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Foust DJ, Piston DW. Measuring G protein activation by spectrally resolved imaging fluorescence fluctuation spectroscopy. Biophys J 2024:S0006-3495(24)00552-6. [PMID: 39148292 DOI: 10.1016/j.bpj.2024.08.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 06/21/2024] [Accepted: 08/12/2024] [Indexed: 08/17/2024] Open
Abstract
The activation of heterotrimeric G proteins through G-protein-coupled receptors (GPCRs) is a ubiquitous signaling mechanism in eukaryotic biology. The three principal molecular components of this cascade are the GPCR, Gα subunit, and Gβγ subunit. Measurement of interactions between these components and their downstream effectors in live cells is paramount to understanding how cells fine-tune their physiology in response to many external stimuli. Multicolor fluorescence fluctuation spectroscopy (FFS) approaches allow the sensitive detection of heteromeric interactions by using spectrally distinct fluorophores to label biomolecules of interest. We considered three imaging FFS approaches to measuring molecular interactions from the signals produced by a spectrally resolved confocal microscopy: raster spectral image correlation spectroscopy (RSICS), spectral spatial cumulant analysis, and native resolution spatial cumulant analysis. We characterized these approaches using simulation and experiments on heteromers with known stoichiometries. We found that RSICS had the best sensitivity for measuring heteromeric interactions and employed it to measure G protein complexes. As measured by RSICS, interactions between the G protein subunits Gαi1 and Gβ1γ2 were sensitive to the stimulation of two GPCRs, the D2 dopamine receptor and the α-2A adrenergic receptor. Interactions between GPCRs and G proteins were not detectable above background, supporting a collisional model of GPCR/G protein interactions in contrast to a preassembly model where strong interactions would be present. These data are uniquely available by this FFS framework, which is appropriate for not only multiplexed measurements of G protein biology but any dynamic protein complexes in the cell.
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Affiliation(s)
- Daniel J Foust
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri; Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri
| | - David W Piston
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri.
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2
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Pospieszna B, Kusy K, Slominska EM, Ciekot-Sołtysiak M, Zieliński J. Sports Participation Promotes Beneficial Adaptations in the Erythrocyte Guanylate Nucleotide Pool in Male Athletes Aged 20-90 Years. Clin Interv Aging 2023; 18:987-997. [PMID: 37377627 PMCID: PMC10292611 DOI: 10.2147/cia.s406555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 05/25/2023] [Indexed: 06/29/2023] Open
Abstract
Introduction The guanine nucleotide pool (GTP, guanosine-5'-triphosphate; GDP, guanosine-5'-diphosphate, and GMP, guanosine-5'-monophosphate) is an essential energy donor in various biological processes (eg protein synthesis and gluconeogenesis) and secures several vital regulatory functions in the human body. The study aimed to predict the trends of age-related changes in erythrocyte guanine nucleotides and examine whether competitive sport and related physical training promote beneficial adaptations in erythrocyte guanylate concentrations. Methods The study included 86 elite endurance runners (EN) aged 20-81 years, 58 sprint-trained athletes (SP) aged 21-90 years, and 62 untrained individuals (CO) aged 20-68 years. Results The concentration of erythrocyte GTP and total guanine nucleotides (TGN) were highest in the SP group, lower in the EN group, and lowest in the CO group. Both athletic groups had higher guanylate energy charge (GEC) values than the CO group (p = 0.012). Concentrations of GTP, TGN, and GEC value significantly decreased, while GDP and GMP concentrations progressively increased with age. Conclusion Such a profile of change suggests a deterioration of the GTP-related regulatory function in older individuals. Our study explicitly shows that lifelong sports participation, especially of sprint-oriented nature, allows for maintaining a higher erythrocyte guanylate pool concentration, supporting cells' energy metabolism, regulatory and transcription properties, and thus more efficient overall body functioning.
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Affiliation(s)
- Barbara Pospieszna
- Department of Athletics, Strength and Conditioning, Poznan University of Physical Education, Poznan, Poland
| | - Krzysztof Kusy
- Department of Athletics, Strength and Conditioning, Poznan University of Physical Education, Poznan, Poland
| | | | - Monika Ciekot-Sołtysiak
- Department of Athletics, Strength and Conditioning, Poznan University of Physical Education, Poznan, Poland
| | - Jacek Zieliński
- Department of Athletics, Strength and Conditioning, Poznan University of Physical Education, Poznan, Poland
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3
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Cox BM, Toll L. Contributions of the International Narcotics Research Conference to Opioid Research Over the Past 50 years. ADVANCES IN DRUG AND ALCOHOL RESEARCH 2022; 2:10115. [PMID: 38390618 PMCID: PMC10880772 DOI: 10.3389/adar.2022.10115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 01/14/2022] [Indexed: 02/24/2024]
Abstract
The International Narcotics Research Conference (INRC), founded in 1969, has been a successful forum for research into the actions of opiates, with an annual conference since 1971. Every year, scientists from around the world have congregated to present the latest data on novel opiates, opiate receptors and endogenous ligands, mechanisms of analgesic activity and unwanted side effects, etc. All the important discoveries in the opiate field were discussed, often first, at the annual INRC meeting. With an apology to important events and participants not discussed, this review presents a short history of INRC with a discussion of groundbreaking discoveries in the opiate field and the researchers who presented from the first meeting up to the present.
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Affiliation(s)
- Brian M Cox
- Department of Pharmacology and Molecular Therapeutics, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Lawrence Toll
- Department of Biomedical Sciences, Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, United States
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4
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Vaghari-Tabari M, Ferns GA, Qujeq D, Andevari AN, Sabahi Z, Moein S. Signaling, metabolism, and cancer: An important relationship for therapeutic intervention. J Cell Physiol 2021; 236:5512-5532. [PMID: 33580511 DOI: 10.1002/jcp.30276] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 12/28/2020] [Accepted: 12/30/2020] [Indexed: 11/05/2022]
Abstract
In cancerous cells, significant changes occur in the activity of signaling pathways affecting a wide range of cellular activities ranging from growth and proliferation to apoptosis, invasiveness, and metastasis. Extensive changes also happen with respect to the metabolism of a cancerous cell encompassing a wide range of functions that include: nutrient acquisition, biosynthesis of macromolecules, and energy generation. These changes are important and some therapeutic approaches for treating cancers have focused on targeting the metabolism of cancerous cells. Oncogenes and tumor suppressor genes have a significant effect on the metabolism of cells. There appears to be a close interaction between metabolism and the signaling pathways in a cancerous cell, in which the interaction provides the metabolic needs of a cancerous cell for uncontrolled proliferation, resistance to apoptosis, and metastasis. In this review, we have reviewed the latest findings in this regard and briefly review the most recent research findings regarding targeting the metabolism of cancer cells as a therapeutic approach for treatment of cancer.
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Affiliation(s)
- Mostafa Vaghari-Tabari
- Department of Clinical Biochemistry and Laboratory Medicine, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.,Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Gordon A Ferns
- Department of Medical Education, Brighton & Sussex Medical School, Falmer, Brighton, Sussex, UK
| | - Durdi Qujeq
- Cellular and Molecular Biology Research Center (CMBRC), Health Research Institute, Babol University of Medical Sciences, Babol, Iran.,Department of Clinical Biochemistry, Babol University of Medical Sciences, Babol, Iran
| | - Ali Nosrati Andevari
- Department of Biochemistry, Faculty of Medicine, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
| | - Zahra Sabahi
- Medicinal Plants Processing Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Soheila Moein
- Medicinal Plants Processing Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
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Calebiro D, Koszegi Z, Lanoiselée Y, Miljus T, O'Brien S. G protein-coupled receptor-G protein interactions: a single-molecule perspective. Physiol Rev 2020; 101:857-906. [PMID: 33331229 DOI: 10.1152/physrev.00021.2020] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
G protein-coupled receptors (GPCRs) regulate many cellular and physiological processes, responding to a diverse range of extracellular stimuli including hormones, neurotransmitters, odorants, and light. Decades of biochemical and pharmacological studies have provided fundamental insights into the mechanisms of GPCR signaling. Thanks to recent advances in structural biology, we now possess an atomistic understanding of receptor activation and G protein coupling. However, how GPCRs and G proteins interact in living cells to confer signaling efficiency and specificity remains insufficiently understood. The development of advanced optical methods, including single-molecule microscopy, has provided the means to study receptors and G proteins in living cells with unprecedented spatio-temporal resolution. The results of these studies reveal an unexpected level of complexity, whereby GPCRs undergo transient interactions among themselves as well as with G proteins and structural elements of the plasma membrane to form short-lived signaling nanodomains that likely confer both rapidity and specificity to GPCR signaling. These findings may provide new strategies to pharmaceutically modulate GPCR function, which might eventually pave the way to innovative drugs for common diseases such as diabetes or heart failure.
