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Inglebert Y, Wu PY, Tourbina-Kolomiets J, Dang CL, McKinney RA. Synaptopodin is required for long-term depression at Schaffer collateral-CA1 synapses. Mol Brain 2024; 17:17. [PMID: 38566234 PMCID: PMC10988887 DOI: 10.1186/s13041-024-01089-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 03/24/2024] [Indexed: 04/04/2024] Open
Abstract
Synaptopodin (SP), an actin-associated protein found in telencephalic neurons, affects activity-dependant synaptic plasticity and dynamic changes of dendritic spines. While being required for long-term depression (LTD) mediated by metabotropic glutamate receptor (mGluR-LTD), little is known about its role in other forms of LTD induced by low frequency stimulation (LFS-LTD) or spike-timing dependent plasticity (STDP). Using electrophysiology in ex vivo hippocampal slices from SP-deficient mice (SPKO), we show that absence of SP is associated with a deficit of LTD at Sc-CA1 synapses induced by LFS-LTD and STDP. As LTD is known to require AMPA- receptors internalization and IP3-receptors calcium signaling, we tested by western blotting and immunochemistry if there were changes in their expression which we found to be reduced. While we were not able to induce LTD, long-term potentiation (LTP), albeit diminished in SPKO, can be recovered by using a stronger stimulation protocol. In SPKO we found no differences in NMDAR, which are the primary site of calcium signalling to induce LTP. Our study shows, for the first time, the key role of the requirement of SP to allow induction of activity-dependant LTD at Sc-CA1 synapses.
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Affiliation(s)
- Yanis Inglebert
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada.
- Current address Department of Neurosciences, Montreal University, Montreal, Canada.
| | - Pei You Wu
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | | | - Cong Loc Dang
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada.
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2
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Wu PY, Ji L, De Sanctis C, Francesconi A, Inglebert Y, McKinney RA. Loss of synaptopodin impairs mGluR5 and protein synthesis-dependent mGluR-LTD at CA3-CA1 synapses. PNAS Nexus 2024; 3:pgae062. [PMID: 38384385 PMCID: PMC10879843 DOI: 10.1093/pnasnexus/pgae062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Accepted: 02/01/2024] [Indexed: 02/23/2024]
Abstract
Metabotropic glutamate receptor-dependent long-term depression (mGluR-LTD) is an important form of synaptic plasticity that occurs in many regions of the central nervous system and is the underlying mechanism for several learning paradigms. In the hippocampus, mGluR-LTD is manifested by the weakening of synaptic transmission and elimination of dendritic spines. Interestingly, not all spines respond or undergo plasticity equally in response to mGluR-LTD. A subset of dendritic spines containing synaptopodin (SP), an actin-associated protein is critical for mGluR-LTD and protects spines from elimination through mGluR1 activity. The precise cellular function of SP is still enigmatic and it is still unclear how SP contributes to the functional aspect of mGluR-LTD despite its modulation of the structural plasticity. In this study, we show that the lack of SP impairs mGluR-LTD by negatively affecting the mGluR5-dependent activity. Such impairment of mGluR5 activity is accompanied by a significant decrease of surface mGluR5 level in SP knockout (SPKO) mice. Intriguingly, the remaining mGluR-LTD becomes a protein synthesis-independent process in the SPKO and is mediated instead by endocannabinoid signaling. These data indicate that the postsynaptic protein SP can regulate the locus of expression of mGluR-LTD and provide insight into our understanding of spine/synapse-specific plasticity.
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Affiliation(s)
- Pei You Wu
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Linjia Ji
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Claudia De Sanctis
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY 10461, USA
| | - Anna Francesconi
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY 10461, USA
| | - Yanis Inglebert
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC H3G 1Y6, Canada
| | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC H3G 1Y6, Canada
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Dankner M, Maritan SM, Priego N, Kruck G, Nkili-Meyong A, Nadaf J, Zhuang R, Annis MG, Zuo D, Nowakowski A, Biondini M, Kiepas A, Mourcos C, Le P, Charron F, Inglebert Y, Savage P, Théret L, Guiot MC, McKinney RA, Muller WJ, Park M, Valiente M, Petrecca K, Siegel PM. Invasive growth of brain metastases is linked to CHI3L1 release from pSTAT3-positive astrocytes. Neuro Oncol 2024:noae013. [PMID: 38271182 DOI: 10.1093/neuonc/noae013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Indexed: 01/27/2024] Open
Abstract
BACKGROUND Compared to minimally invasive brain metastases (MI BrM), highly invasive (HI) lesions form abundant contacts with cells in the peritumoral brain parenchyma and are associated with poor prognosis. Reactive astrocytes (RAs) labeled by phosphorylated STAT3 (pSTAT3) have recently emerged as a promising therapeutic target for BrM. Here, we explore whether BrM invasion pattern is influenced by pSTAT3+ RAs and may serve as a predictive biomarker for STAT3 inhibition. METHODS We used immunohistochemistry to identify pSTAT3+ RAs in HI and MI human and patient-derived xenograft (PDX) BrM. Using PDX, syngeneic, and transgenic mouse models of HI and MI BrM, we assessed how pharmacological STAT3 inhibition or RA-specific STAT3 genetic ablation affected BrM growth in vivo. Cancer cell invasion was modeled in vitro using a brain slice-tumor co-culture assay. We performed single-cell RNA sequencing of human BrM and adjacent brain tissue. RESULTS RAs expressing pSTAT3 are situated at the brain-tumor interface and drive BrM invasive growth. HI BrM invasion pattern was associated with delayed growth in the context of STAT3 inhibition or genetic ablation. We demonstrate that pSTAT3+ RAs secrete Chitinase 3-like-1 (CHI3L1), which is a known STAT3 transcriptional target. Furthermore, single-cell RNA sequencing identified CHI3L1-expressing RAs in human HI BrM. STAT3 activation, or recombinant CHI3L1 alone, induced cancer cell invasion into the brain parenchyma using a brain slice-tumor plug co-culture assay. CONCLUSIONS Together, these data reveal that pSTAT3+ RA-derived CHI3L1 is associated with BrM invasion, implicating STAT3 and CHI3L1 as clinically relevant therapeutic targets for the treatment of HI BrM.
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Affiliation(s)
- Matthew Dankner
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC, Canada
- Department of Medicine, Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Sarah M Maritan
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC, Canada
- Department of Medicine, Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Neibla Priego
- Brain Metastasis Group, Spanish National Cancer Research Center (CNIO), Madrid, Spain
| | - Georgia Kruck
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC, Canada
| | - Andriniaina Nkili-Meyong
- Department of Neurology and Neurosurgery, Faculty of Medicine, McGill University, Montreal, QC, Canada
- Montreal Neurological Institute-Hospital, McGill University Health Centre, Montreal, QC, Canada
| | - Javad Nadaf
- Department of Neurology and Neurosurgery, Faculty of Medicine, McGill University, Montreal, QC, Canada
- Montreal Neurological Institute-Hospital, McGill University Health Centre, Montreal, QC, Canada
| | - Rebecca Zhuang
- Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Matthew G Annis
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC, Canada
| | - Dongmei Zuo
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC, Canada
| | - Alexander Nowakowski
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC, Canada
- Department of Medicine, Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Marco Biondini
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC, Canada
| | - Alexander Kiepas
- Cell Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Caitlyn Mourcos
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC, Canada
- Department of Medicine, Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Phuong Le
- Department of Neurology and Neurosurgery, Faculty of Medicine, McGill University, Montreal, QC, Canada
- Montreal Neurological Institute-Hospital, McGill University Health Centre, Montreal, QC, Canada
| | - Francois Charron
- Department of Pharmacology, McGill University, Montreal, QC, Canada
| | - Yanis Inglebert
- Department of Neurosciences, University of Montreal, Montreal, QC, Canada
| | - Paul Savage
- Department of Surgery, University of Toronto, Toronto, ON, Canada
| | - Louis Théret
- Research Institute of the University of Montreal (IRIC), Montreal, QC, Canada
| | - Marie-Christine Guiot
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC, Canada
- Department of Neurology and Neurosurgery, Faculty of Medicine, McGill University, Montreal, QC, Canada
- Montreal Neurological Institute-Hospital, McGill University Health Centre, Montreal, QC, Canada
- Department of Pathology, Faculty of Medicine, McGill University, Montreal, QC, Canada
| | - R Anne McKinney
- Department of Pharmacology, McGill University, Montreal, QC, Canada
| | - William J Muller
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC, Canada
- Department of Biochemistry, Faculty of Medicine, McGill University, Montreal, QC, Canada
| | - Morag Park
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC, Canada
- Department of Medicine, Division of Experimental Medicine, McGill University, Montreal, QC, Canada
- Department of Pathology, Faculty of Medicine, McGill University, Montreal, QC, Canada
- Department of Biochemistry, Faculty of Medicine, McGill University, Montreal, QC, Canada
| | - Manuel Valiente
- Brain Metastasis Group, Spanish National Cancer Research Center (CNIO), Madrid, Spain
| | - Kevin Petrecca
- Department of Neurology and Neurosurgery, Faculty of Medicine, McGill University, Montreal, QC, Canada
- Montreal Neurological Institute-Hospital, McGill University Health Centre, Montreal, QC, Canada
| | - Peter M Siegel
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC, Canada
- Department of Medicine, Division of Experimental Medicine, McGill University, Montreal, QC, Canada
- Department of Biochemistry, Faculty of Medicine, McGill University, Montreal, QC, Canada
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Wu PY, Ji L, De Sanctis C, Francesconi A, Inglebert Y, McKinney RA. Loss of synaptopodin impairs mGluR5 and protein synthesis dependent mGluR-LTD at CA3-CA1 synapses. bioRxiv 2023:2023.08.02.551676. [PMID: 37577654 PMCID: PMC10418280 DOI: 10.1101/2023.08.02.551676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Metabotropic glutamate receptor-dependent long-term depression (mGluR-LTD) is an important form of synaptic plasticity that occurs in many regions of the CNS and is the underlying mechanism for several learning paradigms. In the hippocampus, mGluR-LTD is manifested by the weakening of synaptic transmission and elimination of dendritic spines. Interestingly, not all spines respond or undergo plasticity equally in response to mGluR-LTD. A subset of dendritic spines containing synaptopodin (SP), an actin-associated protein, are critical for mGluR-LTD and protect spines from elimination through mGluR1 activity. The precise cellular function of SP is still enigmatic and it is still unclear how SP contributes to the functional aspect of mGluR-LTD despite of its modulation on the structural plasticity. In the present study, we show that the lack of SP impairs mGluR-LTD by negatively affecting the mGluR5-dependent activity. Such impairment of mGluR5 activity is accompanied by a significant decrease of surface mGluR5 level in SP knockout (SPKO) mice. Intriguingly, the remaining mGluR-LTD becomes a protein synthesis-independent process in the SPKO and is mediated instead by endocannabinoid signaling. These data show for the first time that the postsynaptic protein SP can regulate the locus of expression of mGluR-LTD and provide insight to our understanding of spine/synapse-specific plasticity. Significance statement Hippocampal group I metabotropic glutamate receptor dependent long-term depression (mGluR-LTD), a form of learning and memory, is misregulated in many murine models of neurodevelopmental disorders. Despite extensive studies there is a paucity of information on the molecular mechanism underlying mGluR-LTD. Previously, we reported that loss of synaptopodin, an actin-associated protein found in a subset of mature dendritic spines, impairs mGluR-LTD. In the current study, we uncover the molecular and cellular deficits involved. We find that synaptopodin is required for the mGluR5-Homer interaction and uncover synaptopodin as a molecular switch for mGluR-LTD expression, as mGluR-LTD becomes protein synthesis-independent and relies on endocannabinoid signaling in synaptopodin knock-out. This work provides insight into synaptopodin as a gatekeeper to regulate mGluR-LTD at hippocampal synapses.
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Márquez BT, Leung TCS, Hui J, Charron F, McKinney RA, Watt AJ. A mitochondrial-targeted antioxidant (MitoQ) improves motor coordination and reduces Purkinje cell death in a mouse model of ARSACS. Neurobiol Dis 2023; 183:106157. [PMID: 37209925 DOI: 10.1016/j.nbd.2023.106157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 05/10/2023] [Accepted: 05/17/2023] [Indexed: 05/22/2023] Open
Abstract
Mitochondrial deficits have been observed in animal models of Autosomal-recessive spastic ataxia of the Charlevoix-Saguenay (ARSACS) and in patient-derived fibroblasts. We investigated whether mitochondrial function could be restored in Sacs-/- mice, a mouse model of ARSACS, using the mitochondrial-targeted antioxidant ubiquinone MitoQ. After 10 weeks of chronic MitoQ administration in drinking water, we partially reversed motor coordination deficits in Sacs-/- mice but did not affect litter-matched wild-type control mice. MitoQ administration led to a restoration of superoxide dismutase 2 (SOD2) in cerebellar Purkinje cell somata without altering Purkinje cell firing deficits. Purkinje cells in anterior vermis of Sacs-/- mice normally undergo cell death in ARSACS; however, Purkinje cells numbers were elevated after chronic MitoQ treatment. Furthermore, Purkinje cell innervation of target neurons in the cerebellar nuclei of Sacs-/- mice were also partially restored with MitoQ treatment. Our data suggest that MitoQ is a potential therapeutic treatment for ARSACS and that it improves motor coordination via increasing cerebellar Purkinje cell mitochondria function and reducing Purkinje cell death.
