The Experts below are selected from a list of 4854 Experts worldwide ranked by ideXlab platform
Peter F Hitchcock - One of the best experts on this subject based on the ideXlab platform.
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dynamic expression of the basic helix loop helix transcription factor NeuroD in the rod and cone photoreceptor lineages in the retina of the embryonic and larval zebrafish
The Journal of Comparative Neurology, 2007Co-Authors: Peter F Hitchcock, Margaret J OchocinskaAbstract:NeuroD is a basic helix-loop-helix (bHLH) transcription factor critical for determining neuronal cell fate and regulating withdrawal from the cell cycle. We showed previously that, in goldfish, NeuroD is expressed in the rod photoreceptor lineage, and we inferred that NeuroD is also expressed in a subset of amacrine cells and nascent cone photoreceptors. Here we extended that study by examining the temporal and spatial expression pattern of NeuroD in the embryonic and larval zebrafish and by identifying the cell types that express this gene. NeuroD expression in the developing zebrafish retina is dynamic, spanning early retinogenesis and the maturation of cone photoreceptors. In early retinogenesis NeuroD expression expands from a small patch in the ventronasal retina, through the remaining retinal neuroepithelium. As retinogenesis progresses, NeuroD expression becomes restricted to amacrine cells, immature cones, and cells of rod and cone lineages. This expression achieves an adult pattern by 96 hours postfertilization (hpf), whereupon the temporal pattern of NeuroD expression in central retina is spatially recapitulated at the germinative margin. The cellular pattern of expression suggests that NeuroD regulates aspects of rod and cone genesis, but through separate cellular lineages. Furthermore, NeuroD is coexpressed with the cone-rodhomeobox transcription factor (Crx) in putative cone progenitors and nascent cone photoreceptors, suggesting that, in the zebrafish retina, as in other vertebrate retinas, similar genetic cascades regulate photoreceptor genesis and maturation. J. Comp. Neurol. 501:1–12, 2007. © 2007 Wiley-Liss, Inc. Indexing terms: neurogenesis; development; gene expression; photoreceptors
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the basic helix loop helix transcription factor NeuroD is expressed in the rod lineage of the teleost retina
The Journal of Comparative Neurology, 2004Co-Authors: Peter F Hitchcock, Laura KakukatkinsAbstract:Persistent rod genesis in the retinas of teleost fish was first described over 2 decades ago, but little is known regarding the underlying genetic and molecular mechanisms that govern this phenomenon. Because of its function in the developing mammalian retina and persistently mitotic adult tissues, we sought to characterize the cellular expression of the basic helix-loop-helix (bHLH) transcription factor NeuroD in the persistently neurogenic retina of adult teleosts. We show here that, in the adult retina of the goldfish, NeuroD is expressed by putative amacrine cells, nascent cones, and the mitotically active cells of the rod lineage. NeuroD is the first gene shown to be expressed by rod precursors, the immediate antecedents of rod photoreceptors. In contrast to the vertebrate classes described previously, NeuroD is not expressed in multipotent progenitors in the teleost retina. Combining NeuroD in situ hybridizations with cell-cycle-specific markers suggests that, in rod precursors, NeuroD expression is cell cycle specific. J. Comp. Neurol. 477:108 –117, 2004. © 2004 Wiley-Liss, Inc.
Patrik Brundin - One of the best experts on this subject based on the ideXlab platform.
