scholarly journals SMO-M2 mutation does not support cell-autonomous Hedgehog activity in cerebellar granule cell precursors

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Marialaura Petroni ◽  
Maria Sahùn Roncero ◽  
Valentina Ramponi ◽  
Francesca Fabretti ◽  
Vittoria Nicolis Di Robilant ◽  
...  
Keyword(s):  
Granule Cell ◽  
Hedgehog Signaling ◽  
Granule Cells ◽  
Culture Method ◽  
Hedgehog Pathway ◽  
Cellular Models ◽  
Autonomous Activity ◽  
Neoplastic Disorders ◽  
Granule Cell Precursors

AbstractGrowth and patterning of the cerebellum is compromised if granule cell precursors do not properly expand and migrate. During embryonic and postnatal cerebellar development, the Hedgehog pathway tightly regulates granule cell progenitors to coordinate appropriate foliation and lobule formation. Indeed, granule cells impairment or defects in the Hedgehog signaling are associated with developmental, neurodegenerative and neoplastic disorders. So far, scant and inefficient cellular models have been available to study granule cell progenitors, in vitro. Here, we validated a new culture method to grow postnatal granule cell progenitors as hedgehog-dependent neurospheres with prolonged self-renewal and ability to differentiate into granule cells, under appropriate conditions. Taking advantage of this cellular model, we provide evidence that Ptch1-KO, but not the SMO-M2 mutation, supports constitutive and cell-autonomous activity of the hedgehog pathway.

scholarly journals Deletion of Jdp2 enhances Slc7a11 expression in Atoh-1 positive cerebellum granule cell progenitors in vivo

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chia-Chen Ku ◽  
Kenly Wuputra ◽  
Kohsuke Kato ◽  
Jia-Bin Pan ◽  
Chia-Pei Li ◽  
...  
Keyword(s):  
Granule Cell ◽  
Granule Cells ◽  
Apoptotic Cell ◽  
Redox Homeostasis ◽  
Critical Role ◽  
Glutamate Transporter ◽  
Developmental Abnormalities ◽  
Oxidative Stresses

Abstract Background The cerebellum is the sensitive region of the brain to developmental abnormalities related to the effects of oxidative stresses. Abnormal cerebellar lobe formation, found in Jun dimerization protein 2 (Jdp2)-knockout (KO) mice, is related to increased antioxidant formation and a reduction in apoptotic cell death in granule cell progenitors (GCPs). Here, we aim that Jdp2 plays a critical role of cerebellar development which is affected by the ROS regulation and redox control. Objective Jdp2-promoter-Cre transgenic mouse displayed a positive signal in the cerebellum, especially within granule cells. Jdp2-KO mice exhibited impaired development of the cerebellum compared with wild-type (WT) mice. The antioxidation controlled gene, such as cystine-glutamate transporter Slc7a11, might be critical to regulate the redox homeostasis and the development of the cerebellum. Methods We generated the Jdp2-promoter-Cre mice and Jdp2-KO mice to examine the levels of Slc7a11, ROS levels and the expressions of antioxidation related genes were examined in the mouse cerebellum using the immunohistochemistry. Results The cerebellum of Jdp2-KO mice displayed expression of the cystine-glutamate transporter Slc7a11, within the internal granule layer at postnatal day 6; in contrast, the WT cerebellum mainly displayed Sla7a11 expression in the external granule layer. Moreover, development of the cerebellar lobes in Jdp2-KO mice was altered compared with WT mice. Expression of Slc7a11, Nrf2, and p21Cip1 was higher in the cerebellum of Jdp2-KO mice than in WT mice. Conclusion Jdp2 is a critical regulator of Slc7a11 transporter during the antioxidation response, which might control the growth, apoptosis, and differentiation of GCPs in the cerebellar lobes. These observations are consistent with our previous study in vitro.

The chemokine SDF1 regulates migration of dentate granule cells

Development ◽  
2002 ◽  
Vol 129 (18) ◽  
pp. 4249-4260 ◽  
Author(s):  
Anil Bagri ◽  
Theresa Gurney ◽  
Xiaoping He ◽  
Yong-Rui Zou ◽  
Dan R. Littman ◽  
...  
Keyword(s):  
Cell Migration ◽  
Dentate Gyrus ◽  
Granule Cell ◽  
Granule Cells ◽  
Ectopic Expression ◽  
Dentate Granule Cell ◽  
Vitro Assay ◽  
Dentate Granule Cells ◽  
Cell Position

The dentate gyrus is the primary afferent pathway into the hippocampus, but there is little information concerning the molecular influences that govern its formation. In particular, the control of migration and cell positioning of dentate granule cells is not clear. We have characterized more fully the timing and route of granule cell migration during embryogenesis using in utero retroviral injections. Using this information, we developed an in vitro assay that faithfully recapitulates important events in dentate gyrus morphogenesis. In searching for candidate ligands that may regulate dentate granule cell migration, we found that SDF1, a chemokine that regulates cerebellar and leukocyte migration, and its receptor CXCR4 are expressed in patterns that suggest a role in dentate granule cell migration. Furthermore, CXCR4 mutant mice have a defect in granule cell position. Ectopic expression of SDF1 in our explant assay showed that it directly regulates dentate granule cell migration. Our study shows that a chemokine is necessary for the normal development of the dentate gyrus, a forebrain structure crucial for learning and memory.