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Affiliation(s)
| | | | - Jeanette Hui
- Department of Biology, McGill University, Montreal, QC, Canada
| | - François Charron
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
| | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada.
| | - Alanna J Watt
- Department of Biology, McGill University, Montreal, QC, Canada.
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Maysinger D, Zhang I, Wu PY, Kagelmacher M, Luo HD, Kizhakkedathu JN, Dernedde J, Ballauff M, Haag R, Shobo A, Multhaup G, McKinney RA. Sulfated Hyperbranched and Linear Polyglycerols Modulate HMGB1 and Morphological Plasticity in Neural Cells. ACS Chem Neurosci 2023; 14:677-688. [PMID: 36717083 DOI: 10.1021/acschemneuro.2c00558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The objective of this study was to establish if polyglycerols with sulfate or sialic acid functional groups interact with high mobility group box 1 (HMGB1), and if so, which polyglycerol could prevent loss of morphological plasticity in excitatory neurons in the hippocampus. Considering that HMGB1 binds to heparan sulfate and that heparan sulfate has structural similarities with dendritic polyglycerol sulfates (dPGS), we performed the experiments to show if polyglycerols can mimic heparin functions by addressing the following questions: (1) do dendritic and linear polyglycerols interact with the alarmin molecule HMGB1? (2) Does dPGS interaction with HMGB1 influence the redox status of HMGB1? (3) Can dPGS prevent the loss of dendritic spines in organotypic cultures challenged with lipopolysaccharide (LPS)? LPS plays a critical role in infections with Gram-negative bacteria and is commonly used to test candidate therapeutic agents for inflammation and endotoxemia. Pathologically high LPS concentrations and other stressful stimuli cause HMGB1 release and post-translational modifications. We hypothesized that (i) electrostatic interactions of hyperbranched and linear polysulfated polyglycerols with HMGB1 will likely involve sites similar to those of heparan sulfate. (ii) dPGS can normalize HMGB1 compartmentalization in microglia exposed to LPS and prevent dendritic spine loss in the excitatory hippocampal neurons. We performed immunocytochemistry and biochemical analyses combined with confocal microscopy to determine cellular and extracellular locations of HMGB1 and morphological plasticity. Our results suggest that dPGS interacts with HMGB1 similarly to heparan sulfate. Hyperbranched dPGS and linear sulfated polymers prevent dendritic spine loss in hippocampal excitatory neurons. MS/MS analyses reveal that dPGS-HMGB1 interactions result in fully oxidized HMGB1 at critical cysteine residues (Cys23, Cys45, and Cys106). Triply oxidized HMGB1 leads to the loss of its pro-inflammatory action and could participate in dPGS-mediated spine loss prevention. LPG-Sia exposure to HMGB1 results in the oxidation of Cys23 and Cys106 but does not normalize spine density.
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Affiliation(s)
- Dusica Maysinger
- Department of Pharmacology and Therapeutics, McGill University, MontrealH3G 1Y6, Canada
| | - Issan Zhang
- Department of Pharmacology and Therapeutics, McGill University, MontrealH3G 1Y6, Canada
| | - Pei You Wu
- Department of Pharmacology and Therapeutics, McGill University, MontrealH3G 1Y6, Canada
| | - Marten Kagelmacher
- Institut für Chemie und Biochemie, Freie Universität Berlin, Berlin14195, Germany
| | - Haiming Daniel Luo
- Centre for Blood Research, Department of Pathology and Laboratory Medicine, Life Science Institute, Department of Chemistry, School of Biomedical Engineering, University of British Columbia, VancouverV6T 1Z3, Canada
| | - Jayachandran N Kizhakkedathu
- Centre for Blood Research, Department of Pathology and Laboratory Medicine, Life Science Institute, Department of Chemistry, School of Biomedical Engineering, University of British Columbia, VancouverV6T 1Z3, Canada
| | - Jens Dernedde
- Institute of Laboratory Medicine, Clinical Chemistry, and Pathobiochemistry, Charité-Universitätsmedizin Berlin, Berlin13353, Germany
| | - Matthias Ballauff
- Institut für Chemie und Biochemie, Freie Universität Berlin, Berlin14195, Germany
| | - Rainer Haag
- Institut für Chemie und Biochemie, Freie Universität Berlin, Berlin14195, Germany
| | - Adeola Shobo
- Department of Pharmacology and Therapeutics, McGill University, MontrealH3G 1Y6, Canada
| | - Gerhard Multhaup
- Department of Pharmacology and Therapeutics, McGill University, MontrealH3G 1Y6, Canada
| | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University, MontrealH3G 1Y6, Canada
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7
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Karmon G, Sragovich S, Hacohen-Kleiman G, Ben-Horin-Hazak I, Kasparek P, Schuster B, Sedlacek R, Pasmanik-Chor M, Theotokis P, Touloumi O, Zoidou S, Huang L, Wu PY, Shi R, Kapitansky O, Lobyntseva A, Giladi E, Shapira G, Shomron N, Bereswill S, Heimesaat MM, Grigoriadis N, McKinney RA, Rubinstein M, Gozes I. Novel ADNP Syndrome Mice Reveal Dramatic Sex-Specific Peripheral Gene Expression With Brain Synaptic and Tau Pathologies. Biol Psychiatry 2022; 92:81-95. [PMID: 34865853 DOI: 10.1016/j.biopsych.2021.09.018] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 08/19/2021] [Accepted: 09/17/2021] [Indexed: 01/18/2023]
Abstract
BACKGROUND ADNP is essential for embryonic development. As such, de novo ADNP mutations lead to an intractable autism/intellectual disability syndrome requiring investigation. METHODS Mimicking humans, CRISPR (clustered regularly interspaced short palindromic repeats)-Cas9 editing produced mice carrying heterozygous Adnp p.Tyr718∗ (Tyr), a paralog of the most common ADNP syndrome mutation. Phenotypic rescue was validated by treatment with the microtubule/autophagy-protective ADNP fragment NAPVSIPQ (NAP). RESULTS RNA sequencing of spleens, representing a peripheral biomarker source, revealed Tyr-specific sex differences (e.g., cell cycle), accentuated in females (with significant effects on antigen processing and cellular senescence) and corrected by NAP. Differentially expressed, NAP-correctable transcripts, including the autophagy and microbiome resilience-linked FOXO3, were also deregulated in human patient-derived ADNP-mutated lymphoblastoid cells. There were also Tyr sex-specific microbiota signatures. Phenotypically, Tyr mice, similar to patients with ADNP syndrome, exhibited delayed development coupled with sex-dependent gait defects. Speech acquisition delays paralleled sex-specific mouse syntax abnormalities. Anatomically, dendritic spine densities/morphologies were decreased with NAP amelioration. These findings were replicated in the Adnp+/- mouse, including Foxo3 deregulation, required for dendritic spine formation. Grooming duration and nociception threshold (autistic traits) were significantly affected only in males. Early-onset tauopathy was accentuated in males (hippocampus and visual cortex), mimicking humans, and was paralleled by impaired visual evoked potentials and correction by acute NAP treatment. CONCLUSIONS Tyr mice model ADNP syndrome pathology. The newly discovered ADNP/NAP target FOXO3 controls the autophagy initiator LC3 (microtubule-associated protein 1 light chain 3), with known ADNP binding to LC3 augmented by NAP, protecting against tauopathy. NAP amelioration attests to specificity, with potential for drug development targeting accessible biomarkers.
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Affiliation(s)
- Gidon Karmon
- Elton Laboratory for Molecular Neuroendocrinology, Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, Israel
| | - Shlomo Sragovich
- Elton Laboratory for Molecular Neuroendocrinology, Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, Israel
| | - Gal Hacohen-Kleiman
- Elton Laboratory for Molecular Neuroendocrinology, Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, Israel
| | - Inbar Ben-Horin-Hazak
- Elton Laboratory for Molecular Neuroendocrinology, Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, Israel
| | - Petr Kasparek
- Department of Transgenic Models of Diseases and Czech Centre for Phenogenomics, Institute of Molecular Genetics of the Czech Academy of Sciences, Vestec, Czech Republic
| | - Björn Schuster
- Department of Transgenic Models of Diseases and Czech Centre for Phenogenomics, Institute of Molecular Genetics of the Czech Academy of Sciences, Vestec, Czech Republic
| | - Radislav Sedlacek
- Department of Transgenic Models of Diseases and Czech Centre for Phenogenomics, Institute of Molecular Genetics of the Czech Academy of Sciences, Vestec, Czech Republic
| | - Metsada Pasmanik-Chor
- Bioinformatics Unit, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Paschalis Theotokis
- Department of Neurology, Laboratory of Experimental Neurology, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Olga Touloumi
- Department of Neurology, Laboratory of Experimental Neurology, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Sofia Zoidou
- Department of Neurology, Laboratory of Experimental Neurology, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Linxuan Huang
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Pei You Wu
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Roy Shi
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Oxana Kapitansky
- Elton Laboratory for Molecular Neuroendocrinology, Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, Israel
| | - Alexandra Lobyntseva
- Elton Laboratory for Molecular Neuroendocrinology, Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, Israel
| | - Eliezer Giladi
- Elton Laboratory for Molecular Neuroendocrinology, Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, Israel
| | - Guy Shapira
- Department of Cell and Developmental Biology and Edmond J. Safra Center for Bioinformatics, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Noam Shomron
- Department of Cell and Developmental Biology and Edmond J. Safra Center for Bioinformatics, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Stefan Bereswill
- Gastrointestinal Microbiology Research Group, Institute for Microbiology, Infectious Diseases and Immunology, Charité-University Medicine Berlin, Berlin, Germany
| | - Markus M Heimesaat
- Gastrointestinal Microbiology Research Group, Institute for Microbiology, Infectious Diseases and Immunology, Charité-University Medicine Berlin, Berlin, Germany
| | - Nikolaos Grigoriadis
- Department of Neurology, Laboratory of Experimental Neurology, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Moran Rubinstein
- Elton Laboratory for Molecular Neuroendocrinology, Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, Israel; Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Illana Gozes
- Elton Laboratory for Molecular Neuroendocrinology, Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, Israel.
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8
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Gao AYL, Lourdin-De Filippis E, Orlowski J, McKinney RA. Roles of Endomembrane Alkali Cation/Proton Exchangers in Synaptic Function and Neurodevelopmental Disorders. Front Physiol 2022; 13:892196. [PMID: 35547574 PMCID: PMC9081726 DOI: 10.3389/fphys.2022.892196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 03/30/2022] [Indexed: 12/25/2022] Open
Abstract
Endomembrane alkali cation (Na+, K+)/proton (H+) exchangers (eNHEs) are increasingly associated with neurological disorders. These eNHEs play integral roles in regulating the luminal pH, processing, and trafficking of cargo along the secretory (Golgi and post-Golgi vesicles) and endocytic (early, recycling, and late endosomes) pathways, essential regulatory processes vital for neuronal development and plasticity. Given the complex morphology and compartmentalization of multipolar neurons, the contribution of eNHEs in maintaining optimal pH homeostasis and cargo trafficking is especially significant during periods of structural and functional development and remodeling. While the importance of eNHEs has been demonstrated in a variety of non-neuronal cell types, their involvement in neuronal function is less well understood. In this review, we will discuss their emerging roles in excitatory synaptic function, particularly as it pertains to cellular learning and remodeling. We will also explore their connections to neurodevelopmental conditions, including intellectual disability, autism, and attention deficit hyperactivity disorders.