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the origin development and molecular diversity of rodent olfactory bulb glutamatergic neurons distinguished by expression of transcription factor NeuroD1
PLOS ONE, 2015Co-Authors: Laurent Roybon, Simon R.w. Stott, Patrik Brundin, Teresa L Mastracci, Joyce Li, Andrew B Leiter, Lori Sussel, Jiayi LiAbstract:Production of olfactory bulb neurons occurs continuously in the rodent brain. Little is known, however, about cellular diversity in the glutamatergic neuron subpopulation. In the central nervous system, the basic helix-loop-helix transcription factor NeuroD1 (ND1) is commonly associated with glutamatergic neuron development. In this study, we utilized ND1 to identify the different subpopulations of olfactory bulb glutamategic neurons and their progenitors, both in the embryo and postnatally. Using knock-in mice, transgenic mice and retroviral transgene delivery, we demonstrate the existence of several different populations of glutamatergic olfactory bulb neurons, the progenitors of which are ND1+ and ND1- lineage-restricted, and are temporally and regionally separated. We show that the first olfactory bulb glutamatergic neurons produced – the mitral cells – can be divided into molecularly diverse subpopulations. Our findings illustrate the complexity of neuronal diversity in the olfactory bulb and that seemingly homogenous neuronal populations can consist of multiple subpopulations with unique molecular signatures of transcription factors and expressing neuronal subtype-specific markers.
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gabaergic differentiation induced by mash1 is compromised by the bhlh proteins neurogenin2 NeuroD1 and NeuroD2
Cerebral Cortex, 2010Co-Authors: Laurent Roybon, Diogo Ribeiro, Patrik BrundinAbstract:During forebrain development, Mash1 directs gamma-aminobutyric acid (GABA)ergic neuron differentiation ventrally in the ganglionic eminences. Repression of Mash1 in the cortex is necessary to prevent the formation of GABAergic interneurons. Negative regulation of Mash1 has been attributed to members of the Neurogenin family; the genetic ablation of Neurogenin2 (Ngn2) leads to the derepression of Mash1 and the formation of ectopic GABAergic neurons in the cortex. We have developed an in vitro system to clarify the importance of NeuroD proteins in the Mash1 regulatory pathway. Using a neurosphere culture system, we show that the downstream effectors of the Ngn2 pathway NeuroD1 and NeuroD2 can abrogate GABAergic differentiation directed by Mash1. The ectopic expression of either of these genes in Mash1-expressing cells derived from the lateral ganglionic eminence, independently downregulate Mash1 expression without affecting expression of distal less homeodomain genes. This results in a complete loss of the GABAergic phenotype. Moreover, we demonstrate that ectopic expression of Mash1 in cortical progenitors is sufficient to phenocopy the loss of Ngn2 and strongly enhances ectopic GABAergic differentiation. Collectively, our results define the compensatory and cross-regulatory mechanisms that exist among basic helix-loop-helix transcription factors during neuronal fate specification.
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neurogenin2 directs granule neuroblast production and amplification while NeuroD1 specifies neuronal fate during hippocampal neurogenesis
PLOS ONE, 2009Co-Authors: Laurent Roybon, Simon R.w. Stott, François Guillemot, Jiayi Li, Tord A Hjalt, Patrik BrundinAbstract:The specification and differentiation of dentate gyrus granule neurons in the hippocampus require temporally and spatially coordinated actions of both intrinsic and extrinsic molecules. The basic helix-loop-helix transcription factor Neurogenin2 (Ngn2) and NeuroD1 are key regulators in these processes. Based on existing classification, we analyzed the molecular events occurring during hippocampal neurogenesis, primarily focusing on juvenile animals. We found that Ngn2 is transiently expressed by late type-2a amplifying progenitors. The Ngn2 progenies mature into hippocampal granule neurons. Interestingly, the loss of Ngn2 at early stages of development leads to a robust reduction in neurogenesis, but does not disturb granule neuron maturation per se. We found that the role of Ngn2 is to maintain progenitors in an undifferentiated state, allowing them to amplify prior to their maturation into granule neurons upon NeuroD1 induction. When we overexpressed Ngn2 and NeuroD1 in vivo, we found NeuroD1 to exhibit a more pronounced neuron-inductive effect, leading to granule neuron commitment, than that displayed by Ngn2. Finally, we observed that all markers expressed during the transcriptional control of hippocampal neurogenesis in rodents are also present in the human hippocampus. Taken together, we demonstrate a critical role of for Ngn2 and NeuroD1 in controlling neuronal commitment and hippocampal granule neuroblast formation, both during embryonic development and in post-natal hippocampal granule neurogenesis.
