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Zhu D, Zhang J, Ma X, Hu M, Gao F, Hashem JB, Lyu J, Wei J, Cui Y, Qiu S, Chen C. Overabundant endocannabinoids in neurons are detrimental to cognitive function. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.17.613513. [PMID: 39345517 PMCID: PMC11430108 DOI: 10.1101/2024.09.17.613513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 10/01/2024]
Abstract
2-Arachidonoylglycerol (2-AG) is the most prevalent endocannabinoid involved in maintaining brain homeostasis. Previous studies have demonstrated that inactivating monoacylglycerol lipase (MAGL), the primary enzyme responsible for degrading 2-AG in the brain, alleviates neuropathology and prevents synaptic and cognitive decline in animal models of neurodegenerative diseases. However, we show that selectively inhibiting 2-AG metabolism in neurons impairs cognitive function in mice. This cognitive impairment appears to result from decreased expression of synaptic proteins and synapse numbers, impaired long-term synaptic plasticity and cortical circuit functional connectivity, and diminished neurogenesis. Interestingly, the synaptic and cognitive deficits induced by neuronal MAGL inactivation can be counterbalanced by inhibiting astrocytic 2-AG metabolism. Transcriptomic analyses reveal that inhibiting neuronal 2-AG degradation leads to widespread changes in expression of genes associated with synaptic function. These findings suggest that crosstalk in 2-AG signaling between astrocytes and neurons is crucial for maintaining synaptic and cognitive functions and that excessive 2-AG in neurons alone is detrimental to cognitive function.
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Lee E, Choi HK, Kwon Y, Lee KB. Real-Time, Non-Invasive Monitoring of Neuronal Differentiation Using Intein-Enabled Fluorescence Signal Translocation in Genetically Encoded Stem Cell-Based Biosensors. ADVANCED FUNCTIONAL MATERIALS 2024; 34:2400394. [PMID: 39308638 PMCID: PMC11412434 DOI: 10.1002/adfm.202400394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Indexed: 09/25/2024]
Abstract
Real-time and non-invasive monitoring of neuronal differentiation will help increase our understanding of neuronal development and help develop regenerative stem cell therapies for neurodegenerative diseases. Traditionally, reverse transcription-polymerase chain reaction (RT-PCR), western blotting, and immunofluorescence (IF) staining have been widely used to investigate stem cell differentiation; however, their limitations include endpoint analysis, invasive nature of monitoring, and lack of single-cell-level resolution. Several limitations hamper current approaches to studying neural stem cell (NSC) differentiation. In particular, fixation and staining procedures can introduce artificial changes in cellular morphology, hindering our ability to accurately monitor the progression of the process and fully understand its functional aspects, particularly those related to cellular connectivity and neural network formation. Herein, we report a novel approach to monitor neuronal differentiation of NSCs non-invasively in real-time using cell-based biosensors (CBBs). Our research efforts focused on utilizing intein-mediated protein engineering to design and construct a highly sensitive biosensor capable of detecting a biomarker of neuronal differentiation, hippocalcin. Hippocalcin is a critical protein involved in neurogenesis, and the CBB functions by translocating a fluorescence signal to report the presence of hippocalcin externally. To construct the hippocalcin sensor proteins, hippocalcin bioreceptors, AP2 and glutamate ionotropic receptor AMPA-type subunit 2 (GRIA2), were fused to each split-intein carrying split-nuclear localization signal (NLS) peptides, respectively, and a fluorescent protein was introduced as a reporter. Protein splicing (PS) was triggered in the presence of hippocalcin to generate functional signal peptides, which promptly translocated the fluorescence signal to the nucleus. The stem cell-based biosensor showed fluorescence signal translocation only upon neuronal differentiation. Undifferentiated stem cells or cells that had differentiated into astrocytes or oligodendrocytes did not show fluorescence signal translocation. The number of differentiated neurons was consistent with that measured by conventional IF staining. Furthermore, this approach allowed for the monitoring of neuronal differentiation at an earlier stage than that detected using conventional approaches, and the translocation of fluorescence signal was monitored before the noticeable expression of class III β-tubulin (TuJ1), an early neuronal differentiation marker. We believe that these novel CBBs offer an alternative to current techniques by capturing the dynamics of differentiation progress at the single-cell level and by providing a tool to evaluate how NSCs efficiently differentiate into specific cell types, particularly neurons.
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Affiliation(s)
- Euiyeon Lee
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
- Department of Biomedical Engineering, Dongguk University, Seoul 04620, Korea
| | - Hye Kyu Choi
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Youngeun Kwon
- Department of Biomedical Engineering, Dongguk University, Seoul 04620, Korea
| | - Ki-Bum Lee
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
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3
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Genetic Mapping of Behavioral Traits Using the Collaborative Cross Resource. Int J Mol Sci 2022; 24:ijms24010682. [PMID: 36614124 PMCID: PMC9821145 DOI: 10.3390/ijms24010682] [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: 10/19/2022] [Revised: 12/14/2022] [Accepted: 12/23/2022] [Indexed: 01/03/2023] Open
Abstract
The complicated interactions between genetic background, environment and lifestyle factors make it difficult to study the genetic basis of complex phenotypes, such as cognition and anxiety levels, in humans. However, environmental and other factors can be tightly controlled in mouse studies. The Collaborative Cross (CC) is a mouse genetic reference population whose common genetic and phenotypic diversity is on par with that of humans. Therefore, we leveraged the power of the CC to assess 52 behavioral measures associated with locomotor activity, anxiety level, learning and memory. This is the first application of the CC in novel object recognition tests, Morris water maze tasks, and fear conditioning tests. We found substantial continuous behavioral variations across the CC strains tested, and mapped six quantitative trait loci (QTLs) which influenced these traits, defining candidate genetic variants underlying these QTLs. Overall, our findings highlight the potential of the CC population in behavioral genetic research, while the identified genomic loci and genes driving the variation of relevant behavioral traits provide a foundation for further studies.
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Gundu C, Arruri VK, Yadav P, Navik U, Kumar A, Amalkar VS, Vikram A, Gaddam RR. Dynamin-Independent Mechanisms of Endocytosis and Receptor Trafficking. Cells 2022; 11:cells11162557. [PMID: 36010634 PMCID: PMC9406725 DOI: 10.3390/cells11162557] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 08/03/2022] [Accepted: 08/13/2022] [Indexed: 11/16/2022] Open
Abstract
Endocytosis is a fundamental mechanism by which cells perform housekeeping functions. It occurs via a variety of mechanisms and involves many regulatory proteins. The GTPase dynamin acts as a “molecular scissor” to form endocytic vesicles and is a critical regulator among the proteins involved in endocytosis. Some GTPases (e.g., Cdc42, arf6, RhoA), membrane proteins (e.g., flotillins, tetraspanins), and secondary messengers (e.g., calcium) mediate dynamin-independent endocytosis. These pathways may be convergent, as multiple pathways exist in a single cell. However, what determines the specific path of endocytosis is complex and challenging to comprehend. This review summarizes the mechanisms of dynamin-independent endocytosis, the involvement of microRNAs, and factors that contribute to the cellular decision about the specific route of endocytosis.
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Affiliation(s)
- Chayanika Gundu
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad 500037, Telangana, India
| | - Vijay Kumar Arruri
- Department of Neurological Surgery, University of Wisconsin, Madison, WI 53792, USA
| | - Poonam Yadav
- Department of Pharmacology, Central University of Punjab, Bathinda 151001, Punjab, India
| | - Umashanker Navik
- Department of Pharmacology, Central University of Punjab, Bathinda 151001, Punjab, India
| | - Ashutosh Kumar
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Kolkata 700054, West Bengal, India
| | - Veda Sudhir Amalkar
- Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA
| | - Ajit Vikram
- Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA
| | - Ravinder Reddy Gaddam
- Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA
- Correspondence:
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Takahashi M, Nakabayashi T, Mita N, Jin X, Aikawa Y, Sasamoto K, Miyoshi G, Miyata M, Inoue T, Ohshima T. Involvement of Cdk5 activating subunit p35 in synaptic plasticity in excitatory and inhibitory neurons. Mol Brain 2022; 15:37. [PMID: 35484559 PMCID: PMC9052517 DOI: 10.1186/s13041-022-00922-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 04/14/2022] [Indexed: 11/23/2022] Open
Abstract
Cyclin-dependent kinase 5 (Cdk5) /p35 is involved in many developmental processes of the central nervous system. Cdk5/p35 is also implicated in synaptic plasticity, learning and memory. Several lines of conditional Cdk5 knockout mice (KO) have been generated and have shown different outcomes for learning and memory. Here, we present our analysis of p35 conditional KO mice (p35cKO) in hippocampal pyramidal neurons or forebrain GABAergic neurons using electrophysiological and behavioral methods. In the fear conditioning task, CamKII-p35cKO mice showed impaired memory retention. Furthermore, NMDAR-dependent long-term depression (LTD) induction by low-frequency stimuli in hippocampal slices from CamkII-p35cKO mice was impaired compared to that in control mice. In contrast, Dlx-p35cKO mice showed no abnormalities in behavioral tasks and electrophysiological analysis in their hippocampal slices. These results indicated that Cdk5/p35 in excitatory neurons is important for the hippocampal synaptic plasticity and associative memory retention.
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Affiliation(s)
- Miyuki Takahashi
- Laboratory for Molecular Brain Science, Department of Life Science and Medical Bioscience, Waseda University, 2-2 Wakamatsu-cho, Shinjuku, Tokyo, 162-0056, Japan
| | - Takeru Nakabayashi
- Laboratory for Molecular Brain Science, Department of Life Science and Medical Bioscience, Waseda University, 2-2 Wakamatsu-cho, Shinjuku, Tokyo, 162-0056, Japan
| | - Naoki Mita
- Laboratory for Molecular Brain Science, Department of Life Science and Medical Bioscience, Waseda University, 2-2 Wakamatsu-cho, Shinjuku, Tokyo, 162-0056, Japan
| | - Xiaohua Jin
- Laboratory for Molecular Brain Science, Department of Life Science and Medical Bioscience, Waseda University, 2-2 Wakamatsu-cho, Shinjuku, Tokyo, 162-0056, Japan
| | - Yuta Aikawa
- Laboratory for Neurophysiology, Department of Life Science and Medical Bioscience, Waseda University, 2-2 Wakamatsu-cho, Shinjuku, Tokyo, 162-0056, Japan
| | - Kodai Sasamoto
- Laboratory for Molecular Brain Science, Department of Life Science and Medical Bioscience, Waseda University, 2-2 Wakamatsu-cho, Shinjuku, Tokyo, 162-0056, Japan
| | - Goichi Miyoshi
- Department of Neurophysiology, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku, Tokyo, 162-8666, Japan.,Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine, 3-39-22 Showa-cho, Maebashi, Gunma, 371-8511, Japan
| | - Mariko Miyata
- Department of Neurophysiology, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku, Tokyo, 162-8666, Japan
| | - Takafumi Inoue
- Laboratory for Neurophysiology, Department of Life Science and Medical Bioscience, Waseda University, 2-2 Wakamatsu-cho, Shinjuku, Tokyo, 162-0056, Japan
| | - Toshio Ohshima
- Laboratory for Molecular Brain Science, Department of Life Science and Medical Bioscience, Waseda University, 2-2 Wakamatsu-cho, Shinjuku, Tokyo, 162-0056, Japan.
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Xu F, Mu J, Teng Y, Zhang X, Sundaram K, Sriwastva MK, Kumar A, Lei C, Zhang L, Liu QM, Yan J, McClain CJ, Merchant ML, Zhang HG. Restoring Oat Nanoparticles Mediated Brain Memory Function of Mice Fed Alcohol by Sorting Inflammatory Dectin-1 Complex Into Microglial Exosomes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2105385. [PMID: 34897972 PMCID: PMC8858573 DOI: 10.1002/smll.202105385] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 10/25/2021] [Indexed: 05/23/2023]
Abstract
Microglia modulate pro-inflammatory and neurotoxic activities. Edible plant-derived factors improve brain function. Current knowledge of the molecular interactions between edible plant-derived factors and the microglial cell is limited. Here an alcohol-induced chronic brain inflammation model is used to identify that the microglial cell is the novel target of oat nanoparticles (oatN). Oral administration of oatN inhibits brain inflammation and improves brain memory function of mice that are fed alcohol. Mechanistically, ethanol activates dectin-1 mediated inflammatory pathway. OatN is taken up by microglial cells via β-glucan mediated binding to microglial hippocalcin (HPCA) whereas oatN digalactosyldiacylglycerol (DGDG) prevents assess of oatN β-glucan to dectin-1. Subsequently endocytosed β-glucan/HPCA is recruited in an endosomal recycling compartment (ERC) via interaction with Rab11a. This complex then sequesters the dectin-1 in the ERC in an oatN β-glucan dependent manner and alters the location of dectin-1 from Golgi to early endosomes and lysosomes and increases exportation of dectin-1 into exosomes in an Rab11a dependent manner. Collectively, these cascading actions lead to preventing the activation of the alcoholic induced brain inflammation signing pathway(s). This coordinated assembling of the HPCA/Rab11a/dectin-1 complex by oral administration of oatN may contribute to the prevention of brain inflammation.