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Affiliation(s)
- Andy Y L Gao
- Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada.,Department of Pharmacology & Therapeutics, McGill University, Montreal, QC, Canada
| | | | - John Orlowski
- Department of Physiology, McGill University, Montreal, QC, Canada
| | - R Anne McKinney
- Department of Pharmacology & Therapeutics, McGill University, Montreal, QC, Canada
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9
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Thirouin ZS, Figueiredo M, Hleihil M, Gill R, Bosshard G, McKinney RA, Tyagarajan SK. Trophic factor BDNF inhibits GABAergic signaling by facilitating dendritic enrichment of SUMO E3 ligase PIAS3 and altering gephyrin scaffold. J Biol Chem 2022; 298:101840. [PMID: 35307349 PMCID: PMC9019257 DOI: 10.1016/j.jbc.2022.101840] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/03/2022] [Accepted: 03/04/2022] [Indexed: 11/18/2022] Open
Abstract
Posttranslational addition of a small ubiquitin-like modifier (SUMO) moiety (SUMOylation) has been implicated in pathologies such as brain ischemia, diabetic peripheral neuropathy, and neurodegeneration. However, nuclear enrichment of SUMO pathway proteins has made it difficult to ascertain how ion channels, proteins that are typically localized to and function at the plasma membrane, and mitochondria are SUMOylated. Here, we report that the trophic factor, brain-derived neurotrophic factor (BDNF) regulates SUMO proteins both spatially and temporally in neurons. We show that BDNF signaling via the receptor tropomyosin-related kinase B facilitates nuclear exodus of SUMO proteins and subsequent enrichment within dendrites. Of the various SUMO E3 ligases, we found that PIAS-3 dendrite enrichment in response to BDNF signaling specifically modulates subsequent ERK1/2 kinase pathway signaling. In addition, we found the PIAS-3 RING and Ser/Thr domains, albeit in opposing manners, functionally inhibit GABA-mediated inhibition. Finally, using oxygen–glucose deprivation as an in vitro model for ischemia, we show that BDNF–tropomyosin-related kinase B signaling negatively impairs clustering of the main scaffolding protein at GABAergic postsynapse, gephyrin, whereby reducing GABAergic neurotransmission postischemia. SUMOylation-defective gephyrin K148R/K724R mutant transgene expression reversed these ischemia-induced changes in gephyrin cluster density. Taken together, these data suggest that BDNF signaling facilitates the temporal relocation of nuclear-enriched SUMO proteins to dendrites to influence postsynaptic protein SUMOylation.
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Affiliation(s)
- Zahra S Thirouin
- Institute of Pharmacology and Toxicology, University of Zürich, Zürich, Switzerland
| | - Marta Figueiredo
- Institute of Pharmacology and Toxicology, University of Zürich, Zürich, Switzerland
| | - Mohammad Hleihil
- Institute of Pharmacology and Toxicology, University of Zürich, Zürich, Switzerland
| | - Raminder Gill
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - Giovanna Bosshard
- Institute of Pharmacology and Toxicology, University of Zürich, Zürich, Switzerland
| | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - Shiva K Tyagarajan
- Institute of Pharmacology and Toxicology, University of Zürich, Zürich, Switzerland.
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10
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Toscano Márquez B, Cook AA, Rice M, Smileski A, Vieira-Lomasney K, Charron F, McKinney RA, Watt AJ. Molecular Identity and Location Influence Purkinje Cell Vulnerability in Autosomal-Recessive Spastic Ataxia of Charlevoix-Saguenay Mice. Front Cell Neurosci 2022; 15:707857. [PMID: 34970120 PMCID: PMC8712330 DOI: 10.3389/fncel.2021.707857] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 11/03/2021] [Indexed: 11/13/2022] Open
Abstract
Patterned cell death is a common feature of many neurodegenerative diseases. In patients with autosomal-recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) and mouse models of ARSACS, it has been observed that Purkinje cells in anterior cerebellar vermis are vulnerable to degeneration while those in posterior vermis are resilient. Purkinje cells are known to express certain molecules in a highly stereotyped, patterned manner across the cerebellum. One patterned molecule is zebrin, which is expressed in distinctive stripes across the cerebellar cortex. The different zones delineated by the expression pattern of zebrin and other patterned molecules have been implicated in the patterning of Purkinje cell death, raising the question of whether they contribute to cell death in ARSACS. We found that zebrin patterning appears normal prior to disease onset in Sacs–/– mice, suggesting that zebrin-positive and -negative Purkinje cell zones develop normally. We next observed that zebrin-negative Purkinje cells in anterior lobule III were preferentially susceptible to cell death, while anterior zebrin-positive cells and posterior zebrin-negative and -positive cells remained resilient even at late disease stages. The patterning of Purkinje cell innervation to the target neurons in the cerebellar nuclei (CN) showed a similar pattern of loss: neurons in the anterior CN, where inputs are predominantly zebrin-negative, displayed a loss of Purkinje cell innervation. In contrast, neurons in the posterior CN, which is innervated by both zebrin-negative and -positive puncta, had normal innervation. These results suggest that the location and the molecular identity of Purkinje cells determine their susceptibility to cell death in ARSACS.
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Affiliation(s)
| | - Anna A Cook
- Department of Biology, McGill University, Montreal, QC, Canada
| | - Max Rice
- Department of Biology, McGill University, Montreal, QC, Canada
| | - Alexia Smileski
- Department of Biology, McGill University, Montreal, QC, Canada
| | | | - François Charron
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
| | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
| | - Alanna J Watt
- Department of Biology, McGill University, Montreal, QC, Canada
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11
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Gruber R, Scholes S, Bertone A, McKinney RA, Orlowski J, Wise MS. Sleep and daytime behavior in individuals with Christianson Syndrome. Sleep Med 2021; 89:55-59. [PMID: 34883399 DOI: 10.1016/j.sleep.2021.11.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 11/09/2021] [Accepted: 11/13/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND The objectives of this study were to: 1) characterize the sleep behaviors and symptoms of individuals with Christianson Syndrome (CS) by means of validated questionnaires; and 2) determine their associations with daytime emotional and behavioral symptoms in this population. METHODS Participants included 16 boys genetically diagnosed with CS, between 2.5 and 40 years of age (M = 14.5 ± 8.08). Parents completed questionnaires regarding the sleep, daytime behavior, and health of their child. RESULTS Of the participants, 31% did not obtain the recommended amount of sleep for their age, 43% experienced a prolonged sleep latency, and 88% had a clinical or sub-clinical score for at least one subscale of the Sleep Disturbance Scale for Children (SDSC). Specific problems detected included insomnia, sleep-wake transition disorders, periodic limb movements in sleep, and sleep related breathing disorders. About half of the participants manifested emotional and behavioral problems at clinical levels. Higher levels of sleep disturbances were associated with higher levels of behavioral and emotional daytime symptoms. CONCLUSIONS Sleep problems are common in individuals with CS and are associated with daytime behavioral and emotional symptoms.
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Affiliation(s)
- Reut Gruber
- Attention, Behavior and Sleep Laboratory, Douglas Hospital Research Centre, Montreal, Quebec, Canada; Department of Psychiatry, McGill University, Montréal, Québec, Canada.
| | - Samantha Scholes
- Attention, Behavior and Sleep Laboratory, Douglas Hospital Research Centre, Montreal, Quebec, Canada; Perceptual Neuroscience Lab (PNLab) for Autism, Development Department of Educational and Counselling Psychology, McGill University, Montréal, Québec, Canada
| | - Armando Bertone
- Perceptual Neuroscience Lab (PNLab) for Autism, Development Department of Educational and Counselling Psychology, McGill University, Montréal, Québec, Canada
| | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada
| | - John Orlowski
- Department of Physiology, McGill University, Montreal, Québec, Canada
| | - Merrill S Wise
- Mid-South Pulmonary and Sleep Specialists, Memphis, TN, USA
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12
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Ilie A, Boucher A, Park J, Berghuis AM, McKinney RA, Orlowski J. Assorted dysfunctions of endosomal alkali cation/proton exchanger SLC9A6 variants linked to Christianson syndrome. J Biol Chem 2020; 295:7075-7095. [PMID: 32277048 PMCID: PMC7242699 DOI: 10.1074/jbc.ra120.012614] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 04/07/2020] [Indexed: 12/15/2022] Open
Abstract
Genetic screening has identified numerous variants of the endosomal solute carrier family 9 member A6 (SLC9A6)/(Na+,K+)/H+ exchanger 6 (NHE6) gene that cause Christianson syndrome, a debilitating X-linked developmental disorder associated with a range of neurological, somatic, and behavioral symptoms. Many of these variants cause complete loss of NHE6 expression, but how subtler missense substitutions or nonsense mutations that partially truncate its C-terminal cytoplasmic regulatory domain impair NHE6 activity and endosomal function are poorly understood. Here, we describe the molecular and cellular consequences of six unique mutations located in the N-terminal cytoplasmic segment (A9S), the membrane ion translocation domain (L188P and G383D), and the C-terminal regulatory domain (E547*, R568Q, and W570*) of human NHE6 that purportedly cause disease. Using a heterologous NHE6-deficient cell expression system, we show that the biochemical, catalytic, and cellular properties of the A9S and R568Q variants were largely indistinguishable from those of the WT transporter, which obscured their disease significance. By contrast, the L188P, G383D, E547*, and W570* mutants exhibited variable deficiencies in biosynthetic post-translational maturation, membrane sorting, pH homeostasis in recycling endosomes, and cargo trafficking, and they also triggered apoptosis. These findings broaden our understanding of the molecular dysfunctions of distinct NHE6 variants associated with Christianson syndrome.
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Affiliation(s)
- Alina Ilie
- Department of Physiology, McGill University, Montreal, Quebec H3G 0B1, Canada
| | - Annie Boucher
- Department of Physiology, McGill University, Montreal, Quebec H3G 0B1, Canada
| | - Jaeok Park
- Department of Biochemistry, McGill University, Montreal, Quebec H3G 0B1, Canada
| | | | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec H3G 0B1, Canada
| | - John Orlowski
- Department of Physiology, McGill University, Montreal, Quebec H3G 0B1, Canada
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13
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Abstract
Exposing chicks to one hour of light during the night disrupts the release of a hormone that is needed by cells in the developing brain to survive.
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Affiliation(s)
| | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - Alanna J Watt
- Department of Biology, McGill University, Montreal, Canada
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14
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Josephy-Hernandez S, Pirvulescu I, Maira M, Aboulkassim T, Wong TP, McKinney RA, Saragovi HU. Pharmacological interrogation of TrkA-mediated mechanisms in hippocampal-dependent memory consolidation. PLoS One 2019; 14:e0218036. [PMID: 31233568 PMCID: PMC6590805 DOI: 10.1371/journal.pone.0218036] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 05/23/2019] [Indexed: 11/18/2022] Open
Abstract
In the brain, the TrkA receptor for Nerve Growth Factor (NGF) is expressed primarily in the cholinergic system. TrkA/NGF support neuronal health and function, and deficiencies in this axis are associated with progressive cholinergic neuron atrophy and death, and with cognitive deficit in disorders such as Down's syndrome and Alzheimer's disease. These observations led to the hypothesis that TrkA agonists may rescue atrophic cholinergic neurons and benefit cognition. Indeed, a small molecule TrkA partial agonist called D3 normalized TrkA signals and improved memory in cognitive impairment models of ageing and an APP mouse model of Alzheimer's disease. Paradoxically, in young healthy mice chronic delivery of D3 caused impaired memory without impairing learning, a form of anterograde amnesia. Here, we use this as a model to study the mechanisms of impaired memory. In young healthy mice acute or chronic treatment with D3 induces hyperactivation of TrkA-mediated signals in hippocampus, and causes a deficit in hippocampal-dependent memory consolidation proximal to drug exposure, without affecting learning or memory retrieval. The impairment after acute drug exposure is reversible. The impairment after long-term drug exposure is irreversible, likely due to a decrease in hippocampal CA1 neuron basal arborization. These findings support the notion of a homeostatic role for TrkA in memory, and demonstrate the differential outcomes of TrkA (hyper)activation in healthy versus disease states.
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Affiliation(s)
- Sylvia Josephy-Hernandez
- Lady Davis Institute-Jewish General Hospital, Montreal, Quebec, Canada
- Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada
| | - Iulia Pirvulescu
- Lady Davis Institute-Jewish General Hospital, Montreal, Quebec, Canada
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Mario Maira
- Lady Davis Institute-Jewish General Hospital, Montreal, Quebec, Canada
| | - Tahar Aboulkassim
- Lady Davis Institute-Jewish General Hospital, Montreal, Quebec, Canada
| | - Tak Pan Wong
- Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada
- Douglas Mental Health University Institute, Montreal, Quebec, Canada
- Department of Psychiatry, McGill University, Montreal, Quebec, Canada
| | - R. Anne McKinney
- Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - H. Uri Saragovi
- Lady Davis Institute-Jewish General Hospital, Montreal, Quebec, Canada
- Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
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15
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Larivière R, Sgarioto N, Márquez BT, Gaudet R, Choquet K, McKinney RA, Watt AJ, Brais B. Sacs R272C missense homozygous mice develop an ataxia phenotype. Mol Brain 2019; 12:19. [PMID: 30866998 PMCID: PMC6416858 DOI: 10.1186/s13041-019-0438-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 02/25/2019] [Indexed: 12/29/2022] Open
Abstract
Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS [MIM 270550]) is an early-onset neurodegenerative disorder caused by mutations in the SACS gene. Over 200 SACS mutations have been identified. Most mutations lead to a complete loss of a sacsin, a large 520 kD protein, although some missense mutations are associated with low levels of sacsin expression. We previously showed that Sacs knock-out mice demonstrate early-onset ataxic phenotype with neurofilament bundling in many neuronal populations. To determine if the preservation of some mutated sacsin protein resulted in the same cellular and behavioral alterations, we generated mice expressing an R272C missense mutation, a homozygote mutation found in some affected patients. Though SacsR272C mice express 21% of wild type brain sacsin and sacsin is found in many neurons, they display similar abnormalities to Sacs knock-out mice, including the development of an ataxic phenotype, reduced Purkinje cell firing rates, and somatodendritic neurofilament bundles in Purkinje cells and other neurons. Together our results support that Sacs missense mutation largely lead to loss of sacsin function.
