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BioRxiv : the Preprint Server For... Feb 2023Developing neurons undergo a progression of morphological and gene expression changes as they transition from neuronal progenitors to mature, multipolar neurons. Here we...
Developing neurons undergo a progression of morphological and gene expression changes as they transition from neuronal progenitors to mature, multipolar neurons. Here we use RNA-seq and H3K4me3 and H3K27me3 ChIP-seq to analyze how chromatin modifications control gene expression in a specific type of CNS neuron, the mouse cerebellar granule cell (GC). We find that in proliferating GC progenitors (GCPs), H3K4me3/H3K27me3 bivalency is common at neuronal genes and undergoes dynamic changes that correlate with gene expression during migration and circuit formation. Expressing a fluorescent sensor for bivalent H3K4me3 and H3K27me3 domains revealed subnuclear bivalent foci in proliferating GCPs. Inhibiting H3K27 methyltransferases EZH1 and EZH2 and in organotypic cerebellar slices dramatically altered the expression of bivalent genes and induced the downregulation of migration-related genes and upregulation of synaptic genes, inhibited glial-guided migration, and accelerated terminal differentiation. Thus, histone bivalency is required to regulate the timing of the progression from progenitor cells to mature neurons.
PubMed: 36778390
DOI: 10.1101/2023.02.02.526881 -
Neuroscience Bulletin Dec 2019Neuronal polarity is involved in multiple developmental stages, including cortical neuron migration, multipolar-to-bipolar transition, axon initiation, apical/basal...
Neuronal polarity is involved in multiple developmental stages, including cortical neuron migration, multipolar-to-bipolar transition, axon initiation, apical/basal dendrite differentiation, and spine formation. All of these processes are associated with the cytoskeleton and are regulated by precise timing and by controlling gene expression. The P-Rex1 (phosphatidylinositol-3,4,5-trisphosphate dependent Rac exchange factor 1) gene for example, is known to be important for cytoskeletal reorganization, cell motility, and migration. Deficiency of P-Rex1 protein leads to abnormal neuronal migration and synaptic plasticity, as well as autism-related behaviors. Nonetheless, the effects of P-Rex1 overexpression on neuronal development and higher brain functions remain unclear. In the present study, we explored the effect of P-Rex1 overexpression on cerebral development and psychosis-related behaviors in mice. In utero electroporation at embryonic day 14.5 was used to assess the influence of P-Rex1 overexpression on cell polarity and migration. Primary neuron culture was used to explore the effects of P-Rex1 overexpression on neuritogenesis and spine morphology. In addition, P-Rex1 overexpression in the medial prefrontal cortex (mPFC) of mice was used to assess psychosis-related behaviors. We found that P-Rex1 overexpression led to aberrant polarity and inhibited the multipolar-to-bipolar transition, leading to abnormal neuronal migration. In addition, P-Rex1 overexpression affected the early development of neurons, manifested as abnormal neurite initiation with cytoskeleton change, reduced the axon length and dendritic complexity, and caused excessive lamellipodia in primary neuronal culture. Moreover, P-Rex1 overexpression decreased the density of spines with increased height, width, and head area in vitro and in vivo. Behavioral tests showed that P-Rex1 overexpression in the mouse mPFC caused anxiety-like behaviors and a sensorimotor gating deficit. The appropriate P-Rex1 level plays a critical role in the developing cerebral cortex and excessive P-Rex1 might be related to psychosis-related behaviors.
Topics: Animals; Axons; Cell Differentiation; Cell Movement; Cell Polarity; Cerebral Cortex; Dendritic Spines; Embryo, Mammalian; Guanine Nucleotide Exchange Factors; Mice; Mice, Inbred ICR; Motor Activity; Neurites; Neurogenesis; Neurons; Psychotic Disorders
PubMed: 31286410
DOI: 10.1007/s12264-019-00408-2 -
Cerebral Cortex (New York, N.Y. : 1991) May 2020Dmrt5 (Dmrta2) and Dmrt3 are key regulators of cortical patterning and progenitor proliferation and differentiation. In this study, we show an altered apical to...
UNLABELLED
Dmrt5 (Dmrta2) and Dmrt3 are key regulators of cortical patterning and progenitor proliferation and differentiation. In this study, we show an altered apical to intermediate progenitor transition, with a delay in SP neurogenesis and premature birth of Ctip2+ cortical neurons in Dmrt5-/- mice. In addition to the cortical progenitors, DMRT5 protein appears present in postmitotic subplate (SP) and marginal zone neurons together with some migrating cortical neurons. We observed the altered split of preplate and the reduced SP and disturbed radial migration of cortical neurons into cortical plate in Dmrt5-/- brains and demonstrated an increase in the proportion of multipolar cells in primary neuronal cultures from Dmrt5-/- embryonic brains. Dmrt5 affects cortical development with specific time sensitivity that we described in two conditional mice with slightly different deletion time. We only observed a transient SP phenotype at E15.5, but not by E18.5 after early (Dmrt5lox/lox;Emx1Cre), but not late (Dmrt5lox/lox;NestinCre) deletion of Dmrt5. SP was less disturbed in Dmrt5lox/lox;Emx1Cre and Dmrt3-/- brains than in Dmrt5-/- and affects dorsomedial cortex more than lateral and caudal cortex. Our study demonstrates a novel function of Dmrt5 in the regulation of early SP formation and radial cortical neuron migration.
