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Manuel M, Tan KB, Kozic Z, Molinek M, Marcos TS, Razak MFA, Dobolyi D, Dobie R, Henderson BEP, Henderson NC, Chan WK, Daw MI, Mason JO, Price DJ. Pax6 limits the competence of developing cerebral cortical cells to respond to inductive intercellular signals. PLoS Biol 2022; 20:e3001563. [PMID: 36067211 PMCID: PMC9481180 DOI: 10.1371/journal.pbio.3001563] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [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: 01/21/2022] [Revised: 09/16/2022] [Accepted: 07/08/2022] [Indexed: 12/13/2022] Open
Abstract
The development of stable specialized cell types in multicellular organisms relies on mechanisms controlling inductive intercellular signals and the competence of cells to respond to such signals. In developing cerebral cortex, progenitors generate only glutamatergic excitatory neurons despite being exposed to signals with the potential to initiate the production of other neuronal types, suggesting that their competence is limited. Here, we tested the hypothesis that this limitation is due to their expression of transcription factor Pax6. We used bulk and single-cell RNAseq to show that conditional cortex-specific Pax6 deletion from the onset of cortical neurogenesis allowed some progenitors to generate abnormal lineages resembling those normally found outside the cortex. Analysis of selected gene expression showed that the changes occurred in specific spatiotemporal patterns. We then compared the responses of control and Pax6-deleted cortical cells to in vivo and in vitro manipulations of extracellular signals. We found that Pax6 loss increased cortical progenitors’ competence to generate inappropriate lineages in response to extracellular factors normally present in developing cortex, including the morphogens Shh and Bmp4. Regional variation in the levels of these factors could explain spatiotemporal patterns of fate change following Pax6 deletion in vivo. We propose that Pax6’s main role in developing cortical cells is to minimize the risk of their development being derailed by the potential side effects of morphogens engaged contemporaneously in other essential functions. The development of stable specialized cell types in multicellular organisms relies on mechanisms controlling inductive intercellular signals and the competence of cells to respond. This study shows that cortical development is stabilized by the protective actions of the transcription factor Pax6, which adjusts the ability of cortical cells to respond to potentially destabilizing signals present in their local environment.
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Affiliation(s)
- Martine Manuel
- Simons Initiative for the Developing Brain, Patrick Wild Centre, University of Edinburgh, Edinburgh, United Kingdom
| | - Kai Boon Tan
- Simons Initiative for the Developing Brain, Patrick Wild Centre, University of Edinburgh, Edinburgh, United Kingdom
| | - Zrinko Kozic
- Simons Initiative for the Developing Brain, Patrick Wild Centre, University of Edinburgh, Edinburgh, United Kingdom
| | - Michael Molinek
- Simons Initiative for the Developing Brain, Patrick Wild Centre, University of Edinburgh, Edinburgh, United Kingdom
| | - Tiago Sena Marcos
- Simons Initiative for the Developing Brain, Patrick Wild Centre, University of Edinburgh, Edinburgh, United Kingdom
| | - Maizatul Fazilah Abd Razak
- Simons Initiative for the Developing Brain, Patrick Wild Centre, University of Edinburgh, Edinburgh, United Kingdom
| | - Dániel Dobolyi
- Simons Initiative for the Developing Brain, Patrick Wild Centre, University of Edinburgh, Edinburgh, United Kingdom
| | - Ross Dobie
- Centre for Inflammation Research, University of Edinburgh, Queen’s Medical Research Institute, Edinburgh, United Kingdom
| | - Beth E. P. Henderson
- Centre for Inflammation Research, University of Edinburgh, Queen’s Medical Research Institute, Edinburgh, United Kingdom
| | - Neil C. Henderson
- Centre for Inflammation Research, University of Edinburgh, Queen’s Medical Research Institute, Edinburgh, United Kingdom
| | - Wai Kit Chan
- Simons Initiative for the Developing Brain, Patrick Wild Centre, University of Edinburgh, Edinburgh, United Kingdom
| | - Michael I. Daw
- Simons Initiative for the Developing Brain, Patrick Wild Centre, University of Edinburgh, Edinburgh, United Kingdom
- Zhejiang University-University of Edinburgh Institute, Zhejiang University, Haining, Zhejiang, People’s Republic of China
| | - John O. Mason
- Simons Initiative for the Developing Brain, Patrick Wild Centre, University of Edinburgh, Edinburgh, United Kingdom
| | - David J. Price