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Affiliation(s)
- Roxanne Larivière
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Room 622, 3801, University Street, Montreal, Québec, H3A 2B4, Canada
| | - Nicolas Sgarioto
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Room 622, 3801, University Street, Montreal, Québec, H3A 2B4, Canada
| | | | - Rébecca Gaudet
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Room 622, 3801, University Street, Montreal, Québec, H3A 2B4, Canada
| | - Karine Choquet
- Department of Human Genetics, Montreal Neurological Institute, McGill University, Montreal, Qc, Canada
| | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Qc, Canada
| | - Alanna J Watt
- Department of Biology, McGill University, Montreal, Qc, Canada
| | - Bernard Brais
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Room 622, 3801, University Street, Montreal, Québec, H3A 2B4, Canada.
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16
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Ji J, Moquin A, Bertorelle F, KY Chang P, Antoine R, Luo J, McKinney RA, Maysinger D. Organotypic and primary neural cultures as models to assess effects of different gold nanostructures on glia and neurons. Nanotoxicology 2019; 13:285-304. [DOI: 10.1080/17435390.2018.1543468] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Jeff Ji
- Department of Pharmacology & Therapeutics, McGill University, Montreal, Canada
| | - Alexandre Moquin
- Department of Pharmacology & Therapeutics, McGill University, Montreal, Canada
| | - Franck Bertorelle
- CNRS, Institut Lumière Matière, Université Lyon Université Claude Bernard Lyon 1, Lyon, France
| | - Philip KY Chang
- Department of Pharmacology & Therapeutics, McGill University, Montreal, Canada
| | - Rodolphe Antoine
- CNRS, Institut Lumière Matière, Université Lyon Université Claude Bernard Lyon 1, Lyon, France
| | - Julia Luo
- Department of Pharmacology & Therapeutics, McGill University, Montreal, Canada
| | - R. Anne McKinney
- Department of Pharmacology & Therapeutics, McGill University, Montreal, Canada
| | - Dusica Maysinger
- Department of Pharmacology & Therapeutics, McGill University, Montreal, Canada
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17
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Glasgow SD, Labrecque S, Beamish IV, Aufmkolk S, Gibon J, Han D, Harris SN, Dufresne P, Wiseman PW, McKinney RA, Séguéla P, De Koninck P, Ruthazer ES, Kennedy TE. Activity-Dependent Netrin-1 Secretion Drives Synaptic Insertion of GluA1-Containing AMPA Receptors in the Hippocampus. Cell Rep 2018; 25:168-182.e6. [DOI: 10.1016/j.celrep.2018.09.028] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 05/30/2018] [Accepted: 09/06/2018] [Indexed: 11/28/2022] Open
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18
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Hacohen-Kleiman G, Sragovich S, Karmon G, Gao AYL, Grigg I, Pasmanik-Chor M, Le A, Korenková V, McKinney RA, Gozes I. Activity-dependent neuroprotective protein deficiency models synaptic and developmental phenotypes of autism-like syndrome. J Clin Invest 2018; 128:4956-4969. [PMID: 30106381 DOI: 10.1172/jci98199] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 07/31/2018] [Indexed: 12/11/2022] Open
Abstract
Previous findings showed that in mice, complete knockout of activity-dependent neuroprotective protein (ADNP) abolishes brain formation, while haploinsufficiency (Adnp+/-) causes cognitive impairments. We hypothesized that mutations in ADNP lead to a developmental/autistic syndrome in children. Indeed, recent phenotypic characterization of children harboring ADNP mutations (ADNP syndrome children) revealed global developmental delays and intellectual disabilities, including speech and motor dysfunctions. Mechanistically, ADNP includes a SIP motif embedded in the ADNP-derived snippet drug candidate NAP (NAPVSIPQ, also known as CP201), which binds to microtubule end-binding protein 3, essential for dendritic spine formation. Here, we established a unique neuronal membrane-tagged, GFP-expressing Adnp+/- mouse line allowing in vivo synaptic pathology quantification. We discovered that Adnp deficiency reduced dendritic spine density and altered synaptic gene expression, both of which were partly ameliorated by NAP treatment. Adnp+/-mice further exhibited global developmental delays, vocalization impediments, gait and motor dysfunctions, and social and object memory impairments, all of which were partially reversed by daily NAP administration (systemic/nasal). In conclusion, we have connected ADNP-related synaptic pathology to developmental and behavioral outcomes, establishing NAP in vivo target engagement and identifying potential biomarkers. Together, these studies pave a path toward the clinical development of NAP (CP201) for the treatment of ADNP syndrome.
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Affiliation(s)
- Gal Hacohen-Kleiman
- The Lily and Avraham Gildor Chair for the Investigation of Growth Factors; The Elton Laboratory for Neuroendocrinology; Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, Israel
| | - Shlomo Sragovich
- The Lily and Avraham Gildor Chair for the Investigation of Growth Factors; The Elton Laboratory for Neuroendocrinology; Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, Israel
| | - Gidon Karmon
- The Lily and Avraham Gildor Chair for the Investigation of Growth Factors; The Elton Laboratory for Neuroendocrinology; Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, Israel
| | - Andy Y L Gao
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Iris Grigg
- The Lily and Avraham Gildor Chair for the Investigation of Growth Factors; The Elton Laboratory for Neuroendocrinology; Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, Israel
| | - Metsada Pasmanik-Chor
- Bioinformatics Unit, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Albert Le
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | | | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Illana Gozes
- The Lily and Avraham Gildor Chair for the Investigation of Growth Factors; The Elton Laboratory for Neuroendocrinology; Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, Israel
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19
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Ady V, Toscano-Márquez B, Nath M, Chang PK, Hui J, Cook A, Charron F, Larivière R, Brais B, McKinney RA, Watt AJ. Altered synaptic and firing properties of cerebellar Purkinje cells in a mouse model of ARSACS. J Physiol 2018; 596:4253-4267. [PMID: 29928778 DOI: 10.1113/jp275902] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 06/19/2018] [Indexed: 12/20/2022] Open
Abstract
KEY POINTS Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is an early-onset neurodegenerative human disease characterized in part by ataxia and Purkinje cell loss in anterior cerebellar lobules. A knock-out mouse model has been developed that recapitulates several features of ARSACS. Using this ARSACS mouse model, we report changes in synaptic input and intrinsic firing in cerebellar Purkinje cells, as well as in their synaptic output in the deep cerebellar nuclei. Changes in firing are observed in anterior lobules that later exhibit Purkinje cell death, but not in posterior lobules that do not. Our results show that both synaptic and intrinsic alterations in Purkinje cell properties likely contribute to disease manifestation in ARSACS; these findings resemble pathophysiological changes reported in several other ataxias. ABSTRACT Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is an early-onset neurodegenerative disease that includes a pronounced and progressive cerebellar dysfunction. ARSACS is caused by an autosomal recessive loss-of-function mutation in the Sacs gene that encodes the protein sacsin. To better understand the cerebellar pathophysiology in ARSACS, we studied synaptic and firing properties of Purkinje cells from a mouse model of ARSACS, Sacs-/- mice. We found that excitatory synaptic drive was reduced onto Sacs-/- Purkinje cells, and that Purkinje cell firing rate, but not regularity, was reduced at postnatal day (P)40, an age when ataxia symptoms were first reported. Firing rate deficits were limited to anterior lobules that later display Purkinje cell death, and were not observed in posterior lobules where Purkinje cells are not lost. Mild firing deficits were observed as early as P20, prior to the manifestation of motor deficits, suggesting that a critical level of cerebellar dysfunction is required for motor coordination to emerge. Finally, we observed a reduction in Purkinje cell innervation onto target neurons in the deep cerebellar nuclei (DCN) in Sacs-/- mice. Together, these findings suggest that multiple alterations in the cerebellar circuit including Purkinje cell input and output contribute to cerebellar-related disease onset in ARSACS.
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Affiliation(s)
- Visou Ady
- Department of Biology, McGill University, Montréal, Canada
| | | | - Moushumi Nath
- Department of Biology, McGill University, Montréal, Canada
| | - Philip K Chang
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Canada
| | - Jeanette Hui
- Department of Biology, McGill University, Montréal, Canada
| | - Anna Cook
- Department of Biology, McGill University, Montréal, Canada
| | - François Charron
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Canada
| | - Roxanne Larivière
- Department of Neurology and Neurosurgery, Montréal Neurological Institute, McGill University, Montréal, Canada
| | - Bernard Brais
- Department of Neurology and Neurosurgery, Montréal Neurological Institute, McGill University, Montréal, Canada
| | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Canada
| | - Alanna J Watt
- Department of Biology, McGill University, Montréal, Canada
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20
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Maysinger D, Ji J, Moquin A, Hossain S, Hancock MA, Zhang I, Chang PK, Rigby M, Anthonisen M, Grütter P, Breitner J, McKinney RA, Reimann S, Haag R, Multhaup G. Dendritic Polyglycerol Sulfates in the Prevention of Synaptic Loss and Mechanism of Action on Glia. ACS Chem Neurosci 2018; 9:260-271. [PMID: 29078046 DOI: 10.1021/acschemneuro.7b00301] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Dendritic polyglycerols (dPG), particularly dendritic polyglycerol sulfates (dPGS), have been intensively studied due to their intrinsic anti-inflammatory activity. As related to brain pathologies involving neuroinflammation, the current study examined if dPG and dPGS can (i) regulate neuroglial activation, and (ii) normalize the morphology and function of excitatory postsynaptic dendritic spines adversely affected by the neurotoxic 42 amino acid amyloid-β (Aβ42) peptide of Alzheimer disease (AD). The exact role of neuroglia, such as microglia and astrocytes, remains controversial especially their positive and negative impact on inflammatory processes in AD. To test dPGS effectiveness in AD models we used primary neuroglia and organotypic hippocampal slice cultures exposed to Aβ42 peptide. Overall, our data indicate that dPGS is taken up by both microglia and astrocytes in a concentration- and time-dependent manner. The mechanism of action of dPGS involves binding to Aβ42, i.e., a direct interaction between dPGS and Aβ42 species interfered with Aβ fibril formation and reduced the production of the neuroinflammagen lipocalin-2 (LCN2) mainly in astrocytes. Moreover, dPGS normalized the impairment of neuroglia and prevented the loss of dendritic spines at excitatory synapses in the hippocampus. In summary, dPGS has desirable therapeutic properties that may help reduce amyloid-induced neuroinflammation and neurotoxicity in AD.
