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Calabrese B, Halpain S. MARCKS and PI(4,5)P 2 reciprocally regulate actin-based dendritic spine morphology. Mol Biol Cell 2024; 35:ar23. [PMID: 38088877 PMCID: PMC10881156 DOI: 10.1091/mbc.e23-09-0370] [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: 09/19/2023] [Revised: 11/27/2023] [Accepted: 12/07/2023] [Indexed: 01/14/2024] Open
Abstract
Myristoylated, alanine-rich C-kinase substrate (MARCKS) is an F-actin and phospholipid binding protein implicated in numerous cellular activities, including the regulation of morphology in neuronal dendrites and dendritic spines. MARCKS contains a lysine-rich effector domain that mediates its binding to plasma membrane phosphatidylinositol-4,5-biphosphate (PI(4,5)P2) in a manner controlled by PKC and calcium/calmodulin. In neurons, manipulations of MARCKS concentration and membrane targeting strongly affect the numbers, shapes, and F-actin properties of dendritic spines, but the mechanisms remain unclear. Here, we tested the hypothesis that the effects of MARCKS on dendritic spine morphology are due to its capacity to regulate the availability of plasma membrane PI(4,5)P2. We observed that the concentration of free PI(4,5)P2 on the dendritic plasma membrane was inversely proportional to the concentration of MARCKS. Endogenous PI(4,5)P2 levels were increased or decreased, respectively, by acutely overexpressing either phosphatidylinositol-4-phosphate 5-kinase (PIP5K) or inositol polyphosphate 5-phosphatase (5ptase). PIP5K, like MARCKS depletion, induced severe spine shrinkage; 5ptase, like constitutively membrane-bound MARCKS, induced aberrant spine elongation. These phenotypes involved changes in actin properties driven by the F-actin severing protein cofilin. Collectively, these findings support a model in which neuronal activity regulates actin-dependent spine morphology through antagonistic interactions of MARCKS and PI(4,5)P2.
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Affiliation(s)
- Barbara Calabrese
- Department of Neurobiology, School of Biological Sciences, University of California San Diego and Sanford Consortium for Regenerative Medicine, La Jolla, CA 92037
| | - Shelley Halpain
- Department of Neurobiology, School of Biological Sciences, University of California San Diego and Sanford Consortium for Regenerative Medicine, La Jolla, CA 92037
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2
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Pan X, Pérez-Henríquez P, Van Norman JM, Yang Z. Membrane nanodomains: Dynamic nanobuilding blocks of polarized cell growth. PLANT PHYSIOLOGY 2023; 193:83-97. [PMID: 37194569 DOI: 10.1093/plphys/kiad288] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 05/03/2023] [Accepted: 05/03/2023] [Indexed: 05/18/2023]
Abstract
Cell polarity is intimately linked to numerous biological processes, such as oriented plant cell division, particular asymmetric division, cell differentiation, cell and tissue morphogenesis, and transport of hormones and nutrients. Cell polarity is typically initiated by a polarizing cue that regulates the spatiotemporal dynamic of polarity molecules, leading to the establishment and maintenance of polar domains at the plasma membrane. Despite considerable progress in identifying key polarity regulators in plants, the molecular and cellular mechanisms underlying cell polarity formation have yet to be fully elucidated. Recent work suggests a critical role for membrane protein/lipid nanodomains in polarized morphogenesis in plants. One outstanding question is how the spatiotemporal dynamics of signaling nanodomains are controlled to achieve robust cell polarization. In this review, we first summarize the current state of knowledge on potential regulatory mechanisms of nanodomain dynamics, with a special focus on Rho-like GTPases from plants. We then discuss the pavement cell system as an example of how cells may integrate multiple signals and nanodomain-involved feedback mechanisms to achieve robust polarity. A mechanistic understanding of nanodomains' roles in plant cell polarity is still in the early stages and will remain an exciting area for future investigations.
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Affiliation(s)
- Xue Pan
- Department of Biological Sciences, University of Toronto-Scarborough, Toronto, ON M1C 1A4, Canada
| | - Patricio Pérez-Henríquez
- Center for Plant Cell Biology, Institute of Integrative Genome Biology and Department of Botany and Plant Sciences, University of California at Riverside, Riverside, CA 92521, USA
| | - Jaimie M Van Norman
- Center for Plant Cell Biology, Institute of Integrative Genome Biology and Department of Botany and Plant Sciences, University of California at Riverside, Riverside, CA 92521, USA
| | - Zhenbiao Yang
- Center for Plant Cell Biology, Institute of Integrative Genome Biology and Department of Botany and Plant Sciences, University of California at Riverside, Riverside, CA 92521, USA
- Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong Province 518055, China
- FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian Province 350002, China
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3
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Wang W, Wang Z, Cao J, Dong Y, Chen Y. Roles of Rac1-Dependent Intrinsic Forgetting in Memory-Related Brain Disorders: Demon or Angel. Int J Mol Sci 2023; 24:10736. [PMID: 37445914 DOI: 10.3390/ijms241310736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 06/14/2023] [Accepted: 06/21/2023] [Indexed: 07/15/2023] Open
Abstract
Animals are required to handle daily massive amounts of information in an ever-changing environment, and the resulting memories and experiences determine their survival and development, which is critical for adaptive evolution. However, intrinsic forgetting, which actively deletes irrelevant information, is equally important for memory acquisition and consolidation. Recently, it has been shown that Rac1 activity plays a key role in intrinsic forgetting, maintaining the balance of the brain's memory management system in a controlled manner. In addition, dysfunctions of Rac1-dependent intrinsic forgetting may contribute to memory deficits in neurological and neurodegenerative diseases. Here, these new findings will provide insights into the neurobiology of memory and forgetting, pathological mechanisms and potential therapies for brain disorders that alter intrinsic forgetting mechanisms.
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Affiliation(s)
- Wei Wang
- Neurobiology Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Zixu Wang
- Neurobiology Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Jing Cao
- Neurobiology Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Yulan Dong
- Neurobiology Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Yaoxing Chen
- Neurobiology Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
- Key Laboratory of Precision Nutrition and Food Quality, Key Laboratory of Functional Dairy, Ministry of Education, Beijing Laboratory of Food Quality and Safety, Department of Nutrition and Health, China Agricultural University, Beijing 100083, China
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4
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Zhou H, Li S, Lin Y. Prognostic significance of SH2D5 expression in lung adenocarcinoma and its relation to immune cell infiltration. PeerJ 2023; 11:e15238. [PMID: 37187527 PMCID: PMC10178299 DOI: 10.7717/peerj.15238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 03/28/2023] [Indexed: 05/17/2023] Open
Abstract
Objective Through analyzing the SH2D5 expression profiles, clinical features, and immune infiltration in lung adenocarcinoma (LUAD), the study was intended to discuss the correlations of SH2D5 with prognosis and immune infiltration in LUAD. Methods We downloaded transcriptome and clinical data of LUAD patients from TCGA, GEO, and CCLE databases. Sangerbox, R language, GEPIA, UALCAN, and Kaplan-Meier Plotter were adopted to analyze the SH2D5 expression patterns, prognosis, and clinical features. Spearman correlation analysis was performed to determine the association between SH2D5 expression and immune cell infiltration and immune checkpoint genes. The miRNA-SH2D5 relations were predicted by miRDB and starbase. Lastly, quantitative PCR, IHC and Western blot were implemented for validation. Results A prominent up-regulation of SH2D5 was noted in the LUAD group relative to the normal group, which was validated by quantitative PCR, IHC and Western blot. SH2D5 expression was inversely related to overall survival (OS) of LUAD patients as well as B cell immune infiltration. Additionally, SH2D5 expression was negatively correlated with dendritic cells resting (p < 0.001), plasma cells (p < 0.001), mast cells resting (p = 0.031) and T cells CD4 memory resting (p = 0.036) in LUAD patients with abundant SH2D5 expression correlated with poor prognosis. Furthermore, enrichment analysis suggested that SH2D5 was associated with lung cancer and immunity. Lastly, we investigated the relationship between the expression of SH2D5 and the use of antitumor drugs. Conclusion High SH2D5 expression shares an association with unfavorable prognosis in LUAD, and SH2D5 may also provide new ideas for immunotherapy as a potential therapeutic target.
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Affiliation(s)
- Hao Zhou
- Department of Emergency and Critical Care Medicine, Suzhou Hospital, Affiliated Hospital of Medical School, Nanjing University, Suzhou, Jiangsu, China
| | - Shengjun Li
- Department of Emergency and Critical Care Medicine, Suzhou Hospital, Affiliated Hospital of Medical School, Nanjing University, Suzhou, Jiangsu, China
| | - Yuansheng Lin
- Department of Emergency and Critical Care Medicine, Suzhou Hospital, Affiliated Hospital of Medical School, Nanjing University, Suzhou, Jiangsu, China
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Xu X, He B, Zeng J, Yin J, Wang X, Luo X, Liang C, Luo S, Yan H, Xiong S, Tan Z, Lv D, Dai Z, Lin Z, Lin J, Ye X, Chen R, Li Y, Wang Y, Chen W, Luo Z, Li K, Ma G. Genetic variations in DOCK4 contribute to schizophrenia susceptibility in a Chinese cohort: A genetic neuroimaging study. Behav Brain Res 2023; 443:114353. [PMID: 36822513 DOI: 10.1016/j.bbr.2023.114353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Revised: 02/13/2023] [Accepted: 02/15/2023] [Indexed: 02/23/2023]
Abstract
BACKGROUND Emerging evidence suggests that the DOCK4 gene increases susceptibility to schizophrenia. However, no study has hitherto repeated this association in Chinese, and further investigated the relationship between DOCK4 and clinical symptoms in schizophrenic patients using clinical scales and functional magnetic resonance imaging (fMRI). METHODS In this study, we genotyped three single nucleotide polymorphisms (SNPs) (rs2074127, rs2217262, and rs2074130) within the DOCK4 gene using a case-control design (including 1289 healthy controls and 1351 patients with schizophrenia). 55 first-episode schizophrenia (FES) patients and 59 healthy participants were divided by the genotypes of rs2074130 into CC and CT+TT groups. We further investigated the association with clinical symptoms and neural characteristics (brain activation/connectivity and nodal network metrics). RESULTS Our results showed significant associations between all selected SNPs and schizophrenia (all P < 0.05). In patients, letter fluency and motor speed scores of T allele carriers were significantly higher than the CC group (all P < 0.05). Interestingly, greater brain activity, functional connectivity, and betweenness centrality (BC) in language processing and motor coordination were also observed in the corresponding brain zones in patients with the T allele based on a two-way ANCOVA model. Moreover, a potential positive correlation was found between brain activity/connectivity of these brain regions and verbal fluency and motor speed. CONCLUSION Our findings suggest that the DOCK4 gene may contribute to the onset of schizophrenia and lead to language processing and motor coordination dysfunction in this patient population from China.
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Affiliation(s)
- Xusan Xu
- Institute of Neurology, Guangdong Medical University, Zhanjiang 524001, China; Maternal and Children's Health Research Institute, Shunde Maternal and Children's Hospital, Guangdong Medical University, Shunde 528300, China
| | - Bin He
- Department of Radiology, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Jieqing Zeng
- Institute of Neurology, Guangdong Medical University, Zhanjiang 524001, China; Maternal and Children's Health Research Institute, Shunde Maternal and Children's Hospital, Guangdong Medical University, Shunde 528300, China
| | - Jingwen Yin
- Department of Psychiatry, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Xiaoxia Wang
- Institute of Neurology, Guangdong Medical University, Zhanjiang 524001, China; Institute of Neurology, Longjiang Hospital, the Third Affiliated Hospital of Guangdong Medical University, Shunde 528300, China
| | - Xudong Luo
- Department of Psychiatry, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Chunmei Liang
- Institute of Neurology, Guangdong Medical University, Zhanjiang 524001, China
| | - Shucun Luo
- Department of Radiology, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Haifeng Yan
- Department of Psychiatry, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Susu Xiong
- Department of Psychiatry, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Zhi Tan
- Department of Radiology, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Dong Lv
- Department of Psychiatry, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Zhun Dai
- Department of Psychiatry, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Zhixiong Lin
- Department of Psychiatry, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Juda Lin
- Department of Psychiatry, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Xiaoqing Ye
- Department of Psychiatry, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Riling Chen
- Maternal and Children's Health Research Institute, Shunde Maternal and Children's Hospital, Guangdong Medical University, Shunde 528300, China
| | - You Li
- Institute of Neurology, Guangdong Medical University, Zhanjiang 524001, China
| | - Yajun Wang
- Maternal and Children's Health Research Institute, Shunde Maternal and Children's Hospital, Guangdong Medical University, Shunde 528300, China
| | - Wubiao Chen
- Department of Radiology, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Zebin Luo
- Department of Radiology, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China.
| | - Keshen Li
- Clinical Neuroscience Institute, The First Affiliated Hospital, Jinan University, Guangzhou 510623, China.
| | - Guoda Ma
- Institute of Neurology, Guangdong Medical University, Zhanjiang 524001, China; Maternal and Children's Health Research Institute, Shunde Maternal and Children's Hospital, Guangdong Medical University, Shunde 528300, China.
