ABSTRACT
Irisin is a hormone secreted by muscle in response to exercise. The irisin receptor (IrisinR) is a heterodimer of integrin alpha V (ITGAV) and integrin beta 5 (ITGB5) subunits. Since irisin may mediate some beneficial effects of exercise on animal reproduction, we tested the hypothesis that bovine gonadotrophs express IrisinR and irisin stimulates luteinizing hormone (LH) and follicle stimulating hormone (FSH) secretion by gonadotrophs. Reverse transcription polymerase chain reaction was used to detect the mRNA expression of both ITGAV and ITGB5 in the anterior pituitary glands (APs) of post pubertal heifers and mouse gonadotroph cell line "LßT2." Western blotting was used to detect protein expression in bovine APs. Immunofluorescence microscopy, utilizing the same antibody, visualized IrisinR on the plasma membrane of majority of gonadotrophs. We prepared AP cells from healthy postpubertal heifers, cultured them for 3.5 d, and treated them with increasing concentrations (0, 0.01, 0.1, 1, or 10â¯nM) of irisin for 5â¯min before either no treatment or gonadotropin-releasing hormone (GnRH) stimulation. After 2â¯h, media were harvested for LH and FSH assays. Irisin (0.1-10â¯nM) stimulated basal LH and FSH secretion, and these stimulatory effects were inhibited by the extracellular signal-regulated kinase or SMAD pathway inhibitors. In the presence of GnRH, irisin at 0.01-1â¯nM stimulated LH and FSH secretion. A higher dose of irisin (10â¯nM), however, suppressed the GnRH-induced LH and FSH levels. In conclusion, bovine gonadotrophs expressed IrisinR, and irisin controlled LH and FSH secretion from bovine gonadotrophs.
Subject(s)
Fibronectins , Follicle Stimulating Hormone , Gonadotrophs , Luteinizing Hormone , Animals , Cattle , Female , Mice , Fibronectins/metabolism , Follicle Stimulating Hormone/metabolism , Gene Expression Regulation/drug effects , Gene Expression Regulation/physiology , Gonadotrophs/metabolism , Gonadotrophs/drug effects , Gonadotropin-Releasing Hormone/metabolism , Luteinizing Hormone/metabolism , Physical Conditioning, Animal/physiologyABSTRACT
The gonadotrope cells within the pituitary control vital processes of reproduction by producing follicle stimulating hormone (FSH) and luteinizing hormone (LH). Both external stimuli and internal regulatory factors contribute to the regulation of gonadotrope development and function. In recent years, growing evidences indicate that microRNAs (miRNAs), which regulate gene expression post-transcriptionally, play critical roles in multiple processes of gonadotrope development and function, including the syntheses of α or ß subunits of FSH and LH, the secretion of LH, the regulation of GnRH signaling, and the maintenance of gonadotrope cell kinetics. Here, we review recent advances of miRNAs' expression, functions and mechanisms approached by using miRNA knockout mouse models, in silico analysis and the in vitro cultures of primary pituitary cells and gonadotrope-derived cell lines. By summarizing and discussing different roles of miRNAs in gonadotropes, this minireview helps to gain insights into the complex molecular network in gonadotropes and reproduction.
Subject(s)
Gonadotrophs , MicroRNAs , Animals , MicroRNAs/genetics , MicroRNAs/metabolism , Gonadotrophs/metabolism , Follicle Stimulating Hormone/metabolism , Mice , Luteinizing Hormone/metabolism , Pituitary Gland/metabolism , HumansABSTRACT
The mammalian pituitary gland drives highly conserved physiological processes such as somatic cell growth, pubertal transformation, fertility, and metabolism by secreting a variety of hormones. Recently, single-cell transcriptomics techniques have been used in pituitary gland research. However, more studies have focused on adult pituitary gland tissues from different species or different sexes, and no research has yet resolved cellular differences in pituitary gland tissue before and after sexual maturation. Here, we identified a total of 15 cell clusters and constructed single-cell transcriptional profiles of rats before and after sexual maturation. Furthermore, focusing on the gonadotrope cluster, 106 genes were found to be differentially expressed before and after sexual maturation. It was verified that Spp1, which is specifically expressed in gonadotrope cells, could serve as a novel marker for this cell cluster and has a promotional effect on the synthesis and secretion of follicle-stimulating hormone. The results provide a new resource for further resolving the regulatory mechanism of pituitary gland development and pituitary hormone synthesis and secretion.
