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Chandran M, Yeh LTL, de Jong MC, Bilezikian JP, Parameswaran R. Cognitive deficits in primary hyperparathyroidism - what we know and what we do not know: A narrative review. Rev Endocr Metab Disord 2022; 23:1079-1087. [PMID: 35994179 DOI: 10.1007/s11154-022-09750-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/04/2022] [Indexed: 10/15/2022]
Abstract
Classic symptoms of primary hyperparathyroidism (PHPT) are seen in approximately 20% of patients. While features such as kidney stones and skeletal disease are often highlighted as directly related to the disease, others can be even more prevalent. For example, cognitive dysfunction and reduced quality of life are common complaints in many patients, even among those who are classified as being asymptomatic. The pathophysiology of PHPT involves the impact of excess parathyroid hormone (PTH) on calcium metabolism. Referencing putative neurocognitive issues, many animal studies have illustrated the potential roles of PTH and PTH receptors in the brain. Functional imaging and pre-and post-parathyroidectomy studies have suggested a link between the neuronal impact of elevated PTH levels on specific functional aspects of the central nervous system, such as cognition. Confounding a direct role for PTH are hypercalcemia and vitamin D deficiency, both of which could conceivably alter CNS function in PHPT. The lack of strong evidence that parathyroidectomy improves cognition in patients with PHPT raises the question as to whether parathyroid surgery should be recommended on this basis alone. This narrative review summarizes the available literature on neurocognitive function in PHPT.
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Affiliation(s)
- Manju Chandran
- Osteoporosis and Bone Metabolism Unit, Department of Endocrinology, Singapore General Hospital, Singapore, Singapore.
- DUKE-NUS Medical School, Singapore, Singapore.
| | - Lydia Tan Li Yeh
- Division of Endocrine Surgery, National University Health System, Singapore, Singapore
| | - Mechteld C de Jong
- Division of Endocrine Surgery, National University Health System, Singapore, Singapore
| | - John P Bilezikian
- Division of Endocrinology, Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA
| | - Rajeev Parameswaran
- Division of Endocrine Surgery, National University Health System, Singapore, Singapore
- Division of Endocrine Surgery, National University Hospital System, Singapore, Singapore
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Sirico A, Dell’Aquila M, Tartaglione L, Moresi S, Farì G, Pitocco D, Arena V, Lanzone A. PTH-rP and PTH-R1 Expression in Placentas from Pregnancies Complicated by Gestational Diabetes: New Insights into the Pathophysiology of Hyperglycemia in Pregnancy. Diagnostics (Basel) 2021; 11:diagnostics11081356. [PMID: 34441291 PMCID: PMC8394866 DOI: 10.3390/diagnostics11081356] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/20/2021] [Accepted: 07/25/2021] [Indexed: 11/30/2022] Open
Abstract
Background: this study investigated the expression of parathyroid hormone-related protein (PTH-rP) and PTH/PTH-rP receptor PTH-R1 in placentas from women with gestational DM (GDM), and the relationship between PTH-R1 and PTH-rP expression and pregnancy characteristics. Methods: we prospectively enrolled 78 pregnant women with GDM, and immunochemistry for PTH-rP and PTH-R1 was performed on placentas. Patients were grouped according to the positivity of PTH-R1 or PTH-rP expression, and pregnancy characteristics were compared between the two groups. Results: PTH-rP and PTH-R1 expression were highest in the extravillous cytotrophoblast and in the decidua. In extravillous cytotrophoblast, PTH-rP expression was higher in women with abnormal at fasting glycemia compared to women with abnormal 60′ or 120′ glycemia (25/25, 50% vs. 6/28, 21.4%, χ2 = 6.12, p = 0.01), and PTH-R1 expression was higher in women with abnormal oral glucose tolerance test (OGTT) at fasting glycemia compared to women with abnormal 60′ or 120′ glycemia (37/50, 74% vs. 15/28, 53.6%, χ2 = 3.37, p = 0.06). In syncytiotrophoblast, PTH-rP-positive placentas were characterized by higher incidence of 1 min Apgar score < 7 (2/9, 22.2% vs. 2/69, 2.9%, χ2 = 6.11, p = 0.01) and maternal obesity (4/9, 44.4% vs. 11/69, 16.7%, χ2 = 3.81, p = 0.05). Conclusion: placental PTH-rP and PTH-R1 expression is dependent on the type of maternal hyperglycemia, and it is associated with adverse pregnancy outcomes.
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Affiliation(s)
- Angelo Sirico
- Obstetrics and High-Risk Pregnancy Unit, Department of Woman, Child Health and Public Health, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli 8, 00168 Rome, Italy; (S.M.); (A.L.)
- Correspondence: ; Tel.: +39-06-30155897
| | - Marco Dell’Aquila
- Pathology Unit, Department of Woman, Child Health and Public Health, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli 8, 00168 Rome, Italy; (M.D.); (V.A.)
| | - Linda Tartaglione
- Diabetology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli 8, 00168 Rome, Italy; (L.T.); (D.P.)
| | - Sascia Moresi
- Obstetrics and High-Risk Pregnancy Unit, Department of Woman, Child Health and Public Health, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli 8, 00168 Rome, Italy; (S.M.); (A.L.)
| | - Giorgia Farì
- Institute of Biochemistry and Clinical Biochemistry, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli 8, 00168 Rome, Italy;
- Faculty of Medicine and Surgery, Università Cattolica del Sacro Cuore, Largo Agostino Gemelli 8, 00168 Rome, Italy
| | - Dario Pitocco
- Diabetology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli 8, 00168 Rome, Italy; (L.T.); (D.P.)
