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1.
Anat Sci Int ; 2024 Jul 31.
Artículo en Inglés | MEDLINE | ID: mdl-39085683

RESUMEN

Approaches for the induction of neurogenesis and neuronal recovery through several modalities are gaining popularity in Parkinson's disease (PD). Growth hormone (GH) seems to have a role in the reversal of neural function following brain injury as well as in normal brain development and function; therefore, the use of GH may represent a feasible strategy in the management of PD. This experimental study aimed to evaluate the effect of growth hormone on motor function and dendrite morphology in rats with 6-hydroxydopamine (6-OHDA)-induced PD model. Thirty-six Sprague Dawley rats were included and randomly allocated into one of the six study groups: two controls and four treatment groups that received daily subcutaneous growth hormone injections for 21 days, 1, 2, and 3 months. PD model was induced through unilateral 6-OHDA injection to the nigrostriatal pathway. The following assessments were made: apomorphine rotation test, stepping test, and tissue examinations for tyrosine hydroxylase and dendrite morphology. The apomorphine rotation test and the stepping test confirmed the presence of PD. These tests as well as dendritic spine density/number and length assessments showed improvement in PD findings over time with GH administration. Findings of this study suggest that GH administration may improve dendrite morphology and motor function in the PD model, which may translate into symptom relief and quality of life improvement in patients with PD. Such potential benefits should be tested in robust clinical studies.

2.
Int J Mol Sci ; 25(12)2024 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-38928447

RESUMEN

Exposure to general anesthetics can adversely affect brain development, but there is little study of sedative agents used in intensive care that act via similar pharmacologic mechanisms. Using quantitative immunohistochemistry and neurobehavioral testing and an established protocol for murine sedation, we tested the hypothesis that lengthy, repetitive exposure to midazolam, a commonly used sedative in pediatric intensive care, interferes with neuronal development and subsequent cognitive function via actions on the mechanistic target of rapamycin (mTOR) pathway. We found that mice in the midazolam sedation group exhibited a chronic, significant increase in the expression of mTOR activity pathway markers in comparison to controls. Furthermore, both neurobehavioral outcomes, deficits in Y-maze and fear-conditioning performance, and neuropathologic effects of midazolam sedation exposure, including disrupted dendritic arborization and synaptogenesis, were ameliorated via treatment with rapamycin, a pharmacologic mTOR pathway inhibitor. We conclude that prolonged, repetitive exposure to midazolam sedation interferes with the development of neural circuitry via a pathologic increase in mTOR pathway signaling during brain development that has lasting consequences for both brain structure and function.


Asunto(s)
Midazolam , Transducción de Señal , Serina-Treonina Quinasas TOR , Midazolam/farmacología , Animales , Serina-Treonina Quinasas TOR/metabolismo , Ratones , Transducción de Señal/efectos de los fármacos , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Encéfalo/patología , Masculino , Hipnóticos y Sedantes/farmacología , Conducta Animal/efectos de los fármacos , Femenino , Ratones Endogámicos C57BL , Aprendizaje por Laberinto/efectos de los fármacos , Animales Recién Nacidos
3.
Brain ; 147(9): 3171-3188, 2024 Sep 03.
Artículo en Inglés | MEDLINE | ID: mdl-38478593

RESUMEN

Full-length RIM1 and 2 are key components of the presynaptic active zone that ubiquitously control excitatory and inhibitory neurotransmitter release. Here, we report that the function of the small RIM isoform RIM4, consisting of a single C2 domain, is strikingly different from that of the long isoforms. RIM4 is dispensable for neurotransmitter release but plays a postsynaptic, cell type-specific role in cerebellar Purkinje cells that is essential for normal motor function. In the absence of RIM4, Purkinje cell intrinsic firing is reduced and caffeine-sensitive, and dendritic integration of climbing fibre input is disturbed. Mice lacking RIM4, but not mice lacking RIM1/2, selectively in Purkinje cells exhibit a severe, hours-long paroxysmal dystonia. These episodes can also be induced by caffeine, ethanol or stress and closely resemble the deficits seen with mutations of the PNKD (paroxysmal non-kinesigenic dystonia) gene. Our data reveal essential postsynaptic functions of RIM proteins and show non-overlapping specialized functions of a small isoform despite high homology to a single domain in the full-length proteins.


