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Johnson KO, Harel L, Triplett JW. Postsynaptic NMDA Receptor Expression Is Required for Visual Corticocollicular Projection Refinement in the Mouse Superior Colliculus. J Neurosci 2023; 43:1310-1320. [PMID: 36717228 PMCID: PMC9987568 DOI: 10.1523/jneurosci.1473-22.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 11/09/2022] [Accepted: 11/13/2022] [Indexed: 01/31/2023] Open
Abstract
Efficient sensory processing of spatial information is facilitated through the organization of neuronal connections into topographic maps of space. In integrative sensory centers, converging topographic maps must be aligned to merge spatially congruent information. The superior colliculus (SC) receives topographically ordered visual inputs from retinal ganglion cells (RGCs) in the eye and layer 5 neurons in the primary visual cortex (L5-V1). Previous studies suggest that RGCs instruct the alignment of later-arriving L5-V1 inputs in an activity-dependent manner. However, the molecular mechanisms underlying this remain unclear. Here, we explored the role of NMDA receptors in visual map alignment in the SC using a conditional genetic knockout approach. We leveraged a novel knock-in mouse line that expresses tamoxifen-inducible Cre recombinase under the control of the Tal1 gene (Tal1CreERT2 ), which we show allows for specific recombination in the superficial layers of the SC. We used Tal1CreERT2 mice of either sex to conditionally delete the obligate GluN1 subunit of the NMDA receptor (SC-cKO) during the period of visual map alignment. We observed a significant disruption of L5-V1 axon terminal organization in the SC of SC-cKO mice. Importantly, retinocollicular topography was unaffected in this context, suggesting that alignment is also disrupted. Time-course experiments suggest that NMDA receptors may play a critical role in the refinement of L5-V1 inputs in the SC. Together, these data implicate NMDA receptors as critical mediators of activity-dependent visual map alignment in the SC.SIGNIFICANCE STATEMENT Alignment of topographic inputs is critical for integration of spatially congruent sensory information; however, little is known about the mechanisms underlying this complex process. Here, we took a conditional genetic approach to explore the role of NMDA receptors in the alignment of retinal and cortical visual inputs in the superior colliculus. We characterize a novel mouse line providing spatial and temporal control of recombination in the superior colliculus and reveal a critical role for NMDA expression in visual map alignment. These data support a role for neuronal activity in visual map alignment and provide mechanistic insight into this complex developmental process.
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Affiliation(s)
- Kristy O Johnson
- Center for Neuroscience Research, Children's National Research Institute, Washington, DC 20010
- Institute for Biomedical Sciences, George Washington University School of Medicine, Washington, DC 20037
| | - Leeor Harel
- Center for Neuroscience Research, Children's National Research Institute, Washington, DC 20010
| | - Jason W Triplett
- Center for Neuroscience Research, Children's National Research Institute, Washington, DC 20010
- Institute for Biomedical Sciences, George Washington University School of Medicine, Washington, DC 20037
- Department of Pediatrics, George Washington University School of Medicine, Washington, DC 20037
- Department of Pharmacology and Physiology, George Washington University School of Medicine, Washington, DC 20037
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Willis EF, MacDonald KPA, Nguyen QH, Garrido AL, Gillespie ER, Harley SBR, Bartlett PF, Schroder WA, Yates AG, Anthony DC, Rose-John S, Ruitenberg MJ, Vukovic J. Repopulating Microglia Promote Brain Repair in an IL-6-Dependent Manner. Cell 2020; 180:833-846.e16. [PMID: 32142677 DOI: 10.1016/j.cell.2020.02.013] [Citation(s) in RCA: 250] [Impact Index Per Article: 62.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 11/21/2019] [Accepted: 02/05/2020] [Indexed: 12/20/2022]
Abstract
Cognitive dysfunction and reactive microglia are hallmarks of traumatic brain injury (TBI), yet whether these cells contribute to cognitive deficits and secondary inflammatory pathology remains poorly understood. Here, we show that removal of microglia from the mouse brain has little effect on the outcome of TBI, but inducing the turnover of these cells through either pharmacologic or genetic approaches can yield a neuroprotective microglial phenotype that profoundly aids recovery. The beneficial effects of these repopulating microglia are critically dependent on interleukin-6 (IL-6) trans-signaling via the soluble IL-6 receptor (IL-6R) and robustly support adult neurogenesis, specifically by augmenting the survival of newborn neurons that directly support cognitive function. We conclude that microglia in the mammalian brain can be manipulated to adopt a neuroprotective and pro-regenerative phenotype that can aid repair and alleviate the cognitive deficits arising from brain injury.
