measured with new probes for intracellular calcium activity, can occur in response to hypothalamic peptide activation in the absence of substantial changes in membrane potential. These changes in intracellular calcium activity almost certainly depend on both intracellular and extracellular calcium sources. In addition, strong evidence of a role for multiple intracellular receptors and modulators in the secretory event suggests we should consider the plasma membrane channels important for regulation of hormone secretion to be predominantly agonist-activated, rather than of the more conventional voltage-dependent type. Likewise, evidence from new methods for recording single ion channels suggests the existence of intracellular sites for channel modulation, implying they too may play an important role in secretory regulation. We shall consider new data and new technology which we hope will provide key answers to the many intriguing questions surrounding the control of pituitary hormone secretion. We shall highlight our work with recordings of single ion channels activated by peptides, and recent experiments using imaging of intracellular ionized free calcium.(ABSTRACT TRUNCATED AT 250 WORDS)

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SAT-298 Integrative Single-Cell Transcriptomic and Epigenomic Landscape of Mouse Anterior Pituitary Cell Types

Journal of the Endocrine Society ◽

10.1210/jendso/bvaa046.593 ◽

2020 ◽

Vol 4 (Supplement_1) ◽

Author(s):

Frederique Murielle Ruf-Zamojski ◽

Michel A Zamojski ◽

German Nudelman ◽

Yongchao Ge ◽

Natalia Mendelev ◽

...

Keyword(s):

Single Cell ◽

Cell Line ◽

Anterior Pituitary ◽

Cell Types ◽

Chromatin Accessibility ◽

Pituitary Cell ◽

Integrated Analysis ◽

Pituitary Cells ◽

Rna Seq ◽

Cell Type

Abstract The pituitary gland is a critical regulator of the neuroendocrine system. To further our understanding of the classification, cellular heterogeneity, and regulatory landscape of pituitary cell types, we performed and computationally integrated single cell (SC)/single nucleus (SN) resolution experiments capturing RNA expression, chromatin accessibility, and DNA methylation state from mouse dissociated whole pituitaries. Both SC and SN transcriptome analysis and promoter accessibility identified the five classical hormone-producing cell types (somatotropes, gonadotropes (GT), lactotropes, thyrotropes, and corticotropes). GT cells distinctively expressed transcripts for Cga, Fshb, Lhb, Nr5a1, and Gnrhr in SC RNA-seq and SN RNA-seq. This was matched in SN ATAC-seq with GTs specifically showing open chromatin at the promoter regions for the same genes. Similarly, the other classically defined anterior pituitary cells displayed transcript expression and chromatin accessibility patterns characteristic of their own cell type. This integrated analysis identified additional cell-types, such as a stem cell cluster expressing transcripts for Sox2, Sox9, Mia, and Rbpms, and a broadly accessible chromatin state. In addition, we performed bulk ATAC-seq in the LβT2b gonadotrope-like cell line. While the FSHB promoter region was closed in the cell line, we identified a region upstream of Fshb that became accessible by the synergistic actions of GnRH and activin A, and that corresponded to a conserved region identified by a polycystic ovary syndrome (PCOS) single nucleotide polymorphism (SNP). Although this locus appears closed in deep sequencing bulk ATAC-seq of dissociated mouse pituitary cells, SN ATAC-seq of the same preparation showed that this site was specifically open in mouse GT, but closed in 14 other pituitary cell type clusters. This discrepancy highlighted the detection limit of a bulk ATAC-seq experiment in a subpopulation, as GT represented ~5% of this dissociated anterior pituitary sample. These results identified this locus as a candidate for explaining the dual dependence of Fshb expression on GnRH and activin/TGFβ signaling, and potential new evidence for upstream regulation of Fshb. The pituitary epigenetic landscape provides a resource for improved cell type identification and for the investigation of the regulatory mechanisms driving cell-to-cell heterogeneity. Additional authors not listed due to abstract submission restrictions: N. Seenarine, M. Amper, N. Jain (ISMMS).

