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Richards NJ, Alqallaf A, Mitchell RD, Parnell A, Haidar HB, Almeida JR, Williams J, Vijayakumar P, Balogun A, Matsakas A, Trim SA, Patel K, Vaiyapuri S. Indian Ornamental Tarantula ( Poecilotheria regalis) Venom Affects Myoblast Function and Causes Skeletal Muscle Damage. Cells 2023; 12:2074. [PMID: 37626884 PMCID: PMC10453882 DOI: 10.3390/cells12162074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 08/03/2023] [Accepted: 08/09/2023] [Indexed: 08/27/2023] Open
Abstract
Envenomation by the Indian ornamental tarantula (Poecilotheria regalis) is medically relevant to humans, both in its native India and worldwide, where they are kept as pets. Muscle-related symptoms such as cramps and pain are commonly reported in humans following envenomation by this species. There is no specific treatment, including antivenom, for its envenomation. Moreover, the scientific knowledge of the impact of this venom on skeletal muscle function is highly limited. Therefore, we carried out this study to better understand the myotoxic properties of Poecilotheria regalis venom by determining its effects in cultured myoblasts and in the tibialis anterior muscle in mice. While there was no effect found on undifferentiated myoblasts, the venom affected differentiated multinucleated myotubes resulting in the reduction of fusion and atrophy of myotubes. Similarly, intramuscular administration of this venom in the tibialis anterior muscle in mice resulted in extensive muscle damage on day 5. However, by day 10, the regeneration was evident, and the regeneration process continued until day 20. Nevertheless, some tissue abnormalities including reduced dystrophin expression and microthrombi presence were observed on day 20. Overall, this study demonstrates the ability of this venom to induce significant muscle damage and affect its regeneration in the early stages. These data provide novel mechanistic insights into this venom-induced muscle damage and guide future studies to isolate and characterise individual toxic component(s) that induce muscle damage and their significance in developing better therapeutics.
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Affiliation(s)
- Nicholas J. Richards
- School of Biological Sciences, University of Reading, Reading RG6 6UB, UK; (N.J.R.); (A.A.); (A.P.); (H.B.H.)
| | - Ali Alqallaf
- School of Biological Sciences, University of Reading, Reading RG6 6UB, UK; (N.J.R.); (A.A.); (A.P.); (H.B.H.)
- Medical Services Authority, Ministry of Defence, Kuwait City 13012, Kuwait
| | | | - Andrew Parnell
- School of Biological Sciences, University of Reading, Reading RG6 6UB, UK; (N.J.R.); (A.A.); (A.P.); (H.B.H.)
- Micregen Ltd., Thames Valley Science Park, Reading RG2 9LH, UK;
| | - Husain Bin Haidar
- School of Biological Sciences, University of Reading, Reading RG6 6UB, UK; (N.J.R.); (A.A.); (A.P.); (H.B.H.)
| | - José R. Almeida
- School of Pharmacy, University of Reading, Reading RG6 6UB, UK; (J.R.A.); (J.W.); (P.V.)
| | - Jarred Williams
- School of Pharmacy, University of Reading, Reading RG6 6UB, UK; (J.R.A.); (J.W.); (P.V.)
| | - Pradeep Vijayakumar
- School of Pharmacy, University of Reading, Reading RG6 6UB, UK; (J.R.A.); (J.W.); (P.V.)
| | - Adedoyin Balogun
- Molecular Physiology Laboratory, Centre for Biomedicine, Hull York Medical School, Hull HU6 7RX, UK
| | - Antonios Matsakas
- Molecular Physiology Laboratory, Centre for Biomedicine, Hull York Medical School, Hull HU6 7RX, UK
| | | | - Ketan Patel
- School of Biological Sciences, University of Reading, Reading RG6 6UB, UK; (N.J.R.); (A.A.); (A.P.); (H.B.H.)
| | - Sakthivel Vaiyapuri
- School of Pharmacy, University of Reading, Reading RG6 6UB, UK; (J.R.A.); (J.W.); (P.V.)
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2
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Kalapothakis Y, Miranda K, Molina DAM, Conceição IMCA, Larangote D, Op den Camp HJM, Kalapothakis E, Chávez-Olórtegui C, Borges A. An overview of Tityus cisandinus scorpion venom: Transcriptome and mass fingerprinting reveal conserved toxin homologs across the Amazon region and novel lipolytic components. Int J Biol Macromol 2023; 225:1246-1266. [PMID: 36427608 DOI: 10.1016/j.ijbiomac.2022.11.185] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 11/09/2022] [Accepted: 11/18/2022] [Indexed: 11/23/2022]
Abstract
Tityus cisandinus, a neglected medically important scorpion in Ecuadorian and Peruvian Amazonia, belongs to a complex of species related to the eastern Amazon endemic Tityus obscurus, spanning a distribution of ca. 4000 km. Despite high morbidity and mortality rates, no effective scorpion antivenom is currently available in the Amazon region. Knowledge of the structural/functional relationships between T. cisandinus venom components and those from related Amazonian species is crucial for designing region-specific therapeutic antivenoms. In this work, we carried out the first venom gland transcriptomic study of an Amazonian scorpion outside Brazil, T. cisandinus. We also fingerprinted its total venom through MALDI-TOF MS, which supported our transcriptomic findings. We identified and calculated the expression level of 94 components: 60 toxins, 25 metalloproteases, five disulfide isomerases, three amidating enzymes, one hyaluronidase, and also uncovered transcripts encoding novel lipolytic beta subunits produced by New World buthid scorpions. This study demonstrates the high similarity between T. cisandinus and T. obscurus venoms, reinforcing the existence of a neglected complex of genetically and toxinologically related Amazonian scorpions of medical importance. Finally, we demonstrated the low recognition of currently available therapeutic sera against T. cisandinus and T. obscurus venoms, and concluded that these should be improved to protect against envenomation by Amazonian Tityus spp.
