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Li S, Ling R, Wu X, Liu L, Zhang H, Xuan L. The role of multiple C2 domain and transmembrane region proteins in mediating tomato development. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2025; 356:112511. [PMID: 40216259 DOI: 10.1016/j.plantsci.2025.112511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2024] [Revised: 04/06/2025] [Accepted: 04/08/2025] [Indexed: 04/14/2025]
Abstract
Multiple C2 domain and transmembrane region proteins (MCTPs) are an evolutionarily conserved family involved in protein trafficking and signal transduction. Although several investigations have demonstrated that MCTPs play crucial roles in plant growth and development, their specific biological functions within tomatoes (Solanum lycopersicum L.) remain predominantly mysterious. In this study, we identify and characterize 14 SlMCTP genes derived from tomatoes. Chromosome mapping, gene structure, phylogenetic connections, and subcellular localization are presented herein. Meanwhile, the varied expression patterns of SlMCTPs within different tissues and under diverse hormonal and NaCl treatment conditions are revealed. Moreover, we find that SlMCTP10, SlMCTP11, and SlMCTP12, which belong to the same clade, display high expression levels at the main stem apex, suggesting their potential functions in shoot development. Furthermore, we knock out the SlMCTP10 gene in tomato using CRISPR-Cas9. The Slmctp10 seedlings exhibit defects in shoot meristem development, manifested by abnormal cotyledons and shorter internodes. Together, our findings offer fundamental insights into the SlMCTP family and uncover the role of SlMCTP proteins in regulating shoot meristem development in tomato plants.
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Affiliation(s)
- Siyi Li
- College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China; Shanghai Key Laboratory of Protected Horticultural Technology, Horticulture Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai 201403, China
| | - Ribin Ling
- Shanghai Collaborative Innovation Center of Agri-Seeds/Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xuexia Wu
- Shanghai Key Laboratory of Protected Horticultural Technology, Horticulture Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai 201403, China
| | - Lu Liu
- Shanghai Collaborative Innovation Center of Agri-Seeds/Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Hui Zhang
- Shanghai Key Laboratory of Protected Horticultural Technology, Horticulture Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai 201403, China.
| | - Lijie Xuan
- Shanghai Collaborative Innovation Center of Agri-Seeds/Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China.
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2
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Wang T, Frank CA. Using Electrophysiology to Study Homeostatic Plasticity at the Drosophila Neuromuscular Junction. Cold Spring Harb Protoc 2025; 2025:pdb.top108393. [PMID: 38688539 PMCID: PMC11522024 DOI: 10.1101/pdb.top108393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
The Drosophila melanogaster neuromuscular junction (NMJ) is a superb system for studying synapse function. Beyond that, the NMJ is also great for studying forms of synaptic plasticity. Over the last 25 years, Drosophila NMJ neuroscientists have pioneered understanding of a form of plasticity called homeostatic synaptic plasticity, which imparts functional stability on synaptic connections. The reason is straightforward: The NMJ has a robust capacity for stability. Moreover, many strategies that the NMJ uses to maintain appropriate levels of function are mirrored at other metazoan synapses. Here, we introduce core approaches that neurophysiologists use to study homeostatic synaptic plasticity at the peripheral Drosophila NMJ. We focus on methods to study a specific form of homeostatic plasticity termed presynaptic homeostatic potentiation (PHP), which is the most well-characterized one. Other forms such as presynaptic homeostatic depression and developmental forms of homeostasis are briefly discussed. Finally, we share lists of several dozen factors and conditions known to influence the execution of PHP.
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Affiliation(s)
- Tingting Wang
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, D.C. 20007, USA
| | - C Andrew Frank
- Department of Anatomy and Cell Biology, Iowa Neuroscience Institute, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, USA
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3
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Liu YN, Chen WY, Yeh HL, Chen WH, Jiang KC, Li HR, Dung PVT, Chen ZQ, Lee WJ, Hsiao M, Huang J, Wen YC. MCTP1 increases the malignancy of androgen-deprived prostate cancer cells by inducing neuroendocrine differentiation and EMT. Sci Signal 2024; 17:eadc9142. [PMID: 38861615 DOI: 10.1126/scisignal.adc9142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 05/23/2024] [Indexed: 06/13/2024]
Abstract
Neuroendocrine prostate cancer (PCa) (NEPC), an aggressive subtype that is associated with poor prognosis, may arise after androgen deprivation therapy (ADT). We investigated the molecular mechanisms by which ADT induces neuroendocrine differentiation in advanced PCa. We found that transmembrane protein 1 (MCTP1), which has putative Ca2+ sensing function and multiple Ca2+-binding C2 domains, was abundant in samples from patients with advanced PCa. MCTP1 was associated with the expression of the EMT-associated transcription factors ZBTB46, FOXA2, and HIF1A. The increased abundance of MCTP1 promoted PC3 prostate cancer cell migration and neuroendocrine differentiation and was associated with SNAI1-dependent EMT in C4-2 PCa cells after ADT. ZBTB46 interacted with FOXA2 and HIF1A and increased the abundance of MCTP1 in a hypoxia-dependent manner. MCTP1 stimulated Ca2+ signaling and AKT activation to promote EMT and neuroendocrine differentiation by increasing the SNAI1-dependent expression of EMT and neuroendocrine markers, effects that were blocked by knockdown of MCTP1. These data suggest an oncogenic role for MCTP1 in the maintenance of a rare and aggressive prostate cancer subtype through its response to Ca2+ and suggest its potential as a therapeutic target.
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Affiliation(s)
- Yen-Nien Liu
- Graduate Institute of Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei 11031, Taiwan
| | - Wei-Yu Chen
- Department of Pathology, Wan Fang Hospital, Taipei Medical University, Taipei 11031, Taiwan
- Department of Pathology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan
| | - Hsiu-Lien Yeh
- Graduate Institute of Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei 11031, Taiwan
| | - Wei-Hao Chen
- Graduate Institute of Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei 11031, Taiwan
| | - Kuo-Ching Jiang
- Graduate Institute of Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei 11031, Taiwan
| | - Han-Ru Li
- Graduate Institute of Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei 11031, Taiwan
| | - Phan Vu Thuy Dung
- Graduate Institute of Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei 11031, Taiwan
| | - Zi-Qing Chen
- Division of Clinical Pharmacy, School of Pharmacy, Taipei Medical University, Taipei 11031, Taiwan
| | - Wei-Jiunn Lee
- Department of Urology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan
- Department of Medical Education and Research, Wan Fang Hospital, Taipei Medical University, Taipei 11696, Taiwan
- Cancer Center, Wan Fang Hospital, Taipei Medical University, Taipei 11696, Taiwan
| | - Michael Hsiao
- Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Jiaoti Huang
- Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA
| | - Yu-Ching Wen
- Department of Urology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan
- Department of Urology, Wan Fang Hospital, Taipei Medical University, Taipei 11031, Taiwan
- TMU Research Center of Urology and Kidney, Taipei Medical University, Taipei 11031, Taiwan
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4
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Sun Y, Men W, Kennerknecht I, Fang W, Zheng HF, Zhang W, Rao Y. Human genetics of face recognition: discovery of MCTP2 mutations in humans with face blindness (congenital prosopagnosia). Genetics 2024; 227:iyae047. [PMID: 38547502 DOI: 10.1093/genetics/iyae047] [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: 12/24/2023] [Accepted: 03/19/2024] [Indexed: 06/06/2024] Open
Abstract
Face recognition is important for both visual and social cognition. While prosopagnosia or face blindness has been known for seven decades and face-specific neurons for half a century, the molecular genetic mechanism is not clear. Here we report results after 17 years of research with classic genetics and modern genomics. From a large family with 18 congenital prosopagnosia (CP) members with obvious difficulties in face recognition in daily life, we uncovered a fully cosegregating private mutation in the MCTP2 gene which encodes a calcium binding transmembrane protein expressed in the brain. After screening through cohorts of 6589, we found more CPs and their families, allowing detection of more CP associated mutations in MCTP2. Face recognition differences were detected between 14 carriers with the frameshift mutation S80fs in MCTP2 and 19 noncarrying volunteers. Six families including one with 10 members showed the S80fs-CP correlation. Functional magnetic resonance imaging found association of impaired recognition of individual faces by MCTP2 mutant CPs with reduced repetition suppression to repeated facial identities in the right fusiform face area. Our results have revealed genetic predisposition of MCTP2 mutations in CP, 76 years after the initial report of prosopagnosia and 47 years after the report of the first CP. This is the first time a gene required for a higher form of visual social cognition was found in humans.