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Affiliation(s)
- Dusica Maysinger
- Department
of Pharmacology and Therapeutics, McGill University, Montreal, Canada H3G 1Y6
| | - Jeff Ji
- Department
of Pharmacology and Therapeutics, McGill University, Montreal, Canada H3G 1Y6
| | - Alexandre Moquin
- Department
of Pharmacology and Therapeutics, McGill University, Montreal, Canada H3G 1Y6
| | - Shireen Hossain
- Department
of Pharmacology and Therapeutics, McGill University, Montreal, Canada H3G 1Y6
| | - Mark A. Hancock
- Department
of Pharmacology and Therapeutics, McGill University, Montreal, Canada H3G 1Y6
| | - Issan Zhang
- Department
of Pharmacology and Therapeutics, McGill University, Montreal, Canada H3G 1Y6
| | - Philip K.Y. Chang
- Department
of Pharmacology and Therapeutics, McGill University, Montreal, Canada H3G 1Y6
| | - Matthew Rigby
- Department
of Physics, McGill University, Montreal, Canada H3A 2T8
| | | | - Peter Grütter
- Department
of Physics, McGill University, Montreal, Canada H3A 2T8
| | - John Breitner
- Douglas
Hospital Research Centre, McGill University, Montreal, Canada H4H 1R3
| | - R. Anne McKinney
- Department
of Pharmacology and Therapeutics, McGill University, Montreal, Canada H3G 1Y6
| | - Sabine Reimann
- Institut
für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - Rainer Haag
- Institut
für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - Gerhard Multhaup
- Department
of Pharmacology and Therapeutics, McGill University, Montreal, Canada H3G 1Y6
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Ilie A, Gao AYL, Reid J, Boucher A, McEwan C, Barrière H, Lukacs GL, McKinney RA, Orlowski J. A Christianson syndrome-linked deletion mutation (∆(287)ES(288)) in SLC9A6 disrupts recycling endosomal function and elicits neurodegeneration and cell death. Mol Neurodegener 2016; 11:63. [PMID: 27590723 PMCID: PMC5010692 DOI: 10.1186/s13024-016-0129-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 08/27/2016] [Indexed: 01/19/2023] Open
Abstract
Background Christianson Syndrome, a recently identified X-linked neurodevelopmental disorder, is caused by mutations in the human gene SLC9A6 encoding the recycling endosomal alkali cation/proton exchanger NHE6. The patients have pronounced limitations in cognitive ability, motor skills and adaptive behaviour. However, the mechanistic basis for this disorder is poorly understood as few of the more than 20 mutations identified thus far have been studied in detail. Methods Here, we examined the molecular and cellular consequences of a 6 base-pair deletion of amino acids Glu287 and Ser288 (∆ES) in the predicted seventh transmembrane helix of human NHE6 expressed in established cell lines (CHO/AP-1, HeLa and neuroblastoma SH-SY5Y) and primary cultures of mouse hippocampal neurons by measuring levels of protein expression, stability, membrane trafficking, endosomal function and cell viability. Results In the cell lines, immunoblot analyses showed that the nascent mutant protein was properly synthesized and assembled as a homodimer, but its oligosaccharide maturation and half-life were markedly reduced compared to wild-type (WT) and correlated with enhanced ubiquitination leading to both proteasomal and lysosomal degradation. Despite this instability, a measurable fraction of the transporter was correctly sorted to the plasma membrane. However, the rates of clathrin-mediated endocytosis of the ∆ES mutant as well as uptake of companion vesicular cargo, such as the ligand-bound transferrin receptor, were significantly reduced and correlated with excessive endosomal acidification. Notably, ectopic expression of ∆ES but not WT induced apoptosis when examined in AP-1 cells. Similarly, in transfected primary cultures of mouse hippocampal neurons, membrane trafficking of the ∆ES mutant was impaired and elicited marked reductions in total dendritic length, area and arborization, and triggered apoptotic cell death. Conclusions These results suggest that loss-of-function mutations in NHE6 disrupt recycling endosomal function and trafficking of cargo which ultimately leads to neuronal degeneration and cell death in Christianson Syndrome. Electronic supplementary material The online version of this article (doi:10.1186/s13024-016-0129-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alina Ilie
- Department of Physiology, McGill University, Bellini Life Sciences Bldg., Rm, 166, 3649 Promenade Sir-William-Osler, Montreal, QC, H3G 0B1, Canada
| | - Andy Y L Gao
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - Jonathan Reid
- Department of Physiology, McGill University, Bellini Life Sciences Bldg., Rm, 166, 3649 Promenade Sir-William-Osler, Montreal, QC, H3G 0B1, Canada
| | - Annie Boucher
- Department of Physiology, McGill University, Bellini Life Sciences Bldg., Rm, 166, 3649 Promenade Sir-William-Osler, Montreal, QC, H3G 0B1, Canada
| | - Cassandra McEwan
- Department of Physiology, McGill University, Bellini Life Sciences Bldg., Rm, 166, 3649 Promenade Sir-William-Osler, Montreal, QC, H3G 0B1, Canada
| | - Hervé Barrière
- Department of Physiology, McGill University, Bellini Life Sciences Bldg., Rm, 166, 3649 Promenade Sir-William-Osler, Montreal, QC, H3G 0B1, Canada
| | - Gergely L Lukacs
- Department of Physiology, McGill University, Bellini Life Sciences Bldg., Rm, 166, 3649 Promenade Sir-William-Osler, Montreal, QC, H3G 0B1, Canada
| | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - John Orlowski
- Department of Physiology, McGill University, Bellini Life Sciences Bldg., Rm, 166, 3649 Promenade Sir-William-Osler, Montreal, QC, H3G 0B1, Canada.
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22
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Verbich D, Becker D, Vlachos A, Mundel P, Deller T, McKinney RA. Rewiring neuronal microcircuits of the brain via spine head protrusions--a role for synaptopodin and intracellular calcium stores. Acta Neuropathol Commun 2016; 4:38. [PMID: 27102112 PMCID: PMC4840984 DOI: 10.1186/s40478-016-0311-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 04/09/2016] [Indexed: 11/26/2022] Open
Abstract
Neurological diseases associated with neuronal death are also accompanied by axonal denervation of connected brain regions. In these areas, denervation leads to a decrease in afferent drive, which may in turn trigger active central nervous system (CNS) circuitry rearrangement. This rewiring process is important therapeutically, since it can partially recover functions and can be further enhanced using modern rehabilitation strategies. Nevertheless, the cellular mechanisms of brain rewiring are not fully understood. We recently reported a mechanism by which neurons remodel their local connectivity under conditions of network-perturbance: hippocampal pyramidal cells can extend spine head protrusions (SHPs), which reach out toward neighboring terminals and form new synapses. Since this form of activity-dependent rewiring is observed only on some spines, we investigated the required conditions. We speculated, that the actin-associated protein synaptopodin, which is involved in several synaptic plasticity mechanisms, could play a role in the formation and/or stabilization of SHPs. Using hippocampal slice cultures, we found that ~70 % of spines with protrusions in CA1 pyramidal neurons contained synaptopodin. Analysis of synaptopodin-deficient neurons revealed that synaptopodin is required for the stability but not the formation of SHPs. The effects of synaptopodin could be linked to its role in Ca2+ homeostasis, since spines with protrusions often contained ryanodine receptors and synaptopodin. Furthermore, disrupting Ca2+ signaling shortened protrusion lifetime. By transgenically reintroducing synaptopodin on a synaptopodin-deficient background, SHP stability could be rescued. Overall, we show that synaptopodin increases the stability of SHPs, and could potentially modulate the rewiring of microcircuitries by making synaptic reorganization more efficient.
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Maysinger D, Gröger D, Lake A, Licha K, Weinhart M, Chang PKY, Mulvey R, Haag R, McKinney RA. Dendritic Polyglycerol Sulfate Inhibits Microglial Activation and Reduces Hippocampal CA1 Dendritic Spine Morphology Deficits. Biomacromolecules 2015. [PMID: 26218295 DOI: 10.1021/acs.biomac.5b00999] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hyperactivity of microglia and loss of functional circuitry is a common feature of many neurological disorders including those induced or exacerbated by inflammation. Herein, we investigate the response of microglia and changes in hippocampal dendritic postsynaptic spines by dendritic polyglycerol sulfate (dPGS) treatment. Mouse microglia and organotypic hippocampal slices were exposed to dPGS and an inflammogen (lipopolysaccharides). Measurements of intracellular fluorescence and confocal microscopic analyses revealed that dPGS is avidly internalized by microglia but not CA1 pyramidal neurons. Concentration and time-dependent response studies consistently showed no obvious toxicity of dPGS. The adverse effects induced by proinflammogen LPS exposure were reduced and dendritic spine morphology was normalized with the addition of dPGS. This was accompanied by a significant reduction in nitrite and proinflammatory cytokines (TNF-α and IL-6) from hyperactive microglia suggesting normalized circuitry function with dPGS treatment. Collectively, these results suggest that dPGS acts anti-inflammatory, inhibits inflammation-induced degenerative changes in microglia phenotype and rescues dendritic spine morphology.
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Affiliation(s)
- Dusica Maysinger
- Department of Pharmacology and Therapeutics, McGill University , Montreal, QC Canada
| | - Dominic Gröger
- Institute of Chemistry and Biochemistry, Freie Universität Berlin , Takustr. 3, 14195 Berlin, Germany
| | - Andrew Lake
- Department of Pharmacology and Therapeutics, McGill University , Montreal, QC Canada
| | - Kai Licha
- Mivenion GmbH, Robert-Koch-Platz 4, 10115 Berlin, Germany
| | - Marie Weinhart
- Institute of Chemistry and Biochemistry, Freie Universität Berlin , Takustr. 3, 14195 Berlin, Germany
| | - Philip K-Y Chang
- Department of Pharmacology and Therapeutics, McGill University , Montreal, QC Canada
| | - Rose Mulvey
- Department of Pharmacology and Therapeutics, McGill University , Montreal, QC Canada.,Faculty of Medicine, Imperial College , London, United Kingdom
| | - Rainer Haag
- Institute of Chemistry and Biochemistry, Freie Universität Berlin , Takustr. 3, 14195 Berlin, Germany
| | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University , Montreal, QC Canada
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Morquette B, Morquette P, Agostinone J, Feinstein E, McKinney RA, Kolta A, Di Polo A. REDD2-mediated inhibition of mTOR promotes dendrite retraction induced by axonal injury. Cell Death Differ 2014; 22:612-25. [PMID: 25257176 PMCID: PMC4572858 DOI: 10.1038/cdd.2014.149] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 08/07/2014] [Accepted: 08/18/2014] [Indexed: 12/30/2022] Open
Abstract
Dendritic defects occur in neurodegenerative diseases accompanied by axonopathy, yet the mechanisms that regulate these pathologic changes are poorly understood. Using Thy1-YFPH mice subjected to optic nerve axotomy, we demonstrate early retraction of retinal ganglion cell (RGC) dendrites and selective loss of mammalian target of rapamycin (mTOR) activity, which precede soma loss. Axonal injury triggered rapid upregulation of the stress-induced protein REDD2 (regulated in development and DNA damage response 2), a potent inhibitor of mTOR. Short interfering RNA-mediated REDD2 knockdown restored mTOR activity and rescued dendritic length, area and branch complexity in a rapamycin-dependent manner. Whole-cell recordings demonstrated that REDD2 depletion leading to mTOR activation in RGCs restored their light response properties. Lastly, we show that REDD2-dependent mTOR activity extended RGC survival following axonal damage. These results indicate that injury-induced stress leads to REDD2 upregulation, mTOR inhibition and dendrite pathology causing neuronal dysfunction and subsequent cell death.
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Affiliation(s)
- B Morquette
- 1] Department of Neuroscience, CHUM Research Center, University of Montreal, Montreal, QC, Canada [2] University of Montreal Hospital Research Center (CR-CHUM), Montreal, QC, Canada [3] Groupe de Recherche sur le Système Nerveux Central (GRSNC), University of Montreal, Montreal, QC, Canada
| | - P Morquette
- 1] Department of Neuroscience, CHUM Research Center, University of Montreal, Montreal, QC, Canada [2] Groupe de Recherche sur le Système Nerveux Central (GRSNC), University of Montreal, Montreal, QC, Canada
| | - J Agostinone
- 1] Department of Neuroscience, CHUM Research Center, University of Montreal, Montreal, QC, Canada [2] University of Montreal Hospital Research Center (CR-CHUM), Montreal, QC, Canada [3] Groupe de Recherche sur le Système Nerveux Central (GRSNC), University of Montreal, Montreal, QC, Canada
| | - E Feinstein
- Quark Pharmaceuticals Inc., Research Division, Ness Ziona, Israel
| | - R A McKinney
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
| | - A Kolta
- 1] Department of Neuroscience, CHUM Research Center, University of Montreal, Montreal, QC, Canada [2] Groupe de Recherche sur le Système Nerveux Central (GRSNC), University of Montreal, Montreal, QC, Canada [3] Department of Stomatology, Faculty of Dentistry, University of Montreal, Montreal, QC, Canada
| | - A Di Polo
- 1] Department of Neuroscience, CHUM Research Center, University of Montreal, Montreal, QC, Canada [2] University of Montreal Hospital Research Center (CR-CHUM), Montreal, QC, Canada [3] Groupe de Recherche sur le Système Nerveux Central (GRSNC), University of Montreal, Montreal, QC, Canada
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Larivière R, Gaudet R, Gentil BJ, Girard M, Conte TC, Minotti S, Leclerc-Desaulniers K, Gehring K, McKinney RA, Shoubridge EA, McPherson PS, Durham HD, Brais B. Sacs knockout mice present pathophysiological defects underlying autosomal recessive spastic ataxia of Charlevoix-Saguenay. Hum Mol Genet 2014; 24:727-39. [PMID: 25260547 DOI: 10.1093/hmg/ddu491] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS [MIM 270550]) is an early-onset neurodegenerative disorder caused by mutations in the SACS gene. Over 170 SACS mutations have been reported worldwide and are thought to cause loss of function of sacsin, a poorly characterized and massive 520 kDa protein. To establish an animal model and to examine the pathophysiological basis of ARSACS, we generated Sacs knockout (Sacs(-/-)) mice. Null animals displayed an abnormal gait with progressive motor, cerebellar and peripheral nerve dysfunctions highly reminiscent of ARSACS. These clinical features were accompanied by an early onset, progressive loss of cerebellar Purkinje cells followed by spinal motor neuron loss and peripheral neuropathy. Importantly, loss of sacsin function resulted in abnormal accumulation of non-phosphorylated neurofilament (NF) bundles in the somatodendritic regions of vulnerable neuronal populations, a phenotype also observed in an ARSACS brain. Moreover, motor neurons cultured from Sacs(-/-) embryos exhibited a similar NF rearrangement with significant reduction in mitochondrial motility and elongated mitochondria. The data points to alterations in the NF cytoskeleton and defects in mitochondrial dynamics as the underlying pathophysiological basis of ARSACS.