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Involvement of Ngn2, Tbr and NeuroD proteins during postnatal olfactory bulb neurogenesis
The European journal of neuroscience, 2009Co-Authors: Laurent Roybon, Tomas Deierborg, Patrik BrundinAbstract:Postnatal neurogenesis takes place in two brain regions, the hippocampus and the subventricular zone (SVZ). The transcriptional cascade controlling hippocampal neurogenesis has been described in detail; however, the transcriptional control of olfactory bulb neurogenesis is still not well mapped. In this study, we provide insights into the molecular events controlling postnatal olfactory bulb neurogenesis. We first show the existence of diverse neural stem cell/progenitor populations along the SVZ-rostral migratory stream (RMS) axis, focusing on those expressing the basic helix-loop-helix (bHLH) transcription factor Mash1. We provide evidence that Mash1-derived progenies generate oligodendrocytic and neuronal precursors through the transient expression of the bHLH transcription factors Olig2 and neurogenin2 (Ngn2), respectively. Furthermore, we reveal that Ngn2-positive progenies express the T-box transcription factors Tbr2 and Tbr1, which are usually present during cortical and hippocampal glutamatergic neuronal differentiation. We also highlight a cell population expressing another bHLH transcription factor, NeuroD1 (ND1). The ND1-positive cells are located in the SVZ-RMS axis and also co-express Tbr2, Tbr1 and NeuroD2. The observations that these cells incorporate bromodeoxyuridine and express both doublecortin and polysialylated form of neural cell adhesion molecule suggest that they are newborn neurons. Finally, using an in vitro assay, we demonstrate that Ngn2 and ND1 equally and exclusively direct differentiation of Mash1-expressing precursors into calbindin-expressing and calretinin-expressing neurons, which are both neuronal subtypes normally found in the olfactory bulb. Taken together, our data illustrate that Ngn2, NeuroD and Tbr transcription factors are involved in postnatal neurogenesis in the olfactory bulb.
Yuchen Chen - One of the best experts on this subject based on the ideXlab platform.
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development of neuroregenerative gene therapy to reverse glial scar tissue back to neuron enriched tissue
Frontiers in Cellular Neuroscience, 2020Co-Authors: Lei Zhang, Yuchen Chen, Fengyu Zhang, Zhuofan Lei, Ziyuan Guo, Zifei Pei, Alice Cai, Gabriel Mok, Grace Lee, Vishal SwaminathanAbstract:Nerve injury often causes neuronal loss and glial scar formation. We have recently demonstrated NeuroD1-mediated direct conversion of reactive glial cells into functional neurons in adult mouse brains. Here, we further investigate whether such direct glia-to-neuron conversion technology can reverse glial scar back to neural tissue in a severe stab injury model of the mouse cortex. Using adeno-associated virus (AAV)-based gene therapy approach, we ectopically expressed single neural transcription factor NeuroD1 in reactive astrocytes in the injured areas.We discovered that the reactive astrocytes were efficiently converted into neurons both before and after glial scar formation, and the remaining astrocytes proliferated to repopulate themselves.The astrocyte-converted neurons were highly functional, capable of firing action potentials and establishing synaptic connections with other neurons. Unexpectedly, expression of NeuroD1 in reactive astrocytes resulted in a significant reduction of toxic A1 astrocytes, together with a significant decrease of reactive microglia and neuroinflammation. Furthermore, accompanying the regeneration of new neurons and repopulation of new astrocytes, new blood vessels emerged and blood-brain-barrier was restored. These results demonstrate an innovative neuroregenerative gene therapy that can directly reverse glial scar back to neural tissue, opening a new avenue for brain repair after injury.• Glial scar can be reversed back to neural tissue through neuroregenerative gene therapy• Astrocytes are not depleted after neuronal conversion• Neuron to glia ratio after injury can be rebalanced through in vivo cell conversion• Conversion of reactive astrocytes into neurons reduces neuroinflammation• Astrocyte-to-neuron conversion restores blood vessels and blood-brain-barrierBrain repair, brain injury, NeuroD1, astrocyte-to-neuron conversion, in vivo reprogramming, neuron to astrocyte ratio, neuroinflammation, blood-brain-barrier
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gene therapy conversion of striatal astrocytes into gabaergic neurons in mouse models of huntington s disease
