1
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Bhatia V, Maghsoudi S, Hinton M, Bhagirath AY, Singh N, Jaggupilli A, Chelikani P, Dakshinamurti S. Characterization of Adenylyl Cyclase Isoform 6 Residues Interacting with Forskolin. BIOLOGY 2023; 12:biology12040572. [PMID: 37106773 PMCID: PMC10135528 DOI: 10.3390/biology12040572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 03/26/2023] [Accepted: 04/03/2023] [Indexed: 04/29/2023]
Abstract
BACKGROUND The adenylyl cyclase (AC) pathway, crucial for pulmonary vasodilation, is inhibited by hypoxia. Forskolin (FSK) binds allosterically to AC, stimulating ATP catalysis. As AC6 is the primary AC isoform in the pulmonary artery, selective reactivation of AC6 could provide targeted reinstatement of hypoxic AC activity. This requires elucidation of the FSK binding site in AC6. METHODS HEK293T cells stably overexpressing AC 5, 6, or 7 were incubated in normoxia (21% O2) or hypoxia (10% O2) or exposed to s-nitrosocysteine (CSNO). AC activity was measured using terbium norfloxacin assay; AC6 structure built by homology modeling; ligand docking to examine FSK-interacting amino acids; roles of selected residues determined by site-directed mutagenesis; FSK-dependent cAMP generation measured in wild-type and FSK-site mutants by biosensor-based live cell assay. RESULTS Only AC6 is inhibited by hypoxia and nitrosylation. Homology modeling and docking revealed residues T500, N503, and S1035 interacting with FSK. Mutation of T500, N503, or S1035 decreased FSK-stimulated AC activity. FSK site mutants were not further inhibited by hypoxia or CSNO; however, mutation of any of these residues prevented AC6 activation by FSK following hypoxia or CSNO treatment. CONCLUSIONS FSK-interacting amino acids are not involved in the hypoxic inhibition mechanism. This study provides direction to design FSK derivatives for selective activation of hypoxic AC6.
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Affiliation(s)
- Vikram Bhatia
- Biology of Breathing Theme, Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
- Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada
- Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, MB R3A 1S1, Canada
| | - Saeid Maghsoudi
- Biology of Breathing Theme, Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
| | - Martha Hinton
- Biology of Breathing Theme, Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
| | - Anjali Y Bhagirath
- Biology of Breathing Theme, Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
- Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada
| | - Nisha Singh
- Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada
| | | | - Prashen Chelikani
- Biology of Breathing Theme, Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
- Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
| | - Shyamala Dakshinamurti
- Biology of Breathing Theme, Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
- Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, MB R3A 1S1, Canada
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
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2
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Bhatia V, de Jesus VC, Shaik FA, Jaggupilli A, Singh N, Chelikani P, Atukorallaya D. Extraoral expression and characterization of bitter taste receptors in
Astyanax mexicanus
(Mexican Tetra Fish). FASEB Bioadv 2022; 4:574-584. [PMID: 36089978 PMCID: PMC9447421 DOI: 10.1096/fba.2022-00032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 04/29/2022] [Accepted: 05/04/2022] [Indexed: 11/11/2022] Open
Affiliation(s)
- Vikram Bhatia
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology University of Manitoba Dr. Gerald Niznick College of Dentistry, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E0W2 Canada
- Children’s Hospital Research Institute of Manitoba (CHRIM), Winnipeg MB R3E3P4 Canada
| | - Vivianne Cruz de Jesus
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology University of Manitoba Dr. Gerald Niznick College of Dentistry, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E0W2 Canada
- Children’s Hospital Research Institute of Manitoba (CHRIM), Winnipeg MB R3E3P4 Canada
| | - Feroz Ahmed Shaik
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology University of Manitoba Dr. Gerald Niznick College of Dentistry, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E0W2 Canada
| | - Appalaraju Jaggupilli