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6
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Ma N, Xu E, Luo Q, Song G. Rac1: A Regulator of Cell Migration and A Potential Target for Cancer Therapy. Molecules 2023; 28:molecules28072976. [PMID: 37049739 PMCID: PMC10096471 DOI: 10.3390/molecules28072976] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 03/24/2023] [Accepted: 03/24/2023] [Indexed: 03/29/2023] Open
Abstract
Cell migration is crucial for physiological and pathological processes such as morphogenesis, wound repair, immune response and cancer invasion/metastasis. There are many factors affecting cell migration, and the regulatory mechanisms are complex. Rac1 is a GTP-binding protein with small molecular weight belonging to the Rac subfamily of the Rho GTPase family. As a key molecule in regulating cell migration, Rac1 participates in signal transduction from the external cell to the actin cytoskeleton and promotes the establishment of cell polarity which plays an important role in cancer cell invasion/metastasis. In this review, we firstly introduce the molecular structure and activity regulation of Rac1, and then summarize the role of Rac1 in cancer invasion/metastasis and other physiological processes. We also discuss the regulatory mechanisms of Rac1 in cell migration and highlight it as a potential target in cancer therapy. Finally, the current state as well as the future challenges in this area are considered. Understanding the role and the regulatory mechanism of Rac1 in cell migration can provide fundamental insights into Rac1-related cancer progression and further help us to develop novel intervention strategies for cancer therapy in clinic.
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Zhu X, Zhang F, You Y, Wang H, Yuan S, Wu B, Zhu R, Liu D, Yan F, Wang Z. S-Ketamine Exerts Antidepressant Effects by Regulating Rac1 GTPase Mediated Synaptic Plasticity in the Hippocampus of Stressed Rats. Cell Mol Neurobiol 2023; 43:299-314. [PMID: 35083636 DOI: 10.1007/s10571-021-01180-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 12/03/2021] [Indexed: 01/07/2023]
Abstract
Clinical studies have found that ketamine has a rapid and lasting antidepressant effect, especially in the case of patients with major depressive disorder (MDD). The molecular mechanisms, however, remain unclear. In this study, we observe the effects of S-Ketamine on the expression of Rac1, neuronal morphology, and synaptic transmission function in the hippocampus of stressed rats. Chronic unpredictable mild stress (CUMS) was used to construct stressed rats. The rats were given a different regimen of ketamine (20 mg/kg, i.p.) and Rac1 inhibitor NSC23766 (50 µg, ICV) treatment. The depression-like behavior of rats was evaluated by sucrose preference test and open-field test. The protein expression of Rac1, GluA1, synapsin1, and PSD95 in the hippocampus was detected by Western blot. Pull-down analysis was used to examine the activity of Rac1. Golgi staining and electrophysiological study were used to observe the neuronal morphology and long-term potentiation (LTP). Our results showed that ketamine can up-regulate the expression and activity of Rac1; increase the spine density and the expression of synaptic-related proteins such as GluA1, Synapsin1, and PSD95 in the hippocampus of stressed rats; reduce the CUMS-induced LTP impairments; and consequently improve depression-like behavior. However, Rac1 inhibitor NSC23766 could have effectively reversed ketamine-mediated changes in the hippocampus of rats and counteracted its antidepressant effects. The specific mechanism of S-Ketamine's antidepressant effect may be related to the up-regulation of the expression and activity of Rac1 in the hippocampus of stressed rats, thus enhancing synaptic plasticity.
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Affiliation(s)
- Xianlin Zhu
- Department of Anesthesiology, The Central Hospital of Enshi Tujia and Miao Autonomous Prefecture, Enshi City, 445000, Hubei Province, China
| | - Fan Zhang
- Department of Anesthesiology, Bishan Hospital, Bishan, Chongqing, 402760, China
| | - Yufeng You
- Department of Radiology, The Central Hospital of Enshi Tujia and Miao Autonomous Prefecture, Enshi City, 445000, Hubei Province, China
| | - Hongbai Wang
- Department of Anesthesiology, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100000, China
| | - Su Yuan
- Department of Anesthesiology, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100000, China
| | - Banglin Wu
- Department of Anesthesiology, The Central Hospital of Enshi Tujia and Miao Autonomous Prefecture, Enshi City, 445000, Hubei Province, China
| | - Rongyu Zhu
- Department of Anesthesiology, The Central Hospital of Enshi Tujia and Miao Autonomous Prefecture, Enshi City, 445000, Hubei Province, China
| | - Dawei Liu
- Department of Anesthesiology, Yongchuan Hospital of Chongqing Medical University, Chongqing, 402160, China
| | - Fuxia Yan
- Department of Anesthesiology, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100000, China.
| | - Zaiping Wang
- Department of Anesthesiology, The Central Hospital of Enshi Tujia and Miao Autonomous Prefecture, Enshi City, 445000, Hubei Province, China.
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8
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Jung G, Pan M, Alexander C, Jin T, Hammer JA. Dual regulation of the actin cytoskeleton by CARMIL-GAP. J Cell Sci 2022; 135:275754. [PMID: 35583107 PMCID: PMC9270954 DOI: 10.1242/jcs.258704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 05/09/2022] [Indexed: 11/29/2022] Open
Abstract
Capping protein Arp2/3 myosin I linker (CARMIL) proteins are multi-domain scaffold proteins that regulate actin dynamics by regulating the activity of capping protein (CP). Here, we characterize CARMIL-GAP (GAP for GTPase-activating protein), a Dictyostelium CARMIL isoform that contains a ∼130 residue insert that, by homology, confers GTPase-activating properties for Rho-related GTPases. Consistent with this idea, this GAP domain binds Dictyostelium Rac1a and accelerates its rate of GTP hydrolysis. CARMIL-GAP concentrates with F-actin in phagocytic cups and at the leading edge of chemotaxing cells, and CARMIL-GAP-null cells exhibit pronounced defects in phagocytosis and chemotactic streaming. Importantly, these defects are fully rescued by expressing GFP-tagged CARMIL-GAP in CARMIL-GAP-null cells. Finally, rescue with versions of CARMIL-GAP that lack either GAP activity or the ability to regulate CP show that, although both activities contribute significantly to CARMIL-GAP function, the GAP activity plays the bigger role. Together, our results add to the growing evidence that CARMIL proteins influence actin dynamics by regulating signaling molecules as well as CP, and that the continuous cycling of the nucleotide state of Rho GTPases is often required to drive Rho-dependent biological processes. Summary:Dictyostelium CARMIL-GAP supports phagocytosis and chemotaxis by regulating both capping protein and Rac1.
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Affiliation(s)
- Goeh Jung
- Cell and Developmental Biology Center, National Heart lung and Blood Institute, National Institutes of Health, USA
| | - Miao Pan
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Disease, National Institutes of Health, USA
| | - Chris Alexander
- Cell and Developmental Biology Center, National Heart lung and Blood Institute, National Institutes of Health, USA
| | - Tian Jin
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Disease, National Institutes of Health, USA
| | - John A Hammer
- Cell and Developmental Biology Center, National Heart lung and Blood Institute, National Institutes of Health, USA
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9
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Duman JG, Blanco FA, Cronkite CA, Ru Q, Erikson KC, Mulherkar S, Saifullah AB, Firozi K, Tolias KF. Rac-maninoff and Rho-vel: The symphony of Rho-GTPase signaling at excitatory synapses. Small GTPases 2022; 13:14-47. [PMID: 33955328 PMCID: PMC9707551 DOI: 10.1080/21541248.2021.1885264] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/22/2021] [Accepted: 01/28/2021] [Indexed: 01/15/2023] Open
Abstract
Synaptic connections between neurons are essential for every facet of human cognition and are thus regulated with extreme precision. Rho-family GTPases, molecular switches that cycle between an active GTP-bound state and an inactive GDP-bound state, comprise a critical feature of synaptic regulation. Rho-GTPases are exquisitely controlled by an extensive suite of activators (GEFs) and inhibitors (GAPs and GDIs) and interact with many different signalling pathways to fulfill their roles in orchestrating the development, maintenance, and plasticity of excitatory synapses of the central nervous system. Among the mechanisms that control Rho-GTPase activity and signalling are cell surface receptors, GEF/GAP complexes that tightly regulate single Rho-GTPase dynamics, GEF/GAP and GEF/GEF functional complexes that coordinate multiple Rho-family GTPase activities, effector positive feedback loops, and mutual antagonism of opposing Rho-GTPase pathways. These complex regulatory mechanisms are employed by the cells of the nervous system in almost every step of development, and prominently figure into the processes of synaptic plasticity that underlie learning and memory. Finally, misregulation of Rho-GTPases plays critical roles in responses to neuronal injury, such as traumatic brain injury and neuropathic pain, and in neurodevelopmental and neurodegenerative disorders, including intellectual disability, autism spectrum disorder, schizophrenia, and Alzheimer's Disease. Thus, decoding the mechanisms of Rho-GTPase regulation and function at excitatory synapses has great potential for combatting many of the biggest current challenges in mental health.
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Affiliation(s)
- Joseph G. Duman
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Francisco A. Blanco
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Integrative Molecular and Biomedical Science Graduate Program, Baylor College of Medicine, Houston, TX, USA
| | - Christopher A. Cronkite
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
- Medical Scientist Training Program, Baylor College of Medicine, Houston, TX, USA
| | - Qin Ru
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Kelly C. Erikson
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Shalaka Mulherkar
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Ali Bin Saifullah
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Karen Firozi
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Kimberley F. Tolias
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
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10
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Zhang H, Ben Zablah Y, Zhang H, Jia Z. Rho Signaling in Synaptic Plasticity, Memory, and Brain Disorders. Front Cell Dev Biol 2021; 9:729076. [PMID: 34671600 PMCID: PMC8520953 DOI: 10.3389/fcell.2021.729076] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 09/03/2021] [Indexed: 12/12/2022] Open
Abstract
Memory impairments are associated with many brain disorders such as autism, Alzheimer's disease, and depression. Forming memories involves modifications of synaptic transmission and spine morphology. The Rho family small GTPases are key regulators of synaptic plasticity by affecting various downstream molecules to remodel the actin cytoskeleton. In this paper, we will review recent studies on the roles of Rho proteins in the regulation of hippocampal long-term potentiation (LTP) and long-term depression (LTD), the most extensively studied forms of synaptic plasticity widely regarded as cellular mechanisms for learning and memory. We will also discuss the involvement of Rho signaling in spine morphology, the structural basis of synaptic plasticity and memory formation. Finally, we will review the association between brain disorders and abnormalities of Rho function. It is expected that studying Rho signaling at the synapse will contribute to the understanding of how memory is formed and disrupted in diseases.
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Affiliation(s)
- Haorui Zhang
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Youssif Ben Zablah
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Haiwang Zhang
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Zhengping Jia
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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11
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Solabre Valois L, Shi V(H, Bishop P, Zhu B, Nakamura Y, Wilkinson KA, Henley JM. Neurotrophic effects of Botulinum neurotoxin type A in hippocampal neurons involve activation of Rac1 by the non-catalytic heavy chain (HC C/A). IBRO Neurosci Rep 2021; 10:196-207. [PMID: 34041508 PMCID: PMC8143998 DOI: 10.1016/j.ibneur.2021.04.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 04/22/2021] [Indexed: 12/19/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are extremely potent naturally occurring poisons that act by silencing neurotransmission. Intriguingly, in addition to preventing presynaptic vesicle fusion, BoNT serotype A (BoNT/A) can also promote axonal regeneration in preclinical models. Here we report that the non-toxic C-terminal region of the receptor-binding domain of heavy chain BoNT/A (HCC/A) activates the small GTPase Rac1 and ERK pathway to potentiate axonal outgrowth, dendritic protrusion formation and synaptic vesicle release in hippocampal neurons. These data are consistent with HCC/A exerting neurotrophic properties, at least in part, independent of any BoNT catalytic activity or toxic effect.