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Affiliation(s)
- Yun Sun
- Chinese Institutes for Medical Research, Capital Medical University, Beijing 100069, China
- Chinese Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, School of Life Sciences, Peking University, Beijing 100871, China
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen 518107, China
| | - Weiwei Men
- Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Beijing Key Lab for Medical Physics and Engineering, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871, China
| | - Ingo Kennerknecht
- Institute of Human Genetics, Westfälische Wilhelms-Universität, Münster 48149, Germany
| | - Wan Fang
- Chinese Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - Hou-Feng Zheng
- School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China
| | - Wenxia Zhang
- Chinese Institutes for Medical Research, Capital Medical University, Beijing 100069, China
- Chinese Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - Yi Rao
- Chinese Institutes for Medical Research, Capital Medical University, Beijing 100069, China
- Chinese Institute for Brain Research, Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, School of Life Sciences, Peking University, Beijing 100871, China
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen 518107, China
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5
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He K, Han Y, Li X, Hernandez RX, Riboul DV, Feghhi T, Justs KA, Mahneva O, Perry S, Macleod GT, Dickman D. Physiologic and Nanoscale Distinctions Define Glutamatergic Synapses in Tonic vs Phasic Neurons. J Neurosci 2023; 43:4598-4611. [PMID: 37221096 PMCID: PMC10286941 DOI: 10.1523/jneurosci.0046-23.2023] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 05/05/2023] [Accepted: 05/11/2023] [Indexed: 05/25/2023] Open
Abstract
Neurons exhibit a striking degree of functional diversity, each one tuned to the needs of the circuitry in which it is embedded. A fundamental functional dichotomy occurs in activity patterns, with some neurons firing at a relatively constant "tonic" rate, while others fire in bursts, a "phasic" pattern. Synapses formed by tonic versus phasic neurons are also functionally differentiated, yet the bases of their distinctive properties remain enigmatic. A major challenge toward illuminating the synaptic differences between tonic and phasic neurons is the difficulty in isolating their physiological properties. At the Drosophila neuromuscular junction, most muscle fibers are coinnervated by two motor neurons: the tonic "MN-Ib" and phasic "MN-Is." Here, we used selective expression of a newly developed botulinum neurotoxin transgene to silence tonic or phasic motor neurons in Drosophila larvae of either sex. This approach highlighted major differences in their neurotransmitter release properties, including probability, short-term plasticity, and vesicle pools. Furthermore, Ca2+ imaging demonstrated ∼2-fold greater Ca2+ influx at phasic neuron release sites relative to tonic, along with an enhanced synaptic vesicle coupling. Finally, confocal and super-resolution imaging revealed that phasic neuron release sites are organized in a more compact arrangement, with enhanced stoichiometry of voltage-gated Ca2+ channels relative to other active zone scaffolds. These data suggest that distinctions in active zone nano-architecture and Ca2+ influx collaborate to differentially tune glutamate release at tonic versus phasic synaptic subtypes.SIGNIFICANCE STATEMENT "Tonic" and "phasic" neuronal subtypes, based on differential firing properties, are common across many nervous systems. Using a recently developed approach to selectively silence transmission from one of these two neurons, we reveal specialized synaptic functional and structural properties that distinguish these specialized neurons. This study provides important insights into how input-specific synaptic diversity is achieved, which could have implications for neurologic disorders that involve changes in synaptic function.
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Affiliation(s)
- Kaikai He
- Department of Neurobiology, University of Southern California, Los Angeles, California 90089
- USC Neuroscience Graduate Program, Los Angeles, California 90089
| | - Yifu Han
- Department of Neurobiology, University of Southern California, Los Angeles, California 90089
- USC Neuroscience Graduate Program, Los Angeles, California 90089
| | - Xiling Li
- Department of Neurobiology, University of Southern California, Los Angeles, California 90089
- USC Neuroscience Graduate Program, Los Angeles, California 90089
| | - Roberto X Hernandez
- Integrative Biology and Neuroscience Graduate Program, Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida 33431
- International Max Planck Research School for Brain and Behavior, Jupiter, Florida 33458
| | - Danielle V Riboul
- Integrative Biology Graduate Program, Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida 33431
| | - Touhid Feghhi
- Department of Physics, Florida Atlantic University, Boca Raton, Florida 33431
| | - Karlis A Justs
- Integrative Biology and Neuroscience Graduate Program, Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida 33431
| | - Olena Mahneva
- Wilkes Honors College, Florida Atlantic University, Jupiter, Florida 33458
| | - Sarah Perry
- Department of Neurobiology, University of Southern California, Los Angeles, California 90089
| | - Gregory T Macleod
- Wilkes Honors College, Florida Atlantic University, Jupiter, Florida 33458
- Institute for Human Health and Disease Intervention, Florida Atlantic University, Jupiter, Florida 33458
| | - Dion Dickman
- Department of Neurobiology, University of Southern California, Los Angeles, California 90089
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McAlpine LS, Lifland B, Check JR, Angarita GA, Ngo TT, Chen P, Dandekar R, Alvarenga BD, Browne WD, Pleasure SJ, Wilson MR, Spudich SS, Farhadian SF, Bartley CM. Anti-SARS-CoV-2 and Autoantibody Profiling of a COVID-19 Patient With Subacute Psychosis Who Remitted After Treatment With Intravenous Immunoglobulin. Biol Psychiatry 2023; 93:e25-e29. [PMID: 36481066 PMCID: PMC9722219 DOI: 10.1016/j.biopsych.2022.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 09/07/2022] [Indexed: 12/12/2022]
Affiliation(s)
- Lindsay S McAlpine
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut
| | - Brooke Lifland
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut
| | - Joseph R Check
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut
| | - Gustavo A Angarita
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut
| | - Thomas T Ngo
- Weill Institute for Neurosciences, University of California, San Francisco, California; Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, California
| | - Peixi Chen
- Weill Institute for Neurosciences, University of California, San Francisco, California; Department of Neurology, University of California, San Francisco, California
| | - Ravi Dandekar
- Weill Institute for Neurosciences, University of California, San Francisco, California; Department of Neurology, University of California, San Francisco, California
| | - Bonny D Alvarenga
- Weill Institute for Neurosciences, University of California, San Francisco, California; Department of Neurology, University of California, San Francisco, California
| | - Weston D Browne
- Weill Institute for Neurosciences, University of California, San Francisco, California; Department of Neurology, University of California, San Francisco, California
| | - Samuel J Pleasure
- Weill Institute for Neurosciences, University of California, San Francisco, California; Department of Neurology, University of California, San Francisco, California
| | - Michael R Wilson
- Weill Institute for Neurosciences, University of California, San Francisco, California; Department of Neurology, University of California, San Francisco, California
| | - Serena S Spudich
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut
| | - Shelli F Farhadian
- Department of Internal Medicine, Section of Infectious Diseases, Yale School of Medicine, New Haven, Connecticut
| | - Christopher M Bartley
- Weill Institute for Neurosciences, University of California, San Francisco, California; Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, California.
