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Jenks KR, Cai Y, Nayan ME, Tsimring K, Li K, Zepeda JC, Heller GR, Delepine C, Shih J, Yuan S, Zhu Y, Wang Y, Duan Y, Fu AKY, Ku T, Yun DH, Chung K, Zhang C, Boyden ES, Mellios N, Sur M, Kan Ip JP. The noncoding circular RNA circHomer1 regulates developmental experience-dependent plasticity in mouse visual cortex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.19.603416. [PMID: 39091722 PMCID: PMC11291094 DOI: 10.1101/2024.07.19.603416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
Circular RNAs (circRNAs) are noncoding RNAs abundant in brain tissue, and many are derived from activity-dependent, linear mRNAs encoding for synaptic proteins, suggesting that circRNAs may directly or indirectly play a role in regulating synaptic development, plasticity, and function. However, it is unclear if the circular forms of these RNAs are similarly regulated by activity and what role these circRNAs play in developmental plasticity. Here, we employed transcriptome-wide analysis comparing differential expression of both mRNAs and circRNAs in juvenile mouse primary visual cortex (V1) following monocular deprivation (MD), a model of developmental plasticity. Among the differentially expressed mRNAs and circRNAs following 3-day MD, the circular and the activity-dependent linear forms of the Homer1 gene, circHomer1 and Homer1a respectively, were of interest as their expression changed in opposite directions: circHomer1 expression increased while the expression of Homer1a decreased following MD. Knockdown of circHomer1 prevented the depression of closed-eye responses normally observed after 3-day MD. circHomer1 -knockdown led to a reduction in average dendritic spine size prior to MD, but critically there was no further reduction after 3-day MD, consistent with impaired structural plasticity. circHomer1 - knockdown also prevented the reduction of surface AMPA receptors after 3-day MD. Synapse-localized puncta of the AMPA receptor endocytic protein Arc increased in volume after MD but were smaller in circHomer1 -knockdown neurons, suggesting that circHomer1 regulates plasticity through mechanisms of activity-dependent AMPA receptor endocytosis. Thus, activity-dependent circRNAs regulate developmental synaptic plasticity, and our findings highlight the essential role of circHomer1 in V1 plasticity induced by short-term MD. Significance Statement Circular RNAs (circRNAs) are a class of closed-loop RNAs formed through back- splicing of exon and/or intron junctions. Initially considered as byproducts of aberrant RNA splicing with limited function, recent studies have implicated circRNAs in various neurological disorders. Despite their abundant expression in the brain, the role of circRNAs in synaptic function and plasticity remain poorly understood. We conducted an in vivo transcriptome analysis of circRNAs whose expression was regulated by experience-dependent plasticity in visual cortex and found that circHomer1 , a circRNA derived from the Homer1 gene, is critical for functional plasticity in vivo . Developmentally regulated circHomer1 mediates synaptic plasticity via Arc-mediated endocytosis of AMPA receptors. Our findings demonstrate circRNA regulation during experience-dependent plasticity and reveal their functional significance and mechanism.
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Dou Y, Fei X, He X, Huan Y, Wei J, Wu X, Lyu W, Fei Z, Li X, Fei F. Homer1a reduces inflammatory response after retinal ischemia/reperfusion injury. Neural Regen Res 2024; 19:1608-1617. [PMID: 38051906 PMCID: PMC10883521 DOI: 10.4103/1673-5374.386490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 08/25/2023] [Indexed: 12/07/2023] Open
Abstract
Abstract
JOURNAL/nrgr/04.03/01300535-202407000-00042/figure1/v/2023-11-20T171125Z/r/image-tiff
Elevated intraocular pressure (IOP) is one of the causes of retinal ischemia/reperfusion injury, which results in NLRP3 inflammasome activation and leads to visual damage. Homer1a is reported to play a protective role in neuroinflammation in the cerebrum. However, the effects of Homer1a on NLRP3 inflammasomes in retinal ischemia/reperfusion injury caused by elevated IOP remain unknown. In our study, animal models were constructed using C57BL/6J and Homer1flox/
–/Homer1a+/
–/Nestin-Cre+/
– mice with elevated IOP-induced retinal ischemia/reperfusion injury. For in vitro experiments, the oxygen-glucose deprivation/reperfusion injury model was constructed with Müller cells. We found that Homer1a overexpression ameliorated the decreases in retinal thickness and Müller cell viability after ischemia/reperfusion injury. Furthermore, Homer1a knockdown promoted NF-κB P65Ser536 activation via caspase-8, NF-κB P65 nuclear translocation, NLRP3 inflammasome formation, and the production and processing of interleukin-1β and interleukin-18. The opposite results were observed with Homer1a overexpression. Finally, the combined administration of Homer1a protein and JSH-23 significantly inhibited the reduction in retinal thickness in Homer1flox/
–/Homer1a+/
–/Nestin-Cre+/
– mice and apoptosis in Müller cells after ischemia/reperfusion injury. Taken together, these studies demonstrate that Homer1a exerts protective effects on retinal tissue and Müller cells via the caspase-8/NF-κB P65/NLRP3 pathway after I/R injury.