In Vivo Intracellular Analysis of Granule Cell Axon Reorganization in Epileptic Rats

1999 ◽  
Vol 81 (2) ◽  
pp. 712-721 ◽  
Author(s):  
Paul S. Buckmaster ◽  
F. Edward Dudek
Keyword(s):  
Granule Cell ◽  
Granule Cells ◽  
Molecular Layer ◽  
Axon Collateral ◽  
Cell Axon ◽  
Recurrent Excitation ◽  
The Difference ◽  
Intracellular Analysis

In vivo intracellular analysis of granule cell axon reorganization in epileptic rats. In vivo intracellular recording and labeling in kainate-induced epileptic rats was used to address questions about granule cell axon reorganization in temporal lobe epilepsy. Individually labeled granule cells were reconstructed three dimensionally and in their entirety. Compared with controls, granule cells in epileptic rats had longer average axon length per cell; the difference was significant in all strata of the dentate gyrus including the hilus. In epileptic rats, at least one-third of the granule cells extended an aberrant axon collateral into the molecular layer. Axon projections into the molecular layer had an average summed length of 1 mm per cell and spanned 600 μm of the septotemporal axis of the hippocampus—a distance within the normal span of granule cell axon collaterals. These findings in vivo confirm results from previous in vitro studies. Surprisingly, 12% of the granule cells in epileptic rats, and none in controls, extended a basal dendrite into the hilus, providing another route for recurrent excitation. Consistent with recurrent excitation, many granule cells (56%) in epileptic rats displayed a long-latency depolarization superimposed on a normal inhibitory postsynaptic potential. These findings demonstrate changes, occurring at the single-cell level after an epileptogenic hippocampal injury, that could result in novel, local, recurrent circuits.

Presynaptic Muscarinic Receptors Enhance Glutamate Release at the Mitral/Tufted to Granule Cell Dendrodendritic Synapse in the Rat Main Olfactory Bulb

2009 ◽  
Vol 101 (4) ◽  
pp. 2052-2061 ◽  
Author(s):  
Ambarish S. Ghatpande ◽  
Alan Gelperin
Keyword(s):  
Olfactory Bulb ◽  
Granule Cell ◽  
Basal Forebrain ◽  
Granule Cells ◽  
Calcium Influx ◽  
Glutamate Release ◽  
Gaba Release ◽  
Cellular Mechanisms ◽  
Tufted Cells

The mammalian olfactory bulb receives multiple modulatory inputs, including a cholinergic input from the basal forebrain. Understanding the functional roles played by the cholinergic input requires an understanding of the cellular mechanisms it modulates. In an in vitro olfactory bulb slice preparation we demonstrate cholinergic muscarinic modulation of glutamate release onto granule cells that results in γ-aminobutyric acid (GABA) release onto mitral/tufted cells. We demonstrate that the broad-spectrum cholinergic agonist carbachol triggers glutamate release from mitral/tufted cells that activates both AMPA and NMDA receptors on granule cells. Activation of the granule cell glutamate receptors leads to calcium influx through voltage-gated calcium channels, resulting in spike-independent, asynchronous GABA release at reciprocal dendrodendritic synapses that granule cells form with mitral/tufted cells. This cholinergic modulation of glutamate release persists through much of postnatal bulbar development, suggesting a functional role for cholinergic inputs from the basal forebrain in bulbar processing of olfactory inputs and possibly in postnatal development of the olfactory bulb.

scholarly journals Cerebellar granule cell precursors can extend processes, undergo short migratory movements and express postmitotic markers before mitosis in the chick EGL

2017 ◽  
Author(s):  
Michalina Hanzel ◽  
Richard JT Wingate
Keyword(s):  
Granule Cell ◽  
Granule Cells ◽  
Cerebellar Granule Cells ◽  
Cerebellar Granule Cell ◽  
In Ovo ◽  
Differentiation Markers ◽  
Fixed Tissue ◽  
Cerebellar Granule ◽  
Sequence Of Events ◽  
Granule Cell Precursors

