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Tian L, Andrews C, Yan Q, Yang JJ. Molecular regulation of calcium-sensing receptor (CaSR)-mediated signaling. Chronic Dis Transl Med 2024; 10:167-194. [PMID: 39027195 PMCID: PMC11252437 DOI: 10.1002/cdt3.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 03/29/2024] [Accepted: 04/09/2024] [Indexed: 07/20/2024] Open
Abstract
Calcium-sensing receptor (CaSR), a family C G-protein-coupled receptor, plays a crucial role in regulating calcium homeostasis by sensing small concentration changes of extracellular Ca2+, Mg2+, amino acids (e.g., L-Trp and L-Phe), small peptides, anions (e.g., HCO3 - and PO4 3-), and pH. CaSR-mediated intracellular Ca2+ signaling regulates a diverse set of cellular processes including gene transcription, cell proliferation, differentiation, apoptosis, muscle contraction, and neuronal transmission. Dysfunction of CaSR with mutations results in diseases such as autosomal dominant hypocalcemia, familial hypocalciuric hypercalcemia, and neonatal severe hyperparathyroidism. CaSR also influences calciotropic disorders, such as osteoporosis, and noncalciotropic disorders, such as cancer, Alzheimer's disease, and pulmonary arterial hypertension. This study first reviews recent advances in biochemical and structural determination of the framework of CaSR and its interaction sites with natural ligands, as well as exogenous positive allosteric modulators and negative allosteric modulators. The establishment of the first CaSR protein-protein interactome network revealed 94 novel players involved in protein processing in endoplasmic reticulum, trafficking, cell surface expression, endocytosis, degradation, and signaling pathways. The roles of these proteins in Ca2+-dependent cellular physiological processes and in CaSR-dependent cellular signaling provide new insights into the molecular basis of diseases caused by CaSR mutations and dysregulated CaSR activity caused by its protein interactors and facilitate the design of therapeutic agents that target CaSR and other family C G-protein-coupled receptors.
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Affiliation(s)
- Li Tian
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging FacilityGeorgia State UniversityAtlantaGeorgiaUSA
| | - Corey Andrews
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging FacilityGeorgia State UniversityAtlantaGeorgiaUSA
| | - Qiuyun Yan
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging FacilityGeorgia State UniversityAtlantaGeorgiaUSA
| | - Jenny J. Yang
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging FacilityGeorgia State UniversityAtlantaGeorgiaUSA
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PRP4 Promotes Skin Cancer by Inhibiting Production of Melanin, Blocking Influx of Extracellular Calcium, and Remodeling Cell Actin Cytoskeleton. Int J Mol Sci 2021; 22:ijms22136992. [PMID: 34209674 PMCID: PMC8268783 DOI: 10.3390/ijms22136992] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/18/2021] [Accepted: 06/23/2021] [Indexed: 11/16/2022] Open
Abstract
Pre-mRNA processing factor 4B (PRP4) has previously been shown to induce epithelial-mesenchymal transition (EMT) and drug resistance in cancer cell lines. As melanin plays an important photoprotective role in the risk of sun-induced skin cancers, we have investigated whether PRP4 can induce drug resistance and regulate melanin biosynthesis in a murine melanoma (B16F10) cell line. Cells were incubated with a crucial melanogenesis stimulator, alpha-melanocyte-stimulating hormone, followed by transfection with PRP4. This resulted in the inhibition of the production of melanin via the downregulation of adenylyl cyclase-cyclic adenosine 3′,5′-monophosphate (AC)–(cAMP)–tyrosinase synthesis signaling pathway. Inhibition of melanin production by PRP4 leads to the promotion of carcinogenesis and induced drug resistance in B16F10 cells. Additionally, PRP4 overexpression upregulated the expression of β-arrestin 1 and desensitized the extracellular calcium-sensing receptor (CaSR), which in turn, inhibited the influx of extracellular Ca2+ ions. The decreased influx of Ca2+ was confirmed by a decreased expression level of calmodulin. We have demonstrated that transient receptor potential cation channel subfamily C member 1 was involved in the influx of CaSR-induced Ca2+ via a decreasing level of its expression. Furthermore, PRP4 overexpression downregulated the expression of AC, decreased the synthesis of cAMP, and modulated the actin cytoskeleton by inhibiting the expression of Ras homolog family member A (RhoA). Our investigation suggests that PRP4 inhibits the production of melanin in B16F10 cells, blocks the influx of Ca2+ through desensitization of CaSR, and modulates the actin cytoskeleton through downregulating the AC–cAMP pathway; taken together, these observations collectively lead to the promotion of skin carcinogenesis.
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Wen T, Wang Z, Chen X, Ren Y, Lu X, Xing Y, Lu J, Chang S, Zhang X, Shen Y, Yang X. Structural basis for activation and allosteric modulation of full-length calcium-sensing receptor. SCIENCE ADVANCES 2021; 7:7/23/eabg1483. [PMID: 34088669 PMCID: PMC8177707 DOI: 10.1126/sciadv.abg1483] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 04/19/2021] [Indexed: 06/12/2023]
Abstract
Calcium-sensing receptor (CaSR) is a class C G protein-coupled receptor (GPCR) that plays an important role in calcium homeostasis and parathyroid hormone secretion. Here, we present multiple cryo-electron microscopy structures of full-length CaSR in distinct ligand-bound states. Ligands (Ca2+ and l-tryptophan) bind to the extracellular domain of CaSR and induce large-scale conformational changes, leading to the closure of two heptahelical transmembrane domains (7TMDs) for activation. The positive modulator (evocalcet) and the negative allosteric modulator (NPS-2143) occupy the similar binding pocket in 7TMD. The binding of NPS-2143 causes a considerable rearrangement of two 7TMDs, forming an inactivated TM6/TM6 interface. Moreover, a total of 305 disease-causing missense mutations of CaSR have been mapped to the structure in the active state, creating hotspot maps of five clinical endocrine disorders. Our results provide a structural framework for understanding the activation, allosteric modulation mechanism, and disease therapy for class C GPCRs.
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Affiliation(s)
- Tianlei Wen
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin 300350, China
| | - Ziyu Wang
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin 300350, China
| | - Xiaozhe Chen
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin 300350, China
| | - Yue Ren
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin 300350, China
| | - Xuhang Lu
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin 300350, China
| | - Yangfei Xing
- State Key Laboratory of Medical Genomics, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Jing Lu
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin 300350, China
| | - Shenghai Chang
- Department of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Center of Cryo-Electron Microscopy, Zhejiang University School of Medicine, Hangzhou, China
| | - Xing Zhang
- Department of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Center of Cryo-Electron Microscopy, Zhejiang University School of Medicine, Hangzhou, China
| | - Yuequan Shen
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin 300350, China.
- Synergetic Innovation Center of Chemical Science and Engineering, Tianjin 300071, China
| | - Xue Yang
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin 300350, China.
