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Experimental Neurology Jun 2024Alleviation of motor impairment by aerobic exercise (AE) in Parkinson's disease (PD) patients points to activation of neurobiological mechanisms that may be targetable...
Moderate intensity aerobic exercise alleviates motor deficits in 6-OHDA lesioned rats and reduces serum levels of biomarkers of Parkinson's disease severity without recovery of striatal dopamine or tyrosine hydroxylase.
Alleviation of motor impairment by aerobic exercise (AE) in Parkinson's disease (PD) patients points to activation of neurobiological mechanisms that may be targetable by therapeutic approaches. However, evidence for AE-related recovery of striatal dopamine (DA) signaling or tyrosine hydroxylase (TH) loss has been inconsistent in rodent studies. This ambiguity may be related to the timing of AE intervention in relation to the status of nigrostriatal neuron loss. Here, we replicated human PD at diagnosis by establishing motor impairment with >80% striatal DA and TH loss prior to initiating AE, and assessed its potential to alleviate motor decline and restore DA and TH loss. We also evaluated if serum levels of neurofilament light (NfL) and glial fibrillary acidic protein (GFAP), biomarkers of human PD severity, changed in response to AE. 6-hydroxydopamine (6-OHDA) was infused unilaterally into rat medial forebrain bundle to induce progressive nigrostriatal neuron loss over 28 days. Moderate intensity AE (3× per week, 40 min/session), began 8-10 days post-lesion following establishment of impaired forelimb use. Striatal tissue DA, TH protein and mRNA, and serum levels of NfL/GFAP were determined 3-wks after AE began. Despite severe striatal DA depletion at AE initiation, forelimb use deficits and hypokinesia onset were alleviated by AE, without recovery of striatal DA or TH protein loss, but reduced NfL and GFAP serum levels. This proof-of-concept study shows AE alleviates motor impairment when initiated with >80% striatal DA loss without obligate recovery of striatal DA or TH protein. Moreover, the AE-related reduction of NfL and GFAP serum levels may serve as objective blood-based biomarkers of AE efficacy.
PubMed: 38944332
DOI: 10.1016/j.expneurol.2024.114875 -
Developmental Biology Jun 2024During neural development, sculpting of early formed circuits by cell death and synaptic pruning is necessary to generate a functional and efficient nervous system. This...
During neural development, sculpting of early formed circuits by cell death and synaptic pruning is necessary to generate a functional and efficient nervous system. This allows for the establishment of rudimentary circuits which necessitate early organism survival to later undergo subsequent refinement. These changes facilitate additional specificity to stimuli which can lead to increased behavioral complexity. In multiple species, Rohon-Beard neurons (RBs) are the earliest mechanosensory neurons specified and are critical in establishing a rudimentary motor response circuit. Sensory input from RBs gradually becomes redundant as dorsal root ganglion (DRG) neurons develop and integrate into motor circuits. Previous studies demonstrate that RBs undergo a dramatic wave of cell death concurrent with development of the DRG. However, contrary to these studies, we show that neurogenin1 (ngn1) RBs do not undergo a widespread wave of programmed cell death during early zebrafish development and instead persist until at least 15 days post fertilization. Starting at 2 dpf, we also observed a dramatic medialization and shrinkage of ngn1 RB somas along with a gradual downregulation of ngn1 in RBs. This alters a fundamental premise of early zebrafish neural development and opens new avenues to explore mechanisms of RB function, persistence, and circuit refinement.
PubMed: 38944329
DOI: 10.1016/j.ydbio.2024.06.020 -
Annals of the New York Academy of... Jun 2024Interdisciplinary investigations of the human mind through the cognitive sciences have identified a key role of the body in representing knowledge. After characterizing...
Interdisciplinary investigations of the human mind through the cognitive sciences have identified a key role of the body in representing knowledge. After characterizing knowledge at grounded, embodied, and situated levels, number knowledge is analyzed from this hierarchical perspective. Lateralized cortical processing of coarse versus fine detail is identified as a grounding substrate for the population stereotype few/left, many/right, which then contributes to number-related sensory and motor biases at the embodied and situated levels. Implications of this perspective for education and rehabilitation are discussed.
PubMed: 38943430
DOI: 10.1111/nyas.15182 -
Journal of Biomedical Science Jun 2024Enterovirus 71 (EV-A71) causes Hand, Foot and Mouth Disease (HFMD) in children and has been associated with neurological complications. The molecular mechanisms involved...
