1
|
Nakayama A, Watanabe M, Yamashiro R, Kuroyanagi H, Matsuyama HJ, Oshima A, Mori I, Nakano S. A hyperpolarizing neuron recruits undocked innexin hemichannels to transmit neural information in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2024; 121:e2406565121. [PMID: 38753507 PMCID: PMC11127054 DOI: 10.1073/pnas.2406565121] [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: 04/04/2024] [Accepted: 04/19/2024] [Indexed: 05/18/2024] Open
Abstract
While depolarization of the neuronal membrane is known to evoke the neurotransmitter release from synaptic vesicles, hyperpolarization is regarded as a resting state of chemical neurotransmission. Here, we report that hyperpolarizing neurons can actively signal neural information by employing undocked hemichannels. We show that UNC-7, a member of the innexin family in Caenorhabditis elegans, functions as a hemichannel in thermosensory neurons and transmits temperature information from the thermosensory neurons to their postsynaptic interneurons. By monitoring neural activities in freely behaving animals, we find that hyperpolarizing thermosensory neurons inhibit the activity of the interneurons and that UNC-7 hemichannels regulate this process. UNC-7 is required to control thermotaxis behavior and functions independently of synaptic vesicle exocytosis. Our findings suggest that innexin hemichannels mediate neurotransmission from hyperpolarizing neurons in a manner that is distinct from the synaptic transmission, expanding the way of neural circuitry operations.
Collapse
Affiliation(s)
- Airi Nakayama
- Department of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi464-8602, Japan
| | - Masakatsu Watanabe
- Laboratory of Pattern Formation, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka565-0871, Japan
| | - Riku Yamashiro
- Department of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi464-8602, Japan
| | - Hiroo Kuroyanagi
- Department of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi464-8602, Japan
| | - Hironori J. Matsuyama
- Group of Molecular Neurobiology, Neuroscience Institute, Graduate School of Science, Nagoya University, Nagoya, Aichi464-8602, Japan
| | - Atsunori Oshima
- Department of Basic Biology, Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya464-8601, Japan
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Aichi464-8601, Japan
- Molecular Physiology Division, Institute for Glyco-core Research, Nagoya University, Chikusa-ku, Nagoya464-8601, Japan
- Division of Innovative Modality Development, Center for One Medicine Innovative Translational Research, Gifu University Institute for Advanced Study, Gifu501-11193, Japan
| | - Ikue Mori
- Group of Molecular Neurobiology, Neuroscience Institute, Graduate School of Science, Nagoya University, Nagoya, Aichi464-8602, Japan
- Chinese Institute for Brain Research, Changping District, Beijing102206, China
| | - Shunji Nakano
- Department of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi464-8602, Japan
- Group of Molecular Neurobiology, Neuroscience Institute, Graduate School of Science, Nagoya University, Nagoya, Aichi464-8602, Japan
| |
Collapse
|
2
|
Luo Y, Zheng S, Xiao W, Zhang H, Li Y. Pannexins in the musculoskeletal system: new targets for development and disease progression. Bone Res 2024; 12:26. [PMID: 38705887 PMCID: PMC11070431 DOI: 10.1038/s41413-024-00334-8] [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: 12/08/2023] [Revised: 03/04/2024] [Accepted: 04/01/2024] [Indexed: 05/07/2024] Open
Abstract
During cell differentiation, growth, and development, cells can respond to extracellular stimuli through communication channels. Pannexin (Panx) family and connexin (Cx) family are two important types of channel-forming proteins. Panx family contains three members (Panx1-3) and is expressed widely in bone, cartilage and muscle. Although there is no sequence homology between Panx family and Cx family, they exhibit similar configurations and functions. Similar to Cxs, the key roles of Panxs in the maintenance of physiological functions of the musculoskeletal system and disease progression were gradually revealed later. Here, we seek to elucidate the structure of Panxs and their roles in regulating processes such as osteogenesis, chondrogenesis, and muscle growth. We also focus on the comparison between Cx and Panx. As a new key target, Panxs expression imbalance and dysfunction in muscle and the therapeutic potentials of Panxs in joint diseases are also discussed.
Collapse
Affiliation(s)
- Yan Luo
- Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China
- Department of Clinical Medicine, Xiangya Medicine School, Central South University, Changsha, Hunan, 410008, China
| | - Shengyuan Zheng
- Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China
- Department of Clinical Medicine, Xiangya Medicine School, Central South University, Changsha, Hunan, 410008, China
| | - Wenfeng Xiao
- Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China
| | - Hang Zhang
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.
| | - Yusheng Li
- Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China.
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China.
| |
Collapse
|
3
|
Tetenborg S, Ariakia F, Martinez-Soler E, Shihabeddin E, Lazart IC, Miller AC, O’Brien J. Trafficking of Connexin36 (Cx36) in the early secretory pathway. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.25.586643. [PMID: 38585986 PMCID: PMC10996632 DOI: 10.1101/2024.03.25.586643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Gap junctions formed by the major neuronal connexin Cx36 function as electrical synapses in the nervous system and provide unique functions such as synchronizing activities or network oscillations. Although the physiological significance of electrical synapses for neuronal networks is well established, little is known about the pathways that regulate the transport of its main component: Cx36. Here we have used HEK293T cells as an expression system in combination with siRNA and BioID screens to study the transition of Cx36 from the ER to the cis Golgi. Our data indicate that the C-terminal tip of Cx36 is a key factor in this process, mediating binding interactions with two distinct components in the early secretory pathway: the COPII complex and the Golgi stacking protein Grasp55. The C-terminal amino acid valine serves as an ER export signal to recruit COPII cargo receptors Sec24A/B/C at ER exit sites, whereas the PDZ binding motif "SAYV" mediates an interaction with Grasp55. These two interactions have opposing effects in their respective compartments. While Sec24 subunits carry Cx36 out of the ER, Grasp55 stabilizes Cx36 in the Golgi as shown in over expression experiments. These early regulatory steps of Cx36 are expected to be essential for the formation, function, regulation and plasticity of electrical synapses in the developing and mature nervous system.
Collapse
Affiliation(s)
| | - Fatemeh Ariakia
- College of Optometry, University of Houston, Houston, TX, USA
- Contributed equally
| | | | - Eyad Shihabeddin
- College of Optometry, University of Houston, Houston, TX, USA
- MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Ignacio Cebrian Lazart
- Instituto de Histología y Embriología de Mendoza (IHEM)-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza 5500, Argentina
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
| | - Adam C. Miller
- Institute of Neuroscience, Department of Biology, University of Oregon, Eugene, OR, USA
| | - John O’Brien
- College of Optometry, University of Houston, Houston, TX, USA
| |
Collapse
|
4
|
Xing C, Wang M, Chen Z, Li Y, Zhou X, Wang L, Zhong Y, Li W, Shen X, Gao H, Wang P. Morphological and Molecular Changes during Limb Regeneration of the Exopalaemon carinicauda. Animals (Basel) 2024; 14:685. [PMID: 38473070 DOI: 10.3390/ani14050685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Revised: 02/16/2024] [Accepted: 02/20/2024] [Indexed: 03/14/2024] Open
Abstract
With the increase in breeding density of Exopalaemon carinicauda, appendage breakage may occur, which seriously affects survival and economic benefits. To study the limb regeneration process of E. carinicauda, we induced autotomy of the pereopods. After a period of time, wound swelling disappeared, the pigment gradually accumulated, and a tawny film subsequently formed in the wound. The healing period of the wound occurred 24 h after autotomy, and the blastema formation stage occurred 48 h after autotomy. After 4 days of cutting, the limb buds began to differentiate, grow, and expand rapidly, and this process lasted approximately 15 days. Microscopic observations revealed significant changes in the type and number of associated cells including outer epithelial cells, granulocytes, embryonic cells, columnar epidermal cells, elongated cells, and blastoma cells, during the process from limb fracture to regeneration. A comparative transcriptome analysis identified 1415 genes differentially expressed between the J0h (0 h post autotomy) and J18h (18 h post autotomy), and 3952 and 4366 differentially expressed genes for J0 and J14d (14 days post autotomy) and J18h and J14d, respectively. Some of these genes may be related to muscle growth or molting, as indicated by the presence of troponin C, chitinase, actin, innexin, and cathepsin L. As a functional gene involved in epidermal formation, the mRNA expression level of the innexin inx2 in the pereopod of E. carinicauda changed significantly in the experimental groups (p < 0.05). The results of this study contribute to existing knowledge of regeneration mechanisms in crustaceans.
Collapse
Affiliation(s)
- Chaofan Xing
- Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China
- Co-Innovation Center of Jiangsu Marine Bio-Industry Technology, Jiangsu Ocean University, Lianyungang 222005, China
| | - Mintao Wang
- Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China
| | - Zhenxiang Chen
- Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China
| | - Yong Li
- Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China
| | - Xinlei Zhou
- Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China
| | - Lei Wang
- Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China
| | - Yao Zhong
- Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China
| | - Wenjia Li
- Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China
| | - Xin Shen
- Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China
- Co-Innovation Center of Jiangsu Marine Bio-Industry Technology, Jiangsu Ocean University, Lianyungang 222005, China
- Jiangsu Institute of Marine Resources Development, Jiangsu Ocean University, Lianyungang 222005, China
| | - Huan Gao
- Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China
- Co-Innovation Center of Jiangsu Marine Bio-Industry Technology, Jiangsu Ocean University, Lianyungang 222005, China
- Jiangsu Institute of Marine Resources Development, Jiangsu Ocean University, Lianyungang 222005, China
- The Jiangsu Provincial Infrastructure for Conservation and Utilization of Agricultural Germplasm, Nanjing 210014, China
| | - Panpan Wang
- Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China
- Co-Innovation Center of Jiangsu Marine Bio-Industry Technology, Jiangsu Ocean University, Lianyungang 222005, China
- Jiangsu Institute of Marine Resources Development, Jiangsu Ocean University, Lianyungang 222005, China
- The Jiangsu Provincial Infrastructure for Conservation and Utilization of Agricultural Germplasm, Nanjing 210014, China
| |
Collapse
|
5
|
Sherman D, Harel D. Deciphering the underlying mechanisms of the pharyngeal pumping motions in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2024; 121:e2302660121. [PMID: 38315866 PMCID: PMC10873627 DOI: 10.1073/pnas.2302660121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 12/29/2023] [Indexed: 02/07/2024] Open
Abstract
The pharynx of the nematode Caenorhabditis elegans is a neuromuscular organ that exhibits typical pumping motions, which result in the intake of food particles from the environment. In-depth inspection reveals slightly different dynamics at the various pharyngeal areas, rather than synchronous pumping motions of the whole organ, which are important for its effective functioning. While the different pumping dynamics are well characterized, the underlying mechanisms that generate them are not known. In this study, the C. elegans pharynx was modeled in a bottom-up fashion, including all of the underlying biological processes that lead to, and including, its end function, food intake. The mathematical modeling of all processes allowed performing comprehensive, quantitative analyses of the system as a whole. Our analyses provided detailed explanations for the various pumping dynamics generated at the different pharyngeal areas; a fine-resolution description of muscle dynamics, both between and within different pharyngeal areas; a quantitative assessment of the values of many parameters of the system that are unavailable in the literature; and support for a functional role of the marginal cells, which are currently assumed to mainly have a structural role in the pharynx. In addition, our model predicted that in tiny organisms such as C. elegans, the generation of long-lasting action potentials must involve ions other than calcium. Our study exemplifies the power of mathematical models, which allow a more accurate, higher-resolution inspection of the studied system, and an easier and faster execution of in silico experiments than feasible in the lab.
