1
|
Kawahara M, Iwasaki Y, Sakaguchi K, Taguchi T, Nishiyama M, Nigawara T, Kambayashi M, Sawada T, Jing X, Miyajima M, Terada Y, Hashimoto K, Suda T. Involvement of GCMB in the transcriptional regulation of the human parathyroid hormone gene in a parathyroid-derived cell line PT-r: effects of calcium and 1,25(OH)2D3. Bone 2010; 47:534-41. [PMID: 20558332 DOI: 10.1016/j.bone.2010.05.031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 03/02/2010] [Accepted: 05/24/2010] [Indexed: 11/26/2022]
Abstract
Expression of the PTH gene is known to be under strict tissue-specific control and is also regulated by extracellular calcium and 1,25(OH)(2)D. However, the precise mode of transcriptional regulation remains to be elucidated, because of the unavailability of appropriate cell lines derived from the parathyroid gland. We tried to identify the transcription factor(s) regulating the human PTH gene transcription using the PT-r cell line. We found that PT-r cells endogenously express PTH and several parathyroid-related genes. Using the cells, we investigated the transcriptional regulation of human PTH gene. We found that GCMB binds to the PTH gene 5'-promoter (-390/-383 bp) and positively regulates its transcription. On the other hand, 1,25(OH)(2)D(3), and, in the presence of the calcium sensing receptor, high extracellular calcium, exerted inhibitory effects on PTH gene expression. These results indicate that GCMB and vitamin D receptor are involved in the positive and negative regulation of PTH gene expression, respectively. Our data also suggest that PT-r cells retain some of the characteristics of parathyroid cells.
Collapse
Affiliation(s)
- Masayuki Kawahara
- Department of Endocrinology, Metabolism, and Nephrology, Kochi Medical School, Kochi University, Nankoku 783-8505, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
2
|
Wang D, Canaff L, Davidson D, Corluka A, Liu H, Hendy GN, Henderson JE. Alterations in the sensing and transport of phosphate and calcium by differentiating chondrocytes. J Biol Chem 2001; 276:33995-4005. [PMID: 11404353 DOI: 10.1074/jbc.m007757200] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During endochondral bone formation and fracture healing, cells committed to chondrogenesis undergo a temporally restricted program of differentiation that is characterized by sequential changes in their phenotype and gene expression. This results in the manufacture, remodeling, and mineralization of a cartilage template on which bone is laid down. Articular chondrocytes undergo a similar but restricted differentiation program that does not proceed to mineralization, except in pathologic conditions such as osteoarthritis. The pathogenesis of disorders of cartilage development and metabolism, including osteochondrodysplasia, fracture non-union, and osteoarthritis remain poorly defined. We used the CFK2 model to examine the potential roles of phosphate and calcium ions in the regulatory pathways that mediate chondrogenesis and cartilage maturation. Differentiation was monitored over a 4-week period using a combination of morphological, biochemical, and molecular markers that have been characterized in vivo and in vitro. CFK2 cells expressed the type III sodium-dependent phosphate transporters Glvr-1 and Ram-1, as well as a calcium-sensing mechanism. Regulated expression and activity of Glvr-1 by extracellular phosphate and parathyroid hormone-related protein was restricted to an early stage of CFK2 differentiation, as evidenced by expression of type II collagen, proteoglycan, and Ihh. On the other hand, regulated expression and activity of a calcium-sensing receptor by extracellular calcium was most evident after 2 weeks of differentiation, concomitant with an increase in type X collagen expression, alkaline phosphatase activity and parathyroid hormone/parathyroid hormone-related protein receptor expression. On the basis of these temporally restricted changes in the sensing and transport of phosphate and calcium, we predict that extracellular phosphate plays a role in the commitment of chondrogenic cells to differentiation, whereas extracellular calcium plays a role at a later stage in their differentiation program.
