Publications by authors named "Roxana Mesias"

Article Synopsis
  • - The study investigates how prefrontal cortex (PFC) projections develop and affect action-outcome associations in the dorsal striatum of postnatal mice, revealing that PFC axons achieve an adult-like pattern and synaptic strength early in development.
  • - By using Hotspot analysis, researchers found that PFC axons form clusters within the first week after birth, stabilizing over time, while excitatory synapse density continues to increase until adulthood.
  • - Mutant mice lacking the protein Cadherin-8 showed improper PFC axon targeting and reduced synaptic activity, leading to difficulties in action-outcome learning, emphasizing the importance of Cdh8 for the correct formation of these neural pathways.
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Article Synopsis
  • Rational decision-making relies on connections between the prefrontal cortex and the dorsomedial striatum, and disruptions in this projection are linked to various mental health disorders.
  • A study using Hotspot Analysis found that the anatomical positioning of these projections develops early and remains largely stable into adulthood, with steady synapse formation throughout late postnatal development.
  • Mice lacking the adhesion protein Cdh8 showed altered axon terminal positioning and difficulties in learning action-outcome associations, suggesting that early developmental mechanisms play a critical role in the function of corticostriatal connections.
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Intellectual disability (ID), which presents itself during childhood, belongs to a group of neurodevelopmental disorders (NDDs) that are clinically widely heterogeneous and highly heritable, often being caused by single gene defects. Indeed, NDDs can be attributed to mutations at over 1000 loci, and all type of mutations, ranging from single nucleotide variations (SNVs) to large, complex copy number variations (CNVs), have been reported in patients with ID and other related NDDs. In this study, we recruited seven different recessive NDD families with comorbidities to perform a detailed clinical characterization and a complete genomic analysis that consisted of a combination of high throughput SNP-based genotyping and whole-genome sequencing (WGS).

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In this study, we described the identification of a large DNAJB2 (HSJ1) deletion in a family with recessive spinal muscular atrophy and Parkinsonism. After performing homozygosity mapping and whole genome sequencing, we identified a 3.8 kb deletion, spanning the entire DnaJ domain of the HSJ1 protein, as the disease-segregating mutation.

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Unlabelled: Mutations in the gene encoding leucine-rich repeat kinase 2 (LRRK2) can cause Parkinson's disease (PD), and the most common disease-associated mutation, G2019S, increases kinase activity. Because LRRK2 expression levels rise during synaptogenesis and are highest in dorsal striatal spiny projection neurons (SPNs), we tested the hypothesis that the LRRK2-G2019S mutation would alter development of excitatory synaptic networks in dorsal striatum. To circumvent experimental confounds associated with LRRK2 overexpression, we used mice expressing LRRK2-G2019S or D2017A (kinase-dead) knockin mutations.

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Genetic evidence suggests cell-type-specific functions for certain nucleoporins, and gene expression profiling has revealed that nucleoporin p62 (NUP62) transcripts are decreased in the prefrontal cortex of major depressives. Chronic stress, which can precipitate depression, induces changes in the architecture and plasticity of apical dendrites that are particularly evident in the CA3 region of the hippocampus. Genetically targeted translating ribosome affinity purification revealed a selective reduction in translated Nup62 transcripts in CA3 of chronically stressed mice, and the Nup62 protein content of nuclei extracted from whole hippocampus was found to be decreased in chronically stressed rats.

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Abnormal cortical circuits underlie some cognitive and psychiatric disorders, yet the molecular signals that generate normal cortical networks remain poorly understood. Semaphorin 7A (Sema7A) is an atypical member of the semaphorin family that is GPI-linked, expressed principally postnatally, and enriched in sensory cortex. Significantly, SEMA7A is deleted in individuals with 15q24 microdeletion syndrome, characterized by developmental delay, autism, and sensory perceptual deficits.

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Neocortical interactions with the dorsal striatum support many motor and executive functions, and such underlying functional networks are particularly vulnerable to a variety of developmental, neurological, and psychiatric brain disorders, including autism spectrum disorders, Parkinson's disease, and Huntington's disease. Relatively little is known about the development of functional corticostriatal interactions, and in particular, virtually nothing is known of the molecular mechanisms that control generation of prefrontal cortex-striatal circuits. Here, we used regional and cellular in situ hybridization techniques coupled with neuronal tract tracing to show that Cadherin-8 (Cdh8), a homophilic adhesion protein encoded by a gene associated with autism spectrum disorders and learning disability susceptibility, is enriched within striatal projection neurons in the medial prefrontal cortex and in striatal medium spiny neurons forming the direct or indirect pathways.

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Mutations in leucine-rich repeat kinase 2 (LRRK2) underlie an autosomal-dominant form of Parkinson's disease (PD) that is clinically indistinguishable from idiopathic PD. The function of LRRK2 is not well understood, but it has become widely accepted that LRRK2 levels or its kinase activity, which is increased by the most commonly observed mutation (G2019S), regulate neurite growth. However, growth has not been measured; it is not known whether mean differences in length correspond to altered rates of growth or retraction, whether axons or dendrites are impacted differentially or whether effects observed are transient or sustained.

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Missense mutations in LRRK2 (leucine-rich repeat kinase 2) are a major cause of PD (Parkinson's disease). Several antibodies against LRRK2 have been developed, but results using these polyclonal antibodies have varied widely leading to conflicting conclusions. To address this challenge, the Michael J.

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Cortical efferents growing in the same environment diverge early in development. The expression of particular transcription factors dictates the trajectories taken, presumably by regulating responsiveness to guidance cues via cellular mechanisms that are not yet known. Here, we show that cortical neurons that are dissociated and grown in culture maintain their cell type-specific identities defined by the expression of transcription factors.

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