Collapse
Affiliation(s)
- Dana Sherman
- Department of Computer Science and Applied Mathematics, Faculty of Mathematics and Computer Science, The Weizmann Institute of Science, Rehovot76100, Israel
| | - David Harel
- Department of Computer Science and Applied Mathematics, Faculty of Mathematics and Computer Science, The Weizmann Institute of Science, Rehovot76100, Israel
| |
Collapse
|
6
|
Ho KYL, An K, Carr RL, Dvoskin AD, Ou AYJ, Vogl W, Tanentzapf G. Maintenance of hematopoietic stem cell niche homeostasis requires gap junction-mediated calcium signaling. Proc Natl Acad Sci U S A 2023; 120:e2303018120. [PMID: 37903259 PMCID: PMC10636368 DOI: 10.1073/pnas.2303018120] [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: 02/22/2023] [Accepted: 09/11/2023] [Indexed: 11/01/2023] Open
Abstract
Regulation of stem cells requires coordination of the cells that make up the stem cell niche. Here, we describe a mechanism that allows communication between niche cells to coordinate their activity and shape the signaling environment surrounding resident stem cells. Using the Drosophila hematopoietic organ, the lymph gland, we show that cells of the hematopoietic niche, the posterior signaling center (PSC), communicate using gap junctions (GJs) and form a signaling network. This network allows PSC cells to exchange Ca2+ signals repetitively which regulate the hematopoietic niche. Disruption of Ca2+ signaling in the PSC or the GJ-mediated network connecting niche cells causes dysregulation of the PSC and blood progenitor differentiation. Analysis of PSC-derived cell signaling shows that the Hedgehog pathway acts downstream of GJ-mediated Ca2+ signaling to modulate the niche microenvironment. These data show that GJ-mediated communication between hematopoietic niche cells maintains their homeostasis and consequently controls blood progenitor behavior.
Collapse
Affiliation(s)
- Kevin Y. L. Ho
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BCV6T 1Z3, Canada
| | - Kevin An
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BCV6T 1Z3, Canada
| | - Rosalyn L. Carr
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BCV6T 1Z3, Canada
- School of Biomedical Engineering, University of British Columbia, Vancouver, BCV6T 1Z3, Canada
- British Columbia Children’s Hospital Research Institute, British Columbia Children’s Hospital, Vancouver, BCV5Z 4H4, Canada
| | - Alexandra D. Dvoskin
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BCV6T 1Z3, Canada
| | - Annie Y. J. Ou
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BCV6T 1Z3, Canada
- School of Kinesiology, University of British Columbia, Vancouver, BCV6T 1Z1, Canada
| | - Wayne Vogl
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BCV6T 1Z3, Canada
| | - Guy Tanentzapf
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BCV6T 1Z3, Canada
| |
Collapse
|
7
|
Güiza J, Solís F, Valenzuela B, Arancibia D, Zamorano P, González J, Saavedra J, Neely A, Salgado M, Martínez AD, Sáez JC, Vega JL. Unnexin is a protein subunit of a large-pore channel expressed by unicellular organisms. Proc Natl Acad Sci U S A 2023; 120:e2307898120. [PMID: 37487087 PMCID: PMC10400985 DOI: 10.1073/pnas.2307898120] [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: 05/10/2023] [Accepted: 06/23/2023] [Indexed: 07/26/2023] Open
Abstract
Cells of vertebrate and invertebrate organisms express proteins specialized in membrane channel-based cell-cell communication that are absent in unicellular organisms. We recently described the prediction of some members of the large-pore channel family in kinetoplastids, consisting of proteins called unnexins, which share several structural features with innexin and pannexin proteins. Here, we demonstrated that the unnexin1 protein (Unx1) is delivered to the cell membrane, displaying a topology consisting of four transmembrane domains with C and N termini on the cytoplasmic side and form large-pore channels that are permeable to small molecules. Low extracellular Ca2+/Mg2+ levels or extracellular alkalinization, but not mechanical stretching, increases channel activity. The Unx1 channel mediates the influx of Ca2+ and does not form intercellular dye coupling between HeLa Unx1 transfected cells. Unx1 channel function was further evidenced by its ability to mediate ionic currents when expressed in Xenopus oocytes. Downregulation of Unx1 mRNA with morpholine contains Trypanosoma cruzi invasion. Phylogenetic analysis revealed the presence of Unx1 homologs in other protozoan parasites, suggesting a conserved function for these channel parasites in other protists. Our data demonstrate that Unx1 forms large-pore membrane channels, which may serve as a diffusional pathway for ions and small molecules that are likely to be metabolic substrates or waste products, and signaling autocrine and paracrine molecules that could be involved in cell invasion. As morpholinos-induced downregulation of Unx1 reduces the infectivity of trypomastigotes, the Unx1 channels might be an attractive target for developing trypanocide drugs.
Collapse
Affiliation(s)
- Juan Güiza
- Laboratory of Gap Junction Proteins and Parasitic Diseases (GaPaL), Instituto Antofagasta, Universidad de Antofagasta, Antofagasta1240000, Chile
| | - Francisco Solís
- Laboratorio de Microorganismos Extremófilos, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta1240000, Chile
| | - Bernardita Valenzuela
- Laboratorio de Microorganismos Extremófilos, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta1240000, Chile
| | - Duxan Arancibia
- Laboratorio de Microorganismos Extremófilos, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta1240000, Chile
| | - Pedro Zamorano
- Laboratorio de Microorganismos Extremófilos, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta1240000, Chile
| | - Jorge González
- Departamento de Tecnología Médica, Unidad de Parasitología Molecular, Facultad Ciencias de la Salud, Universidad de Antofagasta, Antofagasta1240000, Chile
| | - Jonathan Saavedra
- Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso2381850, Chile
| | - Alan Neely
- Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso2381850, Chile
| | - Magdiel Salgado
- Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso2381850, Chile
| | - Agustín D. Martínez
- Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso2381850, Chile
| | - Juan C. Sáez
- Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso2381850, Chile
| | - José L. Vega
- Laboratory of Gap Junction Proteins and Parasitic Diseases (GaPaL), Instituto Antofagasta, Universidad de Antofagasta, Antofagasta1240000, Chile
- Departamento Biomédico, Facultad de Ciencias de la Salud, Universidad de Antofagasta, Antofagasta1240000, Chile
| |
Collapse
|
8
|
Cárdenas-García SP, Ijaz S, Pereda AE. The components of an electrical synapse as revealed by expansion microscopy of a single synaptic contact. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.25.550347. [PMID: 37546897 PMCID: PMC10402082 DOI: 10.1101/2023.07.25.550347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Most nervous systems combine both transmitter-mediated and direct cell-cell communication, known as 'chemical' and 'electrical' synapses, respectively. Chemical synapses can be identified by their multiple structural components. Electrical synapses are, on the other hand, generally defined by the presence of a 'gap junction' (a cluster of intercellular channels) between two neuronal processes. However, while gap junctions provide the communicating mechanism, it is unknown whether electrical transmission requires the contribution of additional cellular structures. We investigated this question at identifiable single synaptic contacts on the zebrafish Mauthner cells, at which gap junctions coexist with specializations for neurotransmitter release and where the contact defines the anatomical limits of a synapse. Expansion microscopy of these contacts revealed a detailed map of the incidence and spatial distribution of proteins pertaining to various synaptic structures. Multiple gap junctions of variable size were identified by the presence of their molecular components. Remarkably, most of the synaptic contact's surface was occupied by interleaving gap junctions and components of adherens junctions, suggesting a close functional association between these two structures. In contrast, glutamate receptors were confined to small peripheral portions of the contact, indicating that most of the synaptic area works as an electrical synapse. Thus, our results revealed the overarching organization of an electrical synapse that operates with not one, but multiple gap junctions, in close association with structural and signaling molecules known to be components of AJs. The relationship between these intercellular structures will aid in establishing the boundaries of electrical synapses found throughout animal connectomes and provide insight into the structural organization and functional diversity of electrical synapses.
Collapse
Affiliation(s)
- Sandra P. Cárdenas-García
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Sundas Ijaz
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Alberto E. Pereda
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| |
Collapse
|
9
|
Hürkey S, Niemeyer N, Schleimer JH, Ryglewski S, Schreiber S, Duch C. Gap junctions desynchronize a neural circuit to stabilize insect flight. Nature 2023:10.1038/s41586-023-06099-0. [PMID: 37225999 DOI: 10.1038/s41586-023-06099-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 04/18/2023] [Indexed: 05/26/2023]
Abstract
Insect asynchronous flight is one of the most prevalent forms of animal locomotion used by more than 600,000 species. Despite profound insights into the motor patterns1, biomechanics2,3 and aerodynamics underlying asynchronous flight4,5, the architecture and function of the central-pattern-generating (CPG) neural network remain unclear. Here, on the basis of an experiment-theory approach including electrophysiology, optophysiology, Drosophila genetics and mathematical modelling, we identify a miniaturized circuit solution with unexpected properties. The CPG network consists of motoneurons interconnected by electrical synapses that, in contrast to doctrine, produce network activity splayed out in time instead of synchronized across neurons. Experimental and mathematical evidence support a generic mechanism for network desynchronization that relies on weak electrical synapses and specific excitability dynamics of the coupled neurons. In small networks, electrical synapses can synchronize or desynchronize network activity, depending on the neuron-intrinsic dynamics and ion channel composition. In the asynchronous flight CPG, this mechanism translates unpatterned premotor input into stereotyped neuronal firing with fixed sequences of cell activation that ensure stable wingbeat power and, as we show, is conserved across multiple species. Our findings prove a wider functional versatility of electrical synapses in the dynamic control of neural circuits and highlight the relevance of detecting electrical synapses in connectomics.
Collapse
Affiliation(s)
- Silvan Hürkey
- Institute of Developmental Biology and Neurobiology (iDN), Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Nelson Niemeyer
- Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Berlin, Germany
| | | | - Stefanie Ryglewski
- Institute of Developmental Biology and Neurobiology (iDN), Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Susanne Schreiber
- Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Berlin, Germany.
- Bernstein Center for Computational Neuroscience Berlin, Berlin, Germany.
| | - Carsten Duch
- Institute of Developmental Biology and Neurobiology (iDN), Johannes Gutenberg-University Mainz, Mainz, Germany.
| |
Collapse
|
10
|
Herberholz J. The giant escape neurons of crayfish: Past discoveries and present opportunities. Front Physiol 2022; 13:1052354. [PMID: 36605900 PMCID: PMC9808059 DOI: 10.3389/fphys.2022.1052354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 12/07/2022] [Indexed: 12/24/2022] Open
Abstract
Crayfish are equipped with two prominent neural circuits that control rapid, stereotyped escape behaviors. Central to these circuits are bilateral pairs of giant neurons that transverse the nervous system and generate escape tail-flips in opposite directions away from threatening stimuli.
Collapse
|
11
|
Zocchi D, Ye ES, Hauser V, O'Connell TF, Hong EJ. Parallel encoding of CO 2 in attractive and aversive glomeruli by selective lateral signaling between olfactory afferents. Curr Biol 2022; 32:4225-4239.e7. [PMID: 36070776 PMCID: PMC9561050 DOI: 10.1016/j.cub.2022.08.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 07/13/2022] [Accepted: 08/10/2022] [Indexed: 12/14/2022]
Abstract
We describe a novel form of selective crosstalk between specific classes of primary olfactory receptor neurons (ORNs) in the Drosophila antennal lobe. Neurotransmitter release from ORNs is driven by two distinct sources of excitation: direct activity derived from the odorant receptor and stimulus-selective lateral signals originating from stereotypic subsets of other ORNs. Consequently, the level of presynaptic neurotransmitter release from an ORN can be significantly dissociated from its firing rate. Stimulus-selective lateral signaling results in the distributed representation of CO2-a behaviorally important environmental cue that directly excites a single ORN class-in multiple olfactory glomeruli, each with distinct response dynamics. CO2-sensitive glomeruli coupled to behavioral attraction respond preferentially to fast changes in CO2 concentration, whereas those coupled to behavioral aversion more closely follow absolute levels of CO2. Behavioral responses to CO2 also depend on the temporal structure of the stimulus: flies walk upwind to fluctuating, but not sustained, pulses of CO2. Stimulus-selective lateral signaling generalizes to additional odors and glomeruli, revealing a subnetwork of lateral interactions between ORNs that reshapes the spatial and temporal structure of odor representations in a stimulus-specific manner.