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Melatonin Regulates Somatotrope and Lactotrope Function Through Common and Distinct Signaling Pathways in Cultured Primary Pituitary Cells From Female Primates

Endocrinology ◽

10.1210/en.2014-1819 ◽

2015 ◽

Vol 156 (3) ◽

pp. 1100-1110 ◽

Cited By ~ 10

Author(s):

Alejandro Ibáñez-Costa ◽

José Córdoba-Chacón ◽

Manuel D. Gahete ◽

Rhonda D. Kineman ◽

Justo P. Castaño ◽

...

Keyword(s):

Calcium Channels ◽

Signaling Pathways ◽

Somatostatin Receptors ◽

Cell Types ◽

Pituitary Hormones ◽

Pituitary Cell ◽

Pituitary Cells ◽

Primate Model ◽

Direct Role ◽

Precise Relationship

Abstract Melatonin (MT) is secreted by the pineal gland and exhibits a striking circadian rhythm in its release. Depending on the species studied, some pituitary hormones also display marked circadian/seasonal patterns and rhythms of secretion. However, the precise relationship between MT and pituitary function remains controversial, and studies focusing on the direct role of MT in normal pituitary cells are limited to nonprimate species. Here, adult normal primate (baboons) primary pituitary cell cultures were used to determine the direct impact of MT on the functioning of all pituitary cell types from the pars distalis. MT increased GH and prolactin (PRL) expression/release in a dose- and time-dependent fashion, a response that was blocked by somatostatin. However, MT did not significantly affect ACTH, FSH, LH, or TSH expression/release. MT did not alter GHRH- or ghrelin-induced GH and/or PRL secretions, suggesting that MT may activate similar signaling pathways as ghrelin/GHRH. The effects of MT on GH/PRL release, which are likely mediated through MT1 receptor, involve both common (adenylyl cyclase/protein kinase A/extracellular calcium-channels) and distinct (phospholipase C/intracellular calcium-channels) signaling pathways. Actions of MT on pituitary cells also included regulation of the expression of other key components for the control of somatotrope/lactotrope function (GHRH, ghrelin, and somatostatin receptors). These results show, for the first time in a primate model, that MT directly regulates somatotrope/lactotrope function, thereby lending support to the notion that the actions of MT on these cells might substantially contribute to the define daily patterns of GH and PRL observed in primates and perhaps in humans.

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Cell Type-Specific Metabolism of Peptidylglycineα -Amidating Monooxygenase in Anterior Pituitary*

Endocrinology ◽

10.1210/endo.141.8.7620 ◽

2000 ◽

Vol 141 (8) ◽

pp. 3020-3034 ◽

Cited By ~ 8

Author(s):

Rajaa El Meskini ◽

Richard E. Mains ◽

Betty A. Eipper

Keyword(s):

Anterior Pituitary ◽

Secretory Granules ◽

Primary Cultures ◽

Cell Types ◽

Pituitary Cell ◽

Male Rat ◽

Pituitary Cells ◽

Cell Type ◽

Cell Content ◽

Monooxygenase Activity

Peptidylglycine α-amidating monooxygenase (PAM) is a bifunctional enzyme expressed in each major anterior pituitary cell type. We used primary cultures of adult male rat anterior pituitary to examine PAM expression, processing, and secretion in the different pituitary cell types and to compare these patterns to those observed in transfected AtT-20 corticotrope tumor cells. Immunostaining and subcellular fractionation identified PAM in pituitary secretory granules and additional vesicular compartments; in contrast, in AtT-20 cells, transfected PAM was primarily localized to the trans-Golgi network. PAM expression was highest in gonadotropes, with moderate levels in somatotropes and thyrotropes and lower levels in corticotropes and lactotropes. Under basal conditions, less than 1% of the cell content of monooxygenase activity was secreted per h, a rate comparable to the basal rate of release of individual pituitary hormones. General secretagogues stimulated PAM secretion 3- to 5-fold. Stimulation with specific hypothalamic releasing hormones demonstrated that different pituitary cell types secrete characteristic sets of PAM proteins. Gonadotropes and thyrotropes release primarily monofunctional monooxygenase. Somatotropes secrete primarily bifunctional PAM, whereas corticotropes secrete a mixture of mono- and bifunctional proteins. As observed in transfected AtT-20 cells, pituitary cells rapidly internalize the PAM/PAM-antibody complex from the cell surface. The distinctly different steady-state localizations of endogenous PAM in primary pituitary cells and transfected PAM in AtT-20 cell lines may simply reflect the increased storage capacity of primary pituitary cells.

