👤 Mónica A Farías

Neurodevelopmental disorders have been increasingly associated with maternal immune activation (MIA) during pregnancy, particularly in response to viral infections. However, the impact of human respiratory syncytial virus (hRSV) infection during gestation on offspring neurodevelopment remains poorly understood. This study aimed to characterize hRSV-induced MIA and evaluate its effects on fetal brain development and offspring behavior using a murine model. Pregnant mice were infected with hRSV at gestational day 14, and tissues were analyzed at day 19. Infection induced pulmonary inflammation, evidenced by increased neutrophil infiltration, and viral replication was detected in maternal lungs and placental tissue, but not in fetal organs. Placental infection was associated with increased decidual immune cells and a shift toward a pro-inflammatory cytokine profile, including elevated IL-6, TNF-α, IFN-γ, and IL-1β, along with decreased IL-10 and IFN-λ. Increased levels of IL-6, TNF-α, and IL-4 were also detected in maternal serum and fetal brains, suggesting vertical transfer of cytokines. Additionally, reduced brain-derived neurotrophic factor levels and altered expression of tight junction-related genes were observed in fetal brains. Behavioral analyses revealed that offspring of infected dams exhibited impaired short-term memory and altered anxiety-like and repetitive behaviors, which persisted or intensified with age. These findings demonstrate that maternal hRSV infection induces MIA, disrupts the fetal neuroimmune environment, and leads to long-term behavioral alterations in offspring, highlighting hRSV as a potential risk factor for neurodevelopmental disorders. Show less

Amyloid precursor protein (APP) is a key player in various neuronal functions but also the source for toxic Aβ that accumulates in the brain of Alzheimer patients. APP trafficking and processing depend on the endo-lysosomal system, but the molecular mechanisms that coordinate these processes remain not fully understood. Here, we studied the HOPS complex, a central regulator of endo-lysosomal maturation. We show that HOPS disruption impairs retromer-mediated recycling of APP to the TGN, resulting in the accumulation of APP in late endosomes. In neurons, this accumulation is spatially restricted to somatodendritic endosomes. These APP-containing endosomes are catalytically inactive and lack the γ-secretase subunit PSEN2. However, they do contain BACE1, which contributes to the build-up of toxic APP C-terminal fragments (APP-CTFs). Notably, loss of HOPS function enhances secretion of APP-CTFs by exosomes, suggesting a potential mechanism for disease propagation. Together, our findings establish a mechanistic link between HOPS loss-of-function and aberrant APP processing, with implications for neurodegeneration. Show less

Phase separation of components of ER exit sites (ERES) into membraneless compartments, the Sec bodies, occurs in Drosophila cells upon exposure to specific cellular stressors, namely, salt stress and amino acid starvation, and their formation is linked to the early secretory pathway inhibition. Here, we show Sec bodies also form in secretory mammalian cells upon the same stress. These reversible and membraneless structures are positive for ERES components, including both Sec16A and Sec16B isoforms and COPII subunits. We find that Sec16A, but not Sec16B, is a driver for Sec body formation, and that the coalescence of ERES components into Sec bodies occurs by fusion. Finally, we show that the stress-induced coalescence of ERES components into Sec bodies precedes ER exit inhibition, leading to their progressive depletion from ERES that become non-functional. Stress relief causes an immediate dissolution of Sec bodies and the concomitant restoration of ER exit. We propose that the dynamic conversion between ERES and Sec body assembly, driven by Sec16A, regulates protein exit from the ER during stress and upon stress relief in mammalian cells, thus providing a conserved pro-survival mechanism in response to stress. Show less