1
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Dong C, Gowrishankar R, Jin Y, He XJ, Gupta A, Wang H, Sayar-Atasoy N, Flores RJ, Mahe K, Tjahjono N, Liang R, Marley A, Or Mizuno G, Lo DK, Sun Q, Whistler JL, Li B, Gomes I, Von Zastrow M, Tejeda HA, Atasoy D, Devi LA, Bruchas MR, Banghart MR, Tian L. Unlocking opioid neuropeptide dynamics with genetically encoded biosensors. Nat Neurosci 2024; 27:1844-1857. [PMID: 39009835 PMCID: PMC11374718 DOI: 10.1038/s41593-024-01697-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 06/05/2024] [Indexed: 07/17/2024]
Abstract
Neuropeptides are ubiquitous in the nervous system. Research into neuropeptides has been limited by a lack of experimental tools that allow for the precise dissection of their complex and diverse dynamics in a circuit-specific manner. Opioid peptides modulate pain, reward and aversion and as such have high clinical relevance. To illuminate the spatiotemporal dynamics of endogenous opioid signaling in the brain, we developed a class of genetically encoded fluorescence sensors based on kappa, delta and mu opioid receptors: κLight, δLight and µLight, respectively. We characterized the pharmacological profiles of these sensors in mammalian cells and in dissociated neurons. We used κLight to identify electrical stimulation parameters that trigger endogenous opioid release and the spatiotemporal scale of dynorphin volume transmission in brain slices. Using in vivo fiber photometry in mice, we demonstrated the utility of these sensors in detecting optogenetically driven opioid release and observed differential opioid release dynamics in response to fearful and rewarding conditions.
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Affiliation(s)
- Chunyang Dong
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California Davis, Davis, CA, USA
| | - Raajaram Gowrishankar
- Center for the Neurobiology of Addiction, Pain, and Emotion, Departments of Anesthesiology and Pharmacology, University of Washington, Seattle, WA, USA
| | - Yihan Jin
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California Davis, Davis, CA, USA
| | - Xinyi Jenny He
- Department of Neurobiology, School of Biological Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Achla Gupta
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York City, NY, USA
| | - Huikun Wang
- Unit on Neuromodulation and Synaptic Integration, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Nilüfer Sayar-Atasoy
- Department of Neuroscience and Pharmacology, Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Rodolfo J Flores
- Unit on Neuromodulation and Synaptic Integration, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Karan Mahe
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California Davis, Davis, CA, USA
| | - Nikki Tjahjono
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California Davis, Davis, CA, USA
| | - Ruqiang Liang
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California Davis, Davis, CA, USA
| | - Aaron Marley
- Department of Pharmacology, University of California San Francisco, San Francisco, CA, USA
| | - Grace Or Mizuno
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California Davis, Davis, CA, USA
| | - Darren K Lo
- College of Biological Sciences, University of California Davis, Davis, CA, USA
| | - Qingtao Sun
- Cold Spring Harbor Laboratory, New York, NY, USA
| | | | - Bo Li
- Cold Spring Harbor Laboratory, New York, NY, USA
| | - Ivone Gomes
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York City, NY, USA
| | - Mark Von Zastrow
- Department of Pharmacology, University of California San Francisco, San Francisco, CA, USA
| | - Hugo A Tejeda
- Unit on Neuromodulation and Synaptic Integration, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Deniz Atasoy
- Department of Neuroscience and Pharmacology, Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Lakshmi A Devi
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York City, NY, USA
| | - Michael R Bruchas
- Center for the Neurobiology of Addiction, Pain, and Emotion, Departments of Anesthesiology and Pharmacology, University of Washington, Seattle, WA, USA.
| | - Matthew R Banghart
- Department of Neurobiology, School of Biological Sciences, University of California, San Diego, La Jolla, CA, USA.
| | - Lin Tian
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California Davis, Davis, CA, USA.
- Max Planck Florida Institute for Neuroscience, Jupiter, FL, USA.
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2
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Li E, van der Heyden MAG. The network of cardiac K IR2.1: its function, cellular regulation, electrical signaling, diseases and new drug avenues. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024:10.1007/s00210-024-03116-5. [PMID: 38683369 DOI: 10.1007/s00210-024-03116-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 04/19/2024] [Indexed: 05/01/2024]
Abstract
The functioning of the human heart relies on complex electrical and communication systems that coordinate cardiac contractions and sustain rhythmicity. One of the key players contributing to this intricate system is the KIR2.1 potassium ion channel, which is encoded by the KCNJ2 gene. KIR2.1 channels exhibit abundant expression in both ventricular myocytes and Purkinje fibers, exerting an important role in maintaining the balance of intracellular potassium ion levels within the heart. And by stabilizing the resting membrane potential and contributing to action potential repolarization, these channels have an important role in cardiac excitability also. Either gain- or loss-of-function mutations, but also acquired impairments of their function, are implicated in the pathogenesis of diverse types of cardiac arrhythmias. In this review, we aim to elucidate the system functions of KIR2.1 channels related to cellular electrical signaling, communication, and their contributions to cardiovascular disease. Based on this knowledge, we will discuss existing and new pharmacological avenues to modulate their function.
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Affiliation(s)
- Encan Li
- Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM, Utrecht, Netherlands
| | - Marcel A G van der Heyden
- Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM, Utrecht, Netherlands.
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3
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Ott S, Xu S, Lee N, Hong I, Anns J, Suresh DD, Zhang Z, Zhang X, Harion R, Ye W, Chandramouli V, Jesuthasan S, Saheki Y, Claridge-Chang A. Kalium channelrhodopsins effectively inhibit neurons. Nat Commun 2024; 15:3480. [PMID: 38658537 PMCID: PMC11043423 DOI: 10.1038/s41467-024-47203-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 03/18/2024] [Indexed: 04/26/2024] Open
Abstract
The analysis of neural circuits has been revolutionized by optogenetic methods. Light-gated chloride-conducting anion channelrhodopsins (ACRs)-recently emerged as powerful neuron inhibitors. For cells or sub-neuronal compartments with high intracellular chloride concentrations, however, a chloride conductance can have instead an activating effect. The recently discovered light-gated, potassium-conducting, kalium channelrhodopsins (KCRs) might serve as an alternative in these situations, with potentially broad application. As yet, KCRs have not been shown to confer potent inhibitory effects in small genetically tractable animals. Here, we evaluated the utility of KCRs to suppress behavior and inhibit neural activity in Drosophila, Caenorhabditis elegans, and zebrafish. In direct comparisons with ACR1, a KCR1 variant with enhanced plasma-membrane trafficking displayed comparable potency, but with improved properties that include reduced toxicity and superior efficacy in putative high-chloride cells. This comparative analysis of behavioral inhibition between chloride- and potassium-selective silencing tools establishes KCRs as next-generation optogenetic inhibitors for in vivo circuit analysis in behaving animals.
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Affiliation(s)
- Stanislav Ott
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Sangyu Xu
- Institute for Molecular and Cell Biology, A*STAR Agency for Science, Technology and Research, Singapore, Singapore
| | - Nicole Lee
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Ivan Hong
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Jonathan Anns
- Institute for Molecular and Cell Biology, A*STAR Agency for Science, Technology and Research, Singapore, Singapore
- School of Biological Sciences and Institute for Life Sciences, University of Southampton, Southampton, UK
| | - Danesha Devini Suresh
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Zhiyi Zhang
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Xianyuan Zhang
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Raihanah Harion
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Weiying Ye
- Department of Physiology, National University of Singapore, Singapore, Singapore
| | - Vaishnavi Chandramouli
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Suresh Jesuthasan
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Yasunori Saheki
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Adam Claridge-Chang
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore, Singapore.
- Institute for Molecular and Cell Biology, A*STAR Agency for Science, Technology and Research, Singapore, Singapore.
- Department of Physiology, National University of Singapore, Singapore, Singapore.
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4
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Wang X, Kang L, Kong D, Wu X, Zhou Y, Yu G, Dai D, Ye H. A programmable protease-based protein secretion platform for therapeutic applications. Nat Chem Biol 2024; 20:432-442. [PMID: 37872400 DOI: 10.1038/s41589-023-01433-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 09/02/2023] [Indexed: 10/25/2023]
Abstract
Cell-based therapies represent potent enabling technologies in biomedical science. However, current genetic control systems for engineered-cell therapies are predominantly based on the transcription or translation of therapeutic outputs. Here we report a protease-based rapid protein secretion system (PASS) that regulates the secretion of pretranslated proteins retained in the endoplasmic reticulum (ER) owing to an ER-retrieval signal. Upon cleavage by inducible proteases, these proteins are secreted. Three PASS variants (chemPASS, antigenPASS and optoPASS) are developed. With chemPASS, we demonstrate the reversal of hyperglycemia in diabetic mice within minutes via drug-induced insulin secretion. AntigenPASS-equipped cells recognize the tumor antigen and secrete granzyme B and perforin, inducing targeted cell apoptosis. Finally, results from mouse models of diabetes, hypertension and inflammatory pain demonstrate light-induced, optoPASS-mediated therapeutic peptide secretion within minutes, conferring anticipated therapeutic benefits. PASS is a flexible platform for rapid delivery of therapeutic proteins that can facilitate the development and adoption of cell-based precision therapies.
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Affiliation(s)
- Xinyi Wang
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Biomedical Synthetic Biology Research Center, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Liping Kang
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Biomedical Synthetic Biology Research Center, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Deqiang Kong
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Biomedical Synthetic Biology Research Center, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Xin Wu
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Biomedical Synthetic Biology Research Center, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Yang Zhou
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Biomedical Synthetic Biology Research Center, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
- Wuhu Hospital, Health Science Center, East China Normal University, Wuhu City, China
| | - Guiling Yu
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Biomedical Synthetic Biology Research Center, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Di Dai
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Biomedical Synthetic Biology Research Center, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Haifeng Ye
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Biomedical Synthetic Biology Research Center, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China.
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5
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Tian H, Davis HC, Wong-Campos JD, Park P, Fan LZ, Gmeiner B, Begum S, Werley CA, Borja GB, Upadhyay H, Shah H, Jacques J, Qi Y, Parot V, Deisseroth K, Cohen AE. Video-based pooled screening yields improved far-red genetically encoded voltage indicators. Nat Methods 2023; 20:1082-1094. [PMID: 36624211 PMCID: PMC10329731 DOI: 10.1038/s41592-022-01743-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 11/28/2022] [Indexed: 01/11/2023]
Abstract
Video-based screening of pooled libraries is a powerful approach for directed evolution of biosensors because it enables selection along multiple dimensions simultaneously from large libraries. Here we develop a screening platform, Photopick, which achieves precise phenotype-activated photoselection over a large field of view (2.3 × 2.3 mm, containing >103 cells, per shot). We used the Photopick platform to evolve archaerhodopsin-derived genetically encoded voltage indicators (GEVIs) with improved signal-to-noise ratio (QuasAr6a) and kinetics (QuasAr6b). These GEVIs gave improved signals in cultured neurons and in live mouse brains. By combining targeted in vivo optogenetic stimulation with high-precision voltage imaging, we characterized inhibitory synaptic coupling between individual cortical NDNF (neuron-derived neurotrophic factor) interneurons, and excitatory electrical synapses between individual hippocampal parvalbumin neurons. The QuasAr6 GEVIs are powerful tools for all-optical electrophysiology and the Photopick approach could be adapted to evolve a broad range of biosensors.
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Affiliation(s)
- He Tian
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Hunter C Davis
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - J David Wong-Campos
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Pojeong Park
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Linlin Z Fan
- Department of Bioengineering, Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
| | - Benjamin Gmeiner
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Shahinoor Begum
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | | | | | | | | | | | - Yitong Qi
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Vicente Parot
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Institute for Biological and Medical Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Karl Deisseroth
- Department of Bioengineering, Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Chevy Chase, MA, USA
| | - Adam E Cohen
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
- Department of Physics, Harvard University, Cambridge, MA, USA.
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6
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vom Dahl C, Müller CE, Berisha X, Nagel G, Zimmer T. Coupling the Cardiac Voltage-Gated Sodium Channel to Channelrhodopsin-2 Generates Novel Optical Switches for Action Potential Studies. MEMBRANES 2022; 12:907. [PMID: 36295666 PMCID: PMC9607247 DOI: 10.3390/membranes12100907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 09/09/2022] [Accepted: 09/12/2022] [Indexed: 06/16/2023]
Abstract
Voltage-gated sodium (Na+) channels respond to short membrane depolarization with conformational changes leading to pore opening, Na+ influx, and action potential (AP) upstroke. In the present study, we coupled channelrhodopsin-2 (ChR2), the key ion channel in optogenetics, directly to the cardiac voltage-gated Na+ channel (Nav1.5). Fusion constructs were expressed in Xenopus laevis oocytes, and electrophysiological recordings were performed by the two-microelectrode technique. Heteromeric channels retained both typical Nav1.5 kinetics and light-sensitive ChR2 properties. Switching to the current-clamp mode and applying short blue-light pulses resulted either in subthreshold depolarization or in a rapid change of membrane polarity typically seen in APs of excitable cells. To study the effect of individual K+ channels on the AP shape, we co-expressed either Kv1.2 or hERG with one of the Nav1.5-ChR2 fusions. As expected, both delayed rectifier K+ channels shortened AP duration significantly. Kv1.2 currents remarkably accelerated initial repolarization, whereas hERG channel activity efficiently restored the resting membrane potential. Finally, we investigated the effect of the LQT3 deletion mutant ΔKPQ on the AP shape and noticed an extremely prolonged AP duration that was directly correlated to the size of the non-inactivating Na+ current fraction. In conclusion, coupling of ChR2 to a voltage-gated Na+ channel generates optical switches that are useful for studying the effect of individual ion channels on the AP shape. Moreover, our novel optogenetic approach provides the potential for an application in pharmacology and optogenetic tissue-engineering.