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Control of the anterior pituitary cell lineage regulator POU1F1 by the stem cell determinant Musashi

Endocrinology ◽

10.1210/endocr/bqaa245 ◽

2020 ◽

Author(s):

Melody Allensworth-James ◽

Jewel Banik ◽

Angela Odle ◽

Linda Hardy ◽

Alex Lagasse ◽

...

Keyword(s):

Stem Cell ◽

Translational Control ◽

Anterior Pituitary ◽

Transcriptional Control ◽

Mrna Translation ◽

Stem Cell Marker ◽

Pituitary Cells ◽

Control Female ◽

Leptin Signaling ◽

Leptin Receptors

Abstract The adipokine leptin regulates energy homeostasis through ubiquitously expressed leptin receptors. Leptin has a number of major signaling targets in the brain, including cells of the anterior pituitary (AP). We have previously reported that mice lacking leptin receptors in AP somatotropes display growth hormone (GH) deficiency, metabolic dysfunction and adult onset obesity. Amongst other targets, leptin signaling promotes increased levels of the pituitary transcription factor POU1F1 which, in turn, regulates the specification of somatotrope, lactotrope and thyrotrope cell lineages within the AP. Leptin’s mechanism of action on somatotropes is sex-dependent, with females demonstrating post-transcriptional control of Pou1f1 mRNA translation. Here, we report that the stem cell marker and mRNA translational control protein, Musashi1, exerts repression of the Pou1f1 mRNA. In female somatotropes, Msi1 mRNA and protein levels are increased in the mouse model that lacks leptin signaling (Gh-CRE Lepr-null), coincident with lack of POU1f1 protein, despite normal levels of Pou1f1 mRNA. Single-cell RNA sequencing of pituitary cells from control female animals indicates that both Msi1 and Pou1f1 mRNAs are expressed in Gh-expressing somatotropes and immunocytochemistry confirms that Musashi1 protein is present in the somatotrope cell population. We demonstrate that Musashi interacts directly with the Pou1f1 mRNA 3’ untranslated region and exerts translational repression of a Pou1f1 mRNA translation reporter in a leptin-sensitive manner. Musashi immunoprecipitation from whole pituitary reveals co-associated Pou1f1 mRNA. These findings suggest a mechanism in which leptin stimulation is required to reverse Musashi-mediated Pou1f1 mRNA translational control to coordinate AP somatotrope function with metabolic status.

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How treatments with endocrine and metabolic drugs influence pituitary cell function

Endocrine Connections ◽

10.1530/ec-19-0482 ◽

2020 ◽

Vol 9 (2) ◽

pp. R14-R27 ◽

Cited By ~ 2

Author(s):

Giovanni Tulipano

Keyword(s):

Protein Kinase ◽

Mammalian Cells ◽

Cell Function ◽

Cell Metabolism ◽

Cell Signalling ◽

Pituitary Cell ◽

Pituitary Cells ◽

Transduction Mechanisms ◽

Amp Activated Protein Kinase

A variety of endocrine and metabolic signals regulate pituitary cell function acting through the hypothalamus-pituitary neuroendocrine axes or directly at the pituitary level. The underlying intracellular transduction mechanisms in pituitary cells are still debated. AMP-activated protein kinase (AMPK) functions as a cellular sensor of low energy stores in all mammalian cells and promotes adaptive changes in response to calorie restriction. It is also regarded as a target for therapy of proliferative disorders. Various hormones and drugs can promote tissue-specific activation or inhibition of AMPK by enhancing or inhibiting AMPK phosphorylation, respectively. This review explores the preclinical studies published in the last decade that investigate the role of AMP-activated protein kinase in the intracellular transduction pathways downstream of endocrine and metabolic signals or drugs affecting pituitary cell function, and its role as a target for drug therapy of pituitary proliferative disorders. The effects of the hypoglycemic agent metformin, which is an indirect AMPK activator, are discussed. The multiple effects of metformin on cell metabolism and cell signalling and ultimately on cell function may be either dependent or independent of AMPK. The in vitro effects of metformin may also help highlighting differences in metabolic requirements between pituitary adenomatous cells and normal cells.