- Faculty of Medicine and Surgery, Università Cattolica del Sacro Cuore, Largo Agostino Gemelli 8, 00168 Rome, Italy
| | - Vincenzo Arena
- Pathology Unit, Department of Woman, Child Health and Public Health, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli 8, 00168 Rome, Italy; (M.D.); (V.A.)
| | - Antonio Lanzone
- Obstetrics and High-Risk Pregnancy Unit, Department of Woman, Child Health and Public Health, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli 8, 00168 Rome, Italy; (S.M.); (A.L.)
- Faculty of Medicine and Surgery, Università Cattolica del Sacro Cuore, Largo Agostino Gemelli 8, 00168 Rome, Italy
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van Gastel J, Leysen H, Boddaert J, Vangenechten L, Luttrell LM, Martin B, Maudsley S. Aging-related modifications to G protein-coupled receptor signaling diversity. Pharmacol Ther 2020; 223:107793. [PMID: 33316288 DOI: 10.1016/j.pharmthera.2020.107793] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 11/26/2020] [Indexed: 02/06/2023]
Abstract
Aging is a highly complex molecular process, affecting nearly all tissue systems in humans and is the highest risk factor in developing neurodegenerative disorders such as Alzheimer's and Parkinson's disease, cardiovascular disease and Type 2 diabetes mellitus. The intense complexity of the aging process creates an incentive to develop more specific drugs that attenuate or even reverse some of the features of premature aging. As our current pharmacopeia is dominated by therapeutics that target members of the G protein-coupled receptor (GPCR) superfamily it may be prudent to search for effective anti-aging therapeutics in this fertile domain. Since the first demonstration of GPCR-based β-arrestin signaling, it has become clear that an enhanced appreciation of GPCR signaling diversity may facilitate the creation of therapeutics with selective signaling activities. Such 'biased' ligand signaling profiles can be effectively investigated using both standard molecular biological techniques as well as high-dimensionality data analyses. Through a more nuanced appreciation of the quantitative nature across the multiple dimensions of signaling bias that drugs possess, researchers may be able to further refine the efficacy of GPCR modulators to impact the complex aberrations that constitute the aging process. Identifying novel effector profiles could expand the effective pharmacopeia and assist in the design of precision medicines. This review discusses potential non-G protein effectors, and specifically their potential therapeutic suitability in aging and age-related disorders.
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Affiliation(s)
- Jaana van Gastel
- Receptor Biology Lab, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium; Faculty of Pharmacy, Biomedical and Veterinary Science, University of Antwerp, Antwerp, Belgium
| | - Hanne Leysen
- Receptor Biology Lab, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium; Faculty of Pharmacy, Biomedical and Veterinary Science, University of Antwerp, Antwerp, Belgium
| | - Jan Boddaert
- Molecular Pathology Group, Faculty of Medicine and Health Sciences, Laboratory of Cell Biology and Histology, Antwerp, Belgium
| | - Laura Vangenechten
- Receptor Biology Lab, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Louis M Luttrell
- Division of Endocrinology, Diabetes & Medical Genetics, Medical University of South Carolina, USA
| | - Bronwen Martin
- Faculty of Pharmacy, Biomedical and Veterinary Science, University of Antwerp, Antwerp, Belgium
| | - Stuart Maudsley
- Receptor Biology Lab, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium; Faculty of Pharmacy, Biomedical and Veterinary Science, University of Antwerp, Antwerp, Belgium.
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Stutz C, Batool F, Petit C, Strub M, Kuchler-Bopp S, Benkirane-Jessel N, Huck O. Influence of parathyroid hormone on periodontal healing in animal models: A systematic review. Arch Oral Biol 2020; 120:104932. [PMID: 33113458 DOI: 10.1016/j.archoralbio.2020.104932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 07/10/2020] [Accepted: 09/21/2020] [Indexed: 12/09/2022]
Abstract
OBJECTIVES The purpose of this systematic review was to determine the potential interest of parathyroid hormone (PTH) as an adjunct to periodontal treatment based on studies performed in rodents. MATERIALS & METHODS Electronic databases (MEDLINE, Web of Science) were searched up to December 2019. Studies assessing the impact of PTH administration in experimental periodontitis in rodents have been identified. RESULTS Amongst the 247 identified articles, 10 met the inclusion criteria and were included in this systematic review. Experimental periodontitis was mainly induced by ligature placement or surgically with a dental bur. All studies considered bone healing after PTH administration at different frequencies as primary outcome. Results showed that an intermittent administration of PTH promoted bone healing and neovascularization. Nevertheless, a decrease of soft tissue inflammation was also observed. CONCLUSION Intermittent administration of PTH appears to enhance significantly periodontal healing and to promote alveolar bone regeneration. However, due to the risk of side effects, the development of scaffolds allowing its local and time-controlled delivery is of importance.