SUMMARY STATEMENT
Our study demonstrates a novel function of Dmrt5 in regulating marginal zone and subplate formation and migration of cortical neurons to cortical plate.
Topics: Animals; Cell Movement; Cell Proliferation; Cerebral Cortex; Embryo, Mammalian; Mice; Mice, Knockout; Mitosis; Neocortex; Neurons; Primary Cell Culture; Transcription Factors
PubMed: 31845734
DOI: 10.1093/cercor/bhz310 -
PloS One 2014Here, we found that the PR domain protein Prdm8 serves as a key regulator of the length of the multipolar phase by controlling the timing of morphological transition. We...
Here, we found that the PR domain protein Prdm8 serves as a key regulator of the length of the multipolar phase by controlling the timing of morphological transition. We used a mouse line with expression of Prdm8-mVenus reporter and found that Prdm8 is predominantly expressed in the middle and upper intermediate zone during both the late and terminal multipolar phases. Prdm8 expression was almost coincident with Unc5D expression, a marker for the late multipolar phase, although the expression of Unc5D was found to be gradually down-regulated to the point at which mVenus expression was gradually up-regulated. This expression pattern suggests the possible involvement of Prdm8 in the control of the late and terminal multipolar phases, which controls the timing for morphological transition. To test this hypothesis, we performed gain- and loss-of-function analysis of neocortical development by using in utero electroporation. We found that the knockdown of Prdm8 results in premature change from multipolar to bipolar morphology, whereas the overexpression of Prdm8 maintained the multipolar morphology. Additionally, the postnatal analysis showed that the Prdm8 knockdown stimulated the number of early born neurons, and differentiated neurons located more deeply in the neocortex, however, majority of those cells could not acquire molecular features consistent with laminar location. Furthermore, we found the candidate genes that were predominantly utilized in both the late and terminal multipolar phases, and these candidate genes included those encoding for guidance molecules. In addition, we also found that the expression level of these guidance molecules was inhibited by the introduction of the Prdm8 expression vector. These results indicate that the Prdm8-mediated regulation of morphological changes that normally occur during the late and terminal multipolar phases plays an important role in neocortical development.
Topics: Animals; Bacterial Proteins; Cerebral Cortex; DNA-Binding Proteins; Electroporation; Embryo, Mammalian; Female; Gene Expression Regulation, Developmental; Gene Knockdown Techniques; Genes, Reporter; Histone Methyltransferases; Histone-Lysine N-Methyltransferase; Injections, Intraventricular; Luminescent Proteins; Mice; Mice, Inbred C57BL; Mice, Inbred ICR; Neurogenesis; Plasmids; Pregnancy; Uterus; Red Fluorescent Protein
PubMed: 24489718
DOI: 10.1371/journal.pone.0086356 -
Current Biology : CB Dec 2022Octopuses are remarkable in their ability to use many arms together during behavior (e.g., see Levy et al., Mather, Byrne et al., and Hanlon et al.). Arm responses...
Octopuses are remarkable in their ability to use many arms together during behavior (e.g., see Levy et al., Mather, Byrne et al., and Hanlon et al.). Arm responses and multi-arm coordination can occur without engagement of major brain regions, which indicates the importance of local proprioceptive responses and peripheral connections. Here, we examine the intramuscular nerve cords (INCs), the key proprioceptive anatomy in the arms. INCs are understood to include proprioceptive neurons, multipolar neurons, and motoneurons (reviewed by Graziadei) and are thought to contribute to structuring whole-arm movement. There are four INCs running the full length of each arm (e.g., see Guérin-Ganivet, Martoja and May, and Graziadei); we focused on the pair closest to the suckers, called the oral INCs. In tracking the oral INCs, we found that they extend proximally and continue beyond the arm, through the arm's base. Each oral INC bypasses two adjacent arms and is continuous with the nearer oral INC of the third arm over. As a result, an arm connects through oral INC pathways to arms that are two arms away to the right and left of it. In addition to connecting distant arms, nerve fibers project from the central region of the INCs, suggesting function in local tissues. The other two INCs, paired aboral INCs, also extend proximally beyond the arm's base with trajectories suggestive of the oral INC pattern. These data identify previously unknown regions of the INCs that link distant arms, creating anatomical connections. They suggest potential INC proprioceptive function in extra-arm tissues and contribute to an understanding of embodied organization for octopus behavioral control..