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Affiliation(s)
- Christian vom Dahl
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, 07740 Jena, Germany
| | - Christoph Emanuel Müller
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, 07740 Jena, Germany
| | - Xhevat Berisha
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, 07740 Jena, Germany
| | - Georg Nagel
- Institute of Physiology—Neurophysiology, Julius Maximilians University, 97070 Wuerzburg, Germany
| | - Thomas Zimmer
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, 07740 Jena, Germany
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7
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Lee S, Kang BE, Song YK, Baker BJ. A trafficking motif alters GEVI activity implicating persistent protein interactions at the membrane. BIOPHYSICAL REPORTS 2022; 2:100047. [PMID: 36425771 PMCID: PMC9680705 DOI: 10.1016/j.bpr.2022.100047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Accepted: 02/18/2022] [Indexed: 11/30/2022]
Abstract
Efficient plasma-membrane expression is critical for genetically encoded voltage indicators (GEVIs). To improve the plasma-membrane expression, we introduced multiple combinations of plasma-membrane trafficking motifs at different positions to members of the Bongwoori family of GEVIs. An improvement from 20% to 27% in the ΔF/F/100 mV depolarization of the plasma membrane was observed when a Golgi transport motif was inserted near the N-terminus in conjunction with an endoplasmic reticulum release motif near the C-terminus of the protein. Unfortunately, this variant was also slower. The weighted tau on of the variant (25 ms) was more than double the original construct (11 ms). The weighted tau off was >20 ms compared with 10 ms for the original GEVI. The voltage range of the GEVI was also shifted to more negative potentials. Insertion of spacer amino acids between the fluorescent-protein domain and the endoplasmic reticulum release motif at the C-terminus rescued the speed of both the tau on and tau off while restoring the voltage range and maintaining the improved voltage-dependent optical signal. These results suggest that while trafficking motifs do improve plasma-membrane expression, they may also mediate persistent associations that affect the functioning of the protein.
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8
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Coyote-Maestas W, Nedrud D, He Y, Schmidt D. Determinants of trafficking, conduction, and disease within a K + channel revealed through multiparametric deep mutational scanning. eLife 2022; 11:e76903. [PMID: 35639599 PMCID: PMC9273215 DOI: 10.7554/elife.76903] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Accepted: 05/27/2022] [Indexed: 01/04/2023] Open
Abstract
A long-standing goal in protein science and clinical genetics is to develop quantitative models of sequence, structure, and function relationships to understand how mutations cause disease. Deep mutational scanning (DMS) is a promising strategy to map how amino acids contribute to protein structure and function and to advance clinical variant interpretation. Here, we introduce 7429 single-residue missense mutations into the inward rectifier K+ channel Kir2.1 and determine how this affects folding, assembly, and trafficking, as well as regulation by allosteric ligands and ion conduction. Our data provide high-resolution information on a cotranslationally folded biogenic unit, trafficking and quality control signals, and segregated roles of different structural elements in fold stability and function. We show that Kir2.1 surface trafficking mutants are underrepresented in variant effect databases, which has implications for clinical practice. By comparing fitness scores with expert-reviewed variant effects, we can predict the pathogenicity of 'variants of unknown significance' and disease mechanisms of known pathogenic mutations. Our study in Kir2.1 provides a blueprint for how multiparametric DMS can help us understand the mechanistic basis of genetic disorders and the structure-function relationships of proteins.
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Affiliation(s)
- Willow Coyote-Maestas
- Department of Biochemistry, Molecular Biology and Biophysics, University of MinnesotaMinneapolisUnited States
| | - David Nedrud
- Department of Biochemistry, Molecular Biology and Biophysics, University of MinnesotaMinneapolisUnited States
| | - Yungui He
- Department of Genetics, Cell Biology and Development, University of MinnesotaMinneapolisUnited States
| | - Daniel Schmidt
- Department of Genetics, Cell Biology and Development, University of MinnesotaMinneapolisUnited States
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9
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Protease-controlled secretion and display of intercellular signals. Nat Commun 2022; 13:912. [PMID: 35177637 PMCID: PMC8854555 DOI: 10.1038/s41467-022-28623-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 02/03/2022] [Indexed: 02/07/2023] Open
Abstract
To program intercellular communication for biomedicine, it is crucial to regulate the secretion and surface display of signaling proteins. If such regulations are at the protein level, there are additional advantages, including compact delivery and direct interactions with endogenous signaling pathways. Here we create a modular, generalizable design called Retained Endoplasmic Cleavable Secretion (RELEASE), with engineered proteins retained in the endoplasmic reticulum and displayed/secreted in response to specific proteases. The design allows functional regulation of multiple synthetic and natural proteins by synthetic protease circuits to realize diverse signal processing capabilities, including logic operation and threshold tuning. By linking RELEASE to additional sensing and processing circuits, we can achieve elevated protein secretion in response to "undruggable" oncogene KRAS mutants. RELEASE should enable the local, programmable delivery of intercellular cues for a broad variety of fields such as neurobiology, cancer immunotherapy and cell transplantation.
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10
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Li E, Loen V, van Ham WB, Kool W, van der Heyden MAG, Takanari H. Quantitative Analysis of the Cytoskeleton's Role in Inward Rectifier K IR 2.1 Forward and Backward Trafficking. Front Physiol 2022; 12:812572. [PMID: 35145427 PMCID: PMC8821923 DOI: 10.3389/fphys.2021.812572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 12/23/2021] [Indexed: 11/13/2022] Open
Abstract
Alteration of the inward rectifier current IK1, carried by KIR2.1 channels, affects action potential duration, impacts resting membrane stability and associates with cardiac arrhythmias. Congenital and acquired KIR2.1 malfunction frequently associates with aberrant ion channel trafficking. Cellular processes underlying trafficking are intertwined with cytoskeletal function. The extent to which the cytoskeleton is involved in KIR2.1 trafficking processes is unknown. We aimed to quantify the dependence of KIR2.1 trafficking on cytoskeleton function. GFP or photoconvertible Dendra2 tagged KIR2.1 constructs were transfected in HEK293 or HeLa cells. Photoconversion of the Dendra2 probe at the plasma membrane and subsequent live imaging of trafficking processes was performed by confocal laser-scanning microscopy. Time constant of green fluorescent recovery (τg,s) represented recruitment of new KIR2.1 at the plasma membrane. Red fluorescent decay (τr,s) represented internalization of photoconverted KIR2.1. Patch clamp electrophysiology was used to quantify IKIR2.1. Biochemical methods were used for cytoskeleton isolation and detection of KIR2.1-cytoskeleton interactions. Cytochalasin B (20 μM), Nocodazole (30 μM) and Dyngo-4a (10 nM) were used to modify the cytoskeleton. Chloroquine (10 μM, 24 h) was used to impair KIR2.1 breakdown. Cytochalasin B and Nocodazole, inhibitors of actin and tubulin filament formation respectively, strongly inhibited the recovery of green fluorescence at the plasma membrane suggestive for inhibition of KIR2.1 forward trafficking [τg,s 13 ± 2 vs. 131 ± 31* and 160 ± 40* min, for control, Cytochalasin B and Nocodazole, respectively (*p < 0.05 vs. control)]. Dyngo-4a, an inhibitor of dynamin motor proteins, strongly slowed the rate of photoconverted channel internalization, whereas Nocodazole and Cytochalasin B had less effect [τr,s 20 ± 2 vs. 87 ± 14*, 60 ± 16 and 64 ± 20 min (*p < 0.05 vs. control)]. Cytochalasin B treatment (20 μM, 24 h) inhibited IKIR2.1. Chloroquine treatment (10 μM, 24 h) induced intracellular aggregation of KIR2.1 channels and enhanced interaction with the actin/intermediate filament system (103 ± 90 fold; p < 0.05 vs. control). Functional actin and tubulin cytoskeleton systems are essential for forward trafficking of KIR2.1 channels, whereas initial backward trafficking relies on a functional dynamin system. Chronic disturbance of the actin system inhibits KIR2.1 currents. Internalized KIR2.1 channels become recruited to the cytoskeleton, presumably in lysosomes.
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Affiliation(s)
- Encan Li
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Vera Loen
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Willem B van Ham
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Willy Kool
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Marcel A G van der Heyden
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Hiroki Takanari
- Department of Interdisciplinary Researches for Medicine and Photonics, Institute of Post-LED Photonics, University of Tokushima, Tokushima, Japan
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11
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Hager NA, McAtee CK, Lesko MA, O’Donnell AF. Inwardly Rectifying Potassium Channel Kir2.1 and its "Kir-ious" Regulation by Protein Trafficking and Roles in Development and Disease. Front Cell Dev Biol 2022; 9:796136. [PMID: 35223865 PMCID: PMC8864065 DOI: 10.3389/fcell.2021.796136] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Accepted: 12/15/2021] [Indexed: 11/13/2022] Open
Abstract
Potassium (K+) homeostasis is tightly regulated for optimal cell and organismal health. Failure to control potassium balance results in disease, including cardiac arrythmias and developmental disorders. A family of inwardly rectifying potassium (Kir) channels helps cells maintain K+ levels. Encoded by KCNJ genes, Kir channels are comprised of a tetramer of Kir subunits, each of which contains two-transmembrane domains. The assembled Kir channel generates an ion selectivity filter for K+ at the monomer interface, which allows for K+ transit. Kir channels are found in many cell types and influence K+ homeostasis across the organism, impacting muscle, nerve and immune function. Kir2.1 is one of the best studied family members with well-defined roles in regulating heart rhythm, muscle contraction and bone development. Due to their expansive roles, it is not surprising that Kir mutations lead to disease, including cardiomyopathies, and neurological and metabolic disorders. Kir malfunction is linked to developmental defects, including underdeveloped skeletal systems and cerebellar abnormalities. Mutations in Kir2.1 cause the periodic paralysis, cardiac arrythmia, and developmental deficits associated with Andersen-Tawil Syndrome. Here we review the roles of Kir family member Kir2.1 in maintaining K+ balance with a specific focus on our understanding of Kir2.1 channel trafficking and emerging roles in development and disease. We provide a synopsis of the vital work focused on understanding the trafficking of Kir2.1 and its role in development.
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Affiliation(s)
| | | | | | - Allyson F. O’Donnell
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, United States
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12
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Coyote-Maestas W, Nedrud D, Suma A, He Y, Matreyek KA, Fowler DM, Carnevale V, Myers CL, Schmidt D. Probing ion channel functional architecture and domain recombination compatibility by massively parallel domain insertion profiling. Nat Commun 2021; 12:7114. [PMID: 34880224 PMCID: PMC8654947 DOI: 10.1038/s41467-021-27342-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 11/16/2021] [Indexed: 11/10/2022] Open
Abstract
Protein domains are the basic units of protein structure and function. Comparative analysis of genomes and proteomes showed that domain recombination is a main driver of multidomain protein functional diversification and some of the constraining genomic mechanisms are known. Much less is known about biophysical mechanisms that determine whether protein domains can be combined into viable protein folds. Here, we use massively parallel insertional mutagenesis to determine compatibility of over 300,000 domain recombination variants of the Inward Rectifier K+ channel Kir2.1 with channel surface expression. Our data suggest that genomic and biophysical mechanisms acted in concert to favor gain of large, structured domain at protein termini during ion channel evolution. We use machine learning to build a quantitative biophysical model of domain compatibility in Kir2.1 that allows us to derive rudimentary rules for designing domain insertion variants that fold and traffic to the cell surface. Positional Kir2.1 responses to motif insertion clusters into distinct groups that correspond to contiguous structural regions of the channel with distinct biophysical properties tuned towards providing either folding stability or gating transitions. This suggests that insertional profiling is a high-throughput method to annotate function of ion channel structural regions.
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Affiliation(s)
- Willow Coyote-Maestas
- grid.17635.360000000419368657Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, Minneapolis, MN 55455 USA
| | - David Nedrud
- grid.17635.360000000419368657Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, Minneapolis, MN 55455 USA
| | - Antonio Suma
- grid.264727.20000 0001 2248 3398Department of Chemistry, Temple University, Philadelphia, PA 19122 USA
| | - Yungui He
- grid.17635.360000000419368657Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN 55455 USA
| | - Kenneth A. Matreyek
- grid.67105.350000 0001 2164 3847Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH 44106 USA
| | - Douglas M. Fowler
- grid.34477.330000000122986657Department of Genome Sciences, University of Washington, Seattle, WA 98115 USA ,grid.34477.330000000122986657Department of Bioengineering, University of Washington, Seattle, WA 98115 USA
| | - Vincenzo Carnevale
- grid.264727.20000 0001 2248 3398Department of Chemistry, Temple University, Philadelphia, PA 19122 USA
| | - Chad L. Myers
- grid.17635.360000000419368657Department of Computer Science and Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Daniel Schmidt
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN, 55455, USA.