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Affiliation(s)
- Céline Stutz
- INSERM, UMR 1260 'Osteoarticular and Dental Regenerative Nanomedicine', Faculté de Médecine, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Fareeha Batool
- INSERM, UMR 1260 'Osteoarticular and Dental Regenerative Nanomedicine', Faculté de Médecine, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Catherine Petit
- INSERM, UMR 1260 'Osteoarticular and Dental Regenerative Nanomedicine', Faculté de Médecine, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France; Faculté de Chirurgie Dentaire, Université de Strasbourg, Strasbourg, France; Pôle de Médecine et de Chirurgie Bucco-Dentaires, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Marion Strub
- INSERM, UMR 1260 'Osteoarticular and Dental Regenerative Nanomedicine', Faculté de Médecine, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France; Faculté de Chirurgie Dentaire, Université de Strasbourg, Strasbourg, France; Pôle de Médecine et de Chirurgie Bucco-Dentaires, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Sabine Kuchler-Bopp
- INSERM, UMR 1260 'Osteoarticular and Dental Regenerative Nanomedicine', Faculté de Médecine, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Nadia Benkirane-Jessel
- INSERM, UMR 1260 'Osteoarticular and Dental Regenerative Nanomedicine', Faculté de Médecine, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France
| | - Olivier Huck
- INSERM, UMR 1260 'Osteoarticular and Dental Regenerative Nanomedicine', Faculté de Médecine, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France; Faculté de Chirurgie Dentaire, Université de Strasbourg, Strasbourg, France; Pôle de Médecine et de Chirurgie Bucco-Dentaires, Hôpitaux Universitaires de Strasbourg, Strasbourg, France.
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5
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Parathyroid hormone increases CFTR expression and function in Caco-2 intestinal epithelial cells. Biochem Biophys Res Commun 2020; 523:816-821. [DOI: 10.1016/j.bbrc.2019.12.106] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 12/31/2019] [Indexed: 12/29/2022]
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Bushau-Sprinkle A, Barati M, Conklin C, Dupre T, Gagnon KB, Khundmiri SJ, Clark B, Siskind L, Doll MA, Rane M, Brier M, Coventry S, Lederer ED. Loss of the Na +/H + Exchange Regulatory Factor 1 Increases Susceptibility to Cisplatin-Induced Acute Kidney Injury. THE AMERICAN JOURNAL OF PATHOLOGY 2019; 189:1190-1200. [PMID: 30926337 DOI: 10.1016/j.ajpath.2019.02.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 02/12/2019] [Accepted: 02/25/2019] [Indexed: 12/19/2022]
Abstract
Na+/H+ exchange regulatory cofactor (NHERF)-1, a scaffolding protein, anchors multiple membrane proteins in renal proximal tubules. Cultured proximal tubule cells deficient in Nherf1 and proximal tubules from Nherf1-deficient mice exhibit aberrant trafficking. Nherf1-deficient cells also exhibit an altered transcription pattern and worse survival. These observations suggest that NHERF1 loss increases susceptibility to acute kidney injury (AKI). Male and female wild-type C57BL/6J and Nherf1 knockout mice were treated with saline or cisplatin (20 mg/kg dose i.p.) to induce AKI and were euthanized after 72 hours. Blood and urine were collected for assessments of blood urea nitrogen and neutrophil gelatinase-associated lipocalin, respectively. Kidneys were harvested for histology (hematoxylin and eosin, periodic acid-Schiff) and terminal deoxynucleotidyl transferase dUTP nick end labeling assay, Kim1 mRNA assessment, and Western blot analysis for cleaved caspase 3. Cisplatin treatment was associated with significantly greater severity of AKI in knockout compared with wild-type mice, as demonstrated by semiquantitative injury score (2.8 versus 1.89, P < 0.001), blood urea nitrogen (151.8 ± 17.2 mg/dL versus 97.8 ± 10.1 mg/dL, P < 0.05), and neutrophil gelatinase-associated lipocalin urine protein (55.6 ± 21.3 μg/mL versus 2.7 ± 0.53 μg/mL, P < 0.05). Apoptosis markers were significantly increased in cisplatin-treated Nherf1 knockout and wild-type mice compared to respective controls. These data suggest that NHERF1 loss increases susceptibility to AKI.
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Affiliation(s)
| | - Michelle Barati
- Department of Medicine, Division of Nephrology, University of Louisville, Louisville, Kentucky
| | - Caryl Conklin
- Department of Medicine, Division of Nephrology, University of Louisville, Louisville, Kentucky
| | - Tess Dupre
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, Kentucky
| | - Kenneth B Gagnon
- Department of Medicine, Division of Nephrology, University of Louisville, Louisville, Kentucky
| | - Syed J Khundmiri
- Department of Physiology and Biophysics, Howard University, Washington, DC
| | - Barbara Clark
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, Kentucky
| | - Leah Siskind
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, Kentucky
| | - Mark A Doll
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, Kentucky
| | - Madhavi Rane
- Department of Medicine, Division of Nephrology, University of Louisville, Louisville, Kentucky
| | - Michael Brier
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, Kentucky; Department of Medicine, Division of Nephrology, University of Louisville, Louisville, Kentucky
| | - Susan Coventry
- Department of Pathology, University of Louisville, Louisville, Kentucky; Department of Pediatrics, University of Louisville, Louisville, Kentucky
| | - Eleanor D Lederer
- Department of Medicine, Division of Nephrology, University of Louisville, Louisville, Kentucky; Robley Rex VA Medical Center, Louisville, Kentucky.