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Affiliation(s)
- Fangyi Xu
- James Graham Brown Cancer Center, Department of Microbiology & Immunology, University of Louisville, Louisville, KY, 40202, USA
| | - Jingyao Mu
- James Graham Brown Cancer Center, Department of Microbiology & Immunology, University of Louisville, Louisville, KY, 40202, USA
| | - Yun Teng
- James Graham Brown Cancer Center, Department of Microbiology & Immunology, University of Louisville, Louisville, KY, 40202, USA
| | - Xiangcheng Zhang
- James Graham Brown Cancer Center, Department of Microbiology & Immunology, University of Louisville, Louisville, KY, 40202, USA
- Department of ICU, the Affiliated Huaian NO.1 People's Hospital of Nanjing Medical University, Huaian, Jiangsu, 223300, China
| | - Kumaran Sundaram
- James Graham Brown Cancer Center, Department of Microbiology & Immunology, University of Louisville, Louisville, KY, 40202, USA
| | - Mukesh K Sriwastva
- James Graham Brown Cancer Center, Department of Microbiology & Immunology, University of Louisville, Louisville, KY, 40202, USA
| | - Anil Kumar
- James Graham Brown Cancer Center, Department of Microbiology & Immunology, University of Louisville, Louisville, KY, 40202, USA
| | - Chao Lei
- James Graham Brown Cancer Center, Department of Microbiology & Immunology, University of Louisville, Louisville, KY, 40202, USA
| | - Lifeng Zhang
- James Graham Brown Cancer Center, Department of Microbiology & Immunology, University of Louisville, Louisville, KY, 40202, USA
| | - Qiaohong M Liu
- Peak Neuromonitoring Associates-Kentucky, Louisville, KY, 40202, USA
| | - Jun Yan
- James Graham Brown Cancer Center, Department of Microbiology & Immunology, University of Louisville, Louisville, KY, 40202, USA
| | - Craig J McClain
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Louisville, Louisville, KY, 40202, USA
| | - Michael L Merchant
- Kidney Disease Program and Clinical Proteomics Center, University of Louisville, Louisville, KY, 40202, USA
| | - Huang-Ge Zhang
- James Graham Brown Cancer Center, Department of Microbiology & Immunology, University of Louisville, Louisville, KY, 40202, USA
- Robley Rex Veterans Affairs Medical Center, Louisville, KY, 40206, USA
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7
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Sahu G, Turner RW. The Molecular Basis for the Calcium-Dependent Slow Afterhyperpolarization in CA1 Hippocampal Pyramidal Neurons. Front Physiol 2022; 12:759707. [PMID: 35002757 PMCID: PMC8730529 DOI: 10.3389/fphys.2021.759707] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 11/01/2021] [Indexed: 12/02/2022] Open
Abstract
Neuronal signal transmission depends on the frequency, pattern, and timing of spike output, each of which are shaped by spike afterhyperpolarizations (AHPs). There are classically three post-spike AHPs of increasing duration categorized as fast, medium and slow AHPs that hyperpolarize a cell over a range of 10 ms to 30 s. Intensive early work on CA1 hippocampal pyramidal cells revealed that all three AHPs incorporate activation of calcium-gated potassium channels. The ionic basis for a fAHP was rapidly attributed to the actions of big conductance (BK) and the mAHP to small conductance (SK) or Kv7 potassium channels. In stark contrast, the ionic basis for a prominent slow AHP of up to 30 s duration remained an enigma for over 30 years. Recent advances in pharmacological, molecular, and imaging tools have uncovered the expression of a calcium-gated intermediate conductance potassium channel (IK, KCa3.1) in central neurons that proves to contribute to the slow AHP in CA1 hippocampal pyramidal cells. Together the data show that the sAHP arises in part from a core tripartite complex between Cav1.3 (L-type) calcium channels, ryanodine receptors, and IK channels at endoplasmic reticulum-plasma membrane junctions. Work on the sAHP in CA1 pyramidal neurons has again quickened pace, with identified contributions by both IK channels and the Na-K pump providing answers to several mysteries in the pharmacological properties of the sAHP.
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Affiliation(s)
- Giriraj Sahu
- National Institute of Pharmaceutical Education and Research Ahmedabad, Ahmedabad, India
| | - Ray W Turner
- Department Cell Biology & Anatomy, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
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8
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Biswas D, Shenoy SV, Chetanya C, Lachén-Montes M, Barpanda A, Athithyan AP, Ghosh S, Ausín K, Zelaya MV, Fernández-Irigoyen J, Manna A, Roy S, Talukdar A, Ball GR, Santamaría E, Srivastava S. Deciphering the Interregional and Interhemisphere Proteome of the Human Brain in the Context of the Human Proteome Project. J Proteome Res 2021; 20:5280-5293. [PMID: 34714085 DOI: 10.1021/acs.jproteome.1c00511] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
This study, which performs an extensive mass spectrometry-based analysis of 19 brain regions from both left and right hemispheres, presents the first draft of the human brain interhemispheric proteome. This high-resolution proteomics data provides comprehensive coverage of 3300 experimentally measured (nonhypothetical) proteins across multiple regions, allowing the characterization of protein-centric interhemispheric differences and synapse biology, and portrays the regional mapping of specific regions for brain disorder biomarkers. In the context of the Human Proteome Project (HPP), the interhemispheric proteome data reveal specific markers like chimerin 2 (CHN2) in the cerebellar vermis, olfactory marker protein (OMP) in the olfactory bulb, and ankyrin repeat domain 63 (ANKRD63) in basal ganglia, in line with regional brain transcriptomes mapped in the Human Protein Atlas (HPA). In addition, an in silico analysis pipeline was used to predict the structure and function of the uncharacterized uPE1 protein ANKRD63, and parallel reaction monitoring (PRM) was applied to validate its region-specific expression. Finally, we have built the Interhemispheric Brain Proteome Map (IBPM) Portal (www.brainprot.org) to stimulate the scientific community's interest in the brain molecular landscape and accelerate and support research in neuroproteomics. Data are available via ProteomeXchange with identifier PXD019936.
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Affiliation(s)
- Deeptarup Biswas
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Sanjyot Vinayak Shenoy
- Department of Mathematics, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Chetanya Chetanya
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Mercedes Lachén-Montes
- Clinical Neuroproteomics Unit, Proteomics Platform, Proteored-ISCIII, Navarrabiomed, Hospital Universitario de Navarra (HUN), Universidad Pública de Navarra (UPNA), Navarra Institute for Health Research (IdiSNA), 31008 Pamplona, Spain
| | - Abhilash Barpanda
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | | | - Susmita Ghosh
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Karina Ausín
- Clinical Neuroproteomics Unit, Proteomics Platform, Proteored-ISCIII, Navarrabiomed, Hospital Universitario de Navarra (HUN), Universidad Pública de Navarra (UPNA), Navarra Institute for Health Research (IdiSNA), 31008 Pamplona, Spain
| | - María Victoria Zelaya
- Clinical Neuroproteomics Unit, Proteomics Platform, Proteored-ISCIII, Navarrabiomed, Hospital Universitario de Navarra (HUN), Universidad Pública de Navarra (UPNA), Navarra Institute for Health Research (IdiSNA), 31008 Pamplona, Spain
| | - Joaquín Fernández-Irigoyen
- Clinical Neuroproteomics Unit, Proteomics Platform, Proteored-ISCIII, Navarrabiomed, Hospital Universitario de Navarra (HUN), Universidad Pública de Navarra (UPNA), Navarra Institute for Health Research (IdiSNA), 31008 Pamplona, Spain
| | - Akash Manna
- Medicine Department, Medical College Hospital Kolkata, 88 College Street, Kolkata 700072, India
| | - Sudesh Roy
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Arunasu Talukdar
- Medicine Department, Medical College Hospital Kolkata, 88 College Street, Kolkata 700072, India
| | - Graham Roy Ball
- School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, United Kingdom
| | - Enrique Santamaría
- Clinical Neuroproteomics Unit, Proteomics Platform, Proteored-ISCIII, Navarrabiomed, Hospital Universitario de Navarra (HUN), Universidad Pública de Navarra (UPNA), Navarra Institute for Health Research (IdiSNA), 31008 Pamplona, Spain
| | - Sanjeeva Srivastava
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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9
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Siegert S, Schmidt WM, Pletschko T, Bittner RE, Gobara S, Freilinger M. Specific Cognitive Changes due to Hippocalcin Alterations? A Novel Familial Homozygous Hippocalcin Variant Associated with Inherited Dystonia and Altered Cognition. Neuropediatrics 2021; 52:377-382. [PMID: 33511595 DOI: 10.1055/s-0040-1722686] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
BACKGROUND Recent research suggested an hippocalcin (HPCA)-related form of DYT2-like autosomal recessive dystonia. Two reports highlight a broad spectrum of the clinical phenotype. Here, we describe a novel HPCA gene variant in a pediatric patient and two affected relatives. METHODS Whole exome sequencing was applied after a thorough clinical and neurological examination of the index patient and her family members. Results of neuropsychological testing were analyzed. RESULTS Whole exome sequencing revealed a novel homozygous missense variant in the HPCA gene [c.182C>T p.(Ala61Val)] in our pediatric patient and the two affected family members. Clinically, the cases presented with dystonia, dysarthria, and jerky movements. We observed a particular cognitive profile with executive dysfunctions in our patient, which corresponds to the cognitive deficits that have been observed in the patients previously described. CONCLUSION We present a novel genetic variant of the HPCA gene associated with autosomal recessive dystonia in a child with childhood-onset dystonia supporting its clinical features. Furthermore, we propose specific HPCA-related cognitive changes in homozygous carriers, underlining the importance of undertaking a systematic assessment of cognition in HPCA-related dystonia.
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Affiliation(s)
- Sandy Siegert
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Austria
| | - Wolfgang M Schmidt
- Neuromuscular Research Department, Medical University of Vienna, Austria
| | - Thomas Pletschko
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Austria
| | - Reginald E Bittner
- Neuromuscular Research Department, Medical University of Vienna, Austria
| | - Sonja Gobara
- Ambulatorium Sonnenschein, Sozialpädiatrisches Zentrum, St. Pölten, Austria
| | - Michael Freilinger
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Austria
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10
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Martin EE, Wleklinski E, Hoang HTM, Ahmad M. Interaction and Subcellular Association of PRRT1/SynDIG4 With AMPA Receptors. Front Synaptic Neurosci 2021; 13:705664. [PMID: 34408636 PMCID: PMC8365426 DOI: 10.3389/fnsyn.2021.705664] [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] [Received: 05/05/2021] [Accepted: 07/05/2021] [Indexed: 11/13/2022] Open
Abstract
AMPA receptors (AMPAR) are organized into supramolecular complexes in association with other membrane proteins that provide exquisite regulation of their biophysical properties and subcellular trafficking. Proline-rich transmembrane protein 1 (PRRT1), also named as SynDIG4, is a component of native AMPAR complexes in multiple brain regions. Deletion of PRRT1 leads to altered surface levels and phosphorylation status of AMPARs, as well as impaired forms of synaptic plasticity. Here, we have investigated the mechanisms underlying the observed regulation of AMPARs by investigating the interaction properties and subcellular localization of PRRT1. Our results show that PRRT1 can interact physically with all AMPAR subunits GluA1-GluA4. We decipher the membrane topology of PRRT1 to find that contrary to the predicted dual membrane pass, only the second hydrophobic segment spans the membrane completely, and is involved in mediating the interaction with AMPARs. We also report a physical interaction of PRRT1 with phosphatase PP2B that dephosphorylates AMPARs during synaptic plasticity. Our co-localization analysis in primary neuronal cultures identifies that PRRT1 associates with AMPARs extrasynaptically where it localizes to early and recycling endosomes as well as to the plasma membrane. These findings advance the understanding of the mechanisms by which PRRT1 regulates AMPARs under basal conditions and during synaptic plasticity.