Collapse
Affiliation(s)
- D Wang
- Department of Medicine, McGill University, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital Montréal, Québec, Canada H3T 1E2
| | | | | | | | | | | | | |
Collapse
|
3
|
Lewin E, Almaden Y, Rodriguez M, Olgaard K. PTHrP enhances the secretory response of PTH to a hypocalcemic stimulus in rat parathyroid glands. Kidney Int 2000; 58:71-81. [PMID: 10886551 DOI: 10.1046/j.1523-1755.2000.00142.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND The secretion of parathyroid hormone (PTH) from the parathyroid glands might be regulated by autocrine/paracrine factors, and a feedback regulatory mechanism of PTH on the secretion of PTH has been suggested. Because of the existence of a common receptor between PTH and PTH-related peptide (PTHrP), the aim of the present study was to examine the possible effects of PTHrP 1-40 and 1-86 on PTH secretion in rats. METHODS In vivo, the effect of PTHrP on Ca++-regulated PTH secretion was examined by the induction of hypocalcemia and hypercalcemia by an infusion of EGTA and Ca++, with and without PTHrP. The eventual effects of PTHrP on the peripheral metabolism of PTH were examined by infusion of human PTH (hPTH) with and without PTHrP. hPTH was measured by an intact hPTH assay not cross reacting with rat PTH or PTHrP. To examine whether near physiological levels of circulating PTH have an autoregulatory effect in vivo on PTH secretion from the parathyroid gland, an acute reduction of the circulating PTH was induced by an acute unilateral parathyroidectomy (UPTX). PTH secretion from the remaining parathyroid gland was followed in response to EGTA-induced hypocalcemia. In vitro investigations on the effect of PTHrP 1-40 on PTH secretion from whole rat parathyroid glands incubated in media containing a calcium concentration of 0.6 or 1.35 mmol/L were performed to confirm whether the effect of PTHrP was directly on the gland. The rat PTH assay was examined for cross reaction with PTHrP. RESULTS In vivo, the same rate of decrease of plasma Ca++ was induced in the experimental groups. The maximal response of PTH to hypocalcemia (218 +/- 16 pg/mL, N = 6) was significantly enhanced by PTHrP 1-40 (525 +/- 79 pg/mL, N = 6) and by PTHrP 1-86 (465 +/- 29 pg/mL, N = 6, P < 0.001). No effect of PTHrP on PTH secretion was found during normocalcemia or hypercalcemia. UPTX resulted in a 50% reduction of PTH secretion, and no compensatory increase of PTH was observed. PTHrP had no effect on the metabolism of PTH. In vitro, low-Ca++-induced PTH secretion was significantly augmented by 300% (P < 0.01) when the medium contained PTHrP 1-40. PTHrP did not cross react with the PTH assay. CONCLUSIONS PTHrP significantly enhanced the low-Ca++-stimulated PTH secretion in vivo and in vitro. An autocrine/paracrine role of PTHrP in the parathyroid glands is suggested. An autoregulatory effect of circulating PTH on the PTH secretion from parathyroid glands seems unlikely. The "maximal secretory capacity" of the parathyroid glands induced by hypocalcemia in vivo and in vitro is not the maximum, as PTH secretion can be increased even further, by several-fold.