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Affiliation(s)
- Yanan Dou
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Xiaowei Fei
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Xin He
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Yu Huan
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Jialiang Wei
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Xiuquan Wu
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Weihao Lyu
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Zhou Fei
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Xia Li
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Fei Fei
- Department of Ophthalmology, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
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3
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Fei X, Wang L, Dou YN, Fei F, Zhang Y, Lv W, He X, Wu X, Chao W, Chen H, Wei J, Gao D, Fei Z. Extracellular vesicle encapsulated Homer1a as novel nanotherapeutics against intracerebral hemorrhage in a mouse model. J Neuroinflammation 2024; 21:85. [PMID: 38582897 PMCID: PMC10999083 DOI: 10.1186/s12974-024-03088-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Accepted: 04/02/2024] [Indexed: 04/08/2024] Open
Abstract
Homer1a and A2 astrocytes are involved in the regulation of inflammation induced by intracerebral hemorrhage (ICH). However, there is no anticipated treatment strategy based on the anti-inflammatory effect of Homer1a and A2 astrocytes. Here, we successfully induced A2 astrocytes in vitro, and then we report an efficient method to prepare Homer1a+ EVs derived from A2 astrocytes which making it more stable, safe, and targetable to injured neurons. Homer1a+ EVs promotes the conversion of A1 to A2 astrocytes in ICH mice. Homer1a+ EVs inhibits activation and nuclear translocation of NF-κB, thereby regulating transcription of IL-17A in neurons. Homer1a+ EVs inhibits the RAGE/NF-κB/IL-17 signaling pathway and the binding ability of IL-17A: IL17-AR and RAGE: DIAPH1. In addition, Homer1a+ EVs ameliorates the pathology, behavior, and survival rate in GFAPCreHomer1fl/-Homer1a± and NestinCreRAGEfl/fl ICH mice. Our study provides a novel insight and potential for the clinical translation of Homer1a+ EVs in the treatment of ICH.
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Affiliation(s)
- Xiaowei Fei
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 127, Changle West Road, Xincheng District, , Shaanxi, 710032, China
| | - Li Wang
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 127, Changle West Road, Xincheng District, , Shaanxi, 710032, China
| | - Ya-Nan Dou
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 127, Changle West Road, Xincheng District, , Shaanxi, 710032, China
| | - Fei Fei
- Department of Ophthalmology, Xijing Hospital, Air Force Military Medical University, Xi'an, 710032, Shaanxi, China
| | - Yanyu Zhang
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 127, Changle West Road, Xincheng District, , Shaanxi, 710032, China
| | - Weihao Lv
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 127, Changle West Road, Xincheng District, , Shaanxi, 710032, China
| | - Xin He
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 127, Changle West Road, Xincheng District, , Shaanxi, 710032, China
| | - Xiuquan Wu
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 127, Changle West Road, Xincheng District, , Shaanxi, 710032, China
| | - Wangshu Chao
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 127, Changle West Road, Xincheng District, , Shaanxi, 710032, China
| | - Hongqing Chen
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 127, Changle West Road, Xincheng District, , Shaanxi, 710032, China
| | - Jialiang Wei
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 127, Changle West Road, Xincheng District, , Shaanxi, 710032, China.
| | - Dakuan Gao
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 127, Changle West Road, Xincheng District, , Shaanxi, 710032, China.
| | - Zhou Fei
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, No. 127, Changle West Road, Xincheng District, , Shaanxi, 710032, China.