Topics: Animals; Octopodiformes; Movement; Motor Neurons; Brain; Signal Transduction
PubMed: 36446353
DOI: 10.1016/j.cub.2022.11.007 -
Frontiers in Neuroanatomy 2019Sortilin is a member of the vacuolar protein sorting 10 protein (VPS10P) domain receptor family, which carries out signal transduction and protein transport in cells....
Sortilin is a member of the vacuolar protein sorting 10 protein (VPS10P) domain receptor family, which carries out signal transduction and protein transport in cells. Sortilin serves as the third, G-protein uncoupled, receptor of neurotensin that can modulate various brain functions. More recent data indicate an involvement of sortilin in mood disorders, dementia and Alzheimer-type neuropathology. However, data regarding the normal pattern of regional and cellular expression of sortilin in the human brain are not available to date. Using postmortem adult human brains free of neuropathology, the current study determined sortilin immunoreactivity (IR) across the entire brain. Sortilin IR was broadly present in the cerebrum and subcortical structures, localizing to neurons in the somatodendritic compartment, but not to glial cells. In the cerebrum, sortilin IR exhibited differential regional and laminar patterns, with pyramidal, multipolar and polymorphic neurons in cortical layers II-VI, hippocampal formation and amygdaloid complex more distinctly labeled relative to GABAergic interneurons. In the striatum and thalamus, numerous small-to-medium sized neurons showed light IR, with a small group of large sized neurons heavily labeled. In the midbrain and brainstem, sortilin IR was distinct in neurons at the relay centers of descending and ascending neuroanatomical pathways. Dopaminergic neurons in the substantia nigra, cholinergic neurons in the basal nuclei of Meynert and noradrenergic neurons in the locus coeruleus co-expressed strong sortilin IR in double immunofluorescence. In comparison, sortilin IR was weak in the olfactory bulb and cerebellar cortex, with the mitral and Purkinje cells barely visualized. A quantitative analysis was carried out in the lateral, basolateral, and basomedial nuclei of the amygdaloid complex, as well as cortical layers II-VI, which established a positive correlation between the somal size and the intensity of sortilin IR among labeled neurons. Together, the present study demonstrates a predominantly neuronal expression of sortilin in the human brain with substantial regional and cell-type variability. The enriched expression of sortilin in pyramidal, dopaminergic, noradrenergic and cholinergic neurons suggests that this protein may be particularly required for signal transduction, protein trafficking and metabolic homeostasis in populations of relatively large-sized projective neurons.
PubMed: 30914927
DOI: 10.3389/fnana.2019.00031 -
Journal of Anatomy Oct 2021Several studies conducted on chicken have shown that a single stress exposure may impair or improve memory as well as learning processes. However, to date, stress...
Several studies conducted on chicken have shown that a single stress exposure may impair or improve memory as well as learning processes. However, to date, stress effects on neuronal morphology are poorly investigated wherefore it was of interest to evaluate this further in chicks. Thus, the present study aims to investigate the role of single acute stress (AS) of 24 h food and water deprivation in neuronal plasticity in terms of spine density of the corticoid complex (CC) in 15-day-old chick, Gallus domesticus, by using three neurohistological techniques: Cresyl Violet, Golgi Colonnier, and Golgi Cox technique. The dorsolateral surface of the cerebral hemisphere is occupied by CC which can be differentiated into two subfields: an intermediate corticoid (CI) subfield (arranged in layers) and a dorsolateral corticoid (CDL) subfield. Based on different criteria such as soma shape, dendritic branching pattern, and dendritic spine density, two main moderately spinous groups of neuronal cells were observed in the CC, namely, projection neurons (comprising of multipolar and pyramidal neurons) and stellate neurons. In the present study, the stellate neurons have shown a significant decrease as well as an increase in their spine density in both CI and CDL subfields, whereas the multipolar neurons had shown a significant increase in their spine density in the CDL region only. The present study shows that AS induces neuronal plasticity in terms of spine density in both CI and CDL neurons. The morphological changes in the form of decreased dendritic branches due to stress have been observed in the CI region in comparison to CDL region, which could be linked to more effect of stress in this region. The avian CDL corresponds to the entorhinal cortex of mammals on the basis of neuronal morphology and bidirectional connections between adjacent areas. The projection neurons increase their branches and also their spine number to cope with the stress effects, while the stellate neurons show contrasting effect in their spine density. Therefore, this study will establish that slight modifications in natural stimuli or environmental changes faced by the animal may affect their dorsolateral forebrain which shows neuronal plasticity that help in the development of an adaptive capacity of the animal to survive under changing environmental conditions.