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Choudhary S, Santone E, Yee SP, Lorenzo J, Adams DJ, Goetjen A, McCarthy MB, Mazzocca AD, Pilbeam C. Continuous PTH in Male Mice Causes Bone Loss Because It Induces Serum Amyloid A. Endocrinology 2018; 159:2759-2776. [PMID: 29757436 PMCID: PMC6692876 DOI: 10.1210/en.2018-00265] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 05/05/2018] [Indexed: 12/12/2022]
Abstract
Increased bone resorption is considered to explain why intermittent PTH is anabolic for bone but continuous PTH is catabolic. However, when cyclooxygenase-2 (COX2) is absent in mice, continuous PTH becomes anabolic without decreased resorption. In murine bone marrow stromal cells (BMSCs), serum amyloid A (SAA)3, induced in the hematopoietic lineage by the combination of COX2-produced prostaglandin and receptor activator of nuclear factor κB ligand (RANKL), suppresses PTH-stimulated osteoblast differentiation. To determine whether SAA3 inhibits the anabolic effects of PTH in vivo, wild-type (WT) and SAA3 knockout (KO) mice were infused with PTH. In WT mice, continuous PTH induced SAA3 and was catabolic for bone. In KO mice, PTH was anabolic, increasing trabecular bone, serum markers of bone formation, and osteogenic gene expression. In contrast, PTH increased all measurements associated with bone resorption, as well as COX2 gene expression, similarly in KO and WT mice. SAA1 and SAA2 in humans are likely to have analogous functions to SAA3 in mice. RANKL induced both SAA1 and SAA2 in human bone marrow macrophages in a COX2-dependent manner. PTH stimulated osteogenesis in human BMSCs only when COX2 or RANKL was inhibited. Addition of recombinant SAA1 or SAA2 blocked PTH-stimulated osteogenesis. In summary, SAA3 suppresses the bone formation responses but not the bone resorption responses to PTH in mice, and in the absence of SAA3, continuous PTH is anabolic. In vitro studies in human bone marrow suggest that SAA may be a target for enhancing the therapeutic effects of PTH in treating osteoporosis.
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Affiliation(s)
- Shilpa Choudhary
- Musculoskeletal Institute, UConn Health, Farmington, Connecticut
- Department of Medicine, UConn Health, Farmington, Connecticut
| | | | - Sui-Pok Yee
- Department of Cell Biology, UConn Health, Farmington, Connecticut
- Center for Mouse Genome Modification, UConn Health, Farmington, Connecticut
| | - Joseph Lorenzo
- Musculoskeletal Institute, UConn Health, Farmington, Connecticut
- Department of Medicine, UConn Health, Farmington, Connecticut
| | - Douglas J Adams
- Musculoskeletal Institute, UConn Health, Farmington, Connecticut
| | | | | | | | - Carol Pilbeam
- Musculoskeletal Institute, UConn Health, Farmington, Connecticut
- Department of Medicine, UConn Health, Farmington, Connecticut
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Madrigal A, Tan L, Zhao Y. Expression regulation and functional analysis of RGS2 and RGS4 in adipogenic and osteogenic differentiation of human mesenchymal stem cells. Biol Res 2017; 50:43. [PMID: 29279050 PMCID: PMC5742872 DOI: 10.1186/s40659-017-0148-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 12/14/2017] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Understanding the molecular basis underlying the formation of bone-forming osteocytes and lipid-storing adipocytes will help provide insights into the cause of disorders originating in stem/progenitor cells and develop therapeutic treatments for bone- or adipose-related diseases. In this study, the role of RGS2 and RGS4, two members of the regulators of G protein signaling (RGS) family, was investigated during adipogenenic and osteogenenic differentiation of human mesenchymal stem cells (hMSCs). RESULTS Expression of RGS2 and RGS4 were found to be inversely regulated during adipogenesis induced by dexamethasone (DEX) and 3-isobutyl-methylxanthine, regardless if insulin was present, with RGS2 up-regulated and RGS4 down-regulated in response to adipogenic induction. RGS2 expression was also up-regulated during osteogenesis at a level similar to that induced by treatment of DEX alone, a shared component of adipogenic and osteogenic differentiation inducing media, but significantly lower than the level induced by adipogenic inducing media. RGS4 expression was down-regulated during the first 48 h of osteogenesis but up-regulated afterwards, in both cases at levels similar to that induced by DEX alone. Expression knock-down using small interfering RNA against RGS2 resulted in decreased differentiation efficiency during both adipogenesis and osteogenesis. On the other hand, expression knock-down of RGS4 also resulted in decreased adipogenic differentiation but increased osteogenic differentiation. CONCLUSIONS RGS2 and RGS4 are differentially regulated during adipogenic and osteogenic differentiation of hMSCs. In addition, both RGS2 and RGS4 play positive roles during adipogenesis but opposing roles during osteogenesis, with RGS2 as a positive regulator and RGS4 as a negative regulator. These results imply that members of RGS proteins may play multifaceted roles during human adipogenesis and osteogenesis to balance or counterbalance each other's function during those processes.
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Affiliation(s)
- Alma Madrigal
- Biological Sciences Department, California State Polytechnic University at Pomona, 3801 W. Temple Ave., Pomona, CA, 91768, USA.,Center for Biomedicine and Genetics, Beckman Research Institute of City of Hope, 1500 E. Duarte Rd., Duarte, CA, 91010, USA
| | - Lun Tan
- Biological Sciences Department, California State Polytechnic University at Pomona, 3801 W. Temple Ave., Pomona, CA, 91768, USA
| | - Yuanxiang Zhao
- Biological Sciences Department, California State Polytechnic University at Pomona, 3801 W. Temple Ave., Pomona, CA, 91768, USA.
