Publications by authors named "Zhen-Ge Luo"

35 Publications

TBC1D3 promotes neural progenitor proliferation by suppressing the histone methyltransferase G9a.

Sci Adv 2021 Jan 15;7(3). Epub 2021 Jan 15.

School of Life Science and Technology, ShanghaiTech University, 201210 Shanghai, China.

Genomic changes during human linage evolution contribute to the expansion of the cerebral cortex to allow more advanced thought processes. The hominoid-specific gene displays robust capacity of promoting the generation and proliferation of neural progenitors (NPs), which are thought to contribute to cortical expansion. However, the underlying mechanisms remain unclear. Here, we found that TBC1D3 interacts with G9a, a euchromatic histone lysine -methyltransferase, which mediates dimethylation of histone 3 in lysine 9 (H3K9me2), a suppressive mark for gene expression. TBC1D3 displayed an inhibitory role in G9a's histone methyltransferase activity. Treatment with G9a inhibitor markedly increased NP proliferation and promoted human cerebral organoid expansion, mimicking the effects caused by TBC1D3 up-regulation. By contrast, blockade of TBC1D3/G9a interaction to disinhibit G9a caused up-regulation of H3K9me2, suppressed NP proliferation, and impaired organoid development. Together, this study has demonstrated a mechanism underlying the role of a hominoid-specific gene in promoting cortical expansion.
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http://dx.doi.org/10.1126/sciadv.aba8053DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7810367PMC
January 2021

Heterogeneous nuclear ribonucleoprotein A3 controls mitotic progression of neural progenitors via interaction with cohesin.

Development 2020 05 15;147(10). Epub 2020 May 15.

School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China

Cortex development is controlled by temporal patterning of neural progenitor (NP) competence with sequential generation of deep and superficial layer neurons, but underlying mechanisms remain elusive. Here, we report a role for heterogeneous nuclear ribonucleoprotein A3 (HNRNPA3) in regulating the division of early cortical NPs that mainly give rise to deep-layer neurons via direct neurogenesis. HNRNPA3 is expressed at high levels in NPs of mouse and human cortex at early stages, with a unique peri-chromosome pattern. Intriguingly, downregulation of HNRNPA3 caused chromosome disarrangement, which hindered normal separation of chromosomes during NP division, leading to mitotic delay. Furthermore, HNRNPA3 is associated with the cohesin-core subunit SMC1A and controls its association with chromosomes, implicating a mechanism for the role of HNRNPA3 in regulating chromosome segregation in dividing NPs. -deficient mice exhibited reduced cortical thickness, especially of deep layers. Moreover, downregulation of HNRNPA3 in cultured human cerebral organoids led to marked reduction in NPs and deep-layer neurons. Thus, this study has identified a crucial role for HNRNPA3 in NP division and highlighted the relationship between mitosis progression and early neurogenesis.
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http://dx.doi.org/10.1242/dev.185132DOI Listing
May 2020

Single-Cell RNA Sequencing Reveals Cell-Type-Specific Mechanisms of Neurological Diseases.

Neurosci Bull 2020 07 15;36(7):821-824. Epub 2020 Apr 15.

School of Life Science and Technology, ShanghaiTech University, Shanghai, 200031, China.

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http://dx.doi.org/10.1007/s12264-020-00496-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7340688PMC
July 2020

Tumor necrosis factor alpha mediates neuromuscular synapse elimination.

Cell Discov 2020 3;6. Epub 2020 Mar 3.

1School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210 China.

During the development of mammalian neuromuscular junction (NMJ), the original supernumerary axon inputs are gradually eliminated, finally leaving each muscle fiber innervated by a single axon terminal. However, the molecular cues that mediate the elimination of redundant axon inputs remain unclear. Here we show that tumor necrosis factor-α (TNFα) expressed in postsynaptic muscle cells plays an important role in presynaptic axonal elimination at the NMJ. We found that intramuscular injection of TNFα into the levator auris longus (LAL) muscles caused disassociation of presynaptic nerve terminals from the postsynaptic acetylcholine receptor (AChR) clusters. By contrast, genetic ablation of TNFα globally or specifically in skeletal muscle cells, but not in motoneurons or Schwann cells, delayed the synaptic elimination. Moreover, ablation of TNFα in muscle cells attenuated the tendency of activity-dependent competition in a motoneuron-muscle coculture system. These results suggest a role of postsynaptic TNFα in the elimination of redundant synaptic inputs.
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http://dx.doi.org/10.1038/s41421-020-0143-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7051980PMC
March 2020

Single-cell transcriptomes reveal molecular specializations of neuronal cell types in the developing cerebellum.

J Mol Cell Biol 2019 08;11(8):636-648

Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China.