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Overduin M, Tran A, Eekels DM, Overduin F, Kervin TA. Transmembrane Membrane Readers form a Novel Class of Proteins That Include Peripheral Phosphoinositide Recognition Domains and Viral Spikes. MEMBRANES 2022; 12:1161. [PMID: 36422153 PMCID: PMC9692390 DOI: 10.3390/membranes12111161] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 11/11/2022] [Accepted: 11/15/2022] [Indexed: 06/16/2023]
Abstract
Membrane proteins are broadly classified as transmembrane (TM) or peripheral, with functions that pertain to only a single bilayer at a given time. Here, we explicate a class of proteins that contain both transmembrane and peripheral domains, which we dub transmembrane membrane readers (TMMRs). Their transmembrane and peripheral elements anchor them to one bilayer and reversibly attach them to another section of bilayer, respectively, positioning them to tether and fuse membranes while recognizing signals such as phosphoinositides (PIs) and modifying lipid chemistries in proximity to their transmembrane domains. Here, we analyze full-length models from AlphaFold2 and Rosetta, as well as structures from nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography, using the Membrane Optimal Docking Area (MODA) program to map their membrane-binding surfaces. Eukaryotic TMMRs include phospholipid-binding C1, C2, CRAL-TRIO, FYVE, GRAM, GTPase, MATH, PDZ, PH, PX, SMP, StART and WD domains within proteins including protrudin, sorting nexins and synaptotagmins. The spike proteins of SARS-CoV-2 as well as other viruses are also TMMRs, seeing as they are anchored into the viral membrane while mediating fusion with host cell membranes. As such, TMMRs have key roles in cell biology and membrane trafficking, and include drug targets for diseases such as COVID-19.
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Affiliation(s)
- Michael Overduin
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Anh Tran
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | | | - Finn Overduin
- Institute of Nutritional Science, University of Potsdam, 14476 Potsdam, Germany
| | - Troy A. Kervin
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
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8
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Mercury Induced Tissue Damage, Redox Metabolism, Ion Transport, Apoptosis, and Intestinal Microbiota Change in Red Swamp Crayfish (Procambarus clarkii): Application of Multi-Omics Analysis in Risk Assessment of Hg. Antioxidants (Basel) 2022; 11:antiox11101944. [PMID: 36290667 PMCID: PMC9598479 DOI: 10.3390/antiox11101944] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/22/2022] [Accepted: 09/24/2022] [Indexed: 11/22/2022] Open
Abstract
As one of the most toxic elements, mercury (Hg) is a widespread toxicant in aquatic environments. Crayfish are considered suitable for indicating the impact of heavy metals on aquatic crustaceans. Nevertheless, Hg toxicity on Procambarus clarkii is largely unknown. In this research, the acute Hg-induced alterations of biochemical responses, histopathology, hepatopancreatic transcriptome, and intestinal microbiome of Procambarus clarkii were studied. Firstly, Hg induced significant changes in reactive oxygen species (ROS) and malonaldehyde (MDA) content as well as antioxidant enzyme activity. Secondly, Hg exposure caused structural damage to the hepatopancreas (e.g., vacuolization of the epithelium and dilatation of the lumen) as well as to the intestines (e.g., dysregulation of lamina epithelialises and extension of lamina proprias). Thirdly, after treatment with three different concentrations of Hg, RNA-seq assays of the hepatopancreas revealed a large number of differentially expressed genes (DEGs) linked to a specific function. Among the DEGs, a lot of redox metabolism- (e.g., ACOX3, SMOX, GPX3, GLO1, and P4HA1), ion transport- (e.g., MICU3, MCTP, PYX, STEAP3, and SLC30A2), drug metabolism- (e.g., HSP70, HSP90A, CYP2L1, and CYP9E2), immune response- (e.g., SMAD4, HDAC1, and DUOX), and apoptosis-related genes (e.g., CTSL, CASP7, and BIRC2) were identified, which suggests that Hg exposure may perturb the redox equilibrium, disrupt the ion homeostasis, weaken immune response and ability, and cause apoptosis. Fourthly, bacterial 16S rRNA gene sequencing showed that Hg exposure decreased bacterial diversity and dysregulated intestinal microbiome composition. At the phylum level, there was a marked decrease in Proteobacteria and an increase in Firmicutes after exposure to high levels of Hg. With regards to genus, abundances of Bacteroides, Dysgonomonas, and Arcobacter were markedly dysregulated after Hg exposures. Our findings elucidate the mechanisms involved in Hg-mediated toxicity in aquatic crustaceans at the tissue, cellular, molecular as well as microbial levels.
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9
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IGF-1 receptor regulates upward firing rate homeostasis via the mitochondrial calcium uniporter. Proc Natl Acad Sci U S A 2022; 119:e2121040119. [PMID: 35943986 PMCID: PMC9388073 DOI: 10.1073/pnas.2121040119] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
An emerging hypothesis is that neuronal circuits homeostatically maintain a stable spike rate despite continuous environmental changes. This firing rate homeostasis is believed to confer resilience to neurodegeneration and cognitive decline. We show that insulin-like growth factor-1 receptor (IGF-1R) is necessary for homeostatic response of mean firing rate to inactivity, termed “upward firing rate homeostasis.” We show that its mechanism of action is to couple spike bursts with downstream mitochondrial Ca2+ influx via the mitochondrial calcium uniporter complex (MCUc). We propose that MCUc is a homeostatic Ca2+ sensor that triggers the integrated homeostatic response. Firing rate homeostasis may be the principal mechanism by which IGF-1R regulates aging and neurodevelopmental and neurodegenerative disorders. Regulation of firing rate homeostasis constitutes a fundamental property of central neural circuits. While intracellular Ca2+ has long been hypothesized to be a feedback control signal, the molecular machinery enabling a network-wide homeostatic response remains largely unknown. We show that deletion of insulin-like growth factor-1 receptor (IGF-1R) limits firing rate homeostasis in response to inactivity, without altering the distribution of baseline firing rates. The deficient firing rate homeostatic response was due to disruption of both postsynaptic and intrinsic plasticity. At the cellular level, we detected a fraction of IGF-1Rs in mitochondria, colocalized with the mitochondrial calcium uniporter complex (MCUc). IGF-1R deletion suppressed transcription of the MCUc members and burst-evoked mitochondrial Ca2+ (mitoCa2+) by weakening mitochondria-to-cytosol Ca2+ coupling. Overexpression of either mitochondria-targeted IGF-1R or MCUc in IGF-1R–deficient neurons was sufficient to rescue the deficits in burst-to-mitoCa2+ coupling and firing rate homeostasis. Our findings indicate that mitochondrial IGF-1R is a key regulator of the integrated homeostatic response by tuning the reliability of burst transfer by MCUc. Based on these results, we propose that MCUc acts as a homeostatic Ca2+ sensor. Faulty activation of MCUc may drive dysregulation of firing rate homeostasis in aging and in brain disorders associated with aberrant IGF-1R/MCUc signaling.