Asunto(s)
Células de Purkinje , Animales , Células de Purkinje/metabolismo , Ratones , Ratones Noqueados , Proteínas de Unión al GTP/genética , Proteínas de Unión al GTP/metabolismo , Ratones Endogámicos C57BL , Cerebelo/metabolismo , Distonía/genética , Distonía/fisiopatología
4.
Materials (Basel) ; 16(9)2023 Apr 27.
Artículo en Inglés | MEDLINE | ID: mdl-37176292

RESUMEN

Single crystal superalloys are widely used in the manufacturing of turbine blades for aero-engines due to their superior performance at high temperatures. The directional solidification process is a key technology for producing single crystal turbine blades with excellent properties. In the directional solidification process, withdrawal rate is one of the critical parameters for microstructure formation and will ultimately determine the blade's properties. In this paper, the as-cast microstructures in the typical sections of a DD9 single crystal (SX) superalloy turbine blade were investigated with 3 mm/min and 5 mm/min withdrawal rates during the directional solidification process. With increased withdrawal rate, the dendrite morphologies tended to become more refined, and the secondary dendritic arms tended to be highly developed. The dendrite in the blade aerofoil section was more refined than that in the tenon section, given the same withdrawal rate. Additionally, with increasing withdrawal rates, the size and dispersity of the γ' precipitates in the inter-dendritic (ID) regions and dendritic core (DC) tended to decrease; furthermore, the size distributions of the γ' precipitates followed a normal distribution law. Compared with the ID regions, an almost 62% reduction in the average γ' sizes was measured in the DC. Meanwhile, given the same withdrawal rate, at the blade's leading edge closest to the heater, the γ' sizes in the aerofoil section (AS) were more refined than those in the tenon section (TS). As compared with the decreasing cross-sectional areas, the increased withdrawal rates clearly brought down the γ' sizes. The sizes of the γ-γ' eutectics decreased with increasing withdrawal rates, with the γ-γ' eutectics showing both lamellar and rosette shapes.

5.
Chemosphere ; 305: 135461, 2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-35764107

RESUMEN

Monoclinic BiVO4 (m-BiVO4) has been reported as promising phase for solar light driven photocatalysis. However, in the case of morphology guided BiVO4 with different synthetic conditions maintaining the m-BiVO4 phase remains a substantial challenge for achieving an efficient photocatalyst driven by solar light. Herein, a simple hydrothermal approach was used to produce well-defined template free m-BiVO4 dendrites with distinct branches for photo catalytically removal of organic pollutant and photocurrent generation. The development of monoclinic dendrite BiVO4 was confirmed after comprehensive structural, morphological, and optical examinations. FE-SEM images of m-BiVO4 revealed transformation of spherical to dendritic morphology with distinct branches by simply changing the HNO3 to NaOH ratios from 2:1 to 2:2, which are named as BVO 2-1 and BVO 2-2, respectively. The BVO 2-2 dendrites exhibited improved activity of 98% towards methylene blue (MB) photodegradation upon simulated solar light irradiation. The BVO 2-2 dendrites photoelectrode showed an outstanding photocurrent density of 1.4245 mAcm-2 than that of the BVO 2-1 spherical photoelectrode (0.7367 mAcm-2). Enhanced photocatalytic and photoelectrochemical action, could be ascribed to the unique morphological changes provides photoactive sites, harvest more light utilization together with higher separation of e-/h+ pairs. Furthermore, photocatalytic mechanism is investigated based on scavenger trapping agent, valence band XPS, UV Visible DRS and PL study. Our findings could pave the way for the development of dendritic nanostructure photocatalysts with improved photocatalytic activity.


