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Mutations of the X-linked methyl-CpG-binding protein 2 (MECP2) gene in humans are responsible for most cases of Rett syndrome (RTT), an X-linked progressive neurological disorder. While genome-wide screens in clinical trials have revealed several putative RTT-associated mutations in MECP2, their causal relevance regarding the functional regulation of MeCP2 at the etiologic sites at the protein level requires more evidence. In this study, we demonstrated that MeCP2 was dynamically modified by O-linked-β-N-acetylglucosamine (O-GlcNAc) at threonine 203 (T203), an etiologic site in RTT patients. Disruption of the O-GlcNAcylation of MeCP2 specifically at T203 impaired dendrite development and spine maturation in cultured hippocampal neurons, and disrupted neuronal migration, dendritic spine morphogenesis, and caused dysfunction of synaptic transmission in the developing and juvenile mouse cerebral cortex. Mechanistically, genetic disruption of O-GlcNAcylation at T203 on MeCP2 decreased the neuronal activity-induced induction of Bdnf transcription. Our study highlights the critical role of MeCP2 T203 O-GlcNAcylation in neural development and synaptic transmission potentially via brain-derived neurotrophic factor.
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Animals , Humans , Mice , Methyl-CpG-Binding Protein 2/metabolism , Neurodevelopmental Disorders/genetics , Rett Syndrome/genetics , Synaptic Transmission , ThreonineABSTRACT
Abstract Hippocampus is a part of the brain that has a major role in spatial learning and memory which can be affected by herbal extracts. Incense resin (Styrax benzoin) has been used by local communities to improve intelligence. However, there is no scientific evidence of the functions of Styrax benzoin for regulating hippocampal function. The aim of this study was intended to analyze and investigate the effect of incense resin on learning, memory, and dendrite complexity of mice. Three months old male Deutch Democratic Yokohama (DDY) mice were injected orally with graded doses of 100, 150, and 200 mg/kg of incense resin aqueous extract daily for 30 days. Spatial learning and memory performance levels were tested with Y-maze alternation, novel object recognition, and Morris water maze. The branches and maximum dendritic span in the dentate gyrus were observed by the Golgi-Cox staining. Overall, our results showed that incense resin extract increased learning and memory ability, and the number of dendrite branching in the dentate gyrus.
Subject(s)
Animals , Male , Mice , Dendritic Cells/drug effects , Plant Extracts/pharmacology , Styrax/chemistry , Spatial Learning/drug effects , Memory/drug effects , Administration, Oral , Maze Learning/drug effectsABSTRACT
Monitoring neuronal activity in vivo is critical to understanding the physiological or pathological functions of the brain. Two-photon Ca imaging in vivo using a cranial window and specific neuronal labeling enables real-time, in situ, and long-term imaging of the living brain. Here, we constructed a recombinant rabies virus containing the Ca indicator GCaMP6s along with the fluorescent protein DsRed2 as a baseline reference to ensure GCaMP6s signal reliability. This functional tracer was applied to retrogradely label specific V1-thalamus circuits and detect spontaneous Ca activity in the dendrites of V1 corticothalamic neurons by in vivo two-photon Ca imaging. Notably, we were able to record single-spine spontaneous Ca activity in specific circuits. Distinct spontaneous Ca dynamics in dendrites of V1 corticothalamic neurons were found for different V1-thalamus circuits. Our method can be applied to monitor Ca dynamics in specific input circuits in vivo, and contribute to functional studies of defined neural circuits and the dissection of functional circuit connections.
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Jan Evangelista Purkinje was a Czech physician with an exceptional capacity for innovative thinking, and he was one of the fathers of experimental physiology, experimental pharmacology, experimental psychology, histology, embryology, and physical anthropology. Several achievements are named after him, from his prodigious productivity. Of special interest of this paper was his pioneering role in the rise of experimental physiology, microscopical anatomy, and histological methods by the 1830´s that allowed him define more accurate data concerning the structure of nerve tissue of animals and humans such as the now known "Purkinje's cells" and others cells of the brain. He investigated the structure of neuronal processes, including the dendrites. Purkinje recognized possible functional differences between a variety of types of neurons and speculated about their interrelations. He was one of the great geniuses of science.