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Affiliation(s)
- Roxanne Larivière
- Department of Neurology and Neurosurgery, Laboratory of Neurogenetics of Motion and
| | - Rébecca Gaudet
- Department of Neurology and Neurosurgery, Laboratory of Neurogenetics of Motion and
| | - Benoit J Gentil
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada H3A 2B4
| | - Martine Girard
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada H3A 2B4
| | | | - Sandra Minotti
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada H3A 2B4
| | | | - Kalle Gehring
- Groupe de Recherche Axé sur la Structure des Protéines, Department of Biochemistry and
| | - R Anne McKinney
- Department of Pharmacology, McGill University, Montreal, QC, Canada H3G 0B1
| | - Eric A Shoubridge
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada H3A 2B4
| | - Peter S McPherson
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada H3A 2B4
| | - Heather D Durham
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada H3A 2B4
| | - Bernard Brais
- Department of Neurology and Neurosurgery, Laboratory of Neurogenetics of Motion and
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26
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Ilie A, Weinstein E, Boucher A, McKinney RA, Orlowski J. Impaired posttranslational processing and trafficking of an endosomal Na+/H+ exchanger NHE6 mutant (Δ370WST372) associated with X-linked intellectual disability and autism. Neurochem Int 2014; 73:192-203. [DOI: 10.1016/j.neuint.2013.09.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 09/23/2013] [Accepted: 09/24/2013] [Indexed: 01/23/2023]
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27
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Chang PKY, Prenosil GA, Verbich D, Gill R, McKinney RA. Prolonged ampakine exposure prunes dendritic spines and increases presynaptic release probability for enhanced long-term potentiation in the hippocampus. Eur J Neurosci 2014; 40:2766-76. [PMID: 24925283 DOI: 10.1111/ejn.12638] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 04/24/2014] [Accepted: 04/28/2014] [Indexed: 01/19/2023]
Abstract
CX 546, an allosteric positive modulator of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type ionotropic glutamate receptors (AMPARs), belongs to a drug class called ampakines. These compounds have been shown to enhance long-term potentiation (LTP), a cellular model of learning and memory, and improve animal learning task performance, and have augmented cognition in neurodegenerative patients. However, the chronic effect of CX546 on synaptic structures has not been examined. The structure and integrity of dendritic spines are thought to play a role in learning and memory, and their abnormalities have been implicated in cognitive disorders. In addition, their structural plasticity has been shown to be important for cognitive function, such that dendritic spine remodeling has been proposed as the morphological correlate for LTP. Here, we tested the effect of CX546 on dendritic spine remodeling following long-term treatment. We found that, with prolonged CX546 treatment, organotypic hippocampal slice cultures showed a significant reduction in CA3-CA1 excitatory synapse and spine density. Electrophysiological approaches revealed that the CA3-CA1 circuitry compensates for this synapse loss by increasing synaptic efficacy through enhancement of presynaptic release probability. CX546-treated slices showed prolonged and enhanced potentiation upon LTP induction. Furthermore, structural plasticity, namely spine head enlargement, was also more pronounced after CX546 treatment. Our results suggest a concordance of functional and structural changes that is enhanced with prolonged CX546 exposure. Thus, the improved cognitive ability of patients receiving ampakine treatment may result from the priming of synapses through increases in the structural plasticity and functional reliability of hippocampal synapses.
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Affiliation(s)
- Philip K-Y Chang
- Department of Pharmacology & Therapeutics, McGill University, Bellini Life Science Complex, Room 167, 3649 Promenade Sir-William-Osler, Montreal, QC, H3G 0B1, Canada
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28
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Machnes ZM, Huang TCT, Chang PKY, Gill R, Reist N, Dezsi G, Ozturk E, Charron F, O'Brien TJ, Jones NC, McKinney RA, Szyf M. DNA methylation mediates persistent epileptiform activity in vitro and in vivo. PLoS One 2013; 8:e76299. [PMID: 24098468 PMCID: PMC3788713 DOI: 10.1371/journal.pone.0076299] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 08/25/2013] [Indexed: 01/23/2023] Open
Abstract
Epilepsy is a chronic brain disorder involving recurring seizures often precipitated by an earlier neuronal insult. The mechanisms that link the transient neuronal insult to the lasting state of epilepsy are unknown. Here we tested the possible role of DNA methylation in mediating long-term induction of epileptiform activity by transient kainic acid exposure using in vitro and in vivo rodent models. We analyzed changes in the gria2 gene, which encodes for the GluA2 subunit of the ionotropic glutamate, alpha-amino-3-hydroxy-5-methyl-4-isoxazole proprionic acid receptor and is well documented to play a role in epilepsy. We show that kainic acid exposure for two hours to mouse hippocampal slices triggers methylation of a 5’ regulatory region of the gria2 gene. Increase in methylation persists one week after removal of the drug, with concurrent suppression of gria2 mRNA expression levels. The degree of kainic acid-induced hypermethylation of gria2 5’ region varies between individual slices and correlates with the changes in excitability induced by kainic acid. In a rat in vivo model of post kainic acid-induced epilepsy, we show similar hypermethylation of the 5’ region of gria2. Inter-individual variations in gria2 methylation, correlate with the frequency and intensity of seizures among epileptic rats. Luciferase reporter assays support a regulatory role for methylation of gria2 5’ region. Inhibition of DNA methylation by RG108 blocked kainic acid-induced hypermethylation of gria2 5’ region in hippocampal slice cultures and bursting activity. Our results suggest that DNA methylation of such genes as gria2 mediates persistent epileptiform activity and inter-individual differences in the epileptic response to neuronal insult and that pharmacological agents that block DNA methylation inhibit epileptiform activity raising the prospect of DNA methylation inhibitors in epilepsy therapeutics.
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Affiliation(s)
- Ziv M Machnes
- Department of Pharmacology and Therapeutics McGill University, McGill University, Montreal, Quebec, Canada
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29
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Chang PKY, Verbich D, McKinney RA. AMPA receptors as drug targets in neurological disease - advantages, caveats, and future outlook. Eur J Neurosci 2012; 35:1908-16. [DOI: 10.1111/j.1460-9568.2012.08165.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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30
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Verbich D, Prenosil GA, Chang PKY, Murai KK, McKinney RA. Glial glutamate transport modulates dendritic spine head protrusions in the hippocampus. Glia 2012; 60:1067-77. [PMID: 22488940 DOI: 10.1002/glia.22335] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 03/09/2012] [Indexed: 10/28/2022]
Abstract
Accumulating evidence supports the idea that synapses are tripartite, whereby perisynaptic astrocytes modulate both pre- and postsynaptic function. Although some of these features have been uncovered by using electrophysiological methods, less is known about the structural interplay between synapses and glial processes. Here, we investigated how astrocytes govern the plasticity of individual hippocampal dendritic spines. Recently, we uncovered that a subgroup of innervated dendritic spines is able to undergo remodeling by extending spine head protrusions (SHPs) toward neighboring functional presynaptic boutons, resulting in new synapses. Although glutamate serves as a trigger, how this behavior is regulated is unknown. As astrocytes control extracellular glutamate levels through their high-affinity uptake transporters, together with their privileged access to synapses, we investigated a role for astrocytes in SHP formation. Using time-lapse confocal microscopy, we found that the volume overlap between spines and astrocytic processes decreased during the formation of SHPs. Focal application of glutamate also reduced spine-astrocyte overlap and induced SHPs. Importantly, SHP formation was prevented by blocking glial glutamate transporters, suggesting that glial control of extracellular glutamate is important for SHP-mediated plasticity of spines. Hence, the dynamic changes of both spines and astrocytes can rapidly modify synaptic connectivity.
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Affiliation(s)
- David Verbich
- Department of Neurology and Neurosurgery, McGill University, Montréal, QC H3G 0B1, Canada
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Schätzle P, Ster J, Verbich D, McKinney RA, Gerber U, Sonderegger P, Mateos JM. Rapid and reversible formation of spine head filopodia in response to muscarinic receptor activation in CA1 pyramidal cells. J Physiol 2011; 589:4353-64. [PMID: 21768266 DOI: 10.1113/jphysiol.2010.204446] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
A key feature at excitatory synapses is the remodelling of dendritic spines, which in conjunction with receptor trafficking modifies the efficacy of neurotransmission. Here we investigated whether activation of cholinergic receptors, which can modulate synaptic plasticity, also mediates changes in dendritic spine structure. Using confocal time-lapse microscopy in mouse slice cultures we found that brief activation of muscarinic receptors induced the emergence of fine filopodia from spine heads in all CA1 pyramidal cells examined. This response was widespread occurring in 48% of imaged spines, appeared within minutes, was reversible, and was blocked by atropine. Electron microscopic analyses showed that the spine head filopodia (SHFs) extend along the presynaptic bouton. In addition, the decay time of miniature EPSCs was longer after application of the muscarinic acetylcholine receptor agonist methacholine (MCh). Both morphological and electrophysiological changes were reduced by preventing microtubule polymerization with nocodazole. This extension of SHFs during cholinergic receptor activation represents a novel structural form of subspine plasticity that may regulate synaptic properties by fine-tuning interactions between presynaptic boutons and dendritic spines.
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Affiliation(s)
- Philipp Schätzle
- Department of Biochemistry, Centre for Microscopy and Image Analysis, University of Zurich, Winterthurerstrasse, Zurich, Switzerland
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Queval A, Ghattamaneni NR, Perrault CM, Gill R, Mirzaei M, McKinney RA, Juncker D. Chamber and microfluidic probe for microperfusion of organotypic brain slices. Lab Chip 2010; 10:326-34. [PMID: 20091004 DOI: 10.1039/b916669f] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Microfluidic systems are increasingly being used for the culture and study of dissociated cells because they require only minute amounts of materials while enabling drug screening and chemotaxis studies down to the single cell level. However, the culture of organized tissue, such as brain slices, has been more difficult to adapt to microfluidic devices. Here, we present a microfluidic system, comprising (i) a perfusion chamber for the culture of organotypic slices that is compatible with high resolution imaging on inverted microscopes, and (ii) a novel transparent microfluidic probe (MFP) for the localized microperfusion of the brain tissue. The MFP is made in poly(dimethylsiloxane), features six micrometre-scale apertures and can be assembled within a few hours in a standard laboratory. Each aperture can indiscriminately be used either for the injection or aspiration of solutions, giving rise to many possible combinations. The MFP was successfully used for the perfusion of a small number of cells in a brain slice with concurrent confocal fluorescence imaging of the perfused dye and sub-cellular structures within the tissue.
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Affiliation(s)
- Arthur Queval
- Biomedical Engineering Department, McGill University, 740, Dr. Penfield Ave, Montreal, Quebec H3A1A4, Canada
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Abstract
In the central nervous system, most excitatory synapses occur on dendritic spines, which are small protrusions from the dendritic tree. In the mature cortex and hippocampus, dendritic spines are heterogeneous in shape. It has been shown that the shapes of the spine can affect synapse stability and synaptic function. Dendritic spines are highly motile structures that can undergo actin-dependent shape changes, which occur over a time scale ranging from seconds to tens of minutes or even days. The formation, remodelling and elimination of excitatory synapses on dendritic spines represent ways of refining the microcircuitry in the brain. Here I review the current knowledge on the effects of modulation of AMPA and NMDA ionotropic glutamate receptors on dendritic spine formation, motility and remodelling.
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Affiliation(s)
- R Anne McKinney
- Department of Pharmacology and Therapeutics, Bellini Life Science Building, McGill University, Montreal, H3G 0B1, Canada.