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Affiliation(s)
- Davide Calebiro
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Nottingham and Birmingham, Birmingham, United Kingdom
| | - Zsombor Koszegi
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Nottingham and Birmingham, Birmingham, United Kingdom
| | - Yann Lanoiselée
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Nottingham and Birmingham, Birmingham, United Kingdom
| | - Tamara Miljus
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Nottingham and Birmingham, Birmingham, United Kingdom
| | - Shannon O'Brien
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Nottingham and Birmingham, Birmingham, United Kingdom
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Li J, Ge Y, Huang JX, Strømgaard K, Zhang X, Xiong XF. Heterotrimeric G Proteins as Therapeutic Targets in Drug Discovery. J Med Chem 2019; 63:5013-5030. [PMID: 31841625 DOI: 10.1021/acs.jmedchem.9b01452] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Heterotrimeric G proteins are molecular switches in GPCR signaling pathways and regulate a plethora of physiological and pathological processes. GPCRs are efficient drug targets, and more than 30% of the drugs in use target them. However, selectively targeting an individual GPCR may be undesirable in various multifactorial diseases in which multiple receptors are involved. In addition, abnormal activation or expression of G proteins is frequently associated with diseases. Furthermore, G proteins harboring mutations often result in malignant diseases. Thus, targeting G proteins instead of GPCRs might provide alternative approaches for combating these diseases. In this review, we discuss the biochemistry of heterotrimeric G proteins, describe the G protein-associated diseases, and summarize the currently known modulators that can regulate the activities of G proteins. The outlook for targeting G proteins to treat diverse diseases is also included in this manuscript.
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Affiliation(s)
- Jian Li
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, 510006 Guangzhou, Guangdong, P. R. China
| | - Yang Ge
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, 510006 Guangzhou, Guangdong, P. R. China
| | - Jun-Xiang Huang
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, 510006 Guangzhou, Guangdong, P. R. China
| | - Kristian Strømgaard
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Xiaolei Zhang
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, 510006 Guangzhou, Guangdong, P. R. China
| | - Xiao-Feng Xiong
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, 510006 Guangzhou, Guangdong, P. R. China
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Kurtul N, Pençe S, Akarsu E, Koçoğlu H, Aksoy Y, Aksoy H. Adenosine Deaminase Activity in the Serum of Type 2 Diabetic Patients. ACTA MEDICA (HRADEC KRÁLOVÉ) 2019. [DOI: 10.14712/18059694.2018.63] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Adenosine deaminase (ADA) is suggested to be an important enzyme for modulating the bioactivity of insulin, but its clinical significance in diabetes mellitus (DM) is not yet characterized. We measured the serum level of ADA in healthy controls (C, n=29) and type 2 diabetic patients (n=42). The mean serum level of ADA in C, and type 2 diabetic patients were 29.81±9.15 and. 20.73±8.42 U/L, respectively (P<0.006 vs. C). ADA levels of patients were significantly correlated with HbA1c (r=0.45, p<0.01). Our findings suggest that ADA may play a role in insulin effect and glycamic control. On the other hand, increased activity of ADA in type 2 DM might be a marker for insulin indication. However, further studies are required for the pathogenic role of elevated ADA activity in type 2 DM.
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Quitterer U, AbdAlla S. Discovery of Pathologic GPCR Aggregation. Front Med (Lausanne) 2019; 6:9. [PMID: 30761305 PMCID: PMC6363654 DOI: 10.3389/fmed.2019.00009] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 01/14/2019] [Indexed: 01/02/2023] Open
Abstract
The family of G-protein-coupled receptors (GPCRs) is one of the most important drug targets. Mechanisms underlying GPCR activation and signaling are therefore of great pharmacologic interest. It was long thought that GPCRs exist and function as monomers. This feature was considered to distinguish GPCRs from other membrane receptors such as receptor tyrosine kinases or cytokine receptors, which signal from dimeric receptor complexes. But during the last two decades it was increasingly recognized that GPCRs can undergo aggregation to form dimers and higher order oligomers, resulting in homomeric and/or heteromeric protein complexes with different stoichiometries. Moreover, this protein complex formation could modify GPCR signaling and function. We contributed to this paradigm shift in GPCR pharmacology by the discovery of the first pathologic GPCR aggregation, which is the protein complex formation between the angiotensin II AT1 receptor and the bradykinin B2 receptor. Increased AT1-B2 heteromerization accounts for the angiotensin II hypersensitivity of pregnant women with preeclampsia hypertension. Since the discovery of AT1-B2, other pathologic GPCR aggregates were found, which contribute to atherosclerosis, neurodegeneration and Alzheimer's disease. As a result of our findings, pathologic GPCR aggregation appears as an independent and disease-specific process, which is increasingly considered as a novel target for pharmacologic intervention.
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Affiliation(s)
- Ursula Quitterer
- Molecular Pharmacology, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland.,Department of Medicine, Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Said AbdAlla
- Molecular Pharmacology, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland
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Mao X, Xu Y, Jiang Z. HColonDB: A Database for Human Colon Cancer Research. J Comput Biol 2019; 26:218-224. [PMID: 30614735 DOI: 10.1089/cmb.2018.0193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
HColonDB (Human Colon cancer Database) is an important database which integrates genes, pathways, networks, drugs, and other information related to colon cancer. The purpose of the database is to provide a platform for the systematic research of colon cancer. The relationships between genes and pathways, genes and networks, and networks and pathways are obtained from the database KEGG. Furthermore, the information of the drugs used to treat colon cancer is available in HColonDB, which is collected and organized from DrugBank and PubChem database. In brief, we have summarized 81 genes, 112 pathways, 108 networks, and 15 drugs associated with colon cancer. The current version of HColonDB contains 322 associations between genes and pathways, 242 associations between genes and networks, and 68 associations between networks and pathways. In addition, HColonDB provides a friendly interface for users to browse and search. We hope that the database can make it more convenient for researchers to get the data they need and help in the treatment of colon cancer.
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Affiliation(s)
- Xiaodan Mao
- Department of Computer Science and Technology, East China Normal University , Shanghai, China
| | - Yichen Xu
- Department of Computer Science and Technology, East China Normal University , Shanghai, China
| | - Zhenran Jiang
- Department of Computer Science and Technology, East China Normal University , Shanghai, China
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10
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Ostadal B, Parizek A, Ostadalova I, Kolar F. Cardiotoxicity of β-mimetic catecholamines during ontogenetic development - possible risks of antenatal therapy. Can J Physiol Pharmacol 2018; 96:639-646. [PMID: 29633627 DOI: 10.1139/cjpp-2017-0774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Catecholamines are involved in the regulation of a wide variety of vital functions. The β-adrenergic receptor (β-AR) - adenylyl cyclase system has been identified early in embryogenesis before the heart has received adrenergic innervation. The structure of β-receptors in the immature myocardium is similar to that in adults; there are, however, significant quantitative developmental changes in the inotropic and chronotropic responsiveness. Information on the toxic effect of the β-AR agonists in the immature heart is surprisingly scarce, even though these agents are used in clinical practice both during pregnancy and in early postnatal development. Large doses of β-AR agonists induce malformations of the cardiovascular system; the type of change depends upon the time at which the β-AR agonist was administered during embryogenesis. During postnatal ontogeny, the cardiotoxicity of β-AR agonists increased from birth to adulthood. It seems likely that despite interspecies differences, developmental changes in the cardiac sensitivity to β-AR agonists may exist in all mammals, depending on the degree of maturation of the system involved in β-adrenergic signaling. All the existing data draw attention to the possible harmful consequences of the clinical use of β-AR agonists during early phases of cardiac development. Late effects of the early disturbances of the cardiac muscle cannot be excluded.