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Affiliation(s)
- Yan Kalapothakis
- Departamento de Genética, Ecologia e Evolução, ICB, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, CEP: 31270-901 Belo Horizonte, Minas Gerais, Brazil
| | - Kelton Miranda
- Departamento de Genética, Ecologia e Evolução, ICB, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, CEP: 31270-901 Belo Horizonte, Minas Gerais, Brazil
| | - Denis Alexis Molina Molina
- Departamento de Bioquímica e Imunologia, ICB, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, CEP: 31270-901 Belo Horizonte, Minas Gerais, Brazil
| | - Izabela Mamede Costa Andrade Conceição
- Departamento de Bioquímica e Imunologia, ICB, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, CEP: 31270-901 Belo Horizonte, Minas Gerais, Brazil
| | - Débora Larangote
- Departamento de Genética, Ecologia e Evolução, ICB, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, CEP: 31270-901 Belo Horizonte, Minas Gerais, Brazil
| | - Huub J M Op den Camp
- Department of Microbiology, Faculty of Science, Radboud University Nijmegen, Heyendaalseweg 135, NL-6525 AJ Nijmegen, the Netherlands
| | - Evanguedes Kalapothakis
- Departamento de Genética, Ecologia e Evolução, ICB, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, CEP: 31270-901 Belo Horizonte, Minas Gerais, Brazil
| | - Carlos Chávez-Olórtegui
- Departamento de Bioquímica e Imunologia, ICB, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, CEP: 31270-901 Belo Horizonte, Minas Gerais, Brazil
| | - Adolfo Borges
- Instituto de Medicina Experimental, Universidad Central de Venezuela, Caracas, Venezuela; Centro para el Desarrollo de la Investigación Científica, CEDIC, Asunción 1255, Paraguay.
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3
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Pierantozzi E, Szentesi P, Al-Gaadi D, Oláh T, Dienes B, Sztretye M, Rossi D, Sorrentino V, Csernoch L. Calcium Homeostasis Is Modified in Skeletal Muscle Fibers of Small Ankyrin1 Knockout Mice. Int J Mol Sci 2019; 20:ijms20133361. [PMID: 31323924 PMCID: PMC6651408 DOI: 10.3390/ijms20133361] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 07/01/2019] [Accepted: 07/04/2019] [Indexed: 11/16/2022] Open
Abstract
Small Ankyrins (sAnk1) are muscle-specific isoforms generated by the Ank1 gene that participate in the organization of the sarcoplasmic reticulum (SR) of striated muscles. Accordingly, the volume of SR tubules localized around the myofibrils is strongly reduced in skeletal muscle fibers of 4- and 10-month-old sAnk1 knockout (KO) mice, while additional structural alterations only develop with aging. To verify whether the lack of sAnk1 also alters intracellular Ca2+ handling, cytosolic Ca2+ levels were analyzed in stimulated skeletal muscle fibers from 4- and 10-month-old sAnk1 KO mice. The SR Ca2+ content was reduced in sAnk1 KO mice regardless of age. The amplitude of the Ca2+ transients induced by depolarizing pulses was decreased in myofibers of sAnk1 KO with respect to wild type (WT) fibers, while their voltage dependence was not affected. Furthermore, analysis of spontaneous Ca2+ release events (sparks) on saponin-permeabilized muscle fibers indicated that the frequency of sparks was significantly lower in fibers from 4-month-old KO mice compared to WT. Furthermore, both the amplitude and spatial spread of sparks were significantly smaller in muscle fibers from both 4- and 10-month-old KO mice compared to WT. These data suggest that the absence of sAnk1 results in an impairment of SR Ca2+ release, likely as a consequence of a decreased Ca2+ store due to the reduction of the SR volume in sAnk1 KO muscle fibers.
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Affiliation(s)
- Enrico Pierantozzi
- Department of Molecular and Developmental Medicine, Molecular Medicine Section, University of Siena, 53100 Siena, Italy
| | - Péter Szentesi
- Department of Physiology, Medical Faculty, University of Debrecen, H-4002 Debrecen, Hungary
| | - Dána Al-Gaadi
- Department of Physiology, Medical Faculty, University of Debrecen, H-4002 Debrecen, Hungary
- Doctoral School of Molecular Medicine, University of Debrecen, H-4002 Debrecen, Hungary
| | - Tamás Oláh
- Department of Physiology, Medical Faculty, University of Debrecen, H-4002 Debrecen, Hungary
| | - Beatrix Dienes
- Department of Physiology, Medical Faculty, University of Debrecen, H-4002 Debrecen, Hungary
| | - Mónika Sztretye
- Department of Physiology, Medical Faculty, University of Debrecen, H-4002 Debrecen, Hungary
| | - Daniela Rossi
- Department of Molecular and Developmental Medicine, Molecular Medicine Section, University of Siena, 53100 Siena, Italy
| | - Vincenzo Sorrentino
- Department of Molecular and Developmental Medicine, Molecular Medicine Section, University of Siena, 53100 Siena, Italy
| | - László Csernoch
- Department of Physiology, Medical Faculty, University of Debrecen, H-4002 Debrecen, Hungary.