- Simons Initiative for the Developing Brain, Patrick Wild Centre, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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Currie SP, Luz LL, Booker SA, Wyllie DJA, Kind PC, Daw MI. Reduced local input to fast-spiking interneurons in the somatosensory cortex in the GABA A γ2 R43Q mouse model of absence epilepsy. Epilepsia 2017; 58:597-607. [PMID: 28195311 PMCID: PMC5412680 DOI: 10.1111/epi.13693] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [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] [Accepted: 01/04/2017] [Indexed: 02/04/2023]
Abstract
Objective Absence seizures in childhood absence epilepsy are initiated in the thalamocortical (TC) system. We investigated if these seizures result from altered development of the TC system before the appearance of seizures in mice containing a point mutation in γ‐aminobutyric acid A (GABAA) receptor γ2 subunits linked to childhood absence epilepsy (R43Q). Findings from conditional mutant mice indicate that expression of normal γ2 subunits during preseizure ages protect from later seizures. This indicates that altered development in the presence of the R43Q mutation is a key contributor to the R43Q phenotype. We sought to identify the cellular processes affected by the R43Q mutation during these preseizure ages. Methods We examined landmarks of synaptic development at the end of the critical period for somatosensory TC plasticity using electrophysiologic recordings in TC brain slices from wild‐type mice and R43Q mice. Results We found that the level of TC connectivity to layer 4 (L4) principal cells and the properties of TC synapses were unaltered in R43Q mice. Furthermore, we show that, although TC feedforward inhibition and the total level of GABAergic inhibition were normal, there was a reduction in the local connectivity to cortical interneurons. This reduction leads to altered inhibition during bursts of cortical activity. Significance This altered inhibition demonstrates that alterations in cortical circuitry precede the onset of seizures by more than a week.
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Affiliation(s)
- Stephen P Currie
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Liliana L Luz
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Sam A Booker
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - David J A Wyllie
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.,Centre for Brain Development and Repair, InStem, Bangalore, India
| | - Peter C Kind
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.,Centre for Brain Development and Repair, InStem, Bangalore, India
| | - Michael I Daw
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
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Crocker-Buque A, Currie SP, Luz LL, Grant SG, Duffy KR, Kind PC, Daw MI. Altered thalamocortical development in the SAP102 knockout model of intellectual disability. Hum Mol Genet 2016; 25:4052-4061. [PMID: 27466188 PMCID: PMC5291236 DOI: 10.1093/hmg/ddw244] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [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: 05/11/2016] [Revised: 06/24/2016] [Accepted: 07/13/2016] [Indexed: 12/30/2022] Open
Abstract
Genetic mutations known to cause intellectual disabilities (IDs) are concentrated in specific sets of genes including both those encoding synaptic proteins and those expressed during early development. We have characterized the effect of genetic deletion of Dlg3, an ID-related gene encoding the synaptic NMDA-receptor interacting protein synapse-associated protein 102 (SAP102), on development of the mouse somatosensory cortex. SAP102 is the main representative of the PSD-95 family of postsynaptic MAGUK proteins during early development and is proposed to play a role in stabilizing receptors at immature synapses. Genetic deletion of SAP102 caused a reduction in the total number of thalamocortical (TC) axons innervating the somatosensory cortex, but did not affect the segregation of barrels. On a synaptic level SAP102 knockout mice display a transient speeding of NMDA receptor kinetics during the critical period for TC plasticity, despite no reduction in GluN2B-mediated component of synaptic transmission. These data indicated an interesting dissociation between receptor kinetics and NMDA subunit expression. Following the critical period NMDA receptor function was unaffected by loss of SAP102 but there was a reduction in the divergence of TC connectivity. These data suggest that changes in synaptic function early in development caused by mutations in SAP102 result in changes in network connectivity later in life.