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Huang Z. Evidence that Alzheimer's Disease Is a Disease of Competitive Synaptic Plasticity Gone Awry. J Alzheimers Dis 2024; 99:447-470. [PMID: 38669548 PMCID: PMC11119021 DOI: 10.3233/jad-240042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2024]
Abstract
Mounting evidence indicates that a physiological function of amyloid-β (Aβ) is to mediate neural activity-dependent homeostatic and competitive synaptic plasticity in the brain. I have previously summarized the lines of evidence supporting this hypothesis and highlighted the similarities between Aβ and anti-microbial peptides in mediating cell/synapse competition. In cell competition, anti-microbial peptides deploy a multitude of mechanisms to ensure both self-protection and competitor elimination. Here I review recent studies showing that similar mechanisms are at play in Aβ-mediated synapse competition and perturbations in these mechanisms underpin Alzheimer's disease (AD). Specifically, I discuss evidence that Aβ and ApoE, two crucial players in AD, co-operate in the regulation of synapse competition. Glial ApoE promotes self-protection by increasing the production of trophic monomeric Aβ and inhibiting its assembly into toxic oligomers. Conversely, Aβ oligomers, once assembled, promote the elimination of competitor synapses via direct toxic activity and amplification of "eat-me" signals promoting the elimination of weak synapses. I further summarize evidence that neuronal ApoE may be part of a gene regulatory network that normally promotes competitive plasticity, explaining the selective vulnerability of ApoE expressing neurons in AD brains. Lastly, I discuss evidence that sleep may be key to Aβ-orchestrated plasticity, in which sleep is not only induced by Aβ but is also required for Aβ-mediated plasticity, underlining the link between sleep and AD. Together, these results strongly argue that AD is a disease of competitive synaptic plasticity gone awry, a novel perspective that may promote AD research.
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Affiliation(s)
- Zhen Huang
- Departments of Neuroscience and Neurology, University of Wisconsin-Madison, Madison, WI, USA
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Saadh MJ, Castillo-Acobo RY, Baher H, Narayanan J, Palacios Garay JP, Yamaguchi MNV, Arias-Gonzáles JL, Cotrina-Aliaga JC, Akram SV, Lakshmaiya N, Amin AH, Mohany M, Al-Rejaie SS, Ahsan M, Bahrami A, Akhavan-Sigari R. The protective role of sulforaphane and Homer1a in retinal ischemia-reperfusion injury: Unraveling the neuroprotective interplay. Life Sci 2023; 329:121968. [PMID: 37487941 DOI: 10.1016/j.lfs.2023.121968] [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: 05/29/2023] [Revised: 07/10/2023] [Accepted: 07/18/2023] [Indexed: 07/26/2023]
Abstract
AIMS Retinal ischemia/reperfusion (I/R) injury is a common pathological basis for various ophthalmic diseases. This study aimed to investigate the potential of sulforaphane (SFN) and Homer1a in regulating cell apoptosis induced by retinal I/R injury and to explore the underlying regulatory mechanism between them. MATERIALS AND METHODS In in vivo experiments, C57BL/6J mice and Homer1flox/-/Homer1a+/-/Nestin-Cre+/- mice were used to construct retinal I/R injury models. In vitro experiments utilized the oxygen-glucose deprivation-reperfusion (OGD/R) injury model with primary retinal ganglion cells (RGCs). The effects of Homer1a and SFN on cell apoptosis were observed through pathological analyses, flow cytometry, and visual electrophysiological assessments. KEY FINDINGS We discovered that after OGD/R injury, apoptosis of RGCs and intracellular Ca2+ activity significantly increased. However, these changes were reversed upon the addition of SFN, and similar observations were reproduced in in vivo studies. Furthermore, both in vivo and in vitro studies confirmed the upregulation of Homer1a after I/R, which could be further enhanced by the administration of SFN. Moreover, upregulation of Homer1a resulted in a reduction in cell apoptosis and pro-apoptotic proteins, while downregulation of Homer1a had the opposite effect. Flash visual evoked potential, oscillatory potentials, and escape latency measurements in mice supported these findings. Furthermore, the addition of SFN strengthened the neuroprotective effects in the OGD/R + H+ group but weakened them in Homer1flox/-/Homer1a+/-/Nestin-Cre+/- mice. SIGNIFICANCE These results indicate that Homer1a plays a significant role in the therapeutic potential of sulforaphane for retinal I/R injury, thereby providing a theoretical basis for clinical treatment.