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology University of Manitoba Dr. Gerald Niznick College of Dentistry, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E0W2 Canada
| | - Nisha Singh
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology University of Manitoba Dr. Gerald Niznick College of Dentistry, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E0W2 Canada
| | - Prashen Chelikani
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology University of Manitoba Dr. Gerald Niznick College of Dentistry, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E0W2 Canada
- Children’s Hospital Research Institute of Manitoba (CHRIM), Winnipeg MB R3E3P4 Canada
| | - Devi Atukorallaya
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology University of Manitoba Dr. Gerald Niznick College of Dentistry, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E0W2 Canada
- Children’s Hospital Research Institute of Manitoba (CHRIM), Winnipeg MB R3E3P4 Canada
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3
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Bhagirath AY, Bhatia V, Medapati MR, Singh N, Hinton M, Chelikani P, Dakshinamurti S. Critical cysteines in the functional interaction of adenylyl cyclase isoform 6 with Gαs. FASEB Bioadv 2021; 4:180-196. [PMID: 35664968 PMCID: PMC9159366 DOI: 10.1096/fba.2021-00073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 10/11/2021] [Accepted: 11/08/2021] [Indexed: 11/17/2022] Open
Abstract
Activation of adenylyl cyclases (ACs) by G‐protein Gαs catalyzes the production of cyclic adenosine monophosphate (cAMP), a key second messenger that regulates diverse physiological responses. There are 10 AC isoforms present in humans, with AC5 and AC6 proposed to play vital roles in cardiac function. We have previously shown that under hypoxic conditions, AC6 is amenable to post‐translational modification by nitrosylation, resulting in decreased AC catalytic activity. Using a computational model of the AC6–Gαs complex, we predicted key nitrosylation‐amenable cysteine residues involved in the interaction of AC6 with Gαs and pursued a structure–function analysis of these cysteine residues in both AC6 and Gαs. Our results based on site‐directed mutagenesis of AC6 and Gαs, a constitutively active Gαs, AC activity, and live cell intracellular cAMP assays suggest that Cys1004 in AC6 (subunit C2) and Cys237 in Gαs are present at the AC–Gαs interface and are important for the activation of AC6 by Gαs. We further provide mechanistic evidence to show that mutating Cys 1004 in the second catalytic domain of AC6 makes it amenable to inhibition by Gαi, which may account for decreased functional activity of AC6 when this residue is unavailable.
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Affiliation(s)
- Anjali Y. Bhagirath
- Biology of Breathing Theme Children's Hospital Research Institute of Manitoba (CHRIM) Winnipeg Manitoba Canada
- Department of Oral Biology University of Manitoba Winnipeg Manitoba Canada
| | - Vikram Bhatia
- Biology of Breathing Theme Children's Hospital Research Institute of Manitoba (CHRIM) Winnipeg Manitoba Canada
- Department of Oral Biology University of Manitoba Winnipeg Manitoba Canada
| | | | - Nisha Singh
- Department of Oral Biology University of Manitoba Winnipeg Manitoba Canada
| | - Martha Hinton
- Biology of Breathing Theme Children's Hospital Research Institute of Manitoba (CHRIM) Winnipeg Manitoba Canada
- Department of Physiology and Pathophysiology University of Manitoba Winnipeg Manitoba Canada
| | - Prashen Chelikani
- Biology of Breathing Theme Children's Hospital Research Institute of Manitoba (CHRIM) Winnipeg Manitoba Canada
- Department of Oral Biology University of Manitoba Winnipeg Manitoba Canada
| | - Shyamala Dakshinamurti
- Biology of Breathing Theme Children's Hospital Research Institute of Manitoba (CHRIM) Winnipeg Manitoba Canada
- Department of Physiology and Pathophysiology University of Manitoba Winnipeg Manitoba Canada
- Department of Pediatrics University of Manitoba Winnipeg Manitoba Canada
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4
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Abarghooi Kahaki F, Monzavi S, Bamehr H, Bandani E, Payandeh Z, Jahangiri A, Khalili S. Expression and Purification of Membrane Proteins in Different Hosts. Int J Pept Res Ther 2020. [DOI: 10.1007/s10989-019-10009-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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5