The cerebellum is critical for controlling motor and non-motor functions via cerebellar circuit that is composed of defined cell types, which approximately account for more than half of neurons in mammals. The molecular mechanisms controlling developmental progression and maturation processes of various cerebellar cell types need systematic investigation. Here, we analyzed transcriptome profiles of 21119 single cells of the postnatal mouse cerebellum and identified eight main cell clusters. Functional annotation of differentially expressed genes revealed trajectory hierarchies of granule cells (GCs) at various states and implied roles of mitochondrion and ATPases in the maturation of Purkinje cells (PCs), the sole output cells of the cerebellar cortex. Furthermore, we analyzed gene expression patterns and co-expression networks of 28 ataxia risk genes, and found that most of them are related with biological process of mitochondrion and around half of them are enriched in PCs. Our results also suggested core transcription factors that are correlated with interneuron differentiation and characteristics for the expression of secretory proteins in glia cells, which may participate in neuronal modulation. Thus, this study presents a systematic landscape of cerebellar gene expression in defined cell types and a general gene expression framework for cerebellar development and dysfunction.
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http://dx.doi.org/10.1093/jmcb/mjy089DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6788728PMC
August 2019

[Molecular and cellular mechanisms of cortical expansion and folding in brain development and evolution].

Sheng Li Xue Bao 2017 Aug;69(4):485-497

Institute of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.

During the evolution from primates to humans, the size of cerebral cortex is increased by forming more gyri and sulci, which is believed to be highly associated with cognitive abilities and the basis of higher brain functions in humans. Accumulating lines of evidence have shown that the cortical size is regulated both by protein-coding genes and non-coding RNAs. In particular, the recently identified outer radial glial cells (oRGs) distributed in the outer subventricular zone (oSVZ) of gyrencephalic brains, have been considered to be important for cortical expansion and folding. This review summarizes recent progresses in the understanding of cortex expansion and discusses the potential molecular and cellular mechanisms of cortical folding.
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August 2017

Autophagy induction stabilizes microtubules and promotes axon regeneration after spinal cord injury.

Proc Natl Acad Sci U S A 2016 10 16;113(40):11324-11329. Epub 2016 Sep 16.

Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China; Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China

Remodeling of cytoskeleton structures, such as microtubule assembly, is believed to be crucial for growth cone initiation and regrowth of injured axons. Autophagy plays important roles in maintaining cellular homoeostasis, and its dysfunction causes neuronal degeneration. The role of autophagy in axon regeneration after injury remains speculative. Here we demonstrate a role of autophagy in regulating microtubule dynamics and axon regeneration. We found that autophagy induction promoted neurite outgrowth, attenuated the inhibitory effects of nonpermissive substrate myelin, and decreased the formation of retraction bulbs following axonal injury in cultured cortical neurons. Interestingly, autophagy induction stabilized microtubules by degrading SCG10, a microtubule disassembly protein in neurons. In mice with spinal cord injury, local administration of a specific autophagy-inducing peptide, Tat-beclin1, to lesion sites markedly attenuated axonal retraction of spinal dorsal column axons and cortical spinal tract and promoted regeneration of descending axons following long-term observation. Finally, administration of Tat-beclin1 improved the recovery of motor behaviors of injured mice. These results show a promising effect of an autophagy-inducing reagent on injured axons, providing direct evidence supporting a beneficial role of autophagy in axon regeneration.
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http://dx.doi.org/10.1073/pnas.1611282113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5056063PMC
October 2016

The hominoid-specific gene TBC1D3 promotes generation of basal neural progenitors and induces cortical folding in mice.

Elife 2016 08 9;5. Epub 2016 Aug 9.

Institute of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.

Cortical expansion and folding are often linked to the evolution of higher intelligence, but molecular and cellular mechanisms underlying cortical folding remain poorly understood. The hominoid-specific gene TBC1D3 undergoes segmental duplications during hominoid evolution, but its role in brain development has not been explored. Here, we found that expression of TBC1D3 in ventricular cortical progenitors of mice via in utero electroporation caused delamination of ventricular radial glia cells (vRGs) and promoted generation of self-renewing basal progenitors with typical morphology of outer radial glia (oRG), which are most abundant in primates. Furthermore, down-regulation of TBC1D3 in cultured human brain slices decreased generation of oRGs. Interestingly, localized oRG proliferation resulting from either in utero electroporation or transgenic expression of TBC1D3, was often found to underlie cortical regions exhibiting folding. Thus, we have identified a hominoid gene that is required for oRG generation in regulating the cortical expansion and folding.
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http://dx.doi.org/10.7554/eLife.18197DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5028191PMC
August 2016

Vertical transmission of Zika virus targeting the radial glial cells affects cortex development of offspring mice.

Cell Res 2016 06 13;26(6):645-54. Epub 2016 May 13.

Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China.