Collapse
Affiliation(s)
- Dhruv Zocchi
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Emily S Ye
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Virginie Hauser
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Thomas F O'Connell
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Elizabeth J Hong
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
| |
Collapse
|
12
|
Tolkin T, Mohammad A, Starich TA, Nguyen KCQ, Hall DH, Schedl T, Hubbard EJA, Greenstein D. Innexin function dictates the spatial relationship between distal somatic cells in the Caenorhabditis elegans gonad without impacting the germline stem cell pool. eLife 2022; 11:e74955. [PMID: 36098634 PMCID: PMC9473689 DOI: 10.7554/elife.74955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Accepted: 08/08/2022] [Indexed: 12/01/2022] Open
Abstract
Gap-junctional signaling mediates myriad cellular interactions in metazoans. Yet, how gap junctions control the positioning of cells in organs is not well understood. Innexins compose gap junctions in invertebrates and affect organ architecture. Here, we investigate the roles of gap-junctions in controlling distal somatic gonad architecture and its relationship to underlying germline stem cells in Caenorhabditis elegans. We show that a reduction of soma-germline gap-junctional activity causes displacement of distal sheath cells (Sh1) towards the distal end of the gonad. We confirm, by live imaging, transmission electron microscopy, and antibody staining, that bare regions-lacking somatic gonadal cell coverage of germ cells-are present between the distal tip cell (DTC) and Sh1, and we show that an innexin fusion protein used in a prior study encodes an antimorphic gap junction subunit that mispositions Sh1. We determine that, contrary to the model put forth in the prior study based on this fusion protein, Sh1 mispositioning does not markedly alter the position of the borders of the stem cell pool nor of the progenitor cell pool. Together, these results demonstrate that gap junctions can control the position of Sh1, but that Sh1 position is neither relevant for GLP-1/Notch signaling nor for the exit of germ cells from the stem cell pool.
Collapse
Affiliation(s)
- Theadora Tolkin
- Kimmel Center for Biology and Medicine at the Skirball Institute, NYU Grossman School of MedicineNew YorkUnited States
- Department of Cell Biology, NYU Grossman School of MedicineNew YorkUnited States
| | - Ariz Mohammad
- Department of Genetics, Washington University School of MedicineSt. LouisUnited States
| | - Todd A Starich
- Department of Genetics, Cell Biology and Development, University of MinnesotaMinneapolisUnited States
| | - Ken CQ Nguyen
- Department of Neuroscience, Albert Einstein College of MedicineThe BronxUnited States
| | - David H Hall
- Department of Neuroscience, Albert Einstein College of MedicineThe BronxUnited States
| | - Tim Schedl
- Department of Genetics, Washington University School of MedicineSt. LouisUnited States
| | - E Jane Albert Hubbard
- Kimmel Center for Biology and Medicine at the Skirball Institute, NYU Grossman School of MedicineNew YorkUnited States
- Department of Cell Biology, NYU Grossman School of MedicineNew YorkUnited States
- Department of Pathology, NYU Grossman School of MedicineNew YorkUnited States
| | - David Greenstein
- Department of Genetics, Cell Biology and Development, University of MinnesotaMinneapolisUnited States
| |
Collapse
|
13
|
Güiza J, García A, Arriagada J, Gutiérrez C, González J, Márquez-Miranda V, Alegría-Arcos M, Duarte Y, Rojas M, González-Nilo F, Sáez JC, Vega JL. Unnexins: Homologs of innexin proteins in Trypanosomatidae parasites. J Cell Physiol 2021; 237:1547-1560. [PMID: 34779505 DOI: 10.1002/jcp.30626] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 10/05/2021] [Accepted: 10/26/2021] [Indexed: 11/07/2022]
Abstract
Large-pore channels, including those formed by connexin, pannexin, innexin proteins, are part of a broad family of plasma membrane channels found in vertebrates and invertebrates, which share topology features. Despite their relevance in parasitic diseases such as Chagas and malaria, it was unknown whether these large-pore channels are present in unicellular organisms. We identified 14 putative proteins in Trypanosomatidae parasites as presumptive homologs of innexin proteins. All proteins possess the canonical motif of the innexin family, a pentapeptide YYQWV, and 10 of them share a classical membrane topology of large-pore channels. A sequence similarity network analysis confirmed their closeness to innexin proteins. A bioinformatic model showed that a homolog of Trypanosoma cruzi (T. cruzi) could presumptively form a stable octamer channel with a highly positive electrostatic potential in the internal cavities and extracellular entrance due to the notable predominance of residues such as Arg or Lys. In vitro dye uptake assays showed that divalent cations-free solution increases YO-PRO-1 uptake and hyperosmotic stress increases DAPI uptake in epimastigotes of T. cruzi. Those effects were sensitive to probenecid. Furthermore, probenecid reduced the proliferation and transformation of T. cruzi. Moreover, probenecid or carbenoxolone increased the parasite sensitivity to antiparasitic drugs commonly used in therapy against Chagas. Our study suggests the existence of innexin homologs in unicellular organisms, which could be protein subunits of new large-pore channels in unicellular organisms.
Collapse
Affiliation(s)
- Juan Güiza
- Laboratory of Gap Junction Proteins and Parasitic Diseases (GaPaL), Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| | - Aníbal García
- Laboratory of Gap Junction Proteins and Parasitic Diseases (GaPaL), Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| | - Javiera Arriagada
- Laboratory of Gap Junction Proteins and Parasitic Diseases (GaPaL), Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| | - Camila Gutiérrez
- Laboratory of Gap Junction Proteins and Parasitic Diseases (GaPaL), Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| | - Jorge González
- Centro de Investigación en Inmunología y Biotecnología Biomédica de Antofagasta (CIIBBA), Universidad de Antofagasta, Antofagasta, Chile.,Molecular Parasitology Unit, Medical Technology Department, Faculty of Health Sciences, Universidad de Antofagasta, Antofagasta, Chile
| | | | | | - Yorley Duarte
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Maximiliano Rojas
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Fernando González-Nilo
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile.,Instituto de Neurosciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Juan C Sáez
- Instituto de Neurosciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - José L Vega
- Laboratory of Gap Junction Proteins and Parasitic Diseases (GaPaL), Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile.,Centro de Investigación en Inmunología y Biotecnología Biomédica de Antofagasta (CIIBBA), Universidad de Antofagasta, Antofagasta, Chile
| |
Collapse
|
14
|
Neves JH, Rezende-Teixeira P, Palomino NB, Machado-Santelli GM. Molecular and morphological approach to study the innexin gap junctions in Rhynchosciara americana. Open Biol 2021; 11:210224. [PMID: 34753320 PMCID: PMC8580445 DOI: 10.1098/rsob.210224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Gap junctions mediate communication between adjacent cells and are fundamental to the development and homeostasis in multicellular organisms. In invertebrates, gap junctions are formed by transmembrane proteins called innexins. Gap junctions allow the passage of small molecules through an intercellular channel, between a cell and another adjacent cell. The dipteran Rhynchosciara americana has contributed to studying the biology of invertebrates and the study of the interaction and regulation of genes during biological development. Therefore, this paper aimed to study the R. americana innexin-2 by molecular characterization, analysis of the expression profile and cellular localization. The molecular characterization results confirm that the message is from a gap junction protein and analysis of the expression and cellular localization profile shows that innexin-2 can participate in many physiological processes during the development of R. americana.
Collapse
Affiliation(s)
- Jorge Henrique Neves
- Institute of Biomedical Sciences, University of São Paulo, Avenida Professor Lineu Prestes, 1524 – sala 307, São Paulo, SP, Brazil
| | - Paula Rezende-Teixeira
- Institute of Biomedical Sciences, University of São Paulo, Avenida Professor Lineu Prestes, 1524 – sala 307, São Paulo, SP, Brazil
| | - Natalia Bazan Palomino
- Institute of Biomedical Sciences, University of São Paulo, Avenida Professor Lineu Prestes, 1524 – sala 307, São Paulo, SP, Brazil
| | - Glaucia Maria Machado-Santelli
- Institute of Biomedical Sciences, University of São Paulo, Avenida Professor Lineu Prestes, 1524 – sala 307, São Paulo, SP, Brazil
| |
Collapse
|
15
|
Scheffer LK, Meinertzhagen IA. A connectome is not enough - what is still needed to understand the brain of Drosophila? J Exp Biol 2021; 224:272599. [PMID: 34695211 DOI: 10.1242/jeb.242740] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Understanding the structure and operation of any nervous system has been a subject of research for well over a century. A near-term opportunity in this quest is to understand the brain of a model species, the fruit fly Drosophila melanogaster. This is an enticing target given its relatively small size (roughly 200,000 neurons), coupled with the behavioral richness that this brain supports, and the wide variety of techniques now available to study both brain and behavior. It is clear that within a few years we will possess a connectome for D. melanogaster: an electron-microscopy-level description of all neurons and their chemical synaptic connections. Given what we will soon have, what we already know and the research that is currently underway, what more do we need to know to enable us to understand the fly's brain? Here, we itemize the data we will need to obtain, collate and organize in order to build an integrated model of the brain of D. melanogaster.
Collapse
Affiliation(s)
- Louis K Scheffer
- Howard Hughes Medical Institute, 19741 Smith Circle, Ashburn, VA 20147, USA
| | | |
Collapse
|
16
|
Huang YC, Chen KH, Chen YY, Tsao LH, Yeh TH, Chen YC, Wu PY, Wang TW, Yu JY. βPS-Integrin acts downstream of Innexin 2 in modulating stretched cell morphogenesis in the Drosophila ovary. G3-GENES GENOMES GENETICS 2021; 11:6310741. [PMID: 34544125 PMCID: PMC8496311 DOI: 10.1093/g3journal/jkab215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 06/14/2021] [Indexed: 11/25/2022]
Abstract
During oogenesis, a group of specialized follicle cells, known as stretched cells (StCs), flatten drastically from cuboidal to squamous shape. While morphogenesis of epithelia is critical for organogenesis, genes and signaling pathways involved in this process remain to be revealed. In addition to formation of gap junctions for intercellular exchange of small molecules, gap junction proteins form channels or act as adaptor proteins to regulate various cellular behaviors. In invertebrates, gap junction proteins are Innexins. Knockdown of Innexin 2 but not other Innexins expressed in follicle cells attenuates StC morphogenesis. Interestingly, blocking of gap junctions with an inhibitor carbenoxolone does not affect StC morphogenesis, suggesting that Innexin 2 might control StCs flattening in a gap-junction-independent manner. An excessive level of βPS-Integrin encoded by myospheroid is detected in Innexin 2 mutant cells specifically during StC morphogenesis. Simultaneous knockdown of Innexin 2 and myospheroid partially rescues the morphogenetic defect resulted from Innexin 2 knockdown. Furthermore, reduction of βPS-Integrin is sufficient to induce early StCs flattening. Taken together, our data suggest that βPS-Integrin acts downstream of Innexin 2 in modulating StCs morphogenesis.
Collapse
Affiliation(s)
- Yi-Chia Huang
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Kuan-Han Chen
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Yu-Yang Chen
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Liang-Hsuan Tsao
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Tsung-Han Yeh
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Yu-Chia Chen
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Ping-Yen Wu
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Tsu-Wei Wang
- Department of Life Science, National Taiwan Normal University, Taipei 116, Taiwan
| | - Jenn-Yah Yu
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan.,Brain Research Center, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| |
Collapse
|
17
|
García-Rodríguez C, Bravo-Tobar ID, Duarte Y, Barrio LC, Sáez JC. Contribution of non-selective membrane channels and receptors in epilepsy. Pharmacol Ther 2021; 231:107980. [PMID: 34481811 DOI: 10.1016/j.pharmthera.2021.107980] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 08/17/2021] [Accepted: 08/18/2021] [Indexed: 12/14/2022]
Abstract
Overcoming refractory epilepsy's resistance to the combination of antiepileptic drugs (AED), mitigating side effects, and preventing sudden unexpected death in epilepsy are critical goals for therapy of this disorder. Current therapeutic strategies are based primarily on neurocentric mechanisms, overlooking the participation of astrocytes and microglia in the pathophysiology of epilepsy. This review is focused on a set of non-selective membrane channels (permeable to ions and small molecules), including channels and ionotropic receptors of neurons, astrocytes, and microglia, such as: the hemichannels formed by Cx43 and Panx1; the purinergic P2X7 receptors; the transient receptor potential vanilloid (TRPV1 and TRPV4) channels; calcium homeostasis modulators (CALHMs); transient receptor potential canonical (TRPC) channels; transient receptor potential melastatin (TRPM) channels; voltage-dependent anion channels (VDACs) and volume-regulated anion channels (VRACs), which all have in common being activated by epileptic activity and the capacity to exacerbate seizure intensity. Specifically, we highlight evidence for the activation of these channels/receptors during epilepsy including neuroinflammation and oxidative stress, discuss signaling pathways and feedback mechanisms, and propose the functions of each of them in acute and chronic epilepsy. Studying the role of these non-selective membrane channels in epilepsy and identifying appropriate blockers for one or more of them could provide complementary therapies to better alleviate the disease.