Collapse
Affiliation(s)
- E Lewin
- Nephrological Department P, Rigshospitalet, University of Copenhagen, Denmark
| | | | | | | |
Collapse
|
4
|
Fujii Y, Tomić M, Stojilković SS, Iida T, Brandi ML, Ogino Y, Sakaguchi K. Effects of endothelin-1 on Ca2+ signaling and secretion in parathyroid cells. J Bone Miner Res 1995; 10:716-25. [PMID: 7639107 DOI: 10.1002/jbmr.5650100508] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
It has been previously reported that parathyroid cells express endothelin (ET) receptors and secrete ET-1 in an extracellular Ca2+ concentration ([Ca2+]e)-dependent manner. Here, we examined the effects of ET-1 on intracellular signaling and parathyroid hormone (PTH) secretion in dispersed bovine parathyroid (bPT) cells, which comprise several cell types including epithelial and endothelial cells, in two cell lines, the rat parathyroid epithelial (PT-r) and the bovine parathyroid endothelial (BPE-1) cells. An RNA-polymerase chain reaction analysis revealed that both ETA and ETB receptors are expressed in bovine parathyroid tissue and BPE-1 cells, and only the ETA receptor is expressed in PT-r cells. PT-r cells also expressed an inositol 1,4,5-trisphosphate (Ins[1,4,5]P3) receptor, and ionomycin induced an increase in the intracellular Ca2+ concentrations ([Ca2+]i) in a Ca(2+)-deficient medium, indicating the presence of an operative intracellular Ca2+ pool in these cells. In cells bathed in 1 mM [Ca2+]e, ET-1 induced a rapid and transient increase in the Ins(1,4,5)P3 production, which was associated with a similar profile of increase in [Ca2+]i and with a peak response of about 800 nM. No changes in the profile of [Ca2+]i responses were observed in ET-1-stimulated cells in the presence of Ca2+ channel blockers, or in Ca(2+)-deficient medium, indicating that Ca2+ mobilization was not associated with Ca2+ entry. Furthermore, a sustained stimulation with ET-1 induced a decrease in [Ca2+]i below the prestimulatory level in a large population of cells, and the percentage of the cell population that shows the sustained decrease of [Ca2+]i increased in higher ET-1 concentrations. [Ca2+]i in PT-r cells was also controlled by a [Ca2+]e-dependent mechanism that changed [Ca2+]i from 28 to 506 nM in a 0.1-3 mM concentration range with an EC50 of 1.2 mM, which is comparable to that reported for bPT cells. In the same range of [Ca2+]e, PTH secretion from bPT cells was inhibited with an IC50 of 1 mM, and ET-1 increased PTH release in a dose-dependent manner but without affecting the IC50 for the [Ca2+]e-dependent inhibition. Thus, the parathyroid epithelial cells appear to respond to ET-1 in a unique way, and the ET autocrine system can be regarded as a possible mechanism to modulate the sensitivity of [Ca2+]e-dependent PTH release.
Collapse
Affiliation(s)
- Y Fujii
- Metabolic Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | | | | | | | | | | | | |
Collapse
|
5
|
Axiotis CA, Bani D, Bianchi S, Pioli P, Tanini A, Brandi ML. P-glycoprotein is expressed in parathyroid epithelium and is regulated by calcium. Calcif Tissue Int 1995; 56:170-4. [PMID: 7736328 DOI: 10.1007/bf00296351] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
P-glycoprotein (Pgp), the multidrug resistance (mdr) gene product, has been described in normal tissues with diverse physiologic functions. A broad role as a transporter protein for toxins, hormones, and physiologic metabolites has been provisionally deduced, based on structural analysis and immunoanatomic localization. Recently, significant levels of Pgp have been demonstrated in endocrine and hormonally responsive tissues and tumors. We examined calcium-regulated, clonal parathyroid epithelial (PT-r) and endothelial cells (BPE-1) and frozen parathyroid tissue from normal human parathyroid, parathyroid hyperplasia, parathyroid adenoma, and parathyroid carcinoma for expression of the multidrug resistance gene (Mdr1) and Pgp utilizing Northern and Western analysis and immunohistochemistry. We also investigated the effect of extracellular calcium (eCa) on Pgp expression in PT-r cells at the molecular/cellular level. Immunohistochemistry, utilizing three murine monoclonal antibodies (MAbs)--C494, JSB-1, and C219--which recognize spatially distinct cytoplasmic epitopes of Pgp, revealed strong immunoreactivity in PT-r cells, normal parathyroid, and parathyroid hyperplasia, and weak immunostaining in parathyroid adenomas. BPE-1 cells, endothelial cells, and parathyroid carcinoma were negative. PT-r cells showed a single 130 kDa band (120 KDa after glycosidase treatment) on Western blot and a 4.6 kb transcript on Northern analysis, consistent with Pgp. Western and Northern blot analysis of PTr cells cultured in different eCa concentrations showed that eCa up-regulated Pgp expression.