Subject(s)
Gonadotrophs , Pituitary Gland , Sexual Maturation , Single-Cell Analysis , Animals , Rats , Sexual Maturation/genetics , Pituitary Gland/metabolism , Gonadotrophs/metabolism , Single-Cell Analysis/methods , Male , Female , Biomarkers/metabolism , Transcriptome , Gene Expression Profiling , Follicle Stimulating Hormone/metabolismABSTRACT
MAPK activating death domain (MADD) is a multifunctional protein regulating small GTPases RAB3 and RAB27, MAPK signaling, and cell survival. Polymorphisms in the MADD locus are associated with glycemic traits, but patients with biallelic variants in MADD manifest a complex syndrome affecting nervous, endocrine, exocrine, and hematological systems. We identified a homozygous splice site variant in MADD in 2 siblings with developmental delay, diabetes, congenital hypogonadotropic hypogonadism, and growth hormone deficiency. This variant led to skipping of exon 30 and in-frame deletion of 36 amino acids. To elucidate how this mutation causes pleiotropic endocrine phenotypes, we generated relevant cellular models with deletion of MADD exon 30 (dex30). We observed reduced numbers of ß cells, decreased insulin content, and increased proinsulin-to-insulin ratio in dex30 human embryonic stem cell-derived pancreatic islets. Concordantly, dex30 led to decreased insulin expression in human ß cell line EndoC-ßH1. Furthermore, dex30 resulted in decreased luteinizing hormone expression in mouse pituitary gonadotrope cell line LßT2 but did not affect ontogeny of stem cell-derived GnRH neurons. Protein-protein interactions of wild-type and dex30 MADD revealed changes affecting multiple signaling pathways, while the GDP/GTP exchange activity of dex30 MADD remained intact. Our results suggest MADD-specific processes regulate hormone expression in pancreatic ß cells and pituitary gonadotropes.
Subject(s)
Insulin-Secreting Cells , Insulin-Secreting Cells/metabolism , Humans , Animals , Mice , Male , Gonadotrophs/metabolism , Female , RNA Splice Sites/genetics , Cell Line , Insulin/metabolism , Siblings , Exons/genetics , rab3 GTP-Binding Proteins/metabolism , rab3 GTP-Binding Proteins/genetics , Hypogonadism/genetics , Hypogonadism/metabolism , Hypogonadism/pathologyABSTRACT
In mammals reproduction is regulated by many factors, among others by the peptides belonging to the RFamide peptide family. However, the knowledge concerning on the impact of recently identified member of this family (QRFP43) on the modulation of the gonadotrophic axis activity is still not fully understood and current research results are ambiguous. In the present study we tested the in vivo effect of QRFP43 on the secretory activity of the gonadotrophic axis at the hypothalamic-pituitary level in Polish Merino sheep. The animals (n = 48) were randomly divided into three experimental groups: controls receiving an icv infusion of Ringer-Locke solution, group receiving icv infusion of QRFP43 at 10 µg per day and 50 µg per day. All sheep received four 50 min icv infusions at 30 min intervals, on each of three consecutive days. Hypothalamic and pituitaries were collected and secured for further immunohistochemical and molecular biological analysis. In addition, during the experiment a blood samples have been collected for subsequent RIA determinations. QRFP43 was found to downregulate Kiss mRNA expression in the MBH and reduce the level of IR material in ME. This resulted in a reduction of GnRH IR material in the ME. QRFP43 increased plasma FSH levels while decreasing LH levels. Our findings indicate that QRFP43 inhibits the activity of the gonadotropic axis in the ovine at the level of the hypothalamus and may represent another neuromodulator of reproductive processes in animals.