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Gorvin CM. Calcium-sensing receptor signaling - How human disease informs biology. CURRENT OPINION IN ENDOCRINE AND METABOLIC RESEARCH 2021; 16:10-28. [PMID: 34141952 PMCID: PMC7611003 DOI: 10.1016/j.coemr.2020.06.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The calcium-sensing receptor (CaSR) is a class C G-protein-coupled receptor (GPCR) that plays a fundamental role in extracellular calcium homeostasis by regulating parathyroid hormone (PTH) release. Although the CaSR was identified over 25 years ago, new mechanistic details of how the CaSR controls PTH secretion have recently been uncovered demonstrating heteromerization and phosphate binding affect CaSR-mediated suppression of PTH release. In addition, understanding of how the CaSR performs diverse functions in different cellular contexts is just beginning to be elucidated, with new evidence of tissue-specific regulation, and endo-somal signaling. Insights into CaSR activation mechanisms and signaling bias have arisen from studies of CaSR mutations, which cause disorders of calcium homeostasis. Functional assessment of these mutations demonstrated the importance of the homodimer interface and transmembrane domain in biased signaling and showed CaSR mutations can facilitate G-protein-independent signaling. Population genetics studies have allowed a greater understanding of the prevalence of calcemic disorders and revealed new pathophysiological roles.
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Affiliation(s)
- Caroline M Gorvin
- Institute of Metabolism and Systems Research (IMSR) and Centre for Diabetes, Endocrinology and Metabolism (CEDAM), University of Birmingham, Birmingham, B15 2TT, UK
- Centre for Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, B15 2TT, UK
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Sarfraz M, Afzal A, Khattak S, Saddozai UAK, Li HM, Zhang QQ, Madni A, Haleem KS, Duan SF, Wu DD, Ji SP, Ji XY. Multifaceted behavior of PEST sequence enriched nuclear proteins in cancer biology and role in gene therapy. J Cell Physiol 2020; 236:1658-1676. [PMID: 32841373 DOI: 10.1002/jcp.30011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 07/18/2020] [Accepted: 08/04/2020] [Indexed: 01/12/2023]
Abstract
The amino acid sequence enriched with proline (P), glutamic acid (E), serine (S), and threonine (T) (PEST) is a signal-transducing agent providing unique features to its substrate nuclear proteins (PEST-NPs). The PEST motif is responsible for particular posttranslational modifications (PTMs). These PTMs impart distinct properties to PEST-NPs that are responsible for their activation/inhibition, intracellular localization, and stability/degradation. PEST-NPs participate in cancer metabolism, immunity, and protein transcription as oncogenes or as tumor suppressors. Gene-based therapeutics are getting the attention of researchers because of their cell specificity. PEST-NPs are good targets to explore as cancer therapeutics. Insights into PTMs of PEST-NPs demonstrate that these proteins not only interact with each other but also recruit other proteins to/from their active site to promote/inhibit tumors. Thus, the role of PEST-NPs in cancer biology is multivariate. It is hard to obtain therapeutic objectives with single gene therapy. An especially designed combination gene therapy might be a promising strategy in cancer treatment. This review highlights the multifaceted behavior of PEST-NPs in cancer biology. We have summarized a number of studies to address the influence of structure and PEST-mediated PTMs on activation, localization, stability, and protein-protein interactions of PEST-NPs. We also recommend researchers to adopt a pragmatic approach in gene-based cancer therapy.
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Affiliation(s)
- Muhammad Sarfraz
- Henan International Joint Laboratory for Nuclear Protein Regulation & Kaifeng Key Laboratory of Infectious Diseases and Bio-safety, School of Basic Medical Sciences, Henan University College of Medicine, Kaifeng, Henan, China.,Faculty of Pharmacy, The University of Lahore, Lahore, Punjab, Pakistan.,Kaifeng Municipal Key Laboratory of Cell Signal Transduction, Henan Provincial Engineering Centre for Tumor Molecular Medicine, Henan University, Kaifeng, Henan, China
| | - Attia Afzal
- Henan International Joint Laboratory for Nuclear Protein Regulation & Kaifeng Key Laboratory of Infectious Diseases and Bio-safety, School of Basic Medical Sciences, Henan University College of Medicine, Kaifeng, Henan, China.,Faculty of Pharmacy, The University of Lahore, Lahore, Punjab, Pakistan
| | - Saadullah Khattak
- Henan International Joint Laboratory for Nuclear Protein Regulation & Kaifeng Key Laboratory of Infectious Diseases and Bio-safety, School of Basic Medical Sciences, Henan University College of Medicine, Kaifeng, Henan, China
| | - Umair A K Saddozai
- Henan International Joint Laboratory for Nuclear Protein Regulation & Kaifeng Key Laboratory of Infectious Diseases and Bio-safety, School of Basic Medical Sciences, Henan University College of Medicine, Kaifeng, Henan, China
| | - Hui-Min Li
- Henan International Joint Laboratory for Nuclear Protein Regulation & Kaifeng Key Laboratory of Infectious Diseases and Bio-safety, School of Basic Medical Sciences, Henan University College of Medicine, Kaifeng, Henan, China.,Department of Histology and Embryology, Cell Signal Transduction Laboratory, School of Basic Medical Sciences, Bioinformatics Centre, Institute of Biomedical Informatics, Henan University, Kaifeng, Henan, China
| | - Qian-Qian Zhang
- Henan International Joint Laboratory for Nuclear Protein Regulation & Kaifeng Key Laboratory of Infectious Diseases and Bio-safety, School of Basic Medical Sciences, Henan University College of Medicine, Kaifeng, Henan, China
| | - Asadullah Madni
- Faculty of Pharmacy and Alternative Medicine, The Islamia University of Bahawalpur, Bahawalpur, Punjab, Pakistan
| | - Kashif S Haleem
- Department of Microbiology, Hazara University, Mansehra, Pakistan
| | - Shao-Feng Duan
- Henan International Joint Laboratory for Nuclear Protein Regulation & Kaifeng Key Laboratory of Infectious Diseases and Bio-safety, School of Basic Medical Sciences, Henan University College of Medicine, Kaifeng, Henan, China.,School of Pharmacy, Institute for Innovative Drug Design and Evaluation, Henan University, Kaifeng, Henan, China
| | - Dong-Dong Wu
- Henan International Joint Laboratory for Nuclear Protein Regulation & Kaifeng Key Laboratory of Infectious Diseases and Bio-safety, School of Basic Medical Sciences, Henan University College of Medicine, Kaifeng, Henan, China.,School of Stomatology, Henan University, Kaifeng, Henan, China
| | - Shao-Ping Ji
- Kaifeng Municipal Key Laboratory of Cell Signal Transduction, Henan Provincial Engineering Centre for Tumor Molecular Medicine, Henan University, Kaifeng, Henan, China
| | - Xin-Ying Ji
- Henan International Joint Laboratory for Nuclear Protein Regulation & Kaifeng Key Laboratory of Infectious Diseases and Bio-safety, School of Basic Medical Sciences, Henan University College of Medicine, Kaifeng, Henan, China