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Wiseman DN, Otchere A, Patel JH, Uddin R, Pollock NL, Routledge SJ, Rothnie AJ, Slack C, Poyner DR, Bill RM, Goddard AD. Expression and purification of recombinant G protein-coupled receptors: A review. Protein Expr Purif 2020; 167:105524. [PMID: 31678667 PMCID: PMC6983937 DOI: 10.1016/j.pep.2019.105524] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 10/28/2019] [Accepted: 10/29/2019] [Indexed: 01/15/2023]
Abstract
Given their extensive role in cell signalling, GPCRs are significant drug targets; despite this, many of these receptors have limited or no available prophylaxis. Novel drug design and discovery significantly rely on structure determination, of which GPCRs are typically elusive. Progress has been made thus far to produce sufficient quantity and quality of protein for downstream analysis. As such, this review highlights the systems available for recombinant GPCR expression, with consideration of their advantages and disadvantages, as well as examples of receptors successfully expressed in these systems. Additionally, an overview is given on the use of detergents and the styrene maleic acid (SMA) co-polymer for membrane solubilisation, as well as purification techniques.
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Affiliation(s)
- Daniel N Wiseman
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, UK.
| | - Abigail Otchere
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, UK.
| | - Jaimin H Patel
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, UK.
| | - Romez Uddin
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, UK.
| | | | - Sarah J Routledge
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, UK.
| | - Alice J Rothnie
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, UK.
| | - Cathy Slack
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, UK.
| | - David R Poyner
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, UK.
| | - Roslyn M Bill
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, UK.
| | - Alan D Goddard
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, UK.
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6
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Shaik FA, Chelikani P. Differential effects of membrane sphingomyelin and cholesterol on agonist-induced bitter taste receptor T2R14 signaling. Mol Cell Biochem 2019; 463:57-66. [DOI: 10.1007/s11010-019-03628-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Accepted: 09/12/2019] [Indexed: 01/15/2023]
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7
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Shaik FA, Jaggupilli A, Chelikani P. Highly conserved intracellular H208 residue influences agonist selectivity in bitter taste receptor T2R14. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:183057. [PMID: 31493373 DOI: 10.1016/j.bbamem.2019.183057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 08/23/2019] [Accepted: 08/26/2019] [Indexed: 11/19/2022]
Abstract
Bitter taste receptors (T2Rs) are a specialized class of cell membrane receptors of the G protein-coupled receptor family and perform a crucial role in chemosensation. The 25 T2Rs in humans are activated by structurally diverse ligands of plant, animal and microbial origin. The mechanisms of activation of these receptors are poorly understood. Therefore, identification of structural determinants of T2Rs that regulate its efficacy could be beneficial in understanding the molecular mechanisms of T2R activation. In this work, we characterized a highly conserved histidine (H208), present at TM5-ICL3 region of T2R14 and its role in agonist-induced T2R14 signaling. Surprisingly, mutation of the conserved H208 (H208A) did not result in increased basal activity of T2R14, in contrast to similar H206A mutation in T2R4 that showed constitutive or basal activity. However, H208A mutation in T2R14 resulted in an increase in agonist-induced efficacy for Flufenamic acid (FFA). Interestingly, H208A did not affect the potency of another T2R14 agonist Diphenhydramine (DPH). The H208R compensatory mutation showed FFA response similar to wild-type T2R14. Molecular modeling suggests a FFA-induced shift in TM3 and TM5 helices of H208A, which changes the network of interactions connecting TM5-ICL3-TM6. This report identifies a crucial residue on the intracellular surface of T2Rs that is involved in bitter ligand selectivity. It also highlights the varied roles carried out by some conserved residues in different T2Rs.