Collapse
Affiliation(s)
- C A Axiotis
- Department of Pathology, State University of New York Health Science Center at Brooklyn, Kings County Hospital Center, Brooklyn 11203
| | | | | | | | | | | |
Collapse
|
6
|
Abstract
We review the current state of knowledge of the molecular properties and actions of parathyroid hormone-related protein (PTHrP) both in cancer patients and in normal physiology. PTHrP is a common product of squamous cancers and is the major mediator of the syndrome of humoral hypercalcemia of malignancy (HHM) by its actions through parathyroid hormone receptors in bone and kidney. Recently developed radioimmunoassays and tissue localization techniques indicate that PTHrP is produced by many more cancers than was originally indicated by clinical studies and that it contributes significantly to malignancy-related hypercalcemia associated with other etiologies, for example, cancers metastatic to bone and hematological malignancies. The gene encoding PTHrP is complex, with multiple exons coding for up to 12 alternate transcripts and three different length proteins, potentially in a tissue-specific manner, by the use of three promoters. Its expression is regulated by hormones and growth factors, and the untranslated exons display features in common with many cytokine genes. Although potential endocrine actions of PTHrP are evident in fetal development, further evidence suggesting that the normal physiological role of PTHrP is predominantly as a locally produced regulator/cytokine comes from localization studies and investigations of its actions in a variety of tissues. Such studies indicate that in addition to its parathyroid hormone-like actions, PTHrP has multiple activities, including those in fetal development, placental calcium transfer, lactation, smooth muscle relaxation, and on epithelial cell growth. Although PTHrP was discovered because of its production by cancers, evidence for its actions as a local regulator highlights the importance of understanding its roles not only in the etiology of HHM in cancer patients but also in normal tissues.
Collapse
Affiliation(s)
- J M Moseley
- St. Vincent's Institute of Medical Research, St. Vincent's Hospital, Fitzroy, Australia
| | | |
Collapse
|
7
|
Emly JF, Hughes S, Green E, Ratcliffe WA. Expression and secretion of parathyroid hormone-related protein by a human cancer cell line. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1220:193-8. [PMID: 8312363 DOI: 10.1016/0167-4889(94)90135-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The regulation of expression of parathyroid hormone-related protein (PTHRP) mRNA by protein kinase C and cyclic-AMP-dependent pathways was studied in a human lung cancer cell line (BEN). PTHRP mRNA was increased by agents which activate protein kinase C, but not by those which activate cyclic-AMP-dependent pathways. Activators of both second messenger pathways stimulated a dose-dependent increase in the accumulation of PTHRP in conditioned medium assayed using sensitive region-specific immunoassays for PTHRP1-34 and 1-86. Calcitonin had a dose-dependent effect on the accumulation of PTHRP in culture medium which may be mediated via cyclic AMP. Varying the calcium concentration from 0-2.5 mM had no effect on peptide secretion over 20 h, while short-term incubation (30 min) with ionomycin (2.5-75 micrograms/ml) significantly increased PTHRP immunoreactivity in the medium.
Collapse
Affiliation(s)
- J F Emly
- Wolfson Research Laboratories, Department of Clinical Chemistry, Queen Elizabeth Medical Centre, Edgbaston, Birmingham, UK
| | | | | | | |
Collapse
|
8
|
Turzynski A, Baumgart S, Bauch B, Dietel M. Morphological characteristics of tumors with humoral hypercalcemia of malignancy: functional morphology of PTHrP. Recent Results Cancer Res 1994; 137:76-97. [PMID: 7878296 DOI: 10.1007/978-3-642-85073-8_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- A Turzynski
- Institute of Pathology, University Hospital Charité, Humboldt University, Berlin, Germany
| | | | | | | |
Collapse
|
9
|
Connor C, Drees B, Hamilton J. Parathyroid hormone-like peptide and parathyroid hormone are secreted from bovine parathyroid via different pathways. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1178:81-6. [PMID: 8392380 DOI: 10.1016/0167-4889(93)90112-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Parathyroid hormone-like peptide is a recently discovered protein which is thought to be responsible for the hypercalcemia of malignancy. Through the use of radioimmunoassay, Northern analysis and Western blot techniques this protein has been demonstrated to occur in a variety of tumor and normal cells. Its role in normal physiology is not established nor is there knowledge regarding its synthesis, secretion, and storage. We have investigated characteristics of the secretion of parathyroid hormone-like peptide in bovine parathyroid gland slices and cells to learn whether or not this protein is secreted in a manner similar to that of parathyroid hormone. We have used radioimmunoassays specific for PTH and PTH-rP to measure the secretion of each protein and have found that, unlike PTH, PTH-rP secretion was not influenced by the medium calcium concentration. Similarly, PTH-rP secretion was not influenced by other known PTH secretagogues such as c-AMP or isoproterenol. An examination of the subcellular distribution of PTH-rP revealed that 75-90% of it occurs in the soluble fraction of cell lysates. Analysis of isolated secretory granules demonstrated the presence of PTH while PTH-rP was undetectable in these organelles. We conclude that PTH-rP is not secreted from parathyroid cells via the regulated pathway utilizing PTH secretory granules.