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Affiliation(s)
- Emily Eischen Martin
- Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Erica Wleklinski
- Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Hanh T M Hoang
- Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Mohiuddin Ahmad
- Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
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11
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Williams JB, Cao Q, Yan Z. Transcriptomic analysis of human brains with Alzheimer's disease reveals the altered expression of synaptic genes linked to cognitive deficits. Brain Commun 2021; 3:fcab123. [PMID: 34423299 PMCID: PMC8374979 DOI: 10.1093/braincomms/fcab123] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 03/30/2021] [Accepted: 04/22/2021] [Indexed: 11/14/2022] Open
Abstract
Alzheimer's disease is a progressive neurodegenerative disorder associated with memory loss and impaired executive function. The molecular underpinnings causing cognitive deficits in Alzheimer's disease are loosely understood. Here, we performed cross-study large-scale transcriptomic analyses of postmortem prefrontal cortex derived from Alzheimer's disease patients to reveal the role of aberrant gene expression in this disease. We identified that one of the most prominent changes in prefrontal cortex of Alzheimer's disease humans was the downregulation of genes in excitatory and inhibitory neurons that are associated with synaptic functions, particularly the SNARE-binding complex, which is essential for vesicle docking and neurotransmitter release. Comparing genomic data of Alzheimer's disease with proteomic data of cognitive trajectory, we found that many of the lost synaptic genes in Alzheimer's disease encode hub proteins whose increased abundance is required for cognitive stability. This study has revealed potential molecular targets for therapeutic intervention of cognitive decline associated with Alzheimer's disease.
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Affiliation(s)
- Jamal B Williams
- Department of Physiology and Biophysics, State University of New York at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
| | - Qing Cao
- Department of Physiology and Biophysics, State University of New York at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
| | - Zhen Yan
- Department of Physiology and Biophysics, State University of New York at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
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12
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Kelemen K, Szilágyi T. New Approach for Untangling the Role of Uncommon Calcium-Binding Proteins in the Central Nervous System. Brain Sci 2021. [PMID: 34069107 DOI: 10.3390/brainsci11050634ht] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023] Open
Abstract
Although Ca2+ ion plays an essential role in cellular physiology, calcium-binding proteins (CaBPs) were long used for mainly as immunohistochemical markers of specific cell types in different regions of the central nervous system. They are a heterogeneous and wide-ranging group of proteins. Their function was studied intensively in the last two decades and a tremendous amount of information was gathered about them. Girard et al. compiled a comprehensive list of the gene-expression profiles of the entire EF-hand gene superfamily in the murine brain. We selected from this database those CaBPs which are related to information processing and/or neuronal signalling, have a Ca2+-buffer activity, Ca2+-sensor activity, modulator of Ca2+-channel activity, or a yet unknown function. In this way we created a gene function-based selection of the CaBPs. We cross-referenced these findings with publicly available, high-quality RNA-sequencing and in situ hybridization databases (Human Protein Atlas (HPA), Brain RNA-seq database and Allen Brain Atlas integrated into the HPA) and created gene expression heat maps of the regional and cell type-specific expression levels of the selected CaBPs. This represents a useful tool to predict and investigate different expression patterns and functions of the less-known CaBPs of the central nervous system.
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Affiliation(s)
- Krisztina Kelemen
- Department of Physiology, Doctoral School, Faculty of Medicine, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 540142 Târgu Mureș, Romania
| | - Tibor Szilágyi
- Department of Physiology, Doctoral School, Faculty of Medicine, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 540142 Târgu Mureș, Romania
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13
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Kelemen K, Szilágyi T. New Approach for Untangling the Role of Uncommon Calcium-Binding Proteins in the Central Nervous System. Brain Sci 2021; 11:brainsci11050634. [PMID: 34069107 PMCID: PMC8156796 DOI: 10.3390/brainsci11050634] [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: 04/14/2021] [Revised: 05/09/2021] [Accepted: 05/10/2021] [Indexed: 02/07/2023] Open
Abstract
Although Ca2+ ion plays an essential role in cellular physiology, calcium-binding proteins (CaBPs) were long used for mainly as immunohistochemical markers of specific cell types in different regions of the central nervous system. They are a heterogeneous and wide-ranging group of proteins. Their function was studied intensively in the last two decades and a tremendous amount of information was gathered about them. Girard et al. compiled a comprehensive list of the gene-expression profiles of the entire EF-hand gene superfamily in the murine brain. We selected from this database those CaBPs which are related to information processing and/or neuronal signalling, have a Ca2+-buffer activity, Ca2+-sensor activity, modulator of Ca2+-channel activity, or a yet unknown function. In this way we created a gene function-based selection of the CaBPs. We cross-referenced these findings with publicly available, high-quality RNA-sequencing and in situ hybridization databases (Human Protein Atlas (HPA), Brain RNA-seq database and Allen Brain Atlas integrated into the HPA) and created gene expression heat maps of the regional and cell type-specific expression levels of the selected CaBPs. This represents a useful tool to predict and investigate different expression patterns and functions of the less-known CaBPs of the central nervous system.
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14
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Santa-Marinha L, Castanho I, Silva RR, Bravo FV, Miranda AM, Meira T, Morais-Ribeiro R, Marques F, Xu Y, Point du Jour K, Wenk M, Chan RB, Di Paolo G, Pinto V, Oliveira TG. Phospholipase D1 Ablation Disrupts Mouse Longitudinal Hippocampal Axis Organization and Functioning. Cell Rep 2021; 30:4197-4208.e6. [PMID: 32209478 DOI: 10.1016/j.celrep.2020.02.102] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 01/29/2020] [Accepted: 02/27/2020] [Indexed: 01/01/2023] Open
Abstract
Phosphatidic acid (PA) is a signaling lipid involved in the modulation of synaptic structure and functioning. Based on previous work showing a decreasing PA gradient along the longitudinal axis of the rodent hippocampus, we asked whether the dorsal hippocampus (DH) and the ventral hippocampus (VH) are differentially affected by PA modulation. Here, we show that phospholipase D1 (PLD1) is a major hippocampal PA source, compared to PLD2, and that PLD1 ablation affects predominantly the lipidome of the DH. Moreover, Pld1 knockout (KO) mice show specific deficits in novel object recognition and social interaction and disruption in the DH-VH dendritic arborization differentiation in CA1/CA3 pyramidal neurons. Also, Pld1 KO animals present reduced long-term depression (LTD) induction and reduced GluN2A and SNAP-25 protein levels in the DH. Overall, we observe that PLD1-derived PA reduction leads to differential lipid signatures along the longitudinal hippocampal axis, predominantly affecting DH organization and functioning.
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Affiliation(s)
- Luísa Santa-Marinha
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Isabel Castanho
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Rita Ribeiro Silva
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Francisca Vaz Bravo
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - André Miguel Miranda
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Torcato Meira
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Rafaela Morais-Ribeiro
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Fernanda Marques
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Yimeng Xu
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA
| | - Kimberly Point du Jour
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA; Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY 10032, USA
| | - Markus Wenk
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117596, Singapore
| | - Robin Barry Chan
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA; Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY 10032, USA
| | - Gilbert Di Paolo
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA; Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY 10032, USA
| | - Vítor Pinto
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Tiago Gil Oliveira
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
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15
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The transcriptome of anterior regeneration in earthworm Eudrilus eugeniae. Mol Biol Rep 2020; 48:259-283. [PMID: 33306150 DOI: 10.1007/s11033-020-06044-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 11/28/2020] [Indexed: 12/25/2022]
Abstract
The oligochaete earthworm, Eudrilus eugeniae is capable of regenerating both anterior and posterior segments. The present study focuses on the transcriptome analysis of earthworm E. eugeniae to identify and functionally annotate the key genes supporting the anterior blastema formation and regulating the anterior regeneration of the worm. The Illumina sequencing generated a total of 91,593,182 raw reads which were assembled into 105,193 contigs using CLC genomics workbench. In total, 40,946 contigs were annotated against the NCBI nr and SwissProt database and among them, 15,702 contigs were assigned to 14,575 GO terms. Besides a total of 9389 contigs were mapped to 416 KEGG biological pathways. The RNA-Seq comparison study identified 10,868 differentially expressed genes (DEGs) and of them, 3986 genes were significantly upregulated in the anterior regenerated blastema tissue samples of the worm. The GO enrichment analysis showed angiogenesis and unfolded protein binding as the top enriched functions and the pathway enrichment analysis denoted TCA cycle as the most significantly enriched pathway associated with the upregulated gene dataset of the worm. The identified DEGs and their function and pathway information can be effectively utilized further to interpret the key cellular, genetic and molecular events associated with the regeneration of the worm.
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16
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Yang M, Luo CH, Zhu YQ, Liu YC, An YJ, Iqbal J, Wang ZZ, Ma XM. 7, 8-Dihydroxy-4-methylcoumarin reverses depression model-induced depression-like behaviors and alteration of dendritic spines in the mood circuits. Psychoneuroendocrinology 2020; 119:104767. [PMID: 32563935 DOI: 10.1016/j.psyneuen.2020.104767] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 05/05/2020] [Accepted: 06/05/2020] [Indexed: 12/12/2022]
Abstract
Major depressive disorder (MDD) is a common mental disorder characterized by a persistent feeling of sadness, slow thought, impaired focus and loss of interest but the underlying mechanisms are largely unknown. Dendritic spines play an important role in the formation and maintenance of emotional circuits in the brain. Abnormalities in this process can lead to psychiatric diseases. 7,8-Dihydroxy-4-methylcoumarin (Dhmc), a precursor in the synthesis of derivatives of 4-methyl coumarin, plays an important role in protecting the nervous system from developing diseases and its most distinctive feature is safety. The aim of this study was to investigate whether Dhmc alleviates chronic unpredictable mild stress (CUMS)-induced depression-like behaviors and reverses CUMS-induced alterations in dendritic spines of principal neurons in brain areas of the emotional circuits including the hippocampus, medial prefrontal cortex (mPFC), nucleus accumbens (NAc) and basolateral amygdala (BLA) in male rats. Our results showed that CUMS-induced depression-like behaviors were accompanied by a decrease in spine density in pyramidal neurons of both the hippocampal CA3 area and the mPFC, and an increase in spine density in both the neurons of BLA and the medium spiny neurons (MSNs) of the NAc, as well as a decrease in the levels of the AMPA receptor subunit GluA1 and Kalirin-7 in the hippocampus compared with the control group. Intraperitoneal injection (i.p.) of Dhmc to the CUMS-exposed rats ameliorated CUMS-induced depression-like behaviors and reversed CUMS-mediated alterations in spine density and the levels of both GluA1 and Kalirin-7. Our results show an important role of Dhmc in reversing CUMS-induced depression-like behaviors and CUMS-mediated alterations in spine density.
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Affiliation(s)
- Mi Yang
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Chinese Crude Drugs in Northwest China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, 710062, China; Yangling Vocational & Technical College, Yangling, 71210, China
| | - Chang-Hao Luo
- Yangling Vocational & Technical College, Yangling, 71210, China
| | - Ying-Qi Zhu
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Chinese Crude Drugs in Northwest China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, 710062, China
| | - Yuan-Chu Liu
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Chinese Crude Drugs in Northwest China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, 710062, China
| | - Ye-Juan An
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Chinese Crude Drugs in Northwest China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, 710062, China
| | - Javed Iqbal
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Chinese Crude Drugs in Northwest China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, 710062, China
| | - Zhe-Zhi Wang
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Chinese Crude Drugs in Northwest China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, 710062, China.
| | - Xin-Ming Ma
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Chinese Crude Drugs in Northwest China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, 710062, China; Department of Neuroscience, University of Connecticut Health, Farmington, CT 06030, United States.
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17
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Mondragón-Rodríguez S, Salgado-Burgos H, Peña-Ortega F. Circuitry and Synaptic Dysfunction in Alzheimer's Disease: A New Tau Hypothesis. Neural Plast 2020; 2020:2960343. [PMID: 32952546 PMCID: PMC7481966 DOI: 10.1155/2020/2960343] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 07/20/2020] [Accepted: 08/06/2020] [Indexed: 02/07/2023] Open
Abstract
For more than five decades, the field of Alzheimer's disease (AD) has focused on two main hypotheses positing amyloid-beta (Aβ) and Tau phosphorylation (pTau) as key pathogenic mediators. In line with these canonical hypotheses, several groups around the world have shown that the synaptotoxicity in AD depends mainly on the increase in pTau levels. Confronting this leading hypothesis, a few years ago, we reported that the increase in phosphorylation levels of dendritic Tau, at its microtubule domain (MD), acts as a neuroprotective mechanism that prevents N-methyl-D-aspartate receptor (NMDAr) overexcitation, which allowed us to propose that Tau protein phosphorylated near MD sites is involved in neuroprotection, rather than in neurodegeneration. Further supporting this alternative role of pTau, we have recently shown that early increases in pTau close to MD sites prevent hippocampal circuit overexcitation in a transgenic AD mouse model. Here, we will synthesize this new evidence that confronts the leading Tau-based AD hypothesis and discuss the role of pTau modulating neural circuits and network connectivity. Additionally, we will briefly address the role of brain circuit alterations as a potential biomarker for detecting the prodromal AD stage.