BACKGROUND
Enterovirus 71 (EV-A71) causes Hand, Foot and Mouth Disease (HFMD) in children and has been associated with neurological complications. The molecular mechanisms involved in EV-A71 pathogenesis have remained elusive.
METHODS
A siRNA screen in EV-A71 infected-motor neurons was performed targeting 112 genes involved in intracellular membrane trafficking, followed by validation of the top four hits using deconvoluted siRNA. Downstream approaches including viral entry by-pass, intracellular viral genome quantification by qPCR, Western blot analyses, and Luciferase reporter assays allowed determine the stage of the infection cycle the top candidate, RAB11A was involved in. Proximity ligation assay, co-immunoprecipitation and multiplex confocal imaging were employed to study interactions between viral components and RAB11A. Dominant negative and constitutively active RAB11A constructs were used to determine the importance of the protein's GTPase activity during EV-A71 infection. Mass spectrometry and protein interaction analyses were employed for the identification of RAB11A's host interacting partners during infection.
RESULTS
Small GTPase RAB11A was identified as a novel pro-viral host factor during EV-A71 infection. RAB11A and RAB11B isoforms were interchangeably exploited by strains from major EV-A71 genogroups and by Coxsackievirus A16, another major causative agent of HFMD. We showed that RAB11A was not involved in viral entry, IRES-mediated protein translation, viral genome replication, and virus exit. RAB11A co-localized with replication organelles where it interacted with structural and non-structural viral components. Over-expression of dominant negative (S25N; GDP-bound) and constitutively active (Q70L; GTP-bound) RAB11A mutants had no effect on EV-A71 infection outcome, ruling out RAB11A's involvement in intracellular trafficking of viral or host components. Instead, decreased ratio of intracellular mature viral particles to viral RNA copies and increased VP0:VP2 ratio in siRAB11-treated cells supported a role in provirion maturation hallmarked by VP0 cleavage into VP2 and VP4. Finally, chaperones, not trafficking and transporter proteins, were found to be RAB11A's top interacting partners during EV-A71 infection. Among which, CCT8 subunit from the chaperone complex TRiC/CCT was further validated and shown to interact with viral structural proteins specifically, representing yet another novel pro-viral host factor during EV-A71 infection.
CONCLUSIONS
This study describes a novel, unconventional role for RAB11A during viral infection where it participates in the complex process of virus morphogenesis by recruiting essential chaperone proteins.
Topics: rab GTP-Binding Proteins; Enterovirus A, Human; Humans; Molecular Chaperones; Virus Replication
PubMed: 38943128
DOI: 10.1186/s12929-024-01053-2 -
Neurological Sciences : Official... Jun 2024Variations in the UBQLN2 gene are associated with a group of diseases with X-linked dominant inheritance and clinical phenotypes of amyotrophic lateral sclerosis (ALS)...
Variations in the UBQLN2 gene are associated with a group of diseases with X-linked dominant inheritance and clinical phenotypes of amyotrophic lateral sclerosis (ALS) and/or frontal temporal lobe dementia (FTD). Cases with UBQLN2 variations have been rarely reported worldwide. The reported cases exhibit strong clinical heterogeneity. Here, we report two adult-onset cases with UBQLN2 variations in Han Chinese. Whole exome sequencing revealed the hemizygous P506S (c.1516C > T) and the heterozygous P509S variation (c.1525C > T), both of which were located within the hotspot mutation region. The patient with the P506S variation was a 24-year-old male. The clinical feature was spastic paraplegia without lower motor neuron damage. The patient's mother was an asymptomatic heterozygote carrier with skewed X-chromosome inactivation. The patient with the P509S variation was a 63-year-old female. Clinical features included ALS and parkinsonism. F-fluorodopa PET-CT revealed presynaptic dopaminergic deficits in bilateral posterior putamen. These cases further highlight the clinical heterogeneity of UBQLN2 cases.
PubMed: 38943019
DOI: 10.1007/s10072-024-07674-7 -
Cell Death Discovery Jun 2024RNA-binding proteins are multifunctional molecules impacting on multiple steps of gene regulation. Gemin5 was initially identified as a member of the survival of motor...