Subject(s)
Gonadotrophs , Luteinizing Hormone , Female , Sheep , Animals , Gonadotropin-Releasing Hormone/metabolism , Hypothalamus/metabolism , Pituitary Gland/metabolism , Gonadotrophs/metabolism , Follicle Stimulating Hormone , Mammals/metabolismABSTRACT
INTRODUCTION: This study sought to decipher the mechanism of transitions between life-history stages in a seasonally reproducing subtropical finch, Amandava amandava delineating the plasticity of the gonadotropes (LH cells), lactotropes (PRL cells), and thyrotropes (TSH cells) in the pituitary gland including the pars tuberalis, with regard to the in situ expression, morphological characteristics, and alteration in the plasma levels of hormones. METHODS: Immunohistochemistry of LH, PRL, TSH cells, morphometry and densitometry of expressed hormones (Image J software analysis), and ELISA for plasma hormonal levels were performed. RESULTS: LH, PRL, and TSH cells showed remarkable plasticity during the annual seasonal reproductive cycle. In the PT, all the 3 cell types were detected during the breeding phase, with additional detection of the TSH immunoreactivity during the pre-breeding and the PRL immunoreactivity during post-breeding phases. Pars distalis (PD) expressions and the plasma levels of the LH and TSH were at the peak during the breeding phase, but the PRL peak was during the post-breeding phase. In addition to PRL in the neurohypophysis and in the median eminence, hypothalamic PRL, and TSH were also elucidated. CONCLUSIONS: This study suggests activation of the gonadal axis by the PT TSH which might transduce seasonal cues, but not specifically photoperiod, in the birds of the tropics/subtropics. Post-breeding phase sustained high plasma TSH and peak plasma PRL might coordinate the transition to the non-breeding phase including the trigger of parental care as the later hormone assigned with. Hypothalamic TSH and PRL might influence events of seasonality through central modulation.
Subject(s)
Finches , Gonadotrophs , Luteinizing Hormone , Prolactin , Reproduction , Seasons , Thyrotropin , Animals , Reproduction/physiology , Luteinizing Hormone/blood , Luteinizing Hormone/metabolism , Gonadotrophs/metabolism , Gonadotrophs/physiology , Prolactin/blood , Prolactin/metabolism , Finches/physiology , Thyrotropin/blood , Thyrotropin/metabolism , Lactotrophs/metabolism , Lactotrophs/physiology , Male , Pituitary Gland, Anterior/metabolism , Female , Thyrotrophs/metabolism , Thyrotrophs/physiologyABSTRACT
Single same cell RNAseq/ATACseq multiome data provide unparalleled potential to develop high resolution maps of the cell-type specific transcriptional regulatory circuitry underlying gene expression. We present CREMA, a framework that recovers the full cis-regulatory circuitry by modeling gene expression and chromatin activity in individual cells without peak-calling or cell type labeling constraints. We demonstrate that CREMA overcomes the limitations of existing methods that fail to identify about half of functional regulatory elements which are outside the called chromatin 'peaks'. These circuit sites outside called peaks are shown to be important cell type specific functional regulatory loci, sufficient to distinguish individual cell types. Analysis of mouse pituitary data identifies a Gata2-circuit for the gonadotrope-enriched disease-associated Pcsk1 gene, which is experimentally validated by reduced gonadotrope expression in a gonadotrope conditional Gata2-knockout model. We present a web accessible human immune cell regulatory circuit resource, and provide CREMA as an R package.
Subject(s)
Gonadotrophs , Pituitary Gland , Mice , Humans , Animals , Pituitary Gland/metabolism , Gonadotrophs/metabolism , Chromatin/genetics , Chromatin/metabolism , Regulatory Sequences, Nucleic AcidABSTRACT
Since 2017, hormone-negative pituitary neuroendocrine tumors expressing the steroidogenic factor SF1 have been recognized as gonadotroph tumors (GnPT) but have been poorly studied. To further characterize their bio-clinical spectrum, 54 GnPT defined by immunostaining for FSH and/or LH (group 1, n = 41) or SF1 only (group 2, n = 13) were compared and studied for SF1, ßFSH, ßLH, CCNA2, CCNB1, CCND1, caspase 3, D2R, and AIP gene expression by qRT-PCR. Immunohistochemistry for AIP and/or D2R was performed in representative cases. Overall, patients were significantly younger in group 1 (P = 0.040 vs group 2), with a similar trend excluding recurrent cases (P = 0.078), and no significant difference in gender, tumor size, invasion or Ki67. SF1 expression was similar in both groups but negatively correlated with the patient's age (P = 0.013) and positively correlated with ßLH (P < 0.001) expression. Beta-FSH and AIP were significantly higher in group 1 (P = 0.042 and P = 0.024, respectively). Ki67 was unrelated to gonadotroph markers but positively correlated with CCNB1 (P = 0.001) and negatively correlated with CCND1 (P = 0.008). D2R and AIP were strongly correlated with each other (P < 0.001), and both positively correlated with SF1, ßFSH, ßLH, and CCND1. AIP immunopositivity was frequently observed in both groups, with a similar median score, and unrelated to Ki67. D2R immunostaining was best detected with a polyclonal antibody and mostly cytoplasmic. This study indicates that hormone-negative GnPT tend to occur in older patients but do not significantly differ from other GnPT in terms of invasion or proliferation. It also points out the current limits of D2R immunostaining in such tumors.
