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Rao STRB, Turek I, Ratcliffe J, Beckham S, Cianciarulo C, Adil SSBMY, Kettle C, Whelan DR, Irving HR. 5-HT 3 Receptors on Mitochondria Influence Mitochondrial Function. Int J Mol Sci 2023; 24:ijms24098301. [PMID: 37176009 PMCID: PMC10179570 DOI: 10.3390/ijms24098301] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 04/30/2023] [Accepted: 05/01/2023] [Indexed: 05/15/2023] Open
Abstract
The 5-hydroxytryptamine 3 (5-HT3) receptor belongs to the pentameric ligand-gated cation channel superfamily. Humans have five different 5-HT3 receptor subunits: A to E. The 5-HT3 receptors are located on the cell membrane, but a previous study suggested that mitochondria could also contain A subunits. In this article, we explored the distribution of 5-HT3 receptor subunits in intracellular and cell-free mitochondria. Organelle prediction software supported the localization of the A and E subunits on the inner membrane of the mitochondria. We transiently transfected HEK293T cells that do not natively express the 5-HT3 receptor with an epitope and fluorescent protein-tagged 5HT3A and 5HT3E subunits. Fluorescence microscopy and cell fractionation indicated that both subunits, A and E, localized to the mitochondria, while transmission electron microscopy revealed the location of the subunits on the mitochondrial inner membrane, where they could form heteromeric complexes. Cell-free mitochondria isolated from cell culture media colocalized with the fluorescent signal for A subunits. The presence of A and E subunits influenced changes in the membrane potential and mitochondrial oxygen consumption rates upon exposure to serotonin; this was inhibited by pre-treatment with ondansetron. Therefore, it is likely that the 5-HT3 receptors present on mitochondria directly impact mitochondrial function and that this may have therapeutic implications.
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Affiliation(s)
- Santosh T R B Rao
- La Trobe Institute for Molecular Science, La Trobe University, P.O. Box 199, Bendigo, VIC 3552, Australia
- Department of Rural Clinical Sciences, La Trobe University, P.O. Box 199, Bendigo, VIC 3552, Australia
| | - Ilona Turek
- La Trobe Institute for Molecular Science, La Trobe University, P.O. Box 199, Bendigo, VIC 3552, Australia
- Department of Rural Clinical Sciences, La Trobe University, P.O. Box 199, Bendigo, VIC 3552, Australia
| | - Julian Ratcliffe
- La Trobe Institute for Molecular Science, La Trobe University, P.O. Box 199, Bendigo, VIC 3552, Australia
- Bio Imaging Platform, La Trobe University, Kingsbury Dr, Bundoora, VIC 3086, Australia
| | - Simone Beckham
- Regional Science Operations, La Trobe University, P.O. Box 199, Bendigo, VIC 3552, Australia
| | - Cassandra Cianciarulo
- La Trobe Institute for Molecular Science, La Trobe University, P.O. Box 199, Bendigo, VIC 3552, Australia
- Department of Rural Clinical Sciences, La Trobe University, P.O. Box 199, Bendigo, VIC 3552, Australia
| | - Siti S B M Y Adil
- Department of Rural Clinical Sciences, La Trobe University, P.O. Box 199, Bendigo, VIC 3552, Australia
| | - Christine Kettle
- La Trobe Institute for Molecular Science, La Trobe University, P.O. Box 199, Bendigo, VIC 3552, Australia
- Department of Rural Clinical Sciences, La Trobe University, P.O. Box 199, Bendigo, VIC 3552, Australia
| | - Donna R Whelan
- La Trobe Institute for Molecular Science, La Trobe University, P.O. Box 199, Bendigo, VIC 3552, Australia
- Department of Rural Clinical Sciences, La Trobe University, P.O. Box 199, Bendigo, VIC 3552, Australia
| | - Helen R Irving
- La Trobe Institute for Molecular Science, La Trobe University, P.O. Box 199, Bendigo, VIC 3552, Australia
- Department of Rural Clinical Sciences, La Trobe University, P.O. Box 199, Bendigo, VIC 3552, Australia
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Phylogenetic analyses of 5-hydroxytryptamine 3 (5-HT3) receptors in Metazoa. PLoS One 2023; 18:e0281507. [PMID: 36857360 PMCID: PMC9977066 DOI: 10.1371/journal.pone.0281507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 01/24/2023] [Indexed: 03/02/2023] Open
Abstract
The 5-hydroxytrptamine 3 (5-HT3) receptor is a member of the 'Cys-loop' family and the only pentameric ligand gated ion channel among the serotonin receptors. 5-HT3 receptors play an important role in controlling growth, development, and behaviour in animals. Several 5-HT3 receptor antagonists are used to treat diseases (e.g., irritable bowel syndrome, nausea and emesis). Humans express five different subunits (A-E) enabling a variety of heteromeric receptors to form but all contain 5HT3A subunits. However, the information available about the 5-HT3 receptor subunit occurrence among the metazoan lineages is minimal. In the present article we searched for 5-HT3 receptor subunit homologs from different phyla in Metazoa. We identified more than 1000 5-HT3 receptor subunits in Metazoa in different phyla and undertook simultaneous phylogenetic analysis of 526 5HT3A, 358 5HT3B, 239 5HT3C, 70 5HT3D, and 173 5HT3E sequences. 5-HT3 receptor subunits were present in species belonging to 11 phyla: Annelida, Arthropoda, Chordata, Cnidaria, Echinodermata, Mollusca, Nematoda, Orthonectida, Platyhelminthes, Rotifera and Tardigrada. All subunits were most often identified in Chordata phylum which was strongly represented in searches. Using multiple sequence alignment, we investigated variations in the ligand binding region of the 5HT3A subunit protein sequences in the metazoan lineage. Several critical amino acid residues important for ligand binding (common structural features) are commonly present in species from Nematoda and Platyhelminth gut parasites through to Chordata. Collectively, this better understanding of the 5-HT3 receptor evolutionary patterns raises possibilities of future pharmacological challenges facing Metazoa including effects on parasitic and other species in ecosystems that contain 5-HT3 receptor ligands.