Jan Evangelista Purkinje foi um médico checo com excepcional capacidade de pensamento inovador e um dos pais da fisiologia experimental, farmacologia experimental, psicologia experimental, histologia, embriologia e antropologia física. Várias conquistas receberam o nome dele, de sua produtividade prodigiosa. De interesse especial deste trabalho enaltece-se o seu papel pioneiro no surgimento da fisiologia experimental, anatomia microscópica e métodos histológicos na década de 1830. Isso permitiu que ele definisse dados mais precisos sobre a estrutura do tecido nervoso de animais e humanos, como as agora conhecidas "células de Purkinje" e outras células do cérebro. Ele investigou a estrutura dos processos neuronais, incluindo os dendritos. Purkinje reconheceu possíveis diferenças funcionais entre uma variedade de tipos de neurônios e especulou sobre suas inter-relações. Ele foi um dos grandes gênios da ciência.
Subject(s)
Humans , History, 19th Century , Physicians/history , Physiology/history , Purkinje Cells/cytology , Dendrites , Nerve Tissue , Ophthalmology/history , Czech Republic , Anatomy/historyABSTRACT
Ras-related C3 botulinum toxin substrate 1 (Rac1), a member of the Rho GTPase family which plays important roles in dendritic spine morphology and plasticity, is a key regulator of cytoskeletal reorganization in dendrites and spines. Here, we investigated whether and how Rac1 modulates synaptic transmission in mouse retinal ganglion cells (RGCs) using selective conditional knockout of Rac1 (Rac1-cKO). Rac1-cKO significantly reduced the frequency of AMPA receptor-mediated miniature excitatory postsynaptic currents, while glycine/GABA receptor-mediated miniature inhibitory postsynaptic currents were not affected. Although the total GluA1 protein level was increased in Rac1-cKO mice, its expression in the membrane component was unchanged. Rac1-cKO did not affect spine-like branch density in single dendrites, but significantly reduced the dendritic complexity, which resulted in a decrease in the total number of dendritic spine-like branches. These results suggest that Rac1 selectively affects excitatory synaptic transmission in RGCs by modulating dendritic complexity.
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In this study, change of optical properties and microstructure of an Ag-Pd-In alloy according to Ag content was investigated. For this purpose, specimen alloys were prepared by adding 0–100 wt.% of Ag to the 50Pd-50In (wt.%) alloy. When the content of Ag was more than 40 wt.%, the color difference with pure gold specimen was increased(p < 0.001). L* value increased as the Ag content of the specimen increased, but a* and b* value increased until the addition of 20 wt.% Ag, and then decreased with increasing Ag content(p < 0.001). Ag-free specimen was single phase in the as-cast state, but when the content of Ag was more than 20 wt.%, the phase separation occurred and two phases of matrix and dendrite or granular structure were confirmed. The dendrite or granular structure was composed of the InPd phase, and the matrix was composed of the Ag-rich phase. From these results, it can be concluded that the specimens with Ag content of 20–70 wt.% have the Ag-rich matrix which has a high L* value and low a* and b* value, and have the dendrite structure which has a low L* value and high a* and b* value. As the content of Ag increased, the color changed from light yellow to silver white due to the increase in the ratio of the matrix to the dendrite or granular structure.
Subject(s)
Alloys , Dendrites , SilverABSTRACT
Objective To determine whether the integration of immature neurons born before status epilepticus (SE)can be disrupted by an epileptogenic insult.Methods Pilocarpine was used to induce SE in mice. At week 1 before induction,BrdU or retroviral vector expressing green fluorescent protein (RV-GFP)was used to label the newly born cells in the dentate gyrus (DG).At week 8 after SE,BrdU+Map2 or BrdU+NeuN double-labeling staining was carried out to visualize hilar basal dendrite or hilar ectopic migration.Virus-transduced GFP signals were used to identify the mossy fiber sprouting from the newly generated neurons.The number of cells with aberrant integrations was compared using unpaired Student's t-test.Results The percentage of newborn neurons with aberrant dendritic morphology was (20.8±8.4)% at week 8 after SE.The percentage of BrdU+NeuN double labeled cells ectopically migrated into the hilus was (15.9 ± 7.4)%.At week 8 after SE,the chronically epileptic mice showed many GFP+ processes in the IML with the same axonal appearance and small mossy fiber bouton-like structures as those seen in the hilus.The number of newborn neurons with aberrant integrations in SE mice wassignificantly increased when compared with the control mice (P <0.05).Conclusion These data demonstrate the existence of aberrant integrations-hilar basal dendrites,hilar ectopic migration and mossy fiber sprouting in the DG-generated cells born 1 week before an SE insult.