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Affiliation(s)
- Siddhartha Mondragón-Rodríguez
- CONACYT National Council for Science and Technology, México, Mexico
- UNAM Developmental Neurobiology and Neurophysiology, Institute of Neurobiology, National Autonomous University of México, Querétaro, Mexico
| | - Humberto Salgado-Burgos
- UADY Neurosciences Department, Autonomous University of Yucatán, 97000 Mérida, Yucatán, Mexico
| | - Fernando Peña-Ortega
- UNAM Developmental Neurobiology and Neurophysiology, Institute of Neurobiology, National Autonomous University of México, Querétaro, Mexico
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18
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Germann UA, Alam JJ. P38α MAPK Signaling-A Robust Therapeutic Target for Rab5-Mediated Neurodegenerative Disease. Int J Mol Sci 2020; 21:E5485. [PMID: 32751991 PMCID: PMC7432772 DOI: 10.3390/ijms21155485] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/25/2020] [Accepted: 07/30/2020] [Indexed: 12/11/2022] Open
Abstract
Multifactorial pathologies, involving one or more aggregated protein(s) and neuroinflammation are common in major neurodegenerative diseases, such as Alzheimer's disease and dementia with Lewy bodies. This complexity of multiple pathogenic drivers is one potential explanation for the lack of success or, at best, the partial therapeutic effects, respectively, with approaches that have targeted one specific driver, e.g., amyloid-beta, in Alzheimer's disease. Since the endosome-associated protein Rab5 appears to be a convergence point for many, if not all the most prominent pathogenic drivers, it has emerged as a major therapeutic target for neurodegenerative disease. Further, since the alpha isoform of p38 mitogen-activated protein kinase (p38α) is a major regulator of Rab5 activity and its effectors, a biology that is distinct from the classical nuclear targets of p38 signaling, brain-penetrant selective p38α kinase inhibitors provide the opportunity for significant therapeutic advances in neurogenerative disease through normalizing dysregulated Rab5 activity. In this review, we provide a brief summary of the role of Rab5 in the cell and its association with neurodegenerative disease pathogenesis. We then discuss the connection between Rab5 and p38α and summarize the evidence that through modulating Rab5 activity there are therapeutic opportunities in neurodegenerative diseases for p38α kinase inhibitors.
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19
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Sheremet YE, Olifirov B, Okhrimenko A, Cherkas V, Bagatskaya O, Belan P. Hippocalcin Distribution between the Cytosol and Plasma Membrane of Living Cells. NEUROPHYSIOLOGY+ 2020. [DOI: 10.1007/s11062-020-09845-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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20
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Cheyne JE, Montgomery JM. The cellular and molecular basis of in vivo synaptic plasticity in rodents. Am J Physiol Cell Physiol 2020; 318:C1264-C1283. [PMID: 32320288 DOI: 10.1152/ajpcell.00416.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Plasticity within the neuronal networks of the brain underlies the ability to learn and retain new information. The initial discovery of synaptic plasticity occurred by measuring synaptic strength in vivo, applying external stimulation and observing an increase in synaptic strength termed long-term potentiation (LTP). Many of the molecular pathways involved in LTP and other forms of synaptic plasticity were subsequently uncovered in vitro. Over the last few decades, technological advances in recording and imaging in live animals have seen many of these molecular mechanisms confirmed in vivo, including structural changes both pre- and postsynaptically, changes in synaptic strength, and changes in neuronal excitability. A well-studied aspect of neuronal plasticity is the capacity of the brain to adapt to its environment, gained by comparing the brains of deprived and experienced animals in vivo, and in direct response to sensory stimuli. Multiple in vivo studies have also strongly linked plastic changes to memory by interfering with the expression of plasticity and by manipulating memory engrams. Plasticity in vivo also occurs in the absence of any form of external stimulation, i.e., during spontaneous network activity occurring with brain development. However, there is still much to learn about how plasticity is induced during natural learning and how this is altered in neurological disorders.
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Affiliation(s)
- Juliette E Cheyne
- Department of Physiology and Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Johanna M Montgomery
- Department of Physiology and Centre for Brain Research, University of Auckland, Auckland, New Zealand
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21
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Abstract
Synaptic plasticity is a fundamental property of neurons referring to the activity-dependent changes in the strength and efficacy of synaptic transmission at preexisting synapses. Such changes can last from milliseconds to hours, days, or even longer and are involved in learning and memory as well as in development and response of the brain to injuries. Several types of synaptic plasticity have been described across neuronal types, brain regions, and species, but all of them share in one way or another capital importance of Ca2+-mediated processes. In this chapter, we will focus on the Ca2+-dependent events necessary for the induction and expression of multiple forms of synaptic plasticity.
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22
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Perturbed Ca2+-dependent signaling of DYT2 hippocalcin mutant as mechanism of autosomal recessive dystonia. Neurobiol Dis 2019; 132:104529. [DOI: 10.1016/j.nbd.2019.104529] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 06/22/2019] [Accepted: 07/09/2019] [Indexed: 11/23/2022] Open
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23
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Kang MJ, Park SY, Han JS. MicroRNA-24-3p regulates neuronal differentiation by controlling hippocalcin expression. Cell Mol Life Sci 2019; 76:4569-4580. [PMID: 31486848 PMCID: PMC6841749 DOI: 10.1007/s00018-019-03290-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Revised: 08/12/2019] [Accepted: 08/28/2019] [Indexed: 12/13/2022]
Abstract
Hippocalcin (HPCA) is a neuron-specific calcium-binding protein predominantly expressed in the nervous system. In the present study, we demonstrate that HPCA regulates neuronal differentiation in SH-SY5Y cells. We observed that the expression level of HPCA was increased during neuronal differentiation. Depletion of HPCA inhibited both neurite outgrowth and synaptophysin (SYP) expression, whereas overexpression of HPCA enhanced neuronal differentiation. Interestingly, we also found that the expression of HPCA mRNA was modulated by miR-24-3p. Using a dual-luciferase assay, we showed that co-transfection of a plasmid containing the miR-24-3p binding site from the 3'-untranslated region (3'UTR) of the HPCA gene and an miR-24-3p mimic effectively reduced luminescence activity. This effect was abolished when miR-24-3p seed sequences in the 3'UTR of the HPCA gene were mutated. miR-24-3p expression was decreased during differentiation, suggesting that the decreased expression level of miR-24-3p might have upregulated mRNA expression of HPCA. As expected, upregulation of miR-24-3p by an miRNA mimic led to reduced HPCA expression, accompanied by diminished neuronal differentiation. In contrast, downregulation of miR-24-3p by an antisense inhibitor promoted neurite outgrowth as well as levels of SYP expression. Taken together, these results suggest that miR-24-3p is an important miRNA that regulates neuronal differentiation by controlling HPCA expression.
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Affiliation(s)
- Min-Jeong Kang
- Department of Biomedical Sciences, Graduate School for Biomedical Science and Engineering, Hanyang University, Seoul, Republic of Korea
| | - Shin-Young Park
- Biomedical Research Institute, Department of Biochemistry and Molecular Biology, College of Medicine, Hanyang University, Seoul, Republic of Korea.
| | - Joong-Soo Han
- Department of Biomedical Sciences, Graduate School for Biomedical Science and Engineering, Hanyang University, Seoul, Republic of Korea.
- Biomedical Research Institute, Department of Biochemistry and Molecular Biology, College of Medicine, Hanyang University, Seoul, Republic of Korea.
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24
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Suppression of Alzheimer's Disease-Like Pathology Progression by Mitochondria-Targeted Antioxidant SkQ1: A Transcriptome Profiling Study. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:3984906. [PMID: 31396299 PMCID: PMC6664545 DOI: 10.1155/2019/3984906] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 05/02/2019] [Accepted: 06/02/2019] [Indexed: 01/08/2023]
Abstract
Alzheimer's disease (AD) is the most common type of dementia, with increasing prevalence and no disease-modifying treatment available yet. There is increasing evidence—from interventions targeting mitochondria—that may shed some light on new strategies for the treatment of AD. Previously, using senescence-accelerated OXYS rats that simulate key characteristics of sporadic AD, we have shown that treatment with mitochondria-targeted antioxidant SkQ1 (plastoquinonyl-decyltriphenylphosphonium) from age 12 to 18 months (that is, during active progression of AD-like pathology)—via improvement of mitochondrial function—prevented the neuronal loss and synaptic damage, enhanced neurotrophic supply, and decreased amyloid-β1–42 protein levels and tau hyperphosphorylation in the hippocampus. In the present study, we continued to explore the mechanisms of the anti-AD effects of SkQ1 in an OXYS rat model through deep RNA sequencing (RNA-seq) and focused upon the cell-specific gene expression alterations in the hippocampus. According to RNA-seq results, OXYS rats had 1,159 differentially expressed genes (DEGs) relative to Wistar rats (control), and 6-month treatment with SkQ1 decreased their number twofold. We found that 10.5% of all DEGs in untreated (control) OXYS rats were associated with mitochondrial function, whereas SkQ1 eliminated differences in the expression of 76% of DEGs (93 from 122 genes). Using transcriptome approaches, we found that the anti-AD effects of SkQ1 are associated with an improvement of the activity of many signaling pathways and intracellular processes. SkQ1 changed the expression of genes in neuronal, glial, and endothelial cells, and these genes are related to mitochondrial function, neurotrophic and synaptic activity, calcium processes, immune and cerebrovascular systems, catabolism, degradation, and apoptosis. Thus, RNA-seq analysis yields a detailed picture of transcriptional changes during the development of AD-like pathology and can point to the molecular and genetic mechanisms of action of the agents (including SkQ1) holding promise for the prevention and treatment of AD.
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25
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Burgoyne RD, Helassa N, McCue HV, Haynes LP. Calcium Sensors in Neuronal Function and Dysfunction. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a035154. [PMID: 30833454 DOI: 10.1101/cshperspect.a035154] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Calcium signaling in neurons as in other cell types can lead to varied changes in cellular function. Neuronal Ca2+ signaling processes have also become adapted to modulate the function of specific pathways over a wide variety of time domains and these can have effects on, for example, axon outgrowth, neuronal survival, and changes in synaptic strength. Ca2+ also plays a key role in synapses as the trigger for fast neurotransmitter release. Given its physiological importance, abnormalities in neuronal Ca2+ signaling potentially underlie many different neurological and neurodegenerative diseases. The mechanisms by which changes in intracellular Ca2+ concentration in neurons can bring about diverse responses is underpinned by the roles of ubiquitous or specialized neuronal Ca2+ sensors. It has been established that synaptotagmins have key functions in neurotransmitter release, and, in addition to calmodulin, other families of EF-hand-containing neuronal Ca2+ sensors, including the neuronal calcium sensor (NCS) and the calcium-binding protein (CaBP) families, play important physiological roles in neuronal Ca2+ signaling. It has become increasingly apparent that these various Ca2+ sensors may also be crucial for aspects of neuronal dysfunction and disease either indirectly or directly as a direct consequence of genetic variation or mutations. An understanding of the molecular basis for the regulation of the targets of the Ca2+ sensors and the physiological roles of each protein in identified neurons may contribute to future approaches to the development of treatments for a variety of human neuronal disorders.