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Cyclic AMP Recruits a Discrete Intracellular Ca 2+ Store by Unmasking Hypersensitive IP 3 Receptors. Cell Rep 2017; 18:711-722. [PMID: 28099849 PMCID: PMC5276804 DOI: 10.1016/j.celrep.2016.12.058] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 11/17/2016] [Accepted: 12/19/2016] [Indexed: 12/12/2022] Open
Abstract
Inositol 1,4,5-trisphosphate (IP3) stimulates Ca2+ release from the endoplasmic reticulum (ER), and the response is potentiated by 3′,5′-cyclic AMP (cAMP). We investigated this interaction in HEK293 cells using carbachol and parathyroid hormone (PTH) to stimulate formation of IP3 and cAMP, respectively. PTH alone had no effect on the cytosolic Ca2+ concentration, but it potentiated the Ca2+ signals evoked by carbachol. Surprisingly, however, the intracellular Ca2+ stores that respond to carbachol alone could be both emptied and refilled without affecting the subsequent response to PTH. We provide evidence that PTH unmasks high-affinity IP3 receptors within a discrete Ca2+ store. We conclude that Ca2+ stores within the ER that dynamically exchange Ca2+ with the cytosol maintain a functional independence that allows one store to be released by carbachol and another to be released by carbachol with PTH. Compartmentalization of ER Ca2+ stores adds versatility to IP3-evoked Ca2+ signals. Cyclic AMP directly potentiates IP3-evoked Ca2+ release The Ca2+ stores released by IP3 alone or IP3 with cAMP are functionally independent Cyclic AMP unmasks high-affinity IP3 receptors in a discrete ER Ca2+ store Independent regulation of discrete Ca2+ stores increases signaling versatility
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van Goor MK, Verkaart S, van Dam TJ, Huynen MA, van der Wijst J. Interspecies differences in PTH-mediated PKA phosphorylation of the epithelial calcium channel TRPV5. Pflugers Arch 2017; 469:1301-1311. [PMID: 28534087 PMCID: PMC5590029 DOI: 10.1007/s00424-017-1996-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 05/01/2017] [Accepted: 05/10/2017] [Indexed: 11/26/2022]
Abstract
The epithelial calcium (Ca2+) channel TRPV5 (transient receptor potential vanilloid 5) is expressed in the distal convoluted tubule of the kidney and facilitates active Ca2+ reabsorption. This process is instrumental for the maintenance of Ca2+ homeostasis. Therefore, all aspects of TRPV5 function are tightly regulated by the calciotropic parathyroid hormone (PTH). Rabbit (rb)TRPV5 channel activity was shown to be stimulated upon PTH-mediated protein kinase A (PKA) phosphorylation. Since there is incomplete conservation of the PKA consensus motif (RR/QxT) across species, the aim of this study was to extend these findings to humans and characterize the expression and function of human (h)TRPV5. Functional differences between rbTRPV5 and hTRPV5 upon PTH stimulation were investigated using 45Ca2+ uptake assays, Fura-2 Ca2+ imaging, and cell surface biotinylation. While PTH treatment enhanced rbTRPV5 channel activity, it did not stimulate hTRPV5 activity. Mutation of the human RQxT motif into rabbit RRxT (hTRPV5 Q706R) partially restored the sensitivity to PTH. An ancestral sequence reconstruction of TRPV5 orthologues demonstrated that the change in the RRxT motif coincides with the creation of another putative PKA motif (RGAS to RRAS) in the amino terminus of hTRPV5. Interestingly, a constitutively phosphorylated hTRPV5 mutant (hTRPV5 S141D) displayed significantly decreased channel function, while its plasma membrane abundance was increased. Taken together, PTH-mediated stimulation of TRPV5, via PKA, is not conserved in humans. Our data suggest that PTH regulation of TRPV5 is altered in humans, an important observation for future studies that may add to new concepts on the role of PTH in renal Ca2+ handling.
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Affiliation(s)
- Mark K van Goor
- Department of Physiology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Sjoerd Verkaart
- Department of Physiology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Teunis J van Dam
- Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Theoretical Biology and Bioinformatics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Martijn A Huynen
- Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jenny van der Wijst
- Department of Physiology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
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Jantarajit W, Lertsuwan K, Teerapornpuntakit J, Krishnamra N, Charoenphandhu N. CFTR-mediated anion secretion across intestinal epithelium-like Caco-2 monolayer under PTH stimulation is dependent on intermediate conductance K + channels. Am J Physiol Cell Physiol 2017; 313:C118-C129. [PMID: 28490422 DOI: 10.1152/ajpcell.00010.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 05/02/2017] [Accepted: 05/08/2017] [Indexed: 12/16/2022]
Abstract
Parathyroid hormone (PTH), a pleiotropic hormone that maintains mineral homeostasis, is also essential for controlling pH balance and ion transport across renal and intestinal epithelia. Optimization of luminal pH is important for absorption of trace elements, e.g., calcium and phosphorus. We have previously demonstrated that PTH rapidly stimulated electrogenic [Formula: see text] secretion in intestinal epithelial-like Caco-2 monolayers, but the underlying cellular mechanism, contributions of other ions, particularly Cl- and K+, and long-lasting responses are not completely understood. Herein, PTH and forskolin were confirmed to induce anion secretion, which peaked within 1-3 min (early phase), followed by an abrupt decay and plateau that lasted for 60 min (late phase). In both early and late phases, apical membrane capacitance was increased with a decrease in basolateral capacitance after PTH or forskolin exposure. PTH also induced a transient increase in apical conductance with a long-lasting decrease in basolateral conductance. Anion secretion in both phases was reduced under [Formula: see text]-free and/or Cl--free conditions or after exposure to carbonic anhydrase inhibitor (acetazolamide), CFTR inhibitor (CFTRinh-172), Na+/H+ exchanger (NHE)-3 inhibitor (tenapanor), or K+ channel inhibitors (BaCl2, clotrimazole, and TRAM-34; basolateral side), the latter of which suggested that PTH action was dependent on basolateral K+ recycling. Furthermore, early- and late-phase responses to PTH were diminished by inhibitors of PI3K (wortmannin and LY-294002) and PKA (PKI 14-22). In conclusion, PTH requires NHE3 and basolateral K+ channels to induce [Formula: see text] and Cl- secretion, thus explaining how PTH regulated luminal pH balance and pH-dependent absorption of trace minerals.
