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Nichols R, Pittala K, Leander M, Maynard B, Nikolaou P, Marciniak P. The myosuppressin structure-activity relationship for cardiac contractility and its receptor interactions support the presence of a ligand-directed signaling pathway in heart. Peptides 2021; 146:170641. [PMID: 34453985 DOI: 10.1016/j.peptides.2021.170641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 08/11/2021] [Accepted: 08/20/2021] [Indexed: 10/20/2022]
Abstract
The structural conservation and activity of the myosuppressin cardioinhibitory peptide across species suggests it plays an important role in physiology, yet much remains unknown regarding its signaling. We previously reported Drosophila melanogaster myosuppressin (dromyosuppressin, DMS; TDVDHVFLRF-NH2) decreases cardiac contractility through a G protein-coupled receptor, DMS-R2. Our study showed the DMS N-terminus amino acids influence its structure-activity relationship (SAR), yet how they act is not established. We predicted myosuppressin N-terminal amino acids played a role in signaling. Here, we tested our hypothesis in the beetle, Zophobas atratus, using a semi-isolated heart bioassay to explore SAR in a different Order and focus on cardiac signaling. We generated a series of myosuppressin truncated analogs by removing the N-terminal residue and measuring the activity of each structure on cardiac contractility. While DVDHVFLRF-NH2 decreased cardiac contractility, we found VDHVFLRF-NH2, DHVFLRF-NH2, and HVFLRF-NH2 increased activity. In contrast, VFLRF- NH2 decreased activity and FLRF-NH2 was inactive. Next, we analyzed molecular docking data and found the active truncated analogs interacted with the 3-6 lock in DMS-R2, the myosuppressin cardiac receptor, disrupting the salt bridge between H114 and E369, and K289 and Q372. Further, the docking results showed the inhibitory effect on contractility may be associated with contact to Y78, while the analogs that increased contractility lacked this interaction. The data from our study demonstrated N-terminal amino acids played a role in myosuppressin activity and signaling suggesting the cardiac receptor can be targeted by biased agonists. Our myosuppressin cardiac contractility data and predicted receptor interactions describe the presence of functional selectivity in a ligand-directed signaling pathway in heart.
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Affiliation(s)
- R Nichols
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.
| | - K Pittala
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI, 48109, USA; Undergraduate Honors Program, University of Michigan, Ann Arbor, MI, 48109, USA
| | - M Leander
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - B Maynard
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - P Nikolaou
- Department of Animal Physiology and Development, Adam Mickiewicz University, Poznań, Poland
| | - P Marciniak
- Department of Animal Physiology and Development, Adam Mickiewicz University, Poznań, Poland
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Marciniak P, Witek W, Szymczak M, Pacholska-Bogalska J, Chowański S, Kuczer M, Rosiński G. FMRFamide-Related Peptides Signaling Is Involved in the Regulation of Muscle Contractions in Two Tenebrionid Beetles. Front Physiol 2020; 11:456. [PMID: 32477164 PMCID: PMC7235380 DOI: 10.3389/fphys.2020.00456] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 04/14/2020] [Indexed: 12/24/2022] Open
Abstract
Peptidergic signaling regulates various physiological processes in insects. Neuropeptides are important messenger molecules that act as neurotransmitters, neuromodulators or hormones. Neuropeptides with myotropic properties in insects are known as FMRFamide-like peptides (FaLPs). Here, we describe the myotropic effects of the endogenous FaLPs in the regulation of contractile activity of the heart, ejaculatory duct, oviduct and the hindgut in two beetle species, Tenebrio molitor and Zophobas atratus. A putative receptor was identified in silico in both species. Using RT-PCR these putative FaLPs receptors were found in the various tissues of both beetles, including visceral organs. Analysis of the amino acid sequence of the receptor indicated that it is similar to other insect FaLPs receptors and belongs to G-protein coupled receptors. A synthetic FaLP (NSNFLRFa) found as the bioanalogue of both species demonstrated concentration-dependent and organ-specific myoactive properties. The peptide had species–specific cardioactivity, in that it stimulated Z. atratus heart contractions, while slightly inhibiting that of T. molitor and had mainly myostimulatory effect on the examined visceral organs of both beetle species, with the lowest activity in the ejaculatory duct of these beetles. The peptide was the most active in the hindgut of both species, but only at high concentration of 10–5 M. The results suggest that FaLPs are potent modulators of endogenous contractile activity of the visceral muscles in beetles and may indirectly affect various physiological processes.