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Leach K, Hannan FM, Josephs TM, Keller AN, Møller TC, Ward DT, Kallay E, Mason RS, Thakker RV, Riccardi D, Conigrave AD, Bräuner-Osborne H. International Union of Basic and Clinical Pharmacology. CVIII. Calcium-Sensing Receptor Nomenclature, Pharmacology, and Function. Pharmacol Rev 2020; 72:558-604. [PMID: 32467152 PMCID: PMC7116503 DOI: 10.1124/pr.119.018531] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The calcium-sensing receptor (CaSR) is a class C G protein-coupled receptor that responds to multiple endogenous agonists and allosteric modulators, including divalent and trivalent cations, L-amino acids, γ-glutamyl peptides, polyamines, polycationic peptides, and protons. The CaSR plays a critical role in extracellular calcium (Ca2+ o) homeostasis, as demonstrated by the many naturally occurring mutations in the CaSR or its signaling partners that cause Ca2+ o homeostasis disorders. However, CaSR tissue expression in mammals is broad and includes tissues unrelated to Ca2+ o homeostasis, in which it, for example, regulates the secretion of digestive hormones, airway constriction, cardiovascular effects, cellular differentiation, and proliferation. Thus, although the CaSR is targeted clinically by the positive allosteric modulators (PAMs) cinacalcet, evocalcet, and etelcalcetide in hyperparathyroidism, it is also a putative therapeutic target in diabetes, asthma, cardiovascular disease, and cancer. The CaSR is somewhat unique in possessing multiple ligand binding sites, including at least five putative sites for the "orthosteric" agonist Ca2+ o, an allosteric site for endogenous L-amino acids, two further allosteric sites for small molecules and the peptide PAM, etelcalcetide, and additional sites for other cations and anions. The CaSR is promiscuous in its G protein-coupling preferences, and signals via Gq/11, Gi/o, potentially G12/13, and even Gs in some cell types. Not surprisingly, the CaSR is subject to biased agonism, in which distinct ligands preferentially stimulate a subset of the CaSR's possible signaling responses, to the exclusion of others. The CaSR thus serves as a model receptor to study natural bias and allostery. SIGNIFICANCE STATEMENT: The calcium-sensing receptor (CaSR) is a complex G protein-coupled receptor that possesses multiple orthosteric and allosteric binding sites, is subject to biased signaling via several different G proteins, and has numerous (patho)physiological roles. Understanding the complexities of CaSR structure, function, and biology will aid future drug discovery efforts seeking to target this receptor for a diversity of diseases. This review summarizes what is known to date regarding key structural, pharmacological, and physiological features of the CaSR.
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Affiliation(s)
- Katie Leach
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Fadil M Hannan
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Tracy M Josephs
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Andrew N Keller
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Thor C Møller
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Donald T Ward
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Enikö Kallay
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Rebecca S Mason
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Rajesh V Thakker
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Daniela Riccardi
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Arthur D Conigrave
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Hans Bräuner-Osborne
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
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7
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Komar AA, Merrick WC. A Retrospective on eIF2A-and Not the Alpha Subunit of eIF2. Int J Mol Sci 2020; 21:E2054. [PMID: 32192132 PMCID: PMC7139343 DOI: 10.3390/ijms21062054] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 02/29/2020] [Accepted: 03/13/2020] [Indexed: 12/31/2022] Open
Abstract
Initiation of protein synthesis in eukaryotes is a complex process requiring more than 12 different initiation factors, comprising over 30 polypeptide chains. The functions of many of these factors have been established in great detail; however, the precise role of some of them and their mechanism of action is still not well understood. Eukaryotic initiation factor 2A (eIF2A) is a single chain 65 kDa protein that was initially believed to serve as the functional homologue of prokaryotic IF2, since eIF2A and IF2 catalyze biochemically similar reactions, i.e., they stimulate initiator Met-tRNAi binding to the small ribosomal subunit. However, subsequent identification of a heterotrimeric 126 kDa factor, eIF2 (α,β,γ) showed that this factor, and not eIF2A, was primarily responsible for the binding of Met-tRNAi to 40S subunit in eukaryotes. It was found however, that eIF2A can promote recruitment of Met-tRNAi to 40S/mRNA complexes under conditions of inhibition of eIF2 activity (eIF2α-phosphorylation), or its absence. eIF2A does not function in major steps in the initiation process, but is suggested to act at some minor/alternative initiation events such as re-initiation, internal initiation, or non-AUG initiation, important for translational control of specific mRNAs. This review summarizes our current understanding of the eIF2A structure and function.
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Affiliation(s)
- Anton A. Komar
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological and Environmental Sciences, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA;
| | - William C. Merrick
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA;
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Ansari MZ, Swaminathan R. Structure and dynamics at N- and C-terminal regions of intrinsically disordered human c-Myc PEST degron reveal a pH-induced transition. Proteins 2020; 88:889-909. [PMID: 31999378 DOI: 10.1002/prot.25880] [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: 10/04/2019] [Revised: 12/09/2019] [Accepted: 01/25/2020] [Indexed: 12/11/2022]
Abstract
We investigated the structure and Brownian rotational motion of the PEST region (201-268) from human c-Myc oncoprotein, whose overexpression/dysregulation is associated with various types of cancer. The 77-residue PEST fragment revealed a large Stokes radius (~3.1 nm) and CD spectrum highlighting abundance of disordered structure. Changes in structure/dynamics at two specific sites in PEST degron were observed using time-resolved fluorescence spectroscopy by labeling Cys9 near N-terminal with dansyl probe and inserting a Trp70 near C-terminal (PEST M1). Trp in PEST M1 at pH 3 was inaccessible to quencher, showed hindered segmental motion and slow global rotation (~30 ns) in contrast to N-terminal where the dansyl probe was free, exposed with fast global rotation (~5 ns). Remarkably, this large monomeric structure at acidic pH was retained irrespective of ionic strength (0.03-0.25 M) and partially so in presence of 6 M Gdn.HCl. With gradual increase in pH, a structural transition (~pH 4.8) into a more exposed and freely rotating Trp was noticeable. Interestingly, the induced structure at C-terminal also influenced the dynamics of dansyl probe near N-terminal, which otherwise remained unstructured at pH > 5. FRET measurements confirmed a 11 Å decrease in distance between dansyl and indole at pH 4 compared to pH 9, coinciding with enhanced ANS binding and increase in strand/helix population in both PEST fragments. The protonation of glutamate/aspartate residues in C-terminal region of PEST is implicated in this disorder-order transition. This may have a bearing on the role of PEST in endocytic trafficking of eukaryotic proteins.
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Affiliation(s)
- Mohd Ziauddin Ansari
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
| | - Rajaram Swaminathan
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
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Sensing Extracellular Calcium - An Insight into the Structure and Function of the Calcium-Sensing Receptor (CaSR). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:1031-1063. [PMID: 31646544 DOI: 10.1007/978-3-030-12457-1_41] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The calcium-sensing receptor (CaSR) is a G protein-coupled receptor that plays a key role in calcium homeostasis, by sensing free calcium levels in blood and regulating parathyroid hormone secretion in response. The CaSR is highly expressed in parathyroid gland and kidney where its role is well characterised, but also in other tissues where its function remains to be determined. The CaSR can be activated by a variety of endogenous ligands, as well as by synthetic modulators such as Cinacalcet, used in the clinic to treat secondary hyperparathyroidism in patients with chronic kidney disease. The CaSR couples to multiple G proteins, in a tissue-specific manner, activating several signalling pathways and thus regulating diverse intracellular events. The multifaceted nature of this receptor makes it a valuable therapeutic target for calciotropic and non-calciotropic diseases. It is therefore essential to understand the complexity behind the pharmacology, trafficking, and signalling characteristics of this receptor. This review provides an overview of the latest knowledge about the CaSR and discusses future hot topics in this field.
