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Mirczuk SM, Scudder CJ, Read JE, Crossley VJ, Regan JT, Richardson KM, Simbi B, McArdle CA, Church DB, Fenn J, Kenny PJ, Volk HA, Wheeler-Jones CP, Korbonits M, Niessen SJ, McGonnell IM, Fowkes RC. Natriuretic Peptide Expression and Function in GH3 Somatolactotropes and Feline Somatotrope Pituitary Tumours. Int J Mol Sci 2021; 22:ijms22031076. [PMID: 33499110 PMCID: PMC7865297 DOI: 10.3390/ijms22031076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/14/2021] [Accepted: 01/20/2021] [Indexed: 11/17/2022] Open
Abstract
Patients harbouring mutations in genes encoding C-type natriuretic peptide (CNP; NPPC) or its receptor guanylyl cyclase B (GC-B, NPR2) suffer from severe growth phenotypes; loss-of-function mutations cause achondroplasia, whereas gain-of-function mutations cause skeletal overgrowth. Although most of the effects of CNP/GC-B on growth are mediated directly on bone, evidence suggests the natriuretic peptides may also affect anterior pituitary control of growth. Our previous studies described the expression of NPPC and NPR2 in a range of human pituitary tumours, normal human pituitary, and normal fetal human pituitary. However, the natriuretic peptide system in somatotropes has not been extensively explored. Here, we examine the expression and function of the CNP/GC-B system in rat GH3 somatolactotrope cell line and pituitary tumours from a cohort of feline hypersomatotropism (HST; acromegaly) patients. Using multiplex RT-qPCR, all three natriuretic peptides and their receptors were detected in GH3 cells. The expression of Nppc was significantly enhanced following treatment with either 100 nM TRH or 10 µM forskolin, yet only Npr1 expression was sensitive to forskolin stimulation; the effects of forskolin and TRH on Nppc expression were PKA- and MAPK-dependent, respectively. CNP stimulation of GH3 somatolactotropes significantly inhibited Esr1, Insr and Lepr expression, but dramatically enhanced cFos expression at the same time point. Oestrogen treatment significantly enhanced expression of Nppa, Nppc, Npr1, and Npr2 in GH3 somatolactotropes, but inhibited CNP-stimulated cGMP accumulation. Finally, transcripts for all three natriuretic peptides and receptors were expressed in feline pituitary tumours from patients with HST. NPPC expression was negatively correlated with pituitary tumour volume and SSTR5 expression, but positively correlated with D2R and GHR expression. Collectively, these data provide mechanisms that control expression and function of CNP in somatolactotrope cells, and identify putative transcriptional targets for CNP action in somatotropes.
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Affiliation(s)
- Samantha M. Mirczuk
- Endocrine Signalling Group, Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK; (S.M.M.); (C.J.S.); (J.E.R.); (V.J.C.); (J.T.R.); (K.M.R.)
- Comparative Biomedical Sciences, Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK; (B.S.); (C.P.W.-J.); (I.M.M.)
| | - Christopher J. Scudder
- Endocrine Signalling Group, Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK; (S.M.M.); (C.J.S.); (J.E.R.); (V.J.C.); (J.T.R.); (K.M.R.)
- Clinical Sciences & Services, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK; (D.B.C.); (J.F.); (P.J.K.); (H.A.V.); (S.J.N.)
| | - Jordan E. Read
- Endocrine Signalling Group, Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK; (S.M.M.); (C.J.S.); (J.E.R.); (V.J.C.); (J.T.R.); (K.M.R.)
- Comparative Biomedical Sciences, Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK; (B.S.); (C.P.W.-J.); (I.M.M.)
| | - Victoria J. Crossley
- Endocrine Signalling Group, Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK; (S.M.M.); (C.J.S.); (J.E.R.); (V.J.C.); (J.T.R.); (K.M.R.)
- Comparative Biomedical Sciences, Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK; (B.S.); (C.P.W.-J.); (I.M.M.)
| | - Jacob T. Regan
- Endocrine Signalling Group, Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK; (S.M.M.); (C.J.S.); (J.E.R.); (V.J.C.); (J.T.R.); (K.M.R.)
| | - Karen M. Richardson
- Endocrine Signalling Group, Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK; (S.M.M.); (C.J.S.); (J.E.R.); (V.J.C.); (J.T.R.); (K.M.R.)
| | - Bigboy Simbi
- Comparative Biomedical Sciences, Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK; (B.S.); (C.P.W.-J.); (I.M.M.)
| | - Craig A. McArdle
- Department of Translational Science, Bristol Medical School, University of Bristol, Whitson Street, Bristol BS1 3NY, UK;
| | - David B. Church
- Clinical Sciences & Services, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK; (D.B.C.); (J.F.); (P.J.K.); (H.A.V.); (S.J.N.)
| | - Joseph Fenn
- Clinical Sciences & Services, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK; (D.B.C.); (J.F.); (P.J.K.); (H.A.V.); (S.J.N.)
| | - Patrick J. Kenny
- Clinical Sciences & Services, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK; (D.B.C.); (J.F.); (P.J.K.); (H.A.V.); (S.J.N.)