Collapse
Affiliation(s)
- C Connor
- Department of Veterans Affairs Medical Centers, Leavenworth, KS
| | | | | |
Collapse
|
10
|
Iguchi H, Katakami H, Ichinose Y, Nishi Y, Tanaka S, Hara N, Ohta M, Haji M, Nawata H. A case of squamous cell lung carcinoma with high concentration of parathyroid hormone-related peptide in serum and pleural effusion presenting hypercalcemia. Jpn J Cancer Res 1993; 84:419-24. [PMID: 8514608 PMCID: PMC5919308 DOI: 10.1111/j.1349-7006.1993.tb00152.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
A 57-year-old man with lung squamous cell carcinoma revealed hypercalcemia, hypophosphoremia, elevation of nephrogenous cAMP and metabolic alkalosis. Serum parathyroid hormone (PTH) and 1,25(OH)2D3 concentrations were not elevated. These findings were consistent with those in humoral hypercalcemia of malignancy (HHM). PTH-related peptide (PTHrP) concentrations were determined using N- and C-terminal specific radioimmunoassays (PTHrP-N, PTHrP-C), and elevation of both PTHrP-N and PTHrP-C concentrations in the serum was noted (PTHrP-N, 27 pmol/liter (normal < 5); PTHrP-C, 1408 pmol/liter (normal < 50)). High concentration of PTHrP (946 pmol/liter for PTHrP-N and 5983 pmol/liter for PTHrP-C) was also found in the pleural fluid obtained at autopsy. Immunohistochemical study, using paraffin-embedded sections of the tumor tissue obtained at autopsy, revealed numerous PTHrP-positive cells and expression of PTHrP gene was confirmed by Northern blot analysis. These findings indicate that PTHrP, produced in the tumor tissue, was secreted into the blood stream, which caused HHM in the patient. Gel permeation chromatography of the serum and pleural fluid revealed several peaks of both PTHrP-N and PTHrP-C. Molecular forms of PTHrP-N were larger than those of PTHrP-C in the serum as well as pleural fluid. These findings indicate that multiple forms of PTHrP molecules are present in the serum and pleural fluid. Granulocytosis was also noted in the patient. However, granulocyte- and granulocyte macrophage-colony stimulating factor were not detected in the serum, and the mechanism of the granulocytosis in the patient was unclear.