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Affiliation(s)
- Feroz Ahmed Shaik
- Manitoba Chemosensory Biology Research Group, Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba, Winnipeg, MB, Canada
| | - Appalaraju Jaggupilli
- Manitoba Chemosensory Biology Research Group, Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba, Winnipeg, MB, Canada
| | - Prashen Chelikani
- Manitoba Chemosensory Biology Research Group, Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba, Winnipeg, MB, Canada.
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8
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Jaggupilli A, Howard R, Aluko RE, Chelikani P. Advanced Glycation End-Products Can Activate or Block Bitter Taste Receptors. Nutrients 2019; 11:nu11061317. [PMID: 31212814 PMCID: PMC6628017 DOI: 10.3390/nu11061317] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 06/07/2019] [Accepted: 06/10/2019] [Indexed: 12/14/2022] Open
Abstract
Bitter taste receptors (T2Rs) are expressed in several tissues of the body and are involved in a variety of roles apart from bitter taste perception. Advanced glycation end-products (AGEs) are produced by glycation of amino acids in proteins. There are varying sources of AGEs, including dietary food products, as well as endogenous reactions within our body. Whether these AGEs are T2R ligands remains to be characterized. In this study, we selected two AGEs, namely, glyoxal-derived lysine dimer (GOLD) and carboxymethyllysine (CML), based on their predicted interaction with the well-studied T2R4, and its physiochemical properties. Results showed predicted binding affinities (Kd) for GOLD and CML towards T2R4 in the nM and μM range, respectively. Calcium mobilization assays showed that GOLD inhibited quinine activation of T2R4 with IC50 10.52 ± 4.7 μM, whilst CML was less effective with IC50 32.62 ± 9.5 μM. To characterize whether this antagonism was specific to quinine activated T2R4 or applicable to other T2Rs, we selected T2R14 and T2R20, which are expressed at significant levels in different human tissues. A similar effect of GOLD was observed with T2R14; and in contrast, GOLD and CML activated T2R20 with an EC50 of 79.35 ± 29.16 μM and 65.31 ± 17.79 μM, respectively. In this study, we identified AGEs as novel T2R ligands that caused either activation or inhibition of different T2Rs.
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Affiliation(s)
- Appalaraju Jaggupilli
- Manitoba Chemosensory Biology Research Group, Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba (CHRIM), Winnipeg, MB R3E 0W4, Canada.
| | - Ryan Howard
- Manitoba Chemosensory Biology Research Group, Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba (CHRIM), Winnipeg, MB R3E 0W4, Canada.
| | - Rotimi E Aluko
- Department of Food and Human Nutritional Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
| | - Prashen Chelikani
- Manitoba Chemosensory Biology Research Group, Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba (CHRIM), Winnipeg, MB R3E 0W4, Canada.
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9
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Shaik FA, Medapati MR, Chelikani P. Cholesterol modulates the signaling of chemosensory bitter taste receptor T2R14 in human airway cells. Am J Physiol Lung Cell Mol Physiol 2019; 316:L45-L57. [PMID: 30358435 DOI: 10.1152/ajplung.00169.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Bitter taste receptors (T2Rs) are a group of 25 chemosensory receptors expressed at significant levels in the human airways. In human airways, bitter taste receptor 14 (T2R14)-mediated physiological response in ameliorating obstructive airway disorders is an active area of investigation. Therefore, understanding various factors regulating the structure and function of T2R14 will be beneficial. We hypothesize that membrane lipids like cholesterol play a regulatory role in T2R14 signaling in airway cells. We confirmed the expression and signaling of T2R14 in primary human airway smooth muscle (HASM) cells and the human airway epithelial cell line (NuLi-1) using immunoblot analysis and intracellular calcium concentration mobilization experiments, respectively. Next, T2R14 signaling was examined in membrane cholesterol-altered environments by methyl-β-cyclodextrin or cholesterol oxidase treatments. In the cells analyzed, cholesterol depletion affected the agonist-induced T2R14 signaling, and cholesterol replenishment rescued its efficacy. An alternative approach for cholesterol depletion (with cholesterol oxidase pretreatment) also negatively affected the agonist potency at T2R14 in HASM cells. To understand the molecular mechanism of interaction between cholesterol and T2R14, we used site-directed mutagenesis coupled with functional assays and examined the role of putative cholesterol-binding motifs (CRAC and CARC) in T2R14. Functional characterization of wild-type and mutant T2R14 receptors suggests that amino acid residues K110, F236, and L239 are crucial in T2R14-cholesterol functional interaction. In conclusion, our results show that cholesterol influences the T2R14 signaling efficacy by forming direct interactions with the receptor and consequently plays a regulatory role in T2R14-mediated signaling in human airway cells.