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10
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Dal Prà I, Armato U, Chiarini A. Family C G-Protein-Coupled Receptors in Alzheimer's Disease and Therapeutic Implications. Front Pharmacol 2019; 10:1282. [PMID: 31719824 PMCID: PMC6826475 DOI: 10.3389/fphar.2019.01282] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 10/07/2019] [Indexed: 12/12/2022] Open
Abstract
Alzheimer’s disease (AD), particularly its sporadic or late-onset form (SAD/LOAD), is the most prevalent (96–98% of cases) neurodegenerative dementia in aged people. AD’s neuropathology hallmarks are intrabrain accumulation of amyloid-β peptides (Aβs) and of hyperphosphorylated Tau (p-Tau) proteins, diffuse neuroinflammation, and progressive death of neurons and oligodendrocytes. Mounting evidences suggest that family C G-protein-coupled receptors (GPCRs), which include γ-aminobutyric acid B receptors (GABABRs), metabotropic glutamate receptors (mGluR1-8), and the calcium-sensing receptor (CaSR), are involved in many neurotransmitter systems that dysfunction in AD. This review updates the available knowledge about the roles of GPCRs, particularly but not exclusively those expressed by brain astrocytes, in SAD/LOAD onset and progression, taking stock of their respective mechanisms of action and of their potential as anti-AD therapeutic targets. In particular, GABABRs prevent Aβs synthesis and neuronal hyperexcitability and group I mGluRs play important pathogenetic roles in transgenic AD-model animals. Moreover, the specific binding of Aβs to the CaSRs of human cortical astrocytes and neurons cultured in vitro engenders a pathological signaling that crucially promotes the surplus synthesis and release of Aβs and hyperphosphorylated Tau proteins, and also of nitric oxide, vascular endothelial growth factor-A, and proinflammatory agents. Concurrently, Aβs•CaSR signaling hinders the release of soluble (s)APP-α peptide, a neurotrophic agent and GABABR1a agonist. Altogether these effects progressively kill human cortical neurons in vitro and likely also in vivo. Several CaSR’s negative allosteric modulators suppress all the noxious effects elicited by Aβs•CaSR signaling in human cortical astrocytes and neurons thus safeguarding neurons’ viability in vitro and raising hopes about their potential therapeutic benefits in AD patients. Further basic and clinical investigations on these hot topics are needed taking always heed that activation of the several brain family C GPCRs may elicit divergent upshots according to the models studied.
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Affiliation(s)
- Ilaria Dal Prà
- Human Histology and Embryology Unit, University of Verona Medical School, Verona, Italy
| | - Ubaldo Armato
- Human Histology and Embryology Unit, University of Verona Medical School, Verona, Italy
| | - Anna Chiarini
- Human Histology and Embryology Unit, University of Verona Medical School, Verona, Italy
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Mos I, Jacobsen SE, Foster SR, Bräuner-Osborne H. Calcium-Sensing Receptor Internalization Isβ-Arrestin–Dependent and Modulated by Allosteric Ligands. Mol Pharmacol 2019; 96:463-474. [DOI: 10.1124/mol.119.116772] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 07/30/2019] [Indexed: 12/18/2022] Open
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12
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Qile M, Ji Y, Houtman MJC, Veldhuis M, Romunde F, Kok B, van der Heyden MAG. Identification of a PEST Sequence in Vertebrate K IR2.1 That Modifies Rectification. Front Physiol 2019; 10:863. [PMID: 31333502 PMCID: PMC6624654 DOI: 10.3389/fphys.2019.00863] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 06/20/2019] [Indexed: 11/13/2022] Open
Abstract
KIR2.1 potassium channels, producing inward rectifier potassium current (IK1), are important for final action potential repolarization and a stable resting membrane potential in excitable cells like cardiomyocytes. Abnormal KIR2.1 function, either decreased or increased, associates with diseases such as Andersen-Tawil syndrome, long and short QT syndromes. KIR2.1 ion channel protein trafficking and subcellular anchoring depends on intrinsic specific short amino acid sequences. We hypothesized that combining an evolutionary based sequence comparison and bioinformatics will identify new functional domains within the C-terminus of the KIR2.1 protein, which function could be determined by mutation analysis. We determined PEST domain signatures, rich in proline (P), glutamic acid (E), serine (S), and threonine (T), within KIR2.1 sequences using the “epestfind” webtool. WT and ΔPEST KIR2.1 channels were expressed in HEK293T and COS-7 cells. Patch-clamp electrophysiology measurements were performed in the inside-out mode on excised membrane patches and the whole cell mode using AxonPatch 200B amplifiers. KIR2.1 protein expression levels were determined by western blot analysis. Immunofluorescence microscopy was used to determine KIR2.1 subcellular localization. An evolutionary conserved PEST domain was identified in the C-terminus of the KIR2.1 channel protein displaying positive PEST scores in vertebrates ranging from fish to human. No similar PEST domain was detected in KIR2.2, KIR2.3, and KIR2.6 proteins. Deletion of the PEST domain in California kingsnake and human KIR2.1 proteins (ΔPEST), did not affect plasma membrane localization. Co-expression of WT and ΔPEST KIR2.1 proteins resulted in heterotetrameric channel formation. Deletion of the PEST domain did not increase protein stability in cycloheximide assays [T½ from 2.64 h (WT) to 1.67 h (ΔPEST), n.s.]. WT and ΔPEST channels, either from human or snake, produced typical IK1, however, human ΔPEST channels displayed stronger intrinsic rectification. The current observations suggest that the PEST sequence of KIR2.1 is not associated with rapid protein degradation, and has a role in the rectification behavior of IK1 channels.
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Affiliation(s)
- Muge Qile
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Yuan Ji
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Marien J C Houtman
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Marlieke Veldhuis
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Fee Romunde
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Bart Kok
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Marcel A G van der Heyden
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
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Sensory Axon Growth Requires Spatiotemporal Integration of CaSR and TrkB Signaling. J Neurosci 2019; 39:5842-5860. [PMID: 31123102 DOI: 10.1523/jneurosci.0027-19.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 05/12/2019] [Accepted: 05/15/2019] [Indexed: 12/18/2022] Open
Abstract
Neural circuit development involves the coordinated growth and guidance of axons. During this process, axons encounter many different cues, but how these cues are integrated and translated into growth is poorly understood. In this study, we report that receptor signaling does not follow a linear path but changes dependent on developmental stage and coreceptors involved. Using developing chicken embryos of both sexes, our data show that calcium-sensing receptor (CaSR), a G-protein-coupled receptor important for regulating calcium homeostasis, regulates neurite growth in two distinct ways. First, when signaling in isolation, CaSR promotes growth through the PI3-kinase-Akt pathway. At later developmental stages, CaSR enhances tropomyosin receptor kinase B (TrkB)/BDNF-mediated neurite growth. This enhancement is facilitated through a switch in the signaling cascade downstream of CaSR (i.e., from the PI3-kinase-Akt pathway to activation of GSK3α Tyr279). TrkB and CaSR colocalize within late endosomes, cotraffic and coactivate GSK3, which serves as a shared signaling node for both receptors. Our study provides evidence that two unrelated receptors can integrate their individual signaling cascades toward a nonadditive effect and thus control neurite growth during development.SIGNIFICANCE STATEMENT This work highlights the effect of receptor coactivation and signal integration in a developmental setting. During embryonic development, neurites grow toward their targets guided by cues in the extracellular environment. These cues are sensed by receptors at the surface that trigger intracellular signaling events modulating the cytoskeleton. Emerging evidence suggests that the effects of guidance cues are diversified, therefore expanding the number of responses. Here, we show that two unrelated receptors can change the downstream signaling cascade and regulate neuronal growth through a shared signaling node. In addition to unraveling a novel signaling pathway in neurite growth, this research stresses the importance of receptor coactivation and signal integration during development of the nervous system.