Collapse
Affiliation(s)
- H Iguchi
- Department of Biochemistry, National Kyushu Cancer Center, Fukuoka
| | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Brandi ML. Cellular models for the analysis of paracrine communications in parathyroid tissue. J Endocrinol Invest 1993; 16:303-14. [PMID: 8514988 DOI: 10.1007/bf03348842] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- M L Brandi
- Department of Clinical Physiopathology, University of Florence, Medical School, Italy
| |
Collapse
|
12
|
Sakaguchi K. Acidic fibroblast growth factor autocrine system as a mediator of calcium-regulated parathyroid cell growth. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)35800-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
|
13
|
Takeuchi Y, Yanagishita M, Hascall VC. Effects of MgCl2 on the release and recycling of heparan sulfate proteoglycans in a rat parathyroid cell line. Arch Biochem Biophys 1992; 298:371-9. [PMID: 1416969 DOI: 10.1016/0003-9861(92)90424-u] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Divalent cations, such as Mg2+, Ba2+, and Co2+, are known to mimic the effects of Ca2+ in parathyroid cells, but it is not clear whether the mechanism of their action is the same as that of Ca2+. We have shown that extracellular Ca2+ concentration ([Ca2+]e) regulates the distribution and recycling of cell-surface heparan sulfate (HS) proteoglycans in a rat parathyroid cell line; at normal to high [Ca2+]e (e.g., 2 mM) HS proteoglycans are primarily localized intracellularly, while at low [Ca2+]e (0.05 mM) they are translocated to the cell surface and rapidly recycle (Takeuchi, Y., Sakaguchi, K., Yanagishita, M., Aurbach, G. D., and Hascall, V. C., 1990, J. Biol. Chem. 265, 13661-13668). We now show that a high concentration of Mg2+ (8 mM) reduces the amount of recycling HS proteoglycans in low [Ca2+]e. However, the primary effects of high Ca2+ and high Mg2+ on the recycling HS proteoglycans are different. High [Ca2+]e causes translocation of HS proteoglycans to intracellular compartments, while high Mg2+ stimulates cleavage of their core proteins and subsequent shedding of HS proteoglycans into the medium, thereby depleting the recycling molecules. However, high Mg2+ does not induce shedding of HS proteoglycans in high [Ca2+]e. The effects of Ba2+ and Co2+ were similar to those of Mg2+, but Sr2+ showed no significant effects on HS proteoglycan translocation. Otherwise, 8 mM Mg2+ did not alter biosynthesis or intracellular catabolism of HS proteoglycans. These observations suggest that the recycling of HS proteoglycans in parathyroid cells is sensitive only to [Ca2+]e, whereas several other divalent cations can deplete the recycling HS proteoglycans by a distinctly different mechanism. Thus, the mechanism by which Ca2+ regulates the amounts of the recycling HS proteoglycans may be more physiological and play a functional role in parathyroid cells.
Collapse
Affiliation(s)
- Y Takeuchi
- Bone Research Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892
| | | | | |
Collapse
|
14
|
Emly JF, Ratcliffe WA, Green E, Bowden SJ, Heath DA, Blight A, Hughes S, Ratcliffe JG. Immunochemical characterisation of parathyroid hormone-related protein from tumour and non-tumour cells. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1180:58-64. [PMID: 1390945 DOI: 10.1016/0925-4439(92)90027-k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The molecular forms of parathyroid hormone-related protein (PTHRP) in conditioned media from the BEN human lung cancer cell line, rat parathyroid cells (PT-r) and human keratinocytes were studied by gel-filtration chromatography with assay of PTHRP by immunoassays and bioassay. Immunoreactivity (1-86 and 1-34) and bioactivity (1-34) in conditioned media eluted as a coincident major peak (approx. molecular mass 19-22 kDa) and there was evidence of amino-terminal species in the molecular mass range 10-16 kDa in BEN and keratinocyte media. Western blotting of PTHRP affinity purified by monoclonal antibodies directed at regions 1-34 or 37-67, identified a major species in all cell cytosols and media with an apparent molecular mass of 24-25 kDa, consistently slightly larger than recombinant PTHRP(1-141) (mobility of 21 kDa) which may represent an intact or native form of PTHRP. Additional amino-terminal species were identified in medium from keratinocytes (16 and 7 kDa), BEN cells (18 and 14 kDa) and PT-R cells (17 kDa), suggesting that processing occurs at the C-terminus and within the mid-region to form a range of amino-terminal fragments.