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CPP-Ts: a new intracellular calcium channel modulator and a promising tool for drug delivery in cancer cells. Sci Rep 2018; 8:14739. [PMID: 30282983 PMCID: PMC6170434 DOI: 10.1038/s41598-018-33133-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 09/21/2018] [Indexed: 12/16/2022] Open
Abstract
Scorpion sting envenoming impacts millions of people worldwide, with cardiac effects being one of the main causes of death on victims. Here we describe the first Ca2+ channel toxin present in Tityus serrulatus (Ts) venom, a cell penetrating peptide (CPP) named CPP-Ts. We show that CPP-Ts increases intracellular Ca2+ release through the activation of nuclear InsP3R of cardiomyocytes, thereby causing an increase in the contraction frequency of these cells. Besides proposing a novel subfamily of Ca2+ active toxins, we investigated its potential use as a drug delivery system targeting cancer cell nucleus using CPP-Ts’s nuclear-targeting property. To this end, we prepared a synthetic CPP-Ts sub peptide14–39 lacking pharmacological activity which was directed to the nucleus of specific cancer cell lines. This research identifies a novel subfamily of Ca2+ active toxins and provides new insights into biotechnological applications of animal venoms.
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5
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Xiao L, Gurrola GB, Zhang J, Valdivia CR, SanMartin M, Zamudio FZ, Zhang L, Possani LD, Valdivia HH. Structure-function relationships of peptides forming the calcin family of ryanodine receptor ligands. J Gen Physiol 2017; 147:375-94. [PMID: 27114612 PMCID: PMC4845687 DOI: 10.1085/jgp.201511499] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 03/21/2016] [Indexed: 12/22/2022] Open
Abstract
Calcins are a novel family of scorpion peptides that bind with high affinity to ryanodine receptors (RyRs) and increase their activity by inducing subconductance states. Here, we provide a comprehensive analysis of the structure-function relationships of the eight calcins known to date, based on their primary sequence, three-dimensional modeling, and functional effects on skeletal RyRs (RyR1). Primary sequence alignment and evolutionary analysis show high similarity among all calcins (≥78.8% identity). Other common characteristics include an inhibitor cysteine knot (ICK) motif stabilized by three pairs of disulfide bridges and a dipole moment (DM) formed by positively charged residues clustering on one side of the molecule and neutral and negatively charged residues segregating on the opposite side. [(3)H]Ryanodine binding assays, used as an index of the open probability of RyRs, reveal that all eight calcins activate RyR1 dose-dependently with Kd values spanning approximately three orders of magnitude and in the following rank order: opicalcin1 > opicalcin2 > vejocalcin > hemicalcin > imperacalcin > hadrucalcin > maurocalcin >> urocalcin. All calcins significantly augment the bell-shaped [Ca(2+)]-[(3)H]ryanodine binding curve with variable effects on the affinity constants for Ca(2+) activation and inactivation. In single channel recordings, calcins induce the appearance of a subconductance state in RyR1 that has a unique fractional value (∼20% to ∼60% of the full conductance state) but bears no relationship to binding affinity, DM, or capacity to stimulate Ca(2+) release. Except for urocalcin, all calcins at 100 nM concentration stimulate Ca(2+) release and deplete Ca(2+) load from skeletal sarcoplasmic reticulum. The natural variation within the calcin family of peptides offers a diversified set of high-affinity ligands with the capacity to modulate RyRs with high dynamic range and potency.
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Affiliation(s)
- Liang Xiao
- Department of Marine Biotechnology, Faculty of Naval Medicine, Second Military Medical University, Shanghai 200433, China Center for Arrhythmia Research, Cardiovascular Division, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Georgina B Gurrola
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62271, México Center for Arrhythmia Research, Cardiovascular Division, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Jing Zhang
- Center for Arrhythmia Research, Cardiovascular Division, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Carmen R Valdivia
- Center for Arrhythmia Research, Cardiovascular Division, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Mario SanMartin
- Center for Arrhythmia Research, Cardiovascular Division, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Fernando Z Zamudio
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62271, México Center for Arrhythmia Research, Cardiovascular Division, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Liming Zhang
- Department of Marine Biotechnology, Faculty of Naval Medicine, Second Military Medical University, Shanghai 200433, China
| | - Lourival D Possani
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62271, México
| | - Héctor H Valdivia
- Center for Arrhythmia Research, Cardiovascular Division, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
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6
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Sárközi S, Komáromi I, Jóna I, Almássy J. Lanthanides Report Calcium Sensor in the Vestibule of Ryanodine Receptor. Biophys J 2017; 112:2127-2137. [PMID: 28538150 DOI: 10.1016/j.bpj.2017.03.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 03/11/2017] [Accepted: 03/23/2017] [Indexed: 02/07/2023] Open
Abstract
Ca2+ regulates ryanodine receptor's (RyR) activity through an activating and an inhibiting Ca2+-binding site located on the cytoplasmic side of the RyR channel. Their altered sensitivity plays an important role in the pathology of malignant hyperthermia and heart failure. We used lanthanide ions (Ln3+) as probes to investigate the Ca2+ sensors of RyR, because they specifically bind to Ca2+-binding proteins and they are impermeable to the channel. Eu3+'s and Sm3+'s action was tested on single RyR1 channels reconstituted into planar lipid bilayers. When the activating binding site was saturated by 50 μM Ca2+, Ln3+ potently inhibited RyR's open probability (Kd Eu3+ = 167 ± 5 nM and Kd Sm3+ = 63 ± 3 nM), but in nominally 0 [Ca2+], low [Eu3+] activated the channel. These results suggest that Ln3+ acts as an agonist of both Ca2+-binding sites. More importantly, the voltage-dependent characteristics of Ln3+'s action led to the conclusion that the activating Ca2+ binding site is located within the electrical field of the channel (in the vestibule). This idea was tested by applying the pore blocker toxin maurocalcine on the cytoplasmic side of RyR. These experiments showed that RyR lost reactivity to changing cytosolic [Ca2+] from 50 μM to 100 nM when the toxin occupied the vestibule. These results suggest that maurocalcine mechanically prevented Ca2+ from dissociating from its binding site and support our vestibular Ca2+ sensor-model further.