Asunto(s)
Contaminantes Ambientales , Vanadatos , Bismuto/química , Catálisis , Dendritas , Luz , Vanadatos/química
6.
Adv Sci (Weinh) ; 9(12): e2105574, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-35212469

RESUMEN

Li is an ideal anode material for use in state-of-the-art secondary batteries. However, Li-dendrite growth is a safety concern and results in low coulombic efficiency, which significantly restricts the commercial application of Li secondary batteries. Unfortunately, the Li-deposition (growth) mechanism is poorly understood on the atomic scale. Here, machine learning is used to construct a Li potential model with quantum-mechanical computational accuracy. Molecular dynamics simulations in this study with this model reveal two self-healing mechanisms in a large Li-metal system, viz. surface self-healing, and bulk self-healing. It is concluded that self-healing occurs rapidly in nanoscale; thus, minimizing the voids between the Li grains using several comprehensive methods can effectively facilitate the formation of dendrite-free Li.

7.
Cell Mol Neurobiol ; 42(5): 1399-1417, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33392918

RESUMEN

Brain-derived neurotrophic factor (BDNF) and neurotrophin 3 (NT-3) are known to regulate neuronal morphology and the formation of neural circuits, yet the neuronal targets of each neurotrophin are still to be defined. To address how these neurotrophins regulate the morphological and synaptic differentiation of developing olfactory bulb (OB) GABAergic interneurons, we analyzed the effect of BDNF and NT-3 on GABA+-neurons and on different subtypes of these neurons: tyrosine hydroxylase (TH+); calretinin (Calr+); calbindin (Calb+); and parvalbumin (PVA+). These cells were generated from cultured embryonic mouse olfactory bulb neural stem cells (eOBNSCs) and after 14 days in vitro (DIV), when the neurons expressed TrkB and/or TrkC receptors, BDNF and NT-3 did not significantly change the number of neurons. However, long-term BDNF treatment did produce a longer total dendrite length and/or more dendritic branches in all the interneuron populations studied, except for PVA+-neurons. Similarly, BDNF caused an increase in the cell body perimeter in all the interneuron populations analyzed, except for PVA+-neurons. GABA+- and TH+-neurons were also studied at 21 DIV, when BDNF produced significantly longer neurites with no clear change in their number. Notably, these neurons developed synaptophysin+ boutons at 21 DIV, the size of which augmented significantly following exposure to either BDNF or NT-3. Our results show that in conditions that maintain neuronal survival, BDNF but not NT-3 promotes the morphological differentiation of developing OB interneurons in a cell-type-specific manner. In addition, our findings suggest that BDNF and NT-3 may promote synapse maturation by enhancing the size of synaptic boutons.


Asunto(s)
Factor Neurotrófico Derivado del Encéfalo , Neurotrofina 3 , Animales , Factor Neurotrófico Derivado del Encéfalo/farmacología , Células Cultivadas , Dendritas/metabolismo , Interneuronas/metabolismo , Ratones , Proteínas del Tejido Nervioso/metabolismo , Neurotrofina 3/farmacología , Bulbo Olfatorio , Terminales Presinápticos/metabolismo , Ácido gamma-Aminobutírico
8.
Neurobiol Stress ; 15: 100381, 2021 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-34458512

RESUMEN

Converging clinical and preclinical evidence demonstrates that depressive phenotypes are associated with synaptic dysfunction and dendritic simplification in cortico-limbic glutamatergic areas. On the other hand, the rapid antidepressant effect of acute ketamine is consistently reported to occur together with the rescue of dendritic atrophy and reduction of spine number induced by chronic stress in the hippocampus and prefrontal cortex of animal models of depression. Nevertheless, the molecular mechanisms underlying these morphological alterations remain largely unknown. Here, we found that miR-9-5p levels were selectively reduced in the hippocampus of rats vulnerable to Chronic Mild Stress (CMS), while acute subanesthetic ketamine restored its levels to basal condition in just 24h; miR-9-5p expression inversely correlated with the anhedonic phenotype. A decrease of miR-9-5p was reproduced in an in vitro model of stress, based on primary hippocampal neurons incubated with the stress hormone corticosterone. In both CMS animals and primary neurons, decreased miR-9-5p levels were associated with dendritic simplification, while treatment with ketamine completely rescued the changes. In vitro modulation of miR-9-5p expression showed a direct role of miR-9-5p in regulating dendritic length and spine density in mature primary hippocampal neurons. Among the putative target genes tested, Rest and Sirt1 were validated as biological targets in primary neuronal cultures. Moreover, in line with miR-9-5p changes, REST protein expression levels were remarkably increased in both CMS vulnerable animals and corticosterone-treated neurons, while ketamine completely abolished this alteration. Finally, the shortening of dendritic length in corticosterone-treated neurons was shown to be partly rescued by miR-9-5p overexpression and dependent on REST protein expression. Overall, our data unveiled the functional role of miR-9-5p in the remodeling of dendritic arbor induced by stress/corticosterone in vulnerable animals and its rescue by acute antidepressant treatment with ketamine.

