Notterman, D. | Search bioRxiv

bioRxiv2025

Social isolation upregulates takeout expression in female Drosophila melanogaster to promote sucrose feeding

Drosophila melanogaster provides a model system to examine how environmental stress interacts with sex to induce changes in brain function and behavior. Previous research suggests that social isolation induces changes in gene expression that encode a starvation-like brain state and reduce sleep. However, the extent to which social isolation alters behaviors via sex-specific brain changes is unclear. Here, we use Drosophila melanogaster to explore sex differences in chronic social isolation-induced behavioral and transcriptomic changes. We focused on takeout (to), a gene encoding a putative juvenile hormone-binding protein, as a target that is upregulated solely in females following social isolation. Male and female adult flies were exposed to chronic social isolation, and multiple behavioral sex differences were identified through tests of activity, motivation, aggression, and sugar consumption. RNA-seq analysis also identified several candidate genes that were associated with sex differences in isolation-induced behavioral changes. Our findings suggest that social isolation is sufficiently stressful to reveal latent sex differences in behavior, despite having no impact on survival. To expression and sucrose consumption were upregulated exclusively in females following social isolation. Following to knockdown in to-expressing cells, sucrose consumption decreased in socially isolated females but increased in males. However, to knock down, to overexpression, and transformer knock down in neurons did not change sucrose-feeding behavior between control and isolated females. Overall, our results suggest that manipulating to expression influences sucrose-feeding in opposite directions between females and males following social isolation, and that isolation-induced to overexpression in non-neuronal cells in the brain or head may play a role in communicating information about females nutritional status to the brain. Additional roles for to in stress-related behaviors and behavioral sex differences should be explored, as well as whether to participates in signaling pathways that may be functionally conserved in human disorders. Author SummaryChronic stress contributes to detrimental health effects, but our understanding of how stress induces sex differences in brain gene expression and behavior is incomplete. Here, we use a combination of behavioral testing, RNA sequencing, and genetic manipulations in Drosophila melanogaster to explore how social isolation reveals latent sex differences in gene expression and stress-relevant behaviors. We found the most pronounced sex differences in behaviors related to feeding and motivation. RNA profiling revealed isolated female-specific upregulation of over 100 genes, with many of them relating to reproduction and energy metabolism. We manipulated expression of the candidate gene takeout (to) and found that downregulating to in all to-expressing cells decreases sucrose-feeding in isolated females but increases it in isolated males. Our results suggest that within a chronic stress context, sex-specific effectors in the head may regulate gene expression related to feeding and macronutrient choice to ensure that females prioritize survival over reproduction. Learning more about this system in flies could provide insight into functionally analogous pathways in humans that may be dysregulated in female-biased stress-related disorders.

neuroscience↗

bioRxiv2024

Proteomic profiling of the local and systemic immune response to pediatric respiratory viral infections

Viral lower respiratory tract infection (vLRTI) is a leading cause of hospitalization and death in children worldwide. Despite this, no studies have employed proteomics to characterize host immune responses to severe pediatric vLRTI in both the lower airway and systemic circulation. To address this gap, gain insights into vLRTI pathophysiology, and test a novel diagnostic approach, we assayed 1,305 proteins in tracheal aspirate (TA) and plasma from 62 critically ill children using SomaScan. We performed differential expression (DE) and pathway analyses comparing vLRTI (n=40) to controls with non-infectious acute respiratory failure (n=22), developed a diagnostic classifier using LASSO regression, and analyzed matched TA and plasma samples. We further investigated the impact of viral load and bacterial coinfection on the proteome. The TA signature of vLRTI was characterized by 200 DE proteins (Padj<0.05) with upregulation of interferons and T cell responses and downregulation of inflammation-modulating proteins including FABP and MIP-5. A nine-protein TA classifier achieved an AUC of 0.96 (95% CI 0.90-1.00) for identifying vLRTI. In plasma, the host response to vLRTI was more muted with 56 DE proteins. Correlation between TA and plasma was limited, although ISG15 was elevated in both compartments. In bacterial coinfection, we observed increases in the TNF-stimulated protein TSG-6, as well as CRP, and interferon-related proteins. Viral load correlated positively with interferon signaling and negatively with neutrophil-activation pathways. Taken together, our study provides fresh insight into the lower airway and systemic proteome of severe pediatric vLRTI, and identifies novel protein biomarkers with diagnostic potential. IMPORTANCEWe describe the first proteomic profiling of the lower airway and blood in critically ill children with severe viral lower respiratory tract infection (vLRTI). From tracheal aspirate (TA), we defined a proteomic signature of vLRTI characterized by increased expression of interferon signaling proteins and decreased expression of proteins involved in immune modulation including FABP and MIP-5. Using machine learning, we developed a parsimonious diagnostic classifier that distinguished vLRTI from non-infectious respiratory failure with high accuracy. Comparative analysis of paired TA and plasma specimens demonstrated limited concordance, although the interferon-stimulated protein ISG15 was significantly upregulated with vLRTI in both compartments. We further identified TSG-6 and CRP as airway biomarkers of bacterial-viral coinfection, and viral load analyses demonstrated positive correlation with interferon-related protein expression and negative correlation with the expression of neutrophil activation proteins. Taken together, our study provides new insight into the lower airway and systemic proteome of severe pediatric vLRTI.

immunology↗