Collapse
Affiliation(s)
- Claudia García-Rodríguez
- Instituto de Neurociencia, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Chile.
| | - Iván D Bravo-Tobar
- Instituto de Neurociencia, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Chile
| | - Yorley Duarte
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Luis C Barrio
- Hospital Ramon y Cajal-IRYCIS, Centro de Tecnología Biomédica de la Universidad Politécnica, Madrid, Spain
| | - Juan C Sáez
- Instituto de Neurociencia, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Chile.
| |
Collapse
|
18
|
Syrjanen J, Michalski K, Kawate T, Furukawa H. On the molecular nature of large-pore channels. J Mol Biol 2021; 433:166994. [PMID: 33865869 PMCID: PMC8409005 DOI: 10.1016/j.jmb.2021.166994] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 04/08/2021] [Accepted: 04/08/2021] [Indexed: 12/25/2022]
Abstract
Membrane transport is a fundamental means to control basic cellular processes such as apoptosis, inflammation, and neurodegeneration and is mediated by a number of transporters, pumps, and channels. Accumulating evidence over the last half century has shown that a type of so-called "large-pore channel" exists in various tissues and organs in gap-junctional and non-gap-junctional forms in order to flow not only ions but also metabolites such as ATP. They are formed by a number of protein families with little or no evolutionary linkages including connexin, innexin, pannexin, leucine-rich repeat-containing 8 (LRRC8), and calcium homeostasis modulator (CALHM). This review summarizes the history and concept of large-pore channels starting from connexin gap junction channels to the more recent developments in innexin, pannexin, LRRC8, and CALHM. We describe structural and functional features of large-pore channels that are crucial for their diverse functions on the basis of available structures.
Collapse
Affiliation(s)
- Johanna Syrjanen
- W.M. Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Kevin Michalski
- W.M. Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Toshimitsu Kawate
- Department of Molecular Medicine, Fields of Biochemistry, Molecular, and Cell Biology (BMCB), and Biophysics, Cornell University, Ithaca, NY 14853, USA
| | - Hiro Furukawa
- W.M. Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
| |
Collapse
|
19
|
Güiza J, Arriagada J, Rodríguez L, Gutiérrez C, Duarte Y, Sáez JC, Vega JL. Anti-parasitic drugs modulate the non-selective channels formed by connexins or pannexins. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166188. [PMID: 34102257 DOI: 10.1016/j.bbadis.2021.166188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 05/03/2021] [Accepted: 05/31/2021] [Indexed: 10/21/2022]
Abstract
The proteins connexins, innexins, and pannexins are the subunits of non-selective channels present in the cell membrane in vertebrates (connexins and pannexins) and invertebrates (innexins). These channels allow the transfer of ions and molecules across the cell membrane or, and in many cases, between the cytoplasm of neighboring cells. These channels participate in various physiological processes, particularly under pathophysiological conditions, such as bacterial, viral, and parasitic infections. Interestingly, some anti-parasitic drugs also block connexin- or pannexin-formed channels. Their effects on host channels permeable to molecules that favor parasitic infection can further explain the anti-parasitic effects of some of these compounds. In this review, the effects of drugs with known anti-parasitic activity that modulate non-selective channels formed by connexins or pannexins are discussed. Previous studies that have reported the presence of these proteins in worms, ectoparasites, and protozoa that cause parasitic infections have also been reviewed.
Collapse
Affiliation(s)
- Juan Güiza
- Laboratory of Gap Junction and Parasitic Diseases (GaPaL), Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| | - Javiera Arriagada
- Laboratory of Gap Junction and Parasitic Diseases (GaPaL), Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| | - Luis Rodríguez
- Laboratory of Gap Junction and Parasitic Diseases (GaPaL), Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| | - Camila Gutiérrez
- Laboratory of Gap Junction and Parasitic Diseases (GaPaL), Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| | - Yorley Duarte
- Instituto de Neurociencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile; Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Av. República 330, Santiago 8370146, Chile
| | - Juan C Sáez
- Instituto de Neurociencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - José L Vega
- Laboratory of Gap Junction and Parasitic Diseases (GaPaL), Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile.
| |
Collapse
|
20
|
Kordowitzki P, Sokołowska G, Wasielak-Politowska M, Skowronska A, Skowronski MT. Pannexins and Connexins: Their Relevance for Oocyte Developmental Competence. Int J Mol Sci 2021; 22:ijms22115918. [PMID: 34072911 PMCID: PMC8199496 DOI: 10.3390/ijms22115918] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/23/2021] [Accepted: 05/28/2021] [Indexed: 12/29/2022] Open
Abstract
The oocyte is the major determinant of embryo developmental competence in all mammalian species. Although fundamental advances have been generated in the field of reproductive medicine and assisted reproductive technologies in the past three decades, researchers and clinicians are still trying to elucidate molecular factors and pathways, which could be pivotal for the oocyte’s developmental competence. The cell-to-cell and cell-to-matrix communications are crucial not only for oocytes but also for multicellular organisms in general. This latter mentioned communication is among others possibly due to the Connexin and Pannexin families of large-pore forming channels. Pannexins belong to a protein group of ATP-release channels, therefore of high importance for the oocyte due to its requirements of high energy supply. An increasing body of studies on Pannexins provided evidence that these channels not only play a role during physiological processes of an oocyte but also during pathological circumstances which could lead to the development of diseases or infertility. Connexins are proteins that form membrane channels and gap-junctions, and more precisely, these proteins enable the exchange of some ions and molecules, and therefore they do play a fundamental role in the communication between the oocyte and accompanying cells. Herein, the role of Pannexins and Connexins for the processes of oogenesis, folliculogenesis, oocyte maturation and fertilization will be discussed and, at the end of this review, Pannexin and Connexin related pathologies and their impact on the developmental competence of oocytes will be provided.
Collapse
Affiliation(s)
- Paweł Kordowitzki
- Institute of Animal Reproduction and Food Research of Polish Academy of Sciences, Bydgoska Street 7, 10-243 Olsztyn, Poland;
- Department of Basic and Preclinical Sciences, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, Gagarina Street 7, 87-100 Torun, Poland
| | - Gabriela Sokołowska
- Department of Reproduction and Gynecological Endocrinology, Medical University of Bialystok, Jana Kilińskiego Street 1, 15-089 Białystok, Poland;
| | - Marta Wasielak-Politowska
- Center of Gynecology, Endocrinology and Reproductive Medicine—Artemida, Jagiellońska Street 78, 10-357 Olsztyn, Poland;
| | - Agnieszka Skowronska
- Department of Human Physiology and Pathophysiology, School of Medicine, Collegium Medicum, University of Warmia and Mazury, Warszawska Street 30, 10-357 Olsztyn, Poland;
| | - Mariusz T. Skowronski
- Department of Basic and Preclinical Sciences, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, Gagarina Street 7, 87-100 Torun, Poland
- Correspondence: ; Tel.: +48-566-112-231
| |
Collapse
|
21
|
Lasseigne AM, Echeverry FA, Ijaz S, Michel JC, Martin EA, Marsh AJ, Trujillo E, Marsden KC, Pereda AE, Miller AC. Electrical synaptic transmission requires a postsynaptic scaffolding protein. eLife 2021; 10:e66898. [PMID: 33908867 PMCID: PMC8081524 DOI: 10.7554/elife.66898] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 03/30/2021] [Indexed: 02/06/2023] Open
Abstract
Electrical synaptic transmission relies on neuronal gap junctions containing channels constructed by Connexins. While at chemical synapses neurotransmitter-gated ion channels are critically supported by scaffolding proteins, it is unknown if channels at electrical synapses require similar scaffold support. Here, we investigated the functional relationship between neuronal Connexins and Zonula Occludens 1 (ZO1), an intracellular scaffolding protein localized to electrical synapses. Using model electrical synapses in zebrafish Mauthner cells, we demonstrated that ZO1 is required for robust synaptic Connexin localization, but Connexins are dispensable for ZO1 localization. Disrupting this hierarchical ZO1/Connexin relationship abolishes electrical transmission and disrupts Mauthner cell-initiated escape responses. We found that ZO1 is asymmetrically localized exclusively postsynaptically at neuronal contacts where it functions to assemble intercellular channels. Thus, forming functional neuronal gap junctions requires a postsynaptic scaffolding protein. The critical function of a scaffolding molecule reveals an unanticipated complexity of molecular and functional organization at electrical synapses.
Collapse
Affiliation(s)
| | - Fabio A Echeverry
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of MedicineBronxUnited States
| | - Sundas Ijaz
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of MedicineBronxUnited States
| | | | - E Anne Martin
- Institute of Neuroscience, University of OregonEugeneUnited States
| | - Audrey J Marsh
- Institute of Neuroscience, University of OregonEugeneUnited States
| | - Elisa Trujillo
- Institute of Neuroscience, University of OregonEugeneUnited States
| | - Kurt C Marsden
- Department of Biological Sciences, NC State UniversityRaleighUnited States
| | - Alberto E Pereda
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of MedicineBronxUnited States
| | - Adam C Miller
- Institute of Neuroscience, University of OregonEugeneUnited States
| |
Collapse
|
22
|
Identification and classification of innexin gene transcripts in the central nervous system of the terrestrial slug Limax valentianus. PLoS One 2021; 16:e0244902. [PMID: 33857131 PMCID: PMC8049302 DOI: 10.1371/journal.pone.0244902] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 03/09/2021] [Indexed: 12/20/2022] Open
Abstract
Intercellular gap junction channels and single-membrane channels have been reported to regulate electrical synapse and the brain function. Innexin is known as a gap junction-related protein in invertebrates and is involved in the formation of intercellular gap junction channels and single-cell membrane channels. Multiple isoforms of innexin protein in each species enable the precise regulation of channel function. In molluscan species, sequence information of innexins is still limited and the sequences of multiple innexin isoforms have not been classified. This study examined the innexin transcripts expressed in the central nervous system of the terrestrial slug Limax valentianus and identified 16 transcripts of 12 innexin isoforms, including the splicing variants. We performed phylogenetic analysis and classified the isoforms with other molluscan innexin sequences. Next, the phosphorylation, N-glycosylation, and S-nitrosylation sites were predicted to characterize the innexin isoforms. Further, we identified 16 circular RNA sequences of nine innexin isoforms in the central nervous system of Limax. The identification and classification of molluscan innexin isoforms provided novel insights for understanding the regulatory mechanism of innexin in this phylum.
Collapse
|
23
|
Wang Q, Liu S. Analysis of Hemichannels and Gap Junctions: Application and Extension of the Passive Transmembrane Ion Transport Model. Front Cell Neurosci 2021; 15:596953. [PMID: 33897368 PMCID: PMC8058385 DOI: 10.3389/fncel.2021.596953] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 02/15/2021] [Indexed: 02/02/2023] Open
Abstract
Electrical synaptic transmission is an essential form of interneuronal communication which is mediated by gap junctions that permit ion flow. Three gene families (connexins, innexins, and pannexins) have evolved to form gap junctional channels. Each gap junctional channel is formed by the docking of the hemichannel of one cell with the corresponding hemichannel of an adjacent cell. To date, there has been a lack of study models to describe this structure in detail. In this study, we demonstrate that numerical simulations suggest that the passive transmembrane ion transport model, based on the generality of ion channels, also applies to hemichannels in non-junctional plasma membranes. On this basis, we established a gap junctional channel model, which describes hemichannels' docking. We simulated homotypic and heterotypic gap junctions formed by connexins, innexins, and pannexins. Based on the numerical results and our theoretical model, we discussed the physiology of hemichannels and gap junctions, including ion blockage of hemichannels, voltage gating of gap junctions, and asymmetry and delay of electrical synaptic transmission, for which the numerical simulations are first comprehensively realized.