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10
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Téllez-Arreola JL, Martínez-Torres A, Flores-Moran AE, Lazaro-Guevara JM, Estrada-Mondragón A. Analysis of the MCTP Amino Acid Sequence Reveals the Conservation of Putative Calcium- and Lipid-Binding Pockets Within the C2 Domains In Silico. J Mol Evol 2022; 90:271-282. [PMID: 35604448 DOI: 10.1007/s00239-022-10057-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 05/10/2022] [Indexed: 11/24/2022]
Abstract
MCTPs (Multiple C2 Domains and Transmembrane region Proteins) are evolutionarily and structurally related to other C2 proteins, which are central to exocytosis and membrane trafficking; however, their specific function has been little studied. MCTPs are associated with endosomes and the endoplasmic reticulum and possess three C2 domains (C2A-C2C) and two transmembrane regions (TMRs) well conserved in different species. Here, we generated structural models of the MCTP C2 domains of C. elegans and analyzed their putative function by docking, which revealed that these domains possess Ca2+- and lipid-binding pockets, suggesting that MCTPs play a significant, calcium-dependent role in membrane physiology.
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Affiliation(s)
- José Luis Téllez-Arreola
- Departamento de Neurobiología Celular Y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, 76215, Juriquilla, Querétaro, México.
| | - Ataúlfo Martínez-Torres
- Departamento de Neurobiología Celular Y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, 76215, Juriquilla, Querétaro, México
| | - Adriana E Flores-Moran
- Unit for Basic and Applied Microbiology, School of Natural Sciences, Autonomous University of Queretaro, Queretaro, Mexico
| | - José M Lazaro-Guevara
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA.,Department of Botany, University of British Columbia, Vancouver, BC, Canada.,Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Argel Estrada-Mondragón
- Department of Biomedical and Clinical Sciences (BKV), Linköping University, 581 83, Linköping, Sweden.
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11
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Nair AG, Muttathukunnel P, Müller M. Distinct molecular pathways govern presynaptic homeostatic plasticity. Cell Rep 2021; 37:110105. [PMID: 34910905 PMCID: PMC8692748 DOI: 10.1016/j.celrep.2021.110105] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 10/05/2021] [Accepted: 11/16/2021] [Indexed: 11/30/2022] Open
Abstract
Presynaptic homeostatic plasticity (PHP) stabilizes synaptic transmission by counteracting impaired neurotransmitter receptor function through neurotransmitter release potentiation. PHP is thought to be triggered by impaired receptor function and to involve a stereotypic signaling pathway. However, here we demonstrate that different receptor perturbations that similarly reduce synaptic transmission result in different responses at the Drosophila neuromuscular junction. While receptor inhibition by the glutamate receptor (GluR) antagonist γ-D-glutamylglycine (γDGG) is not compensated by PHP, the GluR inhibitors Philanthotoxin-433 (PhTx) and Gyki-53655 (Gyki) induce compensatory PHP. Intriguingly, PHP triggered by PhTx and Gyki involve separable signaling pathways, including inhibition of distinct GluR subtypes, differential modulation of the active-zone scaffold Bruchpilot, and short-term plasticity. Moreover, while PHP upon Gyki treatment does not require genes promoting PhTx-induced PHP, it involves presynaptic protein kinase D. Thus, synapses not only respond differentially to similar activity impairments, but achieve homeostatic compensation via distinct mechanisms, highlighting the diversity of homeostatic signaling.
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Affiliation(s)
- Anu G Nair
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; Department of Neuroscience, Karolinska Institute, 17177 Stockholm, Sweden
| | - Paola Muttathukunnel
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; Neuroscience Center Zurich, University of Zurich/ETH Zurich, 8057 Zurich, Switzerland
| | - Martin Müller
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; Neuroscience Center Zurich, University of Zurich/ETH Zurich, 8057 Zurich, Switzerland.
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12
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Yeates CJ, Frank CA. Homeostatic Depression Shows Heightened Sensitivity to Synaptic Calcium. Front Cell Neurosci 2021; 15:618393. [PMID: 34025355 PMCID: PMC8139420 DOI: 10.3389/fncel.2021.618393] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 04/13/2021] [Indexed: 12/18/2022] Open
Abstract
Synapses and circuits rely on homeostatic forms of regulation in order to transmit meaningful information. The Drosophila melanogaster neuromuscular junction (NMJ) is a well-studied synapse that shows robust homeostatic control of function. Most prior studies of homeostatic plasticity at the NMJ have centered on presynaptic homeostatic potentiation (PHP). PHP happens when postsynaptic muscle neurotransmitter receptors are impaired, triggering retrograde signaling that causes an increase in presynaptic neurotransmitter release. As a result, normal levels of evoked excitation are maintained. The counterpart to PHP at the NMJ is presynaptic homeostatic depression (PHD). Overexpression of the Drosophila vesicular glutamate transporter (VGlut) causes an increase in the amplitude of spontaneous events. PHD happens when the synapse responds to the challenge by decreasing quantal content (QC) during evoked neurotransmissionagain, resulting in normal levels of postsynaptic excitation. We hypothesized that there may exist a class of molecules that affects both PHP and PHD. Impairment of any such molecule could hurt a synapses ability to respond to any significant homeostatic challenge. We conducted an electrophysiology-based screen for blocks of PHD. We did not observe a block of PHD in the genetic conditions screened, but we found loss-of-function conditions that led to a substantial deficit in evoked amplitude when combined with VGlut overexpression. The conditions causing this phenotype included a double heterozygous loss-of-function condition for genes encoding the inositol trisphosphate receptor (IP3R itpr) and ryanodine receptor (RyR). IP3Rs and RyRs gate calcium release from intracellular stores. Pharmacological agents targeting IP3R and RyR recapitulated the genetic losses of these factors, as did lowering calcium levels from other sources. Our data are consistent with the idea that the homeostatic signaling process underlying PHD is especially sensitive to levels of calcium at the presynapse.
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Affiliation(s)
- Catherine J Yeates
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, IA, United States.,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA, United States
| | - C Andrew Frank
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, IA, United States.,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA, United States.,Iowa Neuroscience Institute, University of Iowa Carver College of Medicine, Iowa City, IA, United States
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13
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Function of Drosophila Synaptotagmins in membrane trafficking at synapses. Cell Mol Life Sci 2021; 78:4335-4364. [PMID: 33619613 PMCID: PMC8164606 DOI: 10.1007/s00018-021-03788-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/29/2021] [Accepted: 02/09/2021] [Indexed: 12/13/2022]
Abstract
The Synaptotagmin (SYT) family of proteins play key roles in regulating membrane trafficking at neuronal synapses. Using both Ca2+-dependent and Ca2+-independent interactions, several SYT isoforms participate in synchronous and asynchronous fusion of synaptic vesicles (SVs) while preventing spontaneous release that occurs in the absence of stimulation. Changes in the function or abundance of the SYT1 and SYT7 isoforms alter the number and route by which SVs fuse at nerve terminals. Several SYT family members also regulate trafficking of other subcellular organelles at synapses, including dense core vesicles (DCV), exosomes, and postsynaptic vesicles. Although SYTs are linked to trafficking of multiple classes of synaptic membrane compartments, how and when they interact with lipids, the SNARE machinery and other release effectors are still being elucidated. Given mutations in the SYT family cause disorders in both the central and peripheral nervous system in humans, ongoing efforts are defining how these proteins regulate vesicle trafficking within distinct neuronal compartments. Here, we review the Drosophila SYT family and examine their role in synaptic communication. Studies in this invertebrate model have revealed key similarities and several differences with the predicted activity of their mammalian counterparts. In addition, we highlight the remaining areas of uncertainty in the field and describe outstanding questions on how the SYT family regulates membrane trafficking at nerve terminals.
