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Culhane KJ, Belina ME, Sims JN, Cai Y, Liu Y, Wang PSP, Yan ECY. Parathyroid Hormone Senses Extracellular Calcium To Modulate Endocrine Signaling upon Binding to the Family B GPCR Parathyroid Hormone 1 Receptor. ACS Chem Biol 2018; 13:2347-2358. [PMID: 29952553 PMCID: PMC10640708 DOI: 10.1021/acschembio.8b00568] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Parathyroid hormone (PTH) binds to a family B G protein coupled receptor, parathyroid hormone 1 receptor (PTH1R). One of its functions is to regulate Ca2+ homeostasis in bone remodeling, during which Ca2+ can reach up to 40 mM. A truncated version of PTH, PTH(1-34), can fully activate PTH1R and has been used for osteoporosis treatments. Here, we used fluorescence anisotropy to examine the binding of PTH(1-34) to PTH1R purified in nanodiscs (PTH1R-ND) and found that the affinity increases 5-fold in the presence of 15 mM Ca2+. However, PTHrP(1-36), another truncated endogenous agonist for PTH1R, does not show this Ca2+ effect. Mutations of Glu19 and Glu22 in PTH(1-34) that are not conserved in PTHrP(1-36) largely abolished the Ca2+ effect. The results support that PTH(1-34) not only activates PTH1R but also uniquely senses Ca2+. This dual function of a peptide hormone is a novel observation that couples changes in extracellular environment with endocrine signaling. Understanding this can potentially reveal the complex role of PTH signaling in bone remodeling and improve the PTH(1-34) treatment for osteoporosis.
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Affiliation(s)
- Kelly J. Culhane
- Department of Molecular Biophysics and Biochemistry, Yale University, 266 Whitney Ave, New Haven, Connecticut 06520, USA
| | - Morgan E. Belina
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, USA
| | - Jeremiah N. Sims
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, USA
| | - Yingying Cai
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, USA
| | - Yuting Liu
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, USA
| | - Pam S. P. Wang
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, USA
| | - Elsa C. Y. Yan
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, USA
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Subedi GP, Johnson RW, Moniz HA, Moremen KW, Barb AW. High Yield Expression of Recombinant Human Proteins with the Transient Transfection of HEK293 Cells in Suspension. J Vis Exp 2015:e53568. [PMID: 26779721 PMCID: PMC4780855 DOI: 10.3791/53568] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The art of producing recombinant proteins with complex post-translational modifications represents a major challenge for studies of structure and function. The rapid establishment and high recovery from transiently-transfected mammalian cell lines addresses this barrier and is an effective means of expressing proteins that are naturally channeled through the ER and Golgi-mediated secretory pathway. Here is one protocol for protein expression using the human HEK293F and HEK293S cell lines transfected with a mammalian expression vector designed for high protein yields. The applicability of this system is demonstrated using three representative glycoproteins that expressed with yields between 95-120 mg of purified protein recovered per liter of culture. These proteins are the human FcγRIIIa and the rat α2-6 sialyltransferase, ST6GalI, both expressed with an N-terminal GFP fusion, as well as the unmodified human immunoglobulin G1 Fc. This robust system utilizes a serum-free medium that is adaptable for expression of isotopically enriched proteins and carbohydrates for structural studies using mass spectrometry and nuclear magnetic resonance spectroscopy. Furthermore, the composition of the N-glycan can be tuned by adding a small molecule to prevent certain glycan modifications in a manner that does not reduce yield.
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Affiliation(s)
- Ganesh P Subedi
- The Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University
| | - Roy W Johnson
- Complex Carbohydrate Research Center, University of Georgia
| | | | | | - Adam W Barb
- The Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University;
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Almo SC, Love JD. Better and faster: improvements and optimization for mammalian recombinant protein production. Curr Opin Struct Biol 2014; 26:39-43. [PMID: 24721463 DOI: 10.1016/j.sbi.2014.03.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 03/04/2014] [Accepted: 03/10/2014] [Indexed: 11/18/2022]
Abstract
Thanks to numerous technological advances, the production of recombinant proteins in mammalian cell lines has become an increasingly routine task that is no longer viewed as a heroic enterprise. While production in prokaryotic or lower eukaryotic systems may be more rapid and economical, the advantages of producing large amounts of protein that closely resembles the native form is often advantageous and may be essential for the realization of functionally active material for biological studies or biopharmaceuticals. The correct folding, processing and post-translational modifications conferred by expression in a mammalian cell is relevant to all classes of proteins, including cytoplasmic, secreted or integral membrane proteins. Therefore considerable efforts have focused on the development of growth media, cell lines, transformation methods and selection techniques that enable the production of grams of functional protein in weeks, rather than months. This review will focus on a plethora of methods that are broadly applicable to the high yield production of any class of protein (cytoplasmic, secreted or integral membrane) from mammalian cells.
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Affiliation(s)
- Steven C Almo
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, United States
| | - James D Love
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, United States.