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Affiliation(s)
- Paweł Marciniak
- Department of Animal Physiology and Development, Adam Mickiewicz University, Poznań, Poland
| | - Wojciech Witek
- Department of Animal Physiology and Development, Adam Mickiewicz University, Poznań, Poland
| | - Monika Szymczak
- Department of Animal Physiology and Development, Adam Mickiewicz University, Poznań, Poland
| | | | - Szymon Chowański
- Department of Animal Physiology and Development, Adam Mickiewicz University, Poznań, Poland
| | - Mariola Kuczer
- Faculty of Chemistry, University of Wrocław, Wrocław, Poland
| | - Grzegorz Rosiński
- Department of Animal Physiology and Development, Adam Mickiewicz University, Poznań, Poland
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3
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Komisarczuk AZ, Kongshaug H, Li M, Nilsen F. RNAi mediated myosuppressin deficiency affects muscle development and survival in the salmon louse (Lepeophtheirus salmonis). Sci Rep 2019; 9:6944. [PMID: 31061463 PMCID: PMC6502818 DOI: 10.1038/s41598-019-43515-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 04/23/2019] [Indexed: 12/05/2022] Open
Abstract
Muscle activity is regulated by stimulatory and inhibitory neuropeptides allowing for contraction and relaxation. In Arthropods, one of the important myoinhibitors is Myosuppressin, belonging to FMRFamide-like peptides, that was shown to have inhibitory effects on visceral muscle contraction and to regulate vital physiological processes including reproduction or feeding. We have identified myosuppressin in salmon louse Lepeophtheirus salmonis (LsalMS) and systematically characterised its function and complex abnormalities emerging after LsalMS knockdown by RNAi in all developmental stages in this species. Immunohistochemistry analysis localized the LsalMS mainly to the central nervous system, but also to the vital organs within the alimentary tract and the reproductive system. The most striking feature of LsalMS deficiency during lice development was severe reduction of the muscle content, with abnormalities detected in both the visceral and skeletal muscles. Moreover, down-regulation of LsalMS affects moulting, spermatophore deposition and feeding by affecting development of the intestinal wall and increasing its contraction frequency.
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Affiliation(s)
- Anna Z Komisarczuk
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgate 53 A/B, 5008, Bergen, Norway.
| | - Heidi Kongshaug
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgate 53 A/B, 5008, Bergen, Norway
| | - Ming Li
- Key Laboratory of Aquaculture Disease Control, Ministry of Agriculture, and State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Frank Nilsen
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgate 53 A/B, 5008, Bergen, Norway
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4
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Ormerod KG, Jung J, Mercier AJ. Modulation of neuromuscular synapses and contraction in Drosophila 3rd instar larvae. J Neurogenet 2018; 32:183-194. [PMID: 30303434 DOI: 10.1080/01677063.2018.1502761] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Over the past four decades, Drosophila melanogaster has become an increasingly important model system for studying the modulation of chemical synapses and muscle contraction by cotransmitters and neurohormones. This review describes how advantages provided by Drosophila have been utilized to investigate synaptic modulation, and it discusses key findings from investigations of cotransmitters and neurohormones that act on body wall muscles of 3rd instar Drosophila larvae. These studies have contributed much to our understanding of how neuromuscular systems are modulated by neuropeptides and biogenic amines, but there are still gaps in relating these peripheral modulatory effects to behavior.