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Affiliation(s)
- B Ostadal
- a Institute of Physiology, Czech Academy of Sciences, Videnska 1083, 14220 Prague 4, Czech Republic
| | - A Parizek
- b Department of Obstetrics and Gynecology, 1st Faculty of Medicine, Charles University and General Faculty Hospital, Prague, Czech Republic
| | - I Ostadalova
- a Institute of Physiology, Czech Academy of Sciences, Videnska 1083, 14220 Prague 4, Czech Republic
| | - F Kolar
- a Institute of Physiology, Czech Academy of Sciences, Videnska 1083, 14220 Prague 4, Czech Republic
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Adenylate Cyclases of Trypanosoma brucei, Environmental Sensors and Controllers of Host Innate Immune Response. Pathogens 2018; 7:pathogens7020048. [PMID: 29693583 PMCID: PMC6027212 DOI: 10.3390/pathogens7020048] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/12/2018] [Accepted: 04/20/2018] [Indexed: 12/12/2022] Open
Abstract
Trypanosoma brucei, etiological agent of Sleeping Sickness in Africa, is the prototype of African trypanosomes, protozoan extracellular flagellate parasites transmitted by saliva (Salivaria). In these parasites the molecular controls of the cell cycle and environmental sensing are elaborate and concentrated at the flagellum. Genomic analyses suggest that these parasites appear to differ considerably from the host in signaling mechanisms, with the exception of receptor-type adenylate cyclases (AC) that are topologically similar to receptor-type guanylate cyclase (GC) of higher eukaryotes but control a new class of cAMP targets of unknown function, the cAMP response proteins (CARPs), rather than the classical protein kinase A cAMP effector (PKA). T. brucei possesses a large polymorphic family of ACs, mainly associated with the flagellar membrane, and these are involved in inhibition of the innate immune response of the host prior to the massive release of immunomodulatory factors at the first peak of parasitemia. Recent evidence suggests that in T. brucei several insect-specific AC isoforms are involved in social motility, whereas only a few AC isoforms are involved in cytokinesis control of bloodstream forms, attesting that a complex signaling pathway is required for environmental sensing. In this review, after a general update on cAMP signaling pathway and the multiple roles of cAMP, I summarize the existing knowledge of the mechanisms by which pathogenic microorganisms modulate cAMP levels to escape immune defense.
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Gao J, Gu Z, Li M, Xu Y, Gao Y, Wei J, Liang B, Na Y. L-Carnitine Ameliorates the Decrease of Aquaporin 2 Levels in Rats with Cisplatin-Induced Kidney Injury. Nephron Clin Pract 2017; 135:315-325. [PMID: 28161696 DOI: 10.1159/000455052] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 11/22/2016] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND It has been found that L-carnitine ameliorated cisplatin-induced acute kidney injury (AKI) in rats. However, the detailed role of L-carnitine in improving the renal urinary concentration function in cisplatin-induced AKI is not fully understood. METHODS In this study, 30 Sprague-Dawley rats were divided randomly into 5 groups: control, cisplatin (CIS), L-carnitine (CAR), L-carnitine plus cisplatin (CAR + CIS), and cisplatin plus L-carnitine (CIS + CAR) groups. Cisplatin (7 mg/kg) and L-carnitine (300 mg/kg) were injected intraperitoneally. Urine (24 h) and blood samples were collected to analyze renal urinary concentrating function. Immunoblotting, confocal laser microscopy, and enzyme-linked immunosorbent assays were used to assess the level and localization of the water channel aquaporin (AQP) 2, and levels of stimulatory G protein α subunit (GSα protein), arginine vasopressin (AVP) receptor 2, adenylyl cyclase and serum AVP. RESULTS Renal urinary concentrating function was improved by L-carnitine in rats with cisplatin-induced AKI. AQP2 expression, which decreased after cisplatin treatment, was improved by L-carnitine in different regions of the kidney. Moreover, our data indicated that L-carnitine could increase AQP2 accumulation at the apical plasma membranes of the renal-collecting ducts. Finally, intervention with L-carnitine effectively improved the expression of AQP2 upstream signaling proteins, such as GSα protein, adenylyl cyclase, and serum AVP levels in rats with cisplatin-induced AKI. CONCLUSION L-carnitine resolves the cisplatin-induced urinary concentration defect, which may occur by increasing AVP/cyclic adenosine monophosphate/AQP2 levels, indicating the potential use of L-carnitine to ameliorate the renal urinary concentration effect in cancer patients treated with cisplatin.
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Affiliation(s)
- Jianjun Gao
- Department of Nephrology, The 306th Hospital of Chinese PLA, Beijing, China
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Liu TCY, Liu G, Hu SJ, Zhu L, Yang XB, Zhang QG. Quantitative Biology of Exercise-Induced Signal Transduction Pathways. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 977:419-424. [PMID: 28685473 DOI: 10.1007/978-3-319-55231-6_54] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
UNLABELLED Exercise is essential in regulating energy metabolism. Exercise activates cellular, molecular, and biochemical pathways with regulatory roles in training response adaptation. Among them, endurance/strength training of an individual has been shown to activate its respective signal transduction pathways in skeletal muscle. This was further studied from the viewpoint of quantitative difference (QD). For the mean values, [Formula: see text], of two sets of data, their QD is defined as [Formula: see text] ([Formula: see text]). The function-specific homeostasis (FSH) of a function of a biosystem is a negative-feedback response of the biosystem to maintain the function-specific conditions inside the biosystem so that the function is perfectly performed. A function in/far from its FSH is called a normal/dysfunctional function. A cellular normal function can resist the activation of other signal transduction pathways so that there are normal function-specific signal transduction pathways which full activation maintains the normal function. RESULTS An acute endurance/strength training may be dysfunctional, but its regular training may be normal. The normal endurance/strength training of an individual may resist the activation of other signal transduction pathways in skeletal muscle so that there may be normal endurance/strength training-specific signal transduction pathways (NEPs/NSPs) in skeletal muscle. The endurance/strength training may activate NSPs/NEPs, but the QD from the control is smaller than 0.80. The simultaneous activation of both NSPs and NEPs may enhance their respective activation, and the QD from the control is larger than 0.80. The low level laser irradiation pretreatment of rats may promote the activation of NSPs in endurance training skeletal muscle. CONCLUSION There may be NEPs/NSPs in skeletal muscle trained by normal endurance/strength training.
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Affiliation(s)
- Timon Cheng-Yi Liu
- Laboratory of Laser Sports Medicine, South China Normal University, Guangzhou, China.
| | - Gang Liu
- Sports and Health College, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Shao-Juan Hu
- Laboratory of Laser Sports Medicine, South China Normal University, Guangzhou, China
| | - Ling Zhu
- Laboratory of Laser Sports Medicine, South China Normal University, Guangzhou, China
| | - Xiang-Bo Yang
- Laboratory of Laser Sports Medicine, South China Normal University, Guangzhou, China
| | - Quan-Guang Zhang
- Laboratory of Laser Sports Medicine, South China Normal University, Guangzhou, China
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Push-Pull and Feedback Mechanisms Can Align Signaling System Outputs with Inputs. Cell Syst 2016; 3:444-455.e2. [PMID: 27894998 DOI: 10.1016/j.cels.2016.10.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 06/10/2016] [Accepted: 10/04/2016] [Indexed: 11/23/2022]
Abstract
Many cell signaling systems, including the yeast pheromone response system, exhibit "dose-response alignment" (DoRA), in which output of one or more downstream steps closely matches the fraction of occupied receptors. DoRA can improve the fidelity of transmitted dose information. Here, we searched systematically for biochemical network topologies that produced DoRA. Most networks, including many containing feedback and feedforward loops, could not produce DoRA. However, networks including "push-pull" mechanisms, in which the active form of a signaling species stimulates downstream activity and the nominally inactive form reduces downstream activity, enabled perfect DoRA. Networks containing feedbacks enabled DoRA, but only if they also compared feedback to input and adjusted output to match. Our results establish push-pull as a non-feedback mechanism to align output with variable input and maximize information transfer in signaling systems. They also suggest genetic approaches to determine whether particular signaling systems use feedback or push-pull control.