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Affiliation(s)
- Sándor Sárközi
- Department of Physiology, Faculty of Medicine, Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - István Komáromi
- Division of Clinical Laboratory Science, Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - István Jóna
- Department of Physiology, Faculty of Medicine, Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - János Almássy
- Department of Physiology, Faculty of Medicine, Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
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Kerkis I, de Brandão Prieto da Silva AR, Pompeia C, Tytgat J, de Sá Junior PL. Toxin bioportides: exploring toxin biological activity and multifunctionality. Cell Mol Life Sci 2017; 74:647-661. [PMID: 27554773 PMCID: PMC11107510 DOI: 10.1007/s00018-016-2343-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 07/27/2016] [Accepted: 08/15/2016] [Indexed: 10/21/2022]
Abstract
Toxins have been shown to have many biological functions and to constitute a rich source of drugs and biotechnological tools. We focus on toxins that not only have a specific activity, but also contain residues responsible for transmembrane penetration, which can be considered bioportides-a class of cell-penetrating peptides that are also intrinsically bioactive. Bioportides are potential tools in pharmacology and biotechnology as they help deliver substances and nanoparticles to intracellular targets. Bioportides characterized so far are peptides derived from human proteins, such as cytochrome c (CYCS), calcitonin receptor (camptide), and endothelial nitric oxide synthase (nosangiotide). However, toxins are usually disregarded as potential bioportides. In this review, we discuss the inclusion of some toxins and molecules derived thereof as a new class of bioportides based on structure activity relationship, minimization, and biological activity studies. The comparative analysis of the amino acid residue composition of toxin-derived bioportides and their short molecular variants is an innovative analytical strategy which allows us to understand natural toxin multifunctionality in vivo and plan novel pharmacological and biotechnological products. Furthermore, we discuss how many bioportide toxins have a rigid structure with amphiphilic properties important for both cell penetration and bioactivity.
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Affiliation(s)
- Irina Kerkis
- Laboratório de Genética, Instituto Butantan, Av. Vital Brasil 1500, São Paulo, SP, 05503-900, Brazil.
| | | | - Celine Pompeia
- Laboratório de Genética, Instituto Butantan, Av. Vital Brasil 1500, São Paulo, SP, 05503-900, Brazil
| | - Jan Tytgat
- Toxicology and Pharmacology, University of Leuven (KU Leuven), Louvain, Belgium
| | - Paulo L de Sá Junior
- Laboratório de Genética, Instituto Butantan, Av. Vital Brasil 1500, São Paulo, SP, 05503-900, Brazil.
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8
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Wang X, Gao B, Zhu S. Exon Shuffling and Origin of Scorpion Venom Biodiversity. Toxins (Basel) 2016; 9:toxins9010010. [PMID: 28035955 PMCID: PMC5308243 DOI: 10.3390/toxins9010010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 12/13/2016] [Accepted: 12/21/2016] [Indexed: 12/01/2022] Open
Abstract
Scorpion venom is a complex combinatorial library of peptides and proteins with multiple biological functions. A combination of transcriptomic and proteomic techniques has revealed its enormous molecular diversity, as identified by the presence of a large number of ion channel-targeted neurotoxins with different folds, membrane-active antimicrobial peptides, proteases, and protease inhibitors. Although the biodiversity of scorpion venom has long been known, how it arises remains unsolved. In this work, we analyzed the exon-intron structures of an array of scorpion venom protein-encoding genes and unexpectedly found that nearly all of these genes possess a phase-1 intron (one intron located between the first and second nucleotides of a codon) near the cleavage site of a signal sequence despite their mature peptides remarkably differ. This observation matches a theory of exon shuffling in the origin of new genes and suggests that recruitment of different folds into scorpion venom might be achieved via shuffling between body protein-coding genes and ancestral venom gland-specific genes that presumably contributed tissue-specific regulatory elements and secretory signal sequences.
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Affiliation(s)
- Xueli Wang
- Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects & Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing 100101, China.
| | - Bin Gao
- Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects & Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing 100101, China.
| | - Shunyi Zhu
- Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects & Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing 100101, China.