The recent Zika virus (ZIKV) epidemic in Latin America coincided with a marked increase in microcephaly in newborns. However, the causal link between maternal ZIKV infection and malformation of the fetal brain has not been firmly established. Here we show a vertical transmission of ZIKV in mice and a marked effect on fetal brain development. We found that intraperitoneal (i.p.) injection of a contemporary ZIKV strain in pregnant mice led to the infection of radial glia cells (RGs) of dorsal ventricular zone of the fetuses, the primary neural progenitors responsible for cortex development, and caused a marked reduction of these cortex founder cells in the fetuses. Interestingly, the infected fetal mice exhibited a reduced cavity of lateral ventricles and a discernable decrease in surface areas of the cortex. This study thus supports the conclusion that vertically transmitted ZIKV affects fetal brain development and provides a valuable animal model for the evaluation of potential therapeutic or preventative strategies.
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http://dx.doi.org/10.1038/cr.2016.58DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4897185PMC
June 2016

The structural basis of Miranda-mediated Staufen localization during Drosophila neuroblast asymmetric division.

Nat Commun 2015 Oct 1;6:8381. Epub 2015 Oct 1.

Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry and Key Laboratory of Molecular Medicine, Ministry of Education, Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai 200433, China.

During the asymmetric division of Drosophila neuroblasts (NBs), the scaffold Miranda (Mira) coordinates the subcellular distribution of cell-fate determinants including Staufen (Stau) and segregates them into the ganglion mother cells (GMCs). Here we show the fifth double-stranded RNA (dsRNA)-binding domain (dsRBD5) of Stau is necessary and sufficient for binding to a coiled-coil region of Mira cargo-binding domain (CBD). The crystal structure of Mira514-595/Stau dsRBD5 complex illustrates that Mira forms an elongated parallel coiled-coil dimer, and two dsRBD5 symmetrically bind to the Mira dimer through their exposed β-sheet faces, revealing a previously unrecognized protein interaction mode for dsRBDs. We further demonstrate that the Mira-Stau dsRBD5 interaction is responsible for the asymmetric localization of Stau during Drosophila NB asymmetric divisions. Finally, we find the CBD-mediated dimer assembly is likely a common requirement for Mira to recognize and translocate other cargos including brain tumour (Brat).
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http://dx.doi.org/10.1038/ncomms9381DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4600727PMC
October 2015

A novel Wnt5a-Frizzled4 signaling pathway mediates activity-independent dendrite morphogenesis via the distal PDZ motif of Frizzled 4.

Dev Neurobiol 2015 Aug 1;75(8):805-22. Epub 2014 Dec 1.

Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China.

The morphology of the dendritic tree is critical to neuronal function and neural circuit wiring. Several Wnt family members have been demonstrated to play important roles in dendrite development. However, the Wnt receptors responsible for mediating this process remain largely elusive. Using primary hippocampal neuronal cultures as a model system, we report that Frizzled4 (Fzd4), a member of the Fzd family of Wnt receptors, specifically signals downstream of Wnt5a to promote dendrite branching and growth. Interestingly, the less conserved distal PDZ binding motif of Fzd4, and not its conserved proximal Dvl-interacting PDZ motif, is required for mediating this effect. We further showed that Dvl signaled parallel to and independent of Fzd4 in promoting dendrite growth. Unlike most previously described pathways, Wnt5a/Fzd4 signaling promoted dendrite development in an activity-independent and autocrine fashion. Together, these results provide the first identification of a Wnt receptor for regulating dendrite development in the mammalian system, and demonstrate a novel function of the distal PDZ motif of Fzd4 in dendrite morphogenesis, thereby expanding our knowledge of the complex roles of Wnt signaling in neural development.
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http://dx.doi.org/10.1002/dneu.22250DOI Listing
August 2015

Semaphorin 3A activates the guanosine triphosphatase Rab5 to promote growth cone collapse and organize callosal axon projections.

Sci Signal 2014 Aug 26;7(340):ra81. Epub 2014 Aug 26.

Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China.

Axon guidance (pathfinding) wires the brain during development and is regulated by various attractive and repulsive cues. Semaphorin 3A (Sema3A) is a repulsive cue, inducing the collapse of axon growth cones. In the mammalian forebrain, the corpus callosum is the major commissure that transmits information flow between the two hemispheres, and contralateral axons assemble into well-defined tracts. We found that the patterning of callosal axon projections in rodent layer II and III (L2/3) cortical neurons in response to Sema3A was mediated by the activation of Rab5, a small guanosine triphosphatase (GTPase) that mediates endocytosis, through the membrane fusion protein Rabaptin-5 and the Rab5 guanine nucleotide exchange factor (GEF) Rabex-5. Rabaptin-5 bound directly to Plexin-A1 in the Sema3A receptor complex [an obligate heterodimer formed by Plexin-A1 and neuropilin 1 (NP1)]; Sema3A enhanced this interaction in cultured neurons. Rabaptin-5 bridged the interaction between Rab5 and Plexin-A1. Sema3A stimulated endocytosis from the cell surface of callosal axon growth cones. In utero electroporation to reduce Rab5 or Rabaptin-5 impaired axon fasciculation or caused mistargeting of L2/3 callosal projections in rats. Overexpression of Rabaptin-5 or Rab5 rescued the defective callosal axon fasciculation or mistargeting of callosal axons caused by the loss of Sema3A-Plexin-A1 signaling in rats expressing dominant-negative Plexin-A1 or in NP1-deficient mice. Thus, our findings suggest that Rab5, its effector Rabaptin-5, and its regulator Rabex-5 mediate Sema3A-induced axon guidance during brain development.
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http://dx.doi.org/10.1126/scisignal.2005334DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4659511PMC
August 2014

Non-apoptotic role of caspase-3 in synapse refinement.

