ABSTRACT
Strumpellin/Wiskott-Aldrich syndrome protein and SCAR homologue (WASH) complex subunit 5 (WASHC5) is a core component of the WASH complex, and its mutations confer pathogenicity for hereditary spastic paraplegia (HSP) type SPG8, a rare neurodegenerative gait disorder. WASH complex activates actin-related protein-2/3-mediated actin polymerization and plays a pivotal role in intracellular membrane trafficking in endosomes. In this study, we examined the role of strumpellin in the regulation of structural plasticity of cortical neurons involved in gait coordination. Administration of a lentivirus containing a strumpellin-targeting short hairpin RNA (shRNA) to cortical motor neurons lead to abnormal motor coordination in mice. Strumpellin knockdown using shRNA attenuated dendritic arborization and synapse formation in cultured cortical neurons, and this effect was rescued by wild-type strumpellin expression. Compared with the wild-type, strumpellin mutants N471D or V626F identified in patients with SPG8 exhibited no differences in rescuing the defects. Moreover, the number of F-actin clusters in neuronal dendrites was decreased by strumpellin knockdown and rescued by strumpellin expression. In conclusion, our results indicate that strumpellin regulates the structural plasticity of cortical neurons via actin polymerization.
Subject(s)
Actins , Spastic Paraplegia, Hereditary , Animals , Mice , Actins/metabolism , Endosomes/metabolism , Gait , Neurons/metabolism , RNA, Small Interfering/metabolism , Spastic Paraplegia, Hereditary/genetics , Spastic Paraplegia, Hereditary/metabolismABSTRACT
PTPRT has been known to regulate synaptic formation and dendritic arborization of hippocampal neurons. PTPRT-/- null and PTPRT-D401A mutant mice displayed enhanced depression-like behaviors compared with wild-type mice. Transient knockdown of PTPRT in the dentate gyrus enhanced the depression-like behaviors of wild-type mice, whereas rescued expression of PTPRT ameliorated the behaviors of PTPRT-null mice. Chronic stress exposure reduced expression of PTPRT in the hippocampus of mice. In PTPRT-deficient mice the expression of GluR2 (also known as GRIA2) was attenuated as a consequence of dysregulated tyrosine phosphorylation, and the long-term potentiation at perforant-dentate gyrus synapses was augmented. The inhibitory synaptic transmission of the dentate gyrus and hippocampal GABA concentration were reduced in PTPRT-deficient mice. In addition, the hippocampal expression of GABA transporter GAT3 (also known as SLC6A11) was decreased, and its tyrosine phosphorylation was increased in PTPRT-deficient mice. PTPRT-deficient mice displayed reduced numbers and neurite length of newborn granule cells in the dentate gyrus and had attenuated neurogenic ability of embryonic hippocampal neural stem cells. In conclusion, our findings show that the physiological roles of PTPRT in hippocampal neurogenesis, as well as synaptic functions, are involved in the pathogenesis of depressive disorder.
Subject(s)
Depression , Neurogenesis , Animals , Dentate Gyrus , Hippocampus , Mice , Mice, Knockout , Neurogenesis/genetics , Neurons , SynapsesABSTRACT
DNA-functionalized gold nanoparticles (AuNPs) are used for various bioapplications, such as biosensor development and drug delivery. Nevertheless, no study has reported the effect of polynucleotide chains on chemical interface damping (CID), the most recently proposed plasmon damping pathway in single AuNPs. In this study, we conducted total internal reflection scattering measurements of gold nanorods (AuNRs) to reveal the CID effect induced by amine (NH2)-linked polynucleotides (or DNA) with guanine-rich sequences through the interaction between nitrogen and Au surfaces. Additionally, we elucidated the effect of a linear hydrocarbon chain length between NH2 and DNA (NH2-Cn-DNA, n = 6, 12, 18, 24) on spectral changes in single AuNRs. The localized surface plasmon resonance (LSPR) linewidth increased with an increasing number of linear carbon, from 6 to 24, due to the increase in van der Waals forces. Second, the effect of the direction (5' or 3' ends) of DNA attachment to the AuNR surfaces on LSPR spectral changes was investigated, and there was no significant difference in LSPR wavelength and full linewidth at half-maximum shifts caused by the DNA attachment directions (5' or 3' ends). Third, guanine-rich DNA can fold into four-stranded secondary structures called G-quadruplexes (GQs). We demonstrated the effect of linear carbon chain length, between NH2 and GQs, on CID in single AuNRs. Lastly, a label-free detection of DNA hybridization events on single AuNRs was demonstrated for sensing applications. Thus, we provide an insight into the effect of amine-functionalized guanine-rich DNA with different carbon chains on LSPR spectral changes, including CID in single AuNRs.