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Rodriguez Araujo N, Hernando G, Corradi J, Bouzat C. The nematode serotonin-gated chloride channel MOD-1: A novel target for anthelmintic therapy. J Biol Chem 2022; 298:102356. [PMID: 35952761 PMCID: PMC9471462 DOI: 10.1016/j.jbc.2022.102356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 07/26/2022] [Accepted: 07/28/2022] [Indexed: 10/29/2022] Open
Abstract
Anthelmintics are used to treat human and veterinary parasitic diseases, as well as to reduce crop and livestock production loss associated with parasitosis. The free-living nematode Caenorhabditis elegans, a model system for anthelmintic drug discovery, has a serotonin (5-HT)-gated chloride channel, MOD-1, which belongs to the Cys-loop receptor family and modulates locomotory and behavioral functions. Since MOD-1 is unique to nematodes, it is emerging as an attractive anthelmintic drug target, but details of MOD-1 function are unclear. Here, we revealed novel aspects of MOD-1 function from the molecular level to the organism level and identified compounds targeting this receptor, which may provide new directions for anthelmintic drug discovery. We used whole-cell current recordings from heterologously expressed MOD-1 to show that tryptamine, a weak partial agonist of vertebrate 5-HT3 receptors, efficaciously activates MOD-1. A screen for modulators revealed that GABAergic ligands piperazine and muscimol reduce 5-HT-elicited currents, thus identifying novel MOD-1 allosteric inhibitors. Next, we performed locomotor activity assays, and we found 5-HT and tryptamine rapidly decrease worm motility, which is reversible only at low 5-HT concentrations. Mutants lacking MOD-1 are partially resistant to both drugs, demonstrating its key role in locomotion. Acting as an antagonist of MOD-1, we showed piperazine reduces the locomotor effects of exogenous 5-HT. Therefore, tryptamine- and piperazine-derived compounds, acting at MOD-1 through different molecular mechanisms, emerge as promising anthelmintic agents. This study enhances our knowledge of the function and drug selectivity of Cys-loop receptors and postulates MOD-1 as a potential target for anthelmintic therapy.
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Affiliation(s)
- Noelia Rodriguez Araujo
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina
| | - Guillermina Hernando
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina
| | - Jeremías Corradi
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina.
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Dalziel JE, Spencer NJ, Young W. Microbial signalling in colonic motility. Int J Biochem Cell Biol 2021; 134:105963. [PMID: 33636395 DOI: 10.1016/j.biocel.2021.105963] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/31/2021] [Accepted: 02/19/2021] [Indexed: 12/20/2022]
Abstract
Sensory nerve endings within the wall of the gastrointestinal (GI) tract may respond to bacterial signalling, providing the basis for key biological processes that underlie intestinal motility and microbial homeostasis. Enteric neurons and smooth muscle cells are well known to express an array of receptors, including G-protein coupled receptors and ligand-gated ion channels, that can sense chemical ligands and other bacterially-derived substances. These include short chain fatty acids, secondary bile acids and lipopolysaccharide. For neural detection of microbial activators to occur, luminal substances must first interact with enterocytes for direct signalling or cross paracellularly. Recent studies indicate that bacterial-derived microvesicles can cross the gut epithelial barrier and affect motility. This suggests a possible intercellular communication pathway between the GI tract and the ENS. We explore the idea that bacterial microvesicles can behave as a delivery package for communication between microbe and host.
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Affiliation(s)
- Julie E Dalziel
- Smart Foods Innovation Centre of Excellence, AgResearch, Palmerston North, New Zealand.
| | - Nick J Spencer
- Discipline of Physiology, College of Medicine and Public Health, Flinders University, School of Medicine, Adelaide, SA, Australia
| | - Wayne Young
- Smart Foods Innovation Centre of Excellence, AgResearch, Palmerston North, New Zealand
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