Neurosci Bull 2014 Aug 15;30(4):667-70. Epub 2014 Jul 15.

Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China.

Caspases, a family of cysteine proteases, mediate programmed cell death during early neural development and neurodegeneration, as well as following neurotoxic insults. Notably, accumulating lines of evidence have shown non-apoptotic roles of caspases in the structural and functional plasticity of neuronal circuits under physiological conditions, such as growth-cone dynamics and axonal/dendritic pruning, as well as neuronal excitability and plasticity. Here, we summarize recent progress on the roles of caspases in synaptic refinement.
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http://dx.doi.org/10.1007/s12264-014-1454-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5562632PMC
August 2014

MARCKS regulates membrane targeting of Rab10 vesicles to promote axon development.

Cell Res 2014 May 25;24(5):576-94. Epub 2014 Mar 25.

Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.

Axon development requires membrane addition from the intracellular supply, which has been shown to be mediated by Rab10-positive plasmalemmal precursor vesicles (PPVs). However, the molecular mechanisms underlying the membrane trafficking processes of PPVs remain unclear. Here, we show that myristoylated alanine-rich C-kinase substrate (MARCKS) mediates membrane targeting of Rab10-positive PPVs, and this regulation is critical for axon development. We found that the GTP-locked active form of Rab10 binds to membrane-associated MARCKS, whose affinity depends on the phosphorylation status of the MARCKS effector domain. Either genetic silencing of MARCKS or disruption of its interaction with Rab10 inhibited axon growth of cortical neurons, impaired docking and fusion of Rab10 vesicles with the plasma membrane, and consequently caused a loss of membrane insertion of axonal receptors responsive to extracellular axon growth factors. Thus, this study has identified a novel function of MARCKS in mediating membrane targeting of PPVs during axon development.
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http://dx.doi.org/10.1038/cr.2014.33DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4011341PMC
May 2014

Caspase-3 cleavage of dishevelled induces elimination of postsynaptic structures.

Dev Cell 2014 Mar 13;28(6):670-84. Epub 2014 Mar 13.

Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China; Graduate School, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China; School of Life Science and Technology, ShanghaiTech University, 319 Yueyang Road, Shanghai 200031, China. Electronic address:

During the development of vertebrate neuromuscular junction (NMJ), agrin stabilizes, whereas acetylcholine (ACh) destabilizes AChR clusters, leading to the refinement of synaptic connections. The intracellular mechanism underlying this counteractive interaction remains elusive. Here, we show that caspase-3, the effector protease involved in apoptosis, mediates elimination of AChR clusters. We found that caspase-3 was activated by cholinergic stimulation of cultured muscle cells without inducing cell apoptosis and that this activation was prevented by agrin. Interestingly, inhibition of caspase-3 attenuated ACh agonist-induced dispersion of AChR clusters. Furthermore, we identified Dishevelled1 (Dvl1), a Wnt signaling protein involved in AChR clustering, as the substrate of caspase-3. Blocking Dvl1 cleavage prevented induced dispersion of AChR clusters. Finally, inhibition or genetic ablation of caspase-3 or expression of a caspase-3-resistant form of Dvl1 caused stabilization of aneural AChR clusters. Thus, caspase-3 plays an important role in the elimination of postsynaptic structures during the development of NMJs.
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http://dx.doi.org/10.1016/j.devcel.2014.02.009DOI Listing
March 2014

JIP1 mediates anterograde transport of Rab10 cargos during neuronal polarization.

J Neurosci 2014 Jan;34(5):1710-23

Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China, and School of Life Sciences, Shanghai University, Shanghai 200444, China.

Axon development and elongation require strictly controlled new membrane addition. Previously, we have shown the involvement of Rab10 in directional membrane insertion of plasmalemmal precursor vesicles (PPVs) during neuronal polarization and axonal growth. However, the mechanism responsible for PPV transportation remains unclear. Here we show that c-Jun N-terminal kinase-interacting protein 1 (JIP1) interacts with GTP-locked active form of Rab10 and directly connects Rab10 to kinesin-1 light chain (KLC). The kinesin-1/JIP1/Rab10 complex is required for anterograde transport of PPVs during axonal growth. Downregulation of JIP1 or KLC or disrupting the formation of this complex reduces anterograde transport of PPVs in developing axons and causes neuronal polarity defect. Furthermore, this complex plays an important role in neocortical neuronal polarization of rats in vivo. Thus, this study has demonstrated a mechanism underlying directional membrane trafficking involved in axon development.
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http://dx.doi.org/10.1523/JNEUROSCI.4496-13.2014DOI Listing
January 2014

Myosin Vb controls biogenesis of post-Golgi Rab10 carriers during axon development.