9.
Dev Neurobiol ; 81(6): 774-785, 2021 09.
Artículo en Inglés | MEDLINE | ID: mdl-34114331

RESUMEN

Leucine-rich repeat (LRR) transmembrane proteins have been directly linked to neurodevelopmental and cognitive disorders. We have previously shown that the LRR transmembrane protein, leucine-rich repeats and immunoglobulin-like domains 1 (Lrig1), is a physiological regulator of dendrite complexity of hippocampal pyramidal neurons and social behavior. In this study, we performed a battery of behavioral tests to evaluate spatial memory and cognitive capabilities in Lrig1 mutant mice. The cognitive assessment demonstrated deficits in recognition and spatial memory, evaluated by novel object recognition and object location tests. Moreover, we found that Lrig1-deficient mice present specific impairments in the processing of similar but not dissimilar locations in a spatial pattern separation task, which was correlated with an enhanced dendritic growth and branching of Doublecortin-positive immature granule cells of the dentate gyrus. Altogether, these findings indicate that Lrig1 plays an essential role in controlling morphological and functional plasticity in the hippocampus.


Asunto(s)
Cognición , Hipocampo , Animales , Cognición/fisiología , Dendritas/metabolismo , Hipocampo/metabolismo , Dominios de Inmunoglobulinas , Leucina/metabolismo , Ratones
10.
Cells ; 9(11)2020 11 09.
Artículo en Inglés | MEDLINE | ID: mdl-33182316

RESUMEN

The classical motor symptoms of Parkinson's disease (PD) are caused by degeneration of dopaminergic neurons in the substantia nigra, which is followed by secondary dendritic pruning and spine loss at striatal medium spiny neurons (MSN). We hypothesize that these morphological changes at MSN underlie at least in part long-term motor complications in PD patients. In order to define the potential benefits and limitations of dopamine substitution, we tested in a mouse model whether dendritic pruning and spine loss can be reversible when dopaminergic axon terminals regenerate. In order to induce degeneration of nigrostriatal dopaminergic neurons we used the toxicity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in C57BL/6J mice; 30 mg/kg MPTP was applied i.p. on five consecutive days. In order to assess the consequences of dopamine depletion, mice were analyzed 21 days after the last injection. In order to test reversibility of MSN changes we exploited the property of this model that striatal axon terminals regenerate by sprouting within 90 days and analyzed a second cohort 90 days after MPTP. Degeneration of dopaminergic neurons was confirmed by counting TH-positive neurons in the substantia nigra and by analyzing striatal catecholamines. Striatal catecholamine recovered 90 days after MPTP. MSN morphology was visualized by Golgi staining and quantified as total dendritic length, number of dendritic branch points, and density of dendritic spines. All morphological parameters of striatal MSN were reduced 21 days after MPTP. Statistical analysis indicated that dendritic pruning and the reduction of spine density represent two distinct responses to dopamine depletion. Ninety days after MPTP, all morphological changes recovered. Our findings demonstrate that morphological changes in striatal MSN resulting from dopamine depletion are reversible. They suggest that under optimal conditions, symptomatic dopaminergic therapy might be able to prevent maladaptive plasticity and long-term motor complications in PD patients.