Subject(s)
Gonadotrophs , Pituitary Neoplasms , Humans , Aged , Pituitary Neoplasms/pathology , Gonadotrophs/metabolism , Gonadotrophs/pathology , Ki-67 Antigen/metabolism , Follicle Stimulating Hormone , World Health OrganizationABSTRACT
Pituitary gland function is regulated by the activity of various transcription factors that control cell fate decisions leading to cellular differentiation and hormone production. FOXO1 is necessary for normal somatotrope differentiation and function. Recent in vivo data implicate FOXO1 in the regulation of genes important for somatotrope differentiation including Gh1, Neurod4, and Pou1f1. In the current study, the somatotrope-like cell line GH3 was treated with a FOXO1 inhibitor, resulting in significant reduction in Neurod4 and Gh1 expression. Consistent with these findings, CRISPR/Cas9-mediated deletion of Foxo1 in GH3 cells significantly reduced expression of Gh1 and Neurod4. Chromatin immunoprecipitation sequencing identifies novel FOXO1 binding sites associated with the Neurod4, Gh1, and Pou1f1 genes. The FOXO1 binding site in the Neurod4 gene exhibits enhancer activity in somatotrope-like cells but not in gonadotrope-like cells. These data strongly suggest FOXO1 directly contributes to the transcriptional control of genes important for somatotrope differentiation.
Subject(s)
Gonadotrophs , Pituitary Gland , Pituitary Gland/metabolism , Forkhead Box Protein O1/genetics , Forkhead Box Protein O1/metabolism , Gene Expression Regulation , Cell Differentiation/genetics , Transcription Factors/metabolism , Gonadotrophs/metabolismABSTRACT
Postnatal development of functional pituitary gonadotrophs is necessary for maturation of the hypothalamic-pituitary-gonadal axis, puberty, and reproduction. Here we examined the role of PI4-kinase A, which catalyzes the biosynthesis of PI4P in mouse reproduction by knocking out this enzyme in cells expressing the gonadotropin-releasing hormone (GnRH) receptor. Knockout (KO) mice were infertile, reflecting underdeveloped gonads and reproductive tracts and lack of puberty. The number and distribution of hypothalamic GnRH neurons and Gnrh1 expression in postnatal KOs were not affected, whereas Kiss1/kisspeptin expression was increased. KO of PI4-kinase A also did not alter embryonic establishment and neonatal development and function of the gonadotroph population. However, during the postnatal period, there was a progressive loss of expression of gonadotroph-specific genes, including Fshb, Lhb, and Gnrhr, accompanied by low gonadotropin synthesis. The postnatal gonadotroph population also progressively declined, reaching approximately one-third of that observed in controls at 3 months of age. In these residual gonadotrophs, GnRH-dependent calcium signaling and calcium-dependent membrane potential changes were lost, but intracellular administration of inositol-14,5-trisphosphate rescued this signaling. These results indicate a key role for PI4-kinase A in the postnatal development and maintenance of a functional gonadotroph population.
Subject(s)
Gonadotrophs , Pituitary Diseases , Mice , Animals , Gonadotrophs/metabolism , Mice, Knockout , Sexual Maturation , Pituitary Gland/metabolism , Gonadotropin-Releasing Hormone/genetics , Gonadotropin-Releasing Hormone/metabolism , Pituitary Diseases/metabolismABSTRACT
OBJECTIVE: Functioning gonadotroph adenomas (FGAs) are rare pituitary tumours stimulating ovarian function with potential life-threatening consequences in women. However, a lack of aggregated clinical experience of FGAs impairs management in affected women. The aim of this study is to present the clinical course of FGA-induced ovarian hyperstimulation syndrome (OHSS) cases as identified by some of the largest UK pituitary endocrine tertiary centres with a view to increasing awareness and improving diagnosis and management of women with FGA. DESIGN: A retrospective observational study; audit of eight UK regional pituitary centres for cases of FGAs. SETTING: Specialist neuroendocrine centres in the United Kingdom. PATIENTS AND MEASUREMENTS: Women diagnosed with FGA-induced OHSS. Description of their clinical course. RESULTS: Seven cases of FGA were identified in women, all causing OHSS. Mean age was 33.4 years at diagnosis. Abdominal pain, irregular periods, headache, and visual disturbances were reported at presentation by 100%, 71%, 57% and 43% of women, respectively. Three of seven women underwent ovarian surgery before FGA diagnosis. Six women underwent transsphenoidal surgery (TSS) with incomplete tumour resection in five of those, but all showed improvement or resolution in symptoms and biochemistry postoperatively. CONCLUSION: FGA is a rare cause of spontaneous OHSS. TSS improves clinical and biochemical features of ovarian hyperstimulation in FGAs. Improved awareness of FGA will prevent inappropriate emergency ovarian surgery.