Subject(s)
Metal Nanoparticles , Nanotubes , Amines , Carbon , DNA , Gold/chemistry , Guanine , Nanotubes/chemistry , Poly GABSTRACT
The balance between the actions of protein kinases and phosphatases is crucial for neuronal functions, including synaptic plasticity. Although the phosphorylation and dephosphorylation of neuronal proteins are regulated by synaptic plasticity, no systematic analyses of this have yet been conducted. We performed a phosphoproteomic analysis of hippocampal synaptic plasticity using a nano-Acquity/Synapt LC-MS/MS system. Neuronal proteins were extracted from hippocampal tissues and cultured neurons exposed to long-term potentiation (LTP) or long-term depression (LTD). Filter-aided sample preparation (FASP) was performed to remove residual anionic detergents for complete tryptic digestion. Phosphopeptides were then enriched using TiO2 chromatography, followed by immunoaffinity chromatography with an anti-phosphotyrosine antibody. Among the 1500 phosphopeptides identified by LC-MS/MS, 374 phosphopeptides were detected simultaneously in both hippocampal tissues and cultured neurons. Semi-quantification counting the number of spectra of each phosphopeptide showed that 42 of 374 phosphopeptides changed significantly depending on synaptic plasticity. In conclusion, a new proteomic method using sequential enrichment of phosphopeptides and semi-quantification enabled the phosphoproteomic analysis of hippocampal synaptic plasticity.
Subject(s)
Phosphopeptides , Proteomics , Chromatography, Liquid , Hippocampus/metabolism , Long-Term Synaptic Depression/physiology , Neuronal Plasticity/physiology , Phosphopeptides/chemistry , Proteome/metabolism , Proteomics/methods , Tandem Mass Spectrometry/methodsABSTRACT
This study investigated the amalgamation of gold nanorods (AuNRs) exposed to Hg(II) solution and its effects on structural and spectral changes in single AuNRs using scanning electron microscopy and total internal reflection scattering microscopy. First, Hg adsorption on AuNR surfaces formed AuNRs@Hg core-shell structures. Afterwards, they transformed to AuNRs@AuHg alloy shell structures in air due to the slow inward diffusion of Hg over time. The aspect ratio (AR) of the AuNRs@AuHg formed by the amalgamation was significantly decreased compared to that of bare AuNRs. Furthermore, the Hg coating on AuNRs induced a dramatic blue shift of the localized surface plasmon resonance (LSPR) peak and linewidth broadening, followed by a red shift and linewidth narrowing of the LSPR peak due to inward diffusion of Hg into the AuNR core. Finally, we investigated the effects of oxygen plasma treatment on the structural changes of AuNRs@AuHg and found that their AR was a decreasing function of the plasma treatment time. More notably, a major structural change was observed 5 min after the plasma treatment. Therefore, fundamental information on the relationship among amalgamation process, plasma treatment time, structural change, and LSPR peak and linewidth is provided at the single-particle level.
Subject(s)
Mercury , Nanotubes , Gold/chemistry , Microscopy , Nanotubes/chemistry , Surface Plasmon ResonanceABSTRACT
This paper shows how oxygen plasma treatment affects the structural, localized surface plasmon resonance (LSPR) spectral, and spatial orientation changes in single gold nanorods coated with a mesoporous silica shell (AuNRs@SiO2) in comparison with bare AuNRs with the same aspect ratio (AR). Single AuNRs@SiO2 subjected to different plasma treatment times were characterized using scanning electron microscopy and total internal reflection scattering (TIRS) microscopy and spectroscopy. The AR of the single AuNRs without a silica shell was decreased by structural deformation, while their LSPR linewidth was increased with increasing plasma treatment time. In contrast, single AuNRs@SiO2 showed much higher structural and spectral stability due to the silica shell under the energetic plasma treatment. Furthermore, there was no noticeable variation in the three-dimensional (3D) orientations of single AuNR cores in the silica shell before and after the plasma treatment. The results support that no significant structural and spectral changes occur in single AuNRs@SiO2 and that the silica coating enhances the stability of AuNR cores against oxygen plasma treatment. Therefore, fundamental information on the relationship among plasma treatment time, structural change, LSPR damping, and defocused orientation patterns is provided at the single-particle level.