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Affiliation(s)
- Feroz Ahmed Shaik
- Manitoba Chemosensory Biology Research Group, University of Manitoba, Manitoba, Canada.,Department of Oral Biology, University of Manitoba, Manitoba, Canada.,Children's Hospital Research Institute of Manitoba , Winnipeg, Manitoba , Canada
| | - Manoj Reddy Medapati
- Manitoba Chemosensory Biology Research Group, University of Manitoba, Manitoba, Canada.,Department of Oral Biology, University of Manitoba, Manitoba, Canada.,Children's Hospital Research Institute of Manitoba , Winnipeg, Manitoba , Canada
| | - Prashen Chelikani
- Manitoba Chemosensory Biology Research Group, University of Manitoba, Manitoba, Canada.,Department of Oral Biology, University of Manitoba, Manitoba, Canada.,Children's Hospital Research Institute of Manitoba , Winnipeg, Manitoba , Canada
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10
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Haas MJ, Jurado-Flores M, Hammoud R, Plazarte G, Onstead-Haas L, Wong NC, Mooradian AD. Regulation of apolipoprotein A-I gene expression by the histamine H1 receptor: Requirement for NF-κB. Life Sci 2018; 208:102-110. [DOI: 10.1016/j.lfs.2018.07.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 06/27/2018] [Accepted: 07/12/2018] [Indexed: 01/22/2023]
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11
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Jaggupilli A, Singh N, De Jesus VC, Gounni MS, Dhanaraj P, Chelikani P. Chemosensory bitter taste receptors (T2Rs) are activated by multiple antibiotics. FASEB J 2018; 33:501-517. [PMID: 30011231 DOI: 10.1096/fj.201800521rr] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Many medications including antibiotics taste bitter. The potency of these antibiotics on the 25 bitter taste receptors (T2Rs) in humans remains poorly understood. Here we characterize by sensory and structure-function analyses how antibiotics frequently used to treat airway infections in cystic fibrosis activate multiple human T2Rs. The potency of the broad-spectrum antibiotics, tobramycin, levofloxacin, and azithromycin on the highly expressed T2Rs in airways, T2R4, T2R14, and T2R20 was pursued. The amino acids and structural features of T2R4, T2R14, and T2R20 important for antibiotic binding were characterized by mutational analysis in heterologous cell-based assays. Strikingly, extracellular loop 2 in T2Rs performs a key function in binding to antibiotics with contribution from residues in transmembrane helices. Our results suggest that different antibiotics activate multiple T2Rs with different potencies. An understanding of the nonantibiotic and physiologic effects mediated through T2Rs on the host cells is much needed.-Jaggupilli, A., Singh, N., De Jesus, V. C., Gounni, M. S., Dhanaraj, P., Chelikani, P. Chemosensory bitter taste receptors (T2Rs) are activated by multiple antibiotics.