Collapse
Affiliation(s)
- J F Emly
- Wolfson Research Laboratories, Department of Clinical Chemistry, Queen Elizabeth Medical Centre, Birmingham, UK
| | | | | | | | | | | | | | | |
Collapse
|
15
|
De Feo ML, Bartolini O, Orlando C, Maggi M, Serio M, Pines M, Hurwitz S, Fujii Y, Sakaguchi K, Aurbach GD. Natriuretic peptide receptors regulate endothelin synthesis and release from parathyroid cells. Proc Natl Acad Sci U S A 1991; 88:6496-500. [PMID: 1650471 PMCID: PMC52112 DOI: 10.1073/pnas.88.15.6496] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Cloned rat parathyroid cells (PTr cell line) that produce parathyroid hormone-related peptide plus endothelin 1 and primary cultures of human parathyroid cells were tested for growth and differentiation responses to atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). High- and low-affinity binding sites for ANP were found on PTr cells; BNP appeared to bind to the same receptors with similar affinities. Either ANP or BNP stimulated production of cGMP and caused a 30% decrease in Na(+)-K(+)-Cl- cotransport. Each peptide increased synthesis and secretion of endothelin 1 by PTr cells in a dose-dependent fashion, but cell growth was not affected. Human parathyroid cells (normal and pathological) also responded to ANP or BNP with an increase in cGMP production. The finding of receptors for natriuretic hormones on parathyroid cells with consequent effects on release of endothelin 1 might be of relevance in understanding the clinical association between hyperparathyroidism and hypertension.
Collapse
Affiliation(s)
- M L De Feo
- Department of Clinical Physiopathology, University of Florence, Italy
| | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Martin TJ, Moseley JM, Gillespie MT. Parathyroid hormone-related protein: biochemistry and molecular biology. Crit Rev Biochem Mol Biol 1991; 26:377-95. [PMID: 1935171 DOI: 10.3109/10409239109114073] [Citation(s) in RCA: 141] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
This article critically reviews the current state of knowledge regarding the recently identified and cloned novel hormone parathyroid hormone-related protein (PTHrP). PTHrP is produced by tumors associated with the syndrome of humoral hypercalcemia of malignancy giving rise to the parathyroid hormone (PTH)-like symptoms characteristic of the syndrome. Areas that will be reviewed include identification, purification and cloning, localization, actions, and significance of PTHrP in cancers and normal physiology. The structure and regulation of the PTHrP gene that may be ancestrally related to the PTH gene will also be discussed. Studies in vivo and in vitro with synthetic and recombinant PTHrP sequences and antibodies developed against them have established that the PTH-like actions of PTHrP are mediated via the N-terminal sequences, which show some limited sequence homology with PTH. Evidence for PTH and non-PTH-like actions of PTHrP in normal physiology, which implicate a role for PTHrP in fetal and neonatal development, is also presented.
Collapse
Affiliation(s)
- T J Martin
- University of Melbourne, Department of Medicine, Australia
| | | | | |
Collapse
|
17
|
Mangin M, Ikeda K, Broadus AE. Structure of the mouse gene encoding parathyroid hormone-related peptide. Gene X 1990; 95:195-202. [PMID: 2249778 DOI: 10.1016/0378-1119(90)90362-u] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The parathyroid hormone-related peptide (PTHRP) was initially isolated from tumors associated with the syndrome of humoral hypercalcemia of malignancy. The human PTHRP gene is a complex transcriptional unit which uses multiple promoters and contains alternatively spliced 3' exons that result in mRNAs encoding three different deduced products. We report here the structure of the mouse PTHRP gene. The mouse gene has a considerably simpler organization than its human counterpart. This organization includes a single 3' exon and an apparent single 3' splicing pathway, leading to an mRNA encoding a 139-amino acid mature PTHRP. In addition, the mouse gene appears to be predominantly under the control of a short proximal promoter element. By RNase protection analysis, we identified PTHRP mRNA in specimens prepared from a variety of normal rodent tissues, including a number of tissues not previously recognized as sites of PTHRP gene expression.