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Affiliation(s)
- Luis Solabre Valois
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Vanilla (Hua) Shi
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Paul Bishop
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Bangfu Zhu
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Yasuko Nakamura
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Kevin A. Wilkinson
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
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12
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Semaphorin3F Drives Dendritic Spine Pruning Through Rho-GTPase Signaling. Mol Neurobiol 2021; 58:3817-3834. [PMID: 33856648 DOI: 10.1007/s12035-021-02373-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 03/24/2021] [Indexed: 12/18/2022]
Abstract
Dendritic spines of cortical pyramidal neurons are initially overproduced then remodeled substantially in the adolescent brain to achieve appropriate excitatory balance in mature circuits. Here we investigated the molecular mechanism of developmental spine pruning by Semaphorin 3F (Sema3F) and its holoreceptor complex, which consists of immunoglobulin-class adhesion molecule NrCAM, Neuropilin-2 (Npn2), and PlexinA3 (PlexA3) signaling subunits. Structure-function studies of the NrCAM-Npn2 interface showed that NrCAM stabilizes binding between Npn2 and PlexA3 necessary for Sema3F-induced spine pruning. Using a mouse neuronal culture system, we identified a dual signaling pathway for Sema3F-induced pruning, which involves activation of Tiam1-Rac1-PAK1-3 -LIMK1/2-Cofilin1 and RhoA-ROCK1/2-Myosin II in dendritic spines. Inhibitors of actin remodeling impaired spine collapse in the cortical neurons. Elucidation of these pathways expands our understanding of critical events that sculpt neuronal networks and may provide insight into how interruptions to these pathways could lead to spine dysgenesis in diseases such as autism, bipolar disorder, and schizophrenia.
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13
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Cheng J, Scala F, Blanco FA, Niu S, Firozi K, Keehan L, Mulherkar S, Froudarakis E, Li L, Duman JG, Jiang X, Tolias KF. The Rac-GEF Tiam1 Promotes Dendrite and Synapse Stabilization of Dentate Granule Cells and Restricts Hippocampal-Dependent Memory Functions. J Neurosci 2021; 41:1191-1206. [PMID: 33328293 PMCID: PMC7888217 DOI: 10.1523/jneurosci.3271-17.2020] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 11/25/2020] [Accepted: 12/01/2020] [Indexed: 12/14/2022] Open
Abstract
The dentate gyrus (DG) controls information flow into the hippocampus and is critical for learning, memory, pattern separation, and spatial coding, while DG dysfunction is associated with neuropsychiatric disorders. Despite its importance, the molecular mechanisms regulating DG neural circuit assembly and function remain unclear. Here, we identify the Rac-GEF Tiam1 as an important regulator of DG development and associated memory processes. In the hippocampus, Tiam1 is predominantly expressed in the DG throughout life. Global deletion of Tiam1 in male mice results in DG granule cells with simplified dendritic arbors, reduced dendritic spine density, and diminished excitatory synaptic transmission. Notably, DG granule cell dendrites and synapses develop normally in Tiam1 KO mice, resembling WT mice at postnatal day 21 (P21), but fail to stabilize, leading to dendrite and synapse loss by P42. These results indicate that Tiam1 promotes DG granule cell dendrite and synapse stabilization late in development. Tiam1 loss also increases the survival, but not the production, of adult-born DG granule cells, possibly because of greater circuit integration as a result of decreased competition with mature granule cells for synaptic inputs. Strikingly, both male and female mice lacking Tiam1 exhibit enhanced contextual fear memory and context discrimination. Together, these results suggest that Tiam1 is a key regulator of DG granule cell stabilization and function within hippocampal circuits. Moreover, based on the enhanced memory phenotype of Tiam1 KO mice, Tiam1 may be a potential target for the treatment of disorders involving memory impairments.SIGNIFICANCE STATEMENT The dentate gyrus (DG) is important for learning, memory, pattern separation, and spatial navigation, and its dysfunction is associated with neuropsychiatric disorders. However, the molecular mechanisms controlling DG formation and function remain elusive. By characterizing mice lacking the Rac-GEF Tiam1, we demonstrate that Tiam1 promotes the stabilization of DG granule cell dendritic arbors, spines, and synapses, whereas it restricts the survival of adult-born DG granule cells, which compete with mature granule cells for synaptic integration. Notably, mice lacking Tiam1 also exhibit enhanced contextual fear memory and context discrimination. These findings establish Tiam1 as an essential regulator of DG granule cell development, and identify it as a possible therapeutic target for memory enhancement.
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Affiliation(s)
- Jinxuan Cheng
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
| | - Federico Scala
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
| | - Francisco A Blanco
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
- Integrative Molecular and Biomedical Science Graduate Program, Baylor College of Medicine, Houston, Texas 77030
| | - Sanyong Niu
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
| | - Karen Firozi
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
| | - Laura Keehan
- Department of Biosciences, Rice University, Houston, Texas 77005
| | - Shalaka Mulherkar
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
| | | | - Lingyong Li
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
| | - Joseph G Duman
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
| | - Xiaolong Jiang
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas 77030
| | - Kimberley F Tolias
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
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14
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Saneyoshi T. Reciprocal activation within a kinase effector complex: A mechanism for the persistence of molecular memory. Brain Res Bull 2021; 170:58-64. [PMID: 33556559 DOI: 10.1016/j.brainresbull.2021.01.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 01/10/2021] [Accepted: 01/25/2021] [Indexed: 01/01/2023]
Abstract
Synaptic connections in neuronal circuits change in response to neuronal activity patterns. This can induce a persistent change in the efficacy of synaptic transmission, a phenomenon known as synaptic plasticity. One form of plasticity, long-term potentiation (LTP) has been extensively studied as the cellular basis of memory. In LTP, the potentiated synaptic transmission persists along with structural changes in the synapses. Many studies have sought to identify the "memory molecule" or the "molecular engram". Ca2+/calmodulin-dependent protein kinase II (CaMKII) is probably the most well-studied candidate for the memory molecule. However, consensus has not yet been reached on a very basic aspect: how CaMKII is regulated during LTP. Here, I propose a new model of CaMKII regulation: reciprocal activation within a kinase effector complex (RAKEC) that is made between CaMKII and its effector protein, which is mediated by a persistent interaction between CaMKII and a pseudosubstrate sequence on T-lymphoma invasion and metastasis protein 1 (Tiam1), resulting in reciprocal activation of these two molecules. Through the RAKEC mechanism, CaMKII can maintain memory as biochemical activity in a synapse-specific manner. In this review, the detailed mechanism of the RAKEC and its expansion for the maintenance of LTP is described.
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Affiliation(s)
- Takeo Saneyoshi
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan.
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15
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Lavanderos B, Silva I, Cruz P, Orellana-Serradell O, Saldías MP, Cerda O. TRP Channels Regulation of Rho GTPases in Brain Context and Diseases. Front Cell Dev Biol 2020; 8:582975. [PMID: 33240883 PMCID: PMC7683514 DOI: 10.3389/fcell.2020.582975] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 10/05/2020] [Indexed: 12/13/2022] Open
Abstract
Neurological and neuropsychiatric disorders are mediated by several pathophysiological mechanisms, including developmental and degenerative abnormalities caused primarily by disturbances in cell migration, structural plasticity of the synapse, and blood-vessel barrier function. In this context, critical pathways involved in the pathogenesis of these diseases are related to structural, scaffolding, and enzymatic activity-bearing proteins, which participate in Ca2+- and Ras Homologs (Rho) GTPases-mediated signaling. Rho GTPases are GDP/GTP binding proteins that regulate the cytoskeletal structure, cellular protrusion, and migration. These proteins cycle between GTP-bound (active) and GDP-bound (inactive) states due to their intrinsic GTPase activity and their dynamic regulation by GEFs, GAPs, and GDIs. One of the most important upstream inputs that modulate Rho GTPases activity is Ca2+ signaling, positioning ion channels as pivotal molecular entities for Rho GTPases regulation. Multiple non-selective cationic channels belonging to the Transient Receptor Potential (TRP) family participate in cytoskeletal-dependent processes through Ca2+-mediated modulation of Rho GTPases. Moreover, these ion channels have a role in several neuropathological events such as neuronal cell death, brain tumor progression and strokes. Although Rho GTPases-dependent pathways have been extensively studied, how they converge with TRP channels in the development or progression of neuropathologies is poorly understood. Herein, we review recent evidence and insights that link TRP channels activity to downstream Rho GTPase signaling or modulation. Moreover, using the TRIP database, we establish associations between possible mediators of Rho GTPase signaling with TRP ion channels. As such, we propose mechanisms that might explain the TRP-dependent modulation of Rho GTPases as possible pathways participating in the emergence or maintenance of neuropathological conditions.
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Affiliation(s)
- Boris Lavanderos
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Santiago, Chile
| | - Ian Silva
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Santiago, Chile
| | - Pablo Cruz
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Santiago, Chile
| | - Octavio Orellana-Serradell
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Santiago, Chile
| | - María Paz Saldías
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Santiago, Chile
| | - Oscar Cerda
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Santiago, Chile.,The Wound Repair, Treatment and Health (WoRTH) Initiative, Santiago, Chile
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16
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An autism-linked missense mutation in SHANK3 reveals the modularity of Shank3 function. Mol Psychiatry 2020; 25:2534-2555. [PMID: 30610205 PMCID: PMC6609509 DOI: 10.1038/s41380-018-0324-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 10/09/2018] [Accepted: 11/14/2018] [Indexed: 12/18/2022]
Abstract
Genome sequencing has revealed an increasing number of genetic variations that are associated with neuropsychiatric disorders. Frequently, studies limit their focus to likely gene-disrupting mutations because they are relatively easy to interpret. Missense variants, instead, have often been undervalued. However, some missense variants can be informative for developing a more profound understanding of disease pathogenesis and ultimately targeted therapies. Here we present an example of this by studying a missense variant in a well-known autism spectrum disorder (ASD) causing gene SHANK3. We analyzed Shank3's in vivo phosphorylation profile and identified S685 as one phosphorylation site where one ASD-linked variant has been reported. Detailed analysis of this variant revealed a novel function of Shank3 in recruiting Abelson interactor 1 (ABI1) and the WAVE complex to the post-synaptic density (PSD), which is critical for synapse and dendritic spine development. This function was found to be independent of Shank3's other functions such as binding to GKAP and Homer. Introduction of this human ASD mutation into mice resulted in a small subset of phenotypes seen previously in constitutive Shank3 knockout mice, including increased allogrooming, increased social dominance, and reduced pup USV. Together, these findings demonstrate the modularity of Shank3 function in vivo. This modularity further indicates that there is more than one independent pathogenic pathway downstream of Shank3 and correcting a single downstream pathway is unlikely to be sufficient for clear clinical improvement. In addition, this study illustrates the value of deep biological analysis of select missense mutations in elucidating the pathogenesis of neuropsychiatric phenotypes.
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17
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Carreira LAM, Tostevin F, Gerland U, Søgaard-Andersen L. Protein-protein interaction network controlling establishment and maintenance of switchable cell polarity. PLoS Genet 2020; 16:e1008877. [PMID: 32569324 PMCID: PMC7332107 DOI: 10.1371/journal.pgen.1008877] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 07/02/2020] [Accepted: 05/21/2020] [Indexed: 11/19/2022] Open
Abstract
Cell polarity underlies key processes in all cells, including growth, differentiation and division. In the bacterium Myxococcus xanthus, front-rear polarity is crucial for motility. Notably, this polarity can be inverted, independent of the cell-cycle, by chemotactic signaling. However, a precise understanding of the protein network that establishes polarity and allows for its inversion has remained elusive. Here, we use a combination of quantitative experiments and data-driven theory to unravel the complex interplay between the three key components of the M. xanthus polarity module. By studying each of these components in isolation and their effects as we systematically reconstruct the system, we deduce the network of effective interactions between the polarity proteins. RomR lies at the root of this network, promoting polar localization of the other components, while polarity arises from interconnected negative and positive feedbacks mediated by the small GTPase MglA and its cognate GAP MglB, respectively. We rationalize this network topology as operating as a spatial toggle switch, providing stable polarity for persistent cell movement whilst remaining responsive to chemotactic signaling and thus capable of polarity inversions. Our results have implications not only for the understanding of polarity and motility in M. xanthus but also, more broadly, for dynamic cell polarity. The asymmetric localization of cellular components (polarity) is at the core of many important cellular functions including growth, division, differentiation and motility. However, important questions still remain regarding the design principles underlying polarity networks and how their activity can be controlled in space and time. We use the rod-shaped bacterium Myxococcus xanthus as a model to study polarity and its regulation. Like many bacteria, in M. xanthus a well-defined front-rear polarity axis enables efficient translocation. This polarity axis is defined by asymmetric polar localization of a switch-like GTPase and its cognate regulators, and can be reversed in response to signaling cues. Here we use a combination of quantitative experiments and data-driven theory to deduce the network of interactions among the M. xanthus polarity proteins and to show how the combination of positive- and negative-feedback interactions give rise to asymmetric polar protein localization. We rationalize this network topology as operating as a spatial toggle switch, providing stable polarity for persistent cell movement whilst remaining responsive to chemotactic signaling and capable of polarity inversions. Our results have broader implications for our understanding of dynamic cell polarity and GTPase regulation in both bacteria and eukaryotic cells.