Asunto(s)
Cuerpo Estriado/citología , Dopamina/deficiencia , Neuronas/citología , 1-Metil-4-fenil-1,2,3,6-Tetrahidropiridina , Animales , Axones/metabolismo , Espinas Dendríticas/metabolismo , Modelos Animales de Enfermedad , Modelos Lineales , Ratones Endogámicos C57BL , Fenotipo
11.
Materials (Basel) ; 13(10)2020 May 22.
Artículo en Inglés | MEDLINE | ID: mdl-32455932

RESUMEN

The effects of solute element content and cooling rate on the morphology of Al6Mn phase in suction casting Al-Mn alloys were investigated by transmission electron microscope, scanning electron microscope, and X-ray diffractometer. Results show that Al6Mn dendrite morphology with different degrees of development can occur in the microstructure of as-cast Al-Mn alloys. For the Al-4 wt.% Mn alloy, there are small amounts of block Al6Mn crystals at the center of sample, while we see a block Al6Mn phase and a feathery Al6Mn phase in the sample of Al-6 wt.% Mn alloy. Moreover, the block Al6Mn phases in the Al-8 wt.% Mn alloy disappear, and only snowflake-like Al6Mn phases play a dominant role in the microstructure. However, with an increase in Mn content to 10 wt.%, more dendritic trunks are formed, and secondary dendrite arms are degraded more seriously due to the formation of an icosahedral quasicrystal in suction casting. In addition to the effect of Mn content on Al6Mn morphology, with the increase in cooling rate from the center to the edge of samples, the outline diameter of equiaxed dendrite decreases. The evolution of Al6Mn dendrite morphology and the formation of quasicrystal are further discussed.

12.
ACS Appl Mater Interfaces ; 11(51): 47878-47885, 2019 Dec 26.
Artículo en Inglés | MEDLINE | ID: mdl-31769958

RESUMEN

There is a growing demand for higher energy density lithium batteries. One approach for addressing this demand is enabling lithium metal anodes. However, nucleation and growth of electronically conductive protrusions, which cause short circuits, prevent the use of this technology with liquid electrolytes. The use of rigid solid electrolytes such as polystyrene-b-poly(ethylene oxide) electrolytes is one solution. An additional requirement for practical cells is needed to use electrolytes with high salt concentration to maximize the flux of lithium ions in the cell. The first systematic study of the effect of salt concentration on the morphology of electrodeposited lithium through a rigid block copolymer electrolyte is presented. The nature, areal density, and morphologies of defective lithium deposits created during galvanostatic cycling of lithium-lithium symmetric cells were determined using hard X-ray microtomography. Cycle life decreases rapidly with increasing salt concentration. X-ray microtomography reveals the presence of multiglobular protrusions, which are nucleated at impurity particles at low salt concentrations; here, the areal density of defective lithium deposits was independent of salt concentration. At the highest salt concentration, this density increases abruptly by a factor of about 10, and defects were also nucleated at locations where no impurities were visible.

13.
J Cell Sci ; 132(20)2019 10 18.
Artículo en Inglés | MEDLINE | ID: mdl-31548203

RESUMEN

Autism spectrum disorders (ASDs) are neurodevelopmental disorders with multiple genetic associations. Analysis of de novo mutations identified GRIN2B, which encodes the GluN2B subunit of NMDA receptors, as a gene linked to ASDs with high probability. However, the mechanisms by which GRIN2B mutations contribute to ASD pathophysiology are not understood. Here, we investigated the cellular phenotypes induced by a human mutation that is predicted to truncate GluN2B within the extracellular loop. This mutation abolished NMDA-dependent Ca2+ influx. Mutant GluN2B co-assembled with GluN1 but was not trafficked to the cell surface or dendrites. When mutant GluN2B was expressed in developing cortical neurons, dendrites appeared underdeveloped, with shorter and fewer branches, while spine density was unaffected. Mutant dendritic arbors were often dysmorphic, displaying abnormal filopodial-like structures. Interestingly, dendrite maldevelopment appeared when mutant GluN2B was expressed on a wild-type background, reflecting the disease given that individuals are heterozygous for GRIN2B mutations. Restoring the fourth transmembrane domain and cytoplasmic tail did not rescue the phenotypes. Finally, abnormal development was not accompanied by reduced mTOR signaling. These data suggest that mutations in GluN2B contribute to ASD pathogenesis by disrupting dendrite development.