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Affiliation(s)
- Mohamed J Saadh
- Faculty of Pharmacy, Middle East University, Amman 11831, Jordan; Applied Science Research Center, Applied Science Private University, Amman 11152, Jordan
| | | | - Hala Baher
- Department of Radiology and Ultrasonography Techniques, College of Medical Techniques, Al-Farahidi University, Baghdad, Iraq
| | | | | | | | - José Luis Arias-Gonzáles
- Department of Social Sciences, Faculty of Social Studies, University of British Columbia, BC, Canada
| | | | - Shaik Vaseem Akram
- Uttaranchal Institute of Technology, Division of research and Innovation, Uttaranchal University, Dehradun, India
| | - Natrayan Lakshmaiya
- Department of Mechanical Engineering, Saveetha School of Engineering, SRM Institute of Science and Technology, Chennai, Tamil Nadu, India
| | - Ali H Amin
- Zoology Department, Faculty of Science, Mansoura University, Mansoura 35516, Egypt
| | - Mohamed Mohany
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, P.O. Box 55760, Riyadh 11451, Saudi Arabia
| | - Salim S Al-Rejaie
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, P.O. Box 55760, Riyadh 11451, Saudi Arabia
| | - Muhammad Ahsan
- Department of Measurements and Control Systems, Silesian University of Technology, Gliwice, 44-100, Poland; Joint Doctoral School, Silesian University of Technology, Akademicka 2A, Gliwice, 44-100, Poland.
| | - Abolfazl Bahrami
- Department of Cell Biology, Tuebingen University, Tuebingen, Germany; Biomedical Center for Systems Biology Science Munich, Ludwig-Maximilians-University, Munich, Germany.
| | - Reza Akhavan-Sigari
- Department of Health Care Management and Clinical Research, Collegium Humanum Warsaw, Poland; Department of Neurosurgery, University Medical Center Tuebingen, Germany
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6
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Li N, Liu Q, Zhang Y, Yang Z, Shi X, Gu Y. Cortical feedback modulates distinct critical period development in mouse visual thalamus. iScience 2022; 26:105752. [PMID: 36590174 PMCID: PMC9794980 DOI: 10.1016/j.isci.2022.105752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 11/15/2022] [Accepted: 12/03/2022] [Indexed: 12/12/2022] Open
Abstract
In primary visual cortex (V1), critical period for ocular dominance (OD) plasticity is a well-defined developmental stage to shape neuronal circuits based on visual experience. Recent studies showed that V1-like OD plasticity existed in mouse dorsal lateral geniculate nucleus (dLGN). It is still unclear what the exact time window is and how neural circuits contribute to OD plasticity in dLGN. Using in vivo electrophysiology, we defined a critical period for OD plasticity in dLGN from eye opening to puberty. There also existed an innate process of OD formation from contralateral to equal bias in dLGN binocular neurons. Instant V1 inactivation with muscimol had no effect on OD bias or plasticity. Short-term V1 inactivation with N-methyl-d-aspartate reversed the formation of equal OD bias, while long-term V1 inactivation retained dLGN development to an immature stage.
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Affiliation(s)
- Na Li
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Qiong Liu
- School of Life Sciences, Westlake University, Hangzhou 310000, China
| | - Yimu Zhang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Zhongyi Yang
- School of Basic Medicine, Fudan University, Shanghai 200032, China
| | - Xuefeng Shi
- Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Institute, Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300020, China
- Institute of Ophthalmology, Nankai University, Tianjin 300020, China
- Corresponding author
| | - Yu Gu
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
- Corresponding author
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7
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Group I Metabotropic Glutamate Receptors and Interacting Partners: An Update. Int J Mol Sci 2022; 23:ijms23020840. [PMID: 35055030 PMCID: PMC8778124 DOI: 10.3390/ijms23020840] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 01/09/2022] [Accepted: 01/10/2022] [Indexed: 12/21/2022] Open
Abstract
Group I metabotropic glutamate (mGlu) receptors (mGlu1/5 subtypes) are G protein-coupled receptors and are broadly expressed in the mammalian brain. These receptors play key roles in the modulation of normal glutamatergic transmission and synaptic plasticity, and abnormal mGlu1/5 signaling is linked to the pathogenesis and symptomatology of various mental and neurological disorders. Group I mGlu receptors are noticeably regulated via a mechanism involving dynamic protein-protein interactions. Several synaptic protein kinases were recently found to directly bind to the intracellular domains of mGlu1/5 receptors and phosphorylate the receptors at distinct amino acid residues. A variety of scaffolding and adaptor proteins also interact with mGlu1/5. Constitutive or activity-dependent interactions between mGlu1/5 and their interacting partners modulate trafficking, anchoring, and expression of the receptors. The mGlu1/5-associated proteins also finetune the efficacy of mGlu1/5 postreceptor signaling and mGlu1/5-mediated synaptic plasticity. This review analyzes the data from recent studies and provides an update on the biochemical and physiological properties of a set of proteins or molecules that interact with and thus regulate mGlu1/5 receptors.