Subject(s)
Gold , Nanotubes , Microscopy , Oxygen , Silicon Dioxide , Spectrum AnalysisABSTRACT
Total internal reflection scattering (TIRS) microscopy is based on evanescent field illumination at the interface. Compared to conventional dark-field (DF) microscopy, TIRS microscopy has been rarely applied to the spectroscopic studies of plasmonic nanoparticles. Furthermore, there has been no detailed correlation study on the characteristic optical properties of single gold nanorods (AuNRs) obtained by DF and TIRS microscopy. Herein, through a single-particle correlation study, we compare the spectroscopic and defocusing properties of single AuNRs obtained by DF and TIRS microscopy, which have different illumination geometries. Compared to DF microscopy, TIRS microscopy yielded almost identical single-particle scattering spectra and localized surface plasmon resonance (LSPR) linewidth for the same in-focus AuNRs. However, TIRS microscopy, which is based on evanescent field illumination at the interface, provided a higher signal-to-noise ratio in the defocused image of the same AuNRs compared to DF microscopy. Furthermore, the heavily reduced background noise clarified the defocused scattering patterns of TIRS microscopy, which provided more detailed and accurate angular information than that obtained by conventional DF microscopy.
ABSTRACT
Copine 1 (CPNE1) is a well-known phospholipid binding protein in plasma membrane of various cell types. In brain cells, CPNE1 is closely associated with AKT signaling pathway, which is important for neural stem cell (NSC) functions during brain development. Here, we investigated the role of CPNE1 in the regulation of brain NSC functions during brain development and determined its underlying mechanism. In this study, abundant expression of CPNE1 was observed in neural lineage cells including NSCs and immature neurons in human. With mouse brain tissues in various developmental stages, we found that CPNE1 expression was higher at early embryonic stages compared to postnatal and adult stages. To model developing brain in vitro, we used primary NSCs derived from mouse embryonic hippocampus. Our in vitro study shows decreased proliferation and multi-lineage differentiation potential in CPNE1 deficient NSCs. Finally, we found that the deficiency of CPNE1 downregulated mTOR signaling in embryonic NSCs. These data demonstrate that CPNE1 plays a key role in the regulation of NSC functions through the activation of AKT-mTOR signaling pathway during brain development.
Subject(s)
Brain/embryology , Calcium-Binding Proteins/metabolism , Neural Stem Cells/cytology , Neurogenesis , Animals , Brain/cytology , Brain/metabolism , Cell Line , Cells, Cultured , Embryonic Stem Cells/cytology , Embryonic Stem Cells/metabolism , Humans , Mice, Inbred C57BL , Neural Stem Cells/metabolism , Signal Transduction , TOR Serine-Threonine Kinases/metabolismABSTRACT
In G-rich DNA, it is well known that the form changes from single-strand DNA to G-quadruplex due to cations. In this study, we analyze the diffusion coefficient and fluorescence intensity obtained by fluorescence correlation spectroscopy for short G-rich DNA of the (G3T1)4 sequence labeled as 5-Carboxytetramethylrhodamine (TAMRA) with variation of the K+ ion concentration. At a K+ ion concentration of more than 200 mM, the single-strand DNA was changed to the G-quadruplex. The size of the G-quadruplex decreased to 86% than the size of the single strand DNA at K+ ion concentration of 0 M. The size of the G-quadruplex and the fluorescence intensity of TAMRA attached to the DNA were constant with an increase in the K+ ion concentration between 200 and 800 mM. This means that the size of the DNA and the fluorescence intensity of the TAMRA are not affected by the K+ ion concentration at the G-quadruplex structure because the binding structure of DNA and TAMRA dye leads to stability at a concentration of less than 100 mM K+. Based on our short G-rich DNA results, longer G-rich DNA is analyzed for the diffusion coefficient of the DNA and the fluorescence intensity variation of fluorescence dye attached to the DNA.