- Small Animal Specialist Hospital, 1 Richardson Place, North Ryde, 2113 NSW, Australia
| | - Holger A. Volk
- Clinical Sciences & Services, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK; (D.B.C.); (J.F.); (P.J.K.); (H.A.V.); (S.J.N.)
- Department of Small Animal Medicine and Surgery, University of Veterinary Medicine Hannover, Bünteweg 9, 30559 Hannover, Germany
| | - Caroline P. Wheeler-Jones
- Comparative Biomedical Sciences, Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK; (B.S.); (C.P.W.-J.); (I.M.M.)
| | - Márta Korbonits
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK;
| | - Stijn J. Niessen
- Clinical Sciences & Services, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK; (D.B.C.); (J.F.); (P.J.K.); (H.A.V.); (S.J.N.)
| | - Imelda M. McGonnell
- Comparative Biomedical Sciences, Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK; (B.S.); (C.P.W.-J.); (I.M.M.)
| | - Robert C. Fowkes
- Endocrine Signalling Group, Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK; (S.M.M.); (C.J.S.); (J.E.R.); (V.J.C.); (J.T.R.); (K.M.R.)
- Comparative Biomedical Sciences, Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK; (B.S.); (C.P.W.-J.); (I.M.M.)
- Correspondence: ; Tel.: +11-44-207-468-1215
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Natriuretic peptide activation of extracellular regulated kinase 1/2 (ERK1/2) pathway by particulate guanylyl cyclases in GH3 somatolactotropes. Cell Tissue Res 2017; 369:567-578. [PMID: 28451751 PMCID: PMC5579180 DOI: 10.1007/s00441-017-2624-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 04/04/2017] [Indexed: 12/24/2022]
Abstract
The natriuretic peptides, Atrial-, B-type and C-type natriuretric peptides (ANP, BNP, CNP), are regulators of many endocrine tissues and exert their effects predominantly through the activation of their specific guanylyl cyclase receptors (GC-A and GC-B) to generate cGMP. Whereas cGMP-independent signalling has been reported in response to natriuretic peptides, this is mediated via either the clearance receptor (Npr-C) or a renal-specific NPR-Bi isoform, which both lack intrinsic guanylyl cyclase activity. Here, we report evidence of GC-B-dependent cGMP-independent signalling in pituitary GH3 cells. Stimulation of GH3 cells with CNP resulted in a rapid and sustained enhancement of ERK1/2 phosphorylation (P-ERK1/2), an effect that was not mimicked by dibutryl-cGMP. Furthermore, CNP-stimulated P-ERK1/2 occurred at concentrations below that required for cGMP accumulation. The effect of CNP on P-ERK1/2 was sensitive to pharmacological blockade of MEK (U0126) and Src kinases (PP2). Silencing of the GC-B1 and GC-B2 splice variants of the GC-B receptor by using targeted short interfering RNAs completely blocked the CNP effects on P-ERK1/2. CNP failed to alter GH3 cell proliferation or cell cycle distribution but caused a concentration-dependent increase in the activity of the human glycoprotein α-subunit promoter (αGSU) in a MEK-dependent manner. Finally, CNP also activated the p38 and JNK MAPK pathways in GH3 cells. These findings reveal an additional mechanism of GC-B signalling and suggest additional biological roles for CNP in its target tissues.