Nat Commun 2013 ;4:2005

Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.

Polarized membrane addition is crucial for axon development and elongation during neuronal morphogenesis. This process is believed to be regulated by directed membrane trafficking of Rab10-containing post-Golgi carriers. However, the mechanisms underlying the biogenesis of these carriers remain unclear. Here, we report that Rab10 interaction with myosin Vb (MYO5B) determines the formation of Rab10 carriers and is important for axon development. Rab10 interacts with the exon D-encoded domain of MYO5B. Downregulating the expression of MYO5B (+D) or blocking its interaction with Rab10 impairs the fission of Rab10 vesicles from trans-Golgi membranes, causes a decrease in the number of Rab10 transport carriers and inhibits axon development in cultured hippocampal neurons. Furthermore, the MYO5B-Rab10 system is required for axon development of vertebrate neocortical neurons or zebrafish retinal ganglion cells in vivo. Thus, specific interaction between Rab10 and MYO5B controls the formation of Rab10 vesicles, which is required for axon development.
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http://dx.doi.org/10.1038/ncomms3005DOI Listing
December 2013

ProBDNF and mature BDNF as punishment and reward signals for synapse elimination at mouse neuromuscular junctions.

J Neurosci 2013 Jun;33(24):9957-62

Section on Neural Development and Plasticity, National Institute of Child Health and Human Development, and Genes, Cognition and Psychosis Program, National Institute of Mental Health, Bethesda, Maryland 20892-3714, USA.

During development, mammalian neuromuscular junctions (NMJs) transit from multiple-innervation to single-innervation through axonal competition via unknown molecular mechanisms. Previously, using an in vitro model system, we demonstrated that the postsynaptic secretion of pro-brain-derived neurotrophic factor (proBDNF) stabilizes or eliminates presynaptic axon terminals, depending on its proteolytic conversion at synapses. Here, using developing mouse NMJs, we obtained in vivo evidence that proBDNF and mature BDNF (mBDNF) play roles in synapse elimination. We observed that exogenous proBDNF promoted synapse elimination, whereas mBDNF infusion substantially delayed synapse elimination. In addition, pharmacological inhibition of the proteolytic conversion of proBDNF to mBDNF accelerated synapse elimination via activation of p75 neurotrophin receptor (p75(NTR)). Furthermore, the inhibition of both p75(NTR) and sortilin signaling attenuated synapse elimination. We propose a model in which proBDNF and mBDNF serve as potential "punishment" and "reward" signals for inactive and active terminals, respectively, in vivo.
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http://dx.doi.org/10.1523/JNEUROSCI.0163-13.2013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3682390PMC
June 2013

A near-infrared fluorophore for live-cell super-resolution microscopy of cellular proteins.

Nat Chem 2013 Feb 6;5(2):132-9. Epub 2013 Jan 6.

Ecole Polytechnique Fédérale de Lausanne, Institute of Chemical Sciences and Engineering (ISIC), National Centre of Competence in Research (NCCR) in Chemical Biology, 1015 Lausanne, Switzerland.

The ideal fluorescent probe for bioimaging is bright, absorbs at long wavelengths and can be implemented flexibly in living cells and in vivo. However, the design of synthetic fluorophores that combine all of these properties has proved to be extremely difficult. Here, we introduce a biocompatible near-infrared silicon-rhodamine probe that can be coupled specifically to proteins using different labelling techniques. Importantly, its high permeability and fluorogenic character permit the imaging of proteins in living cells and tissues, and its brightness and photostability make it ideally suited for live-cell super-resolution microscopy. The excellent spectroscopic properties of the probe combined with its ease of use in live-cell applications make it a powerful new tool for bioimaging.
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http://dx.doi.org/10.1038/nchem.1546DOI Listing
February 2013

P4-ATPase ATP8A2 acts in synergy with CDC50A to enhance neurite outgrowth.

FEBS Lett 2012 Jun 26;586(13):1803-12. Epub 2012 May 26.

State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences (SIBS), Graduate School of the Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China.

P(4)-ATPases are lipid flippases that transport phospholipids across cellular membranes, playing vital roles in cell function. In humans, the disruption of the P(4)-ATPase ATP8A2 gene causes a severe neurological phenotype. Here, we found that Atp8a2 mRNA was highly expressed in PC12 cells, hippocampal neurons and the brain. Overexpression of ATP8A2 increased the length of neurite outgrowth in NGF-induced PC12 cells and in primary cultures of rat hippocampal neurons. Inducing the loss of function of CDC50A in hippocampal neurons via RNA interference reduced neurite outgrowth, and the co-overexpression of CDC50A and ATP8A2 in PC12 cells enhanced NGF-induced neurite outgrowth. These results indicate that ATP8A2, acting in synergy with CDC50A, performs an important role in neurite outgrowth in neurons.
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http://dx.doi.org/10.1016/j.febslet.2012.05.018DOI Listing
June 2012

Laminin/β1 integrin signal triggers axon formation by promoting microtubule assembly and stabilization.