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Affiliation(s)
| | - Filipe Tostevin
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- Physik-Department, Technische Universität München, James Franck Straße, Garching, Germany
| | - Ulrich Gerland
- Physik-Department, Technische Universität München, James Franck Straße, Garching, Germany
| | - Lotte Søgaard-Andersen
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- * E-mail:
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18
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Piras IS, Bleul C, Schrauwen I, Talboom J, Llaci L, De Both MD, Naymik MA, Halliday G, Bettencourt C, Holton JL, Serrano GE, Sue LI, Beach TG, Stefanova N, Huentelman MJ. Transcriptional profiling of multiple system atrophy cerebellar tissue highlights differences between the parkinsonian and cerebellar sub-types of the disease. Acta Neuropathol Commun 2020; 8:76. [PMID: 32493431 PMCID: PMC7268362 DOI: 10.1186/s40478-020-00950-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 05/19/2020] [Indexed: 01/04/2023] Open
Abstract
Multiple system atrophy (MSA) is a rare adult-onset neurodegenerative disease of unknown cause, with no effective therapeutic options, and no cure. Limited work to date has attempted to characterize the transcriptional changes associated with the disease, which presents as either predominating parkinsonian (MSA-P) or cerebellar (MSC-C) symptoms. We report here the results of RNA expression profiling of cerebellar white matter (CWM) tissue from two independent cohorts of MSA patients (n = 66) and healthy controls (HC; n = 66). RNA samples from bulk brain tissue and from oligodendrocytes obtained by laser capture microdissection (LCM) were sequenced. Differentially expressed genes (DEGs) were obtained and were examined before and after stratifying by MSA clinical sub-type.We detected the highest number of DEGs in the MSA-C group (n = 747) while only one gene was noted in MSA-P, highlighting the larger dysregulation of the transcriptome in the MSA-C CWM. Results from both bulk tissue and LCM analysis showed a downregulation of oligodendrocyte genes and an enrichment for myelination processes with a key role noted for the QKI gene. Additionally, we observed a significant upregulation of neuron-specific gene expression in MSA-C and enrichment for synaptic processes. A third cluster of genes was associated with the upregulation of astrocyte and endothelial genes, two cell types with a key role in inflammation processes. Finally, network analysis in MSA-C showed enrichment for β-amyloid related functional classes, including the known Alzheimer's disease (AD) genes, APP and PSEN1.This is the largest RNA profiling study ever conducted on post-mortem brain tissue from MSA patients. We were able to define specific gene expression signatures for MSA-C highlighting the different stages of the complex neurodegenerative cascade of the disease that included alterations in several cell-specific transcriptional programs. Finally, several results suggest a common transcriptional dysregulation between MSA and AD-related genes despite the clinical and neuropathological distinctions between the two diseases.
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19
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Mohan V, Sullivan CS, Guo J, Wade SD, Majumder S, Agarwal A, Anton ES, Temple BS, Maness PF. Temporal Regulation of Dendritic Spines Through NrCAM-Semaphorin3F Receptor Signaling in Developing Cortical Pyramidal Neurons. Cereb Cortex 2020; 29:963-977. [PMID: 29415226 DOI: 10.1093/cercor/bhy004] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Accepted: 01/06/2018] [Indexed: 01/03/2023] Open
Abstract
Neuron-glial related cell adhesion molecule NrCAM is a newly identified negative regulator of spine density that genetically interacts with Semaphorin3F (Sema3F), and is implicated in autism spectrum disorders (ASD). To investigate a role for NrCAM in spine pruning during the critical adolescent period when networks are established, we generated novel conditional, inducible NrCAM mutant mice (Nex1Cre-ERT2: NrCAMflox/flox). We demonstrate that NrCAM functions cell autonomously during adolescence in pyramidal neurons to restrict spine density in the visual (V1) and medial frontal cortex (MFC). Guided by molecular modeling, we found that NrCAM promoted clustering of the Sema3F holoreceptor complex by interfacing with Neuropilin-2 (Npn2) and PDZ scaffold protein SAP102. NrCAM-induced receptor clustering stimulated the Rap-GAP activity of PlexinA3 (PlexA3) within the holoreceptor complex, which in turn, inhibited Rap1-GTPase and inactivated adhesive β1 integrins, essential for Sema3F-induced spine pruning. These results define a developmental function for NrCAM in Sema3F receptor signaling that limits dendritic spine density on cortical pyramidal neurons during adolescence.
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Affiliation(s)
- Vishwa Mohan
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Chelsea S Sullivan
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Jiami Guo
- UNC Neuroscience Center and the Department of Cell Biology and Physiology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Sarah D Wade
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Samarpan Majumder
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Amit Agarwal
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, Goettingen, Germany
| | - Eva S Anton
- UNC Neuroscience Center and the Department of Cell Biology and Physiology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Brenda S Temple
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Patricia F Maness
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC, USA
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20
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Costa JF, Dines M, Lamprecht R. The Role of Rac GTPase in Dendritic Spine Morphogenesis and Memory. Front Synaptic Neurosci 2020; 12:12. [PMID: 32362820 PMCID: PMC7182350 DOI: 10.3389/fnsyn.2020.00012] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 03/04/2020] [Indexed: 11/21/2022] Open
Abstract
The ability to form memories in the brain is needed for daily functions, and its impairment is associated with human mental disorders. Evidence indicates that long-term memory (LTM)-related processes such as its consolidation, extinction and forgetting involve changes of synaptic efficacy produced by alterations in neural transmission and morphology. Modulation of the morphology and number of dendritic spines has been proposed to contribute to changes in neuronal transmission mediating such LTM-related processes. Rac GTPase activity is regulated by synaptic activation and it can affect spine morphology by controlling actin-regulatory proteins. Recent evidence shows that changes in Rac GTPase activity affect memory consolidation, extinction, erasure and forgetting and can affect spine morphology in brain areas that mediate these behaviors. Altered Rac GTPase activity is associated with abnormal spine morphology and brain disorders. By affecting Rac GTPase activity we can further understand the roles of spine morphogenesis in memory. Moreover, manipulation of Rac GTPase activity may serve as a therapeutic tool for the treatment of memory-related brain diseases.
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Affiliation(s)
| | | | - Raphael Lamprecht
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
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21
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Zheng CW, Zeng RJ, Xu LY, Li EM. Rho GTPases: Promising candidates for overcoming chemotherapeutic resistance. Cancer Lett 2020; 475:65-78. [PMID: 31981606 DOI: 10.1016/j.canlet.2020.01.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 01/17/2020] [Accepted: 01/17/2020] [Indexed: 02/06/2023]
Abstract
Despite therapeutic advances, resistance to chemotherapy remains a major challenge to patients with malignancies. Rho GTPases are essential for the development and progression of various diseases including cancer, and a vast number of studies have linked Rho GTPases to chemoresistance. Therefore, understanding the underlying mechanisms can expound the effects of Rho GTPases towards chemotherapeutic agents, and targeting Rho GTPases is a promising strategy to downregulate the chemo-protective pathways and overcome chemoresistance. Importantly, exceptions in certain biological conditions and interactions among the members of Rho GTPases should be noted. In this review, we focus on the role of Rho GTPases, particularly Rac1, in regulating chemoresistance and provide an overview of their related mechanisms and available inhibitors, which may offer novel options for future targeted cancer therapy.
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Affiliation(s)
- Chun-Wen Zheng
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou, 515041, China; The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou, 515041, China
| | - Rui-Jie Zeng
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou, 515041, China; The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou, 515041, China
| | - Li-Yan Xu
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou, 515041, China; Institute of Oncologic Pathology, Shantou University Medical College, Shantou, 515041, China.
| | - En-Min Li
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou, 515041, China; The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou, 515041, China.
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22
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Yang XY, Stanley RE, Ross AP, Robitaille AM, Gray JA, Cheyette BNR. Sestd1 Encodes a Developmentally Dynamic Synapse Protein That Complexes With BCR Rac1-GAP to Regulate Forebrain Dendrite, Spine and Synapse Formation. Cereb Cortex 2020; 29:505-516. [PMID: 29293918 DOI: 10.1093/cercor/bhx333] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 11/29/2017] [Indexed: 11/14/2022] Open
Abstract
SEC14 and Spectrin domain-1 (Sestd1) is a synapse protein that exhibits a striking shift from the presynaptic to postsynaptic space as neurons mature postnatally in the mouse hippocampus. Hippocampal pyramidal neurons from mice with global genetic deletion of Sestd1 have reduced dendrite arbors, spines, and excitatory synapses. Electrophysiologically this correlates with cell-autonomous reductions in both AMPA- and NMDA-excitatory postsynaptic currents in individual hippocampal neurons from which Sestd1 has been deleted in vivo. These neurodevelopmental and functional deficits are associated with increased activation of the Rho family GTPases Rac1 and RhoA. Co-immunoprecipitation and mass spectrometry reveal that the Breakpoint Cluster Region protein, a Rho GTPase activating protein (GAP), forms complexes with Sestd1 in brain tissue. This complements earlier findings that Sestd1 can also partner with other Rho family GAPs and guanine nucleotide exchange factors. Our findings demonstrate that Sestd1 is a developmentally dynamic synaptic regulator of Rho GTPases that contributes to dendrite and excitatory synapse formation within differentiating pyramidal neurons of the forebrain.
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Affiliation(s)
- Xiao Yong Yang
- Department of Psychiatry, University of California, San Francisco (UCSF), San Francisco, CA, USA
| | - Robert E Stanley
- Department of Psychiatry, University of California, San Francisco (UCSF), San Francisco, CA, USA
| | - Adam P Ross
- Department of Psychiatry, University of California, San Francisco (UCSF), San Francisco, CA, USA
| | - Aaron M Robitaille
- Department of Pharmacology, Institute for Stem Cell and Regenerative Medicine, University of Washington (UW), Seattle, WA, USA
| | - John A Gray
- Department of Neurology, Center for Neuroscience, University of California, Davis, CA, USA
| | - Benjamin N R Cheyette
- Department of Psychiatry, University of California, San Francisco (UCSF), San Francisco, CA, USA.,Graduate Programs in Neuroscience, Stem Cell & Developmental Biology, Biomedical Sciences, Tetrad, Pharmaceutical Sciences & Pharmacogenomics, UCSF, San Francisco, CA, USA
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23
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Zheng C, Wu X, Zeng R, Lin L, Xu L, Li E, Dong G. Computational Prediction of Hot Spots and Binding Site of Inhibitor NSC23766 on Rac1 Binding With Tiam1. Front Chem 2020; 8:625437. [PMID: 33604328 PMCID: PMC7884829 DOI: 10.3389/fchem.2020.625437] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 12/29/2020] [Indexed: 02/05/2023] Open
Abstract
Rac1 is a small signaling protein, which belongs to the Rho subfamily of Ras superfamily. It is activated by binding GTP and inactivated by exchanging GDP for GTP. The ability of nucleotide exchange depends on guanine nucleotide exchange factors (GEFs) family proteins. T-lymphoma invasion and metastasis factor 1 (Tiam1) is a member of GEFs. Rac1 participates in multiple signaling pathways and regulates various cellular events by interacting with GEFs. Particularly, it is involved in the development and progression of various kinds of tumors. In this paper, we have studied the detailed interaction between Rac1 and Tiam1. Seven residues on Rac1 are predicted to be important for the interaction with Tiam1, i.e. E31, Y32, D38, N39, Y64, D65 and W56. All these residues are located on the switch 1 and 2 domains which are the interface between Rac1 and Tiam1, except W56. In addition, we analyzed how inhibitor NSC23766 interacts with Rac1. Our docking results show that NSC23766 binds to the same region as Tiam1. Several residues, i.e. F37, D38, N39, W56, Y64, L67, L70 and S71, contribute much to binding free energy. These findings are very useful for the structure-based design of inhibitors toward Rac1.