Subject(s)
Adenoma , Gonadotrophs , Ovarian Hyperstimulation Syndrome , Pituitary Neoplasms , Female , Humans , Adult , Pituitary Neoplasms/surgery , Ovarian Hyperstimulation Syndrome/etiology , Adenoma/pathology , Disease ProgressionABSTRACT
The anterior pituitary controls key biological processes, including growth, metabolism, reproduction, and stress responses through distinct cell types that each secrete specific hormones. The anterior pituitary cells show a remarkable level of cell type plasticity that mediates the shifts in hormone-producing cell populations that are required to meet organismal needs. The molecular mechanisms underlying pituitary cell plasticity are not well understood. Recent work has implicated the pituitary stem cell populations and specifically, the mRNA binding proteins of the Musashi family in control of pituitary cell type identity. In this study we have identified the target mRNAs that mediate Musashi function in the adult mouse pituitary and demonstrate the requirement for Musashi function in vivo. Using Musashi RNA immunoprecipitation, we identify a cohort of 1184 mRNAs that show specific Musashi binding. Identified Musashi targets include the Gnrhr mRNA, which encodes the gonadotropin-releasing hormone receptor (GnRHR), and the Fshb mRNA, encoding follicle-stimulating hormone (FSH). Reporter assays reveal that Musashi functions to exert repression of translation of the Fshb mRNA, in addition to the previously observed repression of the Gnrhr mRNA. Importantly, mice engineered to lack Musashi in gonadotropes demonstrate a failure to repress translation of the endogenous Gnrhr and Fshb mRNAs during the estrous cycle and display a significant heterogeneity in litter sizes. The range of identified target mRNAs suggests that, in addition to these key gonadotrope proteins, Musashi may exert broad regulatory control over the pituitary proteome in a cell type-specific manner.
Subject(s)
Gonadotrophs , Mice , Animals , Gonadotrophs/metabolism , Follicle Stimulating Hormone/metabolism , Carrier Proteins/metabolism , Protein Biosynthesis/genetics , RNA, Messenger/genetics , RNA, Messenger/metabolismABSTRACT
Ethanolamine plasmalogens (EPls) are the only known ligands of a novel receptor, G protein-coupled receptor 61, and bovine brain EPls stimulate follicle-stimulating hormone (FSH) but not luteinizing hormone (LH), secreted by bovine gonadotrophs. We hypothesized that the brain EPls of whales (Balaenoptera edeni), another Cetartiodactyla with at least twice the lifespan of bovines, could stimulate FSH secretion by gonadotrophs. To test this hypothesis, bovine gonadotrophs (from approximately 2-year-old Japanese Black heifers) were cultured for 3.5 days and treated with increasing concentrations of brain EP1s from whales (approximately 22 years old). FSH and LH secretion was stimulated by all tested concentrations of whale EPls (p < 0.05). To clarify the important differences between bovine and whale EPls, we utilized two-dimensional liquid chromatography-mass spectrometry, which revealed 35 peaks. Among them, we observed significant differences between 12 EPl molecular species. Additionally, we identified differentially expressed genes for enzymes involved in EPl synthesis or degradation in the hypothalamus of young heifers and old cows (approximately 10 years old) as compared to whales (approximately 28 years old) via deep sequencing of the transcriptome. We conclude that whale brains contain unique EPls that stimulate both FSH and LH secretion by bovine gonadotrophs.