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Estrogen Actions on Lactotroph Proliferation Are Independent of a Paracrine Interaction with Other Pituitary Cell Types: A Study Using Lactotroph-Enriched Cells

Endocrinology ◽

10.1210/en.2006-1484 ◽

2007 ◽

Vol 148 (7) ◽

pp. 3131-3139 ◽

Cited By ~ 16

Author(s):

Maho Ishida ◽

Wakaba Takahashi ◽

Susumu Itoh ◽

Shigetaka Shimodaira ◽

Shuichiro Maeda ◽

...

Keyword(s):

Fluorescent Protein ◽

Cell Types ◽

Cell Interaction ◽

Pituitary Cell ◽

Pituitary Cells ◽

Dependent Manner ◽

Paracrine Factor ◽

Mitogenic Action ◽

Estrogen Receptor Positive ◽

Green Fluorescent

The mitogenic action of estrogen on estrogen-responsive tissues is suggested to be mediated by paracrine growth factors secreted from neighboring estrogen receptor-positive cells. Using pituitary lactotrophs in primary culture, on which estrogen exerts both mitogenic and antimitogenic actions in a cell context-dependent manner, we investigated whether a paracrine cell-to-cell interaction with other pituitary cell types was required for estrogen action. In pituitary cells, enriched for lactotrophs by 85% using differential sedimentation on a discontinuous Percoll gradient, 17β-estradiol (E2) showed an antimitogenic action on lactotrophs in the presence of IGF-I, which was similar to that in control unenriched cells. Mitogenic actions were also seen in lactotroph-enriched cells when E2 was administered alone, in combination with serum, or in combination with the adenylate cyclase activator forskolin. Similar results were obtained in 90% lactotroph-enriched cells collected by fluorescence-activated cell sorting from transgenic rats expressing enhanced green fluorescent protein under the control of the prolactin promoter. The putative role of basic fibroblast growth factor (bFGF) as a paracrine factor mediating the mitogenic action of estrogen was not supported by the results that: 1) bFGF inhibited lactotroph proliferation; 2) immunoneutralization of bFGF failed to block E2-induced proliferation; and 3) cellular bFGF levels were not altered by E2 treatment. These results suggest that the antimitogenic and mitogenic actions of estrogen on lactotrophs do not require paracrine signals from other pituitary cell types and that estrogen directly influences lactotroph proliferation.

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Novel insights into how purines regulate pituitary cell function

Clinical Science ◽

10.1042/cs20030053 ◽

2003 ◽

Vol 104 (5) ◽

pp. 467-481 ◽

Cited By ~ 16

Author(s):

D. Aled REES ◽

Maurice F. SCANLON ◽

Jack HAM

Keyword(s):

Pituitary Gland ◽

Cell Function ◽

Adenine Nucleotides ◽

Growth Control ◽

Cell Types ◽

Pituitary Cell ◽

Receptor Subtypes ◽

Diverse Range ◽

Surface Receptors ◽

Signalling Molecules

Purine nucleosides and nucleotides are widely distributed substances that exhibit a diverse range of effects in a number of tissues, acting as important extracellular signalling molecules in addition to their more established roles in cellular metabolism. They mediate their effects via activation of distinct cell surface receptors, termed adenosine (or P1) and P2 purinergic receptors. Although roles for adenosine and adenine nucleotides have been described previously in the pituitary gland, the distribution of the receptor subtypes and the effects of their activation on pituitary function are not well defined. Recent evidence, however, has emerged to describe a complex signalling system for purines in the pituitary gland. Data from a variety of studies have shown that the expression pattern, number and affinity of adenosine and/or P2 receptors may be cell-type specific and that non-endocrine in addition to endocrine cells elaborate these receptors. These variations, along with the diverse range of signalling pathways activated, dictate the response of individual cell types to extracellular purines, with roles now emerging for these substances in the regulation of hormone release, pituitary cell proliferation and cytokine/growth factor expression. In this review, we discuss these advances and examine some implications for pituitary growth control and the response of the hypothalamic–pituitary–adrenal axis to stress and inflammation.