Cell Res 2012 Jun 20;22(6):954-72. Epub 2012 Mar 20.

Institute of Neuroscience and Key State Laboratory of Neuroscience, Chinese Academy of Sciences, Shanghai 200031, China.

Axon specification during neuronal polarization is closely associated with increased microtubule stabilization in one of the neurites of unpolarized neuron, but how this increased microtubule stability is achieved is unclear. Here, we show that extracellular matrix (ECM) component laminin promotes neuronal polarization via regulating directional microtubule assembly through β1 integrin (Itgb1). Contact with laminin coated on culture substrate or polystyrene beads was sufficient for axon specification of undifferentiated neurites in cultured hippocampal neurons and cortical slices. Active Itgb1 was found to be concentrated in laminin-contacting neurites. Axon formation was promoted and abolished by enhancing and attenuating Itgb1 signaling, respectively. Interestingly, laminin contact promoted plus-end microtubule assembly in a manner that required Itgb1. Moreover, stabilizing microtubules partially prevented polarization defects caused by Itgb1 downregulation. Finally, genetic ablation of Itgb1 in dorsal telencephalic progenitors caused deficits in axon development of cortical pyramidal neurons. Thus, laminin/Itgb1 signaling plays an instructive role in axon initiation and growth, both in vitro and in vivo, through the regulation of microtubule assembly. This study has established a linkage between an extrinsic factor and intrinsic cytoskeletal dynamics during neuronal polarization.
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http://dx.doi.org/10.1038/cr.2012.40DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3367525PMC
June 2012

Tumor protein p63/nuclear factor κB feedback loop in regulation of cell death.

J Biol Chem 2011 Dec 20;286(50):43204-13. Epub 2011 Oct 20.

Departments of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231, USA.

Tumor protein (TP)-p53 family members often play proapoptotic roles, whereas nuclear factor κB (NF-κB) functions as a proapoptotic and antiapoptotic regulator depending on the cellular environment. We previously showed that the NF-κB activation leads to the reduction of the TP63 isoform, ΔNp63α, thereby rendering the cells susceptible to cell death upon DNA damage. However, the functional relationship between TP63 isotypes and NF-κB is poorly understood. Here, we report that the TAp63 regulates NF-κB transcription and protein stability subsequently leading to the cell death phenotype. We found that TAp63α induced the expression of the p65 subunit of NF-κB (RELA) and target genes involved in cell cycle arrest or apoptosis, thereby triggering cell death pathways in MCF10A cells. RELA was shown to concomitantly modulate specific cell survival pathways, making it indispensable for the TAp63α-dependent regulation of cell death. We showed that TAp63α and RELA formed protein complexes resulted in their mutual stabilization and inhibition of the RELA ubiquitination. Finally, we showed that TAp63α directly induced RelA transcription by binding to and activating of its promoter and, in turn, leading to activation of the NF-κB-dependent cell death genes. Overall, our data defined the regulatory feedback loop between TAp63α and NF-κB involved in the activation of cell death process of cancer cells.
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http://dx.doi.org/10.1074/jbc.M111.257105DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3234803PMC
December 2011

Lgl1 activation of rab10 promotes axonal membrane trafficking underlying neuronal polarization.

Dev Cell 2011 Sep;21(3):431-44

Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.

Directed membrane trafficking is believed to be crucial for axon development during neuronal morphogenesis. However, the underlying mechanisms are poorly understood. Here, we report a role of Lgl1, the mammalian homolog of Drosophila tumor suppressor Lethal giant larvae, in controlling membrane trafficking underlying axonal growth. We find that Lgl1 is associated with plasmalemmal precursor vesicles and enriched in developing axons. Lgl1 upregulation promoted axonal growth, whereas downregulation attenuated it as well as directional membrane insertion. Interestingly, Lgl1 interacted with and activated Rab10, a small GTPase that mediates membrane protein trafficking, by releasing GDP dissociation inhibitor (GDI) from Rab10. Furthermore, Rab10 lies downstream of Lgl1 in axon development and directional membrane insertion. Finally, both Lgl1 and Rab10 are required for neocortical neuronal polarization in vivo. Thus, the Lgl1 regulation of Rab10 stimulates the trafficking of membrane precursor vesicles, whose fusion with the plasmalemma is crucial for axonal growth.
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http://dx.doi.org/10.1016/j.devcel.2011.07.007DOI Listing
September 2011

Implication of Wnt signaling in neuronal polarization.

Dev Neurobiol 2011 Jun;71(6):495-507

Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.