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In cellulo phosphorylation induces pharmacological reprogramming of maurocalcin, a cell-penetrating venom peptide. Proc Natl Acad Sci U S A 2016; 113:E2460-8. [PMID: 27071086 DOI: 10.1073/pnas.1517342113] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The venom peptide maurocalcin (MCa) is atypical among toxins because of its ability to rapidly translocate into cells and potently activate the intracellular calcium channel type 1 ryanodine receptor (RyR1). Therefore, MCa is potentially subjected to posttranslational modifications within recipient cells. Here, we report that MCa Thr(26) belongs to a consensus PKA phosphorylation site and can be phosphorylated by PKA both in vitro and after cell penetration in cellulo. Unexpectedly, phosphorylation converts MCa from positive to negative RyR1 allosteric modulator. Thr(26) phosphorylation leads to charge neutralization of Arg(24), a residue crucial for MCa agonist activity. The functional effect of Thr(26) phosphorylation is partially mimicked by aspartyl mutation. This represents the first case, to our knowledge, of both ex situ posttranslational modification and pharmacological reprogramming of a small natural cystine-rich peptide by target cells. So far, phosphorylated MCa is the first specific negative allosteric modulator of RyR1, to our knowledge, and represents a lead compound for further development of phosphatase-resistant analogs.
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10
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Vincze J, Jenes Á, Füzi M, Almássy J, Németh R, Szigeti G, Dienes B, Gaál Z, Szentesi P, Jóna I, Kertai P, Paragh G, Csernoch L. Effects of fluvastatin and coenzyme Q10 on skeletal muscle in normo- and hypercholesterolaemic rats. J Muscle Res Cell Motil 2015; 36:263-74. [PMID: 25920381 DOI: 10.1007/s10974-015-9413-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 04/21/2015] [Indexed: 10/23/2022]
Abstract
Myalgia and muscle weakness may appreciably contribute to the poor adherence to statin therapy. Although the pathomechanism of statin-induced myopathy is not completely understood, changes in calcium homeostasis and reduced coenzyme Q10 levels are hypothesized to play important roles. In our experiments, fluvastatin and/or coenzyme Q10 was administered chronically to normocholesterolaemic or hypercholaestherolaemic rats, and the modifications of the calcium homeostasis and the strength of their muscles were investigated. While hypercholesterolaemia did not change the frequency of sparks, fluvastatin increased it on muscles both from normocholesterolaemic and from hypercholesterolaemic rats. This effect, however, was not mediated by a chronic modification of the ryanodine receptor as shown by the unchanged ryanodine binding in the latter group. While coenzyme Q10 supplementation significantly reduced the frequency of the spontaneous calcium release events, it did not affect their amplitude and spatial spread in muscles from fluvastatin-treated rats. This indicates that coenzyme Q10 supplementation prevented the spark frequency increasing effect of fluvastatin without having a major effect on the amount of calcium released during individual sparks. In conclusion, we have found that fluvastatin, independently of the cholesterol level in the blood, consistently and specifically increased the frequency of calcium sparks in skeletal muscle cells, an effect which could be prevented by the addition of coenzyme Q10 to the diet. These results support theories favouring the role of calcium handling in the pathophysiology of statin-induced myopathy and provide a possible pathway for the protective effect of coenzyme Q10 in statin treated patients symptomatic of this condition.
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Affiliation(s)
- J Vincze
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, P.O. Box 22, Debrecen, 4012, Hungary
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11
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Rodríguez EG, Lefebvre R, Bodnár D, Legrand C, Szentesi P, Vincze J, Poulard K, Bertrand-Michel J, Csernoch L, Buj-Bello A, Jacquemond V. Phosphoinositide substrates of myotubularin affect voltage-activated Ca²⁺ release in skeletal muscle. Pflugers Arch 2014; 466:973-85. [PMID: 24022704 DOI: 10.1007/s00424-013-1346-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 08/29/2013] [Accepted: 08/29/2013] [Indexed: 12/19/2022]
Abstract
Skeletal muscle excitation–contraction (E–C) coupling is altered in several models of phosphatidylinositol phosphate (PtdInsP) phosphatase deficiency and ryanodine receptor activity measured in vitro was reported to be affected by certain PtdInsPs, thus prompting investigation of the physiological role of PtdInsPs in E–C coupling. We measured intracellular Ca2+ transients in voltage-clamped mouse muscle fibres microinjected with a solution containing a PtdInsP substrate (PtdIns(3,5)P2 or PtdIns(3)P) or product (PtdIns(5)P or PtdIns) of the myotubularin phosphatase MTM1. No significant change was observed in the presence of either PtdIns(5)P or PtdIns but peak SR Ca2+ release was depressed by ~30% and 50% in fibres injected with PtdIns(3,5)P2 and PtdIns(3)P, respectively, with no concurrent alteration in the membrane current signals associated with the DHPR function as well as in the voltage dependence of Ca2+ release inactivation. In permeabilized muscle fibres, the frequency of spontaneous Ca2+ release events was depressed in the presence of the three tested phosphorylated forms of PtdInsP with PtdIns(3,5)P2 being the most effective, leading to an almost complete disappearance of Ca2+ release events. Results support the possibility that pathological accumulation of MTM1 substrates may acutely depress ryanodine receptor-mediated Ca2+ release. Overexpression of a mCherry-tagged form of MTM1 in muscle fibres revealed a striated pattern consistent with the triadic area. Ca2+ release remained although unaffected by MTM1 overexpression and was also unaffected by the PtdIns-3-kinase inhibitor LY2940002, suggesting that the 3-phosphorylated PtdIns lipids active on voltage-activated Ca2+ release are inherently maintained at a low level, inefficient on Ca2+ release in normal conditions.