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14
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Hu Q, Zeng M, Wang M, Huang X, Li J, Feng C, Xuan L, Liu L, Huang G. Family-Wide Evaluation of Multiple C2 Domain and Transmembrane Region Protein in Gossypium hirsutum. FRONTIERS IN PLANT SCIENCE 2021; 12:767667. [PMID: 34759949 PMCID: PMC8573151 DOI: 10.3389/fpls.2021.767667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 09/27/2021] [Indexed: 05/17/2023]
Abstract
Multiple C2 domain and transmembrane region proteins (MCTPs) are a group of evolutionarily conserved proteins and show emerging roles in mediating protein trafficking and signaling transduction. Although, several studies showed that MCTPs play important roles during plant growth and development, their biological functions in cotton remain largely unknown. Here, we identify and characterize 33 GhMCTP genes from upland cotton (Gossypium hirsutum) and reveal the diverse expression patterns of GhMCTPs in various tissues. We also find that GhMCTP7, GhMCTP12, and GhMCTP17 are highly expressed in the main stem apex, suggesting their possible roles in shoot development. Through analyzing different cotton species, we discover plant heights are closely related to the expression levels of GhMCTP7, GhMCTP12, and GhMCTP17. Furthermore, we silence the expression of GhMCTP genes using virus-induced gene silencing (VIGS) system in cotton and find that GhMCTP7, GhMCTP12, and GhMCTP17 play an essential role in shoot meristem development. GhMCTPs interact with GhKNAT1 and GhKNAT2 and regulate meristem development through integrating multiple signal pathways. Taken together, our results demonstrate functional redundancy of GhMCTPs in cotton shoot meristem development and provide a valuable resource to further study various functions of GhMCTPs in plant growth and development.
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Affiliation(s)
- Qianqian Hu
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Mengting Zeng
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Miao Wang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Xiaoyu Huang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Jiayi Li
- Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Changhui Feng
- Institute of Cash Crops, Hubei Academy of Agricultural Sciences, Wuhan, China
| | - Lijie Xuan
- Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Lu Liu
- Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
- Lu Liu,
| | - Gengqing Huang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
- Xinjiang Key Laboratory of Special Species Conservation and Regulatory Biology, College of Life Science, Xinjiang Normal University, Ürümqi, China
- *Correspondence: Gengqing Huang,
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15
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Téllez-Arreola JL, Silva M, Martínez-Torres A. MCTP-1 modulates neurotransmitter release in C. elegans. Mol Cell Neurosci 2020; 107:103528. [PMID: 32650044 DOI: 10.1016/j.mcn.2020.103528] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 06/17/2020] [Accepted: 06/23/2020] [Indexed: 11/30/2022] Open
Abstract
Multiple C2 and Transmembrane Domain Proteins (MCTPs) are putative calcium sensors. Proteins that contain C2 domains play essential roles in membrane trafficking and exocytosis; however, MCTPs functions in neurotransmitter release are not known. Here we report that in C. elegans mctp-1 is under the control of two promoters - one active in the nervous system and the second in the spermatheca. We generated and characterized a loss of function amt1 mutant and compared it to a previously published loss of function mutant (av112). Loss of mctp-1 function causes defects in egg-laying, crawling velocity, and thrashing rates. Both amt1 and av112 mutants are hyposensitive to the acetylcholinesterase blocker aldicarb, suggesting that MCTP-1 may play a role in synaptic vesicle release.
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Affiliation(s)
- José Luis Téllez-Arreola
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, C.P. 76215 Juriquilla, Querétaro, México; School of Biological Sciences, University of Utah, Salt Lake City, United States
| | - Malan Silva
- School of Biological Sciences, University of Utah, Salt Lake City, United States
| | - Ataúlfo Martínez-Torres
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, C.P. 76215 Juriquilla, Querétaro, México.
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16
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Genç Ö, An JY, Fetter RD, Kulik Y, Zunino G, Sanders SJ, Davis GW. Homeostatic plasticity fails at the intersection of autism-gene mutations and a novel class of common genetic modifiers. eLife 2020; 9:55775. [PMID: 32609087 PMCID: PMC7394548 DOI: 10.7554/elife.55775] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 06/07/2020] [Indexed: 01/08/2023] Open
Abstract
We identify a set of common phenotypic modifiers that interact with five independent autism gene orthologs (RIMS1, CHD8, CHD2, WDFY3, ASH1L) causing a common failure of presynaptic homeostatic plasticity (PHP) in Drosophila. Heterozygous null mutations in each autism gene are demonstrated to have normal baseline neurotransmission and PHP. However, PHP is sensitized and rendered prone to failure. A subsequent electrophysiology-based genetic screen identifies the first known heterozygous mutations that commonly genetically interact with multiple ASD gene orthologs, causing PHP to fail. Two phenotypic modifiers identified in the screen, PDPK1 and PPP2R5D, are characterized. Finally, transcriptomic, ultrastructural and electrophysiological analyses define one mechanism by which PHP fails; an unexpected, maladaptive up-regulation of CREG, a conserved, neuronally expressed, stress response gene and a novel repressor of PHP. Thus, we define a novel genetic landscape by which diverse, unrelated autism risk genes may converge to commonly affect the robustness of synaptic transmission.
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Affiliation(s)
- Özgür Genç
- Department of Biochemistry and Biophysics Kavli Institute for Fundamental Neuroscience University of California, San Francisco, San Francisco, United States
| | - Joon-Yong An
- Department of Psychiatry UCSF Weill Institute for Neurosciences University of California, San Francisco, San Francisco, United States.,School of Biosystem and Biomedical Science, College of Health Science, Korea University, Seoul, Republic of Korea
| | - Richard D Fetter
- Department of Biochemistry and Biophysics Kavli Institute for Fundamental Neuroscience University of California, San Francisco, San Francisco, United States
| | - Yelena Kulik
- Department of Biochemistry and Biophysics Kavli Institute for Fundamental Neuroscience University of California, San Francisco, San Francisco, United States
| | - Giulia Zunino
- Department of Biochemistry and Biophysics Kavli Institute for Fundamental Neuroscience University of California, San Francisco, San Francisco, United States
| | - Stephan J Sanders
- Department of Psychiatry UCSF Weill Institute for Neurosciences University of California, San Francisco, San Francisco, United States
| | - Graeme W Davis
- Department of Biochemistry and Biophysics Kavli Institute for Fundamental Neuroscience University of California, San Francisco, San Francisco, United States
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17
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Hao P, Wang H, Ma L, Wu A, Chen P, Cheng S, Wei H, Yu S. Genome-wide identification and characterization of multiple C2 domains and transmembrane region proteins in Gossypium hirsutum. BMC Genomics 2020; 21:445. [PMID: 32600247 PMCID: PMC7325108 DOI: 10.1186/s12864-020-06842-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 06/16/2020] [Indexed: 11/10/2022] Open
Abstract
Background Multiple C2 domains and transmembrane region proteins (MCTPs) may act as transport mediators of other regulators. Although increased number of MCTPs in higher plants implies their diverse and specific functions in plant growth and development, only a few plant MCTPs have been studied and no study on the MCTPs in cotton has been reported. Results In this study, we identified 31 MCTPs in G. hirsutum, which were classified into five subfamilies according to the phylogenetic analysis. GhMCTPs from subfamily V exhibited isoelectric points (pIs) less than 7, whereas GhMCTPs from subfamily I, II, III and IV exhibited pIs more than 7.5, implying their distinct biological functions. In addition, GhMCTPs within subfamily III, IV and V exhibited more diverse physicochemical properties, domain architectures and expression patterns than GhMCTPs within subfamily I and II, suggesting that GhMCTPs within subfamily III, IV and V diverged to perform more diverse and specific functions. Analyses of conserved motifs and pIs indicated that the N-terminus was more divergent than the C-terminus and GhMCTPs’ functional divergence might be mainly contributed by the N-terminus. Furthermore, yeast two-hybrid assay indicated that the N-terminus was responsible to interact with target proteins. Phylogenetic analysis classified multiple N-terminal C2 domains into four subclades, suggesting that these C2 domains performed different molecular functions in mediating the transport of target proteins. Conclusions Our systematic characterization of MCTPs in G. hirsutum will provide helpful information to further research GhMCTPs’ molecular roles in mediating other regulators’ transport to coordinate growth and development of various cotton tissues.