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Objective To determine whether the integration of immature neurons born before status epilepticus (SE)can be disrupted by an epileptogenic insult.Methods Pilocarpine was used to induce SE in mice. At week 1 before induction,BrdU or retroviral vector expressing green fluorescent protein (RV-GFP)was used to label the newly born cells in the dentate gyrus (DG).At week 8 after SE,BrdU+Map2 or BrdU+NeuN double-labeling staining was carried out to visualize hilar basal dendrite or hilar ectopic migration.Virus-transduced GFP signals were used to identify the mossy fiber sprouting from the newly generated neurons.The number of cells with aberrant integrations was compared using unpaired Student's t-test.Results The percentage of newborn neurons with aberrant dendritic morphology was (20.8±8.4)% at week 8 after SE.The percentage of BrdU+NeuN double labeled cells ectopically migrated into the hilus was (15.9 ± 7.4)%.At week 8 after SE,the chronically epileptic mice showed many GFP+ processes in the IML with the same axonal appearance and small mossy fiber bouton-like structures as those seen in the hilus.The number of newborn neurons with aberrant integrations in SE mice wassignificantly increased when compared with the control mice (P <0.05).Conclusion These data demonstrate the existence of aberrant integrations-hilar basal dendrites,hilar ectopic migration and mossy fiber sprouting in the DG-generated cells born 1 week before an SE insult.
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Objective To investigate the effects of low dose radiation on dendritic growth of newborn neurons in the hippocampus of young rat.Methods One month-old male rats were randomized into radiation group aind sham control group.Radiation group received whole brain irradiation at a single dose of 2 Gy.Retrovirus expressing green fluorescent protein (GFP) was used to label newborn neurons in the hippocampus through stereotaxic intracranial infusion.Immunofluorescence assays were performed to detect dendritic architecture alterations induced by irradiation at different time points.Results Compared with control group,the lengths of total dendrite and the longest dendrite significantly decreased at 2 and 4 weeks after irradiation (t =3.10,2.07,2.94,4.02,P ＜ 0.05).The branching points of new born neurons were also decreased significantly at 2 weeks post irradiation (t =2.23,P ＜ 0.05).The number of new born neurons reduced at 4 weeks post irradiation (t =8.43,P ＜ 0.05).Conclusions Low dose radiation could inhibit newborn neuron growth in the hippocampus of young rat,which may be one of the most important mechanisms involved in radiation-induced cognitive impairment.
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Objective To investigate the effects of sevoflurane ( Sevo ) on dendritic development and the expression of collapsin response mediator proteins ( CRMP ) in the hippocampus of developing rats. Methods Twenty-four neonatal Sprague Dawley (SD) rats at postnatal day 7 (P7) were randomly divided into control group or sevoflurane group ( 12 rat pups for each group) .Rats in the control group were exposed to air for 4 h,whereas rats in the sevoflurane group were exposed to 2.8%sevoflurane for 4 h.The hippocam-pus of some rats were collected,and the expressions of CRMP1,CRMP2 and CRMP4 proteins and phospho-rylation of CRMP2 protein at Ser522,Thr514 and Thr555 were detected by Western blot 6h after exposure ( n=6) .The rest rats were housed till P30,the expression of CRMP1,CRMP2 and CRMP4 proteins in the hip-pocampus were detected by Western blot ( n=6) and the morphology changes of dendrites in the dentate gy-rus ( DG) of hippocampal neurons were detected by Golgi-Cox Staining ( n=6) .Results The expression of CRMP1,CRMP2 and CRMP4 proteins of rats at P7 in the sevoflurane group was decreased by 35.0%( P=0.004) ,27.5%( P=0.015) and 12.0%( P=0.003) ,respectively,and the phosphorylation of CRMP2 pro-tein at Ser522 and Thr514 in the sevoflurane group were increased by 68.3%( P<0.01) ,74.5%( P<0.01) , respectively,6 h after exposure compared with control rats.However,the phosphorylation of CRMP2 protein at Thr555 was not significantly changed after sevoflurane exposure.At P30,both total dendrite length ( P=0.001) and the dendrites length at level 2 and 3 ( P=0.033, P<0.01,respectively) were shorter and the dendritic branching at 120,140 and 160 μm rings in Sholl analysis were less ( P=0.009, P=0.028, P=0.048,respectively) for rats in the sevoflurane group,compared with control rats.There were no significant changes at the expressions of CRMP1,CRMP2 and CRMP4 proteins.Conclusion Sevoflurane inhibits the development of dendrites in the hippocampal DG area of developing rats,which may be related to inhibition of CRMP1,CRMP2 and CRMP4 proteins expression and hyperphosphorylation of CRMP2 Ser522 and Thr514.