Subject(s)
DNA/chemistry , Fluorescence , Fluorescent Dyes/chemistry , G-Quadruplexes , Nucleic Acid Conformation , Spectrometry, Fluorescence/methods , Cations/chemistry , HumansABSTRACT
We report the first cradle-to-gate emissions assessment for a mass-produced battery in a commercial battery electric vehicle (BEV); the lithium-ion battery pack used in the Ford Focus BEV. The assessment was based on the bill of materials and primary data from the battery industry, that is, energy and materials input data from the battery cell and pack supplier. Cradle-to-gate greenhouse gas (GHG) emissions for the 24 kWh Ford Focus lithium-ion battery are 3.4 metric tonnes of CO2-eq (140 kg CO2-eq per kWh or 11 kg CO2-eq per kg of battery). Cell manufacturing is the key contributor accounting for 45% of the GHG emissions. We review published studies of GHG emissions associated with battery production to compare and contrast with our results. Extending the system boundary to include the entire vehicle we estimate a 39% increase in the cradle-to-gate GHG emissions of the Focus BEV compared to the Focus internal combustion engine vehicle (ICEV), which falls within the range of literature estimates of 27-63% increases for hypothetical nonproduction BEVs. Our results reduce the uncertainties associated with assessment of BEV battery production, serve to identify opportunities to reduce emissions, and confirm previous assessments that BEVs have great potential to reduce GHG emissions over the full life cycle and provide local emission free mobility.
Subject(s)
Electric Power Supplies , Lithium , Electricity , Greenhouse Effect , Ions , Vehicle EmissionsABSTRACT
KIF1A is a neuron-specific motor protein that plays important roles in cargo transport along neurites. Recessive mutations in KIF1A were previously described in families with spastic paraparesis or sensory and autonomic neuropathy type-2. Here, we report 11 heterozygous de novo missense mutations (p.S58L, p.T99M, p.G102D, p.V144F, p.R167C, p.A202P, p.S215R, p.R216P, p.L249Q, p.E253K, and p.R316W) in KIF1A in 14 individuals, including two monozygotic twins. Two mutations (p.T99M and p.E253K) were recurrent, each being found in unrelated cases. All these de novo mutations are located in the motor domain (MD) of KIF1A. Structural modeling revealed that they alter conserved residues that are critical for the structure and function of the MD. Transfection studies suggested that at least five of these mutations affect the transport of the MD along axons. Individuals with de novo mutations in KIF1A display a phenotype characterized by cognitive impairment and variable presence of cerebellar atrophy, spastic paraparesis, optic nerve atrophy, peripheral neuropathy, and epilepsy. Our findings thus indicate that de novo missense mutations in the MD of KIF1A cause a phenotype that overlaps with, while being more severe, than that associated with recessive mutations in the same gene.
Subject(s)
Cognition Disorders/genetics , Kinesins/chemistry , Kinesins/genetics , Nervous System Diseases/genetics , Paraparesis, Spastic/genetics , Adolescent , Adult , Child , Child, Preschool , Cognition Disorders/pathology , Epilepsy/genetics , Epilepsy/pathology , Hereditary Sensory and Autonomic Neuropathies/genetics , Hereditary Sensory and Autonomic Neuropathies/pathology , Humans , Male , Models, Molecular , Mutation, Missense , Nervous System Diseases/pathology , Paraparesis, Spastic/pathology , Peripheral Nervous System Diseases/genetics , Peripheral Nervous System Diseases/pathology , Protein Structure, Tertiary , Young AdultABSTRACT
We built a polarization fluorescence correlation spectroscopy system to analyze the variation of the correlation function in rotational diffusion based on the length of rod-like fluorescent particles. Because the rotational diffusion of particles in liquid depends on the relative polarization states of the laser source and particle fluorescence, we compared the amplitudes of the rotational diffusion using the autocorrelation function in different polarization states. For experiments that depend on the length of the fluorescent particles, we prepared three kinds of quantum rod samples with a width of 6.5 ± 0.5 nm and lengths of 17 ± 3, 40 ± 3, and 46 ± 3 nm. Through the experiment, we obtained the hydrodynamic radii of each particle using the rotational diffusion coefficient: 10.7 ± 0.8, 13.4 ± 0.7, and 14.1 ± 0.4 nm with the length of the particles. All the obtained values for radii are 3 nm larger than the calculated equivalent radii of spheres with the same volume as the rod samples. Through a fraction analysis by polarization state, we confirmed that the ratio of rotational fraction for polarization increases with the aspect ratio of the actual particle.