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Affiliation(s)
- Pengbo Hao
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000, China.,College of Agronomy, Northwest A&F University, Yangling, 712100, China
| | - Hantao Wang
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000, China
| | - Liang Ma
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000, China
| | - Aimin Wu
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000, China
| | - Pengyun Chen
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000, China
| | - Shuaishuai Cheng
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000, China.,College of Agronomy, Northwest A&F University, Yangling, 712100, China
| | - Hengling Wei
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000, China.
| | - Shuxun Yu
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000, China. .,College of Agronomy, Northwest A&F University, Yangling, 712100, China.
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18
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Abstract
Ferlins are multiple-C2-domain proteins involved in Ca2+-triggered membrane dynamics within the secretory, endocytic and lysosomal pathways. In bony vertebrates there are six ferlin genes encoding, in humans, dysferlin, otoferlin, myoferlin, Fer1L5 and 6 and the long noncoding RNA Fer1L4. Mutations in DYSF (dysferlin) can cause a range of muscle diseases with various clinical manifestations collectively known as dysferlinopathies, including limb-girdle muscular dystrophy type 2B (LGMD2B) and Miyoshi myopathy. A mutation in MYOF (myoferlin) was linked to a muscular dystrophy accompanied by cardiomyopathy. Mutations in OTOF (otoferlin) can be the cause of nonsyndromic deafness DFNB9. Dysregulated expression of any human ferlin may be associated with development of cancer. This review provides a detailed description of functions of the vertebrate ferlins with a focus on muscle ferlins and discusses the mechanisms leading to disease development.
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19
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Öztürk Z, O’Kane CJ, Pérez-Moreno JJ. Axonal Endoplasmic Reticulum Dynamics and Its Roles in Neurodegeneration. Front Neurosci 2020; 14:48. [PMID: 32116502 PMCID: PMC7025499 DOI: 10.3389/fnins.2020.00048] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 01/13/2020] [Indexed: 12/13/2022] Open
Abstract
The physical continuity of axons over long cellular distances poses challenges for their maintenance. One organelle that faces this challenge is endoplasmic reticulum (ER); unlike other intracellular organelles, this forms a physically continuous network throughout the cell, with a single membrane and a single lumen. In axons, ER is mainly smooth, forming a tubular network with occasional sheets or cisternae and low amounts of rough ER. It has many potential roles: lipid biosynthesis, glucose homeostasis, a Ca2+ store, protein export, and contacting and regulating other organelles. This tubular network structure is determined by ER-shaping proteins, mutations in some of which are causative for neurodegenerative disorders such as hereditary spastic paraplegia (HSP). While axonal ER shares many features with the tubular ER network in other contexts, these features must be adapted to the long and narrow dimensions of axons. ER appears to be physically continuous throughout axons, over distances that are enormous on a subcellular scale. It is therefore a potential channel for long-distance or regional communication within neurons, independent of action potentials or physical transport of cargos, but involving its physiological roles such as Ca2+ or organelle homeostasis. Despite its apparent stability, axonal ER is highly dynamic, showing features like anterograde and retrograde transport, potentially reflecting continuous fusion and breakage of the network. Here we discuss the transport processes that must contribute to this dynamic behavior of ER. We also discuss the model that these processes underpin a homeostatic process that ensures both enough ER to maintain continuity of the network and repair breaks in it, but not too much ER that might disrupt local cellular physiology. Finally, we discuss how failure of ER organization in axons could lead to axon degenerative diseases, and how a requirement for ER continuity could make distal axons most susceptible to degeneration in conditions that disrupt ER continuity.
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Affiliation(s)
| | - Cahir J. O’Kane
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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20
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Espino-Saldaña AE, Durán-Ríos K, Olivares-Hernandez E, Rodríguez-Ortiz R, Arellano-Carbajal F, Martínez-Torres A. Temporal and spatial expression of zebrafish mctp genes and evaluation of frameshift alleles of mctp2b. Gene 2020; 738:144371. [PMID: 32001375 DOI: 10.1016/j.gene.2020.144371] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 01/11/2020] [Accepted: 01/13/2020] [Indexed: 01/28/2023]
Abstract
MCTPs (multiple C2 domain proteins with two transmembrane regions) have been proposed as novel endoplasmic reticulum calcium sensors; however, their function remains largely unknown. Here we report the structure of the four mctp genes from zebrafish (mctp1a, mctp1b, mctp2a and mctp2b), their diversity, expression pattern during embryonic development and in adult tissue and the effect of knocking down the expression of Mctp2b by CRISPR/Cas9. The four mctp genes are expressed from early development and exhibit differential expression patterns but are found mainly in the nervous and muscular systems. Mctp2b tagged with fluorescent proteins and expressed in HEK-293 cells and neurons of the fish spinal cord localized mostly in the endoplasmic reticulum but also in lysosomes and late and recycling endosomes. Knocking down mctp2b expression impaired embryonic development, suggesting that the functional participation of this gene is relevant, at least during the early stages of development.
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Affiliation(s)
- Angeles E Espino-Saldaña
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Departamento de Neurobiología Celular y Molecular, Laboratorio de Neurobiología Molecular y Celular, Juriquilla, Querétaro, 76230, Mexico; Universidad Autónoma de Querétaro, Facultad de Ciencias Naturales, Av. de las Ciencias S/N, Querétaro, Mexico
| | - Karina Durán-Ríos
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Departamento de Neurobiología Celular y Molecular, Laboratorio de Neurobiología Molecular y Celular, Juriquilla, Querétaro, 76230, Mexico
| | - Eduardo Olivares-Hernandez
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Departamento de Neurobiología Celular y Molecular, Laboratorio de Neurobiología Molecular y Celular, Juriquilla, Querétaro, 76230, Mexico
| | - Roberto Rodríguez-Ortiz
- CONACYT- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Departamento de Neurobiología Celular y Molecular, Laboratorio de Neurobiología Molecular y Celular, Juriquilla, Querétaro, 76230, Mexico
| | - Fausto Arellano-Carbajal
- Universidad Autónoma de Querétaro, Facultad de Ciencias Naturales, Av. de las Ciencias S/N, Querétaro, Mexico
| | - Ataulfo Martínez-Torres
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Departamento de Neurobiología Celular y Molecular, Laboratorio de Neurobiología Molecular y Celular, Juriquilla, Querétaro, 76230, Mexico.