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14
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Chen C, Nguyen BN, Mitchell G, Margolis SR, Ma D, Portnoy DA. The Listeriolysin O PEST-like Sequence Co-opts AP-2-Mediated Endocytosis to Prevent Plasma Membrane Damage during Listeria Infection. Cell Host Microbe 2019; 23:786-795.e5. [PMID: 29902442 DOI: 10.1016/j.chom.2018.05.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 04/23/2018] [Accepted: 05/11/2018] [Indexed: 10/14/2022]
Abstract
Listeriolysin O (LLO) is a cholesterol-dependent cytolysin that mediates escape of Listeria monocytogenes from a phagosome, enabling growth of the bacteria in the host cell cytosol. LLO contains a PEST-like sequence that prevents it from killing infected cells, but the mechanism involved is unknown. We found that the LLO PEST-like sequence was necessary to mediate removal of LLO from the interior face of the plasma membrane, where it coalesces into discrete puncta. LLO interacts with Ap2a2, an adaptor protein involved in endocytosis, via its PEST-like sequence, and Ap2a2-dependent endocytosis is required to prevent LLO-induced cytotoxicity. An unrelated PEST-like sequence from a human G protein-coupled receptor (GPCR), which also interacts with Ap2a2, could functionally complement the PEST-like sequence in L. monocytogenes LLO. These data revealed that LLO co-opts the host endocytosis machinery to protect the integrity of the host plasma membrane during L. monocytogenes infection.
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Affiliation(s)
- Chen Chen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Brittney N Nguyen
- Graduate Group in Microbiology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Gabriel Mitchell
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Shally R Margolis
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Darren Ma
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Daniel A Portnoy
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; School of Public Health, University of California, Berkeley, Berkeley, CA 94720, USA.
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Hannan FM, Kallay E, Chang W, Brandi ML, Thakker RV. The calcium-sensing receptor in physiology and in calcitropic and noncalcitropic diseases. Nat Rev Endocrinol 2018; 15:33-51. [PMID: 30443043 PMCID: PMC6535143 DOI: 10.1038/s41574-018-0115-0] [Citation(s) in RCA: 191] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The Ca2+-sensing receptor (CaSR) is a dimeric family C G protein-coupled receptor that is expressed in calcitropic tissues such as the parathyroid glands and the kidneys and signals via G proteins and β-arrestin. The CaSR has a pivotal role in bone and mineral metabolism, as it regulates parathyroid hormone secretion, urinary Ca2+ excretion, skeletal development and lactation. The importance of the CaSR for these calcitropic processes is highlighted by loss-of-function and gain-of-function CaSR mutations that cause familial hypocalciuric hypercalcaemia and autosomal dominant hypocalcaemia, respectively, and also by the fact that alterations in parathyroid CaSR expression contribute to the pathogenesis of primary and secondary hyperparathyroidism. Moreover, the CaSR is an established therapeutic target for hyperparathyroid disorders. The CaSR is also expressed in organs not involved in Ca2+ homeostasis: it has noncalcitropic roles in lung and neuronal development, vascular tone, gastrointestinal nutrient sensing, wound healing and secretion of insulin and enteroendocrine hormones. Furthermore, the abnormal expression or function of the CaSR is implicated in cardiovascular and neurological diseases, as well as in asthma, and the CaSR is reported to protect against colorectal cancer and neuroblastoma but increase the malignant potential of prostate and breast cancers.
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Affiliation(s)
- Fadil M Hannan
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Enikö Kallay
- Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria
| | - Wenhan Chang
- Endocrine Research Unit, Veterans Affairs Medical Center, University of California, San Francisco, San Francisco, CA, USA
| | - Maria Luisa Brandi
- Metabolic Bone Diseases Unit, Department of Surgery and Translational Medicine, University of Florence, Florence, Italy.
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
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16
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Ireton K. A Helpful PEST for Listeriolysin O? Cell Host Microbe 2018; 23:693-694. [PMID: 29902431 DOI: 10.1016/j.chom.2018.05.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Listeriolysin O (LLO) perforates host vacuoles, allowing Listeria monocytogenes to escape to the cytosol. How cytosolic LLO prevents cell lysis was not understood. In this issue of Cell Host & Microbe, Chen et al. (2018) show that a PEST sequence prevents cytotoxicity by mediating LLO endocytosis from the plasma membrane.
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Affiliation(s)
- Keith Ireton
- Department of Microbiology and Immunology, University of Otago, Dunedin 9054, New Zealand.
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Jacobsen SE, Ammendrup-Johnsen I, Jansen AM, Gether U, Madsen KL, Bräuner-Osborne H. The GPRC6A receptor displays constitutive internalization and sorting to the slow recycling pathway. J Biol Chem 2017; 292:6910-6926. [PMID: 28280242 DOI: 10.1074/jbc.m116.762385] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 02/27/2017] [Indexed: 11/06/2022] Open
Abstract
The class C G protein-coupled receptor GPRC6A is a putative nutrient-sensing receptor and represents a possible new drug target in metabolic disorders. However, the specific physiological role of this receptor has yet to be identified, and the mechanisms regulating its activity and cell surface availability also remain enigmatic. In the present study, we investigated the trafficking properties of GPRC6A by use of both a classical antibody feeding internalization assay in which cells were visualized using confocal microscopy and a novel internalization assay that is based on real-time measurements of fluorescence resonance energy transfer. Both assays revealed that GPRC6A predominantly undergoes constitutive internalization, whereas the agonist-induced effects were imperceptible. Moreover, postendocytic sorting was investigated by assessing the co-localization of internalized GPRC6A with selected Rab protein markers. Internalized GPRC6A was mainly co-localized with the early endosome marker Rab5 and the long loop recycling endosome marker Rab11 and to a much lesser extent with the late endosome marker Rab7. This suggests that upon agonist-independent internalization, GPRC6A is recycled via the Rab11-positive slow recycling pathway, which may be responsible for ensuring a persistent pool of GPRC6A receptors at the cell surface despite chronic agonist exposure. Distinct trafficking pathways have been reported for several of the class C receptors, and our results thus substantiate that non-canonical trafficking mechanisms are a common feature for the nutrient-sensing class C family that ensure functional receptors in the cell membrane despite prolonged agonist exposure.