Collapse
Affiliation(s)
- Qiqian Wang
- School of Mathematics, South China University of Technology, Guangzhou, China
| | - Shenquan Liu
- School of Mathematics, South China University of Technology, Guangzhou, China
| |
Collapse
|
24
|
Bhat EA, Sajjad N. Human Pannexin 1 channel: Insight in structure-function mechanism and its potential physiological roles. Mol Cell Biochem 2021; 476:1529-1540. [PMID: 33394272 DOI: 10.1007/s11010-020-04002-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 11/21/2020] [Indexed: 12/15/2022]
Abstract
Pannexins, large non-gap junction super family exists in vertebrates, play multiple roles in different cellular functions through their ATP release. Panx1-mediated adenosine 5'-triphosphate (ATP) release plays a vital role in physiological and pathophysiological conditions and is known major extracellular molecule in purinergic signaling. To modulate their function in vivo, a proper regulation of channel is necessary. Post-translational modifications are considered to be some regulating mechanisms for PANX1, while PANX2, PANX3 have been uncharacterized to date. Through their significant evidences, PANXs exclude from gap junction and conduits ATP release and other cellular molecules from cells by various mechanisms. PANX1 is most extensive characterized and implicated in ATP signaling and inflammatory processes. Despite the constant advances, much significance of PANX1 in physiological processes remains elusive. Recently, various research groups along with our group have reported the Cryo-EM structure of Panx1 channel and uncovered the hidden functions in structure-function mechanism as well as to provide the clear understanding in physiological and pathophysiological roles. These research groups reported the novel heptameric structure with contains 4 transmembrane helices (TM), two extracellular loops and one intracellular loop with N and C terminus located at the intracellular side. In addition, the structure contains a large pore of which an inhibitor CBX act as a plug that blocking the passage of substrate. In this context, this review will present current mechanistic understanding in structure and function together with significant physiological roles particularly ATP release in health and disease. As such, this review emphasizes on recent functional properties associated with novel heptameric channel and demystifies channel-mediated ATP release function.
Collapse
Affiliation(s)
- Eijaz Ahmed Bhat
- Life Science Institute, Zhejiang University, Hangzhou, 310058, Zhejiang, People's Republic of China.
| | - Nasreena Sajjad
- Department of Biochemistry, University of Kashmir, Hazratbal, Jammu and Kashmir, India
| |
Collapse
|
25
|
López X, Escamilla R, Fernández P, Duarte Y, González-Nilo F, Palacios-Prado N, Martinez AD, Sáez JC. Stretch-Induced Activation of Pannexin 1 Channels Can Be Prevented by PKA-Dependent Phosphorylation. Int J Mol Sci 2020; 21:ijms21239180. [PMID: 33276429 PMCID: PMC7731223 DOI: 10.3390/ijms21239180] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 11/19/2020] [Accepted: 11/27/2020] [Indexed: 02/07/2023] Open
Abstract
Pannexin 1 channels located in the cell membrane are permeable to ions, metabolites, and signaling molecules. While the activity of these channels is known to be modulated by phosphorylation on T198, T308, and S206, the possible involvement of other putative phosphorylation sites remains unknown. Here, we describe that the activity of Panx1 channels induced by mechanical stretch is reduced by adenosine via a PKA-dependent pathway. The mechanical stretch-induced activity-measured by changes in DAPI uptake-of Panx1 channels expressed in HeLa cell transfectants was inhibited by adenosine or cAMP analogs that permeate the cell membrane. Moreover, inhibition of PKA but not PKC, p38 MAPK, Akt, or PKG prevented the effects of cAMP analogs, suggesting the involvement of Panx1 phosphorylation by PKA. Accordingly, alanine substitution of T302 or S328, two putative PKA phosphorylation sites, prevented the inhibitory effect of cAMP analogs. Moreover, phosphomimetic mutation of either T302 or S328 to aspartate prevented the mechanical stretch-induced activation of Panx1 channels. A molecular dynamics simulation revealed that T302 and S328 are located in the water-lipid interphase near the lateral tunnel of the intracellular region, suggesting that their phosphorylation could promote conformational changes in lateral tunnels. Thus, Panx1 phosphorylation via PKA could be modulated by G protein-coupled receptors associated with the Gs subunit.
Collapse
Affiliation(s)
- Ximena López
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile;
- Facultad de Ciencias, Instituto de Neurociencias and Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso 2381850, Chile; (R.E.); (P.F.); (Y.D.); (F.G.-N.); (A.D.M.)
- Correspondence: (X.L.); (J.C.S.); Tel.: +56-2-26862862 (X.L.); +56-32-2508040 (J.C.S.)
| | - Rosalba Escamilla
- Facultad de Ciencias, Instituto de Neurociencias and Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso 2381850, Chile; (R.E.); (P.F.); (Y.D.); (F.G.-N.); (A.D.M.)
| | - Paola Fernández
- Facultad de Ciencias, Instituto de Neurociencias and Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso 2381850, Chile; (R.E.); (P.F.); (Y.D.); (F.G.-N.); (A.D.M.)
| | - Yorley Duarte
- Facultad de Ciencias, Instituto de Neurociencias and Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso 2381850, Chile; (R.E.); (P.F.); (Y.D.); (F.G.-N.); (A.D.M.)
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Av. República 330, Santiago 8370146, Chile
| | - Fernando González-Nilo
- Facultad de Ciencias, Instituto de Neurociencias and Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso 2381850, Chile; (R.E.); (P.F.); (Y.D.); (F.G.-N.); (A.D.M.)
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Av. República 330, Santiago 8370146, Chile
| | - Nicolás Palacios-Prado
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile;
- Facultad de Ciencias, Instituto de Neurociencias and Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso 2381850, Chile; (R.E.); (P.F.); (Y.D.); (F.G.-N.); (A.D.M.)
| | - Agustín D. Martinez
- Facultad de Ciencias, Instituto de Neurociencias and Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso 2381850, Chile; (R.E.); (P.F.); (Y.D.); (F.G.-N.); (A.D.M.)
| | - Juan C. Sáez
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile;
- Facultad de Ciencias, Instituto de Neurociencias and Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso 2381850, Chile; (R.E.); (P.F.); (Y.D.); (F.G.-N.); (A.D.M.)
- Correspondence: (X.L.); (J.C.S.); Tel.: +56-2-26862862 (X.L.); +56-32-2508040 (J.C.S.)
| |
Collapse
|
26
|
Meng L, Yan D. NLR-1/CASPR Anchors F-Actin to Promote Gap Junction Formation. Dev Cell 2020; 55:574-587.e3. [PMID: 33238150 DOI: 10.1016/j.devcel.2020.10.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 08/05/2020] [Accepted: 10/28/2020] [Indexed: 12/31/2022]
Abstract
Gap junctions are present in most tissues and play essential roles in various biological processes. However, we know surprisingly little about the molecular mechanisms underlying gap junction formation. Here, we uncover the essential role of a conserved EGF- and laminin-G-domain-containing protein nlr-1/CASPR in the regulation of gap junction formation in multiple tissues across different developmental stages in C. elegans. NLR-1 is located in the gap junction perinexus, a region adjacent to but not overlapping with gap junctions, and forms puncta before the clusters of gap junction channels appear on the membrane. We show that NLR-1 can directly bind to actin to recruit F-actin networks at the gap junction formation plaque, and the formation of F-actin patches plays a critical role in the assembly of gap junction channels. Our findings demonstrate that nlr-1/CASPR acts as an early stage signal for gap junction formation through anchoring of F-actin networks.
Collapse
Affiliation(s)
- Lingfeng Meng
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Dong Yan
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Neurobiology, Regeneration Next, and Duke Institute for Brain Sciences, Duke University Medical Center, Durham, NC 27710, USA.
| |
Collapse
|
27
|
Schotthöfer SK, Bohrmann J. Analysing bioelectrical phenomena in the Drosophila ovary with genetic tools: tissue-specific expression of sensors for membrane potential and intracellular pH, and RNAi-knockdown of mechanisms involved in ion exchange. BMC DEVELOPMENTAL BIOLOGY 2020; 20:15. [PMID: 32635900 PMCID: PMC7341674 DOI: 10.1186/s12861-020-00220-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 06/10/2020] [Indexed: 01/16/2023]
Abstract
Background Changes in transcellular bioelectrical patterns are known to play important roles during developmental and regenerative processes. The Drosophila follicular epithelium has proven to be an appropriate model system for studying the mechanisms by which bioelectrical signals emerge and act. Fluorescent indicator dyes in combination with various inhibitors of ion-transport mechanisms have been used to investigate the generation of membrane potentials (Vmem) and intracellular pH (pHi). Both parameters as well as their anteroposterior and dorsoventral gradients were affected by the inhibitors which, in addition, led to alterations of microfilament and microtubule patterns equivalent to those observed during follicle-cell differentiation. Results We expressed two genetically-encoded fluorescent sensors for Vmem and pHi, ArcLight and pHluorin-Moesin, in the follicular epithelium of Drosophila. By means of the respective inhibitors, we obtained comparable effects on Vmem and/or pHi as previously described for Vmem- and pHi-sensitive fluorescent dyes. In a RNAi-knockdown screen, five genes of ion-transport mechanisms and gap-junction subunits were identified exerting influence on ovary development and/or oogenesis. Loss of ovaries or small ovaries were the results of soma knockdowns of the innexins inx1 and inx3, and of the DEG/ENaC family member ripped pocket (rpk). Germline knockdown of rpk also resulted in smaller ovaries. Soma knockdown of the V-ATPase-subunit vha55 caused size-reduced ovaries with degenerating follicles from stage 10A onward. In addition, soma knockdown of the open rectifier K+channel 1 (ork1) resulted in a characteristic round-egg phenotype with altered microfilament and microtubule organisation in the follicular epithelium. Conclusions The genetic tool box of Drosophila provides means for a refined and extended analysis of bioelectrical phenomena. Tissue-specifically expressed Vmem- and pHi-sensors exhibit some practical advantages compared to fluorescent indicator dyes. Their use confirms that the ion-transport mechanisms targeted by inhibitors play important roles in the generation of bioelectrical signals. Moreover, modulation of bioelectrical signals via RNAi-knockdown of genes coding for ion-transport mechanisms and gap-junction subunits exerts influence on crucial processes during ovary development and results in cytoskeletal changes and altered follicle shape. Thus, further evidence amounts for bioelectrical regulation of developmental processes via the control of both signalling pathways and cytoskeletal organisation.
Collapse
Affiliation(s)
- Susanne Katharina Schotthöfer
- RWTH Aachen University, Institut für Biologie II, Abt. Zoologie und Humanbiologie, Worringerweg 3, 52056, Aachen, Germany
| | - Johannes Bohrmann
- RWTH Aachen University, Institut für Biologie II, Abt. Zoologie und Humanbiologie, Worringerweg 3, 52056, Aachen, Germany.
| |
Collapse
|
28
|
Structural insights into gap junction channels boosted by cryo-EM. Curr Opin Struct Biol 2020; 63:42-48. [PMID: 32339861 DOI: 10.1016/j.sbi.2020.03.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 03/15/2020] [Accepted: 03/15/2020] [Indexed: 11/23/2022]
Abstract
Regulating intercellular communication is essential for multicellular organisms. Gap junction channels are the major components mediating this function, but the molecular mechanisms underlying their opening and closing remain unclear. Single-particle cryo-electron microscopy (cryo-EM) is a powerful tool for investigating high-resolution protein structures that are difficult to crystallize, such as gap junction channels. Membrane protein structures are often determined in a detergent solubilized form, but lipid bilayers provide a near native environment for structural analysis. This review focuses on recent reports of gap junction channel structures visualized by cryo-EM. An overview of the differences observed in gap junction channel structures in the presence and absence of lipids is described, which may contribute to elucidating the regulation mechanisms of gap junction channel function.
Collapse
|
29
|
Martin EA, Lasseigne AM, Miller AC. Understanding the Molecular and Cell Biological Mechanisms of Electrical Synapse Formation. Front Neuroanat 2020; 14:12. [PMID: 32372919 PMCID: PMC7179694 DOI: 10.3389/fnana.2020.00012] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 03/09/2020] [Indexed: 12/20/2022] Open
Abstract
In this review article, we will describe the recent advances made towards understanding the molecular and cell biological mechanisms of electrical synapse formation. New evidence indicates that electrical synapses, which are gap junctions between neurons, can have complex molecular compositions including protein asymmetries across joined cells, diverse morphological arrangements, and overlooked similarities with other junctions, all of which indicate new potential roles in neurodevelopmental disease. Aquatic organisms, and in particular the vertebrate zebrafish, have proven to be excellent models for elucidating the molecular mechanisms of electrical synapse formation. Zebrafish will serve as our main exemplar throughout this review and will be compared with other model organisms. We highlight the known cell biological processes that build neuronal gap junctions and compare these with the assemblies of adherens junctions, tight junctions, non-neuronal gap junctions, and chemical synapses to explore the unknown frontiers remaining in our understanding of the critical and ubiquitous electrical synapse.