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Affiliation(s)
- Kiel G Ormerod
- a Department of Biology , Massachusetts Institute of Technology , Cambridge , MA , USA
| | - JaeHwan Jung
- b Department of Biological Sciences , Brock University , St. Catharines , Canada
| | - A Joffre Mercier
- b Department of Biological Sciences , Brock University , St. Catharines , Canada
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Leander M, Heimonen J, Brocke T, Rasmussen M, Bass C, Palmer G, Egle J, Mispelon M, Berry K, Nichols R. The 5-amino acid N-terminal extension of non-sulfated drosulfakinin II is a unique target to generate novel agonists. Peptides 2016; 83:49-56. [PMID: 27397853 DOI: 10.1016/j.peptides.2016.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 06/13/2016] [Accepted: 07/07/2016] [Indexed: 10/21/2022]
Abstract
The ability to design agonists that target peptide signaling is a strategy to delineate underlying mechanisms and influence biology. A sequence that uniquely characterizes a peptide provides a distinct site to generate novel agonists. Drosophila melanogaster sulfakinin encodes non-sulfated drosulfakinin I (nsDSK I; FDDYGHMRF-NH2) and nsDSK II (GGDDQFDDYGHMRF-NH2). Drosulfakinin is typical of sulfakinin precursors, which are conserved throughout invertebrates. Non-sulfated DSK II is structurally related to DSK I, however, it contains a unique 5-residue N-terminal extension; drosulfakinins signal through G-protein coupled receptors, DSK-R1 and DSK-R2. Drosulfakinin II distinctly influences adult and larval gut motility and larval locomotion; yet, its structure-activity relationship was unreported. We hypothesized substitution of an N-terminal extension residue may alter nsDSK II activity. By targeting the extension we identified, not unexpectedly, analogs mimicking nsDSK II, yet, surprisingly, we also discovered novel agonists with increased (super) and opposite (protean) effects. We determined [A3] nsDSK II increased larval gut contractility rather than, like nsDSK II, decrease it. [N4] nsDSK II impacted larval locomotion, although nsDSK II was inactive. In adult gut, [A1] nsDSK II, [A2] nsDSKII, and [A3] nsDSK II mimicked nsDSK II, and [A4] nsDSK II and [A5] nsDSK II were more potent; [N3] nsDSK II and [N4] nsDSK II mimicked nsDSK II. This study reports nsDSK II signals through DSK-R2 to influence gut motility and locomotion, identifying a novel role for the N-terminal extension in sulfakinin biology and receptor activation; it also led to the discovery of nsDSK II structural analogs that act as super and protean agonists.
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Affiliation(s)
- M Leander
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - J Heimonen
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - T Brocke
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - M Rasmussen
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - C Bass
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - G Palmer
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - J Egle
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - M Mispelon
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - K Berry
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - R Nichols
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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Cho EH, Lim JC, Lee SY, Jung SH. An assessment tumor targeting ability of (177)Lu labeled cyclic CCK analogue peptide by binding with cholecystokinin receptor. J Pharmacol Sci 2016; 131:209-14. [PMID: 27430985 DOI: 10.1016/j.jphs.2016.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 06/21/2016] [Accepted: 06/22/2016] [Indexed: 01/14/2023] Open
Abstract
The cholecystokinin (CCK) receptor is known as a receptor that is overexpressed in many human tumors. The present study was designed to investigate the targeting ability of cyclic CCK analogue in AR42J pancreatic cells. The CCK analogues, DOTA-K(glucose)-Gly-Trp-Nle-Asp-Phe (DOTA-glucose-CCK) and DOTA-Nle-cyclo(Glu-Trp-Nle-Asp-Phe-Lys-NH2) (DOTA-[Nle]-cCCK), were synthesized and radiolabeled with (177)Lu, and competitive binding was evaluated. The binding appearance of synthesized peptide with AR42J cells was evaluated by confocal microscopy. And bio-distribution was performed in AR42J xenografted mice. Synthesized peptides were prepared by a solid phase synthesis method, and their purity was over 98%. DOTA is the chelating agent for (177)Lu-labeling, in which the peptides were radiolabeled with (177)Lu by a high radiolabeling yield. A competitive displacement of (125)I-CCK8 on the AR42J cells revealed that the 50% inhibitory concentration value (IC50) was 12.3 nM of DOTA-glucose-CCK and 1.7 nM of DOTA-[Nle]-cCCK. Radio-labeled peptides were accumulated in AR42J tumor in vivo, and %ID/g of the tumor was 0.4 and 0.9 at 2 h p.i. It was concluded that (177)Lu-DOTA-[Nle]-cCCK has higher binding affinity than (177)Lu-DOTA-glucose-CCK and can be a potential candidate as a targeting modality for a CCK receptor over-expressing tumors.