RNA-binding proteins are multifunctional molecules impacting on multiple steps of gene regulation. Gemin5 was initially identified as a member of the survival of motor neurons (SMN) complex. The protein is organized in structural and functional domains, including a WD40 repeats domain at the N-terminal region, a tetratricopeptide repeat (TPR) dimerization module at the central region, and a non-canonical RNA-binding site at the C-terminal end. The TPR module allows the recruitment of the endogenous Gemin5 protein in living cells and the assembly of a dimer in vitro. However, the biological relevance of Gemin5 oligomerization is not known. Here we interrogated the Gemin5 interactome focusing on oligomerization-dependent or independent regions. We show that the interactors associated with oligomerization-proficient domains were primarily annotated to ribosome, splicing, translation regulation, SMN complex, and RNA stability. The presence of distinct Gemin5 protein regions in polysomes highlighted differences in translation regulation based on their oligomerization capacity. Furthermore, the association with native ribosomes and negative regulation of translation was strictly dependent on both the WD40 repeats domain and the TPR dimerization moiety, while binding with the majority of the interacting proteins, including SMN, Gemin2, and Gemin4, was determined by the dimerization module. The loss of oligomerization did not perturb the predominant cytoplasmic localization of Gemin5, reinforcing the cytoplasmic functions of this essential protein. Our work highlights a distinctive role of the Gemin5 domains for its functions in the interaction with members of the SMN complex, ribosome association, and RBP interactome.
PubMed: 38942768
DOI: 10.1038/s41420-024-02057-5 -
The Journal of Neuroscience : the... Jun 2024During navigation, the neocortex must actively integrate learned spatial context with current sensory experience to guide behaviours. However, the relative encoding of...
During navigation, the neocortex must actively integrate learned spatial context with current sensory experience to guide behaviours. However, the relative encoding of spatial and sensorimotor information among cortical cells, and whether hippocampal feedback continues to modify these properties in familiar environments, remains poorly understood. Thus, two-photon microscopy of male and female Thy1-GCaMP6s mice was used to longitudinally image neurons spanning superficial retrosplenial cortex and layers II-Va of primary and secondary motor cortices before and after bilateral dorsal hippocampal lesions. During behaviour on a familiar cued treadmill, the locations of two added obstacles were interchanged to decouple place-tuning from cue-tuning among the position correlated cells with fields at those locations. The subpopulations of place- and cue-tuned cells each formed interareal gradients such that higher-level cortical regions exhibited higher fractions of place cells, whereas lower-level regions exhibited higher fractions of cue cells. Position correlated cells in motor cortex also formed translaminar gradients; cells closer to the cortical surface were more likely to exhibit fields and were more sparsely and precisely tuned than deeper cells. After dorsal hippocampal lesions, a neural representation of the learned environment persisted but retrosplenial cortex exhibited significantly increased cue-tuning and, in motor cortices, both position correlated cell recruitment and population activity at the unstable obstacle locations became more homogeneously elevated across laminae. Altogether, these results support that the hippocampus continues to modulate cortical responses in familiar environments, and the relative impact of top-down feedback obeys hierarchical interareal and interlaminar gradients opposite to the flow of bottom-up sensory inputs. During learning, the hippocampus imparts spatial context to memory representations throughout the superficial neocortex. However, the post-learning role of the hippocampus has not been well defined. The results of this study suggest that, during navigation of a familiar environment, the hippocampus continues to link unreliable sensory attributes to a stable contextual framework, effectively updating the learned model of the environment. The results are also consistent with top-down suppression of sensory-evoked activity during behaviour, which varied in strength according to hierarchical proximity to the hippocampus. This effect was abolished by bilateral lesions of the dorsal hippocampus, supporting that the hippocampus plays an ongoing role in propagating context-dependent predictions throughout the cortical hierarchy, a core hypothesis of the predictive coding theoretical framework.
PubMed: 38942472
DOI: 10.1523/JNEUROSCI.1619-23.2024 -
Neurobiology of Disease Jun 2024Human beings are living longer than ever before and aging is accompanied by an increased incidence of motor deficits, including those associated with the...