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Affiliation(s)
- Robert D Burgoyne
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Nordine Helassa
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Hannah V McCue
- Centre for Genomic Research, University of Liverpool, Liverpool, United Kingdom
| | - Lee P Haynes
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
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Balint B, Charlesworth G, Erro R, Wood NW, Bhatia KP. Delineating the phenotype of autosomal-recessive HPCA mutations: Not only isolated dystonia! Mov Disord 2019; 34:589-592. [DOI: 10.1002/mds.27638] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 11/14/2018] [Indexed: 11/09/2022] Open
Affiliation(s)
- Bettina Balint
- Department of Motor Neuroscience and Movement Disorders; UCL Queen Square Institute of Neurology; London United Kingdom
- Department of Neurology; University Hospital Heidelberg; Germany
| | | | - Roberto Erro
- Center for Neurodegenerative Diseases (CEMAND), Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”; University of Salerno; Baronissi (SA) Italy
| | - Nicholas W. Wood
- Department of Molecular Neuroscience; Institute of Neurology, University College London; London United Kingdom
| | - Kailash P. Bhatia
- Department of Motor Neuroscience and Movement Disorders; UCL Queen Square Institute of Neurology; London United Kingdom
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27
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Chen KF, Lowe S, Lamaze A, Krätschmer P, Jepson J. Neurocalcin regulates nighttime sleep and arousal in Drosophila. eLife 2019; 8:e38114. [PMID: 30865587 PMCID: PMC6415939 DOI: 10.7554/elife.38114] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 01/29/2019] [Indexed: 01/28/2023] Open
Abstract
Sleep-like states in diverse organisms can be separated into distinct stages, each with a characteristic arousal threshold. However, the molecular pathways underlying different sleep stages remain unclear. The fruit fly, Drosophila melanogaster, exhibits consolidated sleep during both day and night, with night sleep associated with higher arousal thresholds compared to day sleep. Here we identify a role for the neuronal calcium sensor protein Neurocalcin (NCA) in promoting sleep during the night but not the day by suppressing nocturnal arousal and hyperactivity. We show that both circadian and light-sensing pathways define the temporal window in which NCA promotes sleep. Furthermore, we find that NCA promotes sleep by suppressing synaptic release from a dispersed wake-promoting neural network and demonstrate that the mushroom bodies, a sleep-regulatory center, are a module within this network. Our results advance the understanding of how sleep stages are genetically defined.
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Affiliation(s)
- Ko-Fan Chen
- Department of Clinical and Experimental EpilepsyUCL Institute of NeurologyLondonUnited Kingdom
| | - Simon Lowe
- Department of Clinical and Experimental EpilepsyUCL Institute of NeurologyLondonUnited Kingdom
| | - Angélique Lamaze
- Department of Clinical and Experimental EpilepsyUCL Institute of NeurologyLondonUnited Kingdom
| | - Patrick Krätschmer
- Department of Clinical and Experimental EpilepsyUCL Institute of NeurologyLondonUnited Kingdom
| | - James Jepson
- Department of Clinical and Experimental EpilepsyUCL Institute of NeurologyLondonUnited Kingdom
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28
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Key J, Mueller AK, Gispert S, Matschke L, Wittig I, Corti O, Münch C, Decher N, Auburger G. Ubiquitylome profiling of Parkin-null brain reveals dysregulation of calcium homeostasis factors ATP1A2, Hippocalcin and GNA11, reflected by altered firing of noradrenergic neurons. Neurobiol Dis 2019; 127:114-130. [PMID: 30763678 DOI: 10.1016/j.nbd.2019.02.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/05/2018] [Accepted: 02/08/2019] [Indexed: 02/06/2023] Open
Abstract
Parkinson's disease (PD) is the second most frequent neurodegenerative disorder in the old population. Among its monogenic variants, a frequent cause is a mutation in the Parkin gene (Prkn). Deficient function of Parkin triggers ubiquitous mitochondrial dysfunction and inflammation in the brain, but it remains unclear how selective neural circuits become vulnerable and finally undergo atrophy. We attempted to go beyond previous work, mostly done in peripheral tumor cells, which identified protein targets of Parkin activity, an ubiquitin E3 ligase. Thus, we now used aged Parkin-knockout (KO) mouse brain for a global quantification of ubiquitylated peptides by mass spectrometry (MS). This approach confirmed the most abundant substrate to be VDAC3, a mitochondrial outer membrane porin that modulates calcium flux, while uncovering also >3-fold dysregulations for neuron-specific factors. Ubiquitylation decreases were prominent for Hippocalcin (HPCA), Calmodulin (CALM1/CALML3), Pyruvate Kinase (PKM2), sodium/potassium-transporting ATPases (ATP1A1/2/3/4), the Rab27A-GTPase activating protein alpha (TBC1D10A) and an ubiquitin ligase adapter (DDB1), while strong increases occurred for calcium transporter ATP2C1 and G-protein subunits G(i)/G(o)/G(Tr). Quantitative immunoblots validated elevated abundance for the electrogenic pump ATP1A2, for HPCA as neuron-specific calcium sensor, which stimulates guanylate cyclases and modifies axonal slow afterhyperpolarization (sAHP), and for the calcium-sensing G-protein GNA11. We assessed if compensatory molecular regulations become insufficient over time, leading to functional deficits. Patch clamp experiments in acute Parkin-KO brain slices indeed revealed alterations of the electrophysiological properties in aged noradrenergic locus coeruleus (LC) neurons. LC neurons of aged Parkin-KO brain showed an acceleration of the spontaneous pacemaker frequency, a reduction in sAHP and shortening of action potential duration, without modulation of KCNQ potassium currents. These findings indicate altered calcium-dependent excitability in a PARK2 model of PD, mediated by diminished turnover of potential Parkin targets such as ATP1A2 and HPCA. The data also identified further novel Parkin substrate candidates like SIRT2, OTUD7B and CUL5. Our elucidation of neuron-specific mechanisms of PD pathogenesis helps to explain the known exceptional susceptibility of noradrenergic and dopaminergic projections to alterations of calcium homeostasis and its mitochondrial buffering.
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Affiliation(s)
- J Key
- Exp. Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - A K Mueller
- Institute for Physiology and Pathophysiology, Vegetative Physiology and Marburg Center for Mind, Brain and Behavior - MCMBB; Clinic for Neurology, Philipps-University Marburg, 35037 Marburg, Germany
| | - S Gispert
- Exp. Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - L Matschke
- Institute for Physiology and Pathophysiology, Vegetative Physiology and Marburg Center for Mind, Brain and Behavior - MCMBB; Clinic for Neurology, Philipps-University Marburg, 35037 Marburg, Germany
| | - I Wittig
- Functional Proteomics, SFB 815 Core Unit, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - O Corti
- Institut du Cerveau et de la Moelle épinière, ICM, Paris, F-75013, France; Inserm, U1127, Paris, F-75013, France; CNRS, UMR 7225, Paris, F-75013, France; Sorbonne Universités, Paris, F-75013, France
| | - C Münch
- Institute of Biochemistry II, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - N Decher
- Institute for Physiology and Pathophysiology, Vegetative Physiology and Marburg Center for Mind, Brain and Behavior - MCMBB; Clinic for Neurology, Philipps-University Marburg, 35037 Marburg, Germany.
| | - G Auburger
- Exp. Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany.
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29
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Hanley JG. The Regulation of AMPA Receptor Endocytosis by Dynamic Protein-Protein Interactions. Front Cell Neurosci 2018; 12:362. [PMID: 30364226 PMCID: PMC6193100 DOI: 10.3389/fncel.2018.00362] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 09/25/2018] [Indexed: 11/13/2022] Open
Abstract
The precise regulation of AMPA receptor (AMPAR) trafficking in neurons is crucial for excitatory neurotransmission, synaptic plasticity and the consequent formation and modification of neural circuits during brain development and learning. Clathrin-mediated endocytosis (CME) is an essential trafficking event for the activity-dependent removal of AMPARs from the neuronal plasma membrane, resulting in a reduction in synaptic strength known as long-term depression (LTD). The regulated AMPAR endocytosis that underlies LTD is caused by specific modes of synaptic activity, most notably stimulation of NMDA receptors (NMDARs) and metabotropic glutamate receptors (mGluRs). Numerous proteins associate with AMPAR subunits, directly or indirectly, to control their trafficking, and therefore the regulation of these protein-protein interactions in response to NMDAR or mGluR signaling is a critical feature of synaptic plasticity. This article reviews the protein-protein interactions that are dynamically regulated during synaptic plasticity to modulate AMPAR endocytosis, focussing on AMPAR binding proteins and proteins that bind the core endocytic machinery. In addition, the mechanisms for the regulation of protein-protein interactions are considered, as well as the functional consequences of these dynamic interactions on AMPAR endocytosis.
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Affiliation(s)
- Jonathan G Hanley
- Centre for Synaptic Plasticity and School of Biochemistry, University of Bristol, Bristol, United Kingdom
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30
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Yang T, Britt JK, Cintrón-Pérez CJ, Vázquez-Rosa E, Tobin KV, Stalker G, Hardie J, Taugher RJ, Wemmie J, Pieper AA, Lee A. Ca 2+-Binding Protein 1 Regulates Hippocampal-dependent Memory and Synaptic Plasticity. Neuroscience 2018; 380:90-102. [PMID: 29660444 DOI: 10.1016/j.neuroscience.2018.04.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 03/16/2018] [Accepted: 04/05/2018] [Indexed: 11/25/2022]
Abstract
Ca2+-binding protein 1 (CaBP1) is a Ca2+-sensing protein similar to calmodulin that potently regulates voltage-gated Ca2+ channels. Unlike calmodulin, however, CaBP1 is mainly expressed in neuronal cell-types and enriched in the hippocampus, where its function is unknown. Here, we investigated the role of CaBP1 in hippocampal-dependent behaviors using mice lacking expression of CaBP1 (C-KO). By western blot, the largest CaBP1 splice variant, caldendrin, was detected in hippocampal lysates from wild-type (WT) but not C-KO mice. Compared to WT mice, C-KO mice exhibited mild deficits in spatial learning and memory in both the Barnes maze and in Morris water maze reversal learning. In contextual but not cued fear-conditioning assays, C-KO mice showed greater freezing responses than WT mice. In addition, the number of adult-born neurons in the hippocampus of C-KO mice was ∼40% of that in WT mice, as measured by bromodeoxyuridine labeling. Moreover, hippocampal long-term potentiation was significantly reduced in C-KO mice. We conclude that CaBP1 is required for cellular mechanisms underlying optimal encoding of hippocampal-dependent spatial and fear-related memories.
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Affiliation(s)
- Tian Yang
- Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, Neurology, University of Iowa, Iowa City, IA 52242, USA
| | - Jeremiah K Britt
- Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, Psychiatry, University of Iowa, Iowa City, IA 52242, USA
| | - Coral J Cintrón-Pérez
- Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, Psychiatry, University of Iowa, Iowa City, IA 52242, USA
| | - Edwin Vázquez-Rosa
- Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, Psychiatry, University of Iowa, Iowa City, IA 52242, USA
| | - Kevin V Tobin
- Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, Neurology, University of Iowa, Iowa City, IA 52242, USA
| | - Grant Stalker
- Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, Neurology, University of Iowa, Iowa City, IA 52242, USA
| | - Jason Hardie
- Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, Neurology, University of Iowa, Iowa City, IA 52242, USA
| | - Rebecca J Taugher
- Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, Psychiatry, University of Iowa, Iowa City, IA 52242, USA
| | - John Wemmie
- Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, Psychiatry, University of Iowa, Iowa City, IA 52242, USA
| | - Andrew A Pieper
- Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, Neurology, University of Iowa, Iowa City, IA 52242, USA; Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, Psychiatry, University of Iowa, Iowa City, IA 52242, USA; Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, Free Radical, University of Iowa, Iowa City, IA 52242, USA; Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, Radiation Biology Program, University of Iowa, Iowa City, IA 52242, USA; Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, Radiation Oncology Comprehensive Cancer Center, University of Iowa, Iowa City, IA 52242, USA; Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, Veterans Affairs, University of Iowa, Iowa City, IA 52242, USA; Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, Pappajohn Biomedical Institute and Iowa Neuroscience Institute, University of Iowa, Iowa City, IA 52242, USA
| | - Amy Lee
- Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, Neurology, University of Iowa, Iowa City, IA 52242, USA.
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31
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Zhou K, Cherra SJ, Goncharov A, Jin Y. Asynchronous Cholinergic Drive Correlates with Excitation-Inhibition Imbalance via a Neuronal Ca 2+ Sensor Protein. Cell Rep 2018; 19:1117-1129. [PMID: 28494862 DOI: 10.1016/j.celrep.2017.04.043] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 03/13/2017] [Accepted: 04/15/2017] [Indexed: 10/19/2022] Open
Abstract
Excitation-inhibition imbalance in neural networks is widely linked to neurological and neuropsychiatric disorders. However, how genetic factors alter neuronal activity, leading to excitation-inhibition imbalance, remains unclear. Here, using the C. elegans locomotor circuit, we examine how altering neuronal activity for varying time periods affects synaptic release pattern and animal behavior. We show that while short-duration activation of excitatory cholinergic neurons elicits a reversible enhancement of presynaptic strength, persistent activation results to asynchronous and reduced cholinergic drive, inducing imbalance between endogenous excitation and inhibition. We find that the neuronal calcium sensor protein NCS-2 is required for asynchronous cholinergic release in an activity-dependent manner and dampens excitability of inhibitory neurons non-cell autonomously. The function of NCS-2 requires its Ca2+ binding and membrane association domains. These results reveal a synaptic mechanism implicating asynchronous release in regulation of excitation-inhibition balance.