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The gp130 Cytokines Interleukin-11 and Ciliary Neurotropic Factor Regulate through Specific Receptors the Function and Growth of Lactosomatotropic and Folliculostellate Pituitary Cell Lines*

Endocrinology ◽

10.1210/endo.141.5.7442 ◽

2000 ◽

Vol 141 (5) ◽

pp. 1746-1753 ◽

Cited By ~ 13

Author(s):

Carolina Perez Castro ◽

Alberto Carbia Nagashima ◽

Marcelo Páez Pereda ◽

Victoria Goldberg ◽

Alberto Chervin ◽

...

Keyword(s):

Cell Line ◽

Messenger Rna ◽

Anterior Pituitary ◽

Cell Function ◽

Pituitary Cell ◽

Angiogenic Factor ◽

Gh3 Cells ◽

Pituitary Cells ◽

Anterior Pituitary Cells ◽

Neurotropic Factor

Abstract Two of the most potent cytokines regulating anterior pituitary cell function are leukemia inhibitory factor and interleukin-6 (IL-6), which belong to the cytokine receptor family using the common gp130 signal transducer. We studied the actions of two other members of this family, IL-11 and ciliary neurotropic factor (CNTF), on folliculostellate (FS) cells (TtT/GF cell line) and lactosomatotropic cells (GH3 cell line). The messenger RNA (mRNA) for the α-chain specific for the IL-11 receptor (1.7 kb) and CNTF receptor (2 kb) are expressed on both cell types. In addition, we detected CNTF receptor mRNA in normal rat anterior pituitary cells. IL-11 (1.25–5 nm) dose dependently stimulated the proliferation of FS cells. CNTF, at doses from 0.4–2 nm, also significantly stimulated the growth of these cells. In addition, both cytokines significantly stimulated proliferation of lactosomatotropic GH3 cells, and CNTF stimulated hormone production (GH and PRL) at 24 h by these cells. At 16–72 h, IL-11 stimulates the secretion of the angiogenic factor vascular endothelial growth factor by FS cells. In addition, both GH3 and FS cells express CNTF mRNA. These data suggest that IL-11 and CNTF may act as growth and regulatory factors in anterior pituitary cells.

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NK3R Mediates the EGF-Induced SLα Secretion and mRNA Expression in Grass Carp Pituitary

International Journal of Molecular Sciences ◽

10.3390/ijms20010091 ◽

2018 ◽

Vol 20 (1) ◽

pp. 91 ◽

Cited By ~ 2

Author(s):

Xiangfeng Qin ◽

Cheng Ye ◽

Xiaoyun Zhou ◽

Jingyi Jia ◽

Shaohua Xu ◽

...

Keyword(s):

Mrna Expression ◽

Grass Carp ◽

Cell Function ◽

Cell Types ◽

Pituitary Cells ◽

Dependent Manner ◽

Lower Vertebrates ◽

Mrna And Protein Expression

Epidermal growth factor (EGF) is a potent regulator of cell function in many cell types. In mammals, the EGF/EGFR system played an important role in both pituitary physiology and pathology. However, it is not clear about the pituitary action of EGF in lower vertebrates. In this study, using grass carp as a model, we found that EGF could stimulate NK3R mRNA and protein expression through pituitary ErbB1 and ErbB2 coupled to MEK/ERK and PI3K/Akt/mTOR pathways. In addition, EGF could also induce pituitary somatolactin α (SLα) secretion and mRNA expression in a dose- and time-dependent manner in vivo and in vitro. The stimulatory actions of EGF on SLα mRNA expression were also mediated by PI3K/Akt/mTOR and MEK/ERK pathways coupled to ErbB1 and ErbB2 activation. Our previous study has reported that neurokinin B (NKB) could also induce SLα secretion and mRNA expression in carp pituitary cells. In the present study, interestingly, we found that EGF could significantly enhance NKB-induced SLα mRNA expression. Further studies found that NK3R antagonist SB222200 could block EGF-induced SLα mRNA expression, indicating an NK3R requirement. Furthermore, cAMP/PKA inhibitors and PLC/PKC inhibitors could both abolish EGF- and EGF+NKB-induced SLα mRNA expression, which further supported that EGF-induced SLα mRNA expression is NK3R dependent.

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