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Liu AP. Biophysical Tools for Cellular and Subcellular Mechanical Actuation of Cell Signaling. Biophys J 2016; 111:1112-1118. [PMID: 27456131 DOI: 10.1016/j.bpj.2016.02.043] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 01/17/2016] [Accepted: 02/01/2016] [Indexed: 10/24/2022] Open
Abstract
The ability to spatially control cell signaling can help resolve fundamental biological questions. Optogenetic and chemical dimerization techniques along with fluorescent biosensors to report cell signaling activities have enabled researchers to both visualize and perturb biochemistry in living cells. A number of approaches based on mechanical actuation using force-field gradients have emerged as complementary technologies to manipulate cell signaling in real time. This review covers several technologies, including optical, magnetic, and acoustic control of cell signaling and behavior and highlights some studies that have led to novel insights. I will also discuss some future direction on repurposing mechanosensitive channel for mechanical actuation of spatial cell signaling.
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Affiliation(s)
- Allen P Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan; Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan; Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, Michigan; Biophysics Program, University of Michigan, Ann Arbor, Michigan.
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16
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Ferrari S, Gentili C. Maintaining Genome Stability in Defiance of Mitotic DNA Damage. Front Genet 2016; 7:128. [PMID: 27493659 PMCID: PMC4954828 DOI: 10.3389/fgene.2016.00128] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 07/06/2016] [Indexed: 01/08/2023] Open
Abstract
The implementation of decisions affecting cell viability and proliferation is based on prompt detection of the issue to be addressed, formulation and transmission of a correct set of instructions and fidelity in the execution of orders. While the first and the last are purely mechanical processes relying on the faithful functioning of single proteins or macromolecular complexes (sensors and effectors), information is the real cue, with signal amplitude, duration, and frequency ultimately determining the type of response. The cellular response to DNA damage is no exception to the rule. In this review article we focus on DNA damage responses in G2 and Mitosis. First, we set the stage describing mitosis and the machineries in charge of assembling the apparatus responsible for chromosome alignment and segregation as well as the inputs that control its function (checkpoints). Next, we examine the type of issues that a cell approaching mitosis might face, presenting the impact of post-translational modifications (PTMs) on the correct and timely functioning of pathways correcting errors or damage before chromosome segregation. We conclude this essay with a perspective on the current status of mitotic signaling pathway inhibitors and their potential use in cancer therapy.
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Affiliation(s)
- Stefano Ferrari
- Institute of Molecular Cancer Research, University of Zurich Zurich, Switzerland
| | - Christian Gentili
- Institute of Molecular Cancer Research, University of Zurich Zurich, Switzerland
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Barak LS, Bai Y, Peterson S, Evron T, Urs NM, Peddibhotla S, Hedrick MP, Hershberger P, Maloney PR, Chung TD, Rodriguiz RM, Wetsel WC, Thomas JB, Hanson GR, Pinkerton AB, Caron MG. ML314: A Biased Neurotensin Receptor Ligand for Methamphetamine Abuse. ACS Chem Biol 2016; 11:1880-90. [PMID: 27119457 DOI: 10.1021/acschembio.6b00291] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Pharmacological treatment for methamphetamine addiction will provide important societal benefits. Neurotensin receptor NTR1 and dopamine receptor distributions coincide in brain areas regulating methamphetamine-associated reward, and neurotensin peptides produce behaviors opposing psychostimulants. Therefore, undesirable methamphetamine-associated activities should be treatable with druggable NTR1 agonists, but no such FDA-approved therapeutics exist. We address this limitation with proof-of-concept data for ML314, a small-molecule, brain penetrant, β-arrestin biased, NTR1 agonist. ML314 attenuates amphetamine-like hyperlocomotion in dopamine transporter knockout mice, and in C57BL/6J mice it attenuates methamphetamine-induced hyperlocomotion, potentiates the psychostimulant inhibitory effects of a ghrelin antagonist, and reduces methamphetamine-associated conditioned place preference. In rats, ML314 blocks methamphetamine self-administration. ML314 acts as an allosteric enhancer of endogenous neurotensin, unmasking stoichiometric numbers of hidden NTR1 binding sites in transfected-cell membranes or mouse striatal membranes, while additionally supporting NTR1 endocytosis in cells in the absence of NT peptide. These results indicate ML314 is a viable, preclinical lead for methamphetamine abuse treatment and support an allosteric model of G protein-coupled receptor signaling.
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Affiliation(s)
- Larry S. Barak
- Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Yushi Bai
- Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Sean Peterson
- Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Tama Evron
- Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Nikhil M. Urs
- Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Satyamaheshwar Peddibhotla
- Conrad Prebys Center for Chemical Genomics at Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida 32827, United States
| | - Michael P. Hedrick
- Conrad Prebys Center for Chemical Genomics at Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037, United States
| | - Paul Hershberger
- Conrad Prebys Center for Chemical Genomics at Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida 32827, United States
| | - Patrick R. Maloney
- Conrad Prebys Center for Chemical Genomics at Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida 32827, United States
| | - Thomas D.Y. Chung
- Conrad Prebys Center for Chemical Genomics at Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037, United States
| | | | - William C. Wetsel
- Duke University Medical Center, Durham, North Carolina 27710, United States
| | - James B. Thomas
- RTI International, 3040 E
Cornwallis Road, Durham, North Carolina 27709, United States
| | - Glen R. Hanson
- Department
of Pharmacology and Toxicology, University of Utah, 260 S. Campus
Drive, Salt Lake City, Utah 84112, United States
| | - Anthony B. Pinkerton
- Conrad Prebys Center for Chemical Genomics at Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037, United States
| | - Marc G. Caron
- Duke University Medical Center, Durham, North Carolina 27710, United States
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18
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Ferreira MJ, Zanesco A. Heart rate variability as important approach for assessment autonomic modulation. MOTRIZ: REVISTA DE EDUCACAO FISICA 2016. [DOI: 10.1590/s1980-65742016000200001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
| | - Angelina Zanesco
- Universidade Estadual Paulista "Julio de Mesquita Filho", Brazil
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19
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Svechtarova MI, Buzzacchera I, Toebes BJ, Lauko J, Anton N, Wilson CJ. Sensor Devices Inspired by the Five Senses: A Review. ELECTROANAL 2016. [DOI: 10.1002/elan.201600047] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
| | | | - B. Jelle Toebes
- NovioSense BV; Transistorweg 5 6534 AT Nijmegen The Netherlands
| | - Jan Lauko
- NovioSense BV; Transistorweg 5 6534 AT Nijmegen The Netherlands
| | - Nicoleta Anton
- Universitatea de Medicina si Farmacie Grigore T.; Popa, Str. Universitatii nr. 16 700115 Iasi Romania
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20
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Rijal G, Li W. 3D scaffolds in breast cancer research. Biomaterials 2016; 81:135-156. [DOI: 10.1016/j.biomaterials.2015.12.016] [Citation(s) in RCA: 126] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 12/12/2015] [Accepted: 12/15/2015] [Indexed: 12/15/2022]
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21
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Solomon PM, Bryce BA, Kuroda MA, Keech R, Shetty S, Shaw TM, Copel M, Hung LW, Schrott AG, Armstrong C, Gordon MS, Reuter KB, Theis TN, Haensch W, Rossnagel SM, Miyazoe H, Elmegreen BG, Liu XH, Trolier-McKinstry S, Martyna GJ, Newns DM. Pathway to the piezoelectronic transduction logic device. NANO LETTERS 2015; 15:2391-2395. [PMID: 25793915 DOI: 10.1021/nl5046796] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The piezoelectronic transistor (PET) has been proposed as a transduction device not subject to the voltage limits of field-effect transistors. The PET transduces voltage to stress, activating a facile insulator-metal transition, thereby achieving multigigahertz switching speeds, as predicted by modeling, at lower power than the comparable generation field effect transistor (FET). Here, the fabrication and measurement of the first physical PET devices are reported, showing both on/off switching and cycling. The results demonstrate the realization of a stress-based transduction principle, representing the early steps on a developmental pathway to PET technology with potential to contribute to the IT industry.