Nature Communications, 2020Co-Authors: Matthew Parry, Yuchen Chen, Ziyuan Guo, Zifei Pei, Min Hui Liu, Xiao Yi Hou, Hui Wang, Rachel Cain, Sambangi AbhijeetAbstract:Huntington's disease (HD) is caused by Huntingtin (Htt) gene mutation resulting in the loss of striatal GABAergic neurons and motor functional deficits. We report here an in vivo cell conversion technology to reprogram striatal astrocytes into GABAergic neurons in both R6/2 and YAC128 HD mouse models through AAV-mediated ectopic expression of NeuroD1 and Dlx2 transcription factors. We found that the astrocyte-to-neuron (AtN) conversion rate reached 80% in the striatum and >50% of the converted neurons were DARPP32+ medium spiny neurons. The striatal astrocyte-converted neurons showed action potentials and synaptic events, and projected their axons to the targeted globus pallidus and substantia nigra in a time-dependent manner. Behavioral analyses found that NeuroD1 and Dlx2-treated R6/2 mice showed a significant extension of life span and improvement of motor functions. This study demonstrates that in vivo AtN conversion may be a disease-modifying gene therapy to treat HD and other NeuroDegenerative disorders.
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a NeuroD1 aav based gene therapy for functional brain repair after ischemic injury through in vivo astrocyte to neuron conversion
Molecular Therapy, 2020Co-Authors: Yuchen Chen, Zifei Pei, Grace Lee, Ning Xin, Fabricio H Domonte, Susan Keefe, Emma Yellin, Miranda Chen, Jiuchao Yin, Angelica MiniertoribioAbstract:Adult mammalian brains have largely lost neuroregeneration capability except for a few niches. Previous studies have converted glial cells into neurons, but the total number of neurons generated is limited and the therapeutic potential is unclear. Here, we demonstrate that NeuroD1-mediated in situ astrocyte-to-neuron conversion can regenerate a large number of functional new neurons after ischemic injury. Specifically, using NeuroD1 adeno-associated virus (AAV)-based gene therapy, we were able to regenerate one third of the total lost neurons caused by ischemic injury and simultaneously protect another one third of injured neurons, leading to a significant neuronal recovery. RNA sequencing and immunostaining confirmed neuronal recovery after cell conversion at both the mRNA level and protein level. Brain slice recordings found that the astrocyte-converted neurons showed robust action potentials and synaptic responses at 2 months after NeuroD1 expression. Anterograde and retrograde tracing revealed long-range axonal projections from astrocyte-converted neurons to their target regions in a time-dependent manner. Behavioral analyses showed a significant improvement of both motor and cognitive functions after cell conversion. Together, these results demonstrate that in vivo cell conversion technology through NeuroD1-based gene therapy can regenerate a large number of functional new neurons to restore lost neuronal functions after injury.
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reversing glial scar back to neural tissue through NeuroD1 mediated astrocyte to neuron conversion
bioRxiv, 2018Co-Authors: Lei Zhang, Yuchen Chen, Fengyu Zhang, Vishal Swaminathan, Fan Wang, Gong ChenAbstract:Nerve injury often causes neuronal loss and glial proliferation, disrupting the delicate balance between neurons and glial cells in the brain. Recently, we have developed an innovative technology to convert internal reactive glial cells into functional neurons inside the mouse brain. Here, we further demonstrate that such glia-to-neuron conversion can rebalance neuron-glia ratio and reverse glial scar back to neural tissue. Specifically, using a severe stab injury model in the mouse cortex, we demonstrated that ectopic expression of NeuroD1 in reactive astrocytes significantly reduced glial reactivity and transformed toxic A1 astrocytes into less harmful astrocytes before neuronal conversion. Importantly, astrocytes were not depleted after neuronal conversion but rather repopulated due to its intrinsic proliferation capability. Remarkably, converting reactive astrocytes into neurons also significantly reduced microglia-mediated neuroinflammation. Moreover, accompanying regeneration of new neurons together with repopulation of new astrocytes, blood-brain-barrier was restored and synaptic density was rescued in the injury sites. Together, these results demonstrate that glial scar can be reversed back to neural tissue through rebalancing neuron:glia ratio after glia-to-neuron conversion.