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Affiliation(s)
- Walailak Jantarajit
- Center of Calcium and Bone Research, Faculty of Science, Mahidol University, Bangkok, Thailand.,Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Kornkamon Lertsuwan
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand; and
| | | | - Nateetip Krishnamra
- Center of Calcium and Bone Research, Faculty of Science, Mahidol University, Bangkok, Thailand.,Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Narattaphol Charoenphandhu
- Center of Calcium and Bone Research, Faculty of Science, Mahidol University, Bangkok, Thailand; .,Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand.,Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand
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12
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Affiliation(s)
- Morri E Markowitz
- Department of Pediatrics, Albert Einstein College of Medicine, Bronx, NY
| | - Lisa Underland
- Department of Pediatrics, Albert Einstein College of Medicine, Bronx, NY
| | - Robert Gensure
- Department of Pediatrics, Albert Einstein College of Medicine, Bronx, NY
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13
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PTH1R Mutants Found in Patients with Primary Failure of Tooth Eruption Disrupt G-Protein Signaling. PLoS One 2016; 11:e0167033. [PMID: 27898723 PMCID: PMC5127517 DOI: 10.1371/journal.pone.0167033] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Accepted: 11/08/2016] [Indexed: 11/19/2022] Open
Abstract
AIM Primary failure of tooth eruption (PFE) is causally linked to heterozygous mutations of the parathyroid hormone receptor (PTH1R) gene. The mutants described so far lead to exchange of amino acids or truncation of the protein that may result in structural changes of the expressed PTH1R. However, functional effects of these mutations have not been investigated yet. MATERIALS AND METHODS In HEK293 cells, PTH1R wild type was co-transfected with selected PTH1R mutants identified in patients with PFE. The effects on activation of PTH-regulated intracellular signaling pathways were analyzed by ELISA and Western immunoblotting. Differential effects of wild type and mutated PTH1R on TRESK ion channel regulation were analyzed by electrophysiological recordings in Xenopus laevis oocytes. RESULTS In HEK293 cells, activation of PTH1R wild type increases cAMP and in response activates cAMP-stimulated protein kinase as detected by phosphorylation of the vasodilator stimulated phosphoprotein (VASP). In contrast, the PTH1R mutants are functionally inactive and mutant PTH1R/Gly452Glu has a dominant negative effect on the signaling of PTH1R wild type. Confocal imaging revealed that wild type PTH1R is expressed on the cell surface, whereas PTH1R/Gly452Glu mutant is mostly retained inside the cell. Furthermore, in contrast to wild type PTH1R which substantially augmented K+ currents of TRESK channels, coupling of mutated PTH1R to TRESK channels was completely abolished. CONCLUSIONS PTH1R mutations affect intracellular PTH-regulated signaling in vitro. In patients with primary failure of tooth eruption defective signaling of PTH1R mutations is suggested to occur in dento-alveolar cells and thus may lead to impaired tooth movement.
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14
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Walther C, Ferguson SSG. Minireview: Role of intracellular scaffolding proteins in the regulation of endocrine G protein-coupled receptor signaling. Mol Endocrinol 2015; 29:814-30. [PMID: 25942107 DOI: 10.1210/me.2015-1091] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The majority of hormones stimulates and mediates their signal transduction via G protein-coupled receptors (GPCRs). The signal is transmitted into the cell due to the association of the GPCRs with heterotrimeric G proteins, which in turn activates an extensive array of signaling pathways to regulate cell physiology. However, GPCRs also function as scaffolds for the recruitment of a variety of cytoplasmic protein-interacting proteins that bind to both the intracellular face and protein interaction motifs encoded by GPCRs. The structural scaffolding of these proteins allows GPCRs to recruit large functional complexes that serve to modulate both G protein-dependent and -independent cellular signaling pathways and modulate GPCR intracellular trafficking. This review focuses on GPCR interacting PSD95-disc large-zona occludens domain containing scaffolds in the regulation of endocrine receptor signaling as well as their potential role as therapeutic targets for the treatment of endocrinopathies.
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Affiliation(s)
- Cornelia Walther
- J. Allyn Taylor Centre for Cell Biology (C.W., S.S.G.F.), Robarts Research Institute, and Department of Physiology and Pharmacology (S.S.G.F.), University of Western Ontario, London, Ontario, Canada N6A 5K8
| | - Stephen S G Ferguson
- J. Allyn Taylor Centre for Cell Biology (C.W., S.S.G.F.), Robarts Research Institute, and Department of Physiology and Pharmacology (S.S.G.F.), University of Western Ontario, London, Ontario, Canada N6A 5K8
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15
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D. Murray R, D. Lederer E, J. Khundmiri S. Role of PTH in the Renal Handling of Phosphate. AIMS MEDICAL SCIENCE 2015. [DOI: 10.3934/medsci.2015.3.162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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16
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Meena A, Tovey SC, Taylor CW. Sustained signalling by PTH modulates IP3 accumulation and IP3 receptors through cyclic AMP junctions. J Cell Sci 2014; 128:408-20. [PMID: 25431134 PMCID: PMC4294780 DOI: 10.1242/jcs.163071] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Parathyroid hormone (PTH) stimulates adenylyl cyclase through type 1 PTH receptors (PTH1R) and potentiates the Ca2+ signals evoked by carbachol, which stimulates formation of inositol 1,4,5-trisphosphate (IP3). We confirmed that in HEK cells expressing PTH1R, acute stimulation with PTH(1-34) potentiated carbachol-evoked Ca2+ release. This was mediated by locally delivered cyclic AMP (cAMP), but unaffected by inhibition of protein kinase A (PKA), exchange proteins activated by cAMP, cAMP phosphodiesterases (PDEs) or substantial inhibition of adenylyl cyclase. Sustained stimulation with PTH(1-34) causes internalization of PTH1R–adenylyl cyclase signalling complexes, but the consequences for delivery of cAMP to IP3R within cAMP signalling junctions are unknown. Here, we show that sustained stimulation with PTH(1-34) or with PTH analogues that do not evoke receptor internalization reduced the potentiated Ca2+ signals and attenuated carbachol-evoked increases in cytosolic IP3. Similar results were obtained after sustained stimulation with NKH477 to directly activate adenylyl cyclase, or with the membrane-permeant analogue of cAMP, 8-Br-cAMP. These responses were independent of PKA and unaffected by substantial inhibition of adenylyl cyclase. During prolonged stimulation with PTH(1-34), hyperactive cAMP signalling junctions, within which cAMP is delivered directly and at saturating concentrations to its targets, mediate sensitization of IP3R and a more slowly developing inhibition of IP3 accumulation.
