-
PLoS Computational Biology Jul 2023We investigate the relationship between primary dendrite selection of Purkinje cells and migration of their presynaptic partner granule cells during early cerebellar...
We investigate the relationship between primary dendrite selection of Purkinje cells and migration of their presynaptic partner granule cells during early cerebellar development. During postnatal development, each Purkinje cell grows more than three dendritic trees, from which a primary tree is selected for development, whereas the others completely retract. Experimental studies suggest that this selection process is coordinated by physical and synaptic interactions with granule cells, which undergo a massive migration at the same time. However, technical limitations hinder continuous experimental observation of multiple cell populations. To explore possible mechanisms underlying this selection process, we constructed a computational model using a new computational framework, NeuroDevSim. The study presents the first computational model that simultaneously simulates Purkinje cell growth and the dynamics of granule cell migrations during the first two postnatal weeks, allowing exploration of the role of physical and synaptic interactions upon dendritic selection. The model suggests that interaction with parallel fibers is important to establish the distinct planar morphology of Purkinje cell dendrites. Specific rules to select which dendritic trees to keep or retract result in larger winner trees with more synaptic contacts than using random selection. A rule based on afferent synaptic activity was less effective than rules based on dendritic size or numbers of synapses.
Topics: Purkinje Cells; Dendrites; Axons; Synapses; Cerebellum
PubMed: 37486917
DOI: 10.1371/journal.pcbi.1011320 -
Nature May 2024The human brain develops through a tightly organized cascade of patterning events, induced by transcription factor expression and changes in chromatin accessibility....
The human brain develops through a tightly organized cascade of patterning events, induced by transcription factor expression and changes in chromatin accessibility. Although gene expression across the developing brain has been described at single-cell resolution, similar atlases of chromatin accessibility have been primarily focused on the forebrain. Here we describe chromatin accessibility and paired gene expression across the entire developing human brain during the first trimester (6-13 weeks after conception). We defined 135 clusters and used multiomic measurements to link candidate cis-regulatory elements to gene expression. The number of accessible regions increased both with age and along neuronal differentiation. Using a convolutional neural network, we identified putative functional transcription factor-binding sites in enhancers characterizing neuronal subtypes. We applied this model to cis-regulatory elements linked to ESRRB to elucidate its activation mechanism in the Purkinje cell lineage. Finally, by linking disease-associated single nucleotide polymorphisms to cis-regulatory elements, we validated putative pathogenic mechanisms in several diseases and identified midbrain-derived GABAergic neurons as being the most vulnerable to major depressive disorder-related mutations. Our findings provide a more detailed view of key gene regulatory mechanisms underlying the emergence of brain cell types during the first trimester and a comprehensive reference for future studies related to human neurodevelopment.
PubMed: 38693260
DOI: 10.1038/s41586-024-07234-1 -
Journal of Neuroscience Research Nov 2023One group of the K ion channels, the small-conductance Ca -activated potassium channels (K 2.x, also known as SK channels family), is widely expressed in neurons as well... (Review)
Review
One group of the K ion channels, the small-conductance Ca -activated potassium channels (K 2.x, also known as SK channels family), is widely expressed in neurons as well as the heart, endothelial cells, etc. They are named small-conductance Ca -activated potassium channels (SK channels) due to their comparatively low single-channel conductance of about ~10 pS. These channels are insensitive to changes in membrane potential and are activated solely by rises in the intracellular Ca . According to the phylogenic research done on the K 2.x channels family, there are three channels' subtypes: K 2.1, K 2.2, and K 2.3, which are encoded by KCNN1, KCNN2, and KCNN3 genes, respectively. The K 2.x channels regulate neuronal excitability and responsiveness to synaptic input patterns. K 2.x channels inhibit excitatory postsynaptic potentials (EPSPs) in neuronal dendrites and contribute to the medium afterhyperpolarization (mAHP) that follows the action potential bursts. Multiple brain regions, including the hippocampus, express the K 2.2 channel encoded by the KCNN2 gene on chromosome 5. Of particular interest, rat cerebellar Purkinje cells express K 2.2 channels, which are crucial for various cellular processes during development and maturation. Patients with a loss-of-function of KCNN2 mutations typically exhibit extrapyramidal symptoms, cerebellar ataxia, motor and language developmental delays, and intellectual disabilities. Studies have revealed that autosomal dominant neurodevelopmental movement disorders resembling rodent symptoms are caused by heterozygous loss-of-function mutations, which are most likely to induce KCNN2 haploinsufficiency. The K 2.2 channel is a promising drug target for spinocerebellar ataxias (SCAs). SCAs exhibit the dysregulation of firing in cerebellar Purkinje cells which is one of the first signs of pathology. Thus, selective K 2.2 modulators are promising potential therapeutics for SCAs.