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12
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Bodnár D, Geyer N, Ruzsnavszky O, Oláh T, Hegyi B, Sztretye M, Fodor J, Dienes B, Balogh Á, Papp Z, Szabó L, Müller G, Csernoch L, Szentesi P. Hypermuscular mice with mutation in the myostatin gene display altered calcium signalling. J Physiol 2014; 592:1353-65. [PMID: 24445322 DOI: 10.1113/jphysiol.2013.261958] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Myostatin, a member of the transforming growth factor β family, is a potent negative regulator of skeletal muscle growth, as myostatin-deficient mice show a great increase in muscle mass. Yet the physical performance of these animals is reduced. As an explanation for this, alterations in the steps in excitation-contraction coupling were hypothesized and tested for in mice with the 12 bp deletion in the propeptide region of the myostatin precursor (Mstn(Cmpt-dl1Abc) or Cmpt). In voluntary wheel running, control C57BL/6 mice performed better than the mutant animals in both maximal speed and total distance covered. Despite the previously described lower specific force of Cmpt animals, the pCa-force relationship, determined on chemically permeabilized fibre segments, did not show any significant difference between the two mouse strains. While resting intracellular Ca(2+) concentration ([Ca(2+)]i) measured on single intact flexor digitorum brevis (FDB) muscle fibres using Fura-2 AM was similar to control (72.0 ± 1.7 vs. 78.1 ± 2.9 nM, n = 38 and 45), the amplitude of KCl-evoked calcium transients was smaller (360 ± 49 vs. 222 ± 45 nM, n = 22) in the mutant strain. Similar results were obtained using tetanic stimulation and Rhod-2 AM, which gave calcium transients that were smaller (2.42 ± 0.11 vs. 2.06 ± 0.10 ΔF/F0, n = 14 and 13, respectively) on Cmpt mice. Sarcoplasmic reticulum (SR) calcium release flux calculated from these transients showed a reduced peak (23.7 ± 3.0 vs. 15.8 ± 2.1 mM s(-1)) and steady level (5.7 ± 0.7 vs. 3.7 ± 0.5 mM s(-1)) with no change in the peak-to-steady ratio. The amplitude and spatial spread of calcium release events detected on permeabilized FDB fibres were also significantly smaller in mutant mice. These results suggest that reduced SR calcium release underlies the reduced muscle force in Cmpt animals.
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Affiliation(s)
- Dóra Bodnár
- Department of Physiology, Faculty of Medicine, Medical and Health Science Centre, University of Debrecen, PO Box 22, H-4012 Debrecen, Hungary.
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13
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Abstract
The ICK (inhibitor cystine knot) defines a large superfamily of polypeptides with high structural stability and functional diversity. Here, we describe a new scorpion venom-derived K+ channel toxin (named λ-MeuKTx-1) with an ICK fold through gene cloning, chemical synthesis, nuclear magnetic resonance spectroscopy, Ca2+ release measurements and electrophysiological recordings. λ-MeuKTx-1 was found to adopt an ICK fold that contains a three-strand anti-parallel β-sheet and a 310-helix. Functionally, this peptide selectively inhibits the Drosophila Shaker K+ channel but is not capable of activating skeletal-type Ca2+ release channels/ryanodine receptors, which is remarkably different from the previously known scorpion venom ICK peptides. The removal of two C-terminal residues of λ-MeuKTx-1 led to the loss of the inhibitory activity on the channel, whereas the C-terminal amidation resulted in the emergence of activity on four mammalian K+ channels accompanied by the loss of activity on the Shaker channel. A combination of structural and pharmacological data allows the recognition of three putative functional sites involved in channel blockade of λ-MeuKTx-1. The presence of a functional dyad in λ-MeuKTx-1 supports functional convergence among scorpion venom peptides with different folds. Furthermore, similarities in precursor organization, exon–intron structure, 3D-fold and function suggest that scorpion venom ICK-type K+ channel inhibitors and Ca2+ release channel activators share a common ancestor and their divergence occurs after speciation between buthidae and non-buthids. The structural and functional characterizations of the first scorpion venom ICK toxin with K+ channel-blocking activity sheds light on functionally divergent and convergent evolution of this conserved scaffold of ancient origin.
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Hmed B, Serria HT, Mounir ZK. Scorpion peptides: potential use for new drug development. J Toxicol 2013; 2013:958797. [PMID: 23843786 PMCID: PMC3697785 DOI: 10.1155/2013/958797] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Revised: 05/19/2013] [Accepted: 05/20/2013] [Indexed: 12/13/2022] Open
Abstract
Several peptides contained in scorpion fluids showed diverse array of biological activities with high specificities to their targeted sites. Many investigations outlined their potent effects against microbes and showed their potential to modulate various biological mechanisms that are involved in immune, nervous, cardiovascular, and neoplastic diseases. Because of their important structural and functional diversity, it is projected that scorpion-derived peptides could be used to develop new specific drugs. This review summarizes relevant findings improving their use as valuable tools for new drugs development.