Cerebellar granule cell precursors (GCPs) form a secondary germinative epithelium, the external germinal layer (EGL) where they proliferate extensively to produce the most numerous cell type in the brain. The morphological sequence of events that characterizes the differentiation of GCPs in the EGL is well established. However, morphologies of individual GCP and their differentiation status have never been correlated. Here, we examine the morphological features and transitions of GCPs in the chicken cerebellum by labelling a subset of GCPs with a stable genomic expression of a GFP transgene and following their development within the EGL in fixed tissue and using time-lapse imaging. We use immunohistochemistry to observe cellular morphologies of mitotic and differentiating GCPs to better understand their differentiation dynamics. Results reveal that mitotic activities of GCPs are more complex and dynamic than currently appreciated. While most GCPs divide in the outer and middle EGL, some are capable of division in the inner EGL. Some GCPs remain mitotically active during process extension and tangential migration and retract their processes prior to each cell division. The mitotically active precursors can also express differentiation markers such as TAG1 and NeuroD1. Further, we explore the result of misexpression of NeuroD1 on granule cell development. When misexpressed in GCPs, NeuroD1 leads to premature differentiation, defects in migration and reduced cerebellar size and foliation. Overall, we provide the first characterisation of individual morphologies of mitotically active cerebellar GCPs in ovo and reaffirm the role of NeuroD1 as a differentiation factor in the development of cerebellar granule cells.

scholarly journals The presynaptic glycine transporter GlyT2 is regulated by the Hedgehog pathway in vitro and in vivo

2020 ◽  
Author(s):  
A. de la Rocha-Muñoz ◽  
E. Núñez ◽  
S. Gómez-López ◽  
B. López-Corcuera ◽  
J. de Juan-Sanz ◽  
...  
Keyword(s):  
Hedgehog Signaling ◽  
Hedgehog Pathway ◽  
Mrna Levels ◽  
Loss Of Function ◽  
Transport Activity ◽  
Spinal Cord Neurons ◽  
Glycine Transporter ◽  
Glycinergic Neurotransmission

ABSTRACTThe identity of a glycinergic synapse is maintained presynaptically by the activity of a surface glycine transporter, GlyT2, which recaptures glycine back to presynaptic terminals to preserve vesicular glycine content. GlyT2 loss-of-function mutations cause Hyperekplexia, a rare neurological disease in which loss of glycinergic neurotransmission causes generalized stiffness and strong motor alterations. However, the molecular underpinnings controlling GlyT2 activity remain poorly understood. In this work, we identify the Hedgehog pathway as a robust controller of GlyT2 expression and transport activity. Modulating the activation state of the Hedgehog pathway in vitro in rodent primary spinal cord neurons or in vivo in zebrafish embryos induced a selective control in GlyT2 expression, regulating GlyT2 transport activity. Our results indicate that activation of Hedgehog reduces GlyT2 expression by decreasing its mRNA levels and increasing its ubiquitination and degradation. This work describes a new molecular link between the Hedgehog signaling pathway and presynaptic glycine availability.

scholarly journals Mitotic granule cell precursors undergo highly dynamic morphological transitions throughout the external germinal layer of the chick cerebellum

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Michalina Hanzel ◽  
Victoria Rook ◽  
Richard J. T. Wingate
Keyword(s):  
Granule Cell ◽  
Granule Cells ◽  
Fluorescent Proteins ◽  
Granule Cell Layer ◽  
Germinal Layer ◽  
Proliferation Zone ◽  
Phosphohistone H3 ◽  
Complex Forms ◽  
Differentiation Status ◽  
Granule Cell Precursors

Abstract The developing cerebellum of amniotes is characterised by a unique, transient, secondary proliferation zone: the external germinal layer (EGL). The EGL is comprised solely of granule cell precursors, whose progeny migrate inwardly to form the internal granule cell layer. While a range of cell morphologies in the EGL has long been known, how they reflect the cells’ differentiation status has previously only been inferred. Observations have suggested a deterministic maturation from outer to inner EGL that we wished to test experimentally. To do this, we electroporated granule cell precursors in chick with plasmids encoding fluorescent proteins and probed labelled cells with markers of both proliferation (phosphohistone H3) and differentiation (Axonin1/TAG1 and NeuroD1). We show that granule cell precursors can display a range of complex forms throughout the EGL while mitotically active. Overexpression of full length NeuroD1 within granule cell precursors does not abolish proliferation, but biases granule cells towards precocious differentiation, alters their migration path and results in a smaller and less foliated cerebellum. Our results show that granule cells show a greater flexibility in differentiation than previously assumed. We speculate that this allows the EGL to regulate its proliferative activity in response to overall patterns of cerebellar growth.

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