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21
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Spatiotemporal model of tripartite synapse with perinodal astrocytic process. J Comput Neurosci 2019; 48:1-20. [DOI: 10.1007/s10827-019-00734-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Revised: 10/11/2019] [Accepted: 10/21/2019] [Indexed: 12/30/2022]
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22
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Genç Ö, Davis GW. Target-wide Induction and Synapse Type-Specific Robustness of Presynaptic Homeostasis. Curr Biol 2019; 29:3863-3873.e2. [PMID: 31708391 PMCID: PMC7518040 DOI: 10.1016/j.cub.2019.09.036] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 09/08/2019] [Accepted: 09/13/2019] [Indexed: 11/23/2022]
Abstract
Presynaptic homeostatic plasticity (PHP) is an evolutionarily conserved form of adaptive neuromodulation and is observed at both central and peripheral synapses. In this work, we make several fundamental advances by interrogating the synapse specificity of PHP. We define how PHP remains robust to acute versus long-term neurotransmitter receptor perturbation. We describe a general PHP property that includes global induction and synapse-specific expression mechanisms. Finally, we detail a novel synapse-specific PHP expression mechanism that enables the conversion from short- to long-term PHP expression. If our data can be extended to other systems, including the mammalian central nervous system, they suggest that PHP can be broadly induced and expressed to sustain the function of complex neural circuitry.
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Affiliation(s)
- Özgür Genç
- Department of Biochemistry and Biophysics, Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Graeme W Davis
- Department of Biochemistry and Biophysics, Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA.
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23
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Frank CA, James TD, Müller M. Homeostatic control of Drosophila neuromuscular junction function. Synapse 2019; 74:e22133. [PMID: 31556149 PMCID: PMC6817395 DOI: 10.1002/syn.22133] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 09/05/2019] [Accepted: 09/19/2019] [Indexed: 02/06/2023]
Abstract
The ability to adapt to changing internal and external conditions is a key feature of biological systems. Homeostasis refers to a regulatory process that stabilizes dynamic systems to counteract perturbations. In the nervous system, homeostatic mechanisms control neuronal excitability, neurotransmitter release, neurotransmitter receptors, and neural circuit function. The neuromuscular junction (NMJ) of Drosophila melanogaster has provided a wealth of molecular information about how synapses implement homeostatic forms of synaptic plasticity, with a focus on the transsynaptic, homeostatic modulation of neurotransmitter release. This review examines some of the recent findings from the Drosophila NMJ and highlights questions the field will ponder in coming years.
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Affiliation(s)
- C Andrew Frank
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA.,Interdisciplinary Programs in Neuroscience, Genetics, and Molecular Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Thomas D James
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA.,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, Iowa, USA
| | - Martin Müller
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland.,Neuroscience Center Zurich, Zurich, Switzerland
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24
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James TD, Zwiefelhofer DJ, Frank CA. Maintenance of homeostatic plasticity at the Drosophila neuromuscular synapse requires continuous IP 3-directed signaling. eLife 2019; 8:39643. [PMID: 31180325 PMCID: PMC6557630 DOI: 10.7554/elife.39643] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 05/27/2019] [Indexed: 12/18/2022] Open
Abstract
Synapses and circuits rely on neuroplasticity to adjust output and meet physiological needs. Forms of homeostatic synaptic plasticity impart stability at synapses by countering destabilizing perturbations. The Drosophila melanogaster larval neuromuscular junction (NMJ) is a model synapse with robust expression of homeostatic plasticity. At the NMJ, a homeostatic system detects impaired postsynaptic sensitivity to neurotransmitter and activates a retrograde signal that restores synaptic function by adjusting neurotransmitter release. This process has been separated into temporally distinct phases, induction and maintenance. One prevailing hypothesis is that a shared mechanism governs both phases. Here, we show the two phases are separable. Combining genetics, pharmacology, and electrophysiology, we find that a signaling system consisting of PLCβ, inositol triphosphate (IP3), IP3 receptors, and Ryanodine receptors is required only for the maintenance of homeostatic plasticity. We also find that the NMJ is capable of inducing homeostatic signaling even when its sustained maintenance process is absent. Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).
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Affiliation(s)
- Thomas D James
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, United States.,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, United States
| | - Danielle J Zwiefelhofer
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, United States
| | - C Andrew Frank
- Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, United States.,Interdisciplinary Programs in Neuroscience, Genetics and Molecular Medicine, University of Iowa, Iowa City, United States
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25
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Petit JD, Immel F, Lins L, Bayer EM. Lipids or Proteins: Who Is Leading the Dance at Membrane Contact Sites? FRONTIERS IN PLANT SCIENCE 2019; 10:198. [PMID: 30846999 PMCID: PMC6393330 DOI: 10.3389/fpls.2019.00198] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 02/05/2019] [Indexed: 05/19/2023]
Abstract
Understanding the mode of action of membrane contact sites (MCSs) across eukaryotic organisms at the near-atomic level to infer function at the cellular and tissue levels is a challenge scientists are currently facing. These peculiar systems dedicated to inter-organellar communication are perfect examples of cellular processes where the interplay between lipids and proteins is critical. In this mini review, we underline the link between membrane lipid environment, the recruitment of proteins at specialized membrane domains and the function of MCSs. More precisely, we want to give insights on the crucial role of lipids in defining the specificity of plant endoplasmic reticulum (ER)-plasma membrane (PM) MCSs and we further propose approaches to study them at multiple scales. Our goal is not so much to go into detailed description of MCSs, as there are numerous focused reviews on the subject, but rather try to pinpoint the critical elements defining those structures and give an original point of view by considering the subject from a near-atomic angle with a focus on lipids. We review current knowledge as to how lipids can define MCS territories, play a role in the recruitment and function of the MCS-associated proteins and in turn, how the lipid environment can be modified by proteins.
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Affiliation(s)
- Jules D. Petit
- UMR5200 CNRS, Laboratory of Membrane Biogenesis, University of Bordeaux, Villenave d’Ornon, France
- Laboratoire de Biophysique Moléculaire aux Interfaces, TERRA Research Centre, GX ABT, Université de Liège, Liège, Belgium
| | - Françoise Immel
- UMR5200 CNRS, Laboratory of Membrane Biogenesis, University of Bordeaux, Villenave d’Ornon, France
| | - Laurence Lins
- Laboratoire de Biophysique Moléculaire aux Interfaces, TERRA Research Centre, GX ABT, Université de Liège, Liège, Belgium
| | - Emmanuelle M. Bayer
- UMR5200 CNRS, Laboratory of Membrane Biogenesis, University of Bordeaux, Villenave d’Ornon, France
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26
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Delvendahl I, Müller M. Homeostatic plasticity—a presynaptic perspective. Curr Opin Neurobiol 2019; 54:155-162. [DOI: 10.1016/j.conb.2018.10.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 10/04/2018] [Indexed: 01/05/2023]
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27
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Joshi AS, Nebenfuehr B, Choudhary V, Satpute-Krishnan P, Levine TP, Golden A, Prinz WA. Lipid droplet and peroxisome biogenesis occur at the same ER subdomains. Nat Commun 2018; 9:2940. [PMID: 30054481 PMCID: PMC6063926 DOI: 10.1038/s41467-018-05277-3] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 06/18/2018] [Indexed: 12/19/2022] Open
Abstract
Nascent lipid droplet (LD) formation occurs in the endoplasmic reticulum (ER) membrane but it is not known how sites of biogenesis are determined. We previously identified ER domains in S. cerevisiae containing the reticulon homology domain (RHD) protein Pex30 that are regions where preperoxisomal vesicles (PPVs) form. Here, we show that Pex30 domains are also sites where most nascent LDs form. Mature LDs usually remain associated with Pex30 subdomains, and the same Pex30 subdomain can simultaneously associate with a LD and a PPV or peroxisome. We find that in higher eukaryotes multiple C2 domain containing transmembrane protein (MCTP2) is similar to Pex30: it contains an RHD and resides in ER domains where most nascent LD biogenesis occurs and that often associate with peroxisomes. Together, these findings indicate that most LDs and PPVs form and remain associated with conserved ER subdomains, and suggest a link between LD and peroxisome biogenesis.