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Affiliation(s)
- Keming Zhou
- Division of Biological Sciences, Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA; Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA
| | - Salvatore J Cherra
- Division of Biological Sciences, Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Alexandr Goncharov
- Division of Biological Sciences, Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA; Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA
| | - Yishi Jin
- Division of Biological Sciences, Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA; Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA.
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32
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Dutta SM, Hadley MM, Peterman S, Jewell JS, Duncan VD, Britten RA. Quantitative Proteomic Analysis of the Hippocampus of Rats with GCR-Induced Spatial Memory Impairment. Radiat Res 2017; 189:136-145. [PMID: 29206597 DOI: 10.1667/rr14822.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
NASA is planning future missions to Mars, which will result in astronauts being exposed to ∼13 cGy/year of galactic cosmic radiation (GCR). Previous ground-based experiments have demonstrated that low (15 cGy) doses of 1 GeV/n 56Fe ions impair hippocampus-dependent spatial memory in rats. However, some irradiated rats maintain a spatial memory performance comparable to that seen in the sham-irradiated rats, suggesting that some of these animals are able to ameliorate the deleterious effects of the GCR, while others are not. This rat model provides a unique opportunity to increase our understanding of how GCR affects neurophysiology, what adaptive responses can be invoked to prevent the emergence of GCR-induced spatial memory impairment, as well as the pathways that are altered when spatial memory impairment occurs. A label-free, unbiased proteomic profiling approach involving quantitative protein/peptide profiling followed by Cytoscape analysis has established the composition of the hippocampal proteome in male Wistar rats after exposure to 15 cGy of 1 GeV/n 56Fe, and identified proteins whose expression is altered with respect to: 1. radiation exposure and 2. impaired spatial memory performance. We identified 30 proteins that were classified as "GCR exposure marker" (GEM) proteins (expressed solely or at higher levels in the irradiated rats but not related to spatial memory performance), most notably CD98, Cadps and GMFB. Conversely, there were 252 proteins that were detected only in the sham-irradiated samples, i.e., they were not detected in either of the irradiated cohorts; of these 10% have well-documented roles in neurotransmission. The second aspect of our data mining was to identify proteins whose expression was associated with either impaired or functional spatial memory. While there are multiple changes in the hippocampal proteome in the irradiated rats that have impaired spatial memory performance, with 203 proteins being detected (or upregulated) only in these rats, it would appear that spatial memory impairment may also arise from an inability of these rats to express "good spatial memory" (GSM) proteins, many of which play an important role in neuronal homeostasis and function, axonogenesis, presynaptic membrane organization and G-protein coupled receptor (GCPR) signaling. It may be possible to use this knowledge to develop two alternative countermeasure strategies, one that preserves critical pathways prophylactically and one that invokes restorative pathways after GCR exposure.
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Affiliation(s)
- Sucharita M Dutta
- a Leroy T. Canoles Jr. Cancer Research Center and.,b Departments of Microbiology and Molecular Cell Biology and
| | - Melissa M Hadley
- c Radiation Oncology, Eastern Virginia Medical School, Norfolk, Virginia 23507; and
| | - Scott Peterman
- d BRIMS, Thermo Fisher Scientific, Cambridge, Massachusetts 02139
| | - Jessica S Jewell
- c Radiation Oncology, Eastern Virginia Medical School, Norfolk, Virginia 23507; and
| | - Vania D Duncan
- c Radiation Oncology, Eastern Virginia Medical School, Norfolk, Virginia 23507; and
| | - Richard A Britten
- a Leroy T. Canoles Jr. Cancer Research Center and.,b Departments of Microbiology and Molecular Cell Biology and.,c Radiation Oncology, Eastern Virginia Medical School, Norfolk, Virginia 23507; and
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33
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Helassa N, Antonyuk SV, Lian LY, Haynes LP, Burgoyne RD. Biophysical and functional characterization of hippocalcin mutants responsible for human dystonia. Hum Mol Genet 2017; 26:2426-2435. [PMID: 28398555 PMCID: PMC5886089 DOI: 10.1093/hmg/ddx133] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 03/29/2017] [Indexed: 11/13/2022] Open
Abstract
Dystonia is a neurological movement disorder that forces the body into twisting, repetitive movements or sometimes painful abnormal postures. With the advent of next-generation sequencing technologies, the homozygous mutations T71N and A190T in the neuronal calcium sensor (NCS) hippocalcin were identified as the genetic cause of primary isolated dystonia (DYT2 dystonia). However, the effect of these mutations on the physiological role of hippocalcin has not yet been elucidated. Using a multidisciplinary approach, we demonstrated that hippocalcin oligomerises in a calcium-dependent manner and binds to voltage-gated calcium channels. Mutations T71N and A190T in hippocalcin did not affect stability, calcium-binding affinity or translocation to cellular membranes (Ca2+/myristoyl switch). We obtained the first crystal structure of hippocalcin and alignment with other NCS proteins showed significant variability in the orientation of the C-terminal part of the molecule, the region expected to be important for target binding. We demonstrated that the disease-causing mutations did not affect the structure of the protein, however both mutants showed a defect in oligomerisation. In addition, we observed an increased calcium influx in KCl-depolarised cells expressing mutated hippocalcin, mostly driven by N-type voltage-gated calcium channels. Our data demonstrate that the dystonia-causing mutations strongly affect hippocalcin cellular functions which suggest a central role for perturbed calcium signalling in DYT2 dystonia.
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Affiliation(s)
- Nordine Helassa
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69?3BX, UK
| | - Svetlana V Antonyuk
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69?7ZB, UK and
| | - Lu-Yun Lian
- NMR Centre for Structural Biology, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69?7ZB, UK
| | - Lee P Haynes
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69?3BX, UK
| | - Robert D Burgoyne
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69?3BX, UK
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34
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Evans AJ, Gurung S, Wilkinson KA, Stephens DJ, Henley JM. Assembly, Secretory Pathway Trafficking, and Surface Delivery of Kainate Receptors Is Regulated by Neuronal Activity. Cell Rep 2017; 19:2613-2626. [PMID: 28636947 PMCID: PMC5489663 DOI: 10.1016/j.celrep.2017.06.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 04/17/2017] [Accepted: 05/25/2017] [Indexed: 01/03/2023] Open
Abstract
Ionotropic glutamate receptor (iGluR) trafficking and function underpin excitatory synaptic transmission and plasticity and shape neuronal networks. It is well established that the transcription, translation, and endocytosis/recycling of iGluRs are all regulated by neuronal activity, but much less is known about the activity dependence of iGluR transport through the secretory pathway. Here, we use the kainate receptor subunit GluK2 as a model iGluR cargo to show that the assembly, early secretory pathway trafficking, and surface delivery of iGluRs are all controlled by neuronal activity. We show that the delivery of de novo kainate receptors is differentially regulated by modulation of GluK2 Q/R editing, PKC phosphorylation, and PDZ ligand interactions. These findings reveal that, in addition to short-term regulation of iGluRs by recycling/endocytosis and long-term modulation by altered transcription/translation, the trafficking of iGluRs through the secretory pathway is under tight activity-dependent control to determine the numbers and properties of surface-expressed iGluRs.
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Affiliation(s)
- Ashley J Evans
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Sonam Gurung
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Kevin A Wilkinson
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - David J Stephens
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Jeremy M Henley
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK.
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35
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Park SY, Yoon SN, Kang MJ, Lee Y, Jung SJ, Han JS. Hippocalcin Promotes Neuronal Differentiation and Inhibits Astrocytic Differentiation in Neural Stem Cells. Stem Cell Reports 2016; 8:95-111. [PMID: 28017654 PMCID: PMC5233403 DOI: 10.1016/j.stemcr.2016.11.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 11/22/2016] [Accepted: 11/23/2016] [Indexed: 11/23/2022] Open
Abstract
Hippocalcin (HPCA) is a calcium-binding protein that is restricted to nervous tissue and contributes to neuronal activity. Here we report that, in addition to inducing neurogenesis, HPCA inhibits astrocytic differentiation of neural stem cells. It promotes neurogenesis by regulating protein kinase Cα (PKCα) activation by translocating to the membrane and binding to phosphoinositide-dependent protein kinase 1 (PDK1), which induces PKCα phosphorylation. We also found that phospholipase D1 (PLD1) is implicated in the HPCA-mediated neurogenesis pathway; this enzyme promotes dephosphorylation of signal transducer and activator of transcription 3 (STAT3[Y705]), which is necessary for astrocytic differentiation. Moreover, we found that the SH2-domain-containing tyrosine phosphatase 1 (SHP-1) acts upstream of STAT3. Importantly, this SHP-1-dependent STAT3-inhibitory mechanism is closely involved in neurogenesis and suppression of gliogenesis by HPCA. Taken together, these observations suggest that HPCA promotes neuronal differentiation through activation of the PKCα/PLD1 cascade followed by activation of SHP-1, which dephosphorylates STAT3(Y705), leading to inhibition of astrocytic differentiation. Hippocalcin is required for neuronal differentiation in neural stem cells PKCα/PLD1 activation is required for hippocalcin-mediated neuronal differentiation Blocking of STAT3(Y705) activity by hippocalcin decreases astrocytic differentiation Hippocalcin promotes neurogenesis by inhibiting gliogenesis in neural stem cells
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Affiliation(s)
- Shin-Young Park
- Department of Biochemistry and Molecular Biology, Biomedical Research Institute, College of Medicine, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Sung Nyo Yoon
- Department of Biochemistry and Molecular Biology, Biomedical Research Institute, College of Medicine, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Min-Jeong Kang
- Department of Biochemistry and Molecular Biology, Biomedical Research Institute, College of Medicine, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - YunYoung Lee
- Department of Biochemistry and Molecular Biology, Biomedical Research Institute, College of Medicine, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Sung Jun Jung
- Department of Physiology, College of Medicine, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Joong-Soo Han
- Department of Biochemistry and Molecular Biology, Biomedical Research Institute, College of Medicine, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea.
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36
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Kang MJ, Park SY, Han JS. Hippocalcin Is Required for Astrocytic Differentiation through Activation of Stat3 in Hippocampal Neural Precursor Cells. Front Mol Neurosci 2016; 9:110. [PMID: 27840601 PMCID: PMC5083843 DOI: 10.3389/fnmol.2016.00110] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 10/13/2016] [Indexed: 01/19/2023] Open
Abstract
Hippocalcin (Hpca) is a neuronal calcium sensor protein expressed in the mammalian brain. However, its function in neural stem/precursor cells has not yet been studied. Here, we clarify the function of Hpca in astrocytic differentiation in hippocampal neural precursor cells (HNPCs). When we overexpressed Hpca in HNPCs in the presence or absence of bFGF, expression levels of nerve-growth factors such as neurotrophin-3 (NT-3), neurotrophin-4/5 (NT-4/5), and brain-derived neurotrophic factor (BDNF), together with the proneural basic helix loop helix (bHLH) transcription factors NeuroD and neurogenin 1 (Ngn1), increased significantly. In addition, there was an increase in the number of cells expressing glial fibrillary acidic protein (GFAP), an astrocyte marker, and in branch outgrowth, indicating astrocytic differentiation of the HNPCs. Downregulation of Hpca by transfection with Hpca siRNA reduced expression of NT-3, NT-4/5, BDNF, NeuroD, and Ngn1 as well as levels of GFAP protein. Furthermore, overexpression of Hpca increased the phosphorylation of STAT3 (Ser727), and this effect was abolished by treatment with a STAT3 inhibitor (S3I-201), suggesting that STAT3 (Ser727) activation is involved in Hpca-mediated astrocytic differentiation. As expected, treatment with Stat3 siRNA or STAT3 inhibitor caused a complete inhibition of astrogliogenesis induced by Hpca overexpression. Taken together, this is the first report to show that Hpca, acting through Stat3, has an important role in the expression of neurotrophins and proneural bHLH transcription factors, and that it is an essential regulator of astrocytic differentiation and branch outgrowth in HNPCs.