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Affiliation(s)
- P M Solomon
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - B A Bryce
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - M A Kuroda
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
- ‡Department of Physics, Auburn University, Auburn, Alabama 36849, United States
| | - R Keech
- §Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - S Shetty
- §Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - T M Shaw
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - M Copel
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - L-W Hung
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - A G Schrott
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - C Armstrong
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - M S Gordon
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - K B Reuter
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - T N Theis
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - W Haensch
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - S M Rossnagel
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - H Miyazoe
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - B G Elmegreen
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - X-H Liu
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - S Trolier-McKinstry
- §Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - G J Martyna
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - D M Newns
- †IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
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Sensoy O, Weinstein H. A mechanistic role of Helix 8 in GPCRs: Computational modeling of the dopamine D2 receptor interaction with the GIPC1-PDZ-domain. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:976-83. [PMID: 25592838 DOI: 10.1016/j.bbamem.2014.12.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 11/15/2014] [Accepted: 12/02/2014] [Indexed: 01/18/2023]
Abstract
Helix-8 (Hx8) is a structurally conserved amphipathic helical motif in class-A GPCRs, adjacent to the C-terminal sequence that is responsible for PDZ-domain-recognition. The Hx8 segment in the dopamine D2 receptor (D2R) constitutes the C-terminal segment and we investigate its role in the function of D2R by studying the interaction with the PDZ-containing GIPC1 using homology models based on the X-ray structures of very closely related analogs: the D3R for the D2R model, and the PDZ domain of GIPC2 for GIPC1-PDZ. The mechanism of this interaction was investigated with all-atom unbiased molecular dynamics (MD) simulations that reveal the role of the membrane in maintaining the helical fold of Hx8, and with biased MD simulations to elucidate the energy drive for the interaction with the GIPC1-PDZ. We found that it becomes more favorable energetically for Hx8 to adopt the extended conformation observed in all PDZ-ligand complexes when it moves away from the membrane, and that C-terminus palmitoylation of D2R enhanced membrane penetration by the Hx8 backbone. De-palmitoylation enables Hx8 to move out into the aqueous environment for interaction with the PDZ domain. All-atom unbiased MD simulations of the full D2R-GIPC1-PDZ complex in sphingolipid/cholesterol membranes show that the D2R carboxyl C-terminus samples the region of the conserved GFGL motif located on the carboxylate-binding loop of the GIPC1-PDZ, and the entire complex distances itself from the membrane interface. Together, these results outline a likely mechanism of Hx8 involvement in the interaction of the GPCR with PDZ-domains in the course of signaling.
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Affiliation(s)
- Ozge Sensoy
- Department of Physiology and Biophysics, Weill Medical College of Cornell University, New York, NY, USA
| | - Harel Weinstein
- Department of Physiology and Biophysics, Weill Medical College of Cornell University, New York, NY, USA.
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23
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Perdomo D, Möller C, Bubis J. Correlation of transducin photoaffinity labeling with the specific formation of intermolecular disulfide linkages in its α-subunit. Biochimie 2014; 108:120-32. [PMID: 25450251 DOI: 10.1016/j.biochi.2014.11.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 11/08/2014] [Indexed: 11/28/2022]
Abstract
Transducin (T) is a heterotrimer of Tα, Tβ, and Tγ subunits. In the presence of light-activated rhodopsin, 8-azidoguanosine triphosphate (8-N3GTP) was covalently incorporated into T in a UV-light photodependent manner, with a low stoichiometry of 0.02 mol of 8-N3GTP per mol of T. Although Tα was preferentially labeled by 8-N3GTP, Tβ and Tγ were also modified. Photolabeling of T was specifically inhibited by GDP and GTP, but not by β,γ-imido-guanosine 5'-triphosphate (GMP-PNP), indicating that 8-N3GTP was modifying the GDP binding site of the holoenzyme. This was consistent with the observation that the photoaffinity probe was completely hydrolyzed to 8-N3GDP by T activated by illuminated rhodopsin. The formation of intermolecular disulfide associations in T was also determined because photolabeling of T was performed under non-reducing conditions. We established that Cys-347 of Tα was the major residue involved in the formation of disulfide-linked T oligomers. Other cysteines of Tα, such as Cys-321, also participated in the formation of disulfide bonds, revealing a complex pattern of intermolecular disulfide cross-links that led to the polymerization of T. The spontaneous generation of these cystines in Tα inhibited the light-dependent GTPase and GMP-PNP binding activities of T. A model was constructed illustrating that when two heterotrimers dimerize through the formation of disulfide bridges between the Cys-347 of their Tα subunits, the guanine ring of the 8-N3GDP bound to one T molecule might approach to the Tβγ-complex of the other heterotrimer. This model provides an explanation for the additional photolabeling of Tβ and Tγ by 8-N3GTP.
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Affiliation(s)
- Deisy Perdomo
- Departamento de Biología Celular, Universidad Simón Bolívar, Apartado 89.000, Valle de Sartenejas, Caracas 1081-A, Venezuela.
| | - Carolina Möller
- Departamento de Biología Celular, Universidad Simón Bolívar, Apartado 89.000, Valle de Sartenejas, Caracas 1081-A, Venezuela.
| | - José Bubis
- Departamento de Biología Celular, Universidad Simón Bolívar, Apartado 89.000, Valle de Sartenejas, Caracas 1081-A, Venezuela.
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24
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Domingos ACB, Iacida EC, de Oliveira RM, Bonini-Domingos CR, de Mattos CDCB, de Mattos LC. Type-2 diabetes mellitus and the frequency of the G22A polymorphism of the adenosine deaminase gene in a mixed population in Brazil. Trans R Soc Trop Med Hyg 2014; 108:439-43. [PMID: 24836059 DOI: 10.1093/trstmh/tru076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Most individuals diagnosed with diabetes mellitus (about 90%) have type 2 disease (T2DM). T2DM is associated with a high genetic predisposition and is characterized by changes in the secretion and action of insulin. There have been reports of increased activity of the adenosine deaminase enzyme in individuals with coronary heart disease and DM. METHODS We evaluated 162 patients with T2DM and 160 individuals without the disease. Additionally, a subgroup of 81 individuals at higher risk of developing cardiovascular diseases was formed from the group of patients with diabetes on the basis of their serum levels of high-density lipoprotein cholesterol (HDLc), low-density lipoprotein cholesterol (LDLc) and triglycerides. PCR-RFLP was performed to analyze the TaqI polymorphism G428A of the ADA gene; this technique identifies the ADA*01 and ADA*02 alleles. RESULTS Genotype frequencies were calculated for three patient groups, as follows. Patients with diabetes: ADA*01;*01 (142/159, 89.3%), ADA*01;*02 (16/159, 10.1%) and ADA*02;*02 (1/159, 0.6%); control group: ADA*01;*01 (146/160, 91.3%), ADA*01;*02 (12/160, 7.5%) and ADA*02;*02 (2/160, 1.3%); patients at risk of cardiovascular disease: ADA*01;*01 (71/78, 91.0%), ADA*01;*02 (7/78, 9.0%) and ADA*02;*02 (0/78, 0.0%). CONCLUSION No statistically significant differences between the groups were observed in the genotype and allele frequencies. However, this fact does not rule out the need for further studies on the frequencies of this polymorphism in the Brazilian population, on any association with ADA enzyme activity, and on other risk factors that can affect the quality of life of Brazilian patients with T2DM.
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Duvall LB, Taghert PH. E and M circadian pacemaker neurons use different PDF receptor signalosome components in drosophila. J Biol Rhythms 2013; 28:239-48. [PMID: 23929551 DOI: 10.1177/0748730413497179] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We used real-time imaging to detect cAMP levels in neurons of intact fly brains to study the mechanisms of circadian pacemaker synchronization by the neuropeptide pigment dispersing factor (PDF) in Drosophila. PDF receptor (PDF-R) is expressed by both M (sLNv) and E (LNd) pacemaker subclasses and is coupled to G(sα) in both cases. We previously reported that PDF-R in M pacemakers elevates cAMP levels by activating the ortholog of mammalian adenylate cyclase 3 (AC3) but that AC3 disruptions had no effect on E pacemaker sensitivity to PDF. Here, we show that PDF-R in E pacemakers activates a different AC isoform, AC78C, an ortholog of mammalian AC8. Knockdown of AC78C by transgenic RNAi substantially reduces, but does not completely abrogate, PDF responses in these E pacemakers. The knockdown effect is intact when restricted to mature stages, suggesting a physiological and not a development role for AC78C in E pacemakers. The AC78C phenotype is rescued by the overexpression of AC78C but not by overexpression of the rutabaga AC. AC78C overexpression does not disrupt PDF responses in these E pacemakers, and neither AC78C knockdown nor its overexpression disrupted locomotor rhythms. Finally, knockdown of 2 AKAPs, nervy and AKAP200, partially reduces LNd PDF responses. These findings begin to identify the components of E pacemaker PDF-R signalosomes and indicate that they are distinct from PDF-R signalosomes in M pacemakers: we propose they contain AC78C and at least 1 other AC.