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MicroRNAs (miRNAs) are critical for both development and function of the central nervous system. Significant evidence suggests that abnormal expression of miRNAs is associated with neurodevelopmental disorders. MeCP2 protein is an epigenetic regulator repressing or activating gene transcription by binding to methylated DNA. Both loss-of-function and gain-of-function mutations in the MECP2 gene lead to neurodevelopmental disorders such as Rett syndrome, autism and MECP2 duplication syndrome. In this study, we demonstrate that miR-130a inhibits neurite outgrowth and reduces dendritic spine density as well as dendritic complexity. Bioinformatics analyses, cell cultures and biochemical experiments indicate that miR-130a targets MECP2 and down-regulates MeCP2 protein expression. Furthermore, expression of the wild-type MeCP2, but not a loss-of-function mutant, rescues the miR-130a-induced phenotype. Our study uncovers the MECP2 gene as a previous unknown target for miR-130a, supporting that miR-130a may play a role in neurodevelopment by regulating MeCP2. Together with data from other groups, our work suggests that a feedback regulatory mechanism involving both miR-130a and MeCP2 may serve to ensure their appropriate expression and function in neural development.
Subject(s)
Animals , Rats , Dendrites , Genetics , Metabolism , Dendritic Spines , Genetics , Metabolism , Down-Regulation , Physiology , Methyl-CpG-Binding Protein 2 , Genetics , MicroRNAs , Genetics , MetabolismABSTRACT
Objective: To investigate the effects of Gastrodiae rhizoma, a dried root of Gastrodia elata Blume, on proliferation and differentiation of human NSCs derived from embryonic stem cells. Methods: A 70% ethanol extract of Gastrodiae rhizoma (EEGR) was estimated with 4-hydroxybenzyl alcohol as a representative constituent by HPLC. Results: MTT assay showed that the treatment with EEGR increased the viability of NSCs in growth media. Compared to control, EEGR increased the number of dendrites and denritic spines extended from a differentiated NSC. Whereas EEGR decreased the mRNA expression of Nestin, it increased that of Tuj1 and MAP2 in NSCs grown in differentiation media. Immunocytochemical analysis using confocal microscopy also revealed the increased expression of MAP2 in dendrites of EEGR-treated NSCs. Furthermore, EEGR decreased mRNA expression of Sox2 in NSCs grown even in growth media. Conclusions: In conclusion, our study demonstrates for the first time that EEGR induced proliferation and neuronal differentiation of NSCs, suggesting its potential benefits on NSC-based therapies and neuroregeneration in various neurodegenerative diseases and brain injuries.
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OBJECTIVE@#To investigate the effects of Gastrodiae rhizoma, a dried root of Gastrodia elata Blume, on proliferation and differentiation of human NSCs derived from embryonic stem cells.@*METHODS@#A 70% ethanol extract of Gastrodiae rhizoma (EEGR) was estimated with 4-hydroxybenzyl alcohol as a representative constituent by HPLC.@*RESULTS@#MTT assay showed that the treatment with EEGR increased the viability of NSCs in growth media. Compared to control, EEGR increased the number of dendrites and denritic spines extended from a differentiated NSC. Whereas EEGR decreased the mRNA expression of Nestin, it increased that of Tuj1 and MAP2 in NSCs grown in differentiation media. Immunocytochemical analysis using confocal microscopy also revealed the increased expression of MAP2 in dendrites of EEGR-treated NSCs. Furthermore, EEGR decreased mRNA expression of Sox2 in NSCs grown even in growth media.@*CONCLUSIONS@#In conclusion, our study demonstrates for the first time that EEGR induced proliferation and neuronal differentiation of NSCs, suggesting its potential benefits on NSC-based therapies and neuroregeneration in various neurodegenerative diseases and brain injuries.