Subject(s)
Gonadotrophs , Pituitary Gland, Anterior , Cattle , Animals , Female , Follicle Stimulating Hormone/metabolism , Gonadotrophs/metabolism , Whales/metabolism , Gonadotropin-Releasing Hormone , Brain/metabolism , Pituitary Gland, Anterior/metabolismABSTRACT
Gonadotropes in the anterior pituitary gland are essential for fertility and provide a functional link between the brain and the gonads. To trigger ovulation, gonadotrope cells release massive amounts of luteinizing hormone (LH). The mechanism underlying this remains unclear. Here, we utilize a mouse model expressing a genetically encoded Ca2+ indicator exclusively in gonadotropes to dissect this mechanism in intact pituitaries. We demonstrate that female gonadotropes exclusively exhibit a state of hyperexcitability during the LH surge, resulting in spontaneous [Ca2+]i transients in these cells, which persist in the absence of any in vivo hormonal signals. L-type Ca2+ channels and transient receptor potential channel A1 (TRPA1) together with intracellular reactive oxygen species (ROS) levels ensure this state of hyperexcitability. Consistent with this, virus-assisted triple knockout of Trpa1 and L-type Ca2+ subunits in gonadotropes leads to vaginal closure in cycling females. Our data provide insight into molecular mechanisms required for ovulation and reproductive success in mammals.
Subject(s)
Gonadotrophs , Pituitary Gland, Anterior , Mice , Animals , Female , Luteinizing Hormone , Pituitary Gland , Ovulation , MammalsABSTRACT
BACKGROUND: Some patients develop immunoglobulin G4 (IgG4)-related hypophysitis associated with systemic diseases. More than 30 cases of IgG4-related hypophysitis have been reported. However, biopsy has rarely been performed in these patients, and none have had an associated pituitary neuroendocrine tumor (PitNET). We present a case of concurrent IgG4-related hypophysitis and PitNET. CASE PRESENTATION: A 56-year-old Japanese man arrived at the hospital with visual impairment, bitemporal hemianopia, and right abducens nerve palsy. Magnetic resonance imaging revealed pituitary body and stalk swelling as well as a small poorly enhanced right anterior lobe mass. Laboratory and loading test results suggested hypopituitarism. Because IgG4 level was elevated, a systemic examination was performed; multiple nodules were found in both lung fields. The diagnosis was based on an endoscopic transnasal biopsy of the pituitary gland. A histopathological examination revealed a marked infiltration of plasma cells into the pituitary gland, which was strongly positive for IgG4. The histological features of the resected tumor were consistent with those of gonadotroph PitNET, which was immunohistochemically positive for follicle-stimulating hormone-ß and steroidogenic factor-1, and no plasma cell infiltration was observed. Based on the histopathological examination results, steroid therapy was initiated, which reduced pituitary gland size and serum IgG4 levels. DISCUSSION AND CONCLUSIONS: This is the first reported case of IgG4-related hypophysitis with PitNET. Although no pathological findings indicating a relationship between the two conditions were found, we were able to preoperatively differentiate multiple lesions via detailed diagnostic imaging.
Subject(s)
Autoimmune Hypophysitis , Gonadotrophs , Hypophysitis , Neuroendocrine Tumors , Pituitary Diseases , Pituitary Neoplasms , Male , Humans , Middle Aged , Autoimmune Hypophysitis/complications , Autoimmune Hypophysitis/diagnosis , Autoimmune Hypophysitis/pathology , Gonadotrophs/pathology , Neuroendocrine Tumors/complications , Neuroendocrine Tumors/diagnosis , Neuroendocrine Tumors/pathology , Pituitary Gland/diagnostic imaging , Pituitary Gland/pathology , Pituitary Diseases/complications , Hypophysitis/diagnosis , Hypophysitis/diagnostic imaging , Pituitary Neoplasms/diagnosis , Pituitary Neoplasms/diagnostic imaging , Immunoglobulin GABSTRACT
PURPOSE: Transforming growth factor-beta receptor 3-like (TGFBR3L) is a pituitary enriched membrane protein selectively detected in gonadotroph cells. TGFBR3L is named after transforming growth factor-beta receptor 3 (TGFBR3), an inhibin A co-receptor in mice, due to sequence identity to the C-terminal region. We aimed to characterize TGFBR3L detection in a well-characterized, prospectively collected cohort of non-functioning pituitary neuroendocrine tumours (NF-PitNETs) and correlate it to clinical data. METHODS: 144 patients operated for clinically NF-PitNETs were included. Clinical, radiological and biochemical data were recorded. Immunohistochemical (IHC) staining for FSHß and LHß was scored using the immunoreactive score (IRS), TGFBR3L and TGFBR3 were scored by the percentage of positive stained cells. RESULTS: TGFBR3L staining was selectively present in 52% of gonadotroph tumours. TGFBR3L was associated to IRS of LHß (median 2 [IQR 0-3] in TGFBR3L negative and median 6 [IQR 3-9] in TGFBR3L positive tumours, p < 0.001), but not to the IRS of FSHß (p = 0.32). The presence of TGFBR3L was negatively associated with plasma gonadotropin concentrations in males (P-FSH median 5.5 IU/L [IQR 2.9-9.6] and median 3.0 [IQR 1.8-5.6] in TGFBR3L negative and positive tumours respectively, p = 0.008) and P-LH (median 2.8 IU/L [IQR 1.9-3.7] and median 1.8 [IQR 1.1-3.0] in TGFBR3L negative and positive tumours respectively, p = 0.03). TGFBR3 stained positive in 22% (n = 25) of gonadotroph tumours with no correlation to TGFBR3L. CONCLUSION: TGFBR3L was selectively detected in half (52%) of gonadotroph NF-PitNETs. The association to LHß staining and plasma gonadotropins suggests that TGFBR3L may be involved in hormone production in gonadotroph NF-PitNETs.