Collapse
Affiliation(s)
- E Anne Martin
- Department of Biology, Institute of Neuroscience, University of Oregon, Eugene, OR, United States
| | - Abagael M Lasseigne
- Department of Biology, Institute of Neuroscience, University of Oregon, Eugene, OR, United States
| | - Adam C Miller
- Department of Biology, Institute of Neuroscience, University of Oregon, Eugene, OR, United States
| |
Collapse
|
30
|
Wang J, Zhang L, Lian S, Qin Z, Zhu X, Dai X, Huang Z, Ke C, Zhou Z, Wei J, Liu P, Hu N, Zeng Q, Dong B, Dong Y, Kong D, Zhang Z, Liu S, Xia Y, Li Y, Zhao L, Xing Q, Huang X, Hu X, Bao Z, Wang S. Evolutionary transcriptomics of metazoan biphasic life cycle supports a single intercalation origin of metazoan larvae. Nat Ecol Evol 2020; 4:725-736. [PMID: 32203475 DOI: 10.1038/s41559-020-1138-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 02/06/2020] [Indexed: 12/16/2022]
Abstract
The transient larva-bearing biphasic life cycle is the hallmark of many metazoan phyla, but how metazoan larvae originated remains a major enigma in animal evolution. There are two hypotheses for larval origin. The 'larva-first' hypothesis suggests that the first metazoans were similar to extant larvae, with later evolution of the adult-added biphasic life cycle; the 'adult-first' hypothesis suggests that the first metazoans were adult forms, with the biphasic life cycle arising later via larval intercalation. Here, we investigate the evolutionary origin of primary larvae by conducting ontogenetic transcriptome profiling for Mollusca-the largest marine phylum characterized by a trochophore larval stage and highly variable adult forms. We reveal that trochophore larvae exhibit rapid transcriptome evolution with extraordinary incorporation of novel genes (potentially contributing to adult shell evolution), and that cell signalling/communication genes (for example, caveolin and innexin) are probably crucial for larval evolution. Transcriptome age analysis of eight metazoan species reveals the wide presence of young larval transcriptomes in both trochozoans and other major metazoan lineages, therefore arguing against the prevailing larva-first hypothesis. Our findings support an adult-first evolutionary scenario with a single metazoan larval intercalation, and suggest that the first appearance of proto-larva probably occurred after the divergence of direct-developing Ctenophora from a metazoan ancestor.
Collapse
Affiliation(s)
- Jing Wang
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Lingling Zhang
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Shanshan Lian
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Zhenkui Qin
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Xuan Zhu
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Xiaoting Dai
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Zekun Huang
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Caihuan Ke
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Zunchun Zhou
- Liaoning Key Lab of Marine Fishery Molecular Biology, Liaoning Ocean and Fisheries Science Research Institute, Dalian, China
| | - Jiankai Wei
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Pingping Liu
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Naina Hu
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Qifan Zeng
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Bo Dong
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Ying Dong
- Liaoning Key Lab of Marine Fishery Molecular Biology, Liaoning Ocean and Fisheries Science Research Institute, Dalian, China
| | - Dexu Kong
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Zhifeng Zhang
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Sinuo Liu
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Yu Xia
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Yangping Li
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Liang Zhao
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Qiang Xing
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Xiaoting Huang
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Xiaoli Hu
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China.,Laboratory for Marine Fisheries Science and Food Production Processes, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Zhenmin Bao
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China.,Laboratory for Marine Fisheries Science and Food Production Processes, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Shi Wang
- MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China. .,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China. .,The Sars-Fang Centre, Ocean University of China, Qingdao, China.
| |
Collapse
|
31
|
Christie AE, Hull JJ, Dickinson PS. In silico analyses suggest the cardiac ganglion of the lobster, Homarus americanus, contains a diverse array of putative innexin/innexin-like proteins, including both known and novel members of this protein family. INVERTEBRATE NEUROSCIENCE 2020; 20:5. [PMID: 32115669 DOI: 10.1007/s10158-020-0238-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Accepted: 01/31/2020] [Indexed: 01/16/2023]
Abstract
Gap junctions are physical channels that connect adjacent cells, permitting the flow of small molecules/ions between the cytoplasms of the coupled units. Innexin/innexin-like proteins are responsible for the formation of invertebrate gap junctions. Within the nervous system, gap junctions often function as electrical synapses, providing a means for coordinating activity among electrically coupled neurons. While some gap junctions allow the bidirectional flow of small molecules/ions between coupled cells, others permit flow in one direction only or preferentially. The complement of innexins present in a gap junction determines its specific properties. Thus, understanding innexin diversity is key for understanding the full potential of electrical coupling in a species/system. The decapod crustacean cardiac ganglion (CG), which controls cardiac muscle contractions, is a simple pattern-generating neural network with extensive electrical coupling among its circuit elements. In the lobster, Homarus americanus, prior work suggested that the adult neuronal innexin complement consists of six innexins (Homam-Inx1-4 and Homam-Inx6-7). Here, using a H. americanus CG-specific transcriptome, we explored innexin complement in this portion of the lobster nervous system. With the exception of Homam-Inx4, all of the previously described innexins appear to be expressed in the H. americanus CG. In addition, transcripts encoding seven novel putative innexins (Homam-Inx8-14) were identified, four (Homam-Inx8-11) having multiple splice variants, e.g., six for Homam-Inx8. Collectively, these data indicate that the innexin complement of the lobster nervous system in general, and the CG specifically, is likely significantly greater than previously reported, suggesting the possibility of expanded gap junction diversity and function in H. americanus.
Collapse
Affiliation(s)
- Andrew E Christie
- Békésy Laboratory of Neurobiology, Pacific Biosciences Research Center, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, 1993 East-West Road, Honolulu, HI, 96822, USA.
| | - J Joe Hull
- Pest Management and Biocontrol Research Unit, US Arid Land Agricultural Research Center, USDA Agricultural Research Services, Maricopa, AZ, 85138, USA
| | - Patsy S Dickinson
- Department of Biology, Bowdoin College, 6500 College Station, Brunswick, ME, 04011, USA
| |
Collapse
|
32
|
Burendei B, Shinozaki R, Watanabe M, Terada T, Tani K, Fujiyoshi Y, Oshima A. Cryo-EM structures of undocked innexin-6 hemichannels in phospholipids. SCIENCE ADVANCES 2020; 6:eaax3157. [PMID: 32095518 PMCID: PMC7015682 DOI: 10.1126/sciadv.aax3157] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 12/02/2019] [Indexed: 06/01/2023]
Abstract
Gap junctions form intercellular conduits with a large pore size whose closed and open states regulate communication between adjacent cells. The structural basis of the mechanism by which gap junctions close, however, remains uncertain. Here, we show the cryo-electron microscopy structures of Caenorhabditis elegans innexin-6 (INX-6) gap junction proteins in an undocked hemichannel form. In the nanodisc-reconstituted structure of the wild-type INX-6 hemichannel, flat double-layer densities obstruct the channel pore. Comparison of the hemichannel structures of a wild-type INX-6 in detergent and nanodisc-reconstituted amino-terminal deletion mutant reveals that lipid-mediated amino-terminal rearrangement and pore obstruction occur upon nanodisc reconstitution. Together with molecular dynamics simulations and electrophysiology functional assays, our results provide insight into the closure of the INX-6 hemichannel in a lipid bilayer before docking of two hemichannels.
Collapse
Affiliation(s)
- Batuujin Burendei
- Division of Biological Science, School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Ruriko Shinozaki
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Masakatsu Watanabe
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Tohru Terada
- Interfaculty Initiative in Information Studies, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kazutoshi Tani
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
- CeSPIA Inc., Ōtemachi, Chiyoda, Tokyo 100-0004, Japan
| | - Atsunori Oshima
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| |
Collapse
|
33
|
Tsukamoto S, Emmei T, Nakano S, Nishio N, Sasakura H, Mori I. The Caenorhabditis elegans INX-4/Innexin is required for the fine-tuning of temperature orientation in thermotaxis behavior. Genes Cells 2020; 25:154-164. [PMID: 31917862 PMCID: PMC7078936 DOI: 10.1111/gtc.12745] [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: 12/13/2019] [Revised: 12/27/2019] [Accepted: 12/28/2019] [Indexed: 01/10/2023]
Abstract
Innexins in invertebrates are considered to play roles similar to those of connexins and pannexins in vertebrates. However, it remains poorly understood how innexins function in biological phenomena including their function in the nervous systems. Here, we identified inx‐4, a member of the innexin family in C. elegans, by a forward screening of thermotaxis‐defective mutants. The inx‐4 mutants exhibited abnormal migration to a temperature slightly higher than the cultivation temperature, called mild thermophilic behavior. Rescue experiments revealed that INX‐4 acts in the major thermosensory neuron AFD to regulate thermotaxis behavior. INX‐4::GFP fusion protein localized exclusively along axons in AFD neurons. In addition, over‐expression of INX‐4 in AFD neurons induced a cryophilic behavior, which is opposite to inx-4 mutants. Our findings suggest that INX‐4/Innexin in AFD may fine‐tune the execution of thermotaxis behavior when moving to desired temperatures.
Collapse
Affiliation(s)
- Satomi Tsukamoto
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Taishi Emmei
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Shunji Nakano
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan.,Neuroscience Institute, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Nana Nishio
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Hiroyuki Sasakura
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Ikue Mori
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan.,Neuroscience Institute, Graduate School of Science, Nagoya University, Nagoya, Japan
| |
Collapse
|
34
|
Voelker L, Upadhyaya B, Ferkey DM, Woldemariam S, L’Etoile ND, Rabinowitch I, Bai J. INX-18 and INX-19 play distinct roles in electrical synapses that modulate aversive behavior in Caenorhabditis elegans. PLoS Genet 2019; 15:e1008341. [PMID: 31658255 PMCID: PMC6837551 DOI: 10.1371/journal.pgen.1008341] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 11/07/2019] [Accepted: 10/04/2019] [Indexed: 12/23/2022] Open
Abstract
In order to respond to changing environments and fluctuations in internal states, animals adjust their behavior through diverse neuromodulatory mechanisms. In this study we show that electrical synapses between the ASH primary quinine-detecting sensory neurons and the neighboring ASK neurons are required for modulating the aversive response to the bitter tastant quinine in C. elegans. Mutant worms that lack the electrical synapse proteins INX-18 and INX-19 become hypersensitive to dilute quinine. Cell-specific rescue experiments indicate that inx-18 operates in ASK while inx-19 is required in both ASK and ASH for proper quinine sensitivity. Imaging analyses find that INX-19 in ASK and ASH localizes to the same regions in the nerve ring, suggesting that both sides of ASK-ASH electrical synapses contain INX-19. While inx-18 and inx-19 mutant animals have a similar behavioral phenotype, several lines of evidence suggest the proteins encoded by these genes play different roles in modulating the aversive quinine response. First, INX-18 and INX-19 localize to different regions of the nerve ring, indicating that they are not present in the same synapses. Second, removing inx-18 disrupts the distribution of INX-19, while removing inx-19 does not alter INX-18 localization. Finally, by using a fluorescent cGMP reporter, we find that INX-18 and INX-19 have distinct roles in establishing cGMP levels in ASK and ASH. Together, these results demonstrate that electrical synapses containing INX-18 and INX-19 facilitate modulation of ASH nociceptive signaling. Our findings support the idea that a network of electrical synapses mediates cGMP exchange between neurons, enabling modulation of sensory responses and behavior. Animals are constantly adjusting their behavior to respond to changes in the environment or to their internal state. This behavior modulation is achieved by altering the activity of neurons and circuits through a variety of neuroplasticity mechanisms. Chemical synapses are known to impact neuroplasticity in several different ways, but the diversity of mechanisms by which electrical synapses contribute is still being investigated. Electrical synapses are specialized sites of connection between neurons where ions and small signaling molecules can pass directly from one cell to the next. By passing small molecules through electrical synapses, neurons may be able to modify the activity of their neighbors. In this study we identify two genes that contribute to electrical synapses between two sensory neurons in C. elegans. We show that these electrical synapses are crucial for proper modulation of sensory responses, as without them animals are overly responsive to an aversive stimulus. In addition to pinpointing their sites of action, we present evidence that they may be contributing to neuromodulation by facilitating passage of the small molecule cGMP between neurons. Our work provides evidence for a role of electrical synapses in regulating animal behavior.