Human beings are living longer than ever before and aging is accompanied by an increased incidence of motor deficits, including those associated with the neurodegenerative conditions, Parkinson's disease (PD) and Huntington's disease (HD). However, the biological correlates underlying this epidemiological finding, especially the functional basis at the synapse level, have been elusive. This study reveals that motor skill performance examined via rotarod, beam walking and pole tests is impaired in aged mice. This study, via electrophysiology recordings, further identifies an aging-related reduction in the efficacy of inhibitory synaptic transmission onto dorsolateral striatum (DLS) indirect-pathway medium spiny neurons (iMSNs), i.e., a disinhibition effect on DLS iMSNs. In addition, pharmacologically enhancing the activity of DLS iMSNs by infusing an adenosine A receptor (AR) agonist, which presumably mimics the disinhibition effect, impairs motor skill performance in young mice, simulating the behavior in aged naïve mice. Conversely, pharmacologically suppressing the activity of DLS iMSNs by infusing an AR antagonist, in order to offset the disinhibition effect, restores motor skill performance in aged mice, mimicking the behavior in young naïve mice. In conclusion, this study identifies a functional inhibitory synaptic plasticity in DLS iMSNs that likely contributes to the aging-related motor skill deficits, which would potentially serve as a striatal synaptic basis underlying age being a prominent risk factor for neurodegenerative motor deficits.
PubMed: 38942325
DOI: 10.1016/j.nbd.2024.106582 -
Ageing Research Reviews Jun 2024Parkinson's disease (PD), the second most common neurodegenerative disorder, is characterized by loss of dopaminergic neurons in the substantia nigra, as well as the... (Review)
Review
Parkinson's disease (PD), the second most common neurodegenerative disorder, is characterized by loss of dopaminergic neurons in the substantia nigra, as well as the abnormal accumulation of misfolded α-synuclein. Clinically, PD is featured by typical motor symptoms and some non-motor symptoms. Up to now, although considerable progress has been made in understanding the pathogenesis of PD, there is still no effective therapeutic treatment for the disease. Thus, exploring new therapeutic strategies has been a topic that needs to be addressed urgently. Noteworthy, with the proposal of the microbiota-gut-brain axis theory, antimicrobial drugs have received significant attention due to their effects on regulating the intestinal microbiota. Nowadays, there is growing evidence showing that some antimicrobial drugs may be promising drugs for the treatment of PD. Data from pre-clinical and clinical studies have shown that some antimicrobial drugs may play neuroprotective roles in PD by modulating multiple biochemical and molecular pathways, including reducing α-synuclein aggregation, inhibiting neuroinflammation, regulating mitochondrial structure and function, as well as suppressing oxidative stress. In this paper, we summarized the effects of some antimicrobial drugs on PD treatment from recent pre-clinical and clinical studies. Then, we further discussed the potential of a few antimicrobial drugs for treating PD based on molecular docking and molecular dynamics simulation. Importantly, we highlighted the potential of clorobiocin as the therapeutic strategy for PD owing to its ability to inhibit α-synuclein aggregation. These results will help us to better understand the potential of antimicrobial drugs in treating PD and how antimicrobial drugs may alleviate or reverse the pathological symptoms of PD.
PubMed: 38942200
DOI: 10.1016/j.arr.2024.102387 -
Science Advances Jun 2024Functional deficits in basal ganglia (BG) circuits contribute to cognitive and motor dysfunctions in alcohol use disorder. Chronic alcohol exposure alters synaptic...
Functional deficits in basal ganglia (BG) circuits contribute to cognitive and motor dysfunctions in alcohol use disorder. Chronic alcohol exposure alters synaptic function and neuronal excitability in the dorsal striatum, but it remains unclear how it affects BG output that is mediated by the substantia nigra pars reticulata (SNr). Here, we describe a neuronal subpopulation-specific synaptic organization of striatal and subthalamic (STN) inputs to the medial and lateral SNr. Chronic alcohol exposure (CIE) potentiated dorsolateral striatum (DLS) inputs but did not change dorsomedial striatum and STN inputs to the SNr. Chemogenetic inhibition of DLS direct pathway neurons revealed an enhanced role for DLS direct pathway neurons in execution of an instrumental lever-pressing task. Overall, we reveal a subregion-specific organization of striatal and subthalamic inputs onto the medial and lateral SNr and find that potentiated DLS-SNr inputs are accompanied by altered BG control of action execution following CIE.
Topics: Animals; Neuronal Plasticity; Basal Ganglia; Substantia Nigra; Ethanol; Corpus Striatum; Male; Mice; Neurons; Alcoholism; Neural Pathways
PubMed: 38941461
DOI: 10.1126/sciadv.adm6951