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Affiliation(s)
- Laura B Duvall
- Department of Anatomy & Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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27
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MANN THADDEUS, JONES ROY, SHERINS RICHARDJ, DUFAU MARIAL. Observations on Cyclic Nucleotides in Human Semen. ACTA ACUST UNITED AC 2013. [DOI: 10.1002/j.1939-4640.1981.tb00624.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Haga T. Molecular properties of muscarinic acetylcholine receptors. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2013; 89:226-256. [PMID: 23759942 PMCID: PMC3749793 DOI: 10.2183/pjab.89.226] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2013] [Accepted: 04/30/2013] [Indexed: 05/28/2023]
Abstract
Muscarinic acetylcholine receptors, which comprise five subtypes (M1-M5 receptors), are expressed in both the CNS and PNS (particularly the target organs of parasympathetic neurons). M1-M5 receptors are integral membrane proteins with seven transmembrane segments, bind with acetylcholine (ACh) in the extracellular phase, and thereafter interact with and activate GTP-binding regulatory proteins (G proteins) in the intracellular phase: M1, M3, and M5 receptors interact with Gq-type G proteins, and M2 and M4 receptors with Gi/Go-type G proteins. Activated G proteins initiate a number of intracellular signal transduction systems. Agonist-bound muscarinic receptors are phosphorylated by G protein-coupled receptor kinases, which initiate their desensitization through uncoupling from G proteins, receptor internalization, and receptor breakdown (down regulation). Recently the crystal structures of M2 and M3 receptors were determined and are expected to contribute to the development of drugs targeted to muscarinic receptors. This paper summarizes the molecular properties of muscarinic receptors with reference to the historical background and bias to studies performed in our laboratories.
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Affiliation(s)
- Mitchell A Lazar
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, and The Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA.
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Denis C, Saulière A, Galandrin S, Sénard JM, Galés C. Probing heterotrimeric G protein activation: applications to biased ligands. Curr Pharm Des 2012; 18:128-44. [PMID: 22229559 DOI: 10.2174/138161212799040466] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2011] [Accepted: 11/09/2011] [Indexed: 12/17/2022]
Abstract
Cell surface G protein-coupled receptors (GPCRs) drive numerous signaling pathways involved in the regulation of a broad range of physiologic processes. Today, they represent the largest target for modern drugs development with potential application in all clinical fields. Recently, the concept of "ligand-directed trafficking" has led to a conceptual revolution in pharmacological theory, thus opening new avenues for drug discovery. Accordingly, GPCRs do not function as simple on-off switch but rather as filters capable of selecting the activation of specific signals and thus generating texture responses to ligands, a phenomenon often referred to as ligand-biased signaling. Also, one challenging task today remains optimization of pharmacological assays with increased sensitivity so to better appreciate the inherent texture of ligands. However, considering that a single receptor has pleiotropic signaling properties and that each signal can crosstalk at different levels, biased activity remains thus difficult to evaluate. One strategy to overcome these limitations would be examining the initial steps following receptor activation. Even, if some G protein independent functions have been recently described, heterotrimeric G protein activation remains a general hallmark for all GPCRs families and the first cellular event subsequent to agonist binding to the receptor. Herein, we review the different methodologies classically used or recently developed to monitor G protein activation and discussed them in the context of G protein biased-ligands.
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Affiliation(s)
- Colette Denis
- Institut des Maladies Métaboliques et Cardiovasculaires, Université Toulouse III Paul Sabatier, Centre Hospitalier Universitaire de Toulouse, France.
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Somvanshi RK, Kumar U. Pathophysiology of GPCR Homo- and Heterodimerization: Special Emphasis on Somatostatin Receptors. Pharmaceuticals (Basel) 2012; 5:417-46. [PMID: 24281555 PMCID: PMC3763651 DOI: 10.3390/ph5050417] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 04/18/2012] [Accepted: 04/19/2012] [Indexed: 12/19/2022] Open
Abstract
G-protein coupled receptors (GPCRs) are cell surface proteins responsible for translating >80% of extracellular reception to intracellular signals. The extracellular information in the form of neurotransmitters, peptides, ions, odorants etc is converted to intracellular signals via a wide variety of effector molecules activating distinct downstream signaling pathways. All GPCRs share common structural features including an extracellular N-terminal, seven-transmembrane domains (TMs) linked by extracellular/intracellular loops and the C-terminal tail. Recent studies have shown that most GPCRs function as dimers (homo- and/or heterodimers) or even higher order of oligomers. Protein-protein interaction among GPCRs and other receptor proteins play a critical role in the modulation of receptor pharmacology and functions. Although ~50% of the current drugs available in the market target GPCRs, still many GPCRs remain unexplored as potential therapeutic targets, opening immense possibility to discover the role of GPCRs in pathophysiological conditions. This review explores the existing information and future possibilities of GPCRs as tools in clinical pharmacology and is specifically focused for the role of somatostatin receptors (SSTRs) in pathophysiology of diseases and as the potential candidate for drug discovery.
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Affiliation(s)
- Rishi K Somvanshi
- Faculty of Pharmaceutical Sciences, Division of Pharmacology and Toxicology, The University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
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Lafontan M. Historical perspectives in fat cell biology: the fat cell as a model for the investigation of hormonal and metabolic pathways. Am J Physiol Cell Physiol 2011; 302:C327-59. [PMID: 21900692 DOI: 10.1152/ajpcell.00168.2011] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
For many years, there was little interest in the biochemistry or physiology of adipose tissue. It is now well recognized that adipocytes play an important dynamic role in metabolic regulation. They are able to sense metabolic states via their ability to perceive a large number of nervous and hormonal signals. They are also able to produce hormones, called adipokines, that affect nutrient intake, metabolism and energy expenditure. The report by Rodbell in 1964 that intact fat cells can be obtained by collagenase digestion of adipose tissue revolutionized studies on the hormonal regulation and metabolism of the fat cell. In the context of the advent of systems biology in the field of cell biology, the present seems an appropriate time to look back at the global contribution of the fat cell to cell biology knowledge. This review focuses on the very early approaches that used the fat cell as a tool to discover and understand various cellular mechanisms. Attention essentially focuses on the early investigations revealing the major contribution of mature fat cells and also fat cells originating from adipose cell lines to the discovery of major events related to hormone action (hormone receptors and transduction pathways involved in hormonal signaling) and mechanisms involved in metabolite processing (hexose uptake and uptake, storage, and efflux of fatty acids). Dormant preadipocytes exist in the stroma-vascular fraction of the adipose tissue of rodents and humans; cell culture systems have proven to be valuable models for the study of the processes involved in the formation of new fat cells. Finally, more recent insights into adipocyte secretion, a completely new role with major metabolic impact, are also briefly summarized.
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Affiliation(s)
- Max Lafontan
- Institut National de la Santé et de la Recherche Médicale, UMR, Hôpital Rangueil, Toulouse, France.
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Palczewski K. Oligomeric forms of G protein-coupled receptors (GPCRs). Trends Biochem Sci 2010; 35:595-600. [PMID: 20538466 DOI: 10.1016/j.tibs.2010.05.002] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 04/27/2010] [Accepted: 05/04/2010] [Indexed: 12/21/2022]
Abstract
Oligomerization is a general characteristic of cell membrane receptors that is shared by G protein-coupled receptors (GPCRs) together with their G protein partners. Recent studies of these complexes, both in vivo and in purified reconstituted forms, unequivocally support this contention for GPCRs, perhaps with only rare exceptions. As evidence has evolved from experimental cell lines to more relevant in vivo studies and from indirect biophysical approaches to well defined isolated complexes of dimeric receptors alone and complexed with G proteins, there is an expectation that the structural basis of oligomerization and the functional consequences for membrane signaling will be elucidated. Oligomerization of cell membrane receptors is fully supported by both thermodynamic calculations and the selectivity and duration of signaling required to reach targets located in various cellular compartments.
