Biology subjects

Miramontes, R.

Publications and source records attributed to Miramontes, R..

4 recordsLinked to original sources

bioRxiv2022

Integrated transcriptome analysis of Huntingtons disease iPSC-derived and mouse astrocytes implicates dysregulated synaptogenesis, actin, and astrocyte maturation

Huntingtons disease (HD) is a neurodegenerative disease caused by an expanded CAG repeat within the Huntingtin (HTT) gene having dysregulated cellular homeostasis in the central nervous system, particularly in the striatum and cortex. Astrocytes establish and maintain neuronal functions through the secretion of soluble factors and physical interactions with other neurovascular unit cell types. Under pathological conditions, astrocytes can become reactive, causing cell state transitions that affect brain function. To investigate transitions between cellular states in unaffected and HD astrocytes at high resolution, single-nuclei RNA-sequencing (snRNA-seq) was performed on human HD patient induced pluripotent stem cell (iPSC)-derived astrocytes and on striatal and cortical tissue from a rapidly progressing HD mouse model (R6/2). Analysis of HD human and mouse astrocytes revealed both models have alterations in morphology, glutamate uptake, and dysregulation of astrocyte identity and maturation, whereas dysregulated actin-mediated signaling was unique to human iPSC-derived astrocytes. Representative proteins showed altered levels by Western. In both species, HD transcriptional changes reveal potential astrocyte maturation deficits that were potentially driven by astrogliogenesis transcription factors, including ATF3 and NFIA. When perturbed in a drosophila model of HD, knockdown of NFIA in glia rescued the climbing deficit. These data further support the hypothesis that mutant HTT induces dysregulated astrocyte cell states resulting in dysfunctional astrocytic properties, suggests that some of these states are cell autonomous and maybe unique to human HD, and implicate ATF3 and maturation deficits in HD pathogenesis.

neuroscience↗

bioRxiv2022

Single nuclei RNAseq analysis of HD mouse models and human brain reveals impaired oligodendrocyte maturation and potential role for thiamine metabolism

The complexity of affected brain regions and cell types is a challenge for Huntingtons disease (HD) treatment. Here we used single nucleus RNA sequencing (snRNAseq) to investigate mechanism of pathology in the cortex and striatum from R6/2 mice at 8 and 12w and in three regions of human HD post-mortem tissue. We identified cell type-specific and cell agnostic signatures and found changes suggesting oligodendrocytes (OLs) and oligodendrocyte precursors (OPCs) were arrested in intermediate maturation states. OL-lineage regulators OLIG1 and OLIG2 were negatively correlated with CAG length in human OPCs, and ATACseq analysis of HD mouse NeuN-negative cells showed decreased accessibility of sites regulated by OL maturation genes. Glucose and lipid metabolism were implicated in abnormal cell maturation and PRKCE and Thiamine Pyrophosphokinase 1 were identified as central genes. High dose thiamine/biotin treatment of R6/1 HD mice to target thiamine metabolism not only restored OL maturation, but also rescued pathology in neurons. These findings reveal insights into HD OL pathology that spans multiple brain regions and link OL maturation deficits to abnormal thiamine metabolism.

neuroscience↗

bioRxiv2022

CryoET Reveals Organelle Phenotypes in Huntington Disease Patient iPSC-Derived and Mouse Primary Neurons

Huntingtons Disease (HD) is caused by an expanded CAG repeat in the huntingtin gene, yielding a Huntingtin protein with an expanded polyglutamine tract. Patient-derived induced pluripotent stem cells (iPSCs) can help understand disease; however, defining pathological biomarkers is challenging. Here, we used cryogenic electron tomography to visualize neurites in HD patient iPSC-derived neurons with varying CAG repeats, and primary cortical neurons from BACHD, deltaN17-BACHD, and wild-type mice. In HD models, we discovered mitochondria with enlarged granules and distorted cristae, and thin sheet aggregates in double membrane-bound organelles. We used artificial intelligence to quantify mitochondrial granules, and proteomics to show differential protein content in HD mitochondria. Knockdown of Protein Inhibitor of Activated STAT1 ameliorated aberrant phenotypes in iPSC-neurons and reduced phenotypes in BACHD neurons. We show that integrated ultrastructural and proteomic approaches may uncover early HD phenotypes to accelerate diagnostics and the development of targeted therapeutics for HD.

neuroscience↗

bioRxiv2021

Microglia do not restrict SARS-CoV-2 replication following infection of the central nervous system of K18-hACE2 transgenic mice

Unlike SARS-CoV-1 and MERS-CoV, infection with SARS-CoV-2, the viral pathogen responsible for COVID-19, is often associated with neurologic symptoms that range from mild to severe, yet increasing evidence argues the virus does not exhibit extensive neuroinvasive properties. We demonstrate SARS-CoV-2 can infect and replicate in human iPSC-derived neurons and that infection shows limited anti-viral and inflammatory responses but increased activation of EIF2 signaling following infection as determined by RNA sequencing. Intranasal infection of K18 human ACE2 transgenic mice (K18-hACE2) with SARS-CoV-2 resulted in lung pathology associated with viral replication and immune cell infiltration. In addition, [~]50% of infected mice exhibited CNS infection characterized by wide-spread viral replication in neurons accompanied by increased expression of chemokine (Cxcl9, Cxcl10, Ccl2, Ccl5 and Ccl19) and cytokine (Ifn-{lambda} and Tnf-) transcripts associated with microgliosis and a neuroinflammatory response consisting primarily of monocytes/macrophages. Microglia depletion via administration of colony-stimulating factor 1 receptor inhibitor, PLX5622, in SARS-CoV-2 infected mice did not affect survival or viral replication but did result in dampened expression of proinflammatory cytokine/chemokine transcripts and a reduction in monocyte/macrophage infiltration. These results argue that microglia are dispensable in terms of controlling SARS-CoV-2 replication in in the K18-hACE2 model but do contribute to an inflammatory response through expression of pro-inflammatory genes. Collectively, these findings contribute to previous work demonstrating the ability of SARS-CoV-2 to infect neurons as well as emphasizing the potential use of the K18-hACE2 model to study immunological and neuropathological aspects related to SARS-CoV-2-induced neurologic disease. ImportanceUnderstanding the immunological mechanisms contributing to both host defense and disease following viral infection of the CNS is of critical importance given the increasing number of viruses that are capable of infecting and replicating within the nervous system. With this in mind, the present study was undertaken to evaluate the role of microglia in aiding in host defense following experimental infection of the central nervous system (CNS) of K18-hACE2 with SARS-CoV-2, the causative agent of COVID-19. Neurologic symptoms that range in severity are common in COVID-19 patients and understanding immune responses that contribute to restricting neurologic disease can provide important insight into better understanding consequences associated with SARS-CoV-2 infection of the CNS.

microbiology↗