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Homologous and heterologous desensitization of guanylyl cyclase-B signaling in GH3 somatolactotropes. Cell Tissue Res 2013; 355:425-36. [PMID: 24352806 PMCID: PMC3921447 DOI: 10.1007/s00441-013-1763-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 11/01/2013] [Indexed: 01/12/2023]
Abstract
The guanylyl cyclases, GC-A and GC-B, are selective receptors for atrial and C-type natriuretic peptides (ANP and CNP, respectively). In the anterior pituitary, CNP and GC-B are major regulators of cGMP production in gonadotropes and yet mouse models of disrupted CNP and GC-B indicate a potential role in growth hormone secretion. In the current study, we investigate the molecular and pharmacological properties of the CNP/GC-B system in somatotrope lineage cells. Primary rat pituitary and GH3 somatolactotropes expressed functional GC-A and GC-B receptors that had similar EC50 properties in terms of cGMP production. Interestingly, GC-B signaling underwent rapid homologous desensitization in a protein phosphatase 2A (PP2A)-dependent manner. Chronic exposure to either CNP or ANP caused a significant down-regulation of both GC-A- and GC-B-dependent cGMP accumulation in a ligand-specific manner. However, this down-regulation was not accompanied by alterations in the sub-cellular localization of these receptors. Heterologous desensitization of GC-B signaling occurred in GH3 cells following exposure to either sphingosine-1-phosphate or thyrotrophin-releasing hormone (TRH). This heterologous desensitization was protein kinase C (PKC)-dependent, as pre-treatment with GF109203X prevented the effect of TRH on CNP/GC-B signaling. Collectively, these data indicate common and distinct properties of particulate guanylyl cyclase receptors in somatotropes and reveal that independent mechanisms of homologous and heterologous desensitization occur involving either PP2A or PKC. Guanylyl cyclase receptors thus represent potential novel therapeutic targets for treating growth-hormone-associated disorders.
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Abstract
In the rat anterior pituitary gland, estrogen increases both prolactin (PRL) mRNA levels and stimulates the proliferation of PRL-producing cells. The temporal sequence of these events suggests that PRL gene expression may be coordinated with cell proliferation. We investigated the relationship between cell cycle progression and the accumulation of the PRL mRNA, as well as several other mRNAs, in the rat pituitary tumor GH3 cell line. Serum-deprived cells progressed from G0 to S phase in 20-24 h following serum stimulation. During this time, beta-actin mRNA levels increased 7-fold in 5 h, then returned to basal levels prior to the beginning of S phase. Histone H1 mRNA levels increased approximately 3-fold as cells entered S phase. These data are consistent with the cell cycle-dependent regulation of beta-actin and histone H1 gene expression reported for other cell types. Glucocorticoid receptor mRNA levels were barely detectable in serum-deprived cells but rapidly increased 3- to 5-fold following serum stimulation. This increase resulted in glucocorticoid receptor mRNA levels that were equivalent to those seen in cells maintained in serum-containing medium, suggesting that serum factors regulate glucocorticoid receptor gene expression. In contrast to these changes in gene expression, the levels of PRL and growth hormone (GH) mRNAs gradually increased 2-fold while the cells progressed through G1 phase. Similarly, in cells synchronized to progress through S and G2 phases following aphidicolin treatment, histone H1 gene expression showed a specific increase in S phase cells, whereas PRL and GH mRNA levels changed little with cell cycle progression. These results indicate that the levels of PRL and GH mRNAs are not regulated in a cell cycle-dependent manner. When changes in estrogen responsiveness were determined during the cell cycle, we found that estradiol treatment was capable of increasing PRL mRNA accumulation independent of cell cycle progression and cell cycle distribution in synchronized GH3 cells. These results support the hypothesis that the hormonal regulation of PRL gene expression is not significantly affected by cell growth.
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Affiliation(s)
- P R Rhode
- Department of Chemistry, California Institute of Technology, Pasadena 91125
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Weisman AS, Tixier-Vidal A, Gourdji D. Thyrotropin-releasing hormone increases the levels of c-fos and beta-actin mRNA in GH3/B6 pituitary tumor cells. IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY : JOURNAL OF THE TISSUE CULTURE ASSOCIATION 1987; 23:585-90. [PMID: 3114226 DOI: 10.1007/bf02620977] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The effects of thyrotropin-releasing hormone (TRH) on the mRNA levels of c-fos, N-myc, beta-actin and prolactin (PRL) were studied in GH3/B6 cells, a rat pituitary cell line. TRH has previously been shown to increase biosynthesis and release of PRL, and to stimulate PRL gene transcription (13,19) in these cells. All experiments were performed on quiescent serum-deprived cells, and under these conditions, addition of TRH stimulated PRL production but did not alter cellular proliferation. Simultaneously, TRH induced time- and concentration-dependent increases in c-fos and beta-actin mRNA levels, with peak responses at 30 min and 4 h, respectively, in a dose range from 1 nM to 100 nM. The TRH effects on N-myc mRNA levels were less consistent. Addition of serum to quiescent GH3/B6 cells induced (3-5 fold) increases in c-fos, beta-actin and PRL mRNAs which differed in magnitude and kinetics when compared to TRH stimulation. Serum did not alter N-myc mRNA levels. The TRH-induced increases in c-fos and beta-actin mRNA may play a role in the secretory response.
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