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13
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Bali B, Lopez de la Morena D, Mittring A, Mager T, Rankovic V, Huet AT, Moser T. Utility of red-light ultrafast optogenetic stimulation of the auditory pathway. EMBO Mol Med 2021; 13:e13391. [PMID: 33960685 PMCID: PMC8185542 DOI: 10.15252/emmm.202013391] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 03/22/2021] [Accepted: 03/23/2021] [Indexed: 11/09/2022] Open
Abstract
Optogenetic stimulation of spiral ganglion neurons (SGNs) in the ear provides a future alternative to electrical stimulation used in current cochlear implants. Here, we employed fast and very fast variants of the red-light-activated channelrhodopsin (ChR) Chrimson (f-Chrimson and vf-Chrimson) to study their utility for optogenetic stimulation of SGNs in mice. The light requirements were higher for vf-Chrimson than for f-Chrimson, even when optimizing membrane expression of vf-Chrimson by adding potassium channel trafficking sequences. Optogenetic time and intensity coding by single putative SGNs were compared with coding of acoustic clicks. vf-Chrimson enabled putative SGNs to fire at near-physiological rates with good temporal precision up to 250 Hz of stimulation. The dynamic range of SGN spike rate coding upon optogenetic stimulation was narrower than for acoustic clicks but larger than reported for electrical stimulation. The dynamic range of spike timing, on the other hand, was more comparable for optogenetic and acoustic stimulation. In conclusion, f-Chrimson and vf-Chrimson are promising candidates for optogenetic stimulation of SGNs in auditory research and future cochlear implants.
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Affiliation(s)
- Burak Bali
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Göttingen Graduate School for Neurosciences and Molecular BiosciencesUniversity of GöttingenGöttingenGermany
- Restorative Cochlear Genomics GroupAuditory Neuroscience and Optogenetics LaboratoryGerman Primate CenterGöttingenGermany
| | - David Lopez de la Morena
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Göttingen Graduate School for Neurosciences and Molecular BiosciencesUniversity of GöttingenGöttingenGermany
- Auditory Neuroscience and Optogenetics LaboratoryGerman Primate CenterGöttingenGermany
- Auditory Neuroscience GroupMax‐Planck‐Institute for Experimental MedicineGöttingenGermany
| | - Artur Mittring
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Circuit LabInstitute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
| | - Thomas Mager
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC)University of GöttingenGöttingenGermany
| | - Vladan Rankovic
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Restorative Cochlear Genomics GroupAuditory Neuroscience and Optogenetics LaboratoryGerman Primate CenterGöttingenGermany
| | - Antoine Tarquin Huet
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Optogenetics LaboratoryGerman Primate CenterGöttingenGermany
- Auditory Circuit LabInstitute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC)University of GöttingenGöttingenGermany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Optogenetics LaboratoryGerman Primate CenterGöttingenGermany
- Auditory Neuroscience GroupMax‐Planck‐Institute for Experimental MedicineGöttingenGermany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC)University of GöttingenGöttingenGermany
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14
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Dong C, Ly C, Dunlap LE, Vargas MV, Sun J, Hwang IW, Azinfar A, Oh WC, Wetsel WC, Olson DE, Tian L. Psychedelic-inspired drug discovery using an engineered biosensor. Cell 2021; 184:2779-2792.e18. [PMID: 33915107 PMCID: PMC8122087 DOI: 10.1016/j.cell.2021.03.043] [Citation(s) in RCA: 95] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 02/28/2021] [Accepted: 03/19/2021] [Indexed: 02/07/2023]
Abstract
Ligands can induce G protein-coupled receptors (GPCRs) to adopt a myriad of conformations, many of which play critical roles in determining the activation of specific signaling cascades associated with distinct functional and behavioral consequences. For example, the 5-hydroxytryptamine 2A receptor (5-HT2AR) is the target of classic hallucinogens, atypical antipsychotics, and psychoplastogens. However, currently available methods are inadequate for directly assessing 5-HT2AR conformation both in vitro and in vivo. Here, we developed psychLight, a genetically encoded fluorescent sensor based on the 5-HT2AR structure. PsychLight detects behaviorally relevant serotonin release and correctly predicts the hallucinogenic behavioral effects of structurally similar 5-HT2AR ligands. We further used psychLight to identify a non-hallucinogenic psychedelic analog, which produced rapid-onset and long-lasting antidepressant-like effects after a single administration. The advent of psychLight will enable in vivo detection of serotonin dynamics, early identification of designer drugs of abuse, and the development of 5-HT2AR-dependent non-hallucinogenic therapeutics.
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Affiliation(s)
- Chunyang Dong
- Graduate Program in Biochemistry, Molecular, Cellular, Developmental Biology, University of California, Davis, Davis, CA 95616, USA; Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA, USA
| | - Calvin Ly
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Lee E Dunlap
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Maxemiliano V Vargas
- Neuroscience Graduate Program, University of California, Davis, Davis, CA 95618, USA
| | - Junqing Sun
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA, USA
| | - In-Wook Hwang
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Arya Azinfar
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Won Chan Oh
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - William C Wetsel
- Departments of Psychiatry and Behavioral Sciences, Cell Biology, and Neurobiology, Mouse Behavioral and Neuroendocrine Analysis Core Facility, Duke University Medical Center, Durham, NC 27710, USA
| | - David E Olson
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA; Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA, USA; Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA 95618, USA.
| | - Lin Tian
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA, USA; Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA 95618, USA.
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15
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Huet AT, Rankovic V. Application of Targeting-Optimized Chronos for Stimulation of the Auditory Pathway. Methods Mol Biol 2021; 2191:261-285. [PMID: 32865750 DOI: 10.1007/978-1-0716-0830-2_16] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
In the last 15 years, optogenetics has revolutionized the life sciences and enabled studies of complex biological systems such as the brain. Applying optogenetics also has great potential for restorative medicine, such as hearing restoration, by stimulating genetically modified spiral ganglion neurons of the cochlea with light. To this end, opsins with short closing kinetics are required, given the high firing rates and utmost temporal precision of spiking in these neurons. Chronos is the fastest native blue channelrhodopsin (ChR) reported so far with a closing kinetics bellow 1 ms at body temperature and an interesting candidate for the development of the future optogenetic cochlear implants. This book chapter explains in more details the development and application of Chronos with optimized membrane targeting for temporally precise optical stimulation of spiral ganglion neurons. In addition, the generation of adeno-associated virus (AAV) and AAV delivery to the cochlea of postnatal mice and the procedure to record optically evoked auditory brainstem responses are described.
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Affiliation(s)
- Antoine Tarquin Huet
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany
| | - Vladan Rankovic
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany. .,Restorative Cochlear Genomics Group, Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany.
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16
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Vevea JD, Chapman ER. Acute disruption of the synaptic vesicle membrane protein synaptotagmin 1 using knockoff in mouse hippocampal neurons. eLife 2020; 9:56469. [PMID: 32515733 PMCID: PMC7282819 DOI: 10.7554/elife.56469] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Accepted: 05/12/2020] [Indexed: 12/27/2022] Open
Abstract
The success of comparative cell biology for determining protein function relies on quality disruption techniques. Long-lived proteins, in postmitotic cells, are particularly difficult to eliminate. Moreover, cellular processes are notoriously adaptive; for example, neuronal synapses exhibit a high degree of plasticity. Ideally, protein disruption techniques should be both rapid and complete. Here, we describe knockoff, a generalizable method for the druggable control of membrane protein stability. We developed knockoff for neuronal use but show it also works in other cell types. Applying knockoff to synaptotagmin 1 (SYT1) results in acute disruption of this protein, resulting in loss of synchronous neurotransmitter release with a concomitant increase in the spontaneous release rate, measured optically. Thus, SYT1 is not only the proximal Ca2+ sensor for fast neurotransmitter release but also serves to clamp spontaneous release. Additionally, knockoff can be applied to protein domains as we show for another synaptic vesicle protein, synaptophysin 1.
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Affiliation(s)
- Jason D Vevea
- Department of Neuroscience, University of Wisconsin-Madison, Madison, United States.,Howard Hughes Medical Institute, Madison, United States
| | - Edwin R Chapman
- Department of Neuroscience, University of Wisconsin-Madison, Madison, United States.,Howard Hughes Medical Institute, Madison, United States
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17
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Walther F, Feind D, Vom Dahl C, Müller CE, Kukaj T, Sattler C, Nagel G, Gao S, Zimmer T. Action potentials in Xenopus oocytes triggered by blue light. J Gen Physiol 2020; 152:151581. [PMID: 32211871 PMCID: PMC7201882 DOI: 10.1085/jgp.201912489] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 02/24/2020] [Indexed: 11/20/2022] Open
Abstract
Voltage-gated sodium (Na+) channels are responsible for the fast upstroke of the action potential of excitable cells. The different α subunits of Na+ channels respond to brief membrane depolarizations above a threshold level by undergoing conformational changes that result in the opening of the pore and a subsequent inward flux of Na+. Physiologically, these initial membrane depolarizations are caused by other ion channels that are activated by a variety of stimuli such as mechanical stretch, temperature changes, and various ligands. In the present study, we developed an optogenetic approach to activate Na+ channels and elicit action potentials in Xenopus laevis oocytes. All recordings were performed by the two-microelectrode technique. We first coupled channelrhodopsin-2 (ChR2), a light-sensitive ion channel of the green alga Chlamydomonas reinhardtii, to the auxiliary β1 subunit of voltage-gated Na+ channels. The resulting fusion construct, β1-ChR2, retained the ability to modulate Na+ channel kinetics and generate photosensitive inward currents. Stimulation of Xenopus oocytes coexpressing the skeletal muscle Na+ channel Nav1.4 and β1-ChR2 with 25-ms lasting blue-light pulses resulted in rapid alterations of the membrane potential strongly resembling typical action potentials of excitable cells. Blocking Nav1.4 with tetrodotoxin prevented the fast upstroke and the reversal of the membrane potential. Coexpression of the voltage-gated K+ channel Kv2.1 facilitated action potential repolarization considerably. Light-induced action potentials were also obtained by coexpressing β1-ChR2 with either the neuronal Na+ channel Nav1.2 or the cardiac-specific isoform Nav1.5. Potential applications of this novel optogenetic tool are discussed.
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Affiliation(s)
- Florian Walther
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, Jena, Germany
| | - Dominic Feind
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, Jena, Germany
| | - Christian Vom Dahl
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, Jena, Germany
| | - Christoph Emanuel Müller
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, Jena, Germany
| | - Taulant Kukaj
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, Jena, Germany
| | - Christian Sattler
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, Jena, Germany
| | - Georg Nagel
- Institute of Physiology-Neurophysiology, Biocentre, Julius-Maximilians-University, Wuerzburg, Germany
| | - Shiqiang Gao
- Institute of Physiology-Neurophysiology, Biocentre, Julius-Maximilians-University, Wuerzburg, Germany
| | - Thomas Zimmer
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, Jena, Germany
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18
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Bradberry MM, Courtney NA, Dominguez MJ, Lofquist SM, Knox AT, Sutton RB, Chapman ER. Molecular Basis for Synaptotagmin-1-Associated Neurodevelopmental Disorder. Neuron 2020; 107:52-64.e7. [PMID: 32362337 DOI: 10.1016/j.neuron.2020.04.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 03/09/2020] [Accepted: 04/01/2020] [Indexed: 12/13/2022]
Abstract
At neuronal synapses, synaptotagmin-1 (syt1) acts as a Ca2+ sensor that synchronizes neurotransmitter release with Ca2+ influx during action potential firing. Heterozygous missense mutations in syt1 have recently been associated with a severe but heterogeneous developmental syndrome, termed syt1-associated neurodevelopmental disorder. Well-defined pathogenic mechanisms, and the basis for phenotypic heterogeneity in this disorder, remain unknown. Here, we report the clinical, physiological, and biophysical characterization of three syt1 mutations from human patients. Synaptic transmission was impaired in neurons expressing mutant variants, which demonstrated potent, graded dominant-negative effects. Biophysical interrogation of the mutant variants revealed novel mechanistic features concerning the cooperative action, and functional specialization, of the tandem Ca2+-sensing domains of syt1. These mechanistic studies led to the discovery that a clinically approved K+ channel antagonist is able to rescue the dominant-negative heterozygous phenotype. Our results establish a molecular cause, basis for phenotypic heterogeneity, and potential treatment approach for syt1-associated neurodevelopmental disorder.