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Affiliation(s)
| | - Xiaodong Wu
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou, China
- Medical Informatics Research Center, Shantou University Medical College, Shantou, China
| | - Ruijie Zeng
- Shantou University Medical College, Shantou, China
| | - Lirui Lin
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou, China
- Medical Informatics Research Center, Shantou University Medical College, Shantou, China
| | - Liyan Xu
- Key Laboratory of Molecular Biology in High Cancer Incidence Coastal Area of Guangdong Higher Education Institutes, Shantou University Medical College, Shantou, China
| | - Enmin Li
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou, China
- Key Laboratory of Molecular Biology in High Cancer Incidence Coastal Area of Guangdong Higher Education Institutes, Shantou University Medical College, Shantou, China
- *Correspondence: Enmin Li, ; Geng Dong,
| | - Geng Dong
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou, China
- Medical Informatics Research Center, Shantou University Medical College, Shantou, China
- *Correspondence: Enmin Li, ; Geng Dong,
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24
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Olayioye MA, Noll B, Hausser A. Spatiotemporal Control of Intracellular Membrane Trafficking by Rho GTPases. Cells 2019; 8:cells8121478. [PMID: 31766364 PMCID: PMC6952795 DOI: 10.3390/cells8121478] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 11/15/2019] [Accepted: 11/18/2019] [Indexed: 12/17/2022] Open
Abstract
As membrane-associated master regulators of cytoskeletal remodeling, Rho GTPases coordinate a wide range of biological processes such as cell adhesion, motility, and polarity. In the last years, Rho GTPases have also been recognized to control intracellular membrane sorting and trafficking steps directly; however, how Rho GTPase signaling is regulated at endomembranes is still poorly understood. In this review, we will specifically address the local Rho GTPase pools coordinating intracellular membrane trafficking with a focus on the endo- and exocytic pathways. We will further highlight the spatiotemporal molecular regulation of Rho signaling at endomembrane sites through Rho regulatory proteins, the GEFs and GAPs. Finally, we will discuss the contribution of dysregulated Rho signaling emanating from endomembranes to the development and progression of cancer.
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25
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Tiam1 is Critical for Glutamatergic Synapse Structure and Function in the Hippocampus. J Neurosci 2019; 39:9306-9315. [PMID: 31597723 DOI: 10.1523/jneurosci.1566-19.2019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 10/02/2019] [Accepted: 10/03/2019] [Indexed: 02/06/2023] Open
Abstract
Mounting evidence suggests numerous glutamatergic synapse subtypes exist in the brain, and that these subtypes are likely defined by unique molecular regulatory mechanisms. Recent work has identified substantial divergence of molecular composition between commonly studied Schaffer collateral synapses and perforant path-dentate gyrus (DG) synapses of the hippocampus. However, little is known about the molecular mechanisms that may confer unique properties to perforant path-DG synapses. Here we investigate whether the RhoGEF (Rho guanine-nucleotide exchange factor) protein Tiam1 plays a unique role in the regulation of glutamatergic synapses in dentate granule neurons using a combination of molecular, electrophysiological, and imaging approaches in rat entorhino-hippocampal slices of both sexes. We find that inhibition of Tiam1 function in dentate granule neurons reduces synaptic AMPA receptor function and causes dendritic spines to adopt an elongated filopodia-like morphology. We also find that Tiam1's support of perforant path-DG synapse function is dependent on its GEF domain and identify a potential role for the auto-inhibitory PH domain of Tiam1 in regulating Tiam1 function at these synapses. In marked contrast, reduced Tiam1 expression in CA1 pyramidal neurons produced no effect on glutamatergic synapse development. Together, these data identify a critical role for Tiam1 in the hippocampus and reveal a unique Tiam1-mediated molecular program of glutamatergic synapse regulation in dentate granule neurons.SIGNIFICANCE STATEMENT Several lines of evidence independently point to the molecular diversity of glutamatergic synapses in the brain. Rho guanine-nucleotide exchange factor (RhoGEF) proteins as powerful modulators of glutamatergic synapse function have also become increasingly appreciated in recent years. Here we investigate the synaptic regulatory role of the RhoGEF protein Tiam1, whose expression appears to be remarkably enriched in granule neurons of the dentate gyrus. We find that Tiam1 plays a critical role in the development of glutamatergic perforant path-dentate gyrus synapses, but not in commonly studied in Schaffer collateral-CA1 synapses. Together, these data reveal a unique RhoGEF-mediated molecular program of glutamatergic synapse regulation in dentate granule neurons.
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26
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Zeng R, Zheng C, Gu J, Zhang H, Xie L, Xu L, Li E. RAC1 inhibition reverses cisplatin resistance in esophageal squamous cell carcinoma and induces downregulation of glycolytic enzymes. Mol Oncol 2019; 13:2010-2030. [PMID: 31314174 PMCID: PMC6717762 DOI: 10.1002/1878-0261.12548] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 06/07/2019] [Accepted: 07/16/2019] [Indexed: 02/05/2023] Open
Abstract
Development of chemoresistance remains a major challenge in treating esophageal squamous cell carcinoma (ESCC) patients despite treatment advances. However, the role of RAC1 in chemoresistance of ESCC and the underlying mechanisms remain largely unknown. In this study, we found that higher levels of RAC1 expression were associated with poorer prognosis in ESCC patients. Enhanced RAC1 expression increased cell proliferation, migration, and chemoresistance in vitro. Combination therapy using RAC1 inhibitor EHop-016 and cisplatin significantly promoted cell viability inhibition, G2/M phase cycle arrest, and apoptosis when compared to each monotherapy. Mechanistically, glycolysis was significantly downregulated in the RAC1 inhibitor monotherapy group and the combination group via inhibiting AKT/FOXO3a signaling when compared to the control group. Moreover, the silencing of RAC1 inhibited AKT/FOXO3a signaling and cell glycolysis while the upregulation of RAC1 produced an opposite effect. In murine xenograft models, the tumor volume and the expression of glycolytic enzymes were significantly reduced in combination therapy when compared to each monotherapy group. Overall, our study demonstrates that targeting RAC1 with an inhibitor overcomes cisplatin resistance in ESCC by suppressing glycolytic enzymes, which provides a promising strategy for treatment of ESCC in clinical practice.
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Affiliation(s)
- Rui‐Jie Zeng
- Department of Biochemistry and Molecular BiologyShantou University Medical CollegeChina
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan AreaShantou University Medical CollegeChina
| | - Chun‐Wen Zheng
- Department of Biochemistry and Molecular BiologyShantou University Medical CollegeChina
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan AreaShantou University Medical CollegeChina
| | - Jing‐E Gu
- Department of Biochemistry and Molecular BiologyShantou University Medical CollegeChina
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan AreaShantou University Medical CollegeChina
| | - Hai‐Xia Zhang
- Department of Biochemistry and Molecular BiologyShantou University Medical CollegeChina
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan AreaShantou University Medical CollegeChina
| | - Lei Xie
- Department of Biochemistry and Molecular BiologyShantou University Medical CollegeChina
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan AreaShantou University Medical CollegeChina
| | - Li‐Yan Xu
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan AreaShantou University Medical CollegeChina
- Institute of Oncologic PathologyShantou University Medical CollegeChina
| | - En‐Min Li
- Department of Biochemistry and Molecular BiologyShantou University Medical CollegeChina
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan AreaShantou University Medical CollegeChina
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27
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Duman JG, Mulherkar S, Tu YK, Erikson KC, Tzeng CP, Mavratsas VC, Ho TSY, Tolias KF. The adhesion-GPCR BAI1 shapes dendritic arbors via Bcr-mediated RhoA activation causing late growth arrest. eLife 2019; 8:47566. [PMID: 31461398 PMCID: PMC6713510 DOI: 10.7554/elife.47566] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 08/03/2019] [Indexed: 12/17/2022] Open
Abstract
Dendritic arbor architecture profoundly impacts neuronal connectivity and function, and aberrant dendritic morphology characterizes neuropsychiatric disorders. Here, we identify the adhesion-GPCR BAI1 as an important regulator of dendritic arborization. BAI1 loss from mouse or rat hippocampal neurons causes dendritic hypertrophy, whereas BAI1 overexpression precipitates dendrite retraction. These defects specifically manifest as dendrites transition from growth to stability. BAI1-mediated growth arrest is independent of its Rac1-dependent synaptogenic function. Instead, BAI1 couples to the small GTPase RhoA, driving late RhoA activation in dendrites coincident with growth arrest. BAI1 loss lowers RhoA activation and uncouples it from dendrite dynamics, causing overgrowth. None of BAI1's known downstream effectors mediates BAI1-dependent growth arrest. Rather, BAI1 associates with the Rho-GTPase regulatory protein Bcr late in development and stimulates its cryptic RhoA-GEF activity, which functions together with its Rac1-GAP activity to terminate arborization. Our results reveal a late-acting signaling pathway mediating a key transition in dendrite development.
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Affiliation(s)
- Joseph G Duman
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Shalaka Mulherkar
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Yen-Kuei Tu
- Graduate Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, United States
| | - Kelly C Erikson
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Christopher P Tzeng
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Vasilis C Mavratsas
- Department of Neuroscience, Baylor College of Medicine, Houston, United States.,Rice University, Houston, United States
| | - Tammy Szu-Yu Ho
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States
| | - Kimberley F Tolias
- Department of Neuroscience, Baylor College of Medicine, Houston, United States.,Graduate Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, United States.,Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, United States
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28
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Saneyoshi T, Matsuno H, Suzuki A, Murakoshi H, Hedrick NG, Agnello E, O'Connell R, Stratton MM, Yasuda R, Hayashi Y. Reciprocal Activation within a Kinase-Effector Complex Underlying Persistence of Structural LTP. Neuron 2019; 102:1199-1210.e6. [PMID: 31078368 DOI: 10.1016/j.neuron.2019.04.012] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 12/07/2018] [Accepted: 04/03/2019] [Indexed: 10/26/2022]
Abstract
Long-term synaptic plasticity requires a mechanism that converts short Ca2+ pulses into persistent biochemical signaling to maintain changes in the synaptic structure and function. Here, we present a novel mechanism of a positive feedback loop, formed by a reciprocally activating kinase-effector complex (RAKEC) in dendritic spines, enabling the persistence and confinement of a molecular memory. We found that stimulation of a single spine causes the rapid formation of a RAKEC consisting of CaMKII and Tiam1, a Rac-GEF. This interaction is mediated by a pseudo-autoinhibitory domain on Tiam1, which is homologous to the CaMKII autoinhibitory domain itself. Therefore, Tiam1 binding results in constitutive CaMKII activation, which in turn persistently phosphorylates Tiam1. Phosphorylated Tiam1 promotes stable actin-polymerization through Rac1, thereby maintaining the structure of the spine during LTP. The RAKEC can store biochemical information in small subcellular compartments, thus potentially serving as a general mechanism for prolonged and compartmentalized signaling.
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Affiliation(s)
- Takeo Saneyoshi
- Brain Science Institute, RIKEN, Wako, Saitama 351-0198, Japan; Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan.
| | - Hitomi Matsuno
- Brain Science Institute, RIKEN, Wako, Saitama 351-0198, Japan
| | - Akio Suzuki
- Brain Science Institute, RIKEN, Wako, Saitama 351-0198, Japan
| | - Hideji Murakoshi
- National Institute of Physiological Science, Okazaki, Aichi 444-8585, Japan; Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA; Duke University Medical Center, Durham, NC 27703, USA
| | - Nathan G Hedrick
- Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA; Duke University Medical Center, Durham, NC 27703, USA
| | - Emily Agnello
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Rory O'Connell
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Margaret M Stratton
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Ryohei Yasuda
- Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA
| | - Yasunori Hayashi
- Brain Science Institute, RIKEN, Wako, Saitama 351-0198, Japan; Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan; Brain and Body System Science Institute, Saitama University, Saitama 338-8570, Japan; School of Life Science, South China Normal University, Guangzhou 510631, China.