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Wu XQ, Su N, Fei Z, Fei F. Homer signaling pathways as effective therapeutic targets for ischemic and traumatic brain injuries and retinal lesions. Neural Regen Res 2021; 17:1454-1461. [PMID: 34916418 PMCID: PMC8771115 DOI: 10.4103/1673-5374.330588] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Ischemic and traumatic insults to the central nervous system account for most serious acute and fatal brain injuries and are usually characterized by primary and secondary damage. Secondary damage presents the greatest challenge for medical staff; however, there are currently few effective therapeutic targets for secondary damage. Homer proteins are postsynaptic scaffolding proteins that have been implicated in ischemic and traumatic insults to the central nervous system. Homer signaling can exert either positive or negative effects during such insults, depending on the specific subtype of Homer protein. Homer 1b/c couples with other proteins to form postsynaptic densities, which form the basis of synaptic transmission, while Homer1a expression can be induced by harmful external factors. Homer 1c is used as a unique biomarker to reveal alterations in synaptic connectivity before and during the early stages of apoptosis in retinal ganglion cells, mediated or affected by extracellular or intracellular signaling or cytoskeletal processes. This review summarizes the structural features, related signaling pathways, and diverse roles of Homer proteins in physiological and pathological processes. Upregulating Homer1a or downregulating Homer1b/c may play a neuroprotective role in secondary brain injuries. Homer also plays an important role in the formation of photoreceptor synapses. These findings confirm the neuroprotective effects of Homer, and support the future design of therapeutic drug targets or gene therapies for ischemic and traumatic brain injuries and retinal disorders based on Homer proteins.
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Affiliation(s)
- Xiu-Quan Wu
- Department of Neurosurgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi Province, China
| | - Ning Su
- Department of Radiation Oncology, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi Province, China
| | - Zhou Fei
- Department of Neurosurgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi Province, China
| | - Fei Fei
- Department of Ophthalmology, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi Province, China
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9
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Bockaert J, Perroy J, Ango F. The Complex Formed by Group I Metabotropic Glutamate Receptor (mGluR) and Homer1a Plays a Central Role in Metaplasticity and Homeostatic Synaptic Scaling. J Neurosci 2021; 41:5567-5578. [PMID: 34193623 PMCID: PMC8244974 DOI: 10.1523/jneurosci.0026-21.2021] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 05/05/2021] [Accepted: 05/06/2021] [Indexed: 12/28/2022] Open
Abstract
G-protein-coupled receptors can be constitutively activated following physical interaction with intracellular proteins. The first example described was the constitutive activation of Group I metabotropic glutamate receptors (mGluR: mGluR1,5) following their interaction with Homer1a, an activity-inducible early-termination variant of the scaffolding protein Homer that lacks dimerization capacity (Ango et al., 2001). Homer1a disrupts the links, maintained by the long form of Homer (cross-linking Homers), between mGluR1,5 and the Shank-GKAP-PSD-95-ionotropic glutamate receptor network. Two characteristics of the constitutive activation of the Group I mGluR-Homer1a complex are particularly interesting: (1) it affects a large number of synapses in which Homer1a is upregulated following enhanced, long-lasting neuronal activity; and (2) it mainly depends on Homer1a protein turnover. The constitutively active Group I mGluR-Homer1a complex is involved in the two main forms of non-Hebbian neuronal plasticity: "metaplasticity" and "homeostatic synaptic scaling," which are implicated in a large series of physiological and pathologic processes. Those include non-Hebbian plasticity observed in visual system, synapses modulated by addictive drugs (rewarded synapses), chronically overactivated synaptic networks, normal sleep, and sleep deprivation.