Wnt ligands comprise a large family of secreted glycoproteins that control a variety of developmental processes including cell polarization in diverse organisms. Through various receptors present on receiving cells, Wnts initiate intracellular signaling cascades resulting in changes in gene transcription or cytoskeleton reorganization. Recently, several lines of evidence have suggested the role of Wnt signaling in establishing axon-dendrite polarity in developing neurons. In this review, we summarize the recent results related with the role of Wnt signaling in neuronal polarization.
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http://dx.doi.org/10.1002/dneu.20851DOI Listing
June 2011

Calpain activation by Wingless-type murine mammary tumor virus integration site family, member 5A (Wnt5a) promotes axonal growth.

J Biol Chem 2011 Feb 22;286(8):6566-76. Epub 2010 Dec 22.

Institute of Neuroscience, State Key Laboratory of Neuroscience, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China.

Axon development involves spatial-temporal cytoskeletal reorganization. However, how the cytoskeleton remodeling is modulated by extracellular cues is unclear. Here, we report a role of Wnt/Ca(2+) signaling in regulating actin and growth cone dynamics. We found that treatment of cultured cortical neurons with Wnt5a, a non-canonical Wnt, either globally or locally, caused an increase in the activity of calpain, a calcium-dependent protease responsible for the cleavage of several actin binding proteins, including spectrin. Treatment with Wnt5a promoted growth cone advance, as well as axonal growth, and these effects were prevented by chelating intracellular calcium, inhibition or down-regulation of calpain, or blockade of spectrin cleavage by competitive peptides. Interestingly, both Wnt5a and activated calpain were found to be mainly distributed in the axon-rich intermediate zone of neocortex. Down-regulating calpain expression interfered with the growth of callosal axons in vivo. Thus, Wnt5a serves as a physiological cue to stimulate localized calpain activity, which in turn promotes growth cone advance and axonal growth.
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http://dx.doi.org/10.1074/jbc.M110.196568DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3057826PMC
February 2011

Nuclear factor kappaB controls acetylcholine receptor clustering at the neuromuscular junction.

J Neurosci 2010 Aug;30(33):11104-13

Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.

At the vertebrate neuromuscular junction (NMJ), acetylcholine receptor (AChR) clustering is stimulated by motor neuron-derived glycoprotein Agrin and requires a number of intracellular signal or structural proteins, including AChR-associated scaffold protein Rapsyn. Here, we report a role of nuclear factor kappaB (NF-kappaB), a well known transcription factor involved in a variety of immune responses, in regulating AChR clustering at the NMJ. We found that downregulating the expression of RelA/p65 subunit of NF-kappaB or inhibiting NF-kappaB activity by overexpression of mutated form of IkappaB (inhibitor kappaB), which is resistant to proteolytic degradation and thus constitutively keeps NF-kappaB inactive in the cytoplasma, impeded the formation of AChR clusters in cultured C2C12 muscle cells stimulated by Agrin. In contrast, overexpression of RelA/p65 promoted AChR clustering. Furthermore, we investigated the mechanism by which NF-kappaB regulates AChR clustering. Interestingly, we found that downregulating the expression of RelA/p65 caused a marked reduction in the protein and mRNA level of Rapsyn and upregulation of RelA/p65 enhanced Rapsyn promoter activity. Mutation of NF-kappaB binding site on Rapsyn promoter prevented responsiveness to RelA/p65 regulation. Moreover, forced expression of Rapsyn in RelA/p65 downregulated muscle cells partially rescued AChR clusters, suggesting that NF-kappaB regulates AChR clustering, at least partially through the transcriptional regulation of Rapsyn. In line with this notion, genetic ablation of RelA/p65 selectively in the skeletal muscle caused a reduction of AChR density at the NMJ and a decrease in the level of Rapsyn. Thus, NF-kappaB signaling controls AChR clustering through transcriptional regulation of synaptic protein Rapsyn.
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http://dx.doi.org/10.1523/JNEUROSCI.2118-10.2010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6633475PMC
August 2010

Calpain activation promotes BACE1 expression, amyloid precursor protein processing, and amyloid plaque formation in a transgenic mouse model of Alzheimer disease.

J Biol Chem 2010 Sep 1;285(36):27737-44. Epub 2010 Jul 1.

Institute of Neuroscience and State Key Laboratory of Neuroscience, Chinese Academy of Sciences, Shanghai 200031, China.