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Affiliation(s)
- Alex Crocker-Buque
- Centre for Integrative Physiology and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Stephen P Currie
- Centre for Integrative Physiology and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Liliana L Luz
- Centre for Integrative Physiology and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Seth G Grant
- Centre for Clinical Brain Sciences, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - Kevin R Duffy
- Department of Psychology and Neuroscience, Dalhousie University, 1355 Oxford Street, Halifax, NS B3H 4R2, Canada
| | - Peter C Kind
- Centre for Integrative Physiology and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK .,Centre for Brain Development and Repair, InStem, Bangalore 560065, India
| | - Michael I Daw
- Centre for Integrative Physiology and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
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Abstract
The main input to primary sensory cortex is via thalamocortical (TC) axons that form the greatest number of synapses in layer 4, but also synapse onto neurons in layer 6. The development of the TC input to layer 4 has been widely studied, but less is known about the development of the layer 6 input. Here, we show that, in neonates, the input to layer 6 is as strong as that to layer 4. Throughout the first postnatal week, there is an experience-dependent strengthening specific to layer 4, which correlates with the ability of synapses in layer 4, but not in layer 6, to undergo long-term potentiation (LTP). This strengthening consists of an increase in axon branching and the divergence of connectivity in layer 4 without a change in the strength of individual connections. We propose that experience-driven LTP stabilizes transient TC synapses in layer 4 to increase strength and divergence specifically in layer 4 over layer 6.
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Affiliation(s)
- Alex Crocker-Buque
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - Sarah M Brown
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - Peter C Kind
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - John T R Isaac
- Developmental Synaptic Plasticity Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA Current address: Lilly UK, Erl Wood Manor, Windlesham, UK
| | - Michael I Daw
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
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Daw MI, Ashby MC, Isaac JTR. Coordinated developmental recruitment of latent fast spiking interneurons in layer IV barrel cortex. Nat Neurosci 2007; 10:453-61. [PMID: 17351636 DOI: 10.1038/nn1866] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Accepted: 02/08/2007] [Indexed: 11/09/2022]
Abstract
Feedforward inhibitory GABAergic transmission is critical for mature cortical circuit function; in the neonate, however, GABA is depolarizing and believed to have a different role. Here we show that the GABAA receptor-mediated conductance is depolarizing in excitatory (stellate) cells in neonatal (postnatal day [P]3-5) layer IV barrel cortex, but GABAergic transmission at this age is not engaged by thalamocortical input in the feedforward circuit and has no detectable circuit function. However, recruitment occurs at P6-7 as a result of coordinated increases in thalamic drive to fast-spiking interneurons, fast-spiking interneuron-stellate cell connectivity and hyperpolarization of the GABAA receptor-mediated response. Thus, GABAergic circuits are not engaged by thalamocortical input in the neonate, but are poised for a remarkably coordinated development of feedforward inhibition at the end of the first postnatal week, which has profound effects on circuit function at this critical time in development.
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Affiliation(s)
- Michael I Daw
- Medical Research Council Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, Bristol BS8 1TD, UK
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Daw MI, Scott HL, Isaac JTR. Developmental synaptic plasticity at the thalamocortical input to barrel cortex: mechanisms and roles. Mol Cell Neurosci 2007; 34:493-502. [PMID: 17329121 PMCID: PMC1952688 DOI: 10.1016/j.mcn.2007.01.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Revised: 12/21/2006] [Accepted: 01/03/2007] [Indexed: 11/28/2022] Open
Abstract
The thalamocortical (TC) input to layer IV provides the major pathway for ascending sensory information to the mammalian sensory cortex. During development there is a dramatic refinement of this input that underlies the maturation of the topographical map in layer IV. Over the last 10 years our understanding of the mechanisms of the developmental and experience-driven changes in synaptic function at TC synapses has been greatly advanced. Here we describe these studies that point to a key role for NMDA receptor-dependent synaptic plasticity, a role for kainate receptors and for a rapid maturation in GABAergic inhibition. The expression mechanisms of some of the forms of neonatal synaptic plasticity are novel and, in combination with other mechanisms, produce a layer IV circuit that exhibits functional properties necessary for mature sensory processing.