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Affiliation(s)
- Stine Engesgaard Jacobsen
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark and
| | - Ina Ammendrup-Johnsen
- Molecular Neuropharmacology Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Anna Mai Jansen
- Molecular Neuropharmacology Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Ulrik Gether
- Molecular Neuropharmacology Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Kenneth Lindegaard Madsen
- Molecular Neuropharmacology Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Hans Bräuner-Osborne
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark and
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18
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Zhang C, Miller CL, Gorkhali R, Zou J, Huang K, Brown EM, Yang JJ. Molecular Basis of the Extracellular Ligands Mediated Signaling by the Calcium Sensing Receptor. Front Physiol 2016; 7:441. [PMID: 27746744 PMCID: PMC5043022 DOI: 10.3389/fphys.2016.00441] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 09/16/2016] [Indexed: 12/20/2022] Open
Abstract
Ca2+-sensing receptors (CaSRs) play a central role in regulating extracellular calcium concentration ([Ca2+]o) homeostasis and many (patho)physiological processes in multiple organs. This regulation is orchestrated by a cooperative response to extracellular stimuli such as small changes in Ca2+, Mg2+, amino acids, and other ligands. In addition, CaSR is a pleiotropic receptor regulating several intracellular signaling pathways, including calcium mobilization and intracellular calcium oscillation. Nearly 200 mutations and polymorphisms have been found in CaSR in relation to a variety of human disorders associated with abnormal Ca2+ homeostasis. In this review, we summarize efforts directed at identifying binding sites for calcium and amino acids. Both homotropic cooperativity among multiple calcium binding sites and heterotropic cooperativity between calcium and amino acid were revealed using computational modeling, predictions, and site-directed mutagenesis coupled with functional assays. The hinge region of the bilobed Venus flytrap (VFT) domain of CaSR plays a pivotal role in coordinating multiple extracellular stimuli, leading to cooperative responses from the receptor. We further highlight the extensive number of disease-associated mutations that have also been shown to affect CaSR's cooperative action via several types of mechanisms. These results provide insights into the molecular bases of the structure and functional cooperativity of this receptor and other members of family C of the G protein-coupled receptors (cGPCRs) in health and disease states, and may assist in the prospective development of novel receptor-based therapeutics.
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Affiliation(s)
- Chen Zhang
- Department of Chemistry, Georgia State University Atlanta, GA, USA
| | | | - Rakshya Gorkhali
- Department of Chemistry, Georgia State University Atlanta, GA, USA
| | - Juan Zou
- Department of Chemistry, Georgia State University Atlanta, GA, USA
| | - Kenneth Huang
- Department of Chemistry, Georgia State University Atlanta, GA, USA
| | - Edward M Brown
- Center for Diagnostics and Therapeutics, Georgia State UniversityAtlanta, GA, USA; Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's HospitalBoston, MA, USA
| | - Jenny J Yang
- Department of Chemistry, Georgia State University Atlanta, GA, USA
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Obermannova B, Sumnik Z, Dusatkova P, Cinek O, Grant M, Lebl J, Hendy GN. Novel calcium-sensing receptor cytoplasmic tail deletion mutation causing autosomal dominant hypocalcemia: molecular and clinical study. Eur J Endocrinol 2016; 174:K1-K11. [PMID: 26764418 DOI: 10.1530/eje-15-1216] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Accepted: 01/12/2016] [Indexed: 01/15/2023]
Abstract
OBJECTIVE Autosomal dominant hypocalcemia (ADH) is a rare disorder caused by activating mutations of the calcium-sensing receptor (CASR). The treatment of ADH patients with 1α-hydroxylated vitamin D derivatives can cause hypercalciuria leading to nephrocalcinosis. DESIGN AND METHODS We studied a girl who presented with hypoparathyroidism and asymptomatic hypocalcemia at age 2.5 years. Mutations of CASR were investigated by DNA sequencing. Functional analyses of mutant and WT CASRs were done in transiently transfected human embryonic kidney (HEK293) cells. RESULTS The proband and her father are heterozygous for an eight-nucleotide deletion c.2703_2710delCCTTGGAG in the CASR encoding the intracellular domain of the protein. Transient expression of CASR constructs in kidney cells in vitro suggested greater cell surface expression of the mutant receptor with a left-shifted extracellular calcium dose-response curve relative to that of the WT receptor consistent with gain of function. Initial treatment of the patient with calcitriol led to increased urinary calcium excretion. Evaluation for mosaicism in the paternal grandparents of the proband was negative. CONCLUSIONS We describe a novel naturally occurring deletion mutation within the CASR that apparently arose de novo in the father of the ADH proband. Functional analysis suggests that the cytoplasmic tail of the CASR contains determinants that regulate the attenuation of signal transduction. Early molecular analysis of the CASR gene in patients with isolated idiopathic hypoparathyroidism is recommended because of its relevance to clinical outcome and treatment choice. In ADH patients, calcium supplementation and low-dose cholecalciferol avoids hypocalcemic symptoms without compromising renal function.
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Affiliation(s)
- Barbora Obermannova
- Department of PediatricsSecond Faculty of Medicine, Charles University in Prague, University Hospital Motol V Uvalu 84, CZ-150 06 Prague, Czech RepublicLady Davis Institute for Medical ResearchSMBD-Jewish General Hospital, McGill University, Montréal, Québec, Canada H3T 1E2Experimental Therapeutics and MetabolismRoom No. EM1.3226 RI-McGill University Health Centre Glen Site, 1001 Décarie Boulevard, Montréal, Québec, Canada H4A 3J1Departments of MedicinePhysiology, and Human Genetics, McGill University, Montréal, Québec, Canada H4A 3J1
| | - Zdenek Sumnik
- Department of PediatricsSecond Faculty of Medicine, Charles University in Prague, University Hospital Motol V Uvalu 84, CZ-150 06 Prague, Czech RepublicLady Davis Institute for Medical ResearchSMBD-Jewish General Hospital, McGill University, Montréal, Québec, Canada H3T 1E2Experimental Therapeutics and MetabolismRoom No. EM1.3226 RI-McGill University Health Centre Glen Site, 1001 Décarie Boulevard, Montréal, Québec, Canada H4A 3J1Departments of MedicinePhysiology, and Human Genetics, McGill University, Montréal, Québec, Canada H4A 3J1
| | - Petra Dusatkova
- Department of PediatricsSecond Faculty of Medicine, Charles University in Prague, University Hospital Motol V Uvalu 84, CZ-150 06 Prague, Czech RepublicLady Davis Institute for Medical ResearchSMBD-Jewish General Hospital, McGill University, Montréal, Québec, Canada H3T 1E2Experimental Therapeutics and MetabolismRoom No. EM1.3226 RI-McGill University Health Centre Glen Site, 1001 Décarie Boulevard, Montréal, Québec, Canada H4A 3J1Departments of MedicinePhysiology, and Human Genetics, McGill University, Montréal, Québec, Canada H4A 3J1
| | - Ondrej Cinek