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Affiliation(s)
- Abha Meena
- Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD, UK
| | - Stephen C Tovey
- Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD, UK
| | - Colin W Taylor
- Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD, UK
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17
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Wang LL, Chen D, Lee J, Gu X, Alaaeddine G, Li J, Wei L, Yu SP. Mobilization of endogenous bone marrow derived endothelial progenitor cells and therapeutic potential of parathyroid hormone after ischemic stroke in mice. PLoS One 2014; 9:e87284. [PMID: 24503654 PMCID: PMC3913619 DOI: 10.1371/journal.pone.0087284] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 12/20/2013] [Indexed: 12/19/2022] Open
Abstract
Stroke is a major neurovascular disorder threatening human life and health. Very limited clinical treatments are currently available for stroke patients. Stem cell transplantation has shown promising potential as a regenerative treatment after ischemic stroke. The present investigation explores a new concept of mobilizing endogenous stem cells/progenitor cells from the bone marrow using a parathyroid hormone (PTH) therapy after ischemic stroke in adult mice. PTH 1-34 (80 µg/kg, i.p.) was administered 1 hour after focal ischemia and then daily for 6 consecutive days. After 6 days of PTH treatment, there was a significant increase in bone marrow derived CD-34/Fetal liver kinase-1 (Flk-1) positive endothelial progenitor cells (EPCs) in the peripheral blood. PTH treatment significantly increased the expression of trophic/regenerative factors including VEGF, SDF-1, BDNF and Tie-1 in the brain peri-infarct region. Angiogenesis, assessed by co-labeled Glut-1 and BrdU vessels, was significantly increased in PTH-treated ischemic brain compared to vehicle controls. PTH treatment also promoted neuroblast migration from the subventricular zone (SVZ) and increased the number of newly formed neurons in the peri-infarct cortex. PTH-treated mice showed significantly better sensorimotor functional recovery compared to stroke controls. Our data suggests that PTH therapy improves endogenous repair mechanisms after ischemic stroke with functional benefits. Mobilizing endogenous bone marrow-derived stem cells/progenitor cells using PTH and other mobilizers appears an effective and feasible regenerative treatment after ischemic stroke.
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Affiliation(s)
- Li-Li Wang
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, Georgia, United States of America
- Department of Neurology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Dongdong Chen
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Jinhwan Lee
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Xiaohuan Gu
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Ghina Alaaeddine
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Jimei Li
- Department of Neurology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Ling Wei
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, Georgia, United States of America
- Department of Neurology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Shan Ping Yu
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, Georgia, United States of America
- * E-mail:
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18
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Li D, Jiao J, Shatos MA, Hodges RR, Dartt DA. Effect of VIP on intracellular [Ca2+], extracellular regulated kinase 1/2, and secretion in cultured rat conjunctival goblet cells. Invest Ophthalmol Vis Sci 2013; 54:2872-84. [PMID: 23518767 DOI: 10.1167/iovs.12-11264] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
PURPOSE To determine the intracellular signaling pathways that vasoactive intestinal peptide (VIP) uses to stimulate high molecular weight glycoconjugate secretion from cultured rat conjunctival goblet cells. METHODS Goblet cells from rat bulbar and forniceal conjunctiva were grown in organ culture. Presence and localization of VIP receptors (VPAC1 and 2) were determined by RT-PCR, immunofluorescence microscopy and Western blot analysis. Intracellular [Ca(2+)] ([Ca(2+)]i) was measured using fura-2. Extracellular signal-regulated kinase (ERK)-1/2 activity was determined by Western blot analysis. High molecular weight glycoconjugate secretion was measured with an enzyme-linked lectin assay on cultured goblet cells that were serum-starved for 2 hours before stimulation with VIP, VPAC1-, or VPAC2-specific agonists. Inhibitors were added 30 minutes prior to VIP. Activation of epidermal growth factor receptor (EGFR) was measured by immunoprecipitation using an antibody against pTyr followed by Western blot analysis with an antibody against EGFR. RESULTS Both VIP receptors were present in rat conjunctiva and cultured goblet cells. VIP- and VPAC-specific agonists increased [Ca(2+)]i and secretion in a concentration-dependent manner. VIP also increased ERK1/2 activity, VIP-stimulated increase in [Ca(2+)]i. Secretion, but not ERK1/2 activity, was inhibited by the protein kinase A inhibitor, H89. VIP-stimulated secretion was inhibited by siRNA for ERK2 but not by siRNA for EGFR. VIP did not increase the phosphorylation of the EGFR. CONCLUSIONS In conclusion, in cultured rat conjunctival goblet cells, VPAC1 and 2 receptors are functional. VIP stimulates a cAMP-dependent increase in [Ca(2+)]i and glycoconjugate secretion, but not ERK1/2 activation. VIP does not activate with EGFR.