Collapse
Affiliation(s)
- Lisa Voelker
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA, United States of America
| | - Bishal Upadhyaya
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
| | - Denise M. Ferkey
- Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY, United States of America
| | - Sarah Woldemariam
- Department of Cell and Tissue Biology, University of California, San Francisco, CA, United States of America
| | - Noelle D. L’Etoile
- Department of Cell and Tissue Biology, University of California, San Francisco, CA, United States of America
| | - Ithai Rabinowitch
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
- Department of Medical Neurobiology, Faculty of Medicine Hebrew, University of Jerusalem, Jerusalem, Israel
| | - Jihong Bai
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA, United States of America
- * E-mail:
| |
Collapse
|
35
|
Gaps and barriers: Gap junctions as a channel of communication between the soma and the germline. Semin Cell Dev Biol 2019; 97:167-171. [PMID: 31558347 DOI: 10.1016/j.semcdb.2019.09.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Revised: 08/29/2019] [Accepted: 09/04/2019] [Indexed: 12/20/2022]
Abstract
Gap junctions, expressed in most tissues of the body, allow for the cytoplasmic coupling of adjacent cells and promote tissue cooperation. Gap junctions connect also the soma and the germline in many animals, and transmit somatic signals that are crucial for germline maturation and integrity. In this review, we examine the involvement of gap junctions in the relay of information between the soma and the germline, and ask whether such communication could have consequences for the progeny. While the influence of parental experiences on descendants is of great interest, the possibility that gap junctions participate in the transmission of information across generations is largely unexplored.
Collapse
|
36
|
Rabinowitch I. What would a synthetic connectome look like? Phys Life Rev 2019; 33:1-15. [PMID: 31296448 DOI: 10.1016/j.plrev.2019.06.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 06/25/2019] [Indexed: 02/07/2023]
Abstract
A major challenge of contemporary neuroscience is to unravel the structure of the connectome, the ensemble of neural connections that link between different functional units of the brain, and to reveal how this structure relates to brain function. This thriving area of research largely follows the general tradition in biology of reverse-engineering, which consists of first observing and characterizing a biological system or process, and then deconstructing it into its fundamental building blocks in order to infer its modes of operation. However, a complementary form of biology has emerged, synthetic biology, which emphasizes construction-based forward-engineering. The synthetic biology approach comprises the assembly of new biological systems out of elementary biological parts. The rationale is that the act of building a system can be a powerful method for gaining deep understanding of how that system works. As the fields of connectomics and synthetic biology are independently growing, I propose to consider the benefits of combining the two, to create synthetic connectomics, a new form of neuroscience and a new form of synthetic biology. The goal of synthetic connectomics would be to artificially design and construct the connectomes of live behaving organisms. Synthetic connectomics could serve as a unifying platform for unraveling the complexities of brain operation and perhaps also for generating new forms of artificial life, and, in general, could provide a valuable opportunity for empirically exploring theoretical predictions about network function. What would a synthetic connectome look like? What purposes would it serve? How could it be constructed? This review delineates the novel notion of a synthetic connectome and aims to lay out the initial steps towards its implementation, contemplating its impact on science and society.
Collapse
Affiliation(s)
- Ithai Rabinowitch
- Department of Medical Neurobiology, IMRIC - Institute for Medical Research Israel-Canada, Faculty of Medicine, Hebrew University of Jerusalem, Ein Kerem Campus, Jerusalem, 9112002, Israel.
| |
Collapse
|
37
|
Alcamí P, Pereda AE. Beyond plasticity: the dynamic impact of electrical synapses on neural circuits. Nat Rev Neurosci 2019; 20:253-271. [DOI: 10.1038/s41583-019-0133-5] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
|
38
|
Gourdie RG. The Cardiac Gap Junction has Discrete Functions in Electrotonic and Ephaptic Coupling. Anat Rec (Hoboken) 2018; 302:93-100. [PMID: 30565418 DOI: 10.1002/ar.24036] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 07/10/2018] [Accepted: 07/17/2018] [Indexed: 12/31/2022]
Abstract
Connexin43-formed gap junctions have long been thought to contribute to cardiac conduction in the mammalian ventricle by providing direct electrotonic connectivity between the cytoplasms of neighboring cardiomyocytes. However, accumulating data from studies of non-mammalian hearts, Connexin 43 (Cx43) knockout mice and human Cx43 mutations have raised questions as to whether gap junctions are the sole means by which electrical coupling between cardiomyocytes is accomplished. Computational and experimental work over the last decade have indicated that intercellular propagation of action potentials in the heart may involve both electrotonic and ephaptic contributions-in what has been dubbed "mixed-mode" conduction. Interestingly, the Cx43 gap junction may provide a common structural platform in mammals that facilitates the operation of these two mechanisms. In addition to gap junction channels functioning in an electrotonic role, the perinexus region at the edge of gap junctions may be provide a niche for voltage-gated sodium channels from neighboring cells to be in sufficiently close proximity to enable ephaptic transmission of action potential. A novel role has recently been identified in this potential ephaptic mechanism for inter-membrane adhesion mediated by the beta subunit (beta1/Scn1b) of the sodium channel. The new perspective of the operational redundancy that is built into cardiac electrical connectivity could provide new understanding of arrhythmia mechanisms and holds the promise for new approach to anti-arrhythmic therapy. Anat Rec, 302:93-100, 2019. © 2018 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Robert G Gourdie
- Center for Heart and Regenerative Medicine, Virginia Tech Carilion Research Institute, Virginia Tech, Roanoke, Virginia, 24016.,Department of Emergency Medicine, Virginia Tech Carilion School of Medicine, Virginia Tech, Roanoke, Virginia, 24016.,Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia, 24061
| |
Collapse
|
39
|
Reichard A, Asosingh K. Best Practices for Preparing a Single Cell Suspension from Solid Tissues for Flow Cytometry. Cytometry A 2018; 95:219-226. [PMID: 30523671 DOI: 10.1002/cyto.a.23690] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 09/26/2018] [Accepted: 11/02/2018] [Indexed: 01/02/2023]
Abstract
Preparing a single cell suspension is a critical step in any solid tissue flow cytometry experiment. Tissue dissection, enzymatic digestion, and mechanical dissociation are three significant steps leading to the degradation of the extracellular matrix and the isolation of single cells, allowing the generation of high-quality flow cytometry data. Cells and the extracellular matrix contain various proteins and other structures which must be considered when designing a tissue digestion protocol to preserve the viability of cells and the presence of relevant antigens while digesting matrix components and cleaving cell-cell junctions. Evaluation of the single cell suspension is essential before proceeding with the labeling of the cells as high viability and absence of cell debris and aggregates are critical for flow cytometry. The information presented should be used as a general guide of steps to consider when preparing a single cell suspension from solid tissues for flow cytometry experiments. © 2018 International Society for Advancement of Cytometry.
Collapse
Affiliation(s)
- Andrew Reichard
- Department of Inflammation and Immunity, Lerner Research Institute, The Cleveland Clinic, Cleveland, Ohio
| | - Kewal Asosingh
- Department of Inflammation and Immunity, Lerner Research Institute, The Cleveland Clinic, Cleveland, Ohio.,Flow Cytometry Core, Lerner Research Institute, The Cleveland Clinic, Cleveland, Ohio
| |
Collapse
|
40
|
Faber DS, Pereda AE. Two Forms of Electrical Transmission Between Neurons. Front Mol Neurosci 2018; 11:427. [PMID: 30534051 PMCID: PMC6276723 DOI: 10.3389/fnmol.2018.00427] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 11/05/2018] [Indexed: 12/30/2022] Open
Abstract
Electrical signaling is a cardinal feature of the nervous system and endows it with the capability of quickly reacting to changes in the environment. Although synaptic communication between nerve cells is perceived to be mainly chemically mediated, electrical synaptic interactions also occur. Two different strategies are responsible for electrical communication between neurons. One is the consequence of low resistance intercellular pathways, called "gap junctions", for the spread of electrical currents between the interior of two cells. The second occurs in the absence of cell-to-cell contacts and is a consequence of the extracellular electrical fields generated by the electrical activity of neurons. Here, we place present notions about electrical transmission in a historical perspective and contrast the contributions of the two different forms of electrical communication to brain function.
Collapse
Affiliation(s)
- Donald S. Faber
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States
- Marine Biological Laboratory, Woods Hole, MA, United States
| | - Alberto E. Pereda
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States
- Marine Biological Laboratory, Woods Hole, MA, United States
| |
Collapse
|
41
|
Kennedy T, Broadie K. Newly Identified Electrically Coupled Neurons Support Development of the Drosophila Giant Fiber Model Circuit. eNeuro 2018; 5:ENEURO.0346-18.2018. [PMID: 30627638 PMCID: PMC6325540 DOI: 10.1523/eneuro.0346-18.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/29/2018] [Accepted: 11/12/2018] [Indexed: 12/31/2022] Open
Abstract
The Drosophila giant fiber (GF) escape circuit is an extensively studied model for neuron connectivity and function. Researchers have long taken advantage of the simple linear neuronal pathway, which begins at peripheral sensory modalities, travels through the central GF interneuron (GFI) to motor neurons, and terminates on wing/leg muscles. This circuit is more complex than it seems, however, as there exists a complex web of coupled neurons connected to the GFI that widely innervates the thoracic ganglion. Here, we define four new neuron clusters dye coupled to the central GFI, which we name GF coupled (GFC) 1-4. We identify new transgenic Gal4 drivers that express specifically in these neurons, and map both neuronal architecture and synaptic polarity. GFC1-4 share a central site of GFI connectivity, the inframedial bridge, where the neurons each form electrical synapses. Targeted apoptotic ablation of GFC1 reveals a key role for the proper development of the GF circuit, including the maintenance of GFI connectivity with upstream and downstream synaptic partners. GFC1 ablation frequently results in the loss of one GFI, which is always compensated for by contralateral innervation from a branch of the persisting GFI axon. Overall, this work reveals extensively coupled interconnectivity within the GF circuit, and the requirement of coupled neurons for circuit development. Identification of this large population of electrically coupled neurons in this classic model, and the ability to genetically manipulate these electrically synapsed neurons, expands the GF system capabilities for the nuanced, sophisticated circuit dissection necessary for deeper investigations into brain formation.
Collapse
Affiliation(s)
- Tyler Kennedy
- Department of Biological Sciences, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
| | - Kendal Broadie
- Department of Biological Sciences, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
- Department of Cell and Developmental Biology, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
- Vanderbilt Brain Institute, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
| |
Collapse
|
42
|
Güiza J, Barría I, Sáez JC, Vega JL. Innexins: Expression, Regulation, and Functions. Front Physiol 2018; 9:1414. [PMID: 30364195 PMCID: PMC6193117 DOI: 10.3389/fphys.2018.01414] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 09/18/2018] [Indexed: 01/02/2023] Open
Abstract
The innexin (Inx) proteins form gap junction channels and non-junctional channels (named hemichannels) in invertebrates. These channels participate in cellular communication playing a relevant role in several physiological processes. Pioneer studies conducted mainly in worms and flies have shown that innexins participate in embryo development and behavior. However, recent studies have elucidated new functions of innexins in Arthropoda, Nematoda, Annelida, and Cnidaria, such as immune response, and apoptosis. This review describes emerging data of possible new roles of innexins and summarizes the data available to date.