- Department of PediatricsSecond Faculty of Medicine, Charles University in Prague, University Hospital Motol V Uvalu 84, CZ-150 06 Prague, Czech RepublicLady Davis Institute for Medical ResearchSMBD-Jewish General Hospital, McGill University, Montréal, Québec, Canada H3T 1E2Experimental Therapeutics and MetabolismRoom No. EM1.3226 RI-McGill University Health Centre Glen Site, 1001 Décarie Boulevard, Montréal, Québec, Canada H4A 3J1Departments of MedicinePhysiology, and Human Genetics, McGill University, Montréal, Québec, Canada H4A 3J1
| | - Michael Grant
- Department of PediatricsSecond Faculty of Medicine, Charles University in Prague, University Hospital Motol V Uvalu 84, CZ-150 06 Prague, Czech RepublicLady Davis Institute for Medical ResearchSMBD-Jewish General Hospital, McGill University, Montréal, Québec, Canada H3T 1E2Experimental Therapeutics and MetabolismRoom No. EM1.3226 RI-McGill University Health Centre Glen Site, 1001 Décarie Boulevard, Montréal, Québec, Canada H4A 3J1Departments of MedicinePhysiology, and Human Genetics, McGill University, Montréal, Québec, Canada H4A 3J1
| | - Jan Lebl
- Department of PediatricsSecond Faculty of Medicine, Charles University in Prague, University Hospital Motol V Uvalu 84, CZ-150 06 Prague, Czech RepublicLady Davis Institute for Medical ResearchSMBD-Jewish General Hospital, McGill University, Montréal, Québec, Canada H3T 1E2Experimental Therapeutics and MetabolismRoom No. EM1.3226 RI-McGill University Health Centre Glen Site, 1001 Décarie Boulevard, Montréal, Québec, Canada H4A 3J1Departments of MedicinePhysiology, and Human Genetics, McGill University, Montréal, Québec, Canada H4A 3J1
| | - Geoffrey N Hendy
- Department of PediatricsSecond Faculty of Medicine, Charles University in Prague, University Hospital Motol V Uvalu 84, CZ-150 06 Prague, Czech RepublicLady Davis Institute for Medical ResearchSMBD-Jewish General Hospital, McGill University, Montréal, Québec, Canada H3T 1E2Experimental Therapeutics and MetabolismRoom No. EM1.3226 RI-McGill University Health Centre Glen Site, 1001 Décarie Boulevard, Montréal, Québec, Canada H4A 3J1Departments of MedicinePhysiology, and Human Genetics, McGill University, Montréal, Québec, Canada H4A 3J1 Department of PediatricsSecond Faculty of Medicine, Charles University in Prague, University Hospital Motol V Uvalu 84, CZ-150 06 Prague, Czech RepublicLady Davis Institute for Medical ResearchSMBD-Jewish General Hospital, McGill University, Montréal, Québec, Canada H3T 1E2Experimental Therapeutics and MetabolismRoom No. EM1.3226 RI-McGill University Health Centre Glen Site, 1001 Décarie Boulevard, Montréal, Québec, Canada H4A 3J1Departments of MedicinePhysiology, and Human Genetics, McGill University, Montréal, Québec, Canada H4A 3J1
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Grant MP, Cavanaugh A, Breitwieser GE. 14-3-3 Proteins Buffer Intracellular Calcium Sensing Receptors to Constrain Signaling. PLoS One 2015; 10:e0136702. [PMID: 26317416 PMCID: PMC4552738 DOI: 10.1371/journal.pone.0136702] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2015] [Accepted: 08/06/2015] [Indexed: 12/04/2022] Open
Abstract
Calcium sensing receptors (CaSR) interact with 14-3-3 binding proteins at a carboxyl terminal arginine-rich motif. Mutations identified in patients with familial hypocalciuric hypercalcemia, autosomal dominant hypocalcemia, pancreatitis or idiopathic epilepsy support the functional importance of this motif. We combined total internal reflection fluorescence microscopy and biochemical approaches to determine the mechanism of 14-3-3 protein regulation of CaSR signaling. Loss of 14-3-3 binding caused increased basal CaSR signaling and plasma membrane levels, and a significantly larger signaling-evoked increase in plasma membrane receptors. Block of core glycosylation with tunicamycin demonstrated that changes in plasma membrane CaSR levels were due to differences in exocytic rate. Western blotting to quantify time-dependent changes in maturation of expressed wt CaSR and a 14-3-3 protein binding-defective mutant demonstrated that signaling increases synthesis to maintain constant levels of the immaturely and maturely glycosylated forms. CaSR thus operates by a feed-forward mechanism, whereby signaling not only induces anterograde trafficking of nascent receptors but also increases biosynthesis to maintain steady state levels of net cellular CaSR. Overall, these studies suggest that 14-3-3 binding at the carboxyl terminus provides an important buffering mechanism to increase the intracellular pool of CaSR available for signaling-evoked trafficking, but attenuates trafficking to control the dynamic range of responses to extracellular calcium.
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Affiliation(s)
- Michael P. Grant
- Weis Center for Research, Geisinger Clinic, Danville, Pennsylvania, United States of America
| | - Alice Cavanaugh
- Weis Center for Research, Geisinger Clinic, Danville, Pennsylvania, United States of America
| | - Gerda E. Breitwieser
- Weis Center for Research, Geisinger Clinic, Danville, Pennsylvania, United States of America
- * E-mail:
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Zhang C, Miller CL, Brown EM, Yang JJ. The calcium sensing receptor: from calcium sensing to signaling. SCIENCE CHINA-LIFE SCIENCES 2015; 58:14-27. [DOI: 10.1007/s11427-014-4779-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Accepted: 10/21/2014] [Indexed: 12/14/2022]
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Calcium-Sensing Receptor. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 132:127-50. [DOI: 10.1016/bs.pmbts.2015.02.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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A mechanism for epithelial-mesenchymal transition and anoikis resistance in breast cancer triggered by zinc channel ZIP6 and STAT3 (signal transducer and activator of transcription 3). Biochem J 2013; 455:229-37. [PMID: 23919497 PMCID: PMC3789231 DOI: 10.1042/bj20130483] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Genes involved in normal developmental processes attract attention as mediators of tumour progression as they facilitate migration of tumour cells. EMT (epithelial–mesenchymal transition), an essential part of embryonic development, tissue remodelling and wound repair, is crucial for tumour metastasis. Previously, zinc transporter ZIP6 [SLC39A6; solute carrier family 39 (zinc transporter), member 6; also known as LIV-1) was linked to EMT in zebrafish gastrulation through a STAT3 (signal transducer and activator of transcription 3) mechanism, resulting in nuclear localization of transcription factor Snail. In the present study, we show that zinc transporter ZIP6 is transcriptionally induced by STAT3 and unprecedented among zinc transporters, and is activated by N-terminal cleavage which triggers ZIP6 plasma membrane location and zinc influx. This zinc influx inactivates GSK-3β (glycogen synthase kinase 3β), either indirectly or directly via Akt or GSK-3β respectively, resulting in activation of Snail, which remains in the nucleus and acts as a transcriptional repressor of E-cadherin (epithelial cadherin), CDH1, causing cell rounding and detachment. This was mirrored by ZIP6-transfected cells which underwent EMT, detached from monolayers and exhibited resistance to anoikis by their ability to continue proliferating even after detachment. Our results indicate a causative role for ZIP6 in cell motility and migration, providing ZIP6 as a new target for prediction of clinical cancer spread and also suggesting a ZIP6-dependent mechanism of tumour metastasis. We demonstrate a novel mechanism for the ability of cellular zinc to drive cell detachment and migration with implications for breast cancer spread. This mechanism involves a zinc uptake channel ZIP6 (also known as SLC39A6) and a transcription factor, STAT3.