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Affiliation(s)
- Min-Jeong Kang
- Department of Biomedical Sciences, Graduate School of Biomedical Science and Engineering, Hanyang University Seoul, South Korea
| | - Shin-Young Park
- Department of Biochemistry and Molecular Biology, Biomedical Research Institute, College of Medicine, Hanyang University Seoul, South Korea
| | - Joong-Soo Han
- Department of Biomedical Sciences, Graduate School of Biomedical Science and Engineering, Hanyang UniversitySeoul, South Korea; Department of Biochemistry and Molecular Biology, Biomedical Research Institute, College of Medicine, Hanyang UniversitySeoul, South Korea
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Choi HS, Lee CH. Time-course changes of hippocalcin expression in the mouse hippocampus following pilocarpine-induced status epilepticus. J Vet Sci 2016; 17:137-44. [PMID: 26435544 PMCID: PMC4921661 DOI: 10.4142/jvs.2016.17.2.137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 07/14/2015] [Accepted: 08/22/2015] [Indexed: 11/20/2022] Open
Abstract
Hippocalcin participates in the maintenance of neuronal calcium homeostasis. In the present study, we examined the time-course changes of neuronal degeneration and hippocalcin protein level in the mouse hippocampus following pilocarpine-induced status epilepticus (SE). Marked neuronal degeneration was observed in the hippocampus after SE in a time-dependent manner, although neuronal degeneration differed according to the hippocampal subregions. Almost no hippocalcin immunoreactivity was detected in the pyramidal neurons of the cornu ammonis 1 (CA1) region from 6 h after SE. However, many pyramidal neurons in the CA2 region showed hippocalcin immunoreactivity until 24 h after SE. In the CA3 region, only a few hippocalcin immunoreactive cells were observed at 12 h after SE, and almost no hippocalcin immunoreactivity was observed in the pyramidal neurons from 24 h after SE. Hippocalcin immunoreactivity in the polymorphic cells of the dentate gyrus was markedly decreased from 6 h after SE. In addition, hippocalcin protein level in the hippocampus began to decrease from 6 h after SE, and was significantly decreased at 24 h and 48 h after pilocarpine-induced SE. These results indicate that marked reduction of hippocalcin level may be closely related to neuronal degeneration in the hippocampus following pilocarpine-induced SE.
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Affiliation(s)
- Hee-Soo Choi
- Department of Pharmacy, College of Pharmacy, Dankook University, Cheonan 31116, Korea
| | - Choong-Hyun Lee
- Department of Pharmacy, College of Pharmacy, Dankook University, Cheonan 31116, Korea
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38
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Abstract
Provocative emerging evidence suggests that the N-methyl-d-aspartate (NMDA) receptor can signal in the absence of ion flux through the receptor. This non-ionotropic signaling is thought to be due to agonist-induced conformational changes in the receptor, independently of channel opening. Non-ionotropic NMDA receptor signaling has been proposed to be sufficient to induce synaptic long-term depression (LTD), directly challenging the decades-old model that prolonged low-level calcium influx is required to induce LTD. Here, we briefly review these recent findings, focusing primarily on the potential role of non-ionotropic signaling in NMDA receptor-mediated LTD. Further reports concerning additional roles of non-ionotropic NMDA receptor signaling are also discussed. If validated, this new view of NMDA receptor-mediated signaling will usher in an exciting new era of exploring synapse function and dysfunction.
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Affiliation(s)
- John A Gray
- Center for Neuroscience, University of California, Davis, CA, USA; Department of Neurology, University of California, Davis, CA, USA
| | - Karen Zito
- Center for Neuroscience, University of California, Davis, CA, USA; Department of Neurobiology, Physiology & Behavior, University of California, Davis, CA, USA
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, CA, USA
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Krishnan A, Viviano J, Morozov Y, Venkataraman V. Single-column purification of the tag-free, recombinant form of the neuronal calcium sensor protein, hippocalcin expressed in Escherichia coli. Protein Expr Purif 2016; 123:35-41. [PMID: 27001424 DOI: 10.1016/j.pep.2016.03.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Revised: 03/07/2016] [Accepted: 03/16/2016] [Indexed: 01/24/2023]
Abstract
Hippocalcin is a 193 aa protein that is a member of the neuronal calcium sensor protein family, whose functions are regulated by calcium. Mice that lack the function of this protein are compromised in the long term potentiation aspect of memory generation. Recently, mutations in the gene have been linked with dystonia in human. The protein has no intrinsic enzyme activity but is known to bind to variety of target proteins. Very little information is available on how the protein executes its critical role in signaling pathways, except that it is regulated by binding of calcium. Further delineation of its function requires large amounts of pure protein. In this report, we present a single-step purification procedure that yields high quantities of the bacterially expressed, recombinant protein. The procedure may be adapted to purify the protein from inclusion bodies or cytosol in its myristoylated or non-myristoylated forms. MALDI-MS (in source decay) analyses demonstrates that the myristoylation occurs at the glycine residue. The protein is also biologically active as measured through tryptophan fluorescence, mobility shift and guanylate cyclase activity assays. Thus, further analyses of hippocalcin, both structural and functional, need no longer be limited by protein availability.
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Affiliation(s)
- Anuradha Krishnan
- Graduate School of Biomedical Sciences, Rowan University, Stratford, NJ 08084, USA
| | - Jeffrey Viviano
- Graduate School of Biomedical Sciences, Rowan University, Stratford, NJ 08084, USA
| | - Yaroslav Morozov
- Graduate School of Biomedical Sciences, Rowan University, Stratford, NJ 08084, USA
| | - Venkat Venkataraman
- Graduate School of Biomedical Sciences, Rowan University, Stratford, NJ 08084, USA; School of Osteopathic Medicine, Rowan University, Stratford, NJ 08084, USA.
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40
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Transferrin Receptor Controls AMPA Receptor Trafficking Efficiency and Synaptic Plasticity. Sci Rep 2016; 6:21019. [PMID: 26880306 PMCID: PMC4754636 DOI: 10.1038/srep21019] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 01/14/2016] [Indexed: 02/05/2023] Open
Abstract
Transferrin receptor (TFR) is an important iron transporter regulating iron homeostasis and has long been used as a marker for clathrin mediated endocytosis. However, little is known about its additional function other than iron transport in the development of central nervous system (CNS). Here we demonstrate that TFR functions as a regulator to control AMPA receptor trafficking efficiency and synaptic plasticity. The conditional knockout (KO) of TFR in neural progenitor cells causes mice to develop progressive epileptic seizure, and dramatically reduces basal synaptic transmission and long-term potentiation (LTP). We further demonstrate that TFR KO remarkably reduces the binding efficiency of GluR2 to AP2 and subsequently decreases AMPA receptor endocytosis and recycling. Thus, our study reveals that TFR functions as a novel regulator to control AMPA trafficking efficiency and synaptic plasticity.
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Lee K, Goodman L, Fourie C, Schenk S, Leitch B, Montgomery JM. AMPA Receptors as Therapeutic Targets for Neurological Disorders. ION CHANNELS AS THERAPEUTIC TARGETS, PART A 2016; 103:203-61. [DOI: 10.1016/bs.apcsb.2015.10.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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42
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Mencacci N, Rubio-Agusti I, Zdebik A, Asmus F, Ludtmann M, Ryten M, Plagnol V, Hauser AK, Bandres-Ciga S, Bettencourt C, Forabosco P, Hughes D, Soutar M, Peall K, Morris H, Trabzuni D, Tekman M, Stanescu H, Kleta R, Carecchio M, Zorzi G, Nardocci N, Garavaglia B, Lohmann E, Weissbach A, Klein C, Hardy J, Pittman A, Foltynie T, Abramov A, Gasser T, Bhatia K, Wood N. A missense mutation in KCTD17 causes autosomal dominant myoclonus-dystonia. Am J Hum Genet 2015; 96:938-47. [PMID: 25983243 DOI: 10.1016/j.ajhg.2015.04.008] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 04/13/2015] [Indexed: 12/25/2022] Open
Abstract
Myoclonus-dystonia (M-D) is a rare movement disorder characterized by a combination of non-epileptic myoclonic jerks and dystonia. SGCE mutations represent a major cause for familial M-D being responsible for 30%-50% of cases. After excluding SGCE mutations, we identified through a combination of linkage analysis and whole-exome sequencing KCTD17 c.434 G>A p.(Arg145His) as the only segregating variant in a dominant British pedigree with seven subjects affected by M-D. A subsequent screening in a cohort of M-D cases without mutations in SGCE revealed the same KCTD17 variant in a German family. The clinical presentation of the KCTD17-mutated cases was distinct from the phenotype usually observed in M-D due to SGCE mutations. All cases initially presented with mild myoclonus affecting the upper limbs. Dystonia showed a progressive course, with increasing severity of symptoms and spreading from the cranio-cervical region to other sites. KCTD17 is abundantly expressed in all brain regions with the highest expression in the putamen. Weighted gene co-expression network analysis, based on mRNA expression profile of brain samples from neuropathologically healthy individuals, showed that KCTD17 is part of a putamen gene network, which is significantly enriched for dystonia genes. Functional annotation of the network showed an over-representation of genes involved in post-synaptic dopaminergic transmission. Functional studies in mutation bearing fibroblasts demonstrated abnormalities in endoplasmic reticulum-dependent calcium signaling. In conclusion, we demonstrate that the KCTD17 c.434 G>A p.(Arg145His) mutation causes autosomal dominant M-D. Further functional studies are warranted to further characterize the nature of KCTD17 contribution to the molecular pathogenesis of M-D.
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Mutations in HPCA cause autosomal-recessive primary isolated dystonia. Am J Hum Genet 2015; 96:657-65. [PMID: 25799108 PMCID: PMC4385177 DOI: 10.1016/j.ajhg.2015.02.007] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Accepted: 02/06/2015] [Indexed: 12/20/2022] Open
Abstract
Reports of primary isolated dystonia inherited in an autosomal-recessive (AR) manner, often lumped together as “DYT2 dystonia,” have appeared in the scientific literature for several decades, but no genetic cause has been identified to date. Using a combination of homozygosity mapping and whole-exome sequencing in a consanguineous kindred affected by AR isolated dystonia, we identified homozygous mutations in HPCA, a gene encoding a neuronal calcium sensor protein found almost exclusively in the brain and at particularly high levels in the striatum, as the cause of disease in this family. Subsequently, compound-heterozygous mutations in HPCA were also identified in a second independent kindred affected by AR isolated dystonia. Functional studies suggest that hippocalcin might play a role in regulating voltage-dependent calcium channels. The identification of mutations in HPCA as a cause of AR primary isolated dystonia paves the way for further studies to assess whether “DYT2 dystonia” is a genetically homogeneous condition or not.
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Garafalo SD, Luth ES, Moss BJ, Monteiro MI, Malkin E, Juo P. The AP2 clathrin adaptor protein complex regulates the abundance of GLR-1 glutamate receptors in the ventral nerve cord of Caenorhabditis elegans. Mol Biol Cell 2015; 26:1887-900. [PMID: 25788288 PMCID: PMC4436833 DOI: 10.1091/mbc.e14-06-1048] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 03/06/2015] [Indexed: 01/23/2023] Open
Abstract
Regulation of glutamate receptor trafficking controls synaptic strength and plasticity. This study takes advantage of viable, null mutations in subunits of the clathrin adaptor protein 2 (AP2) complex in Caenorhabditis elegans to reveal a novel and unexpected AP2-dependent trafficking step for glutamate receptors early in the secretory pathway. Regulation of glutamate receptor (GluR) abundance at synapses by clathrin-mediated endocytosis can control synaptic strength and plasticity. We take advantage of viable, null mutations in subunits of the clathrin adaptor protein 2 (AP2) complex in Caenorhabditis elegans to characterize the in vivo role of AP2 in GluR trafficking. In contrast to our predictions for an endocytic adaptor, we found that levels of the GluR GLR-1 are decreased at synapses in the ventral nerve cord (VNC) of animals with mutations in the AP2 subunits APM-2/μ2, APA-2/α, or APS-2/σ2. Rescue experiments indicate that APM-2/μ2 functions in glr-1–expressing interneurons and the mature nervous system to promote GLR-1 levels in the VNC. Genetic analyses suggest that APM-2/μ2 acts upstream of GLR-1 endocytosis in the VNC. Consistent with this, GLR-1 accumulates in cell bodies of apm-2 mutants. However, GLR-1 does not appear to accumulate at the plasma membrane of the cell body as expected, but instead accumulates in intracellular compartments including Syntaxin-13– and RAB-14–labeled endosomes. This study reveals a novel role for the AP2 clathrin adaptor in promoting the abundance of GluRs at synapses in vivo, and implicates AP2 in the regulation of GluR trafficking at an early step in the secretory pathway.
