Papers by Froylan de Anda
Control of Axon Selection
eLS, 2001
DIXDC1 Phosphorylation and Control of Dendritic Morphology Are Impaired by Rare Genetic Variants
Cell reports, Jan 8, 2016
The development of neural connectivity is essential for brain function, and disruption of this pr... more The development of neural connectivity is essential for brain function, and disruption of this process is associated with autism spectrum disorders (ASDs). DIX domain containing 1 (DIXDC1) has previously been implicated in neurodevelopmental disorders, but its role in postnatal brain function remains unknown. Using a knockout mouse model, we determined that DIXDC1 is a regulator of excitatory neuron dendrite development and synapse function in the cortex. We discovered that MARK1, previously linked to ASDs, phosphorylates DIXDC1 to regulate dendrite and spine development through modulation of the cytoskeletal network in an isoform-specific manner. Finally, rare missense variants in DIXDC1 were identified in ASD patient cohorts via genetic sequencing. Interestingly, the variants inhibit DIXDC1 isoform 1 phosphorylation, causing impairment to dendrite and spine growth. These data reveal that DIXDC1 is a regulator of cortical dendrite and synaptic development and provide mechanistic in...
Cortical neurons gradually attain a post-mitotic state
Cell Research, 2016
Once generated, neurons are thought to permanently exit the cell cycle and become irreversibly di... more Once generated, neurons are thought to permanently exit the cell cycle and become irreversibly differentiated. However, neither the precise point at which this post-mitotic state is attained nor the extent of its irreversibility is clearly defined. Here we report that newly born neurons from the upper layers of the mouse cortex, despite initiating axon and dendrite elongation, continue to drive gene expression from the neural progenitor tubulin α1 promoter (Tα1p). These observations suggest an ambiguous post-mitotic neuronal state. Whole transcriptome analysis of sorted upper cortical neurons further revealed that neurons continue to express genes related to cell cycle progression long after mitotic exit until at least post-natal day 3 (P3). These genes are however down-regulated thereafter, associated with a concomitant up-regulation of tumor suppressors at P5. Interestingly, newly born neurons located in the cortical plate (CP) at embryonic day 18-19 (E18-E19) and P3 challenged with calcium influx are found in S/G2/M phases of the cell cycle, and still able to undergo division at E18-E19 but not at P3. At P5 however, calcium influx becomes neurotoxic and leads instead to neuronal loss. Our data delineate an unexpected flexibility of cell cycle control in early born neurons, and describe how neurons transit to a post-mitotic state.Cell Research advance online publication 21 June 2016; doi:10.1038/cr.2016.76.
Up to now, the cellular and molecular bases of aging and neural plasticity remain unknown. This p... more Up to now, the cellular and molecular bases of aging and neural plasticity remain unknown. This paper analyzes this problem from a developmental point of view, taking into consideration the coexistence of different cellular microenvironments coexisting in the nervous system (NS), predetermined by specific developmental pathways, which directly influence the nervous function in the organism. The developmental changes in the subunit composition of the NMDA subtype of glutamate receptors is analyzed following this approach, and changes demonstrated in these structures are compared with those observed in receptors from differentiated nervous tissues as a consequence of plastic phenomena. Finally, based on the results of this analysis we postulate an hypothesis relating the developmental changes to the Alzheimer´s disease.
Spermine inhibits [3H]glycine binding at the NMDA receptors from plexiform layers of chick retina
Neurochemical research, 1998
Saturable specific binding of glycine to synaptosomal membranes from plexiform layers of the reti... more Saturable specific binding of glycine to synaptosomal membranes from plexiform layers of the retina has been described, which seems to correspond to the modulatory site on NMDA-receptors (26). Spermine inhibited specific [3H]glycine binding to membranes from synaptosomal fractions from the outer (P1) and the inner (P2) plexiform layers of 1-3 day-old chick retinas in a dose-dependent manner with an IC50 = 35 microM for the P1 fraction and 32 microM for the P2 fraction. Kinetic experiments and non-linear regression analysis of [3H]glycine-specific binding showed a Kd approximately 100-150 nM in both fractions, and a higher Bmax (4.11 +/- 0.47 pmol/mg protein) for the inner plexiform layer compared to the outer plexiform layer (Bmax = 2.76 +/- 0.25 pmol/mg protein). Strychnine-insensitive [3H]glycine binding was inhibited by 100 microM spermine, due to a reduction in Bmax (P1 = 0.84 +/- 0.16 pmol/mg protein; P2 = 0.81 +/- 0.16 pmol/mg protein) without affecting the Kd. Association and...
The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 11, 2015
Perturbations in fast-spiking parvalbumin (PV) interneurons are hypothesized to be a major compon... more Perturbations in fast-spiking parvalbumin (PV) interneurons are hypothesized to be a major component of various neuropsychiatric disorders; however, the mechanisms regulating PV interneurons remain mostly unknown. Recently, cyclin-dependent kinase 5 (Cdk5) has been shown to function as a major regulator of synaptic plasticity. Here, we demonstrate that genetic ablation of Cdk5 in PV interneurons in mouse brain leads to an increase in GABAergic neurotransmission and impaired synaptic plasticity. PVCre;fCdk5 mice display a range of behavioral abnormalities, including decreased anxiety and memory impairment. Our results reveal a central role of Cdk5 expressed in PV interneurons in gating inhibitory neurotransmission and underscore the importance of such regulation during behavioral tasks. Our findings suggest that Cdk5 can be considered a promising therapeutic target in a variety of conditions attributed to inhibitory interneuronal dysfunction, such as epilepsy, anxiety disorders, and ...