Subject(s)
Gonadotrophs , Neuroendocrine Tumors , Pituitary Neoplasms , Male , Animals , Mice , Gonadotrophs/metabolism , Pituitary Neoplasms/pathology , Gonadotropins , Transforming Growth Factors/metabolism , Follicle Stimulating HormoneABSTRACT
The 2 pituitary gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), regulate the reproductive function in all vertebrates. While many studies have investigated the regulation of gonadotropin production and release by sex steroid feedback, its role on the regulation of gonadotrope cell number remains unclear. Using medaka as a model and an optimized protocol to restore physiological sex steroids levels following gonadectomy, we show that gonadal sex steroids not only decrease fshb transcript levels, but also Fsh cell number in both sexes. We then investigated the origin of Fsh cell hyperplasia induced by gonadectomy. In both sexes, bromodeoxyuridine incubation shows that this is achieved via Fsh cell mitosis. In situ hybridization reveals that new Fsh cells also originate from transdifferentiating Tsh cells in females, but not in males. Both phenomena are inhibited by sex steroid supplementation via feeding. In males (but not females), gonadectomy (without recovery with sex steroid supplementation) also reduces sox2 transcript levels and Sox2-immunopositive population size, suggesting that Sox2 progenitors may be recruited to produce new Fsh cells. Opposite to Fsh cells, gonadectomy decreases lhb levels in both sexes, and levels are not restored by sex steroid supplementation. In addition, the regulation of Lh cell number also seems to be sex dependent. Removal of gonadal sex steroids stimulates Lh cell mitosis in male (like Fsh cells) but not in females. To conclude, our study provides the first evidence on sexually dimorphic mechanisms used in the fish pituitary to remodel gonadotrope populations in response to sex steroids.
Subject(s)
Gonadotrophs , Oryzias , Female , Animals , Male , Cell Transdifferentiation , Hyperplasia , Follicle Stimulating Hormone/pharmacology , Follicle Stimulating Hormone/genetics , Pituitary Gland , Gonadal Steroid Hormones/pharmacology , Steroids , MitosisABSTRACT
Pituitary tumours are benign neoplasms that derive from hormone-producing cells of the pituitary gland. While medical treatments have emerged for most subtypes, gonadotroph tumours that express follicle-stimulating hormone (FSH) and/or luteinizing hormone still lack therapeutic options apart from surgery and radiotherapy. Activin ligands are physiological regulators of production and secretion of FSH by gonadotroph cells, but their role in gonadotroph tumourigenesis remains little explored. Using the LßT2 mouse gonadotroph cell line which produces FSH under activin stimulation, we first tested whether subcutaneous xenografts of LßT2 cells resulted in tumour formation in Rag2KO mice. Histological analysis confirmed the presence of LßT2 tumours with endothelial cells and macrophages in their microenvironment. FSH expression was found in a subset of clusters of LßT2 cells in the tumours. We subsequently addressed the consequences of targeting activin signalling via injection of a soluble activin decoy receptor (sActRIIB-Fc). sActRIIB-Fc treatment resulted in significantly decreased LßT2 tumour volume. Reduced Smad2 phosphorylation as well as inhibition of tumour-induced FSH production confirmed the efficient targeting of activin-downstream signalling in treated tumours. More interestingly, treated tumours showed significantly fewer endothelial cells associated with reduced Vegfa expression. In vitro treatment of LßT2 cells with sActRIIB-Fc had no effect on cell proliferation or apoptosis, but Vegfa expression was inhibited, pointing to a likely paracrine effect of LßT2 cells on endothelial cells through activin-mediated Vegfa regulation. Further in vitro and in vivo studies are now needed to pinpoint the exact roles of activin signalling in these processes prior to translating these observations to the clinic.