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Behrendt M, Sandros MG, McKinney RA, McDonald K, Przybytkowski E, Tabrizian M, Maysinger D. Imaging and organelle distribution of fluorescent InGaP/ZnS nanoparticles in glial cells. Nanomedicine (Lond) 2009; 4:747-61. [DOI: 10.2217/nnm.09.64] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Aim: To assess the effects of oleic acid treatment on subcellular distribution of indium gallium phosphide–zinc sulfide (InGaP/ZnS) nanoparticles in microglia and astrocytes. Materials & methods: The extent of colocalization between the nanoparticles and organelles was assessed by confocal microscopy, spectrofluorometry and cell sorting. Results: Cell treatment with a common fatty acid (oleic acid) within the range of physiological concentrations markedly enhanced the InGaP/ZnS uptake by microglia and afforded their colocalization within lipid droplets/lysosomes but not with mitochondria. Conclusion: These results suggest that the availability of mono-unsaturated fatty acids, such as oleic acid, in different cells could significantly alter nanoparticle uptake and localization, which can in turn affect the functions of cells and tissues coexposed to nanoparticles.
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Affiliation(s)
- Maik Behrendt
- Department of Pharmacology & Therapeutics, McGill University, 3655 Promenade Sir-William-Osler, Montreal, Quebec, H3G 1Y6, Canada
- Department of Biomedicine, Institute of Anatomy, University of Basel, CH-4056 Basel, Switzerland
| | - Marinella G Sandros
- Department of Biomedical Engineering, McGill University, 3775 University Street, Montreal, Quebec, H3A 2B4, Canada
| | - R Anne McKinney
- Department of Pharmacology & Therapeutics, McGill University, 3655 Promenade Sir-William-Osler, Montreal, Quebec, H3G 1Y6, Canada
| | - Ken McDonald
- McGill Flow Cytometry Facility, McGill University, 3649 Promenade Sir-William-Osler, Montreal, Quebec, H3G 0B1, Canada
| | - Ewa Przybytkowski
- Department of Pharmacology & Therapeutics, McGill University, 3655 Promenade Sir-William-Osler, Montreal, Quebec, H3G 1Y6, Canada
| | - Maryam Tabrizian
- Department of Biomedical Engineering, McGill University, 3775 University Street, Montreal, Quebec, H3A 2B4, Canada
| | - Dusica Maysinger
- Department of Pharmacology & Therapeutics, McGill University, 3655 Promenade Sir-William-Osler, Montreal, Quebec, H3G 1Y6, Canada
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Thomas S, Ritter B, Verbich D, Sanson C, Bourbonnière L, McKinney RA, McPherson PS. Intersectin regulates dendritic spine development and somatodendritic endocytosis but not synaptic vesicle recycling in hippocampal neurons. J Biol Chem 2009; 284:12410-9. [PMID: 19258322 DOI: 10.1074/jbc.m809746200] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Intersectin-short (intersectin-s) is a multimodule scaffolding protein functioning in constitutive and regulated forms of endocytosis in non-neuronal cells and in synaptic vesicle (SV) recycling at the neuromuscular junction of Drosophila and Caenorhabditis elegans. In vertebrates, alternative splicing generates a second isoform, intersectin-long (intersectin-l), that contains additional modular domains providing a guanine nucleotide exchange factor activity for Cdc42. In mammals, intersectin-s is expressed in multiple tissues and cells, including glia, but excluded from neurons, whereas intersectin-l is a neuron-specific isoform. Thus, intersectin-I may regulate multiple forms of endocytosis in mammalian neurons, including SV endocytosis. We now report, however, that intersectin-l is localized to somatodendritic regions of cultured hippocampal neurons, with some juxtanuclear accumulation, but is excluded from synaptophysin-labeled axon terminals. Consistently, intersectin-l knockdown (KD) does not affect SV recycling. Instead intersectin-l co-localizes with clathrin heavy chain and adaptor protein 2 in the somatodendritic region of neurons, and its KD reduces the rate of transferrin endocytosis. The protein also co-localizes with F-actin at dendritic spines, and intersectin-l KD disrupts spine maturation during development. Our data indicate that intersectin-l is indeed an important regulator of constitutive endocytosis and neuronal development but that it is not a prominent player in the regulated endocytosis of SVs.
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Affiliation(s)
- Sébastien Thomas
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
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Hugel S, Abegg M, de Paola V, Caroni P, Gähwiler BH, McKinney RA. Dendritic spine morphology determines membrane-associated protein exchange between dendritic shafts and spine heads. ACTA ACUST UNITED AC 2008; 19:697-702. [PMID: 18653666 DOI: 10.1093/cercor/bhn118] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The purpose of this study was to examine whether variability in the shape of dendritic spines affects protein movement within the plasma membrane. Using a combination of confocal microscopy and the fluorescence loss in photobleaching technique in living hippocampal CA1 pyramidal neurons expressing membrane-linked GFP, we observed a clear correlation between spine shape parameters and the diffusion and compartmentalization of membrane-associated proteins. The kinetics of membrane-linked GFP exchange between the dendritic shaft and the spine head compartment were slower in dendritic spines with long necks and/or large heads than in those with short necks and/or small heads. Furthermore, when the spine area was reduced by eliciting epileptiform activity, the kinetics of protein exchange between the spine compartments exhibited a concomitant decrease. As synaptic plasticity is considered to involve the dynamic flux by lateral diffusion of membrane-bound proteins into and out of the synapse, our data suggest that spine shape represents an important parameter in the susceptibility of synapses to undergo plastic change.
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Affiliation(s)
- Sylvain Hugel
- Brain Research Institute, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
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Mateos JM, Lüthi A, Savic N, Stierli B, Streit P, Gähwiler BH, McKinney RA. Synaptic modifications at the CA3-CA1 synapse after chronic AMPA receptor blockade in rat hippocampal slices. J Physiol 2007; 581:129-38. [PMID: 17303644 PMCID: PMC2075211 DOI: 10.1113/jphysiol.2006.120550] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Maintenance of dendritic spines, the postsynaptic elements of most glutamatergic synapses in the central nervous system, requires continued activation of AMPA receptors. In organotypic hippocampal slice cultures, chronic blockade of AMPA receptors for 14 days induces a substantial loss of dendritic spines on CA1 pyramidal neurons. Here, using serial section electron microscopy, we show that loss of dendritic spines is paralleled by a significant reduction in synapse density. In contrast, we observed an increased number of asymmetric synapses onto the dendritic shaft, suggesting that spine retraction does not inevitably lead to synapse elimination. Functional analysis of the remaining synapses revealed that hippocampal circuitry compensates for the anatomical loss of synapses by increasing synaptic efficacy. Moreover, we found that the observed morphological and functional changes were associated with altered bidirectional synaptic plasticity. We conclude that continued activation of AMPA receptors is necessary for maintaining structure and function of central glutamatergic synapses.
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Affiliation(s)
- José María Mateos
- Brain Research Institute, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
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39
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Abstract
The vast majority of excitatory connections in the hippocampus are made on dendritic spines. Both dendritic spines and molecules within the membrane are able to move, but the physiological role of these movements is unclear. In the developing brain, spines show highly dynamic behaviour thought to facilitate new synaptic connections. Dynamic movements also occur in adults but the role of this movement is unclear. We have studied the effects of the most important excitatory neurotransmitter, glutamate, and found receptor activation to enhance movement of molecules within the spine membrane. This action of glutamate may be important in regulating the trafficking of neurotransmitter receptors that mediate change in synaptic function. In addition, we have studied the dynamic interactions between pre- and postsynaptic structures labelled with FM 4-64 and a membrane-targeted GFP (green fluorescent protein), respectively, in hippocampal slice cultures under conditions of increased activity, such as epilepsy. Our findings suggest a novel form of activity-dependent synaptic plasticity where spontaneous glutamate release is sufficient to trigger changes in the hippocampal microcircuitry by attracting neighbouring spines responsive to an enhanced level of extracellular glutamate.
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Affiliation(s)
- R A McKinney
- Department of Pharmacology and Therapeutics, McIntyre Medical Sciences Building, McGill University, Promenade Sir-William-Osler, Montréal, QC, Canada H3G 1Y6.
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Richards DA, Mateos JM, Hugel S, de Paola V, Caroni P, Gähwiler BH, McKinney RA. Glutamate induces the rapid formation of spine head protrusions in hippocampal slice cultures. Proc Natl Acad Sci U S A 2005; 102:6166-71. [PMID: 15831587 PMCID: PMC556130 DOI: 10.1073/pnas.0501881102] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Synaptic plasticity at neuronal connections has been well characterized functionally by using electrophysiological approaches, but the structural basis for this phenomenon remains controversial. We have studied the dynamic interactions between presynaptic and postsynaptic structures labeled with FM 4-64 and a membrane-targeted GFP, respectively, in hippocampal slices. Under conditions of reduced neuronal activity (1 muM tetrodotoxin), we observed extension of glutamate receptor-dependent processes from dendritic spines of CA1 pyramidal cells to presynaptic boutons. The formation of these spine head protrusions is blocked by alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor antagonists and by agents that reduce the release of glutamate from presynaptic terminals. Moreover, spine head protrusions form in response to exogenously applied glutamate, with clear directionality toward the glutamate electrode. Our results suggest that spontaneously released glutamate is sufficient to activate nearby spines, which can then lead to the growth of new postsynaptic processes connecting to a presynaptic site. Spines thus can compare their recent history with that of neighboring synapses and modify local connectivity accordingly.
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Affiliation(s)
- David A Richards
- Brain Research Institute, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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Richards DA, De Paola V, Caroni P, Gähwiler BH, McKinney RA. AMPA-receptor activation regulates the diffusion of a membrane marker in parallel with dendritic spine motility in the mouse hippocampus. J Physiol 2004; 558:503-12. [PMID: 15169845 PMCID: PMC1664965 DOI: 10.1113/jphysiol.2004.062091] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Dendritic spines are the site of most excitatory connections in the hippocampus. We have investigated the diffusibility of a membrane-bound green fluorescent protein (mGFP) within the inner leaflet of the plasma membrane using Fluorescence Recovery After Photobleaching. In dendritic spines the diffusion of mGFP was significantly retarded relative to the dendritic shaft. In parallel, we have assessed the motility of dendritic spines, and found an inverse correlation between spine motility and the rate of diffusion of mGFP. We then tested the influence of glutamate receptor activation or blockade, and the involvement of the actin cytoskeleton (using latrunculin A) on spine motility and mGFP diffusion. These results show that glutamate receptors regulate the mobility of molecules in the inner leaflet of the plasma membrane through an action upon the actin cytoskeleton, suggesting a novel mechanism for the regulation of postsynaptic receptor density and composition.
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Affiliation(s)
- D A Richards
- Brain Research Institute, University of Zurich, Zurich, Switzerland.
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42
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Abstract
Although epileptic seizures are characterized by excessive excitation, the role of excitatory synaptic transmission in the induction and expression of epilepsy remains unclear. Here, we show that epileptiform activity strengthens excitatory hippocampal synapses by increasing the number of functional (RS)-alpha-amino-3hydroxy-5methyl-4-isoxadepropionate (AMPA)-type glutamate receptors in CA3-CA1 synapses. This form of synaptic strengthening occludes long-term potentiation (LTP) and enhances long-term depression (LTD), processes involved in learning and memory. These changes in synaptic transmission and plasticity, which are fully blocked with N-methyl-D-aspartate (NMDA) receptor antagonists, may underlie epilepsy induction and seizure-associated memory deficits.
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Affiliation(s)
- Mathias H Abegg
- Brain Research Institute, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
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Savić N, Lüthi A, Gähwiler BH, McKinney RA. N-methyl-D-aspartate receptor blockade during development lowers long-term potentiation threshold without affecting dynamic range of CA3-CA1 synapses. Proc Natl Acad Sci U S A 2003; 100:5503-8. [PMID: 12702771 PMCID: PMC154374 DOI: 10.1073/pnas.0831035100] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During development, excitatory synapses in the CA1 region of the hippocampus undergo activity-dependent and N-methyl-D-aspartate (NMDA) receptor-dependent long-lasting changes in synaptic efficacy. These bidirectional changes occur between limits that determine the dynamic range within which synapses operate. It is unknown whether the dynamic range itself is also activity-dependent and NMDA receptor-dependent. Here, we show that chronic blockade of NMDA receptors in hippocampal slice cultures during early postnatal development does not affect the dynamic range but results in a lower threshold for the induction of long-term potentiation. Thus, the dynamic range of CA3-CA1 synapses, unlike long-term potentiation threshold, is NMDA receptor-independent, thereby providing functional stability to the hippocampal network during development.