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Affiliation(s)
- Mazdak M Bradberry
- Howard Hughes Medical Institute and Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA; Medical Scientist Training Program, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Nicholas A Courtney
- Howard Hughes Medical Institute and Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Matthew J Dominguez
- Department of Cell Physiology and Molecular Biophysics and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Sydney M Lofquist
- Howard Hughes Medical Institute and Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Andrew T Knox
- Department of Neurology, Section of Pediatric Neurology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - R Bryan Sutton
- Department of Cell Physiology and Molecular Biophysics and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Edwin R Chapman
- Howard Hughes Medical Institute and Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA.
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19
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Dieter A, Keppeler D, Moser T. Towards the optical cochlear implant: optogenetic approaches for hearing restoration. EMBO Mol Med 2020; 12:e11618. [PMID: 32227585 PMCID: PMC7136966 DOI: 10.15252/emmm.201911618] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 01/08/2020] [Accepted: 01/28/2020] [Indexed: 12/30/2022] Open
Abstract
Cochlear implants (CIs) are considered the most successful neuroprosthesis as they enable speech comprehension in the majority of half a million CI users suffering from sensorineural hearing loss. By electrically stimulating the auditory nerve, CIs constitute an interface re-connecting the brain and the auditory scene, providing the patient with information regarding the latter. However, since electric current is hard to focus in conductive environments such as the cochlea, the precision of electrical sound encoding-and thus quality of artificial hearing-is limited. Recently, optogenetic stimulation of the cochlea has been suggested as an alternative approach for hearing restoration. Cochlear optogenetics promises increased spectral selectivity of artificial sound encoding, hence improved hearing, as light can conveniently be confined in space to activate the auditory nerve within smaller tonotopic ranges. In this review, we discuss the latest experimental and technological developments of cochlear optogenetics and outline the remaining challenges on the way to clinical translation.
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Affiliation(s)
- Alexander Dieter
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Göttingen Graduate School for NeurosciencesBiophysics and Molecular BiosciencesUniversity of GöttingenGöttingenGermany
| | - Daniel Keppeler
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Optogenetics LaboratoryGerman Primate CenterGöttingenGermany
- Auditory Neuroscience GroupMax Planck Institute of Experimental MedicineGöttingenGermany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC)University of GöttingenGöttingenGermany
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20
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Ultrastructure of light-activated axons following optogenetic stimulation to produce late-phase long-term potentiation. PLoS One 2020; 15:e0226797. [PMID: 31940316 PMCID: PMC6961864 DOI: 10.1371/journal.pone.0226797] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 12/04/2019] [Indexed: 12/03/2022] Open
Abstract
Analysis of neuronal compartments has revealed many state-dependent changes in geometry but establishing synapse-specific mechanisms at the nanoscale has proven elusive. We co-expressed channelrhodopsin2-GFP and mAPEX2 in a subset of hippocampal CA3 neurons and used trains of light to induce late-phase long-term potentiation (L-LTP) in area CA1. L-LTP was shown to be specific to the labeled axons by severing CA3 inputs, which prevented back-propagating recruitment of unlabeled axons. Membrane-associated mAPEX2 tolerated microwave-enhanced chemical fixation and drove tyramide signal amplification to deposit Alexa Fluor dyes in the light-activated axons. Subsequent post-embedding immunogold labeling resulted in outstanding ultrastructure and clear distinctions between labeled (activated), and unlabeled axons without obscuring subcellular organelles. The gold-labeled axons in potentiated slices were reconstructed through serial section electron microscopy; presynaptic vesicles and other constituents could be quantified unambiguously. The genetic specification, reliable physiology, and compatibility with established methods for ultrastructural preservation make this an ideal approach to link synapse ultrastructure and function in intact circuits.
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21
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Zangerl-Plessl EM, Qile M, Bloothooft M, Stary-Weinzinger A, van der Heyden MAG. Disease Associated Mutations in K IR Proteins Linked to Aberrant Inward Rectifier Channel Trafficking. Biomolecules 2019; 9:biom9110650. [PMID: 31731488 PMCID: PMC6920955 DOI: 10.3390/biom9110650] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 10/22/2019] [Accepted: 10/23/2019] [Indexed: 12/28/2022] Open
Abstract
The ubiquitously expressed family of inward rectifier potassium (KIR) channels, encoded by KCNJ genes, is primarily involved in cell excitability and potassium homeostasis. Channel mutations associate with a variety of severe human diseases and syndromes, affecting many organ systems including the central and peripheral neural system, heart, kidney, pancreas, and skeletal muscle. A number of mutations associate with altered ion channel expression at the plasma membrane, which might result from defective channel trafficking. Trafficking involves cellular processes that transport ion channels to and from their place of function. By alignment of all KIR channels, and depicting the trafficking associated mutations, three mutational hotspots were identified. One localized in the transmembrane-domain 1 and immediately adjacent sequences, one was found in the G-loop and Golgi-export domain, and the third one was detected at the immunoglobulin-like domain. Surprisingly, only few mutations were observed in experimentally determined Endoplasmic Reticulum (ER)exit-, export-, or ER-retention motifs. Structural mapping of the trafficking defect causing mutations provided a 3D framework, which indicates that trafficking deficient mutations form clusters. These “mutation clusters” affect trafficking by different mechanisms, including protein stability.
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Affiliation(s)
- Eva-Maria Zangerl-Plessl
- Department of Pharmacology and Toxicology, University of Vienna, 1090 Vienna, Austria; (E.-M.Z.-P.); (A.S.-W.)
| | - Muge Qile
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, 3584 CM Utrecht, The Netherlands; (M.Q.); (M.B.)
| | - Meye Bloothooft
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, 3584 CM Utrecht, The Netherlands; (M.Q.); (M.B.)
| | - Anna Stary-Weinzinger
- Department of Pharmacology and Toxicology, University of Vienna, 1090 Vienna, Austria; (E.-M.Z.-P.); (A.S.-W.)
| | - Marcel A. G. van der Heyden
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, 3584 CM Utrecht, The Netherlands; (M.Q.); (M.B.)
- Correspondence: ; Tel.: +31-887558901
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22
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Sengupta S, Rothenberg KE, Li H, Hoffman BD, Bursac N. Altering integrin engagement regulates membrane localization of K ir2.1 channels. J Cell Sci 2019; 132:jcs225383. [PMID: 31391240 PMCID: PMC6771140 DOI: 10.1242/jcs.225383] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 07/31/2019] [Indexed: 12/26/2022] Open
Abstract
How ion channels localize and distribute on the cell membrane remains incompletely understood. We show that interventions that vary cell adhesion proteins and cell size also affect the membrane current density of inward-rectifier K+ channels (Kir2.1; encoded by KCNJ2) and profoundly alter the action potential shape of excitable cells. By using micropatterning to manipulate the localization and size of focal adhesions (FAs) in single HEK293 cells engineered to stably express Kir2.1 channels or in neonatal rat cardiomyocytes, we establish a robust linear correlation between FA coverage and the amplitude of Kir2.1 current at both the local and whole-cell levels. Confocal microscopy showed that Kir2.1 channels accumulate in membrane proximal to FAs. Selective pharmacological inhibition of key mediators of protein trafficking and the spatially dependent alterations in the dynamics of Kir2.1 fluorescent recovery after photobleaching revealed that the Kir2.1 channels are transported to the cell membrane uniformly, but are preferentially internalized by endocytosis at sites that are distal from FAs. Based on these results, we propose adhesion-regulated membrane localization of ion channels as a fundamental mechanism of controlling cellular electrophysiology via mechanochemical signals, independent of the direct ion channel mechanogating.
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Affiliation(s)
- Swarnali Sengupta
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | | | - Hanjun Li
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Brenton D Hoffman
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Nenad Bursac
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
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23
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Dombrowski T, Rankovic V, Moser T. Toward the Optical Cochlear Implant. Cold Spring Harb Perspect Med 2019; 9:cshperspect.a033225. [PMID: 30323016 DOI: 10.1101/cshperspect.a033225] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
When hearing fails, cochlear implants (CIs) provide open speech perception to most of the currently half a million CI users. CIs bypass the defective sensory organ and stimulate the auditory nerve electrically. The major bottleneck of current CIs is the poor coding of spectral information, which results from wide current spread from each electrode contact. As light can be more conveniently confined, optical stimulation of the auditory nerve presents a promising perspective for a fundamental advance of CIs. Moreover, given the improved frequency resolution of optical excitation and its versatility for arbitrary stimulation patterns the approach also bears potential for auditory research. Here, we review the current state of the art focusing on the emerging concept of optogenetic stimulation of the auditory pathway. Developing optogenetic stimulation for auditory research and future CIs requires efforts toward viral gene transfer to the neurons, design and characterization of appropriate optogenetic actuators, as well as engineering of multichannel optical implants.
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Affiliation(s)
- Tobias Dombrowski
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center, 37075 Göttingen, Germany.,Department of Otorhinolaryngology, Head and Neck Surgery, Ruhr University Bochum, St. Elisabeth Hospital, 44787 Bochum, Germany
| | - Vladan Rankovic
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center, 37075 Göttingen, Germany.,Auditory Neuroscience and Optogenetics Group, German Primate Center, 37077 Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center, 37075 Göttingen, Germany.,Auditory Neuroscience and Optogenetics Group, German Primate Center, 37077 Göttingen, Germany.,Auditory Neuroscience Group, Max-Planck-Institute for Experimental Medicine, 37075 Göttingen, Germany
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24
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Qile M, Ji Y, Houtman MJC, Veldhuis M, Romunde F, Kok B, van der Heyden MAG. Identification of a PEST Sequence in Vertebrate K IR2.1 That Modifies Rectification. Front Physiol 2019; 10:863. [PMID: 31333502 PMCID: PMC6624654 DOI: 10.3389/fphys.2019.00863] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 06/20/2019] [Indexed: 11/13/2022] Open
Abstract
KIR2.1 potassium channels, producing inward rectifier potassium current (IK1), are important for final action potential repolarization and a stable resting membrane potential in excitable cells like cardiomyocytes. Abnormal KIR2.1 function, either decreased or increased, associates with diseases such as Andersen-Tawil syndrome, long and short QT syndromes. KIR2.1 ion channel protein trafficking and subcellular anchoring depends on intrinsic specific short amino acid sequences. We hypothesized that combining an evolutionary based sequence comparison and bioinformatics will identify new functional domains within the C-terminus of the KIR2.1 protein, which function could be determined by mutation analysis. We determined PEST domain signatures, rich in proline (P), glutamic acid (E), serine (S), and threonine (T), within KIR2.1 sequences using the “epestfind” webtool. WT and ΔPEST KIR2.1 channels were expressed in HEK293T and COS-7 cells. Patch-clamp electrophysiology measurements were performed in the inside-out mode on excised membrane patches and the whole cell mode using AxonPatch 200B amplifiers. KIR2.1 protein expression levels were determined by western blot analysis. Immunofluorescence microscopy was used to determine KIR2.1 subcellular localization. An evolutionary conserved PEST domain was identified in the C-terminus of the KIR2.1 channel protein displaying positive PEST scores in vertebrates ranging from fish to human. No similar PEST domain was detected in KIR2.2, KIR2.3, and KIR2.6 proteins. Deletion of the PEST domain in California kingsnake and human KIR2.1 proteins (ΔPEST), did not affect plasma membrane localization. Co-expression of WT and ΔPEST KIR2.1 proteins resulted in heterotetrameric channel formation. Deletion of the PEST domain did not increase protein stability in cycloheximide assays [T½ from 2.64 h (WT) to 1.67 h (ΔPEST), n.s.]. WT and ΔPEST channels, either from human or snake, produced typical IK1, however, human ΔPEST channels displayed stronger intrinsic rectification. The current observations suggest that the PEST sequence of KIR2.1 is not associated with rapid protein degradation, and has a role in the rectification behavior of IK1 channels.
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Affiliation(s)
- Muge Qile
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Yuan Ji
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Marien J C Houtman
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Marlieke Veldhuis
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Fee Romunde
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Bart Kok
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Marcel A G van der Heyden
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
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25
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Abstract
All proteins end with a carboxyl terminus that has unique biophysical properties and is often disordered. Although there are examples of important C-termini functions, a more global role for the C-terminus is not yet established. In this review, we summarize research on C-termini, a unique region in proteins that cells exploit. Alternative splicing and proteolysis increase the diversity of proteins and peptides in cells with unique C-termini. The C-termini of proteins contain minimotifs, short peptides with an encoded function generally characterized as binding, posttranslational modifications, and trafficking. Many of these activities are specific to minimotifs on the C-terminus. Approximately 13% of C-termini in the human proteome have a known minimotif, and the majority, if not all of the remaining termini have conserved motifs inferring a function that remains to be discovered. C-termini, their predictions, and their functions are collated in the C-terminome, Proteus, and Terminus Oriented Protein Function INferred Database (TopFIND) database/web systems. Many C-termini are well conserved, and some have a known role in health and disease. We envision that this summary of C-termini will guide future investigation of their biochemical and physiological significance.