Laurent Roybon - One of the best experts on this subject based on the ideXlab platform.
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the origin development and molecular diversity of rodent olfactory bulb glutamatergic neurons distinguished by expression of transcription factor NeuroD1
PLOS ONE, 2015Co-Authors: Laurent Roybon, Simon R.w. Stott, Patrik Brundin, Teresa L Mastracci, Joyce Li, Andrew B Leiter, Lori Sussel, Jiayi LiAbstract:Production of olfactory bulb neurons occurs continuously in the rodent brain. Little is known, however, about cellular diversity in the glutamatergic neuron subpopulation. In the central nervous system, the basic helix-loop-helix transcription factor NeuroD1 (ND1) is commonly associated with glutamatergic neuron development. In this study, we utilized ND1 to identify the different subpopulations of olfactory bulb glutamategic neurons and their progenitors, both in the embryo and postnatally. Using knock-in mice, transgenic mice and retroviral transgene delivery, we demonstrate the existence of several different populations of glutamatergic olfactory bulb neurons, the progenitors of which are ND1+ and ND1- lineage-restricted, and are temporally and regionally separated. We show that the first olfactory bulb glutamatergic neurons produced – the mitral cells – can be divided into molecularly diverse subpopulations. Our findings illustrate the complexity of neuronal diversity in the olfactory bulb and that seemingly homogenous neuronal populations can consist of multiple subpopulations with unique molecular signatures of transcription factors and expressing neuronal subtype-specific markers.
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gabaergic differentiation induced by mash1 is compromised by the bhlh proteins neurogenin2 NeuroD1 and NeuroD2
Cerebral Cortex, 2010Co-Authors: Laurent Roybon, Diogo Ribeiro, Patrik BrundinAbstract:During forebrain development, Mash1 directs gamma-aminobutyric acid (GABA)ergic neuron differentiation ventrally in the ganglionic eminences. Repression of Mash1 in the cortex is necessary to prevent the formation of GABAergic interneurons. Negative regulation of Mash1 has been attributed to members of the Neurogenin family; the genetic ablation of Neurogenin2 (Ngn2) leads to the derepression of Mash1 and the formation of ectopic GABAergic neurons in the cortex. We have developed an in vitro system to clarify the importance of NeuroD proteins in the Mash1 regulatory pathway. Using a neurosphere culture system, we show that the downstream effectors of the Ngn2 pathway NeuroD1 and NeuroD2 can abrogate GABAergic differentiation directed by Mash1. The ectopic expression of either of these genes in Mash1-expressing cells derived from the lateral ganglionic eminence, independently downregulate Mash1 expression without affecting expression of distal less homeodomain genes. This results in a complete loss of the GABAergic phenotype. Moreover, we demonstrate that ectopic expression of Mash1 in cortical progenitors is sufficient to phenocopy the loss of Ngn2 and strongly enhances ectopic GABAergic differentiation. Collectively, our results define the compensatory and cross-regulatory mechanisms that exist among basic helix-loop-helix transcription factors during neuronal fate specification.