Collapse
Affiliation(s)
- Juan Güiza
- Laboratorio de Fisiología Experimental, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| | - Iván Barría
- Laboratorio de Fisiología Experimental, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| | - Juan C Sáez
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago, Chile.,Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - José L Vega
- Laboratorio de Fisiología Experimental, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| |
Collapse
|
43
|
Welzel G, Schuster S. Long-term potentiation in an innexin-based electrical synapse. Sci Rep 2018; 8:12579. [PMID: 30135467 PMCID: PMC6105662 DOI: 10.1038/s41598-018-30966-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 08/09/2018] [Indexed: 11/08/2022] Open
Abstract
Electrical synapses are formed by two unrelated gap junction protein families, the primordial innexins (invertebrates) or the connexins (vertebrates). Although molecularly different, innexin- and connexin-based electrical synapses are strikingly similar in their membrane topology. However, it remains unclear if this similarity extends also to more sophisticated functions such as long-term potentiation which is only known in connexin-based synapses. Here we show that this capacity is not unique to connexin-based synapses. Using a method that allowed us to quantitatively measure gap-junction conductance we provide the first and unequivocal evidence of long-term potentiation in an innexin-based electrical synapse. Our findings suggest that long-term potentiation is a property that has likely existed already in ancestral gap junctions. They therefore could provide a highly potent system to dissect shared molecular mechanisms of electrical synapse plasticity.
Collapse
Affiliation(s)
- Georg Welzel
- Department of Animal Physiology, University of Bayreuth, 95440, Bayreuth, Germany.
| | - Stefan Schuster
- Department of Animal Physiology, University of Bayreuth, 95440, Bayreuth, Germany.
| |
Collapse
|
44
|
Birkholz TR, Van Huizen AV, Beane WS. Staying in shape: Planarians as a model for understanding regenerative morphology. Semin Cell Dev Biol 2018; 87:105-115. [PMID: 29738883 DOI: 10.1016/j.semcdb.2018.04.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 04/23/2018] [Accepted: 04/30/2018] [Indexed: 01/18/2023]
Abstract
A key requirement of tissue/organ regeneration is the ability to induce appropriate shape in situ. Regenerated structures need to be integrated with pre-existing ones, through the combined regulation of new tissue growth and the scaling of surrounding tissues. This requires a tightly coordinated control of individual cell functions such as proliferation and stem cell differentiation. While great strides have been made in elucidating cell growth and differentiation mechanisms, how overall shape is generated during regeneration remains unknown. This is because a significant gap remains in our understanding of how cell behaviors are coordinated at the level of tissues and organs. The highly regenerative planarian flatworm has emerged as an important model for defining and understanding regenerative shape mechanisms. This review provides an overview of the main processes known to regulate tissue and animal shape during planarian regeneration: adult stem cell regulation, the reestablishment of body axes, tissue remodeling in pre-existing structures, organ scaling and the maintenance of body proportion, and the bioelectrical regulation of animal morphology. In order for the field to move forward, it will be necessary to identify shape mutants as a means to uncover the molecular mechanisms that synchronize all these separate processes to produce the worm's final regenerative shape. This knowledge will also aid efforts to define the mechanisms that control the termination of regenerative processes.
Collapse
Affiliation(s)
- Taylor R Birkholz
- Department of Biological Sciences, Western Michigan University, 1903 W. Michigan Avenue, Kalamazoo, MI, 49008, USA
| | - Alanna V Van Huizen
- Department of Biological Sciences, Western Michigan University, 1903 W. Michigan Avenue, Kalamazoo, MI, 49008, USA
| | - Wendy S Beane
- Department of Biological Sciences, Western Michigan University, 1903 W. Michigan Avenue, Kalamazoo, MI, 49008, USA.
| |
Collapse
|
45
|
Yamada T, Strange K. Intracellular and extracellular loops of LRRC8 are essential for volume-regulated anion channel function. J Gen Physiol 2018; 150:1003-1015. [PMID: 29853476 PMCID: PMC6028502 DOI: 10.1085/jgp.201812016] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 04/02/2018] [Accepted: 05/01/2018] [Indexed: 12/13/2022] Open
Abstract
The volume-regulated anion channel (VRAC) is expressed ubiquitously in vertebrate cells and mediates swelling-induced release of Cl- and organic solutes. Recent studies by several laboratories have demonstrated conclusively that VRAC is encoded by members of the leucine-rich repeat containing 8 (Lrrc8) gene family, which comprises five members, termed Lrrc8a-e. Numerous observations indicate that VRAC is a heteromeric channel comprising the essential subunit LRRC8A and one or more of the other LRRC8 paralogs. Here we demonstrate that the intracellular loop (IL) connecting transmembrane domains 2 and 3 of LRRC8A and the first extracellular loop (EL1) connecting transmembrane domains 1 and 2 of LRRC8C, LRRC8D, or LRRC8E are both essential for VRAC activity. We generate homomeric VRACs by replacing EL1 of LRRC8A with that of LRRC8C and demonstrate normal regulation by cell swelling and shrinkage. We also observe normal volume-dependent regulation in VRAC homomers in which the IL of LRRC8C, LRRC8D, or LRRC8E is replaced with the LRRC8A IL. A 25-amino acid sequence unique to the LRRC8A IL is sufficient to generate homomeric VRAC activity when inserted into the corresponding region of LRRC8C and LRRC8E. LRRC8 chimeras containing these partial LRRC8A IL sequences exhibit altered anion permeability, rectification, and voltage sensitivity, suggesting that the LRRC8A IL plays a role in VRAC pore structure and function. Our studies provide important new insights into the structure/function roles of the LRRC8 EL1 and IL. Homomeric LRRC8 channels will simplify future studies aimed at understanding channel structure and the longstanding and vexing problem of how VRAC is regulated by cell volume changes.
Collapse
|
46
|
Li S, Bjelobaba I, Stojilkovic SS. Interactions of Pannexin1 channels with purinergic and NMDA receptor channels. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2018; 1860:166-173. [PMID: 28389204 PMCID: PMC5628093 DOI: 10.1016/j.bbamem.2017.03.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 03/28/2017] [Accepted: 03/29/2017] [Indexed: 12/31/2022]
Abstract
Pannexins are a three-member family of vertebrate plasma membrane spanning molecules that have homology to the invertebrate gap junction forming proteins, the innexins. However, pannexins do not form gap junctions but operate as plasma membrane channels. The best-characterized member of these proteins, Pannexin1 (Panx1) was suggested to be functionally associated with purinergic P2X and N-methyl-D-aspartate (NMDA) receptor channels. Activation of these receptor channels by their endogenous ligands leads to cross-activation of Panx1 channels. This in turn potentiates P2X and NMDA receptor channel signaling. Two potentiation concepts have been suggested: enhancement of the current responses and/or sustained receptor channel activation by ATP released through Panx1 pore and adenosine generated by ectonucleotidase-dependent dephosphorylation of ATP. Here we summarize the current knowledge and hypotheses about interactions of Panx1 channels with P2X and NMDA receptor channels. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
Collapse
Affiliation(s)
- Shuo Li
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, Tianjin 300387, China
| | - Ivana Bjelobaba
- Institute for Biological Research "Sinisa Stankovic", University of Belgrade, 11000 Belgrade, Serbia
| | - Stanko S Stojilkovic
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20892, USA.
| |
Collapse
|
47
|
Kolosov D, Piermarini PM, O'Donnell MJ. Malpighian tubules of Trichoplusia ni: recycling ions via gap junctions and switching between secretion and reabsorption of Na+ and K+ in the distal ileac plexus. J Exp Biol 2018; 221:jeb.172296. [DOI: 10.1242/jeb.172296] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 01/10/2018] [Indexed: 12/12/2022]
Abstract
The functional kidney in insects consists of the Malpighian tubules and hindgut. Malpighian tubules secrete ions and fluid aiding in hydromineral homeostasis, acid-base balance, and metabolic waste excretion. In many insects, including lepidopterans, the Malpighian tubule epithelium consists of principal cells (PCs) and secondary cells (SCs). The SCs in the Malpighian tubules of larvae of the lepidopteran Trichoplusia ni have been shown to reabsorb K+, transporting it in a direction opposite to that in the neighbouring PCs that secrete K+. One of the mechanisms that could enable such an arrangement is a gap junction (GJ)-based coupling of the two cell types. In the current study, we have immunolocalised GJ protein Innexin-2 to the PC-PC and SC-PC cell-cell borders. We have demonstrated that GJs in the SC-containing region of the Malpighian tubules enable Na+ and K+ reabsorption by the SCs. We also demonstrated that in ion-loaded animals PCs switch from Na+/K+ secretion to reabsorption, resulting in an ion-transporting phenotype similar to that of tubules with pharmacologically blocked GJs. Concomitantly, mRNA abundance encoding GJ proteins was downregulated. Finally, we observed that such PC-based reabsorption was only present in the distal ileac plexus connected to the rectal complex. We propose that this plasticity in the PC function in the distal ileac plexus is likely to be aimed at providing ion supply for the SC function in this segment of the tubule.
Collapse
Affiliation(s)
- Dennis Kolosov
- McMaster University, Department of Biology, Hamilton, ON, Canada
| | - Peter M. Piermarini
- The Ohio State University, Ohio Agricultural Research and Development Center, Department of Entomology, Wooster, OH, USA
| | | |
Collapse
|
48
|
Pereda AE, Macagno E. Electrical transmission: Two structures, same functions? Dev Neurobiol 2017; 77:517-521. [PMID: 28188695 DOI: 10.1002/dneu.22488] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 02/07/2017] [Indexed: 11/11/2022]
Abstract
Electrical synapses are finding increasing representation and importance in our understanding of signaling in the nervous system. In contrast to chemical synapses, at which molecules are evolutionary conserved, vertebrate and invertebrate electrical synapses represent molecularly different structures that share a common communicating strategy that allows them to serve very similar functions. A better understanding of differences and commonalities regarding the structure, function and regulation of vertebrate and invertebrate electrical synapses will lead to a better understanding of the properties and functional diversity of this modality of synaptic communication. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 517-521, 2017.
Collapse
Affiliation(s)
- Alberto E Pereda
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
| | - Eduardo Macagno
- Division of Biological Sciences, University of California San Diego, La Jolla, California
| |
Collapse
|
49
|
Otopalik AG, Lane B, Schulz DJ, Marder E. Innexin expression in electrically coupled motor circuits. Neurosci Lett 2017; 695:19-24. [PMID: 28711343 PMCID: PMC5767152 DOI: 10.1016/j.neulet.2017.07.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 06/22/2017] [Accepted: 07/11/2017] [Indexed: 12/21/2022]
Abstract
The many roles of innexins, the molecules that form gap junctions in invertebrates, have been explored in numerous species. Here, we present a summary of innexin expression and function in two small, central pattern generating circuits found in crustaceans: the stomatogastric ganglion and the cardiac ganglion. The two ganglia express multiple innexin genes, exhibit varying combinations of symmetrical and rectifying gap junctions, as well as gap junctions within and across different cell types. Past studies have revealed correlations in ion channel and innexin expression in coupled neurons, as well as intriguing functional relationships between ion channel conductances and electrical coupling. Together, these studies suggest a putative role for innexins in correlating activity between coupled neurons at the levels of gene expression and physiological activity during development and in the adult animal.
Collapse
Affiliation(s)
- Adriane G Otopalik
- Volen Center and Biology Department, Brandeis University, Waltham, MA 02454, USA.
| | - Brian Lane
- Division of Biological Sciences, University of Missouri-Columbia, Columbia, MO, 65211, USA
| | - David J Schulz
- Division of Biological Sciences, University of Missouri-Columbia, Columbia, MO, 65211, USA
| | - Eve Marder
- Volen Center and Biology Department, Brandeis University, Waltham, MA 02454, USA
| |
Collapse
|
50
|
Beyer EC, Berthoud VM. Gap junction gene and protein families: Connexins, innexins, and pannexins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:5-8. [PMID: 28559187 DOI: 10.1016/j.bbamem.2017.05.016] [Citation(s) in RCA: 130] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 05/18/2017] [Accepted: 05/25/2017] [Indexed: 02/08/2023]
Abstract
Gap junction channels facilitate the intercellular exchange of ions and small molecules. While this process is critical to all multicellular organisms, the proteins that form gap junction channels are not conserved. Vertebrate gap junctions are formed by connexins, while invertebrate gap junctions are formed by innexins. Interestingly, vertebrates and lower chordates contain innexin homologs, the pannexins, which also form channels, but rarely (if ever) make intercellular channels. While the connexin and the innexin/pannexin polypeptides do not share significant sequence similarity, all three of these protein families share a similar membrane topology and some similarities in quaternary structure. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
Collapse
Affiliation(s)
- Eric C Beyer
- Department of Pediatrics, University of Chicago, Chicago, IL 60637, United States.
| | - Viviana M Berthoud
- Department of Pediatrics, University of Chicago, Chicago, IL 60637, United States
| |
Collapse
|