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Affiliation(s)
- Surbhi Sharma
- a Nevada Institute of Personalized Medicine and School of Life Sciences , University of Nevada , Las Vegas , NV , USA
| | - Martin R Schiller
- a Nevada Institute of Personalized Medicine and School of Life Sciences , University of Nevada , Las Vegas , NV , USA
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26
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Coyote-Maestas W, He Y, Myers CL, Schmidt D. Domain insertion permissibility-guided engineering of allostery in ion channels. Nat Commun 2019; 10:290. [PMID: 30655517 PMCID: PMC6336875 DOI: 10.1038/s41467-018-08171-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 12/17/2018] [Indexed: 01/01/2023] Open
Abstract
Allostery is a fundamental principle of protein regulation that remains hard to engineer, particularly in membrane proteins such as ion channels. Here we use human Inward Rectifier K+ Channel Kir2.1 to map site-specific permissibility to the insertion of domains with different biophysical properties. We find that permissibility is best explained by dynamic protein properties, such as conformational flexibility. Several regions in Kir2.1 that are equivalent to those regulated in homologs, such as G-protein-gated inward rectifier K+ channels (GIRK), have differential permissibility; that is, for these sites permissibility depends on the structural properties of the inserted domain. Our data and the well-established link between protein dynamics and allostery led us to propose that differential permissibility is a metric of latent allosteric capacity in Kir2.1. In support of this notion, inserting light-switchable domains into sites with predicted latent allosteric capacity renders Kir2.1 activity sensitive to light. Allostery is a fundamental principle of protein regulation that remains challenging to engineer. Here authors screen human Inward Rectifier K + Channel Kir2.1 for permissibility to domain insertions and propose that differential permissibility is a metric of latent allosteric capacity in Kir2.1.
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Affiliation(s)
- Willow Coyote-Maestas
- Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, Minneapolis, 55455, MN, USA
| | - Yungui He
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, 55455, MN, USA
| | - Chad L Myers
- Department of Computer Science and Engineering, University of Minnesota, Minneapolis, 55455, MN, USA
| | - Daniel Schmidt
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, 55455, MN, USA.
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27
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Keppeler D, Merino RM, Lopez de la Morena D, Bali B, Huet AT, Gehrt A, Wrobel C, Subramanian S, Dombrowski T, Wolf F, Rankovic V, Neef A, Moser T. Ultrafast optogenetic stimulation of the auditory pathway by targeting-optimized Chronos. EMBO J 2018; 37:embj.201899649. [PMID: 30396994 DOI: 10.15252/embj.201899649] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 09/25/2018] [Accepted: 09/28/2018] [Indexed: 12/16/2022] Open
Abstract
Optogenetic tools, providing non-invasive control over selected cells, have the potential to revolutionize sensory prostheses for humans. Optogenetic stimulation of spiral ganglion neurons (SGNs) in the ear provides a future alternative to electrical stimulation used in cochlear implants. However, most channelrhodopsins do not support the high temporal fidelity pertinent to auditory coding because they require milliseconds to close after light-off. Here, we biophysically characterized the fast channelrhodopsin Chronos and revealed a deactivation time constant of less than a millisecond at body temperature. In order to enhance neural expression, we improved its trafficking to the plasma membrane (Chronos-ES/TS). Following efficient transduction of SGNs using early postnatal injection of the adeno-associated virus AAV-PHPB into the mouse cochlea, fiber-based optical stimulation elicited optical auditory brainstem responses (oABR) with minimal latencies of 1 ms, thresholds of 5 μJ and 100 μs per pulse, and sizable amplitudes even at 1,000 Hz of stimulation. Recordings from single SGNs demonstrated good temporal precision of light-evoked spiking. In conclusion, efficient virus-mediated expression of targeting-optimized Chronos-ES/TS achieves ultrafast optogenetic control of neurons.
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Affiliation(s)
- Daniel Keppeler
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Göttingen Graduate School for Neurosciences and Molecular Biosciences, University of Göttingen, Göttingen, Germany
| | - Ricardo Martins Merino
- Göttingen Graduate School for Neurosciences and Molecular Biosciences, University of Göttingen, Göttingen, Germany.,Biophysics of Neural Computation Group, Bernstein Center for Computational Neuroscience Göttingen, Göttingen, Germany.,Neurophysics Group, Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany.,Max Planck Institute for Experimental Medicine, Göttingen, Germany
| | - David Lopez de la Morena
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Göttingen Graduate School for Neurosciences and Molecular Biosciences, University of Göttingen, Göttingen, Germany.,Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany
| | - Burak Bali
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Göttingen Graduate School for Neurosciences and Molecular Biosciences, University of Göttingen, Göttingen, Germany.,Restorative Cochlear Genomics Group, German Primate Center, Göttingen, Germany
| | - Antoine Tarquin Huet
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Biophysics of Neural Computation Group, Bernstein Center for Computational Neuroscience Göttingen, Göttingen, Germany.,Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany
| | - Anna Gehrt
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
| | - Christian Wrobel
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
| | - Swati Subramanian
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Göttingen Graduate School for Neurosciences and Molecular Biosciences, University of Göttingen, Göttingen, Germany
| | - Tobias Dombrowski
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Fred Wolf
- Neurophysics Group, Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany.,Max Planck Institute for Experimental Medicine, Göttingen, Germany.,Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.,Bernstein Center for Computational Neuroscience, Göttingen, Germany.,Campus Institute for Dynamics of Biological Networks, Göttingen, Germany
| | - Vladan Rankovic
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany .,Restorative Cochlear Genomics Group, German Primate Center, Göttingen, Germany
| | - Andreas Neef
- Biophysics of Neural Computation Group, Bernstein Center for Computational Neuroscience Göttingen, Göttingen, Germany .,Neurophysics Group, Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany.,Campus Institute for Dynamics of Biological Networks, Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany .,Göttingen Graduate School for Neurosciences and Molecular Biosciences, University of Göttingen, Göttingen, Germany.,Biophysics of Neural Computation Group, Bernstein Center for Computational Neuroscience Göttingen, Göttingen, Germany.,Max Planck Institute for Experimental Medicine, Göttingen, Germany.,Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany.,Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.,Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Göttingen, Germany
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28
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Soloperto A, Boccaccio A, Contestabile A, Moroni M, Hallinan GI, Palazzolo G, Chad J, Deinhardt K, Carugo D, Difato F. Mechano-sensitization of mammalian neuronal networks through expression of the bacterial large-conductance mechanosensitive ion channel. J Cell Sci 2018; 131:jcs210393. [PMID: 29361543 PMCID: PMC5897719 DOI: 10.1242/jcs.210393] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 01/13/2018] [Indexed: 12/11/2022] Open
Abstract
Development of remote stimulation techniques for neuronal tissues represents a challenging goal. Among the potential methods, mechanical stimuli are the most promising vectors to convey information non-invasively into intact brain tissue. In this context, selective mechano-sensitization of neuronal circuits would pave the way to develop a new cell-type-specific stimulation approach. We report here, for the first time, the development and characterization of mechano-sensitized neuronal networks through the heterologous expression of an engineered bacterial large-conductance mechanosensitive ion channel (MscL). The neuronal functional expression of the MscL was validated through patch-clamp recordings upon application of calibrated suction pressures. Moreover, we verified the effective development of in-vitro neuronal networks expressing the engineered MscL in terms of cell survival, number of synaptic puncta and spontaneous network activity. The pure mechanosensitivity of the engineered MscL, with its wide genetic modification library, may represent a versatile tool to further develop a mechano-genetic approach.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Alessandro Soloperto
- Neuroscience and Brain Technologies Dept., Istituto Italiano di Tecnologia, 16163 Genoa, Italy
| | - Anna Boccaccio
- Institute of Biophysics, National Research Council of Italy, 16149 Genoa, Italy
| | - Andrea Contestabile
- Neuroscience and Brain Technologies Dept., Istituto Italiano di Tecnologia, 16163 Genoa, Italy
| | - Monica Moroni
- Center for Neuroscience and Cognitive Systems, Istituto Italiano di Tecnologia, 38068 Rovereto, Italy
| | - Grace I Hallinan
- Biological Sciences and Institute for Life Sciences, University of Southampton, SO17 1BJ Southampton, UK
| | - Gemma Palazzolo
- Neuroscience and Brain Technologies Dept., Istituto Italiano di Tecnologia, 16163 Genoa, Italy
| | - John Chad
- Biological Sciences and Institute for Life Sciences, University of Southampton, SO17 1BJ Southampton, UK
| | - Katrin Deinhardt
- Biological Sciences and Institute for Life Sciences, University of Southampton, SO17 1BJ Southampton, UK
| | - Dario Carugo
- Faculty of Engineering and the Environment, University of Southampton, SO17 1BJ Southampton, UK
| | - Francesco Difato
- Neuroscience and Brain Technologies Dept., Istituto Italiano di Tecnologia, 16163 Genoa, Italy
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29
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Ponce-Balbuena D, Guerrero-Serna G, Valdivia CR, Caballero R, Diez-Guerra FJ, Jiménez-Vázquez EN, Ramírez RJ, Monteiro da Rocha A, Herron TJ, Campbell KF, Willis BC, Alvarado FJ, Zarzoso M, Kaur K, Pérez-Hernández M, Matamoros M, Valdivia HH, Delpón E, Jalife J. Cardiac Kir2.1 and Na V1.5 Channels Traffic Together to the Sarcolemma to Control Excitability. Circ Res 2018. [PMID: 29514831 DOI: 10.1161/circresaha.117.311872] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
RATIONALE In cardiomyocytes, NaV1.5 and Kir2.1 channels interact dynamically as part of membrane bound macromolecular complexes. OBJECTIVE The objective of this study was to test whether NaV1.5 and Kir2.1 preassemble during early forward trafficking and travel together to common membrane microdomains. METHODS AND RESULTS In patch-clamp experiments, coexpression of trafficking-deficient mutants Kir2.1Δ314-315 or Kir2.1R44A/R46A with wild-type (WT) NaV1.5WT in heterologous cells reduced inward sodium current compared with NaV1.5WT alone or coexpressed with Kir2.1WT. In cell surface biotinylation experiments, expression of Kir2.1Δ314-315 reduced NaV1.5 channel surface expression. Glycosylation analysis suggested that NaV1.5WT and Kir2.1WT channels associate early in their biosynthetic pathway, and fluorescence recovery after photobleaching experiments demonstrated that coexpression with Kir2.1 increased cytoplasmic mobility of NaV1.5WT, and vice versa, whereas coexpression with Kir2.1Δ314-315 reduced mobility of both channels. Viral gene transfer of Kir2.1Δ314-315 in adult rat ventricular myocytes and human induced pluripotent stem cell-derived cardiomyocytes reduced inward rectifier potassium current and inward sodium current, maximum diastolic potential and action potential depolarization rate, and increased action potential duration. On immunostaining, the AP1 (adaptor protein complex 1) colocalized with NaV1.5WT and Kir2.1WT within areas corresponding to t-tubules and intercalated discs. Like Kir2.1WT, NaV1.5WT coimmunoprecipitated with AP1. Site-directed mutagenesis revealed that NaV1.5WT channels interact with AP1 through the NaV1.5Y1810 residue, suggesting that, like for Kir2.1WT, AP1 can mark NaV1.5 channels for incorporation into clathrin-coated vesicles at the trans-Golgi. Silencing the AP1 ϒ-adaptin subunit in human induced pluripotent stem cell-derived cardiomyocytes reduced inward rectifier potassium current, inward sodium current, and maximum diastolic potential and impaired rate-dependent action potential duration adaptation. CONCLUSIONS The NaV1.5-Kir2.1 macromolecular complex pre-assembles early in the forward trafficking pathway. Therefore, disruption of Kir2.1 trafficking in cardiomyocytes affects trafficking of NaV1.5, which may have important implications in the mechanisms of arrhythmias in inheritable cardiac diseases.
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Affiliation(s)
- Daniela Ponce-Balbuena
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - Guadalupe Guerrero-Serna
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - Carmen R Valdivia
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - Ricardo Caballero
- Department of Pharmacology, School of Medicine, Universidad Complutense, Madrid, Spain (R.C., M.P.-H., M.M., E.D.).,Instituto de Investigación Sanitaria Gregorio Marañón, School of Medicine, Universidad Complutense, Madrid, Spain (R.C., M.P.-H., M.M., E.D.)
| | - F Javier Diez-Guerra
- Departamento de Biología Molecular and Centro de Biología Molecular Severo Ochoa (UAM-CSIC), Universidad Autónoma de Madrid, Spain (F.J.D.-G.)
| | - Eric N Jiménez-Vázquez
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - Rafael J Ramírez
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - André Monteiro da Rocha
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - Todd J Herron
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - Katherine F Campbell
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - B Cicero Willis
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | | | - Manuel Zarzoso
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - Kuljeet Kaur
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - Marta Pérez-Hernández
- Department of Pharmacology, School of Medicine, Universidad Complutense, Madrid, Spain (R.C., M.P.-H., M.M., E.D.).,Instituto de Investigación Sanitaria Gregorio Marañón, School of Medicine, Universidad Complutense, Madrid, Spain (R.C., M.P.-H., M.M., E.D.)
| | - Marcos Matamoros
- Department of Pharmacology, School of Medicine, Universidad Complutense, Madrid, Spain (R.C., M.P.-H., M.M., E.D.).,Instituto de Investigación Sanitaria Gregorio Marañón, School of Medicine, Universidad Complutense, Madrid, Spain (R.C., M.P.-H., M.M., E.D.)
| | - Héctor H Valdivia
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.).,Department of Molecular and Integrative Physiology (F.J.A., H.H.V.)
| | - Eva Delpón
- Department of Pharmacology, School of Medicine, Universidad Complutense, Madrid, Spain (R.C., M.P.-H., M.M., E.D.).,Instituto de Investigación Sanitaria Gregorio Marañón, School of Medicine, Universidad Complutense, Madrid, Spain (R.C., M.P.-H., M.M., E.D.)
| | - José Jalife
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.) .,University of Michigan, Ann Arbor; Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain (J.J.).,CIBERV, Madrid, Spain (J.J.)