Communicative & Integrative Biology, 2011
T he shape of a neuron supplies valuable clues as to its function. Neurons typically extend a sin... more T he shape of a neuron supplies valuable clues as to its function. Neurons typically extend a single long, thin axon, which will transmit signals and several shorter and thicker dendrites, which will receive signals. The understanding of the means by which neurons acquire a polarized morphology is a fundamental issue in developmental neurobiology. The current view suggests that axon selection involves a stochastic mechanism. However, new data suggest that a polarized cytoplasm not only determines the position of neurite emergence, but also sets the conditions for morphological polarization. In vertebrates, neurons migrate before establishing their final morphology. Recent work shows that the polarized cytoplasm also determines how neurons migrate. Thus, neuronal migration might influence the processes by which neurons form an axon.
![Research paper thumbnail of Strychnine-insensitive [3H] glycine binding to synaptosomal membranes from the chick retina](https://attachments.academia-assets.com/54045290/thumbnails/1.jpg)
International Journal of Developmental Neuroscience, 1998
The pharmacology and kinetics of strychnine!insensitive ð 2 HŁ glycine binding to synaptic mem! b... more The pharmacology and kinetics of strychnine!insensitive ð 2 HŁ glycine binding to synaptic mem! branes from the outer "P 0 # and the inner "P 1 # plexiform layers of chick retina was studied[ Inhibition curves for glycine\ D!serine\ 0!amincyclopropanecarboxylic acid "ACPC# and strychnine were analyzed by non! linear regression[ Hill slopes for glycine and D!serine were not di}erent from unity\ whereas those for ACPC were ³ 0 in both fractions\ revealing heterogeneity of binding sites in these membranes[ Non!linear regression analysis of time course and saturation experiments strengthen the idea that ð 2 HŁ glycine binds to more than one class of sites\ with similar a.nities at equilibrium[ Antagonists of strychnine!insensitive glycine receptors in the CNS did not inhibit ð 2 HŁ glycine binding to these membranes\ which demonstrates that NMDA receptors in the retina have di}erent structural requirements for ligand interaction at these sites[ pH a}ected the speci_c binding\ in agreement with the participation of speci_c amino acid residues at glycine binding sites on NMDA receptors\ and also with functional studies in which the modulation of a.nity at this site by protons has been observed[ These results support previous studies regarding CPP and MK!790 binding\ and provide evidence which indicates that the pharmacophore for glycine and other NMDA!related ligands is distinct for the retina\ compared to the CNS\ mainly regarding the e}ects of glycine!site antagonists[ Þ 0887 ISDN[ Published by Elsevier Science Ltd
Journal of Neuroscience, 2010
The mechanisms underlying the normal development of neuronal morphology remain a fundamental ques... more The mechanisms underlying the normal development of neuronal morphology remain a fundamental question in neurobiology. Studies in cultured neurons have suggested that the position of the centrosome and the Golgi may predict the site of axon outgrowth. During neuronal migration in the developing cortex, however, the centrosome and Golgi are oriented toward the cortical plate at a time when axons grow toward the ventricular zone. In the current work, we use in situ live imaging to demonstrate that the centrosome and the accompanying polarized cytoplasm exhibit apical translocation in newborn cortical neurons preceding initial axon outgrowth. Disruption of centrosomal activity or downregulation of the centriolar satellite protein PCM-1 affects axon formation. We further show that downregulation of the centrosomal protein Cep120 impairs microtubule organization, resulting in increased centrosome motility. Decreased centrosome motility resulting from microtubule stabilization causes an aberrant centrosomal localization, leading to misplaced axonal outgrowth. Our results reveal the dynamic nature of the centrosome in developing cortical neurons, and implicate centrosome translocation and microtubule organization during the multipolar stage as important determinants of axon formation.
Neuron, 2010
Centrosome functions are important in multiple brain developmental processes. Proper functioning ... more Centrosome functions are important in multiple brain developmental processes. Proper functioning of the centrosome relies on assembly of protein components into the pericentriolar material. This dynamic assembly is mediated by the trafficking of pericentriolar satellites, which are comprised of centrosomal proteins. Here we demonstrate that trafficking of pericentriolar satellites requires the interaction between Hook3 and Pericentriolar Material 1 (PCM1). Hook3, previously shown to link the centrosome and the nucleus in C. elegans, is recruited to pericentriolar satellites through interaction with PCM1, a protein associated with schizophrenia. Disruption of the Hook3-PCM1 interaction in vivo impairs interkinetic nuclear migration, a featured behavior of embryonic neural progenitors. This in turn leads to overproduction of neurons and premature depletion of the neural progenitor pool in the developing neocortex. These results underscore the importance of centrosomal assembly in neurogenesis and provide potential insights into the etiology of brain developmental diseases related to the centrosome dysfunction.