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Affiliation(s)
- Michael I Daw
- MRC Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, University Walk, Bristol BS8 1TD, UK.
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Abstract
Developing neuronal networks acquire the ability to precisely time events, a key feature required for information processing. In the barrel cortex, encoding of information requires a high-precision temporal code with a resolution of approximately 5 ms; however, it is not known what process drives the maturation in timing precision. Here, we report that long-term potentiation (LTP) at thalamocortical synapses in the neonatal layer IV barrel cortex produces a dramatic improvement in the timing of neuronal output and synaptic input. LTP strongly reduces the latency and variability of synaptically evoked action potentials, improving the fidelity of timing to within that predicted to be required for adult sensory processing. Such changes in timing also occur during development in the neonate. LTP also reduces the summation of EPSPs shortening the window for coincidence detection for synaptic input. In contrast to these reliable effects, LTP produced only a modest and variable change in synaptic efficacy. Thus, our findings suggest that the primary role of this form of neonatal LTP is for the acquisition of timing precision and the refinement of coincidence detection, rather than an increase in synaptic strength. Therefore, neonatal thalamocortical LTP may be a critical prerequisite for the maturation of information processing in the barrel cortex.
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Daw MI, Bortolotto ZA, Saulle E, Zaman S, Collingridge GL, Isaac JTR. Phosphatidylinositol 3 kinase regulates synapse specificity of hippocampal long-term depression. Nat Neurosci 2002; 5:835-6. [PMID: 12161757 DOI: 10.1038/nn903] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [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]
Abstract
To investigate the role of phosphatidylinositol 3 kinase (PI3 kinase) in hippocampal synaptic plasticity, we used whole-cell patch clamp recordings from rat CA1 neurons to determine the effects of PI3 kinase inhibitors on long-term depression (LTD). PI3 kinase blockade caused a loss of synapse specificity of LTD that was dependent on the co-activation of NMDA-type glutamate receptors (NMDARs) and metabotropic glutamate receptors (mGluRs), and involved release of Ca(2+) from intracellular stores. These findings suggest that the synapse specificity of hippocampal LTD may not be an intrinsic property of this form of homosynaptic plasticity, but rather that it can be regulated by PI3 kinase.
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Affiliation(s)
- Michael I Daw
- MRC Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, University Walk, Bristol BS8 1TD, UK
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Daw MI, Chittajallu R, Bortolotto ZA, Dev KK, Duprat F, Henley JM, Collingridge GL, Isaac JT. PDZ proteins interacting with C-terminal GluR2/3 are involved in a PKC-dependent regulation of AMPA receptors at hippocampal synapses. Neuron 2000; 28:873-86. [PMID: 11163273 DOI: 10.1016/s0896-6273(00)00160-4] [Citation(s) in RCA: 274] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We investigated the role of PDZ proteins (GRIP, ABP, and PICK1) interacting with the C-terminal GluR2 by infusing a ct-GluR2 peptide ("pep2-SVKI") into CA1 pyramidal neurons in hippocampal slices using whole-cell recordings. Pep2-SVKI, but not a control or PICK1 selective peptide, caused AMPAR-mediated EPSC amplitude to increase in approximately one-third of control neurons and in most neurons following the prior induction of LTD. Pep2-SVKI also blocked LTD; however, this occurred in all neurons. A PKC inhibitor prevented these effects of pep2-SVKI on synaptic transmission and LTD. We propose a model in which the maintenance of LTD involves the binding of AMPARs to PDZ proteins to prevent their reinsertion. We also present evidence that PKC regulates AMPAR reinsertion during dedepression.
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Affiliation(s)
- M I Daw
- MRC Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, University Walk, BS8 1TD, Bristol, United Kingdom
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