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Bridges RJ, Bradbury NA. Cystic Fibrosis, Cystic Fibrosis Transmembrane Conductance Regulator and Drugs: Insights from Cellular Trafficking. Handb Exp Pharmacol 2018; 245:385-425. [PMID: 29460152 DOI: 10.1007/164_2018_103] [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] [Indexed: 02/06/2023]
Abstract
The eukaryotic cell is organized into membrane-delineated compartments that are characterized by specific cadres of proteins sustaining biochemically distinct cellular processes. The appropriate subcellular localization of proteins is key to proper organelle function and provides a physiological context for cellular processes. Disruption of normal trafficking pathways for proteins is seen in several genetic diseases, where a protein's absence for a specific subcellular compartment leads to organelle disruption, and in the context of an individual, a disruption of normal physiology. Importantly, several drug therapies can also alter protein trafficking, causing unwanted side effects. Thus, a deeper understanding of trafficking pathways needs to be appreciated as novel therapeutic modalities are proposed. Despite the promising efficacy of novel therapeutic agents, the intracellular bioavailability of these compounds has proved to be a potential barrier, leading to failures in treatments for various diseases and disorders. While endocytosis of drug moieties provides an efficient means of getting material into cells, the subsequent release and endosomal escape of materials into the cytosol where they need to act has been a barrier. An understanding of cellular protein/lipid trafficking pathways has opened up strategies for increasing drug bioavailability. Approaches to enhance endosomal exit have greatly increased the cytosolic bioavailability of drugs and will provide a means of investigating previous drugs that may have been shelved due to their low cytosolic concentration.
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Affiliation(s)
- Robert J Bridges
- Department of Physiology and Biophysics, Chicago Medical School, North Chicago, IL, USA
| | - Neil A Bradbury
- Department of Physiology and Biophysics, Chicago Medical School, North Chicago, IL, USA.
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Leem YE, Jeong HJ, Kim HJ, Koh J, Kang K, Bae GU, Cho H, Kang JS. Cdo Regulates Surface Expression of Kir2.1 K+ Channel in Myoblast Differentiation. PLoS One 2016; 11:e0158707. [PMID: 27380411 PMCID: PMC4933383 DOI: 10.1371/journal.pone.0158707] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 06/21/2016] [Indexed: 01/28/2023] Open
Abstract
A potassium channel Kir2.1-associated membrane hyperpolarization is required for myogenic differentiation. However the molecular regulatory mechanisms modulating Kir2.1 channel activities in early stage of myogenesis are largely unknown. A cell surface protein, Cdo functions as a component of multiprotein cell surface complexes to promote myogenesis. In this study, we report that Cdo forms a complex with Kir2.1 during myogenic differentiation, and is required for the channel activity by enhancing the surface expression of Kir2.1 in the early stage of differentiation. The expression of a constitutively active form of the upstream kinase for p38MAPK, MKK6(EE) can restore Kir2.1 activities in Cdo-depleted C2C12 cells, while the treatment with a p38MAPK inhibitor, SB203580 exhibits a similar effect of Cdo depletion on Kir2.1 surface expression. Furthermore, Cdo-/- primary myoblasts, which display a defective differentiation program, exhibit a defective Kir2.1 activity. Taken together, our results suggest that a promyogenic Cdo signaling is critical for Kir2.1 activities in the induction of myogenic differentiation.
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Affiliation(s)
- Young-Eun Leem
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
- Samsung Biomedical Research Institute, Suwon, Republic of Korea
| | - Hyeon-Ju Jeong
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
- Samsung Biomedical Research Institute, Suwon, Republic of Korea
| | - Hyun-Ji Kim
- Department of Physiology, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
- Samsung Biomedical Research Institute, Suwon, Republic of Korea
| | - Jewoo Koh
- Department of Physiology, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
- Samsung Biomedical Research Institute, Suwon, Republic of Korea
| | - KyeongJin Kang
- Department of Anatomy, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
- Samsung Biomedical Research Institute, Suwon, Republic of Korea
| | - Gyu-Un Bae
- Research Center for Cell Fate Control, Sookmyung Women’s University, Seoul, Republic of Korea
| | - Hana Cho
- Department of Physiology, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
- Samsung Biomedical Research Institute, Suwon, Republic of Korea
- * E-mail: (JSK); (HC)
| | - Jong-Sun Kang
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
- Samsung Biomedical Research Institute, Suwon, Republic of Korea
- * E-mail: (JSK); (HC)
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Akemann W, Song C, Mutoh H, Knöpfel T. Route to genetically targeted optical electrophysiology: development and applications of voltage-sensitive fluorescent proteins. NEUROPHOTONICS 2015; 2:021008. [PMID: 26082930 PMCID: PMC4465821 DOI: 10.1117/1.nph.2.2.021008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 12/11/2014] [Indexed: 06/04/2023]
Abstract
The invention of membrane voltage protein indicators widens the reach of optical voltage imaging in cell physiology, most notably neurophysiology, by enabling membrane voltage recordings from genetically defined cell types in chronic and life-long preparations. While the last years have seen a dramatic improvement in the technical performance of these indicators, concomitant innovations in optogenetics, optical axon tracing, and high-speed digital microscopy are beginning to fulfill the age-old vision of an all-optical analysis of neuronal circuits, reaching beyond the limits of traditional electrode-based recordings. We will present our personal account of the development of protein voltage indicators from the pioneering days to the present state, including their applications in neurophysiology that has inspired our own work for more than a decade.
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Affiliation(s)
- Walther Akemann
- Imperial College London, Department of Medicine, London W12 ONN, United Kingdom
- Institute of Biology, CNRS UMR 8197, École Normale Supérieure, 46 rue d’Ulm, 75005 Paris, France
| | - Chenchen Song
- Imperial College London, Department of Medicine, London W12 ONN, United Kingdom
| | - Hiroki Mutoh
- Hamamatsu University School of Medicine, Department of Neurophysiology, Shizuoka 431-3192, Japan
| | - Thomas Knöpfel
- Imperial College London, Department of Medicine, London W12 ONN, United Kingdom
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Insights in KIR2.1 channel structure and function by an evolutionary approach; cloning and functional characterization of the first reptilian inward rectifier channel KIR2.1, derived from the California kingsnake (Lampropeltis getula californiae). Biochem Biophys Res Commun 2014; 452:992-7. [DOI: 10.1016/j.bbrc.2014.09.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 09/08/2014] [Indexed: 11/21/2022]
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Independent optical excitation of distinct neural populations. Nat Methods 2014; 11:338-46. [PMID: 24509633 PMCID: PMC3943671 DOI: 10.1038/nmeth.2836] [Citation(s) in RCA: 1372] [Impact Index Per Article: 137.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 01/10/2014] [Indexed: 11/08/2022]
Abstract
Optogenetic tools enable examination of how specific cell types contribute to brain circuit functions. A long-standing question is whether it is possible to independently activate two distinct neural populations in mammalian brain tissue. Such a capability would enable the study of how different synapses or pathways interact to encode information in the brain. Here we describe two channelrhodopsins, Chronos and Chrimson, discovered through sequencing and physiological characterization of opsins from over 100 species of alga. Chrimson's excitation spectrum is red shifted by 45 nm relative to previous channelrhodopsins and can enable experiments in which red light is preferred. We show minimal visual system-mediated behavioral interference when using Chrimson in neurobehavioral studies in Drosophila melanogaster. Chronos has faster kinetics than previous channelrhodopsins yet is effectively more light sensitive. Together these two reagents enable two-color activation of neural spiking and downstream synaptic transmission in independent neural populations without detectable cross-talk in mouse brain slice.
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Lin YC, Chen BM, Lu WC, Su CI, Prijovich ZM, Chung WC, Wu PY, Chen KC, Lee IC, Juan TY, Roffler SR. The B7-1 cytoplasmic tail enhances intracellular transport and mammalian cell surface display of chimeric proteins in the absence of a linear ER export motif. PLoS One 2013; 8:e75084. [PMID: 24073236 PMCID: PMC3779271 DOI: 10.1371/journal.pone.0075084] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 08/12/2013] [Indexed: 11/18/2022] Open
Abstract
Membrane-tethered proteins (mammalian surface display) are increasingly being used for novel therapeutic and biotechnology applications. Maximizing surface expression of chimeric proteins on mammalian cells is important for these applications. We show that the cytoplasmic domain from the B7-1 antigen, a commonly used element for mammalian surface display, can enhance the intracellular transport and surface display of chimeric proteins in a Sar1 and Rab1 dependent fashion. However, mutational, alanine scanning and deletion analysis demonstrate the absence of linear ER export motifs in the B7 cytoplasmic domain. Rather, efficient intracellular transport correlated with the presence of predicted secondary structure in the cytoplasmic tail. Examination of the cytoplasmic domains of 984 human and 782 mouse type I transmembrane proteins revealed that many previously identified ER export motifs are rarely found in the cytoplasmic tail of type I transmembrane proteins. Our results suggest that efficient intracellular transport of B7 chimeric proteins is associated with the structure rather than to the presence of a linear ER export motif in the cytoplasmic tail, and indicate that short (less than ~ 10-20 amino acids) and unstructured cytoplasmic tails should be avoided to express high levels of chimeric proteins on mammalian cells.
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Affiliation(s)
- Yi-Chieh Lin
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Bing-Mae Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Wei-Cheng Lu
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chien-I Su
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | | | - Wen-Chuan Chung
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Pei-Yu Wu
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Kai-Chuan Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - I-Chiao Lee
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Ting-Yi Juan
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Steve R. Roffler
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
- * E-mail:
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The degradation of the inwardly rectifying potassium channel, Kir2.1, depends on the expression level: examination with fluorescent proteins. Brain Res 2013; 1528:8-19. [PMID: 23850646 DOI: 10.1016/j.brainres.2013.07.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2012] [Revised: 07/01/2013] [Accepted: 07/05/2013] [Indexed: 01/24/2023]
Abstract
The expression of ion channels is regulated by their synthesis as well as degradation, and some ion channels are degraded in an expression level-dependent way. Recently, new techniques of fluorescent proteins have been developed and seem to be useful to study protein degradation. To examine the regulation of the degradation of strongly inwardly rectifying potassium channel (Kir2.1) and the usefulness of the fluorescent proteins, we constructed Kir2.1 fusion proteins with SNAP tag and fluorescent timer (FT). The SNAP tag, which covalently binds to a specific membrane-permeable fluorescent dye, enables a pulse-chase experiment with fluorescence. When the SNAP-Kir2.1 proteins were expressed in 293T cells by low and high expression plasmids, the half-life of the fusion protein expressed by a high-expression plasmid was shorter (18.2±1.9 h) than that expressed by a low-expression plasmid (35.1+2.3h). The addition of Ba(2+), a selective blocker of Kir2.1, slowed the degradation, suggesting a current-dependency of degradation. Consistently, patch-clamp recording showed that cultivation in the presence of Ba(2+) increased the whole cell conductance of SNAP-Kir2.1. Since the fluorescence of FT changes gradually changes from green to red, the green/red ratio should allow us to monitor the changes in the degradation rate of FT-Kir2.1. Using this method, we confirmed the slower degradation by Ba(2+). The results suggest a homeostatic regulation of the degradation of Kir2.1 in the 293T cells, and the usefulness of fluorescence-based methods for examining the degradation of ion channels.
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Inhibiting the clathrin-mediated endocytosis pathway rescues KIR2.1 downregulation by pentamidine. Pflugers Arch 2012. [DOI: 10.1007/s00424-012-1189-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Balse E, Steele DF, Abriel H, Coulombe A, Fedida D, Hatem SN. Dynamic of Ion Channel Expression at the Plasma Membrane of Cardiomyocytes. Physiol Rev 2012; 92:1317-58. [DOI: 10.1152/physrev.00041.2011] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cardiac myocytes are characterized by distinct structural and functional entities involved in the generation and transmission of the action potential and the excitation-contraction coupling process. Key to their function is the specific organization of ion channels and transporters to and within distinct membrane domains, which supports the anisotropic propagation of the depolarization wave. This review addresses the current knowledge on the molecular actors regulating the distinct trafficking and targeting mechanisms of ion channels in the highly polarized cardiac myocyte. In addition to ubiquitous mechanisms shared by other excitable cells, cardiac myocytes show unique specialization, illustrated by the molecular organization of myocyte-myocyte contacts, e.g., the intercalated disc and the gap junction. Many factors contribute to the specialization of the cardiac sarcolemma and the functional expression of cardiac ion channels, including various anchoring proteins, motors, small GTPases, membrane lipids, and cholesterol. The discovery of genetic defects in some of these actors, leading to complex cardiac disorders, emphasizes the importance of trafficking and targeting of ion channels to cardiac function. A major challenge in the field is to understand how these and other actors work together in intact myocytes to fine-tune ion channel expression and control cardiac excitability.