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neurogenin2 directs granule neuroblast production and amplification while NeuroD1 specifies neuronal fate during hippocampal neurogenesis
PLOS ONE, 2009Co-Authors: Laurent Roybon, Simon R.w. Stott, François Guillemot, Jiayi Li, Tord A Hjalt, Patrik BrundinAbstract:The specification and differentiation of dentate gyrus granule neurons in the hippocampus require temporally and spatially coordinated actions of both intrinsic and extrinsic molecules. The basic helix-loop-helix transcription factor Neurogenin2 (Ngn2) and NeuroD1 are key regulators in these processes. Based on existing classification, we analyzed the molecular events occurring during hippocampal neurogenesis, primarily focusing on juvenile animals. We found that Ngn2 is transiently expressed by late type-2a amplifying progenitors. The Ngn2 progenies mature into hippocampal granule neurons. Interestingly, the loss of Ngn2 at early stages of development leads to a robust reduction in neurogenesis, but does not disturb granule neuron maturation per se. We found that the role of Ngn2 is to maintain progenitors in an undifferentiated state, allowing them to amplify prior to their maturation into granule neurons upon NeuroD1 induction. When we overexpressed Ngn2 and NeuroD1 in vivo, we found NeuroD1 to exhibit a more pronounced neuron-inductive effect, leading to granule neuron commitment, than that displayed by Ngn2. Finally, we observed that all markers expressed during the transcriptional control of hippocampal neurogenesis in rodents are also present in the human hippocampus. Taken together, we demonstrate a critical role of for Ngn2 and NeuroD1 in controlling neuronal commitment and hippocampal granule neuroblast formation, both during embryonic development and in post-natal hippocampal granule neurogenesis.
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Involvement of Ngn2, Tbr and NeuroD proteins during postnatal olfactory bulb neurogenesis
The European journal of neuroscience, 2009Co-Authors: Laurent Roybon, Tomas Deierborg, Patrik BrundinAbstract:Postnatal neurogenesis takes place in two brain regions, the hippocampus and the subventricular zone (SVZ). The transcriptional cascade controlling hippocampal neurogenesis has been described in detail; however, the transcriptional control of olfactory bulb neurogenesis is still not well mapped. In this study, we provide insights into the molecular events controlling postnatal olfactory bulb neurogenesis. We first show the existence of diverse neural stem cell/progenitor populations along the SVZ-rostral migratory stream (RMS) axis, focusing on those expressing the basic helix-loop-helix (bHLH) transcription factor Mash1. We provide evidence that Mash1-derived progenies generate oligodendrocytic and neuronal precursors through the transient expression of the bHLH transcription factors Olig2 and neurogenin2 (Ngn2), respectively. Furthermore, we reveal that Ngn2-positive progenies express the T-box transcription factors Tbr2 and Tbr1, which are usually present during cortical and hippocampal glutamatergic neuronal differentiation. We also highlight a cell population expressing another bHLH transcription factor, NeuroD1 (ND1). The ND1-positive cells are located in the SVZ-RMS axis and also co-express Tbr2, Tbr1 and NeuroD2. The observations that these cells incorporate bromodeoxyuridine and express both doublecortin and polysialylated form of neural cell adhesion molecule suggest that they are newborn neurons. Finally, using an in vitro assay, we demonstrate that Ngn2 and ND1 equally and exclusively direct differentiation of Mash1-expressing precursors into calbindin-expressing and calretinin-expressing neurons, which are both neuronal subtypes normally found in the olfactory bulb. Taken together, our data illustrate that Ngn2, NeuroD and Tbr transcription factors are involved in postnatal neurogenesis in the olfactory bulb.
Zifei Pei - One of the best experts on this subject based on the ideXlab platform.