Topics: Adrenal Cortex Hormones; Animals; Chickens; Dendrites; Dendritic Spines; Neuronal Plasticity; Neurons; Pyramidal Cells
PubMed: 34159582
DOI: 10.1111/joa.13483 -
Brain Sciences Feb 2023Neurons in the spinal trigeminal nucleus of a camel were morphologically studied by the Golgi impregnation method. The neurons were classified based on the size and...
Neurons in the spinal trigeminal nucleus of a camel were morphologically studied by the Golgi impregnation method. The neurons were classified based on the size and shape of their cell bodies, the density of their dendritic trees, and the morphology and distribution of their appendages. At least 12 morphological types of neurons were found in the camel spinal trigeminal nucleus, including the following: stalked, islets, octopus-like, lobulated, boat-like, pyramidal, multipolar, round, oval, and elongated neurons. These neurons exhibited large numbers of various forms of appendages that arise not only from their dendrites but also from their cell bodies. Moreover, neurons with unique large dilatations especially at their dendritic branching points were also reported. The neurons reported in this study displayed an array of different sizes and shapes and featured various forms of appendages arising from cell bodies and dendrites. Such morphologically distinctive neuronal cell types might indicate an evolutionary adaptation to pain and temperature processing pathways at the level of the spinal trigeminal nucleus in camels, which traditionally live in a very harsh climatic environment and are frequently exposed to painful stimuli.
PubMed: 36831855
DOI: 10.3390/brainsci13020312 -
PloS One 2018Although critical for studies of gut motility and intestinal regeneration, the in vitro culture of intestinal muscularis with peristaltic function remains a significant...
Although critical for studies of gut motility and intestinal regeneration, the in vitro culture of intestinal muscularis with peristaltic function remains a significant challenge. Periodic contractions of intestinal muscularis result from the coordinated activity of smooth muscle cells (SMC), the enteric nervous system (ENS), and interstitial cells of Cajal (ICC). Reproducing this activity requires the preservation of all these cells in one system. Here we report the first serum-free culture methodology that consistently maintains spontaneous and periodic contractions of murine and human intestinal muscularis cells for months. In this system, SMC expressed the mature marker myosin heavy chain, and multipolar/dipolar ICC, uniaxonal/multipolar neurons and glial cells were present. Furthermore, drugs affecting neural signals, ICC or SMC altered the contractions. Combining this method with scaffolds, contracting cell sheets were formed with organized architecture. With the addition of intestinal epithelial cells, this platform enabled up to 11 types of cells from mucosa, muscularis and serosa to coexist and epithelial cells were stretched by the contracting muscularis cells. The method constitutes a powerful tool for mechanistic studies of gut motility disorders and the functional regeneration of the engineered intestine.
Topics: Animals; Bioengineering; Cell Line; Coculture Techniques; Humans; Infant; Mice; Mice, Inbred C57BL; Muscle Contraction; Muscle, Smooth; Neuroglia; Neurons; Time Factors
PubMed: 29718926
DOI: 10.1371/journal.pone.0195315 -
Frontiers in Cellular Neuroscience 2022Electrical activity is considered a key driver for the neurochemical and morphological maturation of neurons and the formation of neuronal networks. Designer receptors...
Electrical activity is considered a key driver for the neurochemical and morphological maturation of neurons and the formation of neuronal networks. Designer receptors exclusively activated by designer drugs (DREADDs) are tools for controlling neuronal activity at the single cell level by triggering specific G protein signaling. Our objective was to investigate if prolonged silencing of differentiating cortical neurons can influence dendritic and axonal maturation. The DREADD hM4Di couples to G signaling and evokes hyperpolarization GIRK channels. HM4Di was biolistically transfected into neurons in organotypic slice cultures of rat visual cortex, and activated by clozapine-N-oxide (CNO) dissolved in HO; controls expressed hM4Di, but were mock-stimulated with HO. Neurons were analyzed after treatment for two postnatal time periods, DIV 5-10 and 10-20. We found that CNO treatment delays the maturation of apical dendrites of L2/3 pyramidal cells. Further, the number of collaterals arising from the main axon was significantly lower, as was the number of bouton terminaux along pyramidal cell and basket cell axons. The dendritic maturation of L5/6 pyramidal cells and of multipolar interneurons (basket cells and bitufted cells) was not altered by CNO treatment. Returning CNO-treated cultures to CNO-free medium for 7 days was sufficient to recover dendritic and axonal complexity. Our findings add to the view that activity is a key driver in particular of postnatal L2/3 pyramidal cell maturation. Our results further suggest that inhibitory G protein signaling may represent a factor balancing the strong driving force of neurotrophic factors, electrical activity and calcium signaling.
PubMed: 35910251
DOI: 10.3389/fncel.2022.941620