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Affiliation(s)
- Dayu Li
- Schepens Eye Research Institute, Massachusetts Eye and Ear and Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA
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19
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Tovey SC, Taylor CW. Cyclic AMP directs inositol (1,4,5)-trisphosphate-evoked Ca2+ signalling to different intracellular Ca2+ stores. J Cell Sci 2013; 126:2305-13. [PMID: 23525004 DOI: 10.1242/jcs.126144] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Cholesterol depletion reversibly abolishes carbachol-evoked Ca(2+) release from inositol (1,4,5)-trisphosphate (IP3)-sensitive stores, without affecting the distribution of IP3 receptors (IP3R) or endoplasmic reticulum, IP3 formation or responses to photolysis of caged IP3. Receptors that stimulate cAMP formation do not alone evoke Ca(2+) signals, but they potentiate those evoked by carbachol. We show that these potentiated signals are entirely unaffected by cholesterol depletion and that, within individual cells, different IP3-sensitive Ca(2+) stores are released by carbachol alone and by carbachol combined with receptors that stimulate cAMP formation. We suggest that muscarinic acetylcholine receptors in lipid rafts deliver IP3 at high concentration to associated IP3R, stimulating them to release Ca(2+). Muscarinic receptors outside rafts are less closely associated with IP3R and provide insufficient local IP3 to activate IP3R directly. These IP3R, probably type 2 IP3R within a discrete Ca(2+) store, are activated only when their sensitivity is increased by cAMP. Sensitization of IP3R by cAMP extends the effective range of signalling by phospholipase C, allowing muscarinic receptors that are otherwise ineffective to recruit additional IP3-sensitive Ca(2+) stores.
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Affiliation(s)
- Stephen C Tovey
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
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20
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Cupp ME, Nayak SK, Adem AS, Thomsen WJ. Parathyroid hormone (PTH) and PTH-related peptide domains contributing to activation of different PTH receptor-mediated signaling pathways. J Pharmacol Exp Ther 2013; 345:404-18. [PMID: 23516330 DOI: 10.1124/jpet.112.199752] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Parathyroid hormone (PTH) and parathyroid hormone-related peptide (PTHrP), acting through the osteoblast PTH1 receptor (PTH1R), play important roles in bone remodeling. Intermittent administration of PTH(1-34) (teriparatide) leads to bone formation, whereas continuous administration paradoxically leads to bone resorption. Activation of PTH1R promotes regulation of multiple signaling pathways, including G(s)/cAMP/protein kinase A, G(q)/calcium/protein kinase C, β-arrestin recruitment, and extracellular signal-related kinase (ERK)1/2 phosphorylation, as well as receptor internalization, but their role in promoting anabolic and catabolic actions of PTH(1-34) are unclear. In the present investigation, a collection of PTH(1-34) and PTHrP(1-34) peptide analogs were evaluated in orthogonal human PTH1R (hPTH1R) functional assays capturing G(s)- and G(q)-signaling, β-arrestin recruitment, ERK1/2 phosphorylation, and receptor internalization to further define the patterns of PTH1R signaling that they stimulate and further establish peptide domains contributing to agonist activity. Results indicate that both N- and C-terminal domains of PTH and PTHrP are critical for activation of signaling pathways. However, modifications of both regions lead to more substantial decreases in agonist potency and efficacy to stimulate G(q)-signaling, β-arrestin recruitment, ERK1/2 phosphorylation, and receptor internalization than to stimulate G(s)-signaling. The substantial contribution of the peptide C-terminal domain in activation of hPTH1R signaling suggests a role in positioning of the peptide N-terminal region into the receptor J-domain. Several PTH and PTHrP peptides evaluated in this study promote different patterns of biased agonist signaling and may serve as useful tools to further elucidate therapeutically relevant PTH1R signaling in osteoblasts. With a better understanding of therapeutically relevant signaling, novel biased peptides with desired signaling could be designed for safer and more effective treatment of osteoporosis.
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Affiliation(s)
- Meghan E Cupp
- Center for Cancer and Metabolic Diseases, SRI International, 140 Research Drive, Harrisonburg, VA 22802, USA
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21
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Joyce NC, Hache LP, Clemens PR. Bone health and associated metabolic complications in neuromuscular diseases. Phys Med Rehabil Clin N Am 2012; 23:773-99. [PMID: 23137737 DOI: 10.1016/j.pmr.2012.08.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
This article reviews the recent literature regarding bone health as it relates to the patient living with neuromuscular disease (NMD). Studies defining the scope of bone-related disease in NMD are scant. The available evidence is discussed, focusing on abnormal calcium metabolism, increased fracture risk, and the prevalence of both scoliosis and hypovitaminosis D in Duchenne muscular dystrophy, amyotrophic lateral sclerosis, and spinal muscular atrophy. Future directions are discussed, including the urgent need for studies both to determine the nature and extent of poor bone health, and to evaluate the therapeutic effect of available osteoporosis treatments in patients with NMD.
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Affiliation(s)
- Nanette C Joyce
- Department of Rehabilitation Medicine, University of California, Davis, Sacramento, CA 95817, USA.
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