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Affiliation(s)
- Joël Bockaert
- Institut de Génomique Fonctionnelle, Université Montpellier, Center National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, 34094 Montpellier, France
| | - Julie Perroy
- Institut de Génomique Fonctionnelle, Université Montpellier, Center National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, 34094 Montpellier, France
| | - Fabrice Ango
- Institut des Neurosciences de Montpellier, Université Montpellier, Center National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, 34295 Montpellier, France
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10
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Sipe GO, Petravicz J, Rikhye RV, Garcia R, Mellios N, Sur M. Astrocyte glutamate uptake coordinates experience-dependent, eye-specific refinement in developing visual cortex. Glia 2021; 69:1723-1735. [PMID: 33675674 DOI: 10.1002/glia.23987] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 02/17/2021] [Accepted: 02/24/2021] [Indexed: 12/25/2022]
Abstract
The uptake of glutamate by astrocytes actively shapes synaptic transmission, however its role in the development and plasticity of neuronal circuits remains poorly understood. The astrocytic glutamate transporter, GLT1 is the predominant source of glutamate clearance in the adult mouse cortex. Here, we examined the structural and functional development of the visual cortex in GLT1 heterozygous (HET) mice using two-photon microscopy, immunohistochemistry and slice electrophysiology. We find that though eye-specific thalamic axonal segregation is intact, binocular refinement in the primary visual cortex is disrupted. Eye-specific responses to visual stimuli in GLT1 HET mice show altered binocular matching, with abnormally high responses to ipsilateral compared to contralateral eye stimulation and a greater mismatch between preferred orientation selectivity of ipsilateral and contralateral eye responses. Furthermore, we observe an increase in dendritic spine density in the basal dendrites of layer 2/3 excitatory neurons suggesting aberrant spine pruning. Monocular deprivation induces atypical ocular dominance plasticity in GLT1 HET mice, with an unusual depression of ipsilateral open eye responses; however, this change in ipsilateral responses correlates well with an upregulation of GLT1 protein following monocular deprivation. These results demonstrate that a key function of astrocytic GLT1 function during development is the experience-dependent refinement of ipsilateral eye inputs relative to contralateral eye inputs in visual cortex.
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Affiliation(s)
- Grayson O Sipe
- Department of Brain and Cognitive Sciences, Picower Institute of Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Jeremy Petravicz
- Department of Brain and Cognitive Sciences, Picower Institute of Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Rajeev V Rikhye
- Department of Brain and Cognitive Sciences, Picower Institute of Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Rodrigo Garcia
- Department of Brain and Cognitive Sciences, Picower Institute of Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Nikolaos Mellios
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, New Mexico, USA.,Autophagy Inflammation and Metabolism (AIM) Center, Albuquerque, New Mexico, USA
| | - Mriganka Sur
- Department of Brain and Cognitive Sciences, Picower Institute of Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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11
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Kasamatsu T, Imamura K. Ocular dominance plasticity: Molecular mechanisms revisited. J Comp Neurol 2020; 528:3039-3074. [PMID: 32737874 DOI: 10.1002/cne.25001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 07/10/2020] [Indexed: 12/14/2022]
Abstract
Ocular dominance plasticity (ODP) is a type of cortical plasticity operating in visual cortex of mammals that are endowed with binocular vision based on the competition-driven disparity. Earlier, a molecular mechanism was proposed that catecholamines play an important role in the maintenance of ODP in kittens. Having survived the initial test, the hypothesis was further advanced to identify noradrenaline (NA) as a key factor that regulates ODP in the immature cortex. Later, the ODP-promoting effect of NA is extended to the adult with age-related limitations. Following the enhanced NA availability, the chain events downstream lead to the β-adrenoreceptor-induced cAMP accumulation, which in turn activates the protein kinase A. Eventually, the protein kinase translocates to the cell nucleus to activate cAMP responsive element binding protein (CREB). CREB is a cellular transcription factor that controls the transcription of various genes, underpinning neuronal plasticity and long-term memory. In the advent of molecular genetics in that various types of new tools have become available with relative ease, ODP research has lightly adopted in the rodent model the original concepts and methodologies. Here, after briefly tracing the strategic maturation of our quest, the review moves to the later development of the field, with the emphasis placed around the following issues: (a) Are we testing ODP per se? (b) What does monocular deprivation deprive of the immature cortex? (c) The critical importance of binocular competition, (d) What is the adult plasticity? (e) Excitation-Inhibition balance in local circuits, and (f) Species differences in the animal models.
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Affiliation(s)
- Takuji Kasamatsu
- Smith-Kettlewell Eye Research Institute, San Francisco, California, USA
| | - Kazuyuki Imamura
- Department of Systems Life Engineering, Maebashi Institute of Technology, Maebashi-shi, Gunma, Japan
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