Biology subjects

Ebert, A. D.

Publications and source records attributed to Ebert, A. D..

3 recordsLinked to original sources

bioRxiv2021

Nitric Oxide Attenuates Human Cytomegalovirus Infection yet Disrupts Neural Cell Differentiation and Tissue Organization

Human cytomegalovirus (HCMV) is a prevalent betaherpesvirus that is asymptomatic in healthy individuals but can cause serious disease in immunocompromised patients. HCMV is also the leading cause of viral-mediated birth defects. Many of these defects manifest within the central nervous system and include microcephaly, sensorineural hearing loss, and cognitive developmental delays. Nitric oxide is a critical effector molecule produced as a component of the innate immune response during infection. Using a 3-dimensional cortical organoid model, we demonstrate that nitric oxide inhibits HCMV spread and simultaneously disrupts neural rosette structures resulting in tissue disorganization. Nitric oxide also attenuates HCMV replication in 2-dimensional cultures of neural progenitor cells (NPCs), a prominent cell type in cortical organoids that differentiate into neurons and glial cells. The multipotency factor SOX2 was decreased during nitric oxide exposure, suggesting early neural differentiation is affected. Maximal mitochondrial respiration was also reduced in both uninfected and infected NPCs. We determined this reduction likely influences neural differentiation as neurons (Tuj1+GFAP-Nestin-) and glial populations (Tuj1-GFAP+Nestin-) were reduced following differentiation. We also observed changes in calcium signaling during exposure to nitric oxide with increased cellular response to ATP (purinergic receptors) and KCl (voltage gated calcium channels). Importantly, nitric oxide could not rescue HCMV-mediated defects in calcium response. Our studies indicate a prominent, immunopathogenic role of nitric oxide in promoting developmental defects within the brain despite its antiviral activity during congenital HCMV infection. Author summaryHuman cytomegalovirus (HCMV) infection can result in serious disease to immunocompromised individuals. HCMV is also the leading cause of viral-mediated congenital birth defects. Congenitally-infected infants can have a variety of symptoms, including microcephaly, sensorineural hearing loss, and developmental delays. The use of 3-dimensional (3-D) cortical organoids to model infection of the fetal brain has advanced the current understanding of developmental defects and allowed a broader investigation of the mechanisms behind disease. Here, we investigate the effect of nitric oxide, a critical effector molecule, on cortical development and HCMV infection. We demonstrate that nitric oxide plays an antiviral role during infection yet results in significant disorganization to cortical tissue. Despite inhibiting viral replication in neural progenitor cells, nitric oxide contributes to differentiation defects of these cells and does not rescue functional consequences of HCMV infection on calcium signaling. Our results indicate that immunopathogenic consequences of nitric oxide during congenital infection promote developmental defects that undermine its antiviral activity.

microbiology↗

bioRxiv2021

Viral mediated knockdown of GATA6 in SMA iPSC-derived astrocytes prevents motor neuron loss and microglial activation

Spinal muscular atrophy (SMA), a pediatric genetic disorder, is characterized by the profound loss of spinal cord motor neurons and subsequent muscle atrophy and death. Although the mechanisms underlying motor neuron loss are not entirely clear, data from our work and others support the idea that glial cells contribute to disease pathology. GATA6, a transcription factor that we have previously shown to be upregulated in SMA astrocytes, is negatively regulated by SMN and can increase the expression of inflammatory regulator NF{kappa}B. In this study, we identified upregulated GATA6 as a contributor to increased activation, pro-inflammatory ligand production, and neurotoxicity in spinal-cord patterned astrocytes differentiated from SMA patient induced pluripotent stem cells. Reducing GATA6 expression in SMA astrocytes via lentiviral infection ameliorated these effects to healthy control levels. Additionally, we found that SMA astrocytes contribute to SMA microglial phagocytosis, which was again decreased by lentiviral-mediated knockdown of GATA6. Together these data identify a role of GATA6 in SMA astrocyte pathology and further highlight glia as important targets of therapeutic intervention in SMA.

neuroscience↗

bioRxiv2021

Downregulation of Neurodevelopmental Gene Expression in iPSC-Derived Cerebral Organoids Upon Infection by Human Cytomegalovirus

Human cytomegalovirus (HCMV) is a beta herpesvirus that, upon congenital infection, can cause severe birth defects including vision and hearing loss, microcephaly, and seizures. Currently, no approved treatment options exist for in utero infections. We previously demonstrated that HCMV infection decreases calcium signaling responses and alters neuronal differentiation in induced pluripotent stem cell (iPSC) derived neural progenitor cells (NPCs). Here we aimed to determine the impact of infection on the transcriptome in developing human neurons using iPSC-derived 3-dimensional cerebral organoids. We infected iPSC-derived cerebral organoids with HCMV encoding eGFP and sorted cell populations based on GFP signal strength. Significant transcriptional downregulation was observed including in key neurodevelopmental gene pathways in both the GFP (+) and intermediate groups. Interestingly, the GFP (-) group also showed downregulation of the same targets indicating a mismatch between GFP expression and viral infection. Using a modified HCMV virus destabilizing IE 1 and 2 proteins, we still observed significant downregulation of neurodevelopmental gene expression in infected neural progenitor cells. Together, these data indicate that IE viral proteins are not the main drivers of neurodevelopmental gene dysregulation in HCMV infected neural tissues suggesting therapeutically targeting IE gene expression is insufficient to restore neural differentiation and function.

cell biology↗