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Ma L, Kasula RK, Ouyang Q, Schmidt M, Morrow EM. GGA1 interacts with the endosomal Na+/H+ exchanger NHE6 governing localization to the endosome compartment. J Biol Chem 2024; 300:107552. [PMID: 39002678 DOI: 10.1016/j.jbc.2024.107552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 06/20/2024] [Accepted: 06/27/2024] [Indexed: 07/15/2024] Open
Abstract
Mutations in the endosomal Na+/H+ exchanger 6 (NHE6) cause Christianson syndrome, an X-linked neurological disorder. NHE6 functions in regulation of endosome acidification and maturation in neurons. Using yeast two-hybrid screening with the NHE6 carboxyl terminus as bait, we identify Golgi-associated, gamma adaptin ear-containing, ADP-ribosylation factor (ARF) binding protein 1 (GGA1) as an interacting partner for NHE6. We corroborated the NHE6-GGA1 interaction using: coimmunoprecipitation; overexpressed constructs in mammalian cells; and coimmunoprecipitation of endogenously expressed GGA1 and NHE6 from neuroblastoma cells, as well as from the mouse brain. We demonstrate that GGA1 interacts with organellar NHEs (NHE6, NHE7, and NHE9) and that there is significantly less interaction with cell-surface localized NHEs (NHE1 and NHE5). By constructing hybrid NHE1/NHE6 exchangers, we demonstrate the cytoplasmic tail of NHE6 interacts most strongly with GGA1. We demonstrate the colocalization of NHE6 and GGA1 in cultured, primary hippocampal neurons, using super-resolution microscopy. We test the hypothesis that the interaction of NHE6 and GGA1 functions in the localization of NHE6 to the endosome compartment. Using subcellular fractionation experiments, we show that NHE6 is mislocalized in GGA1 KO cells, wherein we find less NHE6 in endosomes, but more NHE6 transport to lysosomes, and more Golgi retention of NHE6, with increased exocytosis to the surface plasma membrane. Consistent with NHE6 mislocalization, and Golgi retention, we find the intraluminal pH in Golgi to be alkalinized in GGA1-null cells. Our study demonstrates a new interaction between NHE6 and GGA1 which functions in the localization of this intracellular NHE to the endosome compartment.
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Affiliation(s)
- Li Ma
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA; Center for Translational Neuroscience, Brown University, Providence, Rhode Island, USA
| | - Ravi Kiran Kasula
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA; Center for Translational Neuroscience, Brown University, Providence, Rhode Island, USA
| | - Qing Ouyang
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA; Center for Translational Neuroscience, Brown University, Providence, Rhode Island, USA
| | - Michael Schmidt
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA; Center for Translational Neuroscience, Brown University, Providence, Rhode Island, USA
| | - Eric M Morrow
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA; Center for Translational Neuroscience, Brown University, Providence, Rhode Island, USA.
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Ma L, Kasula RK, Ouyang Q, Schmidt M, Morrow EM. GGA1 interacts with the endosomal Na+/H+ Exchanger NHE6 governing localization to the endosome compartment. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.08.565997. [PMID: 37986849 PMCID: PMC10659387 DOI: 10.1101/2023.11.08.565997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Mutations in the endosomal Na+/H+ exchanger (NHE6) cause Christianson syndrome (CS), an X-linked neurological disorder. Previous studies have shown that NHE6 functions in regulation of endosome acidification and maturation in neurons. Using yeast two-hybrid screening with the NHE6 carboxyl-terminus as bait, we identify Golgi-associated, Gamma adaptin ear containing, ARF binding protein 1 (GGA1) as an interacting partner for NHE6. We corroborated the NHE6-GGA1 interaction using co-immunoprecipitation (co-IP): using over-expressed constructs in mammalian cells; and co-IP of endogenously-expressed GGA1 and NHE6 from neuroblastoma cells, as well as from mouse brain. We demonstrate that GGA1 interacts with organellar NHEs (NHE6, NHE7 and NHE9) but not with cell-surface localized NHEs (NHE1 and NHE5). By constructing hybrid NHE1/NHE6 exchangers, we demonstrate that the cytoplasmic tail of NHE6 is necessary and sufficient for interactions with GGA1. We demonstrate the co-localization of NHE6 and GGA1 in cultured, primary hippocampal neurons, using super-resolution microscopy. We test the hypothesis that the interaction of NHE6 and GGA1 functions in the localization of NHE6 to the endosome compartment. Using subcellular fractionation experiments, we show that NHE6 is mis-localized in GGA1 knockout cells wherein we find less NHE6 in endosomes but more NHE6 transport to lysosomes, and more Golgi retention of NHE6 with increased exocytosis to the surface plasma membrane. Consistent with NHE6 mis-localization, and Golgi retention, we find the intra-luminal pH in Golgi to be alkalinized. Our study demonstrates a new interaction between NHE6 and GGA1 which functions in the localization of this intra-cellular NHE to the endosome compartment.
