Biology subjects

Negatu, S. G.

Publications and source records attributed to Negatu, S. G..

5 recordsLinked to original sources

bioRxiv2025

Neutral lipid processing in glia is sexually dimorphic and promotes sleep through diacylglycerol catabolism

Sleep is thought to have a protective role in clearing toxic waste from the brain, which may include processing of damaged lipids. We recently showed that blocking endocytosis in glia increases sleep and report here that this block is associated with an increase in peroxidized lipids and glial lipid droplet accumulation, raising the possibility that accumulation of these lipids increases the need to sleep. Sleep gain induced by blocking glial transport is exaggerated by knockout of the lipid droplet coat protein, Lipid Storage Droplet 2 (Lsd2), suggesting that sleep-promoting lipids are not contained in lipid droplets. To identify lipids regulated by sleep state, we performed global, targeted lipidomics analysis on Drosophila neurons and glia, screening nearly 3,000 lipids across 11 major classes. This revealed that sex influences lipid composition in both cell types and lipid homeostasis following extended wakefulness. Female neurons and glia are enriched in ultra-long chain fatty acids, triacylglycerols, and diacylglycerols, with glial diacylglycerol enrichment correlating with elevated sleep need. Based on manipulations of neutral lipid metabolic pathways, we propose that monoacylglycerols, products of glial diacylglycerol catabolism, promote sleep.

neuroscience↗

bioRxiv2025

Interleukin-27 is antiviral at the maternal-fetal interface.

Congenital viral infections can have severe consequences for pregnancy and fetal outcomes. Remarkably, the fetal-derived placenta serves as a robust barrier to infection through meticulous regulation by immune effectors and a diverse repertoire of cytokines. Yet, the regulatory roles of many cytokines remain undefined at the maternal-fetal interface. Interleukin 27 (IL-27) is a highly expressed cytokine in the placenta whose functional consequence during congenital infection is unknown. Here, we utilized trophoblast organoids (TO) derived from primary human placentas and a mouse model of congenital viral infection to uncover the functional role of IL-27 signaling during pregnancy. We show that TOs constitutively express IL-27 and its receptor, IL27RA, and demonstrate that IL-27 signaling restricts Zika virus (ZIKV) infection of TOs. Through bulk RNA-sequencing of TOs in the absence and presence of IL-27 signaling, we demonstrate IL-27-mediated upregulation of antiviral genes. Finally, we show that IL-27 signaling is critical within the context of congenital murine ZIKV infection, as IL-27 restricts placental ZIKV burdens and protects against pathologic fetal outcomes early in gestation. These findings collectively demonstrate a novel role for IL-27 in the placenta and establish IL-27 as an innate antiviral defense at the maternal-fetal interface during congenital viral infection.

microbiology↗

bioRxiv2024

Antiviral immunity within neural stem cells distinguishes viral strain differences in forebrain organoids

Neural stem cells have intact innate immune responses that protect them from virus infection and cell death. Yet, viruses can antagonize such responses to establish neuropathogenesis. Using a forebrain organoid model system at two developmental time points, we identified that neural stem cells, in particular radial glia, are basally primed to respond to virus infection by upregulating several antiviral interferon-stimulated genes. Infection of these organoids with a neuropathogenic Enterovirus-D68 strain, demonstrated the ability of this virus to impede immune activation by blocking interferon responses. Together, our data highlight immune gene signatures present in different types of neural stem cells and differential viral capacity to block neural-specific immune induction.

immunology↗

bioRxiv2024

Neuronal interactions in forebrain organoids lead to protective antiviral responses

Neurotropic viruses are the most common cause of infectious encephalitis and largely target neurons for infection. Our understanding of intrinsic neuronal innate immune response capacity to mediate protective antiviral responses remains incomplete. Here, we evaluated the role of intercellular crosstalk in mediating intrinsic neuronal immunity and its contribution to limiting viral infection. We found that in the absence of viral antagonism, neurons transcriptionally induce robust interferon signaling and can effectively signal to neighboring uninfected bystander neurons. Yet, in two-dimensional cultures, this dynamic response did not restrict viral spread. Interestingly, this differed in the context of viral infection in three-dimensional forebrain organoids with complex neuronal interactions, where we observed protective capacity. We show antiviral crosstalk between infected neurons and bystander neural progenitors is mediated by type I interferon signaling. Using spatial transcriptomics, we then uncover distinct regions of bystander progenitor interactions that reveal critical underpinnings of protective antiviral responses, including expression of distinct antiviral genes. These findings underscore the importance of intercellular communication in protective antiviral immunity in the brain and implicate key contributions to protective antiviral signaling.

immunology↗

bioRxiv2024

Type I interferon alters invasive extravillous trophoblast function.

Inappropriate type I interferon (IFN) signaling during embryo implantation and placentation is linked to poor pregnancy outcomes. Here, we evaluated the consequence of elevated type I IFN exposure on implantation using a biomimetic model of human implantation in an organ-on-a-chip device. We found that type I IFN reduced extravillous trophoblast (EVT) invasion capacity. Analyzing single-cell transcriptomes, we uncovered that IFN truncated endovascular EVT emergence in the implantation-on-a-chip device by stunting EVT epithelial-to-mesenchymal transition. Disruptions to the epithelial-to-mesenchymal transition is associated with the pathogenesis of preeclampsia, a life-threatening hypertensive disorder of pregnancy. Strikingly, unwarranted IFN stimulation induced genes associated with increased preeclampsia risk and a preeclamptic gene-like signature in EVTs. These dysregulated EVT phenotypes ultimately reduced EVT-mediated endothelial cell vascular remodeling in the implantation-on-a-chip device. Overall, our work indicates IFN signaling can alter EVT epithelial-to-mesenchymal transition progression which results in diminished EVT-mediated spiral artery remodeling and a preeclampsia gene signature upon sustained stimulation. Our work implicates unwarranted type I IFN as a maternal disturbance that can result in abnormal EVT function that could trigger preeclampsia.

immunology↗