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Wu L, Zhai Y, Lu J, Wang Q, Sun F. Expression, purification and preliminary characterization of glucagon receptor extracellular domain. Protein Expr Purif 2013; 89:232-40. [DOI: 10.1016/j.pep.2013.04.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Revised: 04/05/2013] [Accepted: 04/06/2013] [Indexed: 12/13/2022]
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Hunt BD, Ng LL, Lambert DG. In vitro siRNA-mediated knockdown of the UT receptor: implications of density on the efficacy of a range of UT ligands. Naunyn Schmiedebergs Arch Pharmacol 2012; 385:651-6. [PMID: 22315015 DOI: 10.1007/s00210-012-0728-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 01/09/2012] [Indexed: 11/29/2022]
Abstract
Urotensin-II (U-II) is the peptide agonist for the U-II receptor (UT). Putative UT antagonists, urantide and UFP-803, have been found to have variable efficacy in a range of assays. We have used siRNA-mediated RNA interference to probe the efficacy of these ligands compared to U-II. Knockdown of human UT occurs in the same cellular background with the same coupling machinery allowing relative efficacy to be probed. CHO cells stably expressing 1,110 fmol/mg protein of human UT (CHOhUT) were transfected with s194454, s194455 (UT-targeting), or a negative control siRNA using siPORT amine transfection reagent. After 48 h,silencing was assessed using quantitative PCR in a duplex assay format. Functional consequences of silencing were assessed by measuring [Ca2+]i in Fura-2 loaded cells using the NOVOstar plate reader. Silencing with s194455 was greater than that with s194454 (93.5±2.8% and 73.0±2.5%knockdown of UT mRNA respectively at 10−7 M, p00.006).Both s194455 and s194454 knocked down UT mRNA expression with equal potency (EC50 1.38 and 0.45 nM). The negative control did not affect UT mRNA expression. U-II(10−6M) increased [Ca2+]i 630±69, 402±49 and 190±14nM,urantide (10−6 M) increased [Ca2+]i 408±55, 191±40, and 131±10 nM and UFP-803 (10−6 M) increased [Ca2+]i 134±23, 83±11 and 53±3nM for negative control siRNA, s194454 and s194455, respectively.We have demonstrated silencing of UT mRNA and a reduction of absolute efficacy of three UT ligands. However, we were unable to resolve any changes in relative efficacy for urantide and UFP-803. This is likely to result from a high starting expression and retention of a receptor/coupling reserve.
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Affiliation(s)
- Benjamin D Hunt
- University Department of Cardiovascular Sciences (Pharmacology and Therapeutics Group) and Leicester NIHR Cardiovascular Biomedical Research Unit, Division of Anaesthesia, Critical Care and Pain Management,University of Leicester, Leicester Royal Infirmary, Leicester, UK
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Abstract
The number of structures of integral membrane proteins from higher eukaryotes is steadily increasing due to a number of innovative protein engineering and crystallization strategies devised over the last few years. However, it is sobering to reflect that these structures represent only a tiny proportion of the total number of membrane proteins encoded by a mammalian genome. In addition, the structures determined to date are of the most tractable membrane proteins, i.e., those that are expressed functionally and to high levels in yeast or in insect cells using the baculovirus expression system. However, some membrane proteins that are expressed inefficiently in these systems can be produced at sufficiently high levels in mammalian cells to allow structure determination. Mammalian expression systems are an under-used resource in structural biology and represent an effective way to produce fully functional membrane proteins for structural studies. This review will discuss examples of vertebrate membrane protein overexpression in mammalian cells using a variety of viral, constitutive or inducible expression systems.
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Affiliation(s)
- Juni Andréll
- MRC Laboratory of Molecular Biology, Cambridge, UK
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Gier B, Butler PC, Lai CK, Kirakossian D, DeNicola MM, Yeh MW. Glucagon like peptide-1 receptor expression in the human thyroid gland. J Clin Endocrinol Metab 2012; 97:121-31. [PMID: 22031513 PMCID: PMC3412261 DOI: 10.1210/jc.2011-2407] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
BACKGROUND Glucagon like peptide-1 (GLP-1) mimetic therapy induces medullary thyroid neoplasia in rodents. We sought to establish whether C cells in human medullary thyroid carcinoma, C cell hyperplasia, and normal human thyroid express the GLP-1 receptor. METHODS Thyroid tissue samples with medullary thyroid carcinoma (n = 12), C cell hyperplasia (n = 9), papillary thyroid carcinoma (n = 17), and normal human thyroid (n = 15) were evaluated by immunofluorescence for expression of calcitonin and GLP-1 receptors. RESULTS Coincident immunoreactivity for calcitonin and GLP-1 receptor was consistently observed in both medullary thyroid carcinoma and C cell hyperplasia. GLP-1 receptor immunoreactivity was also detected in 18% of papillary thyroid carcinoma (three of 17 cases). Within normal human thyroid tissue, GLP-1 receptor immunoreactivity was found in five of 15 of the examined cases in about 35% of the total C cells assessed. CONCLUSIONS In humans, neoplastic and hyperplastic lesions of thyroid C cells express the GLP-1 receptor. GLP-1 receptor expression is detected in 18% papillary thyroid carcinomas and in C cells in 33% of control thyroid lobes. The consequence of long-term pharmacologically increased GLP-1 signaling on these GLP-1 receptor-expressing cells in the thyroid gland in humans remains unknown, but appropriately powered prospective studies to exclude an increase in medullary or papillary carcinomas of the thyroid are warranted.