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Chen Y, Fan J, Xiao D, Li X. The role of SCAMP5 in central nervous system diseases. Neurol Res 2022; 44:1024-1037. [PMID: 36217917 DOI: 10.1080/01616412.2022.2107754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
OBJECTIVE Secretory carrier membrane proteins (SCAMPs) constitute a group of membrane transport proteins in plants, insects and mammals. The mammalian genome contains five types of SCAMP genes, namely, SCAMP1-SCAMP5. SCAMPs participate in the vesicle cycling fusion of vesicles and cell membranes and play roles in regulating exocytosis and endocytosis, activating synaptic function and transmitting nerve signals. Among these proteins, SCAMP5 is highly expressed in the brain and has direct or indirect effects on the function of the central nervous system. This paper may allow us to better understand the role of SCAMP5 in the central nervous system diseases. SCAMP5 regulates membrane transport, controls the exocytosis of SVs and is related to secretion carrier and membrane function. In addition, SCAMP5 plays a major role in the normal maintenance of the physiological functions of nerve cells. This article summarizes the effects of SCAMP5 on nerve cell exocytosis, endocytosis and synaptic function, as well as the relationship between SCAMP5 and various neurological diseases, to better understand the role of SCAMP5 in the pathogenesis of neurological diseases. METHODS Through PubMed, this paper examined and analyzed the role of SCAMP5 in the central nervous system, as well as the relationship between SCAMP5 and various neurological diseases using the key terms "secretory carrier membrane proteins"," SCAMP5"," exocytosis"," endocytosis", "synaptic function", "central nervous system diseases" up to 01 March 2022. RESULTS SCAMP5 regulates membrane transport, controls the exocytosis of SVs and is related to secretion carrier and membrane function. In addition, SCAMP5 plays a major role in the normal maintenance of the physiological functions of nerve cells. CONCLUSION This article summarizes the effects of SCAMP5 on nerve cell exocytosis, endocytosis and synaptic function, as well as the relationship between SCAMP5 and various neurological diseases, to better understand the role of SCAMP5 in the pathogenesis of neurological diseases.
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Affiliation(s)
- Ye Chen
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China.,Ministry of Education, Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Chengdu, Sichuan, China
| | - Jiali Fan
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China.,Ministry of Education, Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Chengdu, Sichuan, China
| | - Dongqiong Xiao
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China.,Ministry of Education, Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Chengdu, Sichuan, China
| | - Xihong Li
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China.,Ministry of Education, Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Chengdu, Sichuan, China
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Chen C, Wen M, Jin Y. 1DE-MS Profiling for Proteoform-Correlated Proteomic Analysis, by Combining SDS-PAGE, Whole-Gel Slicing, Quantitative LC-MS/MS, and Reconstruction of Gel Distributions of Several Thousands of Proteins. J Proteome Res 2022; 21:2311-2330. [PMID: 36018058 DOI: 10.1021/acs.jproteome.2c00180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
SDS-PAGE has often been used in proteomic analysis, but generally for sample prefractionation although the technique separates proteins by molecular masses (Mws) and the information would contribute to proteoform-level analysis. Here, we report a method that combines SDS-PAGE, whole-gel slicing, and quantitative LC-MS/MS for establishing gel distributions of several thousand proteins in a proteome. A previously obtained data set on rat cerebral cortex with cerebral ischemia-reperfusion injury1 was analyzed, and the gel distributions of 5906 proteins were reconstructed. These distributions, referred to as 1DE-MS profiles, revealed that about 30% of the proteins had more than one proteoform detected in the gels. The profiles were categorized into six types by distribution (narrow, dispersed, or broad) and relative deviations between the abundance-peak apparent Mws and calculated Mws. Only 56% of the proteins showed narrow distributions and matched Mws, while the others had rather complex profiles. Bioinformatic analysis on example profiles showed the resolved proteoforms involved alternative splicing, proteolytic processing, glycosylation and ubiquitination, fragmentation, and probably transmembrane structures. Profile-based differential analysis revealed that many of the disease-caused changes were proteoform dependent. This work provided a proteome-scale view of protein distributions in SDS-PAGE gels, and the method would be useful to obtain proteoform-correlated information for in-depth proteomics.