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Affiliation(s)
- Appalaraju Jaggupilli
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba (CHRIM), Winnipeg, Manitoba, Canada
| | - Nisha Singh
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba (CHRIM), Winnipeg, Manitoba, Canada
| | - Vivianne Cruz De Jesus
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba (CHRIM), Winnipeg, Manitoba, Canada
| | - Mohamed Soussi Gounni
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba (CHRIM), Winnipeg, Manitoba, Canada
| | - Premnath Dhanaraj
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba (CHRIM), Winnipeg, Manitoba, Canada
| | - Prashen Chelikani
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba (CHRIM), Winnipeg, Manitoba, Canada
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12
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Jaggupilli A, Singh N, Jesus VCD, Duan K, Chelikani P. Characterization of the Binding Sites for Bacterial Acyl Homoserine Lactones (AHLs) on Human Bitter Taste Receptors (T2Rs). ACS Infect Dis 2018; 4:1146-1156. [PMID: 29799189 DOI: 10.1021/acsinfecdis.8b00094] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The 25 bitter taste receptors (T2Rs) in humans are novel players in mediating host-pathogen responses in the airways and innate immunity. The chemosensory T2Rs are expressed in different extraoral tissues and perform diverse pathophysiological roles from mediating bronchodilation to detecting bacterial infection in the airways. T2Rs were suggested to be activated by multiple bacterial quorum sensing molecules (QSMs). However, whether bacterial QSMs bind to T2Rs and the structural features on T2Rs has not yet been characterized. Here, we analyzed the taste sensory profiles of QSMs including acyl homoserine lactones (C4-AHL, C8-AHL, and 3-oxo-C12-AHL) and hydroxyquinolones (HHQ and NHQ) predominantly secreted by Gram-negative bacteria and characterized the candidate T2Rs interacting with different QSMs using structure-function approaches. The potency of the above QSMs for T2Rs significantly expressed in the airways, namely T2R4, T2R14, and T2R20, was characterized. 3-Oxo-C12-AHL activated T2R4, T2R14, and T2R20, while C8-AHL activated T2R4 and T2R14 with strong potency. The T2R amino acid residues involved in the interactions were characterized by molecular-model-guided site-directed mutagenesis. AHLs bind to a similar orthosteric site present on the extracellular surface in all three T2Rs with significant contributions from residues in extracellular loop 2. Our results reveal the mode of binding of AHLs for different T2Rs and provide biochemical insights into their interactions. This study will facilitate mechanistic studies aimed at understanding the role of these T2Rs as "sensors" of bacteria and in host-pathogen interactions.
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Affiliation(s)
- Appalaraju Jaggupilli
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology, University of Manitoba, Children’s Hospital Research Institute of Manitoba (CHRIM), Winnipeg, MB R3E 0W4, Canada
| | - Nisha Singh
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology, University of Manitoba, Children’s Hospital Research Institute of Manitoba (CHRIM), Winnipeg, MB R3E 0W4, Canada
| | - Vivianne Cruz De Jesus
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology, University of Manitoba, Children’s Hospital Research Institute of Manitoba (CHRIM), Winnipeg, MB R3E 0W4, Canada
| | - Kangmin Duan
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology, University of Manitoba, Children’s Hospital Research Institute of Manitoba (CHRIM), Winnipeg, MB R3E 0W4, Canada
| | - Prashen Chelikani
- Manitoba Chemosensory Biology Research Group and Department of Oral Biology, University of Manitoba, Children’s Hospital Research Institute of Manitoba (CHRIM), Winnipeg, MB R3E 0W4, Canada
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13
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Chakraborty R, Sikarwar AS, Hinton M, Dakshinamurti S, Chelikani P. Characterization of GPCR signaling in hypoxia. Methods Cell Biol 2018; 142:101-110. [PMID: 28964329 DOI: 10.1016/bs.mcb.2017.07.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
G protein-coupled receptors (GPCRs) signal in response to various external stimuli including stress. GPCR signaling has been shown to play a critical role in the adaptation of cell response to limited oxygen supply. Hypoxia has been implicated in cardiovascular diseases, human pulmonary arterial responses, and persistent pulmonary hypertension in newborns. One of the key GPCRs implicated in hypoxia is the prostanoid receptor, thromboxane A2 receptor (TP). Hypoxia can affect TP localization, stability, and activity both in vivo and in vitro. To elucidate hypoxia-mediated GPCR signaling in vitro, we lay out a general strategy to perform hypoxic experiments using both primary pulmonary artery smooth muscle cells and TP expressed in HEK293T cells. We describe assay for measuring moderate tissue hypoxia using static cell cultures, monitoring pericellular media oxygen content, and signaling of TP.