Subject(s)
Gonadotrophs , Pituitary Neoplasms , Mice , Humans , Animals , Activins/metabolism , Gonadotrophs/metabolism , Pituitary Neoplasms/metabolism , Endothelial Cells/metabolism , Follicle Stimulating Hormone, beta Subunit/metabolism , Follicle Stimulating Hormone, beta Subunit/pharmacology , Follicle Stimulating Hormone/metabolism , Follicle Stimulating Hormone/pharmacology , Pituitary Gland/metabolism , Tumor MicroenvironmentABSTRACT
Kisspeptin-neurokinin B-dynorphin A (KNDy) neurons in the arcuate nucleus (ARC) regulate pulsatile luteinizing hormone (LH) secretion. These neurons express estrogen receptors and are negatively regulated by estrogen. This study aimed to determine whether estrogen supplementation after short-term ovariectomy-induced estrogen depletion has different effects on KNDy neurons depending on the timing of the supplementation. To decrease endogenous estradiol (E2) for a short time, adult female rats received a tube filled with E2 one week after ovariectomy and utilized it one week later (O1w + E). From the results of immunohistochemistry, the response to E2 was attenuated in KNDy neurons of O1w + E rats. Enlarged LH-secreting cells in the anterior pituitary were found in O1w + E rats; however, such enlarged LH cells were not found in ones without previous short-term E2 depletion. From the analysis of LH pulses, plasma LH levels were increased in O1w + E rats relative to ones without previous short-term E2 depletion. These results suggested that once endogenous sex steroids were depleted, the response to E2 in hypothalamic KNDy neurons did not fully recover in one week. Thus, short-term sex steroid depletion due to gonadectomy could alter the response to the sex steroids in KNDy neurons even though the period without sex steroids is only one week, and the alteration is likely to affect plasma hormone levels.
Subject(s)
Gonadotrophs , Neurokinin B , Rats , Female , Animals , Neurokinin B/metabolism , Dynorphins/metabolism , Gonadotrophs/metabolism , Kisspeptins/metabolism , Luteinizing Hormone , Estrogens , Arcuate Nucleus of Hypothalamus , Neurons/metabolism , Gonadotropin-Releasing HormoneABSTRACT
Kisspeptin modulates GnRH secretion in mammals and peripheral administration of 10-amino acid fragment of kisspeptin (Kp10) induces LH release and ovulation in cattle. Experiments were done to determine if iv administration of kisspeptin will activate GnRH neurons (i.e., after crossing the blood-brain barrier) and if pre-treatment with a GnRH receptor blocker will alter kisspeptin-induced LH release (from gonadotrophs) and ovulation. In Experiment 1, cows (n = 3 per group) were given human-Kisspeptin10 (hKp10; 3 x 15 mg iv at 60-min intervals) or normal saline and euthanized 150 min after treatment was initiated. Every 20th free-floating section (50 µm thickness) from the preoptic area to hypothalamus was double immunostained to colocalize GnRH- (DAB) and activated neurons (cFOS; Nickel-DAB). Kisspeptin induced plasma LH release from 15 to 150 min (P = 0.01) but the proportion of activated GnRH neurons did not differ between groups (5.8% and 3.5%, respectively; P = 0.11). Immunogold electron microscopy detected close contacts between kisspeptin fibers and GnRH terminals in the median eminence. In Experiment 2, pubertal heifers (n = 5 per group) were treated with 1) hKp10 iv, 2) Cetrorelix (GnRH antagonist; im) + hKp10 iv or 3) saline on Day 6 of the follicular wave under low-progesterone condition. A rise in plasma LH concentration was detected from 15 to 240 min in the hKp10 group but not in cetrorelix or control group (P<0.001). Ovulations were detected only in the hKp10 group (4/5; P = 0.02). Cetrorelix treatment was associated with regression of the preovulatory dominant follicle and emergence of a new follicular wave 3.4±0.75 days after the treatment in all five heifers. Results support the hypothesis that the effect of peripheral kisspeptin is mediated downstream of GnRH synthesis and does not involve GnRH-independent LH release from gonadotrophs. Peripheral kisspeptin may release pre-synthesized GnRH from the nerve terminals in areas outside the blood-brain barrier.