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Affiliation(s)
- Eun-Ha Cho
- RI Research Division, Research Reactor Utilization Department, Korea Atomic Energy Research Institute (KAERI), Daejeon 305-353, Republic of Korea.
| | - Jae Cheong Lim
- RI Research Division, Research Reactor Utilization Department, Korea Atomic Energy Research Institute (KAERI), Daejeon 305-353, Republic of Korea
| | - So-Young Lee
- RI Research Division, Research Reactor Utilization Department, Korea Atomic Energy Research Institute (KAERI), Daejeon 305-353, Republic of Korea
| | - Sung-Hee Jung
- RI Research Division, Research Reactor Utilization Department, Korea Atomic Energy Research Institute (KAERI), Daejeon 305-353, Republic of Korea
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7
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The neurotransmitters serotonin and glutamate accelerate the heart rate of the mosquito Anopheles gambiae. Comp Biochem Physiol A Mol Integr Physiol 2015; 188:49-57. [DOI: 10.1016/j.cbpa.2015.06.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 06/12/2015] [Accepted: 06/15/2015] [Indexed: 11/22/2022]
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8
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Rasmussen M, Leander M, Ons S, Nichols R. Conserved molecular switch interactions in modeled cardioactive RF-NH2 peptide receptors: Ligand binding and activation. Peptides 2015. [PMID: 26211890 DOI: 10.1016/j.peptides.2015.07.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Peptides may act through G protein-coupled receptors to influence cardiovascular performance; thus, delineating mechanisms involved in signaling is a molecular-based strategy to influence health. Molecular switches, often represented by conserved motifs, maintain a receptor in an inactive state. However, once the switch is broken, the transmembrane regions move and activation occurs. The molecular switches of Drosophila melanogaster myosuppressin (MS) receptors were previously identified to include a unique ionic lock and novel 3-6 lock, as well as transmission and tyrosine toggle switches. In addition to MS, cardioactive ligands structurally related by a C-terminal RF-NH2 include sulfakinin, neuropeptide F (NPF), short NPF, and FMRF-NH2-containing peptide subfamilies. We hypothesized receptor molecular switch motifs were conserved within a RF-NH2 subfamily and across species. Thus, we investigated RF-NH2 receptor (RFa-R) molecular switches in D. melanogaster, Tribolium castaneum, Anopheles gambiae, Rhodnius prolixus, and Bombyx mori. Adipokinetic hormone (AKH), which does not contain a RF-NH2, was also examined. The tyrosine toggle switch and ionic lock showed a higher degree of conservation within a RF-NH2 subfamily than the transmission switch and 3-7 lock. AKH receptor motifs were not representative of a RF-NH2 subfamily. The motifs and interactions of switches in the RFa-Rs were consistent with receptor activation and ligand-specific binding.
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Affiliation(s)
- M Rasmussen
- Chemistry Undergraduate Program, University of Michigan, Ann Arbor, MI 48109-1055, USA; Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI 48109-0600, USA
| | - M Leander
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI 48109-0600, USA
| | - S Ons
- Laboratorio de Genética y Genómica Funcional, Centro Regional de Estudios Genómicos, Facultad de ciencias Exactas, Universidad Nacional de La Plata, Bv. 120 1459, Buenos Aires, Argentina
| | - R Nichols
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI 48109-0600, USA.
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Leander M, Bass C, Marchetti K, Maynard BF, Wulff JP, Ons S, Nichols R. Cardiac contractility structure-activity relationship and ligand-receptor interactions; the discovery of unique and novel molecular switches in myosuppressin signaling. PLoS One 2015; 10:e0120492. [PMID: 25793503 PMCID: PMC4368603 DOI: 10.1371/journal.pone.0120492] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 01/22/2015] [Indexed: 11/19/2022] Open
Abstract
Peptidergic signaling regulates cardiac contractility; thus, identifying molecular switches, ligand-receptor contacts, and antagonists aids in exploring the underlying mechanisms to influence health. Myosuppressin (MS), a decapeptide, diminishes cardiac contractility and gut motility. Myosuppressin binds to G protein-coupled receptor (GPCR) proteins. Two Drosophila melanogaster myosuppressin receptors (DrmMS-Rs) exist; however, no mechanism underlying MS-R activation is reported. We predicted DrmMS-Rs contained molecular switches that resembled those of Rhodopsin. Additionally, we believed DrmMS-DrmMS-R1 and DrmMS-DrmMS-R2 interactions would reflect our structure-activity relationship (SAR) data. We hypothesized agonist- and antagonist-receptor contacts would differ from one another depending on activity. Lastly, we expected our study to apply to other species; we tested this hypothesis in Rhodnius prolixus, the Chagas disease vector. Searching DrmMS-Rs for molecular switches led to the discovery of a unique ionic lock and a novel 3-6 lock, as well as transmission and tyrosine toggle switches. The DrmMS-DrmMS-R1 and DrmMS-DrmMS-R2 contacts suggested tissue-specific signaling existed, which was in line with our SAR data. We identified R. prolixus (Rhp)MS-R and discovered it, too, contained the unique myosuppressin ionic lock and novel 3-6 lock found in DrmMS-Rs as well as transmission and tyrosine toggle switches. Further, these motifs were present in red flour beetle, common water flea, honey bee, domestic silkworm, and termite MS-Rs. RhpMS and DrmMS decreased R. prolixus cardiac contractility dose dependently with EC50 values of 140 nM and 50 nM. Based on ligand-receptor contacts, we designed RhpMS analogs believed to be an active core and antagonist; testing on heart confirmed these predictions. The active core docking mimicked RhpMS, however, the antagonist did not. Together, these data were consistent with the unique ionic lock, novel 3-6 lock, transmission switch, and tyrosine toggle switch being involved in mechanisms underlying TM movement and MS-R activation, and the ability of MS agonists and antagonists to influence physiology.