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Affiliation(s)
- Elise Balse
- Institute of Cardiometabolism and Nutrition, Paris, France; Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Heart and Metabolism Division, Paris, France; Institut National de la Santé et de la Recherche Médicale UMR_S956, Paris, France; Université Pierre et Marie Curie, Paris, France; Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, Canada; and Department of Clinical Research University of Bern, Bern, Switzerland
| | - David F. Steele
- Institute of Cardiometabolism and Nutrition, Paris, France; Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Heart and Metabolism Division, Paris, France; Institut National de la Santé et de la Recherche Médicale UMR_S956, Paris, France; Université Pierre et Marie Curie, Paris, France; Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, Canada; and Department of Clinical Research University of Bern, Bern, Switzerland
| | - Hugues Abriel
- Institute of Cardiometabolism and Nutrition, Paris, France; Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Heart and Metabolism Division, Paris, France; Institut National de la Santé et de la Recherche Médicale UMR_S956, Paris, France; Université Pierre et Marie Curie, Paris, France; Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, Canada; and Department of Clinical Research University of Bern, Bern, Switzerland
| | - Alain Coulombe
- Institute of Cardiometabolism and Nutrition, Paris, France; Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Heart and Metabolism Division, Paris, France; Institut National de la Santé et de la Recherche Médicale UMR_S956, Paris, France; Université Pierre et Marie Curie, Paris, France; Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, Canada; and Department of Clinical Research University of Bern, Bern, Switzerland
| | - David Fedida
- Institute of Cardiometabolism and Nutrition, Paris, France; Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Heart and Metabolism Division, Paris, France; Institut National de la Santé et de la Recherche Médicale UMR_S956, Paris, France; Université Pierre et Marie Curie, Paris, France; Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, Canada; and Department of Clinical Research University of Bern, Bern, Switzerland
| | - Stéphane N. Hatem
- Institute of Cardiometabolism and Nutrition, Paris, France; Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Heart and Metabolism Division, Paris, France; Institut National de la Santé et de la Recherche Médicale UMR_S956, Paris, France; Université Pierre et Marie Curie, Paris, France; Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, Canada; and Department of Clinical Research University of Bern, Bern, Switzerland
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Harmel N, Cokic B, Zolles G, Berkefeld H, Mauric V, Fakler B, Stein V, Klöcker N. AMPA receptors commandeer an ancient cargo exporter for use as an auxiliary subunit for signaling. PLoS One 2012; 7:e30681. [PMID: 22292017 PMCID: PMC3265512 DOI: 10.1371/journal.pone.0030681] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Accepted: 12/27/2011] [Indexed: 01/18/2023] Open
Abstract
Fast excitatory neurotransmission in the mammalian central nervous system is mainly mediated by ionotropic glutamate receptors of the AMPA subtype (AMPARs). AMPARs are protein complexes of the pore-lining α-subunits GluA1-4 and auxiliary β-subunits modulating their trafficking and gating. By a proteomic approach, two homologues of the cargo exporter cornichon, CNIH-2 and CNIH-3, have recently been identified as constituents of native AMPARs in mammalian brain. In heterologous reconstitution experiments, CNIH-2 promotes surface expression of GluAs and modulates their biophysical properties. However, its relevance in native AMPAR physiology remains controversial. Here, we have studied the role of CNIH-2 in GluA processing both in heterologous cells and primary rat neurons. Our data demonstrate that CNIH-2 serves an evolutionarily conserved role as a cargo exporter from the endoplasmic reticulum (ER). CNIH-2 cycles continuously between ER and Golgi complex to pick up cargo protein in the ER and then to mediate its preferential export in a coat protein complex (COP) II dependent manner. Interaction with GluA subunits breaks with this ancestral role of CNIH-2 confined to the early secretory pathway. While still taking advantage of being exported preferentially from the ER, GluAs recruit CNIH-2 to the cell surface. Thus, mammalian AMPARs commandeer CNIH-2 for use as a bona fide auxiliary subunit that is able to modify receptor signaling.
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Affiliation(s)
- Nadine Harmel
- Institute of Neuro- and Sensory Physiology, Medical Faculty, University of Düsseldorf, Düsseldorf, Germany
| | - Barbara Cokic
- Department of Synaptic Receptor Trafficking, Max-Planck-Institute of Neurobiology, Martinsried, Germany
| | - Gerd Zolles
- Institute of Physiology, University of Freiburg, Freiburg, Germany
| | | | - Veronika Mauric
- Institute of Neuro- and Sensory Physiology, Medical Faculty, University of Düsseldorf, Düsseldorf, Germany
| | - Bernd Fakler
- Institute of Physiology, University of Freiburg, Freiburg, Germany
- Center for Biological Signaling Studies (BIOSS), Freiburg, Germany
| | - Valentin Stein
- Department of Physiology, University of Bonn, Bonn, Germany
| | - Nikolaj Klöcker
- Institute of Neuro- and Sensory Physiology, Medical Faculty, University of Düsseldorf, Düsseldorf, Germany
- * E-mail:
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Feig SL, Haberly LB. Surface-associated astrocytes, not endfeet, form the glia limitans in posterior piriform cortex and have a spatially distributed, not a domain, organization. J Comp Neurol 2011; 519:1952-69. [PMID: 21452238 DOI: 10.1002/cne.22615] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
"Surface-associated astrocytes" (SAAs) in posterior piriform cortex (PPC) are unique by virtue of a direct apposition to the cortical surface and large-caliber processes that descend into layer I. In this study additional unique and functionally relevant features of SAAs in PPC of the rat were identified by light and electron microscopy. Examination of sections cut parallel to the surface of PPC and stained for glial fibrillar acidic protein revealed that, in addition to descending processes, SAAs give rise to an extensive matrix of "superficial processes." Electron microscopy revealed that these superficial processes, together with cell bodies, form a continuous sheet at the surface of PPC with features in common with the glia limitans that is formed by endfeet in other cortical areas. These include a glia limiting membrane with basal lamina and similar associated organelles, including a striking array of mitochondria. Of particular interest, SAAs lack the domain organization observed in neocortex and hippocampus. Rather, superficial processes overlap extensively with gap junctions between their proximal regions as well as between cell bodies. Study of the descending processes revealed thin extensions, many of which appose synaptic profiles. We conclude that SAAs provide a potential substrate for bidirectional signaling and transport between brain and the pial arteries and cerebrospinal fluid in the subarachnoid space. We postulate that the spatially distributed character of SAAs in PPC reflects and supports the spatially distributed circuitry and sensory representation that are also unique features of this area.
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Affiliation(s)
- S L Feig
- Department of Anatomy and Neuroscience Training Program, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706, USA.
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41
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Dassau L, Conti LR, Radeke CM, Ptáček LJ, Vandenberg CA. Kir2.6 regulates the surface expression of Kir2.x inward rectifier potassium channels. J Biol Chem 2011; 286:9526-41. [PMID: 21209095 DOI: 10.1074/jbc.m110.170597] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Precise trafficking, localization, and activity of inward rectifier potassium Kir2 channels are important for shaping the electrical response of skeletal muscle. However, how coordinated trafficking occurs to target sites remains unclear. Kir2 channels are tetrameric assemblies of Kir2.x subunits. By immunocytochemistry we show that endogenous Kir2.1 and Kir2.2 are localized at the plasma membrane and T-tubules in rodent skeletal muscle. Recently, a new subunit, Kir2.6, present in human skeletal muscle, was identified as a gene in which mutations confer susceptibility to thyrotoxic hypokalemic periodic paralysis. Here we characterize the trafficking and interaction of wild type Kir2.6 with other Kir2.x in COS-1 cells and skeletal muscle in vivo. Immunocytochemical and electrophysiological data demonstrate that Kir2.6 is largely retained in the endoplasmic reticulum, despite high sequence identity with Kir2.2 and conserved endoplasmic reticulum and Golgi trafficking motifs shared with Kir2.1 and Kir2.2. We identify amino acids responsible for the trafficking differences of Kir2.6. Significantly, we show that Kir2.6 subunits can coassemble with Kir2.1 and Kir2.2 in vitro and in vivo. Notably, this interaction limits the surface expression of both Kir2.1 and Kir2.2. We provide evidence that Kir2.6 functions as a dominant negative, in which incorporation of Kir2.6 as a subunit in a Kir2 channel heterotetramer reduces the abundance of Kir2 channels on the plasma membrane.
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Affiliation(s)
- Lior Dassau
- Department of Molecular, Cellular, and Developmental Biology and the Neuroscience Research Institute, University of California, Santa Barbara, California 93106, USA
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Hibino H, Inanobe A, Furutani K, Murakami S, Findlay I, Kurachi Y. Inwardly rectifying potassium channels: their structure, function, and physiological roles. Physiol Rev 2010; 90:291-366. [PMID: 20086079 DOI: 10.1152/physrev.00021.2009] [Citation(s) in RCA: 1081] [Impact Index Per Article: 77.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Inwardly rectifying K(+) (Kir) channels allow K(+) to move more easily into rather than out of the cell. They have diverse physiological functions depending on their type and their location. There are seven Kir channel subfamilies that can be classified into four functional groups: classical Kir channels (Kir2.x) are constitutively active, G protein-gated Kir channels (Kir3.x) are regulated by G protein-coupled receptors, ATP-sensitive K(+) channels (Kir6.x) are tightly linked to cellular metabolism, and K(+) transport channels (Kir1.x, Kir4.x, Kir5.x, and Kir7.x). Inward rectification results from pore block by intracellular substances such as Mg(2+) and polyamines. Kir channel activity can be modulated by ions, phospholipids, and binding proteins. The basic building block of a Kir channel is made up of two transmembrane helices with cytoplasmic NH(2) and COOH termini and an extracellular loop which folds back to form the pore-lining ion selectivity filter. In vivo, functional Kir channels are composed of four such subunits which are either homo- or heterotetramers. Gene targeting and genetic analysis have linked Kir channel dysfunction to diverse pathologies. The crystal structure of different Kir channels is opening the way to understanding the structure-function relationships of this simple but diverse ion channel family.
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Affiliation(s)
- Hiroshi Hibino
- Department of Pharmacology, Graduate School of Medicine and The Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka 565-0871, Japan
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Marcello E, Gardoni F, Di Luca M, Pérez-Otaño I. An arginine stretch limits ADAM10 exit from the endoplasmic reticulum. J Biol Chem 2010; 285:10376-84. [PMID: 20100836 DOI: 10.1074/jbc.m109.055947] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A disintegrin and metalloproteinase 10 (ADAM10) is a type I transmembrane glycoprotein responsible for the ectodomain shedding of a number of proteins implicated in the pathogenesis of diseases ranging from cancer to Alzheimer Disease. ADAM10 is synthesized in an inactive form, which is proteolytically activated during its forward transport along the secretory pathway and at the plasma membrane. Therefore, modulation of its trafficking could provide a mechanism to finely tune its shedding activity. Here we report the identification of an endoplasmic reticulum (ER) retention motif within the ADAM10 intracellular C-terminal tail. Sequential deletion/mutagenesis analyses showed that an arginine-rich ((723)RRR) sequence was responsible for the retention of ADAM10 in the ER and its inefficient surface trafficking. Mutating the second arginine to alanine was sufficient to allow ER exit and surface expression in both heterologous cells and hippocampal neurons. As synapse-associated protein 97 (SAP97) binds ADAM10 at its cytoplasmic tail and facilitates forward ADAM10 trafficking in neurons, we tested whether SAP97 could modulate ER export. However, neither expression nor Ser-39 phosphorylation of SAP97 in heterologous cells or hippocampal neurons were sufficient to allow the ER exit of ADAM10, suggesting that other signaling pathways or alternative binding partners are responsible for ADAM10 ER exit. Together, these results identify a novel mechanism regulating the intracellular trafficking and membrane delivery of ADAM10.
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Affiliation(s)
- Elena Marcello
- Department of Pharmacological Sciences and Centre of Excellence on Neurodegenerative Diseases, Università degli Studi di Milano, via Balzaretti 9, 20133 Milan, Italy.