Subject(s)
Quantum Dots/chemistry , Cadmium Compounds/chemistry , Diffusion , Hydrodynamics , Rotation , Selenium Compounds/chemistry , Spectrometry, Fluorescence , Sulfides/chemistryABSTRACT
Little is known about the genetics of nonsyndromic intellectual disability (NSID). We hypothesized that de novo mutations (DNMs) in synaptic genes explain an important fraction of sporadic NSID cases. In order to investigate this possibility, we sequenced 197 genes encoding glutamate receptors and a large subset of their known interacting proteins in 95 sporadic cases of NSID. We found 11 DNMs, including ten potentially deleterious mutations (three nonsense, two splicing, one frameshift, four missense) and one neutral mutation (silent) in eight different genes. Calculation of point-substitution DNM rates per functional and neutral site showed significant excess of functional DNMs compared to neutral ones. De novo truncating and/or splicing mutations in SYNGAP1, STXBP1, and SHANK3 were found in six patients and are likely to be pathogenic. De novo missense mutations were found in KIF1A, GRIN1, CACNG2, and EPB41L1. Functional studies showed that all these missense mutations affect protein function in cell culture systems, suggesting that they may be pathogenic. Sequencing these four genes in 50 additional sporadic cases of NSID identified a second DNM in GRIN1 (c.1679_1681dup/p.Ser560dup). This mutation also affects protein function, consistent with structural predictions. None of these mutations or any other DNMs were identified in these genes in 285 healthy controls. This study highlights the importance of the glutamate receptor complexes in NSID and further supports the role of DNMs in this disorder.
Subject(s)
Glutamic Acid/genetics , Intellectual Disability/genetics , Mutation/genetics , Amino Acid Substitution/genetics , Animals , Base Sequence , Calcium Channels/genetics , Calcium Channels/metabolism , Cytoskeletal Proteins/genetics , Cytoskeletal Proteins/metabolism , Female , HEK293 Cells , Humans , Kinesins/genetics , Male , Membrane Proteins/genetics , Membrane Proteins/metabolism , Mutation, Missense/genetics , Neuropeptides/genetics , Neuropeptides/metabolism , Phenotype , Protein Binding/genetics , Protein Transport , RNA Splicing/genetics , Rats , Receptors, AMPA/metabolism , Receptors, N-Methyl-D-Aspartate/genetics , Subcellular Fractions/metabolism , SyndromeABSTRACT
Dendritic arborization is important for neuronal development as well as the formation of neural circuits. Rac1 is a member of the Rho GTPase family that serve as regulators of neuronal development. Breakpoint cluster region protein (BCR) is a Rac1 GTPase-activating protein that is abundantly expressed in the central nervous system. Here, we show that BCR plays a key role in neuronal development. Dendritic arborization and actin polymerization were attenuated by overexpression of BCR in hippocampal neurons. Knockdown of BCR using specific shRNAs increased the dendritic arborization as well as actin polymerization. The number of dendrites in null mutant BCR(-/-) mice was considerably increased compared with that in wild-type mice. We found that the function of the BCR GTPase-activating domain could be modulated by protein tyrosine phosphatase receptor T (PTPRT), which is expressed principally in the brain. We demonstrate that tyrosine 177 of BCR was the main target of PTPRT and the BCR mutant mimicking dephosphorylation of tyrosine 177 alleviated the attenuation of dendritic arborization. Additionally the attenuated dendritic arborization found upon BCR overexpression was relieved upon co-expression of PTPRT. When PTPRT was knocked down by a specific shRNA, the dendritic arborization was significantly reduced. The activity of the BCR GTPase-activating domain was modulated by means of conversions between the intra- and inter-molecular interactions, which are finely regulated through the dephosphorylation of a specific tyrosine residue by PTPRT. We thus show conclusively that BCR is a novel substrate of PTPRT and that BCR is involved in the regulation of neuronal development via control of the BCR GTPase-activating domain function by PTPRT.