Asunto(s)
Trastorno del Espectro Autista , Señalización del Calcio , Dendritas/metabolismo , Mutación , Receptores de N-Metil-D-Aspartato , Trastorno del Espectro Autista/genética , Trastorno del Espectro Autista/metabolismo , Trastorno del Espectro Autista/patología , Dendritas/patología , Células HEK293 , Humanos , Transporte de Proteínas/genética , Receptores de N-Metil-D-Aspartato/genética , Receptores de N-Metil-D-Aspartato/metabolismo , Serina-Treonina Quinasas TOR/genética , Serina-Treonina Quinasas TOR/metabolismo
14.
J Cell Sci ; 132(13)2019 07 05.
Artículo en Inglés | MEDLINE | ID: mdl-31189538

RESUMEN

Protein palmitoylation is the most common post-translational lipid modification in the brain and is mediated by a family of 24 zDHHC enzymes. There has been growing interest in zDHHCs due to mounting evidence that these enzymes play key roles in the development and function of neuronal connections, and the fact that a number of zDHHCs have been associated with neurodevelopmental and neurodegenerative diseases. Loss-of-function variants in several zDHHCs, including zDHHC15, have been identified in patients with intellectual disabilities; however, the function of zDHHC15 in the brain has not been well studied. Here, we demonstrate that knocking down zDHHC15 in primary rat hippocampal cultures reduces dendritic outgrowth and arborization, as well as spine maturation. Moreover, knockdown of zDHHC15 reduces palmitoylation of PSD-95 and its trafficking into dendrites, resulting in an overall decrease in the density of excitatory synapses being formed onto mutant cells.


Asunto(s)
Aciltransferasas/fisiología , Proteínas de Unión al ADN/metabolismo , Dendritas/metabolismo , Sinapsis/metabolismo , Aciltransferasas/genética , Animales , Espinas Dendríticas/metabolismo , Homólogo 4 de la Proteína Discs Large/metabolismo , Aparato de Golgi/metabolismo , Células HEK293 , Hipocampo/metabolismo , Humanos , Ratones , Ratas Sprague-Dawley
15.
Development ; 146(7)2019 04 05.
Artículo en Inglés | MEDLINE | ID: mdl-30890568

RESUMEN

The generation of neuronal diversity is essential for circuit formation and behavior. Morphological differences in sequentially born neurons could be due to intrinsic molecular identity specified by temporal transcription factors (henceforth called intrinsic temporal identity) or due to changing extrinsic cues. Here, we have used the Drosophila NB7-1 lineage to address this issue. NB7-1 generates the U1-U5 motor neurons sequentially; each has a distinct intrinsic temporal identity due to inheritance of different temporal transcription factors at its time of birth. We show that the U1-U5 neurons project axons sequentially, followed by sequential dendrite extension. We misexpressed the earliest temporal transcription factor, Hunchback, to create 'ectopic' U1 neurons with an early intrinsic temporal identity but later birth-order. These ectopic U1 neurons have axon muscle targeting and dendrite neuropil targeting that are consistent with U1 intrinsic temporal identity, rather than with their time of birth or differentiation. We conclude that intrinsic temporal identity plays a major role in establishing both motor axon muscle targeting and dendritic arbor targeting, which are required for proper motor circuit development.


Asunto(s)
Axones/metabolismo , Proteínas de Unión al ADN/metabolismo , Dendritas/metabolismo , Proteínas de Drosophila/metabolismo , Factores de Transcripción/metabolismo , Animales , Proteínas de Unión al ADN/genética , Drosophila , Proteínas de Drosophila/genética , Regulación del Desarrollo de la Expresión Génica , Neuronas Motoras , Factores de Transcripción/genética
16.
Elife ; 82019 03 28.
Artículo en Inglés | MEDLINE | ID: mdl-30920370