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Affiliation(s)
- Raja Chakraborty
- College of Dentistry, Winnipeg, MB, Canada; Manitoba Chemosensory Biology (MCSB) Research Group, University of Manitoba, Winnipeg, MB, Canada; Biology of Breathing Group, Children's Hospital Research Institute of Manitoba, Winnipeg, MB, Canada
| | - Anurag Singh Sikarwar
- College of Dentistry, Winnipeg, MB, Canada; Manitoba Chemosensory Biology (MCSB) Research Group, University of Manitoba, Winnipeg, MB, Canada; Biology of Breathing Group, Children's Hospital Research Institute of Manitoba, Winnipeg, MB, Canada
| | - Martha Hinton
- Biology of Breathing Group, Children's Hospital Research Institute of Manitoba, Winnipeg, MB, Canada; College of Medicine, University of Manitoba, Winnipeg, MB, Canada
| | - Shyamala Dakshinamurti
- Manitoba Chemosensory Biology (MCSB) Research Group, University of Manitoba, Winnipeg, MB, Canada; Biology of Breathing Group, Children's Hospital Research Institute of Manitoba, Winnipeg, MB, Canada; College of Medicine, University of Manitoba, Winnipeg, MB, Canada
| | - Prashen Chelikani
- College of Dentistry, Winnipeg, MB, Canada; Manitoba Chemosensory Biology (MCSB) Research Group, University of Manitoba, Winnipeg, MB, Canada; Biology of Breathing Group, Children's Hospital Research Institute of Manitoba, Winnipeg, MB, Canada.
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14
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Liu K, Jaggupilli A, Premnath D, Chelikani P. Plasticity of the ligand binding pocket in the bitter taste receptor T2R7. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:991-999. [PMID: 29355483 DOI: 10.1016/j.bbamem.2018.01.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 01/03/2018] [Accepted: 01/11/2018] [Indexed: 01/12/2023]
Abstract
Bitter taste receptors (T2Rs) are a group of 25 G protein-coupled receptors (GPCRs) in humans. The cognate agonists and the mechanism of ligand binding to the majority of the T2Rs remain unknown. Here we report the first structure-function analysis of T2R7 and study the ability of this receptor to bind to different agonists by site-directed mutagenesis. Screening of ligands for T2R7 in calcium based assays lead to the identification of novel compounds that activate this receptor. Quinine, diphenidol, dextromethorphan and diphenhydramine showed substantial activation of T2R7. Interestingly, these bitter compounds showed different pharmacological characteristics. To investigate the structural features in T2R7 that might contribute to the observed differences in agonist specificities, molecular model guided ligand docking and site-directed mutagenesis was pursued. Amino acids D65, D86, W89, N167, T169, W170, S181, T255 and E271 in the ligand-binding pocket were replaced and the mutants characterized pharmacologically. Our results suggest D86, S181 and W170 present on the extracellular side of transmembrane 3 (TM3), TM5 and in extracellular loop 2 (ECL2) are essential for agonist binding in T2R7. Mutations of these amino acids lead to loss-of-function. We also identified gain-of-function residues that are agonist specific. These results suggest that agonists bind at an extracellular site rather than deep within the TM core involving residues present in both ECL2 and TM helices in T2R7. Similar to majority of the Class A GPCRs, ECL2 in T2R7 plays a significant role in agonist binding and activation.