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Autophagy,an intracellular d egradative pathway,mediates the degradation of long-lived proteins and some cellular organelles and thus plays crucial physiological role in the maintenance of neuronal homeostatsis. The intracellular and extracellular accumulation of protein aggregates is a common pathological alternation in various neurodegenerative disorders. The long and thin axons and dendrites (or collectively “neurites”) are particularly vulnerable to the accumulation of protein aggregates and damaged cellular organelles. Synaptic damage,axonal terminal degeneration,and neuritic atrophy are frequently found in the early stage of neurodegenerative diseases. Therefore, efficient clearance of protein aggregates and damaged cellular organelles by autophagic pathway may suppress neuritic degeneration. However, it is also demonstrated that insufficient autophagy or excessive autophagic activation contributes to neuritic injury. Here,the recent advances in the study of neuritic autophagy have been reviewed. We firstly introduce the biogenesis and transport of autophagosomes in neurites. Secondly,the regulatory role of autophagy in neuritic growth and damage is reviewed. Finally,the association between autophagy and neurodegenerative diseases is discussed.
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Stress exerts profound effects on cognitive and emotional functions. As a regulator of response to stress, the corticotropin releasing factor (CRF) during stress impacts organism function through hypothalamic-pituitary-adrenal axis. Recent research has shown that dendritic branches were abnormal and dendritic spine was lost under stress. In contrast, stressed mice with CRF receptor 1 (CRFR1) deficiency or CRFR1 antagonist exhibited normal dendritic morphology of hippocampal neurons. The structure and related factors expression of hippocampal neurons were affected by CRFR1 as a G protein-coupled receptor (GPCR), but the molecular mechanism about CRF-induced direct injury effect on hippocampal neurons has been poorly understood. The paper reviews the research progress on the contribution of stress activated CRF-CRF receptor signaling to the structure and related factors of hippocampal neurons.
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Stress exerts profound effects on cognitive and emotional functions. As a regulator of response to stress,the corticotropin releasing factor (CRF) during stress impacts organism function through hypothalamic-pituitary-adrenal axis. Recent research has shown that dendritic branches were abnormal and dendritic spine was lost under stress. In contrast,stressed mice with CRF receptor 1 (CRFR1) deficiency or CRFR1 antagonist exhibited normal dendritic morphology of hippocampal neurons .The structure and related factors expression of hippocampal neurons were affected by CRFR1 as a G protein-coupled receptor(GPCR), but the molecular mechanism about CRF-induced direct injury effect on hippocampal neurons has been poorly understood. The paper reviews the research progress on the contribution of stress activated CRF-CRF receptor signaling to the structure and related factors of hippocampal neurons.
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Objective To explore whether phenylalanine affect Cdc42, Racl, and RhoA expression and disturb dendritic development. To determine the effects of brain-derived neurotrophic factor (BDNF) on this process. Methods Neurons were cultivated up to 3 days and then treated with 0.9 mmol/L phenylalanine or 100 ng/ml BDNF. Dendritic number were determined by morphologic analysis. Cdc42, Racl, and RhoA protein expression were examined by Western blotting analysis. ResultsThe number of dendrites in cultured neurons reduced two days after being treated with phenylalanine,while BDNF could rescue this change(P < 0.01), furthermore, BDNF was found to inhibit phenylalanineinduced down-regulation of Cdc42, Racl, and RhoA protein expression(P < 0.01). Conclusions Our study indicated that the protective effect of BDNF against phenylalanine-induced neuronal injury is probably mediated by expression of Cdc42, Racl,and RhoA. It suggested a potential neuroprotective action of BDNF in prevention and treatment of brain injury in the patients with phenylketonuria.