Abnormal activation of calpain is implicated in synaptic dysfunction and participates in neuronal death in Alzheimer disease (AD) and other neurological disorders. Pharmacological inhibition of calpain has been shown to improve memory and synaptic transmission in the mouse model of AD. However, the role and mechanism of calpain in AD progression remain elusive. Here we demonstrate a role of calpain in the neuropathology in amyloid precursor protein (APP) and presenilin 1 (PS1) double-transgenic mice, an established mouse model of AD. We found that overexpression of endogenous calpain inhibitor calpastatin (CAST) under the control of the calcium/calmodulin-dependent protein kinase II promoter in APP/PS1 mice caused a remarkable decrease of amyloid plaque burdens and prevented Tau phosphorylation and the loss of synapses. Furthermore, CAST overexpression prevented the decrease in the phosphorylation of the memory-related molecules CREB and ERK in the brain of APP/PS1 mice and improved spatial learning and memory. Interestingly, treatment of cultured primary neurons with amyloid-beta (Abeta) peptides caused an increase in the level of beta-site APP-cleaving enzyme 1 (BACE1), the key enzyme responsible for APP processing and Abeta production. This effect was inhibited by CAST overexpression. Consistently, overexpression of calpain in heterologous APP expressing cells up-regulated the level of BACE1 and increased Abeta production. Finally, CAST transgene prevented the increase of BACE1 in APP/PS1 mice. Thus, calpain activation plays an important role in APP processing and plaque formation, probably by regulating the expression of BACE1.
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http://dx.doi.org/10.1074/jbc.M110.117960DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2934641PMC
September 2010

Geranylgeranyltransferase I is essential for dendritic development of cerebellar Purkinje cells.

Mol Brain 2010 Jun 11;3:18. Epub 2010 Jun 11.

Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.

Background: During cerebellar development, Purkinje cells (PCs) form the most elaborate dendritic trees among neurons in the brain, but the mechanism regulating PC arborization remains largely unknown. Geranylgeranyltransferase I (GGT) is a prenyltransferase that is responsible for lipid modification of several signaling proteins, such as Rho family small GTPase Rac1, which has been shown to be involved in neuronal morphogenesis. Here we show that GGT plays an important role in dendritic development of PCs.

Results: We found that GGT was abundantly expressed in the developing rat cerebellum, in particular molecular layer (ML), the region enriched with PC dendrites. Inhibition or down-regulation of GGT using small interference RNA (siRNA) inhibited dendritic development of PCs. In contrast, up-regulation of GGT promoted dendritic arborization of PCs. Furthermore, neuronal depolarization induced by high K+ or treatment with brain-derived neurotrophic factor (BDNF) promoted membrane association of Rac1 and dendritic development of PCs in cultured cerebellar slices. The effect of BDNF or high K+ was inhibited by inhibition or down-regulation of GGT.

Conclusion: Our results indicate that GGT plays an important role in Purkinje cell development, and suggest a novel role of GGT in neuronal morphogenesis in vivo.
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http://dx.doi.org/10.1186/1756-6606-3-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2902468PMC
June 2010

Regulation of protein prenyltransferase in central neurons.

Commun Integr Biol 2009 ;2(2):138-40

Institute of Neuroscience; State Key Laboratory of Neuroscience; Shanghai Institutes for Biological Sciences; Chinese Academy of Sciences; Shanghai, China.

Geranylgeranyltransferase I (GGT) is a protein prenyltransferase that mediates lipid modification of some proteins such as Rho family small GTPases. Since the activation of Rho GTPases mediates tumorgenesis and metastasis, GGT has become an attractive target for anti-tumor drug design. Although GGT is extensively expressed in the brain, the function of GGT in central nervous system (CNS) is totally unknown. We have previously shown that GGT was involved in neuromuscular synaptogenesis. In this study, we report that neuronal activity- and brain-derived neurotropic factor (BDNF)-dependent dendritic morphogenesis requires activation of GGT. Furthermore, GGT was activated by depolarization or BDNF in cultured neurons or in hippocampus of the mice under novelty exploration test, suggesting that neuronal activity activates GGT in vitro and in vivo. In this addendum, we further discuss the significance of this study and the possible implication to the field.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2686367PMC
http://dx.doi.org/10.4161/cib.7819DOI Listing
July 2011

The role of Wnt/beta-catenin signaling in postsynaptic differentiation.

Commun Integr Biol 2008 ;1(2):158-60

Institute of Neuroscience and Key Laboratory of Neurobiology; Chinese Academy of Sciences; Shanghai P.R. China.

Synapses are basic units that mediate the communication between neurons and their target cells. The formation of synapse is regulated by secreted factors, receptors, adhesion molecules and intracellular signaling molecules. The interplay between positive and negative factors determines synapse assembling, remodeling and elimination, resulting in the formation of precise synaptic connections. However, compared to the abundant identified positive factors, negative factors are largely unknown. We have recently shown that Wnt3a acts as a negative factor that inhibits postsynaptic differentiation at the neuromuscular junction (NMJ), the synapse formed between motor neurons and skeletal muscle fibers. The clustering of acetylcholine receptor (AChR) guarantees efficient and accurate neurotransmission and is a hallmark for postsynaptic differentiation at the NMJ. We found that treatment with Wnt3a or upregulation of beta-catenin inhibited the formation of AChR clusters. Furthermore, we investigated the underlying mechanism and found that Wnt/beta-catenin signaling negatively regulated AChR clustering by downregulating the expression of Rapsyn, an AChR-associated protein required for formation and stabilization of AChR clusters.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2686008PMC
http://dx.doi.org/10.4161/cib.1.2.7099DOI Listing
October 2012