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development of neuroregenerative gene therapy to reverse glial scar tissue back to neuron enriched tissue
Frontiers in Cellular Neuroscience, 2020Co-Authors: Lei Zhang, Yuchen Chen, Fengyu Zhang, Zhuofan Lei, Ziyuan Guo, Zifei Pei, Alice Cai, Gabriel Mok, Grace Lee, Vishal SwaminathanAbstract:Nerve injury often causes neuronal loss and glial scar formation. We have recently demonstrated NeuroD1-mediated direct conversion of reactive glial cells into functional neurons in adult mouse brains. Here, we further investigate whether such direct glia-to-neuron conversion technology can reverse glial scar back to neural tissue in a severe stab injury model of the mouse cortex. Using adeno-associated virus (AAV)-based gene therapy approach, we ectopically expressed single neural transcription factor NeuroD1 in reactive astrocytes in the injured areas.We discovered that the reactive astrocytes were efficiently converted into neurons both before and after glial scar formation, and the remaining astrocytes proliferated to repopulate themselves.The astrocyte-converted neurons were highly functional, capable of firing action potentials and establishing synaptic connections with other neurons. Unexpectedly, expression of NeuroD1 in reactive astrocytes resulted in a significant reduction of toxic A1 astrocytes, together with a significant decrease of reactive microglia and neuroinflammation. Furthermore, accompanying the regeneration of new neurons and repopulation of new astrocytes, new blood vessels emerged and blood-brain-barrier was restored. These results demonstrate an innovative neuroregenerative gene therapy that can directly reverse glial scar back to neural tissue, opening a new avenue for brain repair after injury.• Glial scar can be reversed back to neural tissue through neuroregenerative gene therapy• Astrocytes are not depleted after neuronal conversion• Neuron to glia ratio after injury can be rebalanced through in vivo cell conversion• Conversion of reactive astrocytes into neurons reduces neuroinflammation• Astrocyte-to-neuron conversion restores blood vessels and blood-brain-barrierBrain repair, brain injury, NeuroD1, astrocyte-to-neuron conversion, in vivo reprogramming, neuron to astrocyte ratio, neuroinflammation, blood-brain-barrier
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gene therapy conversion of striatal astrocytes into gabaergic neurons in mouse models of huntington s disease
Nature Communications, 2020Co-Authors: Matthew Parry, Yuchen Chen, Ziyuan Guo, Zifei Pei, Min Hui Liu, Xiao Yi Hou, Hui Wang, Rachel Cain, Sambangi AbhijeetAbstract:Huntington's disease (HD) is caused by Huntingtin (Htt) gene mutation resulting in the loss of striatal GABAergic neurons and motor functional deficits. We report here an in vivo cell conversion technology to reprogram striatal astrocytes into GABAergic neurons in both R6/2 and YAC128 HD mouse models through AAV-mediated ectopic expression of NeuroD1 and Dlx2 transcription factors. We found that the astrocyte-to-neuron (AtN) conversion rate reached 80% in the striatum and >50% of the converted neurons were DARPP32+ medium spiny neurons. The striatal astrocyte-converted neurons showed action potentials and synaptic events, and projected their axons to the targeted globus pallidus and substantia nigra in a time-dependent manner. Behavioral analyses found that NeuroD1 and Dlx2-treated R6/2 mice showed a significant extension of life span and improvement of motor functions. This study demonstrates that in vivo AtN conversion may be a disease-modifying gene therapy to treat HD and other NeuroDegenerative disorders.
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a NeuroD1 aav based gene therapy for functional brain repair after ischemic injury through in vivo astrocyte to neuron conversion
Molecular Therapy, 2020Co-Authors: Yuchen Chen, Zifei Pei, Grace Lee, Ning Xin, Fabricio H Domonte, Susan Keefe, Emma Yellin, Miranda Chen, Jiuchao Yin, Angelica MiniertoribioAbstract:Adult mammalian brains have largely lost neuroregeneration capability except for a few niches. Previous studies have converted glial cells into neurons, but the total number of neurons generated is limited and the therapeutic potential is unclear. Here, we demonstrate that NeuroD1-mediated in situ astrocyte-to-neuron conversion can regenerate a large number of functional new neurons after ischemic injury. Specifically, using NeuroD1 adeno-associated virus (AAV)-based gene therapy, we were able to regenerate one third of the total lost neurons caused by ischemic injury and simultaneously protect another one third of injured neurons, leading to a significant neuronal recovery. RNA sequencing and immunostaining confirmed neuronal recovery after cell conversion at both the mRNA level and protein level. Brain slice recordings found that the astrocyte-converted neurons showed robust action potentials and synaptic responses at 2 months after NeuroD1 expression. Anterograde and retrograde tracing revealed long-range axonal projections from astrocyte-converted neurons to their target regions in a time-dependent manner. Behavioral analyses showed a significant improvement of both motor and cognitive functions after cell conversion. Together, these results demonstrate that in vivo cell conversion technology through NeuroD1-based gene therapy can regenerate a large number of functional new neurons to restore lost neuronal functions after injury.