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Objective To investigate the effects of glutamate receptor signaling on melanoma cell dendrite morphology and cytoskeleton protein. Methods A metastatic human malignant melanoma cell line WM451LU was cultured and transfected by recombinant adenovirus vector carrying a cDNA encoding microtubule-associated protein 2a (MAP2a). MK-801, an antagonist of N-methyl-D-aspartate receptor (NMDAR), and CPCCOEt, an antagonist of metabotropie glutamate receptor 1 (mGluR1), were used to treat transfected or untrausfeeted WM451LU cells. Confocal microscopy and three dimensional atomic force microscopy were used to assess subcellular location of NMDAR2A, mGluR1 and MAP2a as well as the dis-tribution of α-tubulin in and dendrite morphology of WM451LU cells. The proliferation of WM451LU cells was estimated by cell survival growth curve. Results Confocal laser microscopy revealed that NMDAR2A, mGluRl and MAP2a were mainly co-localized in melanoma cell dendrites. Both MK-801 and CPCCOEt increased the density of microtubules in cell dendrites and dendritic branching of WM451LU cells, and both effects of MK-801 and CPCCOEt were enhanced by the expression of MAP2a. Furthermore, the proliferation of WM451LU cells was significantly inhibited by MK-801 of 100 μmol/L and CPCCOEt of 10 μmol/L. Conclusions In melanoma cells, glutamate receptors may participate in the development of dendrites, and anta- gonists of glutamate receptors could inhibit the proliferation of melanoma cells.
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γ-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the adult brain. However, electrophysiological findings indicate that GABA exerts excitation in dendrites of mature eorlieal neurons. Little is known about morphological basis of GABA-medi-ated excitation in dendrites of mature cortical neurons. The effect of activated GABAA receptors is mainly determined by intraceUular chloride ion, whose active influx is mainly mediated by Na+-K +-Cl- cotransporter isoform 1 (NKCC1) and exclusion is mainly executed by K+-Cl- cotransporter isoform 2 ( KCC2 ). In the present study, by using immunofluorescent double staining and fluorescent density analysis, the expression and distribution of NKCCI- and KCC2-immunoreactivities in the dendrite and soma of adult rat neocortical neurons were detected in vivo and in vitro. The present results showed that both cytoplasm and membrane of neuronal soma and dendrite expressed NKCC1, while KCC2 only expressed in membrane of soma and dendrite. The results also indicated that the dendrites rather than the somata of neurons expressed more NKCC1 in adult rat neocortex, while the level of KCC2 expression in the dendrite membrane was similar to that in the membrane of somata. The similar expression pattern of NKCC1 and KCC2 in the dendrites and the somata was also observed in neocortical neurons cultured for 20 days in vitro. The present results suggest that the more NKCC1 expreasion in dendrites may contribute to GABA-mediated excitation in neuronal dendrites of adult neocortex neurons.
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It has been known that the Alzheimer's disease(AD)is related closely with a synaptic failure,and the p21-activated kinase(PAK)is well documented to play an important role in the regulation of the synaptie functions.However,the relationship between thePAK and the pathology of AD is unclear.In the present study,we examined the expressions of the PAK3(one subtype ofPAK),phospho-rylated-PAK(pPAK) and β-amyloid42(Aβ42,β-amyloid with 42 peptides)in an APP/PS1 double transgenie mouse model of AD andthe morphologies of geurOtlS in the hippocampus at different ages.The Western Blot results showed that the expression of PAK remainedunchanged,while,the expression of pPAK decreased largely at the age of 32 weeks and further decreased significantly with aging in thehippocampus of the APP/PS1 transgenic mouse.A1342 levels in the hippocampus were detected to increase as early as the age of 22 weeks,and kept the increase to continue with aging.The morphological results showed no obvious neuron loss in the sections of Nissl staining,while serious distonion and disorder of the dendrites of the hippocampal neurons were observed on the sections of Gelgi staining in theAPP/PS1 transgenic mouse.The present results suggested that it seemed something wrong in the processes of phospholization of PAK,butnot in the expression of the PAK itself;the toxic Aβ42 might affect the PAK in its phospholization,which in turn directly influence thedendritic development in the hippocampal neurons and cause the dendrites distorting and disordering.