Subject(s)
Dendrites/metabolism , GTPase-Activating Proteins/metabolism , Proto-Oncogene Proteins c-bcr/metabolism , Receptor-Like Protein Tyrosine Phosphatases, Class 2/metabolism , rac1 GTP-Binding Protein/metabolism , Actins/metabolism , Amino Acid Sequence , Animals , Gene Knockdown Techniques , HEK293 Cells , Humans , Mice , Mice, Knockout , Molecular Sequence Data , Phosphorylation , Phosphotyrosine/metabolism , Polymerization , Protein Structure, Tertiary , Proto-Oncogene Proteins c-bcr/chemistry , Proto-Oncogene Proteins c-bcr/deficiency , Rats , Sequence Deletion , Signal Transduction , Substrate SpecificityABSTRACT
Fluorescent particles show the variety characteristics by the interaction with other particles and solvent. In order to investigate the relationship between the dynamic properties of fluorescent particles and solvent viscosity, particle diffusion in various solvents was evaluated using a fluorescence correlation spectroscopy. Upon analyzing the correlation functions of AF-647, Q-dot, and beads with different viscosity values, the diffusion time of all particles was observed to increase with increasing solvent viscosity, and the ratio of diffusion time to solvent viscosity, τ D /η, showed a linear dependence on particle size. The particle diffusion coefficients calculated from the diffusion time decreased with increasing solvent viscosity. Further, the hydrodynamic radii of AF-647, Q-dot, and beads were 0.98 ± 0.1 nm, 64.8 ± 3.23 nm, and 89.8 ± 4.91 nm, respectively, revealing a linear dependence on τ D /η, which suggests that the hydrodynamic radius of a particle strongly depends on both the physical size of the particle and solvent viscosity.
ABSTRACT
To measure the polarization dependence of fluorescent probes, a confocal-microscope-based polarized fluorescence correlation spectroscopy system was developed, and the polarization dependence on the rotational diffusion of well-defined quantum rods (Qrods) was investigated and characterized. The rotational diffusion region of the Qrods was observed over a time range of less than 10(-5) s in a water solution, and the rotational diffusion parameters were extracted using a rotational diffusion model in which the viscosity of the solution media was varied. Our work demonstrated that polarized fluorescence correlation spectroscopy (FCS) is useful for investigating both the rotational and translational diffusion of fluorescent probes.
Subject(s)
Diffusion , Fluorescent Dyes/chemistry , Quantum Dots , Spectrometry, FluorescenceABSTRACT
Chemical interface damping (CID) is a recently proposed plasmon-damping pathway based on the interfacial hot-electron transfer from metal to adsorbate molecules. However, the in situ reversible tuning of CID in single gold nanorods (AuNRs) has remained a considerable challenge. In this study, we used total internal reflection scattering microscopy and spectroscopy to investigate the CID induced by p-aminoazobenzene (p-AAB), which has fast photoisomerization characteristics, attached to single AuNRs. We demonstrated the in situ reversible tuning of CID in single AuNRs by switching between ultraviolet (UV, 365 nm) and visible (vis, 465 nm) irradiation to induce photoresponsive structural conversions between the cis and trans forms of p-AAB in ethanol, leading to different lowest unoccupied molecular orbital (LUMO) energies for both forms. The localized surface plasmon resonance (LSPR) line width was wide under vis irradiation but narrow under UV irradiation, indicating that hot electrons are more efficiently transferred to trans-p-AAB with a low LUMO energy level. We further investigated the in situ photoreversible tuning of CID by manipulating supramolecular host-guest interactions between cucurbit[8]uril (CB[8]) and p-AAB in the single AuNRs. Additionally, real-time in situ reversible tuning of CID in single AuNRs was achieved through photonic switching of the cis-trans forms of p-AAB inside CB[8]. The LSPR line width was narrow under vis irradiation but gradually widened under UV irradiation before narrowing again upon returning to vis irradiation, unlike the case with p-AAB only. These results can be ascribed to the fact that cis-p-AAB completely encapsulated within CB[8] in water is thermodynamically more favorable than trans-p-AAB. Therefore, we have discovered a new strategy for tuning the CID by performing p-AAB photoisomerization and adjusting the wavelength of incident light in single AuNRs. In addition, this study demonstrates that CID can be effectively applied to the development of biosensors to detect guest molecules and their structural changes inside the cavity of CB[8] in single AuNRs.