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Affiliation(s)
- Megan Leander
- Undergraduate Biochemistry Program, Chemistry Department, University of Michigan, Ann Arbor, Michigan, United States of America, 48109
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, Michigan, United States of America, 48109
| | - Chloe Bass
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, Michigan, United States of America, 48109
- Undergraduate Chemistry Program, Chemistry Department, University of Michigan, Ann Arbor, Michigan, United States of America, 48109
| | - Kathryn Marchetti
- Undergraduate Biochemistry Program, Chemistry Department, University of Michigan, Ann Arbor, Michigan, United States of America, 48109
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, Michigan, United States of America, 48109
| | - Benjamin F. Maynard
- Undergraduate Biochemistry Program, Chemistry Department, University of Michigan, Ann Arbor, Michigan, United States of America, 48109
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, Michigan, United States of America, 48109
| | - Juan Pedro Wulff
- Laboratorio de Genética y Genómica Funcional, Centro Regional de Estudios Genómicos, Facultad de ciencias Exactas, Universidad Nacional de La Plata, Bv. 120 1459, Buenos Aires, Argentina
| | - Sheila Ons
- Laboratorio de Genética y Genómica Funcional, Centro Regional de Estudios Genómicos, Facultad de ciencias Exactas, Universidad Nacional de La Plata, Bv. 120 1459, Buenos Aires, Argentina
| | - Ruthann Nichols
- Undergraduate Biochemistry Program, Chemistry Department, University of Michigan, Ann Arbor, Michigan, United States of America, 48109
- Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, Michigan, United States of America, 48109
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10
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Dickinson PS, Calkins A, Stevens JS. Related neuropeptides use different balances of unitary mechanisms to modulate the cardiac neuromuscular system in the American lobster, Homarus americanus. J Neurophysiol 2014; 113:856-70. [PMID: 25392168 DOI: 10.1152/jn.00585.2014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
To produce flexible outputs, neural networks controlling rhythmic motor behaviors can be modulated at multiple levels, including the pattern generator itself, sensory feedback, and the response of the muscle to a given pattern of motor output. We examined the role of two related neuropeptides, GYSDRNYLRFamide (GYS) and SGRNFLRFamide (SGRN), in modulating the neurogenic lobster heartbeat, which is controlled by the cardiac ganglion (CG). When perfused though an isolated whole heart at low concentrations, both peptides elicited increases in contraction amplitude and frequency. At higher concentrations, both peptides continued to elicit increases in contraction amplitude, but GYS caused a decrease in contraction frequency, while SGRN did not alter frequency. To determine the sites at which these peptides induce their effects, we examined the effects of the peptides on the periphery and on the isolated CG. When we removed the CG and stimulated the motor nerve with constant bursts of stimuli, both GYS and SGRN increased contraction amplitude, indicating that each peptide modulates the muscle or the neuromuscular junction. When applied to the isolated CG, neither peptide altered burst frequency at low peptide concentrations; at higher concentrations, SGRN decreased burst frequency, whereas GYS continued to have no effect on frequency. Together, these data suggest that the two peptides elicit some of their effects using different mechanisms; in particular, given the known feedback pathways within this system, the importance of the negative (nitric oxide) relative to the positive (stretch) feedback pathways may differ in the presence of the two peptides.