RESUMEN

Class IV ddaC neurons specifically prune larval dendrites without affecting axons during Drosophila metamorphosis. ddaCs distribute the minus ends of microtubules (MTs) to dendrites but the plus ends to axons. However, a requirement of MT minus-end-binding proteins in dendrite-specific pruning remains completely unknown. Here, we identified Patronin, a minus-end-binding protein, for its crucial and dose-sensitive role in ddaC dendrite pruning. The CKK domain is important for Patronin's function in dendrite pruning. Moreover, we show that both patronin knockdown and overexpression resulted in a drastic decrease of MT minus ends and a concomitant increase of plus-end-out MTs in ddaC dendrites, suggesting that Patronin stabilizes dendritic minus-end-out MTs. Consistently, attenuation of Klp10A MT depolymerase in patronin mutant neurons significantly restored minus-end-out MTs in dendrites and thereby rescued dendrite-pruning defects. Thus, our study demonstrates that Patronin orients minus-end-out MT arrays in dendrites to promote dendrite-specific pruning mainly through antagonizing Klp10A activity. Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that minor issues remain unresolved (see decision letter).


Asunto(s)
Proteínas de Drosophila/metabolismo , Drosophila melanogaster/fisiología , Proteínas Asociadas a Microtúbulos/metabolismo , Microtúbulos/metabolismo , Plasticidad Neuronal , Animales , Cinesinas/metabolismo
17.
J Neurotrauma ; 36(13): 2129-2138, 2019 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-30747034

RESUMEN

Postsynaptic density 95 (PSD-95), the major scaffold protein at excitatory synapses, plays a major role in mediating intracellular signaling by synaptic N-methyl-d-aspartate (NMDA) type glutamate receptors. Despite the fact that much is known about the role of PSD-95 in NMDA-mediated toxicity, less is known about its role in mechanical injury, and more specifically, in traumatic brain injury (TBI). Given that neural circuitry is disrupted after TBI and that PSD-95 and its interactors end-binding protein 3 (EB3) and adenomatous polyposis coli (APC) shape dendrites, we examined whether changes to these proteins and their interactions occur after brain trauma. Here, we report that total levels of PSD-95 and the interaction of PSD-95 with EB3 increase at 1 and 7 days after moderate controlled cortical impact (CCI), but these changes do not occur after mild injury. Because changes occur to PSD-95 following brain trauma in vivo, we next considered the functional consequences of PSD-95 alterations in vitro. Rapid deformation of cortical neurons leads to neuronal death 72 h after injury, but this outcome is not dependent on PSD-95 expression. However, disruptions in dendritic arborization following stretch injury in vitro require PSD-95 expression, and these changes in arborization can be mimicked with expression of PSD-95 mutants lacking the second PDZ domain. Thus, PSD-95 and its interactors may serve as therapeutic targets for repairing dendrites after TBI.


Asunto(s)
Proteína de la Poliposis Adenomatosa del Colon/metabolismo , Conmoción Encefálica/metabolismo , Lesiones Traumáticas del Encéfalo/metabolismo , Homólogo 4 de la Proteína Discs Large/metabolismo , Proteínas Asociadas a Microtúbulos/metabolismo , Animales , Conmoción Encefálica/patología , Lesiones Traumáticas del Encéfalo/patología , Modelos Animales de Enfermedad , Masculino , Ratones , Ratones Endogámicos C57BL
18.
Neuroscience ; 398: 23-36, 2019 02 01.
Artículo en Inglés | MEDLINE | ID: mdl-30496825

RESUMEN

Synaptic pruning during adolescence is critical for optimal cognition. The CA3 hippocampus contains unique spine types and plays a pivotal role in pattern separation and seizure generation, where sex differences exist, but adolescent pruning has only been studied in the male. Thus, for the present study we assessed pruning of specific spine types in the CA3 hippocampus during adolescence and investigated a possible mechanism in the female mouse. To this end, we used Golgi-impregnated brains from pubertal (∼PND 35, assessed by vaginal opening) and post-pubertal (PND 56) mice. Spine density was assessed from z-stack (0.1-µm steps) images taken using a Nikon DS-U3 camera through a Nikon Eclipse Ci-L microscope and analyzed with NIS Elements. Spine density decreased significantly (P < 0.05) during adolescence, with 50-60% decreases in mushroom and stubby spine-types (P < 0.05, ∼PND35 vs. PND56) in non-proestrous mice. This was associated with decreases in kalirin-7, a spine protein which stabilizes the cytoskeleton and is required for spine maintenance. Because our previous findings suggest that pubertal increases in α4ßδ GABAA receptors (GABARs) trigger pruning in CA1, we investigated their role in CA3. α4 expression in CA3 hippocampus increased 4-fold at puberty (P < 0.05), assessed by immunostaining and verified electrophysiologically by an increased response to gaboxadol (100 nM), which is selective for α4ßδ. Knock-out of α4 prevented the pubertal decrease in kalirin-7 and synaptic pruning and also increased the dendritic length, demonstrating a functional link. These data suggest that pubertal α4ßδ GABARs alter dendritic morphology and trigger pruning in female CA3 hippocampus.