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Affiliation(s)
- Emily F Willis
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Kelli P A MacDonald
- Department of Immunology, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Quan H Nguyen
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Adahir Labrador Garrido
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Ellen R Gillespie
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Samuel B R Harley
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Perry F Bartlett
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Wayne A Schroder
- Department of Immunology, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia; School of Environment and Science, Griffith University, QLD, Brisbane, Australia
| | - Abi G Yates
- Laboratory of Experimental Neuropathology, Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK
| | - Daniel C Anthony
- Laboratory of Experimental Neuropathology, Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK
| | - Stefan Rose-John
- Biochemisches Institut, Christian Albrechts Universität Kiel, Kiel, Germany
| | - Marc J Ruitenberg
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Jana Vukovic
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia.
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Koyama H, Zhang Z, Ijuin R, Siqin, Son J, Hatta Y, Ohta M, Wakao M, Hosoya T, Doi H, Suzuki M. Pd0-mediated rapid coupling of methyl iodide with excess amounts of benzyl- and cinnamylboronic acid esters: efficient method for incorporation of positron-emitting 11C radionuclide into organic frameworks by coupling between two sp3-hybridized carbons. RSC Adv 2013. [DOI: 10.1039/c3ra40815a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
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Jeong Y, Dolson DK, Waclaw RR, Matise MP, Sussel L, Campbell K, Kaestner KH, Epstein DJ. Spatial and temporal requirements for sonic hedgehog in the regulation of thalamic interneuron identity. Development 2011; 138:531-41. [PMID: 21205797 DOI: 10.1242/dev.058917] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In caudal regions of the diencephalon, sonic hedgehog (Shh) is expressed in the ventral midline of prosomeres 1-3 (p1-p3), which underlie the pretectum, thalamus and prethalamus, respectively. Shh is also expressed in the zona limitans intrathalamica (zli), a dorsally projecting spike that forms at the p2-p3 boundary. The presence of two Shh signaling centers in the thalamus has made it difficult to determine the specific roles of either one in regional patterning and neuronal fate specification. To investigate the requirement of Shh from a focal source of expression in the ventral midline of the diencephalon, we used a newly generated mouse line carrying a targeted deletion of the 525 bp intronic sequence mediating Shh brain enhancer-1 (SBE1) activity. In SBE1 mutant mice, Shh transcription was initiated but not maintained in the ventral midline of the rostral midbrain and caudal diencephalon, yet expression in the zli was unaffected. In the absence of ventral midline Shh, rostral thalamic progenitors (pTH-R) adopted the molecular profile of a more caudal thalamic subtype (pTH-C). Surprisingly, despite their early mis-specification, neurons derived from the pTH-R domain continued to migrate to their proper thalamic nucleus, extended axons along their normal trajectory and expressed some, but not all, of their terminal differentiation markers. Our results, and those of others, suggest a model whereby Shh signaling from distinct spatial and temporal domains in the diencephalon exhibits unique and overlapping functions in the development of discrete classes of thalamic interneurons.
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Affiliation(s)
- Yongsu Jeong
- Department of Genetic Engineering, College of Life Science and Graduate School of Biotechnology, Kyung Hee University, Yongin-si, Gyeonggi-do, Republic of Korea
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Kotloski R, McNamara JO. Reduction of TrkB expression de novo in the adult mouse impairs epileptogenesis in the kindling model. Hippocampus 2010; 20:713-23. [PMID: 19603519 DOI: 10.1002/hipo.20673] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Elucidating the mechanisms of epileptogenesis in molecular terms can identify targets for therapies aimed at preventing epileptogenesis or limiting its progression. Genetic perturbations have implicated signaling by the neurotrophin, BDNF, and its receptor, TrkB, in limbic epileptogenesis. Whether this signaling is critical to epileptogenesis in the adult brain is unclear. We sought to determine whether reduced expression of TrkB de novo in the mature brain is sufficient to impair epileptogenesis in the kindling model. Treatment of adult Act-CreER TrkB(flox/flox) mice with tamoxifen resulted in modest reductions of TrkB protein expression de novo in the adult that were detected in hippocampus but not other brain regions. Modest reduction of hippocampal TrkB content inhibited epileptogenesis induced by stimulation of hippocampus or amygdala. The data support the conclusion that reduction of TrkB expression in hippocampus de novo in the mature brain impairs epileptogenesis in the kindling model. These findings advance TrkB and its downstream signaling pathways as attractive targets for limiting the progression of epileptogenesis.
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Affiliation(s)
- Robert Kotloski
- Department of Neurology, Wake Forest University Baptist Medical Center, Winston-Salem, North Carolina 27157, USA
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