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Affiliation(s)
- Kun Liu
- From the Manitoba Chemosensory Biology Research Group and Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba (CHRIM), Winnipeg, MB R3E 0W4. Canada
| | - Appalaraju Jaggupilli
- From the Manitoba Chemosensory Biology Research Group and Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba (CHRIM), Winnipeg, MB R3E 0W4. Canada
| | - Dhanaraj Premnath
- From the Manitoba Chemosensory Biology Research Group and Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba (CHRIM), Winnipeg, MB R3E 0W4. Canada
| | - Prashen Chelikani
- From the Manitoba Chemosensory Biology Research Group and Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba (CHRIM), Winnipeg, MB R3E 0W4. Canada.
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15
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Medapati MR, Singh A, Korupally RR, Henderson D, Klonisch T, Manda SV, Chelikani P. Characterization of GPCRs in extracellular vesicle (EV). Methods Cell Biol 2017; 142:119-132. [PMID: 28964331 DOI: 10.1016/bs.mcb.2017.07.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Extracellular vesicle (EV) are tiny membranous vesicles usually <500nm in size that recently emerged as a new paradigm in human intercellular signaling. EVs have shown a promising role in development of diagnostic markers in many pathophysiological disorders. The presence of chemosensory and therapeutically relevant G protein-coupled receptors (GPCRs) on EV membranes is poorly characterized. Here, we compare different methods including ultracentrifugation and polymer-charge-based separation to isolate EVs from cell culture media and human saliva. The presence of bitter taste GPCRs (T2R4 and T2R38) and a class A GPCR angiotensin II type 1 receptor on these EVs was characterized by qPCR, ELISA, and immunotransmission electron microscopy.
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MESH Headings
- Cell Line
- Enzyme-Linked Immunosorbent Assay
- Extracellular Vesicles/metabolism
- Humans
- Microscopy, Electron, Transmission/methods
- Microscopy, Immunoelectron/methods
- Oligopeptides/chemistry
- Real-Time Polymerase Chain Reaction
- Receptor, Angiotensin, Type 1/chemistry
- Receptor, Angiotensin, Type 1/isolation & purification
- Receptor, Angiotensin, Type 1/ultrastructure
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/isolation & purification
- Receptors, G-Protein-Coupled/metabolism
- Receptors, G-Protein-Coupled/ultrastructure
- Ultracentrifugation/methods
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Affiliation(s)
- Manoj R Medapati
- College of Dentistry, Rady Faculty of Health of Sciences, Winnipeg, MB, Canada; Manitoba Chemosensory Biology (MCSB) Research Group, University of Manitoba, Winnipeg, MB, Canada
| | - Anula Singh
- Apollo Hospitals Educational and Research Foundation, Hyderabad, India
| | | | - Dana Henderson
- Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Thomas Klonisch
- Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Sasidhar V Manda
- Apollo Hospitals Educational and Research Foundation, Hyderabad, India
| | - Prashen Chelikani
- College of Dentistry, Rady Faculty of Health of Sciences, Winnipeg, MB, Canada; Manitoba Chemosensory Biology (MCSB) Research Group, University of Manitoba, Winnipeg, MB, Canada.
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16
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Regulation of Rac1 GTPase activity by quinine through G-protein and bitter taste receptor T2R4. Mol Cell Biochem 2016; 426:129-136. [DOI: 10.1007/s11010-016-2886-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 11/10/2016] [Indexed: 01/02/2023]
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17
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Recombinant protein production from stable mammalian cell lines and pools. Curr Opin Struct Biol 2016; 38:129-36. [DOI: 10.1016/j.sbi.2016.06.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 06/06/2016] [Accepted: 06/06/2016] [Indexed: 11/23/2022]
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