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Affiliation(s)
- Patsy S Dickinson
- Department of Biology and Neuroscience Program, Bowdoin College, Brunswick, Maine
| | - Andrew Calkins
- Department of Biology and Neuroscience Program, Bowdoin College, Brunswick, Maine
| | - Jake S Stevens
- Department of Biology and Neuroscience Program, Bowdoin College, Brunswick, Maine
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11
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Hillyer JF, Estévez-Lao TY, de la Parte LE. Myotropic effects of FMRFamide containing peptides on the heart of the mosquito Anopheles gambiae. Gen Comp Endocrinol 2014; 202:15-25. [PMID: 24747482 DOI: 10.1016/j.ygcen.2014.03.048] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 03/19/2014] [Accepted: 03/27/2014] [Indexed: 11/24/2022]
Abstract
FMRFamide-like peptides (FLPs) are produced by invertebrate and vertebrate animals, and regulate diverse physiological processes. In insects, several FLPs modulate heart physiology, with some increasing and others decreasing dorsal vessel contraction dynamics. Here, we describe the FMRFamide gene structure in the mosquito, Anopheles gambiae, quantify the developmental and spatial expression of FMRFamide and its putative receptor (FMRFamideR), and show that the peptides FMRFamide and SALDKNFMRFamide have complex myotropic properties. RACE sequencing showed that the FMRFamide gene encodes eight putative FLPs and is alternatively spliced. Of the eight FLPs, only one is shared by A. gambiae, Aedes aegypti and Culex quinquefasciatus: SALDKNFMRFamide. Quantitative PCR showed that peak expression of FMRFamide and FMRFamideR occurs in second instar larvae and around eclosion. In adults, FMRFamide is primarily transcribed in the head and thorax, and FMRFamideR is primarily transcribed in the thorax. Intravital video imaging of mosquitoes injected FMRFamide and SALDKNFMRFamide revealed that at low doses these peptides increase heart contraction rates. At high doses, however, these peptides decrease heart contraction rates and alter the proportional directionality of heart contractions. Taken altogether, these data describe the FMRFamide gene in A. gambiae, and show that FLPs are complex modulators of mosquito circulatory physiology.
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Affiliation(s)
- Julián F Hillyer
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.
| | - Tania Y Estévez-Lao
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
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12
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Yu N, Swevers L, Nachman RJ, Smagghe G. Development of cell-based bioassay with Sf9 cells expressing TcSKR1 and TcSKR2 and differential activation by sulfated and non-sulfated SK peptides. Peptides 2014; 53:238-42. [PMID: 24582608 DOI: 10.1016/j.peptides.2014.01.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 01/17/2014] [Accepted: 01/17/2014] [Indexed: 11/19/2022]
Abstract
Insect sulfakinin receptors (SKRs) are G-protein-coupled receptors (GPCRs) that interact with sulfakinins (SKs) to modulate diverse biological processes. One of the indispensable roles of SKs is in the regulation of food intake in insects. In this project we report on the development of a cell-based receptor assay system with insect Sf9 cells, expressing TcSKR1 and TcSKR2 from the red flour beetle Tribolium castaneum, a model and important pest insect in agriculture. In this system, a stable presence of the two TcSKRs was supported by Western blotting. The expressed TcSKRs were coupled to Gαs-protein upon activation and stimulated cAMP accumulation in Sf9 cells. Exposure of the transfected cell lines to sulfated SK (sSK) activated TcSKR1 at 1 nM; the EC50 of sSK to obtain 50% of receptor activation was similar for both receptors. In contrast, μM concentrations of non-sulfated SK were necessary to activate both TcSKRs. In conclusion, this cell-based TcSKR assay system is useful to screen SK-related peptides and mimetics and to better document ligand-receptor structure-activity relationships. Given the importance of SK signaling system in insects, the present study may provide new insights on the development of new methods to control pest insects.
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Affiliation(s)
- Na Yu
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, 9000 Gent, Belgium
| | - Luc Swevers
- Insect Molecular Genetics and Biotechnology, Institute of Biosciences and Applications National Centre for Scientific Research "Demokritos", Athens, Greece
| | - Ronald J Nachman
- Insect Control and Cotton Disease Research, Southern Plains Agricultural Research Center, USDA, College Station, TX 77845, USA
| | - Guy Smagghe
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, 9000 Gent, Belgium.
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