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Affiliation(s)
- Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4965, USA.
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Abstract
O exercício aeróbio promove efeitos benéficos na prevenção e tratamento de doenças como hipertensão arterial, aterosclerose, insuficiência venosa e doença arterial periférica. Os receptores β-adrenérgicos estão presentes em várias células. No sistema cardiovascular, promovem inotropismo e cronotropismo positivo cardíaco e relaxamento vascular. Embora os efeitos do exercício tenham sido investigados em receptores cardíacos, estudos focados nos vasos são escassos e controversos. Esta revisão abordará os efeitos do exercício físico sobre os receptores β-adrenérgicos vasculares em modelos animais e humanos e os mecanismos celulares envolvidos na resposta relaxante. Em geral, os estudos mostram resultantes conflitantes, onde observam diminuição, aumento ou nenhum efeito do exercício físico sobre a resposta relaxante. Assim, os efeitos do exercício na sensibilidade β-adrenérgica vascular merecem maior atenção, e os resultados mostram que a área de fisiopatologia vascular é um campo aberto para a descoberta de novos compostos e avanços na prática clínica.
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Tcherkezian J, Brittis PA, Thomas F, Roux PP, Flanagan JG. Transmembrane receptor DCC associates with protein synthesis machinery and regulates translation. Cell 2010; 141:632-44. [PMID: 20434207 DOI: 10.1016/j.cell.2010.04.008] [Citation(s) in RCA: 189] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 12/21/2009] [Accepted: 03/22/2010] [Indexed: 11/17/2022]
Abstract
Extracellular signals regulate protein translation in many cell functions. A key advantage of control at the translational level is the opportunity to regulate protein synthesis within specific cellular subregions. However, little is known about mechanisms that may link extracellular cues to translation with spatial precision. Here, we show that a transmembrane receptor, DCC, forms a binding complex containing multiple translation components, including eukaryotic initiation factors, ribosomal large and small subunits, and monosomes. In neuronal axons and dendrites DCC colocalizes in particles with translation machinery, and newly synthesized protein. The extracellular ligand netrin promoted DCC-mediated translation and disassociation of translation components. The functional and physical association of a cell surface receptor with the translation machinery leads to a generalizable model for localization and extracellular regulation of protein synthesis, based on a transmembrane translation regulation complex.
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Affiliation(s)
- Joseph Tcherkezian
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
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Wikberg JE. Adrenergic receptors: classification, ligand binding and molecular properties. ACTA MEDICA SCANDINAVICA. SUPPLEMENTUM 2009; 665:19-36. [PMID: 6297264 DOI: 10.1111/j.0954-6820.1982.tb00405.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The interaction of catecholamines and drugs with adrenergic receptors leads to a set of biochemical reactions which ultimately results in a physiological response. A brief review is given of the classification of adrenergic receptors into subtypes and the use of ligand binding techniques for the identification and characterization of these receptors. Recent advances in the biochemistry of adrenergic receptors are reviewed with special reference to the interaction of the beta and alpha 2-receptors with guanine nucleotide regulatory proteins and adenylate cyclase. The role of calcium and phosphoinositides in the function of the alpha 1-receptor is also discussed.
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MESH Headings
- Animals
- Cell Membrane/metabolism
- Humans
- Ligands
- Models, Biological
- Models, Chemical
- Radioligand Assay
- Receptors, Adrenergic/metabolism
- Receptors, Adrenergic, alpha/classification
- Receptors, Adrenergic, alpha/drug effects
- Receptors, Adrenergic, alpha/metabolism
- Receptors, Adrenergic, beta/classification
- Receptors, Adrenergic, beta/drug effects
- Receptors, Adrenergic, beta/metabolism
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Na⁺,K⁺-ATPase as the Target Enzyme for Organic and Inorganic Compounds. SENSORS 2008; 8:8321-8360. [PMID: 27873990 PMCID: PMC3791021 DOI: 10.3390/s8128321] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 11/09/2008] [Accepted: 12/11/2008] [Indexed: 01/16/2023]
Abstract
This paper gives an overview of the literature data concerning specific and non specific inhibitors of Na+,K+-ATPase receptor. The immobilization approaches developed to improve the rather low time and temperature stability of Na+,K+-ATPase, as well to preserve the enzyme properties were overviewed. The functional immobilization of Na+,K+-ATPase receptor as the target, with preservation of the full functional protein activity and access of various substances to an optimum number of binding sites under controlled conditions in the combination with high sensitive technology for the detection of enzyme activity is the basis for application of this enzyme in medical, pharmaceutical and environmental research.
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Okamoto H, Kimura M, Watanabe N, Ogihara M. Tumor necrosis factor (TNF) receptor-2-mediated DNA synthesis and proliferation in primary cultures of adult rat hepatocytes: The involvement of endogenous transforming growth factor-alpha. Eur J Pharmacol 2008; 604:12-9. [PMID: 19100731 DOI: 10.1016/j.ejphar.2008.12.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 11/18/2008] [Accepted: 12/01/2008] [Indexed: 12/22/2022]
Abstract
We investigated the effects of tumor necrosis factor (TNF)-alpha on DNA synthesis and proliferation, and its signal transduction pathways in primary cultures of adult rat hepatocytes. TNF-alpha induced time- and dose-dependent increases in hepatocyte DNA synthesis and proliferation. The hepatocyte proliferation stimulated by 30 ng/ml TNF-alpha was significantly inhibited by anti-TNF receptor 2 antibody, but not by anti-TNF receptor 1 antibody. TNF-alpha-induced hepatocyte DNA synthesis and proliferation were blocked by AG1478 (10(-7) M), PD98059 (10(-6) M), LY 294002 (10(-7) M), and rapamycin (100 ng/ml). TNF-alpha at 30 ng/ml significantly increased phosphorylation of receptor tyrosine kinase (175 kDa) and p42 mitogen-activated protein (MAP) kinase. This data suggests that the proliferative signal for primary cultured hepatocytes induced by TNF-alpha is mediated by TNF receptor 2 and the receptor tyrosine kinase/MAP kinase pathway. In addition, TNF-alpha-induced hepatocyte mitogenesis was significantly blocked by somatostatin (10(-6) M), adenylate cyclase inhibitor dideoxyadenosine (10(-7) M), protein kinase A inhibitor H-89 (10(-7) M), and neutralizing antibody to transforming growth factor (TGF)-alpha in culture. Indeed, 30 ng/ml TNF-alpha was found to rapidly stimulate secretion of TGF-alpha, and this secretion was also blocked by anti-TNF receptor 2 antibody. Moreover, TGF-alpha secretion induced by TNF-alpha was suppressed by dideoxyadenosine, H-89, and somatostatin. Together, these results indicate that stimulation of TNF receptor 2 by 30 ng/ml TNF-alpha induces autocrine secretion of TGF-alpha via the adenylate cyclase/protein kinase A pathway, after which TGF-alpha induces hepatocyte DNA synthesis and proliferation through the TGF-alpha receptor-linked tyrosine kinase (175 kDa)/MAP kinase signaling system.
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Affiliation(s)
- Hiroshi Okamoto
- Department of Clinical Pharmacology, Faculty of Pharmaceutical Sciences, Josai University. 1-1 Keyakidai, Sakado City, Saitama 350-0295, Japan
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Sýkora J, Bourová L, Hof M, Svoboda P. The effect of detergents on trimeric G-protein activity in isolated plasma membranes from rat brain cortex: correlation with studies of DPH and Laurdan fluorescence. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1788:324-32. [PMID: 19071083 DOI: 10.1016/j.bbamem.2008.11.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2008] [Revised: 11/11/2008] [Accepted: 11/11/2008] [Indexed: 10/21/2022]
Abstract
The effect of non-ionic detergents on baclofen (GABAB-R agonist)-stimulated G-protein activity was measured as a [(35)S]GTPgammaS binding assay in the plasma membranes (PM) isolated from the brain tissue. The effect was clearly biphasic--a decrease in the activity was followed by an activation maximum and finally, at high concentrations, drastic inhibition of the G-protein activity was noticed. Contrarily, specific radioligand binding to GABAB-receptor was inhibited in the whole range of detergent concentrations step by step, i.e. it was strictly monophasic. The magnitude of both detergent effects was decreased in the same order of potency: Brij58>Triton X-100>Digitonin. The identical order was found when comparing detergents ability to alter fluorescence anisotropy of the membrane probe 1,6-diphenyl-1,3,5-hexatriene (rDPH) incorporated into the hydrophobic PM interior. Decrease of rDPH, in the order of Brij58>Triton X-100>Digitonin, was reflected as decrease of the S-order parameter and rotation correlation time phi paralleled by an increase of diffusion wobbling constant Dw (analysis by time-resolved fluorescence according to "wobble-in-cone" model). The influence of the detergents on the membrane organization at the polar headgroup region was characterized by Laurdan generalized polarization (GP). As before, the effect of detergents on GP parameters proceeded in the order: Brij58>Triton X-100>Digitonin.