ABSTRACT
The receptor-type protein tyrosine phosphatases (RPTPs) have been linked to signal transduction, cell adhesion, and neurite extension. PTPRT/RPTPrho is exclusively expressed in the central nervous system and regulates synapse formation by interacting with cell adhesion molecules and Fyn protein tyrosine kinase. Overexpression of PTPRT in cultured neurons increased the number of excitatory and inhibitory synapses by recruiting neuroligins that interact with PTPRT through their ecto-domains. In contrast, knockdown of PTPRT inhibited synapse formation and withered dendrites. Incubation of cultured neurons with recombinant proteins containing the extracellular region of PTPRT reduced the number of synapses by inhibiting the interaction between ecto-domains. Synapse formation by PTPRT was inhibited by phosphorylation of tyrosine 912 within the membrane-proximal catalytic domain of PTPRT by Fyn. This tyrosine phosphorylation reduced phosphatase activity of PTPRT and reinforced homophilic interactions of PTPRT, thereby preventing the heterophilic interaction between PTPRT and neuroligins. These results suggest that brain-specific PTPRT regulates synapse formation through interaction with cell adhesion molecules, and this function and the phosphatase activity are attenuated through tyrosine phosphorylation by the synaptic tyrosine kinase Fyn.
Subject(s)
Cell Adhesion Molecules/metabolism , Proto-Oncogene Proteins c-fyn/metabolism , Receptor-Like Protein Tyrosine Phosphatases, Class 2/metabolism , Receptor-Like Protein Tyrosine Phosphatases, Class 2/physiology , Synapses/metabolism , Animals , Brain/metabolism , Cells, Cultured , Guinea Pigs , Humans , Mice , Models, Biological , Neurons/metabolism , Phosphorylation , Protein Binding , RNA, Small Interfering/pharmacology , Rats , Receptor-Like Protein Tyrosine Phosphatases, Class 2/antagonists & inhibitors , Receptor-Like Protein Tyrosine Phosphatases, Class 2/genetics , Synapses/drug effects , Synapses/genetics , Synapses/physiology , Synaptic Transmission/drug effects , Synaptic Transmission/genetics , Synaptic Transmission/physiologyABSTRACT
PTPRT (protein tyrosine phosphatase receptor T), a brain-specific tyrosine phosphatase, has been found to regulate synaptic formation and development of hippocampal neurons, but its regulation mechanism is not yet fully understood. Here, Syntaxin-binding protein 1, a key component of synaptic vesicle fusion machinery, was identified as a possible interaction partner and an endogenous substrate of PTPRT. PTPRT interacted with Syntaxin-binding protein 1 in rat synaptosome, and co-localized with Syntaxin-binding protein 1 in cultured hippocampal neurons. PTPRT dephosphorylated tyrosine 145 located around the linker between domain 1 and 2 of Syntaxin-binding protein 1. Syntaxin-binding protein 1 directly binds to Syntaxin 1, a t-SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) protein, and plays a role as catalysts of SNARE complex formation. Syntaxin-binding protein 1 mutant mimicking non-phosphorylation (Y145F) enhanced the interaction with Syntaxin 1 compared to wild type, and therefore, dephosphorylation of Syntaxin-binding protein 1 appeared to be important for SNARE-complex formation. In conclusion, PTPRT could regulate the interaction of Syntaxin-binding protein 1 with Syntaxin 1, and as a result, the synaptic vesicle fusion appeared to be controlled through dephosphorylation of Syntaxin-binding protein 1.
Subject(s)
Munc18 Proteins/metabolism , Protein Tyrosine Phosphatases/metabolism , Receptor-Like Protein Tyrosine Phosphatases, Class 2/metabolism , Tyrosine/chemistry , Animals , Cells, Cultured , Cloning, Molecular , HEK293 Cells , Hippocampus/cytology , Humans , Mutation , Neurons/metabolism , Phosphorylation , Protein Binding , Rats , SNARE Proteins/metabolism , Substrate SpecificityABSTRACT
As global plastic production continues to grow, microplastics released from a massive quantity of plastic wastes have become a critical environmental concern. These microplastic particles are found in a wide range of living organisms in a diverse array of ecosystems. In this study, we investigated the biological effects of polystyrene nanoplastic (PSNP) on development of the central nervous system using cultured neural stem cells (NSCs) and mice exposed to PSNP during developmental stages. Our study demonstrates that maternal administration of PSNP during gestation and lactating periods altered the functioning of NSCs, neural cell compositions, and brain histology in progeny. Similarly, PSNP-induced molecular and functional defects were also observed in cultured NSCs in vitro. Finally, we show that the abnormal brain development caused by exposure to high concentrations of PSNP results in neurophysiological and cognitive deficits in a gender-specific manner. Our data demonstrate the possibility that exposure to high amounts of PSNP may increase the risk of neurodevelopmental defects.