Topics: Rats; Animals; Potassium Channels; Endothelial Cells; Neurons; Membrane Potentials; Purkinje Cells
PubMed: 37466411
DOI: 10.1002/jnr.25233 -
NeuroImage Aug 2023Magnetic Resonance Imaging (MRI) resolution continues to improve, making it important to understand the cellular basis for different MRI contrast mechanisms....
Magnetic Resonance Imaging (MRI) resolution continues to improve, making it important to understand the cellular basis for different MRI contrast mechanisms. Manganese-enhanced MRI (MEMRI) produces layer-specific contrast throughout the brain enabling in vivo visualization of cellular cytoarchitecture, particularly in the cerebellum. Due to the unique geometry of the cerebellum, especially near the midline, 2D MEMRI images can be acquired from a relatively thick slice by averaging through areas of uniform morphology and cytoarchitecture to produce very high-resolution visualization of sagittal planes. In such images, MEMRI hyperintensity is uniform in thickness throughout the anterior-posterior axis of sagittal sections and is centrally located in the cerebellar cortex. These signal features suggested that the Purkinje cell layer, which houses the cell bodies of the Purkinje cells and the Bergmann glia, is the source of hyperintensity. Despite this circumstantial evidence, the cellular source of MRI contrast has been difficult to define. In this study, we quantified the effects of selective ablation of Purkinje cells or Bergmann glia on cerebellar MEMRI signal to determine whether signal could be assigned to one cell type. We found that the Purkinje cells, not the Bergmann glia, are the primary of source of the enhancement in the Purkinje cell layer. This cell-ablation strategy should be useful for determining the cell specificity of other MRI contrast mechanisms.
Topics: Humans; Manganese; Cerebellum; Purkinje Cells; Neuroglia; Magnetic Resonance Imaging
PubMed: 37245561
DOI: 10.1016/j.neuroimage.2023.120198 -
Science Advances Jan 2024Transcription factors play vital roles in neuron development; however, little is known about the role of these proteins in maintaining neuronal homeostasis. Here, we...
Transcription factors play vital roles in neuron development; however, little is known about the role of these proteins in maintaining neuronal homeostasis. Here, we show that the transcription factor RREB1 (Ras-responsive element-binding protein 1) is essential for neuron survival in the mammalian brain. A spontaneous mouse mutation causing loss of a nervous system-enriched transcript is associated with progressive loss of cerebellar Purkinje cells and ataxia. Analysis of chromatin immunoprecipitation and sequencing, along with RNA sequencing data revealed dysregulation of RREB1 targets associated with the microtubule cytoskeleton. In agreement with the known role of microtubules in dendritic development, dendritic complexity was disrupted in -deficient neurons. Analysis of sequencing data also suggested that RREB1 plays a role in the endomembrane system. Mutant Purkinje cells had fewer numbers of autophagosomes and lysosomes and contained P62- and ubiquitin-positive inclusions. Together, these studies demonstrate that RREB1 functions to maintain the microtubule network and proteostasis in mammalian neurons.
Topics: Animals; Mice; Mammals; Microtubules; Neurons; Proteostasis; Purkinje Cells; Transcription Factors
PubMed: 38198538
DOI: 10.1126/sciadv.adh3929 -
Acta Neurologica Belgica Apr 2024Familial Adult Myoclonus Epilepsy (FAME), with a prevalence of < 1/35 000, is known under different acronyms. The disease is transmitted in an autosomal dominant... (Review)
Review
Familial Adult Myoclonus Epilepsy (FAME), with a prevalence of < 1/35 000, is known under different acronyms. The disease is transmitted in an autosomal dominant manner and is characterized by the occurrence of cortical myoclonic tremor, overt myoclonus, and rare bilateral tonic-clonic seizures. FAME is considered neurodegenerative, although it is relatively slow in progression. Diagnosis is based on specific neurophysiological testing, namely jerk-locked back-averaging, somatosensory evoked potentials, long latency reflex, and motor evoked potentials, among others. Imaging data, including functional magnetic resonance imaging, indicate a cortical origin of the cortical myoclonic tremor and decreased cerebellar activation. Cerebellar changes in Purkinje cells have been noted, from few neuropathology reports, in patients from isolated pedigrees. The differential diagnosis includes essential tremor, some forms of genetic generalized epilepsy, and progressive myoclonus epilepsies. Treatment is mainly symptomatic.
Topics: Adult; Humans; Myoclonus; Tremor; Epilepsies, Myoclonic; Evoked Potentials, Somatosensory; Reflex; Electroencephalography
PubMed: 38114875
DOI: 10.1007/s13760-023-02432-6 -
JACC. Clinical Electrophysiology Dec 2023Multifocal ectopic Purkinje-related premature contractions (MEPPCs) are associated with SCN5A variants. However, it is not well understood why Purkinje fibers, but not...
BACKGROUND
Multifocal ectopic Purkinje-related premature contractions (MEPPCs) are associated with SCN5A variants. However, it is not well understood why Purkinje fibers, but not ventricular myocardium, play a predominant role in arrhythmogenesis.
OBJECTIVES
This study sought to explore the underlying mechanisms of MEPPC.