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Affiliation(s)
- J Sýkora
- J. Heyrovsky Institute of Physical Chemistry of the ASCR, v. v. i., Dolejskova 2155/3, 18223 Prague 8, Czech Republic
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Mechanisms of altered β-adrenergic modulation of the cardiovascular system with aging. ACTA ACUST UNITED AC 2008. [DOI: 10.1017/s0959259800002835] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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43
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Abstract
The nanoscale is not just the middle ground between molecular and macroscopic but a dimension that is specifically geared to the gathering, processing, and transmission of chemical-based information. Herein we consider the living cell as an integrated self-regulating complex chemical system run principally by nanoscale miniaturization, and propose that this specific level of dimensional constraint is critical for the emergence and sustainability of cellular life in its minimal form. We address key aspects of the structure and function of the cell interface and internal metabolic processing that are coextensive with the up-scaling of molecular components to globular nanoobjects (integral membrane proteins, enzymes, and receptors, etc) and higher-order architectures such as microtubules, ribosomes, and molecular motors. Future developments in nanoscience could provide the basis for artificial life.
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Affiliation(s)
- Stephen Mann
- Centre for Organized Matter Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK.
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44
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Unson CG. Expression of glucagon receptors in tetracycline-inducible HEK293S GnT1- stable cell lines: an approach toward purification of receptor protein for structural studies. Biopolymers 2008; 90:287-96. [PMID: 18260137 DOI: 10.1002/bip.20951] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Glucagon is a 29-amino acid polypeptide hormone secreted by pancreatic A cells. Together with insulin, it is an important regulator of glucose metabolism. Type 2 diabetes is characterized by reduced insulin secretion from pancreatic B cells and increased glucose output by the liver which has been attributed to abnormally elevated levels of glucagon. The glucagon receptor (GR) is a member of family B G protein-coupled receptors, ligands for which are peptides composed of 30-40 amino acids. The impetus for studying how glucagon interacts with its membrane receptor is to gain insight into the mechanism of glucagon action in normal physiology as well as in diabetes mellitus. The principal approach toward this goal is to design and synthesize antagonists of glucagon that will bind with high affinity to the GR but will not activate it. Site-directed mutagenesis of the GR has provided some insight into the interactions between glucagon and GR. The rational design of potent antagonists has been hampered by the lack of structural information on receptor-bound glucagon. To obtain adequate amounts of receptor protein for structural studies, a tetracycline-inducible HEK293S GnT1(-) cell line that stably expresses human GR at high-levels was developed. The recombinant receptor protein was characterized, solubilized, and isolated by one-step affinity chromatography. This report describes a feasible approach for the preparation of human GR and other family B GPCRs in the quantities required for structural studies.
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46
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Rodbell M. Structure-function relationships in adenylate cyclase systems. CIBA FOUNDATION SYMPOSIUM 2008:3-21. [PMID: 6128188 DOI: 10.1002/9780470720721.ch2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Hormone-sensitive adenylate cyclase systems are composed of hormone-recognition units (R), a nucleotide-regulatory unit (N) for reaction with GTP and divalent cations, and the catalytic unit (C). From the reported sizes of purified R and N subunits and target analysis of functional sizes of these units, the functions of the components for the binding and actions of hormones and GTP require minimally dimers, homologous or heterologous. It is proposed that the catalytic unit exists in the membrane also as a dimer and that its transition to the active state with MgATP as substrate involves corresponding transitions in linked dimers of the hormone-recognition and nucleotide-regulatory units. It is postulated that hormones trigger the activation process by inducing in concert with GTP and divalent cations the appropriate dimer structure of the holoenzyme. In large aggregates of such structures, realignment of only a few occupied holoenzyme units may be sufficient to induce activation of the total aggregate enzyme. This theory serves to explain the synergistic actions of hormones, and how several hormones can activate a common enzyme. It also provides an explanation for 'spare' receptors, and for the efficacy of hormone action.
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47
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Hadley ME, Heward CB, Hruby VJ, Sawyer TK, Yang YC. Biological actions of melanocyte-stimulating hormone. CIBA FOUNDATION SYMPOSIUM 2008; 81:244-62. [PMID: 6268380 DOI: 10.1002/9780470720646.ch14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Melanocyte-stimulating hormone (alpha-melanotropin, MSH) may function in a number of diverse physiological roles. MSH stimulates (1) rapid translocation of melanosomes (melanin granules) in dermal melanophores to effect rapid colour change and (2) melanogenesis in normal and abnormal (melanoma) epidermal melanocytes. Both actions involve (1) initial binding of the peptide on the melanocyte membrane, (2) transduction of signal to adenylate cyclase, and (3) increased cytosolic levels of cyclic AMP. Efforts to prepare radioiodinated MSH and analogues for radioreceptor studies using melanoma membranes and intact cells reveal that conventional iodination procedures inactivate the hormone because of oxidative and iodination effects on specific structural components of the peptide. These effects can be circumvented by the use of synthetically tailored MSH analogues. Transduction of signal from receptor to adenylate cyclase requires calcium, but prostaglandin or beta-adrenoceptor stimulation of melanophores does not. The nucleotide and metal ion requirements for mouse melanoma adenylate cyclase activity have been characterized. There is both a transcriptional and translational requirement for MSH stimulation of tyrosinase activity and melanin production in melanoma cells. Melanosome translocation within melanophores is enhanced in the absence of extracellular calcium. A model for the MSH control of melanosome movements suggests a bifunctional, but compartmentalized, role for calcium in the action of MSH.
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Abstract
The onset of development in most species studied is triggered by one of the largest and longest calcium transients known to us. It is the most studied and best understood aspect of the calcium signals that accompany and control development. Its properties and mechanisms demonstrate what embryos are capable of and thus how the less-understood calcium signals later in development may be generated. The downstream targets of the fertilization calcium signal have also been identified, providing some pointers to the probable targets of calcium signals further on in the process of development. In one species or another, the fertilization calcium signal involves all the known calcium-releasing second messengers and many of the known calcium-signalling mechanisms. These calcium signals also usually take the form of a propagating calcium wave or waves. Fertilization causes the cell cycle to resume, and therefore fertilization signals are cell-cycle signals. In some early embryonic cell cycles, calcium signals also control the progress through each cell cycle, controlling mitosis. Studies of these early embryonic calcium-signalling mechanisms provide a background to the calcium-signalling events discussed in the articles in this issue.
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Affiliation(s)
- Michael Whitaker
- Institute of Cell and Molecular Biology, Newcastle University Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, UK.
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49
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Mize GJ, Harris JE, Takayama TK, Kulman JD. Regulated expression of active biotinylated G-protein coupled receptors in mammalian cells. Protein Expr Purif 2008; 57:280-9. [PMID: 18042400 DOI: 10.1016/j.pep.2007.09.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2007] [Revised: 09/18/2007] [Accepted: 09/19/2007] [Indexed: 11/16/2022]
Affiliation(s)
- Gregory J Mize
- Department of Urology, University of Washington, Seattle, WA 98195, USA
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50
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Rubin RP. A Brief History of Great Discoveries in Pharmacology: In Celebration of the Centennial Anniversary of the Founding of the American Society of Pharmacology and Experimental Therapeutics. Pharmacol Rev 2007; 59:289-359. [DOI: 10.1124/pr.107.70102] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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