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Hendy GN, Canaff L, Cole DEC. The CASR gene: alternative splicing and transcriptional control, and calcium-sensing receptor (CaSR) protein: structure and ligand binding sites. Best Pract Res Clin Endocrinol Metab 2013; 27:285-301. [PMID: 23856260 DOI: 10.1016/j.beem.2013.02.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The calcium-sensing receptor (CaSR) is a G protein-coupled receptor encoded by a single copy gene. The human CASR gene spans ~103-kb and has eight exons. Promoters P1 and P2 drive transcription of exons 1A and 1B, respectively, encoding alternative 5'-UTRs that splice to exon 2 encoding the common part of the 5'-UTR. Exons 2-7 encode the CaSR protein of 1078 amino acids. Functional elements responsive to 1,25-dihydroxyvitamin D, proinflammatory cytokines, and glial cells missing-2 are present in the CASR promoters. Evolutionarily, the exon structure, first seen in aquatic vertebrates, is well-conserved with a single linkage disequilibrium haplotype block for protein coding exons 2-7. Structural features of the human CaSR protein are: an N-terminal signal peptide (19 amino acids (aa)); an extracellular domain (~600 aa) having a bi-lobed Venus Flytrap (VFT) domain with several Ca(2+)-binding sites; and a nine-cysteines domain that transduces the activation signal to the 7-transmembrane domain (250 aa) and the C-terminal tail (216 aa).
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Affiliation(s)
- Geoffrey N Hendy
- Calcium Research Laboratory, and Hormones and Cancer Research Unit, Royal Victoria Hospital and McGill University Health Centre, Montreal, QC H3A 1A1, Canada.
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Breitwieser GE. The calcium sensing receptor life cycle: trafficking, cell surface expression, and degradation. Best Pract Res Clin Endocrinol Metab 2013; 27:303-13. [PMID: 23856261 DOI: 10.1016/j.beem.2013.03.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The calcium-sensing receptor (CaSR) must function in the chronic presence of agonist, and recent studies suggest that its ability to signal under such conditions depends upon the unique mechanism(s) regulating its cellular trafficking. This chapter will highlight the evidence supporting an intracellular endoplasmic reticulum-localized pool of CaSR that can be mobilized to the plasma membrane by CaSR signaling, leading to agonist-driven insertional signaling (ADIS). I summarize evidence for the role of small GTP binding proteins (Rabs, Sar1 and ARFs), cargo receptors or chaperones (p24A, RAMPs) and interacting proteins (14-3-3 proteins, calmodulin) in anterograde trafficking of CaSR, and discuss the potential signaling specializations arising from CaSR interactions with caveolins or Filamin A/Rho. Finally, I summarize current knowledge about CaSR endocytosis and degradation by both the proteasome and lysosome, and highlight recent studies indicating that defective trafficking of CaSR or interacting protein mutants contributes to pathology in disorders of calcium homeostasis.
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Affiliation(s)
- Gerda E Breitwieser
- Weis Center for Research, Geisinger Clinic, 100 N. Academy Avenue, Danville, PA 17822-2604, USA.
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Vertebrate extracellular calcium-sensing receptor evolution: selection in relation to life history and habitat. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2012; 8:86-94. [PMID: 23321268 DOI: 10.1016/j.cbd.2012.12.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Revised: 12/07/2012] [Accepted: 12/09/2012] [Indexed: 11/20/2022]
Abstract
Ionic calcium (Ca(2+)) supports essential functions within physiological systems, and consequently its concentration is homeostatically regulated within narrow bounds in the body fluids of animals through endocrine effects at ion-transporting osmoregulatory tissues. In vertebrates, extracellular Ca(2+) is detected at the cell surface by the extracellular calcium-sensing receptor (CaSR), a member of the G protein-coupled receptor (GPCR) superfamily. Interestingly, the taxonomic distribution of CaSRs is restricted to vertebrates, with some CaSR-like receptors apparently present in non-vertebrate chordates. Since bone is a known Ca(2+) storage site and is characteristically restricted to the vertebrate lineage, we hypothesized a functional association of CaSR with vertebrate skeleton that may have an ancient origin. Protein sequence alignment and phylogenetic analysis of vertebrate CaSRs and related GPCRs of the glutamate receptor-like family expose similarities and indel differences among these receptors, and reveal the evolutionary history of CaSRs. Evolutionary selection was tested statistically by evaluating the relationship between non-synonymous (replacement, dN) versus synonymous (silent, dS) amino acid substitution rates (as dN/dS) of protein-coding DNA sequences among branches of the estimated protein phylogeny. On a background of strong purifying selection (dN/dS<1) in the CaSR phylogeny, statistical evidence for adaptive evolution (dN/dS>1) was detected on some branches to major clades in the CaSR phylogeny, especially to the tetrapod vertebrate CaSRs and chordate CaSR-like branches. Testing also revealed overall purifying selection at the codon level. At some sites relaxation from strong purifying selection was seen, but evidence for adaptive evolution was not detected for individual sites. The results suggest purifying selection of CaSRs, and of adaptive evolution among some major vertebrate clades, reflecting clade specific differences in natural history and organismal biology, including skeletal involvement in calcium homeostasis.
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Breitwieser GE. Minireview: the intimate link between calcium sensing receptor trafficking and signaling: implications for disorders of calcium homeostasis. Mol Endocrinol 2012; 26:1482-95. [PMID: 22745192 DOI: 10.1210/me.2011-1370] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The calcium-sensing receptor (CaSR) regulates organismal Ca(2+) homeostasis. Dysregulation of CaSR expression or mutations in the CASR gene cause disorders of Ca(2+) homeostasis and contribute to the progression or severity of cancers and cardiovascular disease. This brief review highlights recent findings that define the CaSR life cycle, which controls the cellular abundance of CaSR and CaSR signaling. A novel mechanism, termed agonist-driven insertional signaling (ADIS), contributes to the unique hallmarks of CaSR signaling, including the high degree of cooperativity and the lack of functional desensitization. Agonist-mediated activation of plasma membrane-localized CaSR increases the rate of insertion of CaSR at the plasma membrane without altering the constitutive endocytosis rate, thereby acutely increasing the maximum signaling response. Prolonged CaSR signaling requires a large intracellular ADIS-mobilizable pool of CaSR, which is maintained by signaling-mediated increases in biosynthesis. This model provides a rational framework for characterizing the defects caused by CaSR mutations and the altered functional expression of wild-type CaSR in disease states. Mechanistic dissection of ADIS of CaSR should lead to optimized pharmacological approaches to normalize CaSR signaling in disorders of Ca(2+) homeostasis.
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Affiliation(s)
- Gerda E Breitwieser
- Weis Center for Research, Geisinger Clinic, Danville, Pennsylvania 17822-2604, USA.
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