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Nobukuni M, Mochizuki H, Okada S, Kameyama N, Tanaka A, Yamamoto H, Amano T, Seki T, Sakai N. The C-Terminal Region of Serotonin Transporter Is Important for Its Trafficking and Glycosylation. J Pharmacol Sci 2009; 111:392-404. [DOI: 10.1254/jphs.09195fp] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Sieben C, Mikosch M, Brandizzi F, Homann U. Interaction of the K(+)-channel KAT1 with the coat protein complex II coat component Sec24 depends on a di-acidic endoplasmic reticulum export motif. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 56:997-1006. [PMID: 18702673 DOI: 10.1111/j.1365-313x.2008.03658.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The correct functioning of ion channels depends not only on the control of their activity but also on the regulation of the number of channels in the membrane. For example, it has been proposed that the density of the plant K(+)-channel KAT1 may be adjusted by controlling its export from its site of synthesis, the endoplasmic reticulum (ER). Efficient transport of the channel to the plasma membrane was found to depend on a di-acidic ER export signal in the C-terminus of the protein. Studies in yeast and mammals indicate that di-acidic ER export motifs are essential for enrichment of proteins into ER-derived coat protein complex II (COPII) vesicles and are recognized by Sec24 a component of the COPII coat. To investigate whether similar mechanisms also exist in plants we have analysed the interaction of KAT1 with Sec24 in vivo using fluorescence resonance energy transfer (FRET) measurements in Vicia faba guard cells. These measurements revealed a FRET signal between KAT1 and Sec24 fused to the cyan fluorescent protein and the yellow fluorescent protein, respectively, indicating an interaction between KAT1 and Sec24. The FRET signal only occurred in the perinuclear region of the ER and was dependent on the di-acidic ER export motif of KAT1. Together, the results point to a highly conserved mechanism for ER export of KAT1 whereby the channel is recruited into COPII vesicles via binding of the di-acidic motif to Sec24.
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Affiliation(s)
- Christian Sieben
- Institute of Botany, Technical University of Darmstadt, 64287 Darmstadt, Germany
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Soroka CJ, Xu S, Mennone A, Lam P, Boyer JL. N-Glycosylation of the alpha subunit does not influence trafficking or functional activity of the human organic solute transporter alpha/beta. BMC Cell Biol 2008; 9:57. [PMID: 18847488 PMCID: PMC2575201 DOI: 10.1186/1471-2121-9-57] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Accepted: 10/10/2008] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The organic solute transporter (OSTalpha-OSTbeta) is a heteromeric transporter that is expressed on the basolateral membrane of epithelium in intestine, kidney, liver, testis and adrenal gland and facilitates efflux of bile acids and other steroid solutes. Both subunits are required for plasma membrane localization of the functional transporter but it is unclear how and where the subunits interact and whether glycosylation is required for functional activity. We sought to examine these questions for the human OSTalpha-OSTbeta transporter using the human hepatoma cell line, HepG2, and COS7 cells transfected with constructs of human OSTalpha-FLAG and OSTbeta-Myc. RESULTS Tunicamycin treatment demonstrated that human OSTalpha is glycosylated. In COS7 cells Western blotting identified the unglycosylated form (approximately 31 kD), the core precursor form (approximately 35 kD), and the mature, complex glycoprotein (approximately 40 kD). Immunofluorescence of both cells indicated that, in the presence of OSTbeta, the alpha subunit could still be expressed on the plasma membrane after tunicamycin treatment. Furthermore, the functional uptake of 3H-estrone sulfate was unchanged in the absence of N-glycosylation. Co-immunoprecipitation indicates that the immature form of OSTalpha interact with OSTbeta. However, immunoprecipitation of OSTbeta using an anti-Myc antibody did not co-precipitate the mature, complex glycosylated form of OSTalpha, suggesting that the primary interaction occurs early in the biosynthetic pathway and may be transient. CONCLUSION In conclusion, human OSTalpha is a glycoprotein that requires interaction with OSTbeta to reach the plasma membrane. However, glycosylation of OSTalpha is not necessary for interaction with the beta subunit or for membrane localization or function of the heteromeric transporter.
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Affiliation(s)
- Carol J Soroka
- Department of Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Shuhua Xu
- Department of Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Albert Mennone
- Department of Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Ping Lam
- Department of Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - James L Boyer
- Department of Medicine, Yale University School of Medicine, New Haven, CT, USA
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Gradinaru V, Thompson KR, Deisseroth K. eNpHR: a Natronomonas halorhodopsin enhanced for optogenetic applications. ACTA ACUST UNITED AC 2008; 36:129-39. [PMID: 18677566 DOI: 10.1007/s11068-008-9027-6] [Citation(s) in RCA: 362] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Revised: 06/13/2008] [Accepted: 06/17/2008] [Indexed: 11/29/2022]
Abstract
Temporally precise inhibition of distinct cell types in the intact nervous system has been enabled by the microbial halorhodopsin NpHR, a fast light-activated electrogenic Cl(-) pump. While neurons can be optically hyperpolarized and inhibited from firing action potentials at moderate NpHR expression levels, we have encountered challenges with pushing expression to extremely high levels, including apparent intracellular accumulations. We therefore sought to molecularly engineer NpHR to achieve strong expression without these cellular side effects. We found that high expression correlated with endoplasmic reticulum (ER) accumulation, and that under these conditions NpHR colocalized with ER proteins containing the KDEL ER retention sequence. We screened a number of different putative modulators of membrane trafficking and identified a combination of two motifs, an N-terminal signal peptide and a C-terminal ER export sequence, that markedly promoted membrane localization and ER export defined by confocal microscopy and whole-cell patch clamp. The modified NpHR displayed increased peak photocurrent in the absence of aggregations or toxicity, and potent optical inhibition was observed not only in vitro but also in vivo with thalamic single-unit recording. The new enhanced NpHR (eNpHR) allows safe, high-level expression in mammalian neurons, without toxicity and with augmented inhibitory function, in vitro and in vivo.
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Affiliation(s)
- Viviana Gradinaru
- Department of Bioengineering, Stanford University, W083 Clark Center, 318 Campus Drive West, Stanford, CA, USA
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Mckeown L, Burnham MP, Hodson C, Jones OT. Identification of an evolutionarily conserved extracellular threonine residue critical for surface expression and its potential coupling of adjacent voltage-sensing and gating domains in voltage-gated potassium channels. J Biol Chem 2008; 283:30421-32. [PMID: 18640987 DOI: 10.1074/jbc.m708921200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The dynamic expression of voltage-gated potassium channels (Kvs) at the cell surface is a fundamental factor controlling membrane excitability. In exploring possible mechanisms controlling Kv surface expression, we identified a region in the extracellular linker between the first and second of the six (S1-S6) transmembrane-spanning domains of the Kv1.4 channel, which we hypothesized to be critical for its biogenesis. Using immunofluorescence microscopy, flow cytometry, patch clamp electrophysiology, and mutagenesis, we identified a single threonine residue at position 330 within the Kv1.4 S1-S2 linker that is absolutely required for cell surface expression. Mutation of Thr-330 to an alanine, aspartate, or lysine prevented surface expression. However, surface expression occurred upon co-expression of mutant and wild type Kv1.4 subunits or mutation of Thr-330 to a serine. Mutation of the corresponding residue (Thr-211) in Kv3.1 to alanine also caused intracellular retention, suggesting that the conserved threonine plays a generalized role in surface expression. In support of this idea, sequence comparisons showed conservation of the critical threonine in all Kv families and in organisms across the evolutionary spectrum. Based upon the Kv1.2 crystal structure, further mutagenesis, and the partial restoration of surface expression in an electrostatic T330K bridging mutant, we suggest that Thr-330 hydrogen bonds to equally conserved outer pore residues, which may include a glutamate at position 502 that is also critical for surface expression. We propose that Thr-330 serves to interlock the voltage-sensing and gating domains of adjacent monomers, thereby yielding a structure competent for the surface expression of functional tetramers.
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Affiliation(s)
- Lynn Mckeown
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PN, United Kingdom
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KUCHERYAVYKH YURIYV, SHUBA YAROSLAVM, ANTONOV SERGEIM, INYUSHIN MIKHAILY, CUBANO LUIS, PEARSON WADEL, KURATA HARLEY, REICHENBACH ANDREAS, VEH RÜDIGERW, NICHOLS COLING, EATON MISTYJ, SKATCHKOV SERGUEIN. Complex rectification of Müller cell Kir currents. Glia 2008; 56:775-90. [PMID: 18293411 PMCID: PMC9930535 DOI: 10.1002/glia.20652] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Although Kir4.1 channels are the major inwardly rectifying channels in glial cells and are widely accepted to support K+- and glutamate-uptake in the nervous system, the properties of Kir4.1 channels during vital changes of K+ and polyamines remain poorly understood. Therefore, the present study examined the voltage-dependence of K+ conductance with varying physiological and pathophysiological external [K+] and intrapipette spermine ([SP]) concentrations in Müller glial cells and in tsA201 cells expressing recombinant Kir4.1 channels. Two different types of [SP] block were characterized: "fast" and "slow." Fast block was steeply voltage-dependent, with only a low sensitivity to spermine and strong dependence on extracellular potassium concentration, [K+]o. Slow block had a strong voltage sensitivity that begins closer to resting membrane potential and was essentially [K+]o-independent, but with a higher spermine- and [K+]i-sensitivity. Using a modified Woodhull model and fitting i/V curves from whole cell recordings, we have calculated free [SP](in) in Müller glial cells as 0.81 +/- 0.24 mM. This is much higher than has been estimated previously in neurons. Biphasic block properties underlie a significantly varying extent of rectification with [K+] and [SP]. While confirming similar properties of glial Kir and recombinant Kir4.1, the results also suggest mechanisms underlying K+ buffering in glial cells: When [K+]o is rapidly increased, as would occur during neuronal excitation, "fast block" would be relieved, promoting potassium influx to glial cells. Increase in [K+]in would then lead to relief of "slow block," further promoting K+-influx.
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Affiliation(s)
- YURIY V. KUCHERYAVYKH
- Department of Biochemistry, Universidad Central del Caribe, School of Medicine, Bayamón, PR
| | - YAROSLAV M. SHUBA
- International Center of Molecular Physiology, National Academy of Sciences of Ukraine, Kiev, 01024 Ukraine
| | - SERGEI M. ANTONOV
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, 194223 Russia
| | - MIKHAIL Y. INYUSHIN
- Department of Physiology, Universidad Central del Caribe, School of Medicine, Bayamón, PR
| | - LUIS CUBANO
- Department of Anatomy and Cell Biology, Universidad Central del Caribe, School of Medicine, Bayamón, PR
| | - WADE L. PEARSON
- Department of Cell Biology and Physiology, Washington University, School of Medicine, St. Louis, MO
| | - HARLEY KURATA
- Department of Cell Biology and Physiology, Washington University, School of Medicine, St. Louis, MO
| | - ANDREAS REICHENBACH
- Paul Flechsig Institute of Brain Research, Leipzig University, D-04109 Leipzig, Germany
| | - RÜDIGER W. VEH
- Institute of Integrative Neuroanatomy, Charité, Philipstrasse 12, Berlin, Germany
| | - COLIN G. NICHOLS
- Department of Cell Biology and Physiology, Washington University, School of Medicine, St. Louis, MO
| | - MISTY J. EATON
- Department of Biochemistry, Universidad Central del Caribe, School of Medicine, Bayamón, PR
| | - SERGUEI N. SKATCHKOV
- Department of Biochemistry, Universidad Central del Caribe, School of Medicine, Bayamón, PR,Department of Physiology, Universidad Central del Caribe, School of Medicine, Bayamón, PR,Correspondence to: S. N. Skatchkov, Departments of Biochemistry and Physiology, School of Medicine, Universidad Central del Caribe, Box 60-327, Bayamón, Puerto Rico, USA 00960-6032.
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Beerens AMJ, Rots MG, Bermúdez B, de Vries EFJ, Haisma HJ. Secretion of thymidine kinase to increase the effectivity of suicide gene therapy results in the loss of enzymatic activity. J Drug Target 2008; 16:26-35. [PMID: 18172817 DOI: 10.1080/10611860701637768] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Low efficiency of gene transfer is one of the major limitations of gene therapy. A solution to this problem may be transmission; by modification of the transgene, the gene product can be secreted and internalized by the surrounding cells. Cancer gene therapy using the herpes simplex thymidine kinase (HSV-TK) suicide gene is a promising treatment, and TK has been used in clinical trials with some success. However, this kind of therapy has limited efficacy due to the low level of gene transfer reached. A modified TK protein, capable of migrating from the producing cell to neighboring cells, would result in a greater proportion of cells affected by the treatment. As a first step towards transmission, we constructed a secretory form of HSV-TK by including the Igkappa leader peptide in the gene. An endoplasmatic reticulum export signal was added to the construct to further improve its secretion. Secretion and protein production in cancer cells, the enzymatic activity of the modified proteins and the ability of the modified TK to sensitize cancer cells to ganciclovir were tested. Addition of the Igkappa leader resulted in high levels of secretion of HSV-TK, with up to 70% of the total amount of protein secreted. Inclusion of an ER export signal did not further improve secretion. The enzyme activity of the secreted TK however, was decreased when compared to native TK. This study is the first to report on secretion of TK, and provides a first step in a novel strategy to improve the efficiency of cancer gene therapy. The loss of function in secreted TK however, may present a major hurdle in the development of a transmitted form of TK.
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Affiliation(s)
- A M J Beerens
- Department of Therapeutic Gene Modulation, University Centre for Pharmacy, University of Groningen, Groningen, The Netherlands
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