METHODS
Whole-cell patch-clamp and molecular biology techniques were used in the present study.
RESULTS
Clinical data from one patient with R814W variant showed MEPPC syndrome, which is well responsive to amiodarone. Compared with canine ventricular myocytes, Purkinje cells (PCs) had significantly larger sodium current (I), leftward shift of I activation and inactivation curves, suggesting higher sodium channel excitability in PCs. Real-time polymerase chain reaction and Western blot analysis showed that the mRNA and protein expression of Naβ1 and Naβ3 was higher in canine Purkinje fibers than in ventricular myocardium. I in heterologous Chinese hamster ovary cell expression system co-expressing Na1.5 and Naβ1/Naβ3 exhibited similar biophysical properties of I in PCs. R814W variant shifted I activation in a hyperdepolarized direction, caused a larger window current, and generated an outward-gating pore current at depolarized voltages. Coexpression of Naβ1/Naβ3 with Nav1.5-R814W further left-shifted I activation and caused an even larger window current and gating pore current, suggesting higher susceptibility of Purkinje fibers to R814W variant. Amiodarone inhibited I, shifted its inactivation to more negative voltages, and significantly decreased the window current.
CONCLUSIONS
A higher expression of β1 and β3 subunits contributes to higher sodium channel excitability in cardiac Purkinje fibers, making them more susceptible to MEPPC.
Topics: Cricetinae; Humans; Animals; Dogs; Purkinje Fibers; CHO Cells; Cricetulus; Arrhythmias, Cardiac; Amiodarone
PubMed: 37831033
DOI: 10.1016/j.jacep.2023.08.029 -
Cell Stem Cell Jan 2024The developing human cerebellum has a greater diversity of progenitor types than that of the mouse, necessitating a human-based model for studying cerebellar development...
The developing human cerebellum has a greater diversity of progenitor types than that of the mouse, necessitating a human-based model for studying cerebellar development and disease. Atamian et al. developed a 3D organoid model of cerebellar development, which recapitulates many cell types found in the developing human cerebellum, including Purkinje-neuron-like cells.
Topics: Humans; Animals; Mice; Organoids; Cerebellum
PubMed: 38181748
DOI: 10.1016/j.stem.2023.12.007 -
Phytomedicine : International Journal... Apr 2024Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder in which social impairment is the core symptom. Presently, there are no definitive medications to cure...
BACKGROUND
Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder in which social impairment is the core symptom. Presently, there are no definitive medications to cure core symptoms of ASD, and most therapeutic strategies ameliorate ASD symptoms. Treatments with proven efficacy in autism are imminent. Ligustilide (LIG), an herbal monomer extracted from Angelica Sinensis and Chuanxiong, is mainly distributed in the cerebellum and widely used in treating neurological disorders. However, there are no studies on its effect on autistic-like phenotypes and its mechanism of action.
PURPOSE
Investigate the efficacy and mechanism of LIG in treating ASD using two Valproic acid(VPA)-exposed and BTBR T + Itpr3tf/J (BTBR) mouse models of autism.
METHODS
VPA-exposed mice and BTBR mice were given LIG for treatment, and its effect on autistic-like phenotype was detected by behavioral experiments, which included a three-chamber social test. Subsequently, RNA-Sequence(RNA-Seq) of the cerebellum was performed to observe the biological changes to search target pathways. The autophagy and ferroptosis pathways screened were verified by WB(Western Blot) assay, and the cerebellum was stained by immunofluorescence and examined by electron microscopy. To further explore the therapeutic mechanism, ULK1 agonist BL-918 was used to block the therapeutic effect of LIG to verify its target effect.
RESULTS
Our work demonstrates that LIG administration from P12-P14 improved autism-related behaviors and motor dysfunction in VPA-exposed mice. Similarly, BTBR mice showed the same improvement. RNA-Seq data identified ULK1 as the target of LIG in regulating ferritinophagy in the cerebellum of VPA-exposed mice, as evidenced by activated autophagy, increased ferritin degradation, iron overload, and lipid peroxidation. We found that VPA exposure-induced ferritinophagy occurred in the Purkinje cells, with enhanced NCOA4 and Lc3B expressions. Notably, the therapeutic effect of LIG disappeared when ULK1 was activated.
CONCLUSION
LIG treatment inhibits ferritinophagy in Purkinje cells via the ULK1/NCOA4-dependent pathway. Our study reveals for the first time that LIG treatment ameliorates autism symptoms in VPA-exposed mice by reducing aberrant Purkinje ferritinophagy. At the same time, our study complements the pathogenic mechanisms of autism and introduces new possibilities for its therapeutic options.
Topics: Mice; Animals; Valproic Acid; Autistic Disorder; Autism Spectrum Disorder; Purkinje Cells; Mice, Inbred Strains; Disease Models, Animal; Phenylacetates; 4-Butyrolactone
PubMed: 38394737
DOI: 10.1016/j.phymed.2024.155443