Collapse
Affiliation(s)
- M Mangin
- Department of Internal Medicine, Yale University, New Haven, CT 06510
| | | | | |
Collapse
|
18
|
Sakaguchi K, Ikeda K, Curcio F, Aurbach GD, Brandi ML. Subclones of a rat parathyroid cell line (PT-r): regulation of growth and production of parathyroid hormone-related peptide (PTHRP). J Bone Miner Res 1990; 5:863-9. [PMID: 1700579 DOI: 10.1002/jbmr.5650050810] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Four subclones from a rat parathyroid cell line (PT-r cell) have been isolated, and morphological and functional characteristics have been examined. Subclones 1 and 2 display a polygonal shape, show growth and secretory responses to calcium (half-maximal suppressions at 1.2 and 1.7 mM, respectively), and respond to secretin with cAMP production (14.5-fold and 16.9-fold over basal) and hormone secretion (41 and 58% over basal). Subclone 4 is elongated in form and does not respond to calcium or secretin. Subclone 3 shows mixed morphology, elongated and polygonal shapes, with moderate response to calcium (half-maximal suppression at 1.7 mM) and secretin (cAMP, 3.2-fold increase and hormone secretion, 50% increase over basal). The clones were tested for content of messenger RNA (mRNA) representing parathyroid hormone (PTH) and parathyroid hormone-related peptide (PTHRP). Only PTHRP mRNA was found. The peptide released is virtually all PTHRP. PTH mRNA was not detected even with a sensitive RNA probe. The amount of mRNA for PTHRP closely paralleled the amount of PTH-like bioactivity released into the medium from each clone (144.7 +/- 12.1, 110.0 +/- 12.9, 68.0 +/- 5.6, and 39.9 +/- 2.4 pgEq of rat PTH-(-34) per 10(7) cells per 12 h in a medium with 0.7 mM ionized calcium, from subclones 1, 2, 3, and 4, respectively). Culture conditions, low-density passage (less than 1:50 split ratio) or high-density passage (greater than 1:10 split ratio), affected morphology and function of the clones 1 and 2. They became elongated and functionally dedifferentiated like subclone 4 and 3 months of high-density culture.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- K Sakaguchi
- Metabolic Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| | | | | | | | | |
Collapse
|
19
|
Extracellular calcium regulates distribution and transport of heparan sulfate proteoglycans in a rat parathyroid cell line. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)77400-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
20
|
Ikeda K, Lu C, Weir EC, Mangin M, Broadus AE. Regulation of parathyroid hormone-related peptide gene expression by cycloheximide. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)39372-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
|
21
|
Caulfield MP, McKee RL, Goldman ME, Thiede MA, Thompson DD, Fisher JE, Levy JJ, Seedor JG, Horiuchi N, Clemens TL. Parathyroid hormone-related protein (PTHrP): studies with synthetic peptides indicate that parathyroid hormone and PTHrP interact with the same receptor. INTERNATIONAL JOURNAL OF RADIATION APPLICATIONS AND INSTRUMENTATION. PART B, NUCLEAR MEDICINE AND BIOLOGY 1990; 17:633-7. [PMID: 2175735 DOI: 10.1016/0883-2897(90)90076-d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- M P Caulfield
- Merck Sharp and Dohme Research Laboratories, West Point, PA 19486
| | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Zajac JD, Callaghan J, Eldridge C, Diefenbach-Jagger H, Suva LJ, Hudson P, Moseley JM, Michelangeli VP, Pasquini G. Production of parathyroid hormone-related protein by a rat parathyroid cell line. Mol Cell Endocrinol 1989; 67:107-12. [PMID: 2612735 DOI: 10.1016/0303-7207(89)90236-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Parathyroid hormone-related protein (PTHrP), the peptide associated with humoral hypercalcemia of malignancy, has been identified in fetal and adult parathyroid glands. We here report a sub-clone of a rat parathyroid cell line which secretes a single peptide species corresponding in size to PTHrP(1-84). Biological activity of the secretion product was blocked by a specific antiserum against PTHrP, but not by parathyroid hormone (PTH) antiserum. Secretion of PTHrP by these cells was regulated by extracellular calcium in the physiological range. A single messenger RNA species for PTHrP was identified, though PTH mRNA could not be shown in these cells. Hybrid CAT genes containing 700-1000 bp of 5'-flanking DNA from the human PTH or PTHrP genes were transfected into these cells, and the PTHrP gene was expressed at 10-fold higher levels than the PTH gene. These cells thus provide a valuable model system for investigation expression of PTHrP in a non-transformed cell line.
Collapse
Affiliation(s)
- J D Zajac
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Victoria, Australia
| | | | | | | | | | | | | | | | | |
Collapse
|
23
|
|