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Affiliation(s)
- BenNasr Hmed
- Laboratory of Pharmacology, Medicine Faculty of Sfax, Street of Majida Boulila, 3029 Sfax, Tunisia
| | - Hammami Turky Serria
- Laboratory of Pharmacology, Medicine Faculty of Sfax, Street of Majida Boulila, 3029 Sfax, Tunisia
| | - Zeghal Khaled Mounir
- Laboratory of Pharmacology, Medicine Faculty of Sfax, Street of Majida Boulila, 3029 Sfax, Tunisia
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15
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Multiple actions of phi-LITX-Lw1a on ryanodine receptors reveal a functional link between scorpion DDH and ICK toxins. Proc Natl Acad Sci U S A 2013; 110:8906-11. [PMID: 23671114 DOI: 10.1073/pnas.1214062110] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We recently reported the isolation of a scorpion toxin named U1-liotoxin-Lw1a (U1-LITX-Lw1a) that adopts an unusual 3D fold termed the disulfide-directed hairpin (DDH) motif, which is the proposed evolutionary structural precursor of the three-disulfide-containing inhibitor cystine knot (ICK) motif found widely in animals and plants. Here we reveal that U1-LITX-Lw1a targets and activates the mammalian ryanodine receptor intracellular calcium release channel (RyR) with high (fM) potency and provides a functional link between DDH and ICK scorpion toxins. Moreover, U1-LITX-Lw1a, now described as ϕ-liotoxin-Lw1a (ϕ-LITX-Lw1a), has a similar mode of action on RyRs as scorpion calcines, although with significantly greater potency, inducing full channel openings at lower (fM) toxin concentrations whereas at higher pM concentrations increasing the frequency and duration of channel openings to a submaximal state. In addition, we show that the C-terminal residue of ϕ-LITX-Lw1a is crucial for the increase in full receptor openings but not for the increase in receptor subconductance opening, thereby supporting the two-binding-site hypothesis of scorpion toxins on RyRs. ϕ-LITX-Lw1a has potential both as a pharmacological tool and as a lead molecule for the treatment of human diseases that involve RyRs, such as malignant hyperthermia and polymorphic ventricular tachycardia.
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16
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Poillot C, Bichraoui H, Tisseyre C, Bahemberae E, Andreotti N, Sabatier JM, Ronjat M, De Waard M. Small efficient cell-penetrating peptides derived from scorpion toxin maurocalcine. J Biol Chem 2012; 287:17331-17342. [PMID: 22433862 DOI: 10.1074/jbc.m112.360628] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Maurocalcine is the first demonstrated example of an animal toxin peptide with efficient cell penetration properties. Although it is a highly competitive cell-penetrating peptide (CPP), its relatively large size of 33 amino acids and the presence of three internal disulfide bridges may hamper its development for in vitro and in vivo applications. Here, we demonstrate that several efficient CPPs can be derived from maurocalcine by replacing Cys residues by isosteric 2-aminobutyric acid residues and sequence truncation down to peptides of up to 9 residues in length. A surprising finding is that all of the truncated maurocalcine analogues possessed cell penetration properties, indicating that the maurocalcine is a highly specialized CPP. Careful examination of the cell penetration properties of the truncated analogues indicates that several maurocalcine-derived peptides should be of great interest for cell delivery applications where peptide size matters.
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Affiliation(s)
- Cathy Poillot
- INSERM U836, Grenoble Neuroscience Institute, Site Santé La Tronche, Chemin Fortuné Ferrini, BP 170, 38042 Grenoble Cedex 9, France; Université Joseph Fourier, 38041 Grenoble, France
| | - Hicham Bichraoui
- INSERM U836, Grenoble Neuroscience Institute, Site Santé La Tronche, Chemin Fortuné Ferrini, BP 170, 38042 Grenoble Cedex 9, France; Université Joseph Fourier, 38041 Grenoble, France
| | - Céline Tisseyre
- INSERM U836, Grenoble Neuroscience Institute, Site Santé La Tronche, Chemin Fortuné Ferrini, BP 170, 38042 Grenoble Cedex 9, France; Université Joseph Fourier, 38041 Grenoble, France
| | - Eloi Bahemberae
- INSERM U836, Grenoble Neuroscience Institute, Site Santé La Tronche, Chemin Fortuné Ferrini, BP 170, 38042 Grenoble Cedex 9, France; Université Joseph Fourier, 38041 Grenoble, France
| | | | | | - Michel Ronjat
- INSERM U836, Grenoble Neuroscience Institute, Site Santé La Tronche, Chemin Fortuné Ferrini, BP 170, 38042 Grenoble Cedex 9, France; Université Joseph Fourier, 38041 Grenoble, France
| | - Michel De Waard
- INSERM U836, Grenoble Neuroscience Institute, Site Santé La Tronche, Chemin Fortuné Ferrini, BP 170, 38042 Grenoble Cedex 9, France; Université Joseph Fourier, 38041 Grenoble, France; Smartox Biotechnologies, Biopolis, 5 Avenue du Grand Sablon, 38700 La Tronche, France.
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17
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Both basic and acidic amino acid residues of IpTx(a) are involved in triggering substate of RyR1. J Biomed Biotechnol 2011; 2011:386384. [PMID: 22007141 PMCID: PMC3192407 DOI: 10.1155/2011/386384] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 08/05/2011] [Accepted: 08/10/2011] [Indexed: 12/02/2022] Open
Abstract
Imperatoxin A (IpTxa) is known to modify the gating of skeletal ryanodine receptor (RyR1). In this paper, the ability of charged aa residues of IpTxa to induce substate of native RyR1 in HSR was examined. Our results show that the basic residues (e.g., Lys19, Lys20, Lys22, Arg23, and Arg24) are important for producing substate of RyR1. In addition, other basic residues (e.g., Lys30, Arg31, and Arg33) near the C-terminus and some acidic residues (e.g., Glu29, Asp13, and Asp2) are also involved in the generation of substate. Residues such as Lys8 and Thr26 may be involved in the self-regulation of substate of RyR1, since alanine substitution of the aa residues led to a drastic conversion to the substate. The modifications of the channel gating by the wild-type and mutant toxins were similar in purified RyR1. Taken together, the specific charge distributions on the surface of IpTxa are essential for regulation of the channel gating of RyR1.