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Affiliation(s)
- Natasa Savić
- Brain Research Institute, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
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Niederöst B, Oertle T, Fritsche J, McKinney RA, Bandtlow CE. Nogo-A and myelin-associated glycoprotein mediate neurite growth inhibition by antagonistic regulation of RhoA and Rac1. J Neurosci 2002; 22:10368-76. [PMID: 12451136 PMCID: PMC6758757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2023] Open
Abstract
The adult mammalian CNS has a limited capacity for nerve regeneration and structural plasticity. The presence of glia-derived inhibitory factors myelin-associated glycoprotein (MAG) and Nogo-A have been suggested to provide a nonpermissive environment for elongating nerve fibers. In particular, Nogo-A, an integral membrane protein predominantly expressed by oligodendrocytes, has been demonstrated to impair neurite growth in vitro and in vivo. Structure function analysis revealed that Nogo-A protein contains at least two active domains, NiG and Nogo-66, with diverse effects on neurite outgrowth and cell spreading. We now provide evidence that these inhibitory domains mediate their effects via an antagonistic regulation of the small GTPases RhoA and Rac1, resulting in activation of RhoA and suppression of Rac1. By inactivating RhoA with C3 transferase or the downstream effector Rho-kinase ROCK with, the inhibitory effects of both Nogo-A fragments and MAG on neurite outgrowth and oligodendrocyte-mediated growth cone collapse were abolished. Furthermore, we show that the recently cloned receptor for Nogo-66 and MAG, NgR, is not necessary for either NiG- or MAG-induced RhoA activation.
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Affiliation(s)
- Barbara Niederöst
- Institute of Medical Chemistry and Biochemistry, Leopold-Franzens-University of Innsbruck, A-6020 Innsbruck, Austria
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45
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Koller D, Born W, Leuthäuser K, Flühmann B, McKinney RA, Fischer JA, Muff R. The extreme N-terminus of the calcitonin-like receptor contributes to the selective interaction with adrenomedullin or calcitonin gene-related peptide. FEBS Lett 2002; 531:464-8. [PMID: 12435594 DOI: 10.1016/s0014-5793(02)03585-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The calcitonin (CT)-like (CL) receptor is a CT gene-related peptide (CGRP) receptor or an adrenomedullin (AM) receptor when co-expressed with receptor-activity-modifying proteins (RAMP) 1 or 2, respectively. The CL receptor shows 57% overall sequence identity with the CT receptor, but the homology is much lower in the extreme N-terminus. An N-terminal deletion mutant of the human (h) CL receptor (Delta18-hCL) and a chimeric receptor consisting of the N-terminal amino acids of the porcine (p) CT receptor fused to the Delta18-hCL receptor (pCT-hCL) were therefore analyzed. The Delta18-hCL receptor function was abolished when co-expressed with RAMP1 or -2. The pCT-hCL receptor was a fully functional CGRP receptor when co-expressed with RAMP1, but the RAMP2-dependent AM receptor function was impaired. Limited sequence similarities in the N-terminus of the pCT and the hCL receptors rescue CGRP but not AM receptor binding and signalling.
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Affiliation(s)
- Daniela Koller
- Research Laboratory for Calcium Metabolism, Departments of Orthopaedic Surgery and Medicine, University of Zurich, Klinik Balgrist, Forchstrasse 340, 8008, Zurich, Switzerland
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46
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Schwyzer L, Mateos JM, Abegg M, Rietschin L, Heeb L, Thompson SM, Lüthi A, Gähwiler BH, McKinney RA. Physiological and morphological plasticity induced by chronic treatment with NT-3 or NT-4/5 in hippocampal slice cultures. Eur J Neurosci 2002; 16:1939-48. [PMID: 12453058 DOI: 10.1046/j.1460-9568.2002.02259.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Expression of neurotrophins (NTs) and their receptors is elevated in the adult CNS under several neuropathological conditions. We have investigated the anatomical and electrophysiological consequences of chronic NT-3 or NT-4/5 treatment on established organotypic hippocampal slice cultures maintained in vitro for > 14 days. Both NT-3 and NT-4/5 increased spontaneous, action potential-dependent excitatory synaptic activity (sEPSCs), but only NT-3 increased inhibitory synaptic activity (sIPSCs) in CA3 pyramidal cells. Both NTs strongly promoted spontaneous synaptic bursting activity. Spontaneous bursts of EPSCs were observed after either NT treatment but only NT-3-treated cultures exhibited an increase in spontaneous bursts of IPSCs. In addition, sIPSC bursts were eliminated by blocking glutamatergic excitation. The frequency of miniature inhibitory postsynaptic currents, but not miniature excitatory postsynaptic currents, was also increased by both NT-3 and NT-4/5. Furthermore, NT-3 and NT-4/5 induced an up-regulation of the growth-associated protein GAP-43, suggesting that neurotrophins may be able to induce axonal reorganization in established neuronal networks. CA1 pyramidal cells exhibited slight alterations in dendritic branching after NT-4/5, but not NT-3 treatment. We conclude that chronic treatment with NT-3 or NT-4/5 can affect an established hippocampal network by elevating spontaneous inhibitory and excitatory synaptic activity and inducing coordinated pre- and postsynaptic structural changes.
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Affiliation(s)
- Lucia Schwyzer
- Brain Research Institute, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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McKinney RA, Lake JL, Charpentier MA, Ryba S. Using mussel isotope ratios to assess anthropogenic nitrogen inputs to freshwater ecosystems. Environ Monit Assess 2002; 74:167-192. [PMID: 11878641 DOI: 10.1023/a:1013824220299] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Stable nitrogen isotope ratios (delta15N) of freshwater mussels from a series of lakes and ponds were related to watershed land use characteristics to assess their utility in determining the source of nitrogen inputs to inland water bodies. Nitrogen isotope ratios measured in freshwater mussels from 19 lakes and ponds in Rhode Island, U.S.A., ranged from 4.9-12.6 per thousand and were found to significantly correlate with the fraction of residential development in 100 and 200 m buffer zones around the ponds. Mussel delta15N values in 12 of the 19 ponds also showed significant correlation with average dissolved nitrate concentrations, which ranged from 23-327 microg L(-1). These observations, in light of previous studies which link elevated delta15N values of nitrogen derived from septic wastewater with those seen in biota, suggest that mussel isotope ratios may reflect nitrogen source in freshwater ecosystems. We followed an iterative approach using multiple regression analysis to assess the relationship between mussel delta15N and the land use categories fraction residential development, fraction feedlot agriculture, fraction row-crop agriculture, and fraction natural vegetation in 100 and 200 m buffer zones and pond watersheds. From this we developed a simple regression model to predict mussel delta15N from the fraction of residential development in the 200 m buffer zone around the pond. Subsequent testing with data from 16 additional sites in the same ecoregion led us to refine the model by incorporating the fraction of natural vegetation. The overall average absolute difference between measured and predicted delta15N values using the two-parameter model was 1.6 per thousand. Potential sources of error in the model include differences in the scale and categorization of land-use data used to generate and test the model, differences in physical characteristics, such as retention time and range of residential development, and exclusion of sources of enriched nitrogen such as runoff from feedlot operations or increased nitrogen loading from inefficient or failed septic systems.
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Affiliation(s)
- R A McKinney
- US Environmental Protection Agency, Atlantic Ecology Division, Narragansett, Rhode Island, USA.
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Lüthi A, Schwyzer L, Mateos JM, Gähwiler BH, McKinney RA. NMDA receptor activation limits the number of synaptic connections during hippocampal development. Nat Neurosci 2001; 4:1102-7. [PMID: 11687815 DOI: 10.1038/nn744] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Activity-dependent synaptic plasticity triggered by N-methyl-d-aspartate (NMDA) receptor activation is a fundamental property of many glutamatergic synapses and may be critical for the shaping and refinement of the structural and functional properties of neuronal circuits during early postnatal development. Using a combined morphological and electrophysiological approach, we showed that chronic blockade of NMDA receptors in hippocampal slice cultures during the first two weeks of postnatal development leads to a substantial increase in synapse number and results in a more complex dendritic arborization of CA1 pyramidal cells. Thus, the development of excitatory circuitry in the hippocampus is determined by two opposing processes: NMDA receptor-independent synapse formation and NMDA receptor-dependent attenuation of synaptogenesis.
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Affiliation(s)
- A Lüthi
- Brain Research Institute, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
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49
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Fauquier T, Guérineau NC, McKinney RA, Bauer K, Mollard P. Folliculostellate cell network: a route for long-distance communication in the anterior pituitary. Proc Natl Acad Sci U S A 2001; 98:8891-6. [PMID: 11438713 PMCID: PMC37531 DOI: 10.1073/pnas.151339598] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
All higher life forms critically depend on hormones being rhythmically released by the anterior pituitary. The proper functioning of this master gland is dynamically controlled by a complex set of regulatory mechanisms that ultimately determine the fine tuning of the excitable endocrine cells, all of them heterogeneously distributed throughout the gland. Here, we provide evidence for an intrapituitary communication system by which information is transferred via the network of nonendocrine folliculostellate (FS) cells. Local electrical stimulation of FS cells in acute pituitary slices triggered cytosolic calcium waves, which propagated to other FS cells by signaling through gap junctions. Calcium wave initiation was because of the membrane excitability of FS cells, hitherto classified as silent cells. FS cell coupling could relay information between opposite regions of the gland. Because FS cells respond to central and peripheral stimuli and dialogue with endocrine cells, the form of large-scale intrapituitary communication described here may provide an efficient mechanism that orchestrates anterior pituitary functioning in response to physiological needs.
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Affiliation(s)
- T Fauquier
- Institut National de la Santé et de la Recherche Médicale Unité 469, Centre National de la Recherche Scientifique-INSERM de Pharmacologie-Endocrinologie, 141 Rue de la Cardonille, 34094 Montpellier Cedex 5, France
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50
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Mills LJ, Gutjahr-Gobell RE, Haebler RA, Horowitz DJ, Jayaraman S, Pruell RJ, McKinney RA, Gardner GR, Zaroogian GE. Effects of estrogenic (o,p'-DDT; octylphenol) and anti-androgenic (p,p'-DDE) chemicals on indicators of endocrine status in juvenile male summer flounder (Paralichthys dentatus). Aquat Toxicol 2001; 52:157-176. [PMID: 11164537 DOI: 10.1016/s0166-445x(00)00139-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Laboratory experiments were conducted with male summer flounder to assess the value of selected measures of endocrine status in fish as indicators of exposure to endocrine-disrupting contaminants. Effects of 1,1,1-trichloro-2-(p-chlorophenyl)-2-(o-chlorophenyl) ethane (o,p'-DDT), octylphenol and 1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p'-DDE) on hepatosomatic and gonadosomatic indices, plasma steroid hormone levels, vitellogenin production, and gonadal development were evaluated in laboratory-raised, juvenile male summer flounder. Flounder were injected twice with test chemical in a coconut oil carrier. Each chemical was tested at three different concentrations. Estrogenic (o,p'-DDT; octylphenol) and anti-androgenic (p,p'-DDE) chemicals were evaluated alone and in combination (octylphenol plus o,p'-DDT or p,p'-DDE). Additionally, some fish were treated with the natural ligand for the estrogen receptor, 17beta-estradiol. Blood and tissues from different fish in each treatment were sampled 4, 6 and 8 weeks after the first injection. Fish exposed to a combination of o,p'-DDT plus octylphenol were also sampled after 15 weeks. In all cases, responses of fish exposed to a test chemical were compared to control fish sampled at the same time. The following significant differences, relative to controls, were observed in at least one sampling time or at least one concentration of chemical. 17beta-Estradiol-treated flounder exhibited decreased gonadosomatic index (GSI), altered hepatosomatic index (HSI), elevated plasma estradiol, reduced plasma testosterone, and high levels of plasma vitellogenin. Fish treated with o,p'-DDT showed lower GSI, no change in HSI or plasma estradiol, depression of plasma testosterone, and induction of vitellogenesis. Octylphenol treatment resulted in lower GSI, no change in HSI, initially increased plasma estradiol and decreased testosterone, and no vitellogenin production. p,p'-DDE treatment did not significantly alter any indicator relative to controls. In experiments using combinations of chemicals, flounder receiving o,p'-DDT plus octylphenol had lower GSI after 8 weeks and elevated plasma estradiol after 15 weeks exposure. Fish treated with p,p'-DDE plus octylphenol for 8 weeks exhibited a significantly lower GSI. Overall, lower GSI and plasma testosterone levels, relative to controls, were consistent indicators of exposure to estrogenic chemicals in juvenile male flounder. No indicators were found that would identify exposure to the mammalian anti-androgen p,p'-DDE.
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Affiliation(s)
- L J Mills
- National Health and Environmental Effects Laboratory, Atlantic Ecology Division, US Environmental Protection Agency, 27 Tarzwell Drive, Narragansett, RI 02882, USA.
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