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29
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Faralli JA, Desikan H, Peotter J, Kanneganti N, Weinhaus B, Filla MS, Peters DM. Genomic/proteomic analyses of dexamethasone-treated human trabecular meshwork cells reveal a role for GULP1 and ABR in phagocytosis. Mol Vis 2019; 25:237-254. [PMID: 31516309 PMCID: PMC6706170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 04/23/2019] [Indexed: 11/06/2022] Open
Abstract
Purpose The purpose of this study is to examine the expression profile of genes related to integrin-mediated phagocytosis that are altered by dexamethasone (DEX) and/or αvβ3 integrin signaling to gain a better understanding of the molecular basis of phagocytosis and the pathophysiology of glucocorticoid-induced ocular hypertension. Methods RNA and cell lysates were obtained from human trabecular meshwork (HTM) cells incubated with and without DEX for 4-5 d. The relative level of gene expression was evaluated using the Affymetrix Gene Chip® human gene microarray and quantitative PCR (qPCR). Changes in protein expression were validated using western blots or FACS analyses. The involvement of proteins in phagocytosis was determined using siRNA to knock down the expression of these proteins in an immortalized TM-1 cell line. Changes in the phagocytic activity were measured using pHrodo™-labeled S. aureus bioparticles followed by immunofluorescence microscopy. The effect of αvβ3 integrin expression and activity on GULP1 mRNA levels was measured using qPCR in TM-1 cells overexpressing wild type or constitutively active αvβ3 integrin. Results Gene microarrays revealed statistically significant differences (>2 fold) in the expression of seven genes known to be involved in phagocytosis. Three genes (CD36, ABR, and GULP1) were downregulated, while four genes (ITGB3, CHN1, PIK3R1, and MFGE8) were upregulated. The genes were either associated with modulating RAC1 activity (ABR and CHN1) or integrin signaling (CD36, GULP1, ITGB3, PIK3R1, and MFGE8). Another gene, SIRPA, was also downregulated (1.6 fold) but only in one cell strain. qPCR and western blot analyses verified that DEX caused a decrease in SIRPA and GULP1 mRNA and their protein levels, while levels of CHN1 mRNA and its protein were upregulated by DEX. qPCR showed that although ABR mRNA was downregulated compared to non-treated controls after 5 d of treatment with DEX, no change at the protein level was detected. qPCR analysis also revealed that DEX caused an increase in MFGE8 mRNA levels. The levels of CD36 mRNA and protein varied between cell strains treated with DEX and were not statistically different compared to controls. The knockdown of GULP1 and ABR using siRNAs decreased phagocytosis by 40%. Interestingly, GULP1 mRNA levels were also decreased by 60% when αvβ3 integrin was overexpressed in TM-1 cells. Conclusion The DEX-induced inhibition of phagocytosis may be caused by the downregulation of ABR and GULP1 disrupting the αvβ5 integrin/RAC1-mediated engulfment pathway. The downregulation of GULP1 by αvβ3 integrin further suggests that this integrin may be a negative regulator of phagocytosis by transcriptionally downregulating proteins needed for phagocytosis. In summary, these results represent new insights into the effects of glucocorticoids and integrin signaling on the phagocytic process in the TM.
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Affiliation(s)
- Jennifer A. Faralli
- Department of Pathology & Laboratory Medicine, University of Wisconsin, Madison, WI
| | - Harini Desikan
- Department of Pathology & Laboratory Medicine, University of Wisconsin, Madison, WI
| | - Jennifer Peotter
- Department of Pathology & Laboratory Medicine, University of Wisconsin, Madison, WI
| | - Nitin Kanneganti
- Department of Pathology & Laboratory Medicine, University of Wisconsin, Madison, WI
| | - Benjamin Weinhaus
- Department of Pathology & Laboratory Medicine, University of Wisconsin, Madison, WI
| | - Mark S. Filla
- Department of Pathology & Laboratory Medicine, University of Wisconsin, Madison, WI
| | - Donna M. Peters
- Department of Pathology & Laboratory Medicine, University of Wisconsin, Madison, WI,Department of Ophthalmology & Visual Sciences, University of Wisconsin, Madison, WI
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Obashi K, Matsuda A, Inoue Y, Okabe S. Precise Temporal Regulation of Molecular Diffusion within Dendritic Spines by Actin Polymers during Structural Plasticity. Cell Rep 2019; 27:1503-1515.e8. [DOI: 10.1016/j.celrep.2019.04.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 02/22/2019] [Accepted: 03/29/2019] [Indexed: 10/26/2022] Open
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31
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Chen YL, Wu WL, Jang CW, Yen YC, Wang SH, Tsai FY, Shen YY, Chen YW. Interferon-stimulated gene 15 modulates cell migration by interacting with Rac1 and contributes to lymph node metastasis of oral squamous cell carcinoma cells. Oncogene 2019; 38:4480-4495. [PMID: 30765861 DOI: 10.1038/s41388-019-0731-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 12/15/2018] [Accepted: 01/23/2019] [Indexed: 02/07/2023]
Abstract
In an effort to understand the underlying mechanisms of lymph node metastasis in oral squamous cell carcinoma (OSCC), through in vivo selection, LN1-1 cells were previously established from OEC-M1 cells and showed enhanced lymphangiogenesis and lymphatic metastasis capabilities. In the current study, we use a stable isotope labeling with amino acids in cell culture (SILAC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based proteomic platform to compare LN1-1 to OEC-M1 cells. Interferon-stimulated gene 15 (ISG15) was found highly expressed in LN1-1 cells. Immunohistochemical analysis and meta-analysis of publicly available microarray datasets revealed that the ISG15 level was increased in human OSCC tissues and associated with poor disease outcome. Knockdown of ISG15 had minimal effects on tumor growth but did decrease tumor lymphangiogenesis and lymphatic metastasis of LN1-1 cells. Consistent with the in vivo assay, ISG15 knockdown did not impair cell growth but diminished cell migration, invasion, and transendothelial migration in vitro. ISG15-induced cell migration was independent of ISGylation and associated with membrane protrusion. Ectopic expression of ISG15 increased Rac1 activity and knockdown of Rac1 impaired ISG15-enhanced migration. Furthermore, Rac1 colocalized with ISG15 to a region of membrane protrusion and ISG15 coimmunoprecipitated with Rac1, especially with the Rac1-GDP form. Importantly, as shown by proximity ligation assays, ISG15 and Rac1 physically interacted with each other. Our results indicated that ISG15 affects cell migration by interacting with Rac1 and regulating Rac1 activity and contributes to lymphatic metastasis in OSCC.
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Affiliation(s)
- Yu-Lin Chen
- National Institute of Cancer Research, National Health Research Institutes, Miaoli, Taiwan
| | - Wan-Lin Wu
- National Institute of Cancer Research, National Health Research Institutes, Miaoli, Taiwan
| | - Chuan-Wei Jang
- National Institute of Cancer Research, National Health Research Institutes, Miaoli, Taiwan
| | - Yi-Chen Yen
- National Institute of Cancer Research, National Health Research Institutes, Miaoli, Taiwan
| | - Ssu-Han Wang
- National Institute of Cancer Research, National Health Research Institutes, Miaoli, Taiwan
| | - Fang-Yu Tsai
- National Institute of Cancer Research, National Health Research Institutes, Miaoli, Taiwan
| | - Ying-Ying Shen
- Pathology Core Laboratory, National Health Research Institutes, Miaoli, Taiwan
| | - Ya-Wen Chen
- National Institute of Cancer Research, National Health Research Institutes, Miaoli, Taiwan. .,Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan.
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Csépányi-Kömi R, Pásztor M, Bartos B, Ligeti E. The neglected terminators: Rho family GAPs in neutrophils. Eur J Clin Invest 2018; 48 Suppl 2:e12993. [PMID: 29972685 DOI: 10.1111/eci.12993] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 07/02/2018] [Indexed: 12/13/2022]
Abstract
BACKGROUND GTPase-activating proteins (GAPs) accelerate the rate of hydrolysis of GTP bound to small GTPases, thereby limiting the prevalence and concentration of the active, GTP-bound form of these proteins. The large number of potential GAPs acting on members of the Rho family of small GTPases raises the question of specificity or redundancy. RESULTS In this review, we summarize experimental data obtained on the role of Rho family GAPs in neutrophils, highlight cases where more than one GAP is involved in a physiological function and show examples that GAPs can be involved not only in termination but also in initiation of cellular processes. We demonstrate that the expression-level regulation of GAPs may also occur in short-living cells such as neutrophils. Finally, we provide insight into the existence and structure of molecular complexes in which Rho family GAPs are involved. CONCLUSION GAPs play more complex and varied roles than being simple terminators of cellular processes.
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Affiliation(s)
| | - Máté Pásztor
- Department of Physiology, Semmelweis University, Budapest, Hungary
| | - Balázs Bartos
- Department of Physiology, Semmelweis University, Budapest, Hungary
| | - Erzsébet Ligeti
- Department of Physiology, Semmelweis University, Budapest, Hungary
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Huang GH, Guo L, Zhu L, Liu XD, Sun ZL, Li HJ, Xu NJ, Feng DF. Neuronal GAP-Porf-2 transduces EphB1 signaling to brake axon growth. Cell Mol Life Sci 2018; 75:4207-4222. [PMID: 29938386 PMCID: PMC11105709 DOI: 10.1007/s00018-018-2858-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 06/17/2018] [Accepted: 06/20/2018] [Indexed: 12/12/2022]
Abstract
Axonal outgrowth and guidance require numerous extracellular cues and intracellular mediators that transduce signals in the growth cone to regulate cytoskeletal dynamics. However, the way in which cytoskeletal effectors respond to these signals remains elusive. Here, we demonstrate that Porf-2, a neuron-expressed RhoGTPase-activating protein, plays an essential role in the inhibition of initial axon growth by restricting the expansion of the growth cone in a cell-autonomous manner. Furthermore, the EphB1 receptor is identified as an upstream controller that binds and regulates Porf-2 specifically upon extracellular ephrin-B stimulation. The activated EphB forward signal deactivates Rac1 through the GAP domain of Porf-2, which inhibits growth cone formation and brakes axon growth. Our results therefore provide a novel GAP that regulates axon growth and braking sequentially through Eph receptor-independent and Eph receptor-dependent pathways.
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Affiliation(s)
- Guo-Hui Huang
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, No. 280 Mo-He Road, Shanghai, 201900, China
- Department of Neurosurgery, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, 200072, China
- Institute of Traumatic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 201900, China
| | - Lin Guo
- Center for Brain Science Research, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Liang Zhu
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, No. 280 Mo-He Road, Shanghai, 201900, China
| | - Xian-Dong Liu
- Center for Brain Science Research, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Zhao-Liang Sun
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, No. 280 Mo-He Road, Shanghai, 201900, China
| | - Hong-Jiang Li
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, No. 280 Mo-He Road, Shanghai, 201900, China
| | - Nan-Jie Xu
- Center for Brain Science Research, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
- Key Laboratory of Cell Differentiation and Apoptosis of the Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
| | - Dong-Fu Feng
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, No. 280 Mo-He Road, Shanghai, 201900, China.
- Institute of Traumatic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 201900, China.
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34
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Mansilla A, Jordán-Álvarez S, Santana E, Jarabo P, Casas-Tintó S, Ferrús A. Molecular mechanisms that change synapse number. J Neurogenet 2018; 32:155-170. [DOI: 10.1080/01677063.2018.1506781] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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35
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Payapilly A, Malliri A. Compartmentalisation of RAC1 signalling. Curr Opin Cell Biol 2018; 54:50-56. [PMID: 29723737 DOI: 10.1016/j.ceb.2018.04.009] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 04/12/2018] [Accepted: 04/15/2018] [Indexed: 12/22/2022]
Abstract
RAC1 signalling has been implicated in a variety of dynamic cell biological processes that are orchestrated through regulated localisation and activation of RAC1. As a small GTPase, RAC1 switches between active and inactive states at various subcellular locations that include the plasma membrane, nucleus and mitochondria. Once activated, RAC1 interacts with a range of effectors that then mediate various biological functions. RAC1 is regulated by a large number of proteins that can promote its recruitment, activation, deactivation, or stability. RAC1 and its regulators are subject to various post-translational modifications that further fine tune RAC1 localisation, levels and activity. Developments in technologies have enabled the accurate detection of activated RAC1 during processes such as cell migration, invasion and DNA damage. Here, we highlight recent advances in our understanding of RAC1 regulation and function at specific subcellular sites.
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Affiliation(s)
- Aishwarya Payapilly
- Cell Signalling Group, Cancer Research UK Manchester Institute, The University of Manchester, Alderley Park, SK10 4TG, UK
| | - Angeliki Malliri
- Cell Signalling Group, Cancer Research UK Manchester Institute, The University of Manchester, Alderley Park, SK10 4TG, UK.