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Affiliation(s)
- Amit S Joshi
- National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA.
| | - Benjamin Nebenfuehr
- National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - Vineet Choudhary
- National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | | | - Tim P Levine
- University College London, Institute of Ophthalmology, London, EC1V 9EL, UK
| | - Andy Golden
- National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - William A Prinz
- National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA.
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28
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Hauswirth AG, Ford KJ, Wang T, Fetter RD, Tong A, Davis GW. A postsynaptic PI3K-cII dependent signaling controller for presynaptic homeostatic plasticity. eLife 2018; 7:31535. [PMID: 29303480 PMCID: PMC5773188 DOI: 10.7554/elife.31535] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 01/04/2018] [Indexed: 01/29/2023] Open
Abstract
Presynaptic homeostatic plasticity stabilizes information transfer at synaptic connections in organisms ranging from insect to human. By analogy with principles of engineering and control theory, the molecular implementation of PHP is thought to require postsynaptic signaling modules that encode homeostatic sensors, a set point, and a controller that regulates transsynaptic negative feedback. The molecular basis for these postsynaptic, homeostatic signaling elements remains unknown. Here, an electrophysiology-based screen of the Drosophila kinome and phosphatome defines a postsynaptic signaling platform that includes a required function for PI3K-cII, PI3K-cIII and the small GTPase Rab11 during the rapid and sustained expression of PHP. We present evidence that PI3K-cII localizes to Golgi-derived, clathrin-positive vesicles and is necessary to generate an endosomal pool of PI(3)P that recruits Rab11 to recycling endosomal membranes. A morphologically distinct subdivision of this platform concentrates postsynaptically where we propose it functions as a homeostatic controller for retrograde, trans-synaptic signaling.
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Affiliation(s)
- Anna G Hauswirth
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, United States
| | - Kevin J Ford
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, United States
| | - Tingting Wang
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, United States
| | - Richard D Fetter
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, United States
| | - Amy Tong
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, United States
| | - Graeme W Davis
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, United States
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29
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Roemmich AJ, Schutte SS, O'Dowd DK. Ex vivo Whole-cell Recordings in Adult Drosophila Brain. Bio Protoc 2018; 8:e2467. [PMID: 30148187 DOI: 10.21769/bioprotoc.2467] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Cost-effective and efficient, the fruit fly (Drosophila melanogaster) has been used to make many key discoveries in the field of neuroscience and to model a number of neurological disorders. Great strides in understanding have been made using sophisticated molecular genetic tools and behavioral assays. Functional analysis of neural activity was initially limited to the neuromuscular junction (NMJ) and in the central nervous system (CNS) of embryos and larvae. Elucidating the cellular mechanisms underlying neurological processes and disorders in the mature nervous system have been more challenging due to difficulty in recording from neurons in adult brains. To this aim we developed an ex vivo preparation in which a whole brain is isolated from the head capsule of an adult fly and placed in a recording chamber. With this preparation, whole cell recording of identified neurons in the adult brain can be combined with genetic, pharmacological and environmental manipulations to explore cellular mechanisms of neuronal function and dysfunction. It also serves as an important platform for evaluating the mechanism of action of new therapies identified through behavioral assays for treating neurological diseases. Here we present our protocol for ex vivo preparations and whole-cell recordings in the adult Drosophila brain.
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Affiliation(s)
- Alexa J Roemmich
- Department of Developmental and Cell Biology, University of California, Irvine, California, USA
| | - Soleil S Schutte
- Department of Anesthesiology, University of Florida, Gainesville, Florida, USA
| | - Diane K O'Dowd
- Department of Developmental and Cell Biology, University of California, Irvine, California, USA
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30
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The Maintenance of Synaptic Homeostasis at the Drosophila Neuromuscular Junction Is Reversible and Sensitive to High Temperature. eNeuro 2017; 4:eN-NWR-0220-17. [PMID: 29255795 PMCID: PMC5732017 DOI: 10.1523/eneuro.0220-17.2017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 11/20/2017] [Accepted: 11/23/2017] [Indexed: 11/25/2022] Open
Abstract
Homeostasis is a vital mode of biological self-regulation. The hallmarks of homeostasis for any biological system are a baseline set point of physiological activity, detection of unacceptable deviations from the set point, and effective corrective measures to counteract deviations. Homeostatic synaptic plasticity (HSP) is a form of neuroplasticity in which neurons and circuits resist environmental perturbations and stabilize levels of activity. One assumption is that if a perturbation triggers homeostatic corrective changes in neuronal properties, those corrective measures should be reversed upon removal of the perturbation. We test the reversibility and limits of HSP at the well-studied Drosophila melanogaster neuromuscular junction (NMJ). At the Drosophila NMJ, impairment of glutamate receptors causes a decrease in quantal size, which is offset by a corrective, homeostatic increase in the number of vesicles released per evoked presynaptic stimulus, or quantal content. This process has been termed presynaptic homeostatic potentiation (PHP). Taking advantage of the GAL4/GAL80TS/UAS expression system, we triggered PHP by expressing a dominant-negative glutamate receptor subunit at the NMJ. We then reversed PHP by halting expression of the dominant-negative receptor. Our data show that PHP is fully reversible over a time course of 48–72 h after the dominant-negative glutamate receptor stops being genetically expressed. As an extension of these experiments, we find that when glutamate receptors are impaired, neither PHP nor NMJ growth is reliably sustained at high culturing temperatures (30–32°C). These data suggest that a limitation of homeostatic signaling at high temperatures could stem from the synapse facing a combination of challenges simultaneously.
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31
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Extended Synaptotagmin Localizes to Presynaptic ER and Promotes Neurotransmission and Synaptic Growth in Drosophila. Genetics 2017; 207:993-1006. [PMID: 28882990 DOI: 10.1534/genetics.117.300261] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 09/01/2017] [Indexed: 01/08/2023] Open
Abstract
The endoplasmic reticulum (ER) is an extensive organelle in neurons with important roles at synapses including the regulation of cytosolic Ca2+, neurotransmission, lipid metabolism, and membrane trafficking. Despite intriguing evidence for these crucial functions, how the presynaptic ER influences synaptic physiology remains enigmatic. To gain insight into this question, we have generated and characterized mutations in the single extended synaptotagmin (Esyt) ortholog in Drosophila melanogaster Esyts are evolutionarily conserved ER proteins with Ca2+-sensing domains that have recently been shown to orchestrate membrane tethering and lipid exchange between the ER and plasma membrane. We first demonstrate that Esyt localizes to presynaptic ER structures at the neuromuscular junction. Next, we show that synaptic growth, structure, and homeostatic plasticity are surprisingly unperturbed at synapses lacking Esyt expression. However, neurotransmission is reduced in Esyt mutants, consistent with a presynaptic role in promoting neurotransmitter release. Finally, neuronal overexpression of Esyt enhances synaptic growth and the sustainment of the vesicle pool during intense activity, suggesting that increased Esyt levels may modulate the membrane trafficking and/or resting Ca2+ pathways that control synapse extension. Thus, we identify Esyt as a presynaptic ER protein that can promote neurotransmission and synaptic growth, revealing the first in vivo neuronal functions of this conserved gene family.
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