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Affiliation(s)
- Changming Chen
- Institute of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou 510006, P. R. China
| | - Meiling Wen
- Institute of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou 510006, P. R. China
| | - Ya Jin
- Institute of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou 510006, P. R. China
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Hori T, Takamori S. Physiological Perspectives on Molecular Mechanisms and Regulation of Vesicular Glutamate Transport: Lessons From Calyx of Held Synapses. Front Cell Neurosci 2022; 15:811892. [PMID: 35095427 PMCID: PMC8793065 DOI: 10.3389/fncel.2021.811892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 12/07/2021] [Indexed: 12/02/2022] Open
Abstract
Accumulation of glutamate, the primary excitatory neurotransmitter in the mammalian central nervous system, into presynaptic synaptic vesicles (SVs) depends upon three vesicular glutamate transporters (VGLUTs). Since VGLUTs are driven by a proton electrochemical gradient across the SV membrane generated by vacuolar-type H+-ATPases (V-ATPases), the rate of glutamate transport into SVs, as well as the amount of glutamate in SVs at equilibrium, are influenced by activities of both VGLUTs and V-ATPase. Despite emerging evidence that suggests various factors influencing glutamate transport by VGLUTs in vitro, little has been reported in physiological or pathological contexts to date. Historically, this was partially due to a lack of appropriate methods to monitor glutamate loading into SVs in living synapses. Furthermore, whether or not glutamate refilling of SVs can be rate-limiting for synaptic transmission is not well understood, primarily due to a lack of knowledge concerning the time required for vesicle reuse and refilling during repetitive stimulation. In this review, we first introduce a unique electrophysiological method to monitor glutamate refilling by VGLUTs in a giant model synapse from the calyx of Held in rodent brainstem slices, and we discuss the advantages and limitations of the method. We then introduce the current understanding of factors that potentially alter the amount and rate of glutamate refilling of SVs in this synapse, and discuss open questions from physiological viewpoints.
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Affiliation(s)
- Tetsuya Hori
- Cellular and Molecular Synaptic Function Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
- *Correspondence: Tetsuya Hori Shigeo Takamori
| | - Shigeo Takamori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto, Japan
- *Correspondence: Tetsuya Hori Shigeo Takamori
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Pohlkamp T, Xian X, Wong CH, Durakoglugil MS, Werthmann GC, Saido TC, Evers BM, White CL, Connor J, Hammer RE, Herz J. NHE6 depletion corrects ApoE4-mediated synaptic impairments and reduces amyloid plaque load. eLife 2021; 10:72034. [PMID: 34617884 PMCID: PMC8547963 DOI: 10.7554/elife.72034] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 09/19/2021] [Indexed: 11/13/2022] Open
Abstract
Apolipoprotein E4 (ApoE4) is the most important and prevalent risk factor for late-onset Alzheimer’s disease (AD). The isoelectric point of ApoE4 matches the pH of the early endosome (EE), causing its delayed dissociation from ApoE receptors and hence impaired endolysosomal trafficking, disruption of synaptic homeostasis, and reduced amyloid clearance. We have shown that enhancing endosomal acidification by inhibiting the EE-specific sodium-hydrogen exchanger 6 (NHE6) restores vesicular trafficking and normalizes synaptic homeostasis. Remarkably and unexpectedly, loss of NHE6 (encoded by the gene Slc9a6) in mice effectively suppressed amyloid deposition even in the absence of ApoE4, suggesting that accelerated acidification of EEs caused by the absence of NHE6 occludes the effect of ApoE on amyloid plaque formation. NHE6 suppression or inhibition may thus be a universal, ApoE-independent approach to prevent amyloid buildup in the brain. These findings suggest a novel therapeutic approach for the prevention of AD by which partial NHE6 inhibition reverses the ApoE4-induced endolysosomal trafficking defect and reduces plaque load.
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Affiliation(s)
- Theresa Pohlkamp
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States.,Center for Translational Neurodegeneration Research, Dallas, United States
| | - Xunde Xian
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States.,Center for Translational Neurodegeneration Research, Dallas, United States.,Institute of Cardiovascular Sciences and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Peking University, Beijing, China
| | - Connie H Wong
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States.,Center for Translational Neurodegeneration Research, Dallas, United States
| | - Murat S Durakoglugil
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States.,Center for Translational Neurodegeneration Research, Dallas, United States
| | - Gordon Chandler Werthmann
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States.,Center for Translational Neurodegeneration Research, Dallas, United States
| | - Takaomi C Saido
- Laboratory for Proteolytic Neuroscience, Riken Center for Brain Science, Wako, Japan
| | - Bret M Evers
- Center for Translational Neurodegeneration Research, Dallas, United States
| | - Charles L White
- Pathology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Jade Connor
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States.,Center for Translational Neurodegeneration Research, Dallas, United States
| | - Robert E Hammer
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States
| | - Joachim Herz
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States.,Center for Translational Neurodegeneration Research, Dallas, United States.,Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, United States
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