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Affiliation(s)
- Belinda Gier
- Larry L. Hillblom Islet Research Center, David Geffen School of Medicine at the University of California, Los Angeles, 10833 Le Conte Avenue 72-228 CHS, Los Angeles, California 90095-6904, USA
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Krilov L, Nguyen A, Miyazaki T, Unson CG, Williams R, Lee NH, Ceryak S, Bouscarel B. Dual mode of glucagon receptor internalization: role of PKCα, GRKs and β-arrestins. Exp Cell Res 2011; 317:2981-94. [PMID: 22001118 DOI: 10.1016/j.yexcr.2011.10.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 09/29/2011] [Accepted: 10/01/2011] [Indexed: 10/17/2022]
Abstract
Glucagon levels are elevated in diabetes and some liver diseases. Increased glucagon secretion leads to abnormal stimulation of glucagon receptors (GRs) and consequent elevated glucose production in the liver. Blocking glucagon receptor signaling has been proposed as a potential treatment option for diabetes and other conditions associated with hyperglycemia. Elucidating mechanisms of GR desensitization and downregulation may help identify new drug targets besides GR itself. The present study explores the mechanisms of GR internalization and the role of PKCα, GPCR kinases (GRKs) and β-arrestins therein. We have reported previously that PKCα mediates GR phosphorylation and desensitization. While the PKC agonist, PMA, did not affect GR internalization when tested alone, it increased glucagon-mediated GR internalization by 25-40% in GR-expressing HEK-293 cells (HEK-GR cells). In both primary hepatocytes and HEK-GR cells, glucagon treatment recruited PKCα to the plasma membrane where it colocalized with GR. We also observed that overexpression of GRK2, GRK3, or GRK5 enhanced GR internalization. In addition, we found that GR utilizes both clathrin- and caveolin-mediated endocytosis in HEK-GR cells. Glucagon triggered translocation of both β-arrestin1 and β-arrestin2 from the cytosol to the perimembrane region, and overexpression of β-arrestin1 and β-arrestin2 increased GR internalization. Furthermore, both β-arrestin1 and β-arrestin2 colocalized with GR and with Cav-1, suggesting the possible involvement of these arrestins in GR internalization.
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Affiliation(s)
- Lada Krilov
- Gastroenterology Research Laboratory, Digestive Diseases Center, Department of Biochemistry and Molecular Biology, The George Washington University, Washington, DC, USA
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Krilov L, Nguyen A, Miyazaki T, Unson CG, Bouscarel B. Glucagon receptor recycling: role of carboxyl terminus, beta-arrestins, and cytoskeleton. Am J Physiol Cell Physiol 2008; 295:C1230-7. [PMID: 18787074 DOI: 10.1152/ajpcell.00240.2008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Glucagon receptor (GR) activity and expression are altered in several diseases, including Type 2 diabetes. Previously, we investigated the mechanism of GR desensitization and internalization. The present study focused on the fate of internalized GR. Using both hamster hepatocytes and human embryonic kidney (HEK)-293 cells, we showed that internalized GR recycled to the plasma membrane within 30-60 min following stimulation of the cells with 100 nM glucagon. In HEK-293 cells and during recycling, GR colocalized with Rab4, Rab11, beta-arrestin1, beta-arrestin2, and actin filaments, in the cytosolic and/or perinuclear domains. Glucagon treatment triggered redistribution of actin filaments from the plasma membrane to the cytosol. GR coimmunoprecipitated with beta-actin in both hepatocytes and HEK-293 cells. Downregulation of beta-arrestin1 and beta-arrestin2 or disruption of the cytoskeleton inhibited recycling, but not internalization of GR. Deletion of the GR carboxyl-terminal 70 amino acids abolished internalization of GR in response to glucagon while deletion of the last 40 amino acids only did not affect GR internalization and recycling. After exposure of the cells to either high concentrations or prolonged duration of glucagon, GR colocalized with lysosomes. GR degradation was inhibited by lysosomal, but not proteosomal, inhibitors. In conclusion, GR recycles through Rab4- and Rab11- positive vesicles. The actin cytoskeleton, beta-arrestin1, beta-arrestin2, and the receptor's carboxyl terminus are involved in recycling. Prolonged stimulation with glucagon targets GR for degradation in lysosomes. Therefore, the present study provides a better understanding of the GR recycling mechanism, which could become useful in the treatment of certain diseases, including diabetes.
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Affiliation(s)
- Lada Krilov
- Gastroenterology Research Laboratory. Digestive Diseases Center, Dept. of Biochemistry and Molecular Biology, George Washington Univ., 2300 Eye St. NW, Washington, DC 20037, USA
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