Asunto(s)
Región CA3 Hipocampal/crecimiento & desarrollo , Dendritas/metabolismo , Plasticidad Neuronal/fisiología , Células Piramidales/metabolismo , Receptores de GABA-A/metabolismo , Animales , Región CA3 Hipocampal/citología , Región CA3 Hipocampal/metabolismo , Tamaño de la Célula , Femenino , Factores de Intercambio de Guanina Nucleótido/metabolismo , Ratones Endogámicos C57BL , Ratones Transgénicos , Células Piramidales/citología , Maduración Sexual , Técnicas de Cultivo de Tejidos
19.
J Neurosci ; 37(29): 6946-6955, 2017 07 19.
Artículo en Inglés | MEDLINE | ID: mdl-28626015

RESUMEN

Nuclear calcium is an important signaling end point in synaptic excitation-transcription coupling that is critical for long-term neuroadaptations. Here, we show that nuclear calcium acting via a target gene, VEGFD, is required for hippocampus-dependent fear memory consolidation and extinction in mice. Nuclear calcium-VEGFD signaling upholds the structural integrity and complexity of the dendritic arbor of CA1 neurons that renders those cells permissive for the efficient generation of synaptic input-evoked nuclear calcium transients driving the expression of plasticity-related genes. Therefore, the gating of memory functions rests on the reciprocally reinforcing maintenance of an intact dendrite geometry and a functional synapse-to-nucleus communication axis. In psychiatric and neurodegenerative disorders, therapeutic application of VEGFD may help to stabilize dendritic structures and network connectivity, which may prevent cognitive decline and could boost the efficacy of extinction-based exposure therapies.SIGNIFICANCE STATEMENT This study uncovers a reciprocal relationship between dendrite geometry, the ability to generate nuclear calcium transients in response to synaptic inputs, and the subsequent induction of expression of plasticity-related and dendritic structure-preserving genes. Insufficient nuclear calcium signaling in CA1 hippocampal neurons and, consequently, reduced expression of the nuclear calcium target gene VEGFD, a dendrite maintenance factor, leads to reduced-complexity basal dendrites of CA1 neurons, which severely compromises the animals' consolidation of both memory and extinction memory. The structure-protective function of VEGFD may prove beneficial in psychiatric disorders as well as neurodegenerative and aging-related conditions that are associated with loss of neuronal structures, dysfunctional excitation-transcription coupling, and cognitive decline.


Asunto(s)
Señalización del Calcio/fisiología , Núcleo Celular/fisiología , Dendritas/ultraestructura , Extinción Psicológica/fisiología , Consolidación de la Memoria/fisiología , Plasticidad Neuronal/fisiología , Factor D de Crecimiento Endotelial Vascular/metabolismo , Animales , Calcio , Dendritas/fisiología , Masculino , Recuerdo Mental/fisiología , Ratones , Ratones Endogámicos C57BL , Retención en Psicología/fisiología , Transducción de Señal/fisiología
20.
Protein Cell ; 7(7): 489-500, 2016 07.
Artículo en Inglés | MEDLINE | ID: mdl-27245166

RESUMEN

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.


Asunto(s)
Dendritas/metabolismo , Espinas Dendríticas/metabolismo , Regulación hacia Abajo/fisiología , Proteína 2 de Unión a Metil-CpG/biosíntesis , MicroARNs/metabolismo , Animales , Dendritas/genética , Espinas Dendríticas/genética , Proteína 2 de Unión a Metil-CpG/genética , MicroARNs/genética , Ratas
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