Nature, 2005
Neuronal polarization occurs shortly after mitosis. In neurons differentiating in vitro, axon for... more Neuronal polarization occurs shortly after mitosis. In neurons differentiating in vitro, axon formation follows the segregation of growth-promoting activities to only one of the multiple neurites that form after mitosis 1,2 . It is unresolved whether such spatial restriction makes use of an intrinsic program, like during C. elegans embryo polarization 3 , or is extrinsic and cue-mediated, as in migratory cells 4 . Here we show that in hippocampal neurons in vitro, the axon consistently arises from the neurite that develops first after mitosis. Centrosomes, the Golgi apparatus and endosomes cluster together close to the area where the first neurite will form, which is in turn opposite from the plane of the last mitotic division. We show that the polarized activities of these organelles are necessary and sufficient for neuronal polarization: (1) polarized microtubule polymerization and membrane transport precedes first neurite formation, (2) neurons with more than one centrosome sprout more than one axon and (3) suppression of centrosome-mediated functions precludes polarization. We conclude that asymmetric centrosome-mediated dynamics in the early post-mitotic stage instruct neuronal polarity, implying that pre-mitotic mechanisms with a role in division orientation may in turn participate in this event.
Molecular Psychiatry, 2014
Pyramidal neuron polarity axis is defined at the bipolar stage
Journal of Cell Science, 2008
In situ observations of the development of hippocampal and cortical neurons indicate that final a... more In situ observations of the development of hippocampal and cortical neurons indicate that final axon-dendrite identity is defined at the time of generation of the first two, oppositely positioned, neurites. Quite differently, in vitro studies demonstrated that axonal fate is defined by the stochastic selection of one of the multiple minor neurites for fast outgrowth. By analyzing the fate of all neurites, starting at the time of emergence from the cell body, we demonstrate that polarity is defined at the bipolar stage, with one of the two first-appearing neurites acquiring axonal fate, irrespective of how many other neurites later form. The first two neurites have, as in vivo, the highest growth potential, as cutting the axon results in the growth of a new axon from the neurite at the opposite pole, and cutting this induces regrowth from the first. This temporal and spatial hierarchical definition of polarized growth, together with the bipolar organization of microtubule dynamics and membrane transport preceding it, is consistent with polarity being initiated by an intrinsic program. In this scenario, molecules required for axon specification would act at one of the first two neurites and extrinsic cues will be required for final commitment of polarity.
![Research paper thumbnail of Calcium-independent release of []spermine from chick retina](https://attachments.academia-assets.com/54045289/thumbnails/1.jpg)
Brain Research, 2000
Spermine has been shown to influence NMDA receptor function through an interaction at the coagoni... more Spermine has been shown to influence NMDA receptor function through an interaction at the coagonist site for glycine in the central Ž . nervous system CNS and the retina. In order to support a role for spermine as neurotransmitter or neuromodulator in the chick retina, w 3 x specific stimulated-release of spermine should be demonstrated. Isolated chick retinas, preloaded with H spermine, were stimulated with w 3 x 1 mM NMDA and other glutamate agonists at ionotropic receptors, in a continuous superfusion system. H spermine was released from the retina by depolarization with 50 mM KCl, in a Ca 2q -independent manner. Inhibition of Na q rK q -ATPase by ouabain or digitoxigenin also induced spermine release following 36 min in the presence of the drugs; such effect seems unrelated to changes in Na q electrochemical gradients, since nigericin and veratrine did not induce release in Na q containing medium. The lack of effect of glutamate, NMDA and kainate at 1 mM concentration, suggests that release of spermine in the retina is mediated by the reversal of uptake and not necessarily linked to EAA-receptor activation. q
Nature Neuroscience, 2012
How neurons develop their morphology is an important question in neurobiology. Here we describe a... more How neurons develop their morphology is an important question in neurobiology. Here we describe a new pathway that specifically affects the formation of basal dendrites and axonal projections in cortical pyramidal neurons. We report that thousand-and-oneamino acid 2 kinase (TAOK2), also known as TAO2, is essential for dendrite morphogenesis. TAOK2 downregulation impairs basal dendrite formation in vivo without affecting apical dendrites. Moreover, TAOK2 interacts with Neuropilin 1 (Nrp1), a receptor protein that binds the secreted guidance cue Semaphorin 3A (Sema3A). TAOK2 overexpression restores dendrite formation in cultured cortical neurons from Nrp1 Sema− mice, which express Nrp1 receptors incapable of binding Sema3A. TAOK2 overexpression also ameliorates the basal dendrite impairment resulting from Nrp1 downregulation in vivo. Finally, Sema3A and TAOK2 modulate the formation of basal dendrites through the activation of the c-Jun N-terminal kinase (JNK). These results delineate a pathway whereby Sema3A and Nrp1 transduce signals through TAOK2 and JNK to regulate basal dendrite development in cortical neurons.
Uploads
Papers by Froylan de Anda