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Remorino A, De Beco S, Cayrac F, Di Federico F, Cornilleau G, Gautreau A, Parrini MC, Masson JB, Dahan M, Coppey M. Gradients of Rac1 Nanoclusters Support Spatial Patterns of Rac1 Signaling. Cell Rep 2018; 21:1922-1935. [PMID: 29141223 DOI: 10.1016/j.celrep.2017.10.069] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 09/18/2017] [Accepted: 10/18/2017] [Indexed: 01/03/2023] Open
Abstract
Rac1 is a small RhoGTPase switch that orchestrates actin branching in space and time and protrusion/retraction cycles of the lamellipodia at the cell front during mesenchymal migration. Biosensor imaging has revealed a graded concentration of active GTP-loaded Rac1 in protruding regions of the cell. Here, using single-molecule imaging and super-resolution microscopy, we show an additional supramolecular organization of Rac1. We find that Rac1 partitions and is immobilized into nanoclusters of 50-100 molecules each. These nanoclusters assemble because of the interaction of the polybasic tail of Rac1 with the phosphoinositide lipids PIP2 and PIP3. The additional interactions with GEFs and possibly GAPs, downstream effectors, and other partners are responsible for an enrichment of Rac1 nanoclusters in protruding regions of the cell. Our results show that subcellular patterns of Rac1 activity are supported by gradients of signaling nanodomains of heterogeneous molecular composition, which presumably act as discrete signaling platforms.
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Affiliation(s)
- Amanda Remorino
- Laboratoire Physico-Chimie, Institut Curie, CNRS UMR168, Paris-Science Lettres, Universite Pierre et Marie Curie-Paris 6, 75005 Paris, France
| | - Simon De Beco
- Laboratoire Physico-Chimie, Institut Curie, CNRS UMR168, Paris-Science Lettres, Universite Pierre et Marie Curie-Paris 6, 75005 Paris, France
| | - Fanny Cayrac
- Laboratoire Physico-Chimie, Institut Curie, CNRS UMR168, Paris-Science Lettres, Universite Pierre et Marie Curie-Paris 6, 75005 Paris, France
| | - Fahima Di Federico
- Laboratoire Physico-Chimie, Institut Curie, CNRS UMR168, Paris-Science Lettres, Universite Pierre et Marie Curie-Paris 6, 75005 Paris, France
| | - Gaetan Cornilleau
- Laboratoire Physico-Chimie, Institut Curie, CNRS UMR168, Paris-Science Lettres, Universite Pierre et Marie Curie-Paris 6, 75005 Paris, France
| | - Alexis Gautreau
- Ecole Polytechnique, Université Paris-Saclay, CNRS UMR7654, 91120 Palaiseau, France
| | - Maria Carla Parrini
- Institut Curie, Centre de Recherche, Paris Sciences Lettres, ART Group, Inserm U830, Paris 75005, France
| | - Jean-Baptiste Masson
- Decision and Bayesian Computation, Institut Pasteur, 25 Rue du Docteur Roux, Paris, 75015, France; Bioinformatics and Biostatistics Hub - C3BI, USR 3756 IP CNRS, Paris, France
| | - Maxime Dahan
- Laboratoire Physico-Chimie, Institut Curie, CNRS UMR168, Paris-Science Lettres, Universite Pierre et Marie Curie-Paris 6, 75005 Paris, France
| | - Mathieu Coppey
- Laboratoire Physico-Chimie, Institut Curie, CNRS UMR168, Paris-Science Lettres, Universite Pierre et Marie Curie-Paris 6, 75005 Paris, France.
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Das A, Dines M, Alapin JM, Lamprecht R. Affecting long-term fear memory formation through optical control of Rac1 GTPase and PAK activity in lateral amygdala. Sci Rep 2017; 7:13930. [PMID: 29066727 PMCID: PMC5655381 DOI: 10.1038/s41598-017-13674-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 09/26/2017] [Indexed: 02/03/2023] Open
Abstract
Fear conditioning, a behavioral model for studying fear-related disorders, is believed to be formed by alterations of synaptic efficacy mediated by changes in synaptic transmission and neuronal morphology in lateral amygdala (LA). Rac GTPase and its downstream effector p21-activated kinase (PAK) are involved in such key neuronal functions. Here we show that optical activation of Rac1 GTPase using photoactivatable form of Rac1 (PA-Rac1) in amygdala led to phosphorylation of PAK and inhibition of long-term but not short-term auditory fear conditioning memory formation. Activation of PA-Rac1 in LA one day after fear conditioning had no effect on long-term fear memory tested 24 hrs after PA-Rac1 activation. Inhibition of PAK in LA by microinjection of the PAK inhibitor IPA-3 30 minutes before fear conditioning enhanced long-term but not short-term fear memory formation. Our results demonstrate that photoactivation of Rac1 GTPase in lateral amygdala impairs fear memory formation. Moreover, Rac1 effector PAK activity during fear conditioning constrains the formation of fear memory in LA. Thus, Rac GTPase and PAK proteins may serve as targets for treatment of fear and anxiety disorders.
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Affiliation(s)
- Aniruddha Das
- Sagol Department of Neurobiology, Faculty of Natural Sciences,, Haifa, Israel
| | - Monica Dines
- Sagol Department of Neurobiology, Faculty of Natural Sciences,, Haifa, Israel
| | - Jessica M Alapin
- Sagol Department of Neurobiology, Faculty of Natural Sciences,, Haifa, Israel
| | - Raphael Lamprecht
- Sagol Department of Neurobiology, Faculty of Natural Sciences,, Haifa, Israel. .,The Integrated Brain and Behavior Research Center (IBBR), University of Haifa, Haifa, Israel.
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38
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Smith KR, Rajgor D, Hanley JG. Differential regulation of the Rac1 GTPase-activating protein (GAP) BCR during oxygen/glucose deprivation in hippocampal and cortical neurons. J Biol Chem 2017; 292:20173-20183. [PMID: 29046349 PMCID: PMC5724004 DOI: 10.1074/jbc.m117.796292] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 09/28/2017] [Indexed: 12/22/2022] Open
Abstract
Brain ischemia causes oxygen and glucose deprivation (OGD) in neurons, triggering a cascade of events leading to synaptic accumulation of glutamate. Excessive activation of glutamate receptors causes excitotoxicity and delayed cell death in vulnerable neurons. Following global cerebral ischemia, hippocampal CA1 pyramidal neurons are more vulnerable to injury than their cortical counterparts, but the mechanisms that underlie this difference are unclear. Signaling via Rho-family small GTPases, their upstream guanine nucleotide exchange factors, and GTPase-activating proteins (GAPs) is differentially dysregulated in response to OGD/ischemia in hippocampal and cortical neurons. Increased Rac1 activity caused by OGD/ischemia contributes to neuronal death in hippocampal neurons via diverse effects on NADPH oxidase activity and dendritic spine morphology. The Rac1 guanine nucleotide exchange factor Tiam1 mediates an OGD-induced increase in Rac1 activity in hippocampal neurons; however, the identity of an antagonistic GAP remains elusive. Here we show that the Rac1 GAP breakpoint cluster region (BCR) associates with NMDA receptors (NMDARs) along with Tiam1 and that this protein complex is more abundant in hippocampal compared with cortical neurons. Although total BCR is similar in the two neuronal types, BCR is more active in hippocampal compared with cortical neurons. OGD causes an NMDAR- and Ca2+-permeable AMPAR-dependent deactivation of BCR in hippocampal but not cortical neurons. BCR knockdown occludes OGD-induced Rac1 activation in hippocampal neurons. Furthermore, disrupting the Tiam1–NMDAR interaction with a fragment of Tiam1 blocks OGD-induced Tiam1 activation but has no effect on the deactivation of BCR. This work identifies BCR as a critical player in Rac1 regulation during OGD in hippocampal neurons.
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Affiliation(s)
- Katharine R Smith
- Centre for Synaptic Plasticity and School of Biochemistry, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom; Department of Pharmacology, University of Colorado Denver School of Medicine, Aurora, Colorado 80045.
| | - Dipen Rajgor
- Centre for Synaptic Plasticity and School of Biochemistry, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
| | - Jonathan G Hanley
- Centre for Synaptic Plasticity and School of Biochemistry, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
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39
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Fu AKY, Ip NY. Regulation of postsynaptic signaling in structural synaptic plasticity. Curr Opin Neurobiol 2017; 45:148-155. [DOI: 10.1016/j.conb.2017.05.016] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 04/28/2017] [Accepted: 05/12/2017] [Indexed: 02/05/2023]
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40
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Nascent Proteome Remodeling following Homeostatic Scaling at Hippocampal Synapses. Neuron 2017; 92:358-371. [PMID: 27764671 PMCID: PMC5078608 DOI: 10.1016/j.neuron.2016.09.058] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 09/16/2016] [Accepted: 09/27/2016] [Indexed: 12/16/2022]
Abstract
Homeostatic scaling adjusts the strength of synaptic connections up or down in response to large changes in input. To identify the landscape of proteomic changes that contribute to opposing forms of homeostatic plasticity, we examined the plasticity-induced changes in the newly synthesized proteome. Cultured rat hippocampal neurons underwent homeostatic up-scaling or down-scaling. We used BONCAT (bio-orthogonal non-canonical amino acid tagging) to metabolically label, capture, and identify newly synthesized proteins, detecting and analyzing 5,940 newly synthesized proteins using mass spectrometry and label-free quantitation. Neither up- nor down-scaling produced changes in the number of different proteins translated. Rather, up- and down-scaling elicited opposing translational regulation of several molecular pathways, producing targeted adjustments in the proteome. We discovered ∼300 differentially regulated proteins involved in neurite outgrowth, axon guidance, filopodia assembly, excitatory synapses, and glutamate receptor complexes. We also identified differentially regulated proteins that are associated with multiple diseases, including schizophrenia, epilepsy, and Parkinson's disease.
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41
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Ba W, Nadif Kasri N. RhoGTPases at the synapse: An embarrassment of choice. Small GTPases 2017; 8:106-113. [PMID: 27492682 PMCID: PMC5464131 DOI: 10.1080/21541248.2016.1206352] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 06/22/2016] [Accepted: 06/22/2016] [Indexed: 12/14/2022] Open
Abstract
Activity-dependent modifications in the strength of excitatory synapses are considered to be major cellular mechanisms that contribute to the plasticity of neuronal networks underlying learning and memory. Key mechanisms for the regulation of synaptic efficacy involve the dynamic changes in size and number of dendritic spines, as well as the synaptic incorporation and removal of AMPA-type glutamate receptors (AMPAr). As key regulators of the actin cytoskeleton, the Rho subfamily of GTP-binding proteins play a critical role in synaptic development and plasticity. They shuttle between the active GTP-bound form and the inactive GDP-bound form under the regulation of dedicated guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). More than 80 human GEFs and 70 GAPs have been identified, most of which are expressed in the brain with a specific spatial and temporal expression pattern. However, the function of most GEFs and GAPs in the brain has not been elucidated. In this review, we highlight the novel neuronal function of the synaptic RhoGAP ARHGAP12 and the ID-associated RhoGEF TRIO and further propose 3 possible approaches of neurons utilizing Rho GTPase regulatory proteins to accurately modulate synaptic function.
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Affiliation(s)
- W. Ba
- Department of Cognitive Neuroscience, Radboudumc, Nijmegen, the Netherlands
- Department of Human Genetics, Radboudumc, Nijmegen, the Netherlands
- Donders Institute for Brain, Cognition, and Behavior, Nijmegen, the Netherlands
| | - N. Nadif Kasri
- Department of Cognitive Neuroscience, Radboudumc, Nijmegen, the Netherlands
- Department of Human Genetics, Radboudumc, Nijmegen, the Netherlands
- Donders Institute for Brain, Cognition, and Behavior, Nijmegen, the Netherlands
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42
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Abstract
Rho family GTPase signaling regulates the actin cytoskeleton and is critical for behaviors that range from the cell to tissue-scale. A theme in Rho GTPase biology is that there are many more regulators, such as guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs), than GTPases themselves. Here, we review different, modular cases where GEFs and GAPs function together to elicit precise spatial and temporal control of signaling. We focus on examples from metazoan development, where precise regulation of Rho GTPases is critical for proper tissue form and function.