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Affiliation(s)
- Steven D Garafalo
- Department of Developmental, Molecular & Chemical Biology Graduate Program in Cellular and Molecular Physiology, Tufts University School of Medicine, Boston, MA 02111
| | - Eric S Luth
- Department of Developmental, Molecular & Chemical Biology
| | - Benjamin J Moss
- Department of Developmental, Molecular & Chemical Biology Graduate Program in Neuroscience, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111
| | - Michael I Monteiro
- Department of Developmental, Molecular & Chemical Biology Graduate Program in Cellular and Molecular Physiology, Tufts University School of Medicine, Boston, MA 02111
| | - Emily Malkin
- Department of Developmental, Molecular & Chemical Biology
| | - Peter Juo
- Department of Developmental, Molecular & Chemical Biology
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Dalgard CL, Jacobowitz DM, Singh VK, Saleem KS, Ursano RJ, Starr JM, Pollard HB. A novel analytical brain block tool to enable functional annotation of discriminatory transcript biomarkers among discrete regions of the fronto-limbic circuit in primate brain. Brain Res 2015; 1600:42-58. [DOI: 10.1016/j.brainres.2014.12.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 12/07/2014] [Accepted: 12/11/2014] [Indexed: 01/05/2023]
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46
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Lin CW, Chang LC, Tseng GC, Kirkwood CM, Sibille EL, Sweet RA. VSNL1 Co-Expression Networks in Aging Include Calcium Signaling, Synaptic Plasticity, and Alzheimer's Disease Pathways. Front Psychiatry 2015; 6:30. [PMID: 25806004 PMCID: PMC4353182 DOI: 10.3389/fpsyt.2015.00030] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 02/12/2015] [Indexed: 01/01/2023] Open
Abstract
The visinin-like 1 (VSNL1) gene encodes visinin-like protein 1, a peripheral biomarker for Alzheimer disease (AD). Little is known, however, about normal VSNL1 expression in brain and the biologic networks in which it participates. Frontal cortex gray matter obtained from 209 subjects without neurodegenerative or psychiatric illness, ranging in age from 16 to 91, was processed on Affymetrix GeneChip 1.1 ST and Human SNP Array 6.0. VSNL1 expression was unaffected by age and sex, and not significantly associated with SNPs in cis or trans. VSNL1 was significantly co-expressed with genes in pathways for calcium signaling, AD, long-term potentiation, long-term depression, and trafficking of AMPA receptors. The association with AD was driven, in part, by correlation with amyloid precursor protein (APP) expression. These findings provide an unbiased link between VSNL1 and molecular mechanisms of AD, including pathways implicated in synaptic pathology in AD. Whether APP may drive increased VSNL1 expression, VSNL1 drives increased APP expression, or both are downstream of common pathogenic regulators will need to be evaluated in model systems.
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Affiliation(s)
- Chien-Wei Lin
- Department of Biostatistics, University of Pittsburgh , Pittsburgh, PA , USA
| | - Lun-Ching Chang
- Department of Biostatistics, University of Pittsburgh , Pittsburgh, PA , USA
| | - George C Tseng
- Department of Biostatistics, University of Pittsburgh , Pittsburgh, PA , USA
| | - Caitlin M Kirkwood
- Department of Psychiatry, University of Pittsburgh , Pittsburgh, PA , USA
| | - Etienne L Sibille
- Department of Psychiatry, University of Pittsburgh , Pittsburgh, PA , USA ; Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Departments of Psychiatry and Pharmacology & Toxicology, University of Toronto , Toronto, ON , Canada
| | - Robert A Sweet
- Department of Psychiatry, University of Pittsburgh , Pittsburgh, PA , USA ; Department of Neurology, University of Pittsburgh , Pittsburgh, PA , USA ; VISN 4 Mental Illness Research, Education and Clinical Center (MIRECC), VA Pittsburgh Healthcare System , Pittsburgh, PA , USA
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47
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Burgoyne RD, Haynes LP. Sense and specificity in neuronal calcium signalling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:1921-32. [PMID: 25447549 PMCID: PMC4728190 DOI: 10.1016/j.bbamcr.2014.10.029] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 10/25/2014] [Accepted: 10/29/2014] [Indexed: 11/02/2022]
Abstract
Changes in the intracellular free calcium concentration ([Ca²⁺]i) in neurons regulate many and varied aspects of neuronal function over time scales from microseconds to days. The mystery is how a single signalling ion can lead to such diverse and specific changes in cell function. This is partly due to aspects of the Ca²⁺ signal itself, including its magnitude, duration, localisation and persistent or oscillatory nature. The transduction of the Ca²⁺ signal requires Ca²⁺binding to various Ca²⁺ sensor proteins. The different properties of these sensors are important for differential signal processing and determine the physiological specificity of Ca(2+) signalling pathways. A major factor underlying the specific roles of particular Ca²⁺ sensor proteins is the nature of their interaction with target proteins and how this mediates unique patterns of regulation. We review here recent progress from structural analyses and from functional analyses in model organisms that have begun to reveal the rules that underlie Ca²⁺ sensor protein specificity for target interaction. We discuss three case studies exemplifying different aspects of Ca²⁺ sensor/target interaction. This article is part of a special issue titled the 13th European Symposium on Calcium.
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Affiliation(s)
- Robert D Burgoyne
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, United Kingdom.
| | - Lee P Haynes
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, United Kingdom
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48
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Goswami SC, Mishra SK, Maric D, Kaszas K, Gonnella GL, Clokie SJ, Kominsky HD, Gross JR, Keller JM, Mannes AJ, Hoon MA, Iadarola MJ. Molecular signatures of mouse TRPV1-lineage neurons revealed by RNA-Seq transcriptome analysis. THE JOURNAL OF PAIN 2014; 15:1338-1359. [PMID: 25281809 DOI: 10.1016/j.jpain.2014.09.010] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 09/10/2014] [Accepted: 09/19/2014] [Indexed: 12/22/2022]
Abstract
UNLABELLED Disorders of pain neural systems are frequently chronic and, when recalcitrant to treatment, can severely degrade the quality of life. The pain pathway begins with sensory neurons in dorsal root or trigeminal ganglia, and the neuronal subpopulations that express the transient receptor potential cation channel, subfamily V, member 1 (TRPV1) ion channel transduce sensations of painful heat and inflammation and play a fundamental role in clinical pain arising from cancer and arthritis. In the present study, we elucidate the complete transcriptomes of neurons from the TRPV1 lineage and a non-TRPV1 neuroglial population in sensory ganglia through the combined application of next-gen deep RNA-Seq, genetic neuronal labeling with fluorescence-activated cell sorting, or neuron-selective chemoablation. RNA-Seq accurately quantitates gene expression, a difficult parameter to determine with most other methods, especially for very low and very high expressed genes. Differentially expressed genes are present at every level of cellular function from the nucleus to the plasma membrane. We identified many ligand receptor pairs in the TRPV1 population, suggesting that autonomous presynaptic regulation may be a major regulatory mechanism in nociceptive neurons. The data define, in a quantitative, cell population-specific fashion, the molecular signature of a distinct and clinically important group of pain-sensing neurons and provide an overall framework for understanding the transcriptome of TRPV1 nociceptive neurons. PERSPECTIVE Next-gen RNA-Seq, combined with molecular genetics, provides a comprehensive and quantitative measurement of transcripts in TRPV1 lineage neurons and a contrasting transcriptome from non-TRPV1 neurons and cells. The transcriptome highlights previously unrecognized protein families, identifies multiple molecular circuits for excitatory or inhibitory autocrine and paracrine signaling, and suggests new combinatorial approaches to pain control.
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Affiliation(s)
- Samridhi C Goswami
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Santosh K Mishra
- Molecular Genetics Unit, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, Bethesda, Maryland
| | - Dragan Maric
- Laboratory of Neurophysiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Krisztian Kaszas
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Gian Luigi Gonnella
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Samuel J Clokie
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Hal D Kominsky
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Jacklyn R Gross
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Jason M Keller
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Andrew J Mannes
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Mark A Hoon
- Molecular Genetics Unit, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, Bethesda, Maryland
| | - Michael J Iadarola
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland.
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Föcking M, Opstelten R, Prickaerts J, Steinbusch HWM, Dunn MJ, van den Hove DLA, Cotter DR. Proteomic investigation of the hippocampus in prenatally stressed mice implicates changes in membrane trafficking, cytoskeletal, and metabolic function. Dev Neurosci 2014; 36:432-42. [PMID: 25138076 DOI: 10.1159/000365327] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 06/17/2014] [Indexed: 11/19/2022] Open
Abstract
Prenatal stress influences the development of the fetal brain and so contributes to the risk of the development of psychiatric disorders in later life. The hippocampus is particularly sensitive to prenatal stress, and robust abnormalities have been described in the hippocampus in schizophrenia and depression. The aim of this study was to determine whether prenatal stress is associated with distinct patterns of differential protein expression in the hippocampus using a validated mouse model. We therefore performed a comparative proteomic study assessing female hippocampal samples from 8 prenatally stressed mice and 8 control mice. Differential protein expression was assessed using 2-dimensional difference in gel electrophoresis and subsequent mass spectrometry. The observed changes in a selected group of differentially expressed proteins were confirmed by Western blotting. In comparison to controls, 47 protein spots (38 individual proteins) were found to be differentially expressed in the hippocampus of prenatally stressed mice. Functional grouping of these proteins revealed that prenatal stress influenced the expression of proteins involved in brain development, cytoskeletal composition, stress response, and energy metabolism. Western blotting was utilized to validate the changes in calretinin, hippocalcin, profilin-1 and the signal-transducing adaptor molecule STAM1. Septin-5 could not be validated via Western blotting due to methodological issues. Closer investigation of the validated proteins also pointed to an interesting role for membrane trafficking deficits mediated by prenatal stress. Our findings demonstrate that prenatal stress leads to altered hippocampal protein expression, implicating numerous molecular pathways that may provide new targets for psychotropic drug development.
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Affiliation(s)
- Melanie Föcking
- Department of Psychiatry, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin, Ireland
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50
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Stackpole EE, Akins MR, Fallon JR. N-myristoylation regulates the axonal distribution of the Fragile X-related protein FXR2P. Mol Cell Neurosci 2014; 62:42-50. [PMID: 25109237 DOI: 10.1016/j.mcn.2014.08.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 07/21/2014] [Accepted: 08/06/2014] [Indexed: 12/20/2022] Open
Abstract
Fragile X syndrome, the leading cause of inherited intellectual disability and autism, is caused by loss of function of Fragile X mental retardation protein (FMRP). FMRP is an RNA binding protein that regulates local protein synthesis in the somatodendritic compartment. However, emerging evidence also indicates important roles for FMRP in axonal and presynaptic functions. In particular, FMRP and its homologue FXR2P localize axonally and presynaptically to discrete endogenous structures in the brain termed Fragile X granules (FXGs). FXR2P is a component of all FXGs and is necessary for the axonal and presynaptic localization of FMRP to these structures. We therefore sought to identify and characterize structural features of FXR2P that regulate its axonal localization. Sequence analysis reveals that FXR2P harbors a consensus N-terminal myristoylation sequence (MGXXXS) that is absent in FMRP. Using click chemistry with wild type and an unmyristoylatable G2A mutant we demonstrate that FXR2P is N-myristoylated on glycine 2, establishing it as a lipid-modified RNA binding protein. To investigate the role of FXR2P N-myristoylation in neurons we generated fluorescently tagged wild type and unmyristoylatable FXR2P (WT and G2A, respectively) and expressed them in primary cortical cultures. Both FXR2P(WT) and FXR2P(G2A) are expressed at equivalent overall levels and are capable of forming FMRP-containing axonal granules. However, FXR2P(WT) granules are largely restricted to proximal axonal segments while granules formed with unmyristoylatable FXR2P(G2A) are localized throughout the axonal arbor, including in growth cones. These studies indicate that N-terminal myristoylation of the RNA binding protein FXR2P regulates its localization within the axonal arbor. Moreover, since FMRP localization within axonal domains requires its association with FXR2P, these findings suggest that FXR2P lipid modification is a control point for the axonal and presynaptic distribution of FMRP.
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Affiliation(s)
- Emily E Stackpole
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
| | - Michael R Akins
- Department of Neuroscience, Brown University, Providence, RI 02912, USA; Department of Biology, Drexel University, Philadelphia, PA 19104, USA
| | - Justin R Fallon
- Department of Neuroscience, Brown University, Providence, RI 02912, USA.
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