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18
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Poillot C, Dridi K, Bichraoui H, Pêcher J, Alphonse S, Douzi B, Ronjat M, Darbon H, De Waard M. D-Maurocalcine, a pharmacologically inert efficient cell-penetrating peptide analogue. J Biol Chem 2010; 285:34168-80. [PMID: 20610396 DOI: 10.1074/jbc.m110.104919] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Maurocalcine has been the first demonstrated animal toxin acting as a cell-penetrating peptide. Although it possesses competitive advantages, its use as a cell-penetrating peptide (CPP) requires that analogues be developed that lack its characteristic pharmacological activity on ryanodine-sensitive calcium channels without affecting its cell-penetrating and vector efficiencies. Here, we present the synthesis, three-dimensional (1)H NMR structure, and activity of D-maurocalcine. We demonstrate that it possesses all of the desired features for an excellent CPP: preserved structure, lack of pharmacological action, conserved vector properties, and absence of cell toxicity. This is the first report of a folded/oxidized animal toxin in its D-diastereomer conformation for use as a CPP. The protease resistance of this new peptide analogue, combined with its efficient cell penetration at concentrations devoid of cell toxicity, suggests that D-maurocalcine should be an excellent vector for in vivo applications.
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Affiliation(s)
- Cathy Poillot
- Grenoble Institute of Neuroscience, INSERM U836, Site Santé de la Tronche, Bâtiment Edmond J Safra, Chemin Fortuné Ferrini, BP170, 38042 Grenoble Cedex 9, France
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19
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Szabó LZ, Vincze J, Csernoch L, Szentesi P. Improved spark and ember detection using stationary wavelet transforms. J Theor Biol 2010; 264:1279-92. [PMID: 20382167 DOI: 10.1016/j.jtbi.2010.04.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 03/31/2010] [Accepted: 04/06/2010] [Indexed: 11/27/2022]
Abstract
Calcium sparks and embers are localized intracellular events of calcium release in muscle cells studied frequently by confocal microscopy using line-scan imaging. The large quantity of images and large number of events require automatic detection procedures based on signal processing methods. In the past decades these methods were based on thresholding procedures. Although, recently, wavelet transforms were also introduced, they have not become widespread. We have implemented a set of algorithms based on one- and two-dimensional versions of the à trous wavelet transform. The algorithms were used to perform spike filtering, denoising and detection procedures. Due to the dependence of the algorithms on user adjustable parameters, their effect on the efficiency of the algorithm was studied in detail. We give methods to avoid false positive detections which are the consequence of the background noise in confocal images. In order to establish the efficiency and reliability of the algorithms, various tests were performed on artificial and experimental images. Spark parameters (amplitude, full width-at-half maximum) calculated using the traditional and the wavelet methods were compared. We found that the latter method is capable of identifying more events with better accuracy on experimental images. Furthermore, we extended the wavelet-based transform from calcium sparks to long-lasting small-amplitude events as calcium embers. The method not only solved their automatic detection but enabled the identification of events with small amplitude that otherwise escaped the eye, rendering the determination of their characteristic parameters more accurate.
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Affiliation(s)
- László Zsolt Szabó
- Department of Physiology, Medical and Health Science Centre, University of Debrecen, Debrecen, Hungary
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20
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Jayagopal A, Su YR, Blakemore JL, Linton MF, Fazio S, Haselton FR. Quantum dot mediated imaging of atherosclerosis. NANOTECHNOLOGY 2009; 20:165102. [PMID: 19420562 PMCID: PMC2718756 DOI: 10.1088/0957-4484/20/16/165102] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The progression of atherosclerosis is associated with leukocyte infiltration within lesions. We describe a technique for the ex vivo imaging of cellular recruitment in atherogenesis which utilizes quantum dots (QD) to color-code different cell types within lesion areas. Spectrally distinct QD were coated with the cell-penetrating peptide maurocalcine to fluorescently-label immunomagnetically isolated monocyte/macrophages and T lymphocytes. QD-maurocalcine bioconjugates labeled both cell types with a high efficiency, preserved cell viability, and did not perturb native leukocyte function in cytokine release and endothelial adhesion assays. QD-labeled monocyte/macrophages and T lymphocytes were reinfused in an ApoE(-/-) mouse model of atherosclerosis and age-matched controls and tracked for up to four weeks to investigate the incorporation of cells within aortic lesion areas, as determined by oil red O (ORO) and immunofluorescence ex vivo staining. QD-labeled cells were visible in atherosclerotic plaques within two days of injection, and the two cell types colocalized within areas of subsequent ORO staining. Our method for tracking leukocytes in lesions enables high signal-to-noise ratio imaging of multiple cell types and biomarkers simultaneously within the same specimen. It also has great utility in studies aimed at investigating the role of distinct circulating leukocyte subsets in plaque development and progression.
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Affiliation(s)
- Ashwath Jayagopal
- Department of Biomedical Engineering, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Yan Ru Su
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - John L Blakemore
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - MacRae F Linton
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Sergio Fazio
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Frederick R Haselton
- Department of Biomedical Engineering, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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