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Affiliation(s)
- Marlis Denk-Lobnig
- a Department of Biology , Massachusetts Institute of Technology , Cambridge , MA , USA
| | - Adam C Martin
- a Department of Biology , Massachusetts Institute of Technology , Cambridge , MA , USA
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43
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Hamilton AM, Lambert JT, Parajuli LK, Vivas O, Park DK, Stein IS, Jahncke JN, Greenberg ME, Margolis SS, Zito K. A dual role for the RhoGEF Ephexin5 in regulation of dendritic spine outgrowth. Mol Cell Neurosci 2017; 80:66-74. [PMID: 28185854 DOI: 10.1016/j.mcn.2017.02.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 02/01/2017] [Accepted: 02/04/2017] [Indexed: 12/28/2022] Open
Abstract
The outgrowth of new dendritic spines is closely linked to the formation of new synapses, and is thought to be a vital component of the experience-dependent circuit plasticity that supports learning. Here, we examined the role of the RhoGEF Ephexin5 in driving activity-dependent spine outgrowth. We found that reducing Ephexin5 levels increased spine outgrowth, and increasing Ephexin5 levels decreased spine outgrowth in a GEF-dependent manner, suggesting that Ephexin5 acts as an inhibitor of spine outgrowth. Notably, we found that increased neural activity led to a proteasome-dependent reduction in the levels of Ephexin5 in neuronal dendrites, which could facilitate the enhanced spine outgrowth observed following increased neural activity. Surprisingly, we also found that Ephexin5-GFP levels were elevated on the dendrite at sites of future new spines, prior to new spine outgrowth. Moreover, lowering neuronal Ephexin5 levels inhibited new spine outgrowth in response to both global increases in neural activity and local glutamatergic stimulation of the dendrite, suggesting that Ephexin5 is necessary for activity-dependent spine outgrowth. Our data support a model in which Ephexin5 serves a dual role in spinogenesis, acting both as a brake on overall spine outgrowth and as a necessary component in the site-specific formation of new spines.
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Affiliation(s)
- A M Hamilton
- Center for Neuroscience, University of California Davis, Davis, CA 95618, USA
| | - J T Lambert
- Center for Neuroscience, University of California Davis, Davis, CA 95618, USA
| | - L K Parajuli
- Center for Neuroscience, University of California Davis, Davis, CA 95618, USA
| | - O Vivas
- Center for Neuroscience, University of California Davis, Davis, CA 95618, USA
| | - D K Park
- Center for Neuroscience, University of California Davis, Davis, CA 95618, USA
| | - I S Stein
- Center for Neuroscience, University of California Davis, Davis, CA 95618, USA
| | - J N Jahncke
- Center for Neuroscience, University of California Davis, Davis, CA 95618, USA
| | - M E Greenberg
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - S S Margolis
- Department of Biological Chemistry, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - K Zito
- Center for Neuroscience, University of California Davis, Davis, CA 95618, USA.
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44
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Huang GH, Sun ZL, Li HJ, Feng DF. Rho GTPase-activating proteins: Regulators of Rho GTPase activity in neuronal development and CNS diseases. Mol Cell Neurosci 2017; 80:18-31. [PMID: 28163190 DOI: 10.1016/j.mcn.2017.01.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 01/06/2017] [Accepted: 01/29/2017] [Indexed: 12/22/2022] Open
Abstract
The Rho family of small GTPases was considered as molecular switches in regulating multiple cellular events, including cytoskeleton reorganization. The Rho GTPase-activating proteins (RhoGAPs) are one of the major families of Rho GTPase regulators. RhoGAPs were initially considered negative mediators of Rho signaling pathways via their GAP domain. Recent studies have demonstrated that RhoGAPs also regulate numerous aspects of neuronal development and are related to various neurodegenerative diseases in GAP-dependent and GAP-independent manners. Moreover, RhoGAPs are regulated through various mechanisms, such as phosphorylation. To date, approximately 70 RhoGAPs have been identified; however, only a small portion has been thoroughly investigated. Thus, the characterization of important RhoGAPs in the central nervous system is crucial to understand their spatiotemporal role during different stages of neuronal development. In this review, we summarize the current knowledge of RhoGAPs in the brain with an emphasis on their molecular function, regulation mechanism and disease implications in the central nervous system.
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Affiliation(s)
- Guo-Hui Huang
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China
| | - Zhao-Liang Sun
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China
| | - Hong-Jiang Li
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China
| | - Dong-Fu Feng
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China; Institute of Traumatic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China.
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45
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Martin-Vilchez S, Whitmore L, Asmussen H, Zareno J, Horwitz R, Newell-Litwa K. RhoGTPase Regulators Orchestrate Distinct Stages of Synaptic Development. PLoS One 2017; 12:e0170464. [PMID: 28114311 PMCID: PMC5256999 DOI: 10.1371/journal.pone.0170464] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 01/05/2017] [Indexed: 11/19/2022] Open
Abstract
Small RhoGTPases regulate changes in post-synaptic spine morphology and density that support learning and memory. They are also major targets of synaptic disorders, including Autism. Here we sought to determine whether upstream RhoGTPase regulators, including GEFs, GAPs, and GDIs, sculpt specific stages of synaptic development. The majority of examined molecules uniquely regulate either early spine precursor formation or later maturation. Specifically, an activator of actin polymerization, the Rac1 GEF β-PIX, drives spine precursor formation, whereas both FRABIN, a Cdc42 GEF, and OLIGOPHRENIN-1, a RhoA GAP, regulate spine precursor elongation. However, in later development, a novel Rac1 GAP, ARHGAP23, and RhoGDIs inactivate actomyosin dynamics to stabilize mature synapses. Our observations demonstrate that specific combinations of RhoGTPase regulatory proteins temporally balance RhoGTPase activity during post-synaptic spine development.
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Affiliation(s)
- Samuel Martin-Vilchez
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA, United States of America
| | - Leanna Whitmore
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA, United States of America
| | - Hannelore Asmussen
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA, United States of America
| | - Jessica Zareno
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA, United States of America
| | - Rick Horwitz
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA, United States of America
| | - Karen Newell-Litwa
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA, United States of America
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC, United States of America
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46
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Jiang W, Sheng C, Gu X, Liu D, Yao C, Gao S, Chen S, Huang Y, Huang W, Fang M. Suppression of Rac1 Signaling by Influenza A Virus NS1 Facilitates Viral Replication. Sci Rep 2016; 6:35041. [PMID: 27869202 PMCID: PMC5116764 DOI: 10.1038/srep35041] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 09/13/2016] [Indexed: 11/26/2022] Open
Abstract
Influenza A virus (IAV) is a major human pathogen with the potential to become pandemic. IAV contains only eight RNA segments; thus, the virus must fully exploit the host cellular machinery to facilitate its own replication. In an effort to comprehensively characterize the host machinery taken over by IAV in mammalian cells, we generated stable A549 cell lines with over-expression of the viral non-structural protein (NS1) to investigate the potential host factors that might be modulated by the NS1 protein. We found that the viral NS1 protein directly interacted with cellular Rac1 and facilitated viral replication. Further research revealed that NS1 down-regulated Rac1 activity via post-translational modifications. Therefore, our results demonstrated that IAV blocked Rac1-mediated host cell signal transduction through the NS1 protein to facilitate its own replication. Our findings provide a novel insight into the mechanism of IAV replication and indicate new avenues for the development of potential therapeutic targets.
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Affiliation(s)
- Wei Jiang
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Chunjie Sheng
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xiuling Gu
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Dong Liu
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Chen Yao
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Shijuan Gao
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Shuai Chen
- State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Yinghui Huang
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, China
| | - Wenlin Huang
- State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, Guangzhou 510060, China
- Key Laboratory of Tumor Targeted Drug in Guangdong Province, Guangzhou Double Bioproducts Co., Ltd., Guangzhou, China
| | - Min Fang
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- International College, University of Chinese Academy of Sciences, Beijing, China
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47
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Kwan V, Meka D, White S, Hung C, Holzapfel N, Walker S, Murtaza N, Unda B, Schwanke B, Yuen R, Habing K, Milsom C, Hope K, Truant R, Scherer S, Calderon de Anda F, Singh K. DIXDC1 Phosphorylation and Control of Dendritic Morphology Are Impaired by Rare Genetic Variants. Cell Rep 2016; 17:1892-1904. [DOI: 10.1016/j.celrep.2016.10.047] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 09/02/2016] [Accepted: 10/14/2016] [Indexed: 10/20/2022] Open
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48
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Ka M, Kook YH, Liao K, Buch S, Kim WY. Transactivation of TrkB by Sigma-1 receptor mediates cocaine-induced changes in dendritic spine density and morphology in hippocampal and cortical neurons. Cell Death Dis 2016; 7:e2414. [PMID: 27735948 PMCID: PMC5133986 DOI: 10.1038/cddis.2016.319] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 08/31/2016] [Accepted: 09/09/2016] [Indexed: 01/02/2023]
Abstract
Cocaine is a highly addictive narcotic associated with dendritic spine plasticity in the striatum. However, it remains elusive whether cocaine modifies spines in a cell type-specific or region-specific manner or whether it alters different types of synapses in the brain. In addition, there is a paucity of data on the regulatory mechanism(s) involved in cocaine-induced modification of spine density. In the current study, we report that cocaine exposure differentially alters spine density, spine morphology, and the types of synapses in hippocampal and cortical neurons. Cocaine exposure in the hippocampus resulted in increased spine density, but had no significant effect on cortical neurons. Although cocaine exposure altered spine morphology in both cell types, the patterns of spine morphology were distinct for each cell type. Furthermore, we observed that cocaine selectively affects the density of excitatory synapses. Intriguingly, in hippocampal neurons cocaine-mediated effects on spine density and morphology involved sigma-1 receptor (Sig-1 R) and its downstream TrkB signaling, which were not the case in cortical neurons. Furthermore, pharmacological inhibition of Sig-1 R prevented cocaine-induced TrkB activation in hippocampal neurons. Our findings reveal a novel mechanism by which cocaine induces selective changes in spine morphology, spine density, and synapse formation, and could provide insights into the cellular basis for the cognitive impairment observed in cocaine addicts.
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Affiliation(s)
- Minhan Ka
- Department of Developmental Neuroscience, Munroe-Meyer Institute, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Yeon-Hee Kook
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Ke Liao
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Shilpa Buch
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Woo-Yang Kim
- Department of Developmental Neuroscience, Munroe-Meyer Institute, University of Nebraska Medical Center, Omaha, NE 68198, USA
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49
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Abstract
Excitatory synaptic strengthening and the corresponding enlargement of dendritic spines are thought to be essential for learning and memory. In two recent Nature papers, Harward et al. (2016) and Hedrick et al. (2016) provide insight into the mechanisms that regulate these processes and illuminate the molecular basis of crosstalk between synapses.
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50
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Gaitanos TN, Koerner J, Klein R. Tiam-Rac signaling mediates trans-endocytosis of ephrin receptor EphB2 and is important for cell repulsion. J Cell Biol 2016; 214:735-52. [PMID: 27597758 PMCID: PMC5021091 DOI: 10.1083/jcb.201512010] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 08/09/2016] [Indexed: 11/26/2022] Open
Abstract
Cell repulsion requires trans-endocytosis of ephrin receptors at cell–cell contact sites, but the mechanisms underlying this process are unclear. Here, Gaitanos et al. show that Tiam–Rac signaling mediates trans-endocytosis of EphB2 and is necessary for cell repulsion. Ephrin receptors interact with membrane-bound ephrin ligands to regulate contact-mediated attraction or repulsion between opposing cells, thereby influencing tissue morphogenesis. Cell repulsion requires bidirectional trans-endocytosis of clustered Eph–ephrin complexes at cell interfaces, but the mechanisms underlying this process are poorly understood. Here, we identified an actin-regulating pathway allowing ephrinB+ cells to trans-endocytose EphB receptors from opposing cells. Live imaging revealed Rac-dependent F-actin enrichment at sites of EphB2 internalization, but not during vesicle trafficking. Systematic depletion of Rho family GTPases and their regulatory proteins identified the Rac subfamily and the Rac-specific guanine nucleotide exchange factor Tiam2 as key components of EphB2 trans-endocytosis, a pathway previously implicated in Eph forward signaling, in which ephrins act as in trans ligands of Eph receptors. However, unlike in Eph signaling, this pathway is not required for uptake of soluble ligands in ephrinB+ cells. We also show that this pathway is required for EphB2-stimulated contact repulsion. These results support the existence of a conserved pathway for EphB trans-endocytosis that removes the physical tether between cells, thereby enabling cell repulsion.
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Affiliation(s)
- Thomas N Gaitanos
- Department of Molecules-Signaling-Development, Max Planck Institute of Neurobiology, 82152 Munich-Martinsried, Germany
| | - Jorg Koerner
- Department of Molecules-Signaling-Development, Max Planck Institute of Neurobiology, 82152 Munich-Martinsried, Germany
| | - Ruediger Klein
- Department of Molecules-Signaling-Development, Max Planck Institute of Neurobiology, 82152 Munich-Martinsried, Germany
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