The upstream stimulatory factor 2 (USF2) is a transcription factor known as a transcriptional activator that binds to E-box motifs in gene promoters. Recently, we reported that USF2 is also a transcriptional repressor of the genes that encode lysosomes and autophagy machinery, and that its deficiency results in the elevation of autophagy. The present study was designed to determine whether the absence of USF2 is responsible for more effective protection of the host cells from bacterial infection and intracellular bacterial growth. In this context, we employed Salmonella enterica serovar Typhimurium (S. Typhimurium) as a model pathogen and monitored the changes in intracellular bacterial burden observed in the wild-type (WT) cells and USF2-deficient cells over the time course of infection. The number of intracellular bacteria increased after infection in WT cells but remained similar or decreased in USF2-deficient cells. This phenomenon was observed in various cell types, including mouse embryonic fibroblasts (MEFs), RAW264.7 macrophage-like cells, and primary bone marrow-derived macrophages (BMDMs). The phagocytosis levels were the same in WT and USF2-deficient macrophages, but the latter had a higher basal autophagy, increased lysosome abundance, and increased expression of lysosomal genes. In addition, the components of LC3-associated phagocytosis (LAP), such as LC3B and RUBICON, together with reactive oxygen species (ROS) production, were elevated in USF2-deficient macrophages. Our results demonstrated that the enhanced autophagy in non-phagocytic cells and the elevated autophagy and LAP in phagocytes both contribute to the improved clearance of intracellular pathogens in USF2-deficient cells.
Natural killer T (NKT) cells are innate-like T lymphocytes that express natural killer (NK) cell receptors (NKRs), which recognize glycolipid antigens presented by the MHC class I-like protein CD1d, linking innate and adaptive immunity. NKT cells include two main subsets, type I and type II, which differ in TCR usage and antigen specificity. In addition, NKT-like cells, which express NKRs but are CD1d-independent, have attracted growing interest in neuroimmunology. These NKR-expressing T cells play important roles in either promoting or suppressing pathological conditions within the brain. This review overviews recent advances in understanding NKT cells in immune disorders of the central nervous system (CNS), including neurodegenerative diseases, neuroinflammation, autoimmune diseases, brain injury, and CNS malignancies, such as glioblastoma. By interacting with CD1d on non-immune cells (e.g. astrocytes) and immune cells (e.g. microglia) through their TCR, type I NKT cells help maintain or disrupt immune homeostasis in the CNS. In addition, exogenous ligands, such as alpha-galactosylceramide, can modify type I and type II NKT cell phenotypes and promote regulatory functions in NKT-like cells, which may mitigate excessive inflammation. This review provides insights into how NKT cell subsets could serve as therapeutic targets for neuroinflammatory diseases.
The overall structure and development of the central nervous system (CNS) are highly conserved among vertebrates. Peak neurogenesis generally precedes the main wave of astrogliogenesis; exuberant synapses are formed and pruned during critical periods; and the neurotransmitter gamma-aminobutyric acid (GABA) shifts from depolarizing to hyperpolarizing as the brain matures. The sequence of these key developmental events is broadly similar across vertebrate model organisms, including mouse, Xenopus, and zebrafish. Despite this overall similarity, the relative duration of each event varies substantially, and key events such as live birth in mammals do not occur in fish or frogs. These differences must be considered when translating findings from one species to another. In this review, we compare several developmental events that are relevant to modeling human diseases in animal models, including microglial colonization and blood–brain barrier formation. We also present comparative developmental timelines as a resource for translational neuroscience research.
Parkinson’s disease (PD) is characterized by nigrostriatal dopaminergic (DAergic) degeneration and motor dysfunction. Many PD patients also show circadian rhythm disturbances. Increasing evidence links circadian clock dysfunction to PD pathology. REV-ERBα is a circadian nuclear receptor that regulates DAergic genes under physiological conditions. However, its role in nigrostriatal dopamine (DA) homeostasis and motor function in PD remains unclear. In this study, we found elevated Rev-erbα mRNA expression in tyrosine hydroxylase (TH)-positive neurons of the substantia nigra (SN) in a 6-hydroxydopamine (6-OHDA) mouse model of PD. To test its functional role, we assessed the acute effects of local SN microinjection of the REV-ERBα antagonist SR8278. We found that SR8278 partially recovered motor performance and improved fine motor function. These effects occurred regardless of circadian timing. SR8278 administration did not restore TH expression or tissue DA levels in the striatum and SN. However, in vivo microdialysis showed enhanced extracellular DA turnover in the striatum. Specifically, while extracellular DA metabolites level increased, basal extracellular DA levels showed no change. Together, these findings identify REV-ERBα as a potential therapeutic target that modulates extracellular nigrostriatal DA dynamics and improves motor function in PD.
Visceral sensory neurons (VSNs) play an essential role in interoception, but it remains challenging to selectively access them using genetic tools due to their anatomical location and shared molecular markers with central autonomic circuits. Although transgenic models visualizing Phox2b-expressing neurons have been developed to genetically label VSNs, concurrent Phox2b expression in the hindbrain limits their selectivity. To overcome these limitations, we engineered several Phox2b promoter-driven adeno-associated virus (AAV) vectors and evaluated the effects of capsid serotype, delivery route, and injection timing. Using systemic delivery of AAV-PHP.S-Phox2b-Cre, we found that postnatal day 8 is an optimal time window for efficient and selective labeling of VSNs with a relatively low dose. The result contrasts with neonatal administration, which led to extensive ectopic labeling at the same dose. Unexpectedly, lingual submucosal delivery of AAV-retro-Phox2b-Cre, initially intended to label tongue-innervating sensory neurons, also labeled most vagal neurons. These labeled neurons were AAV-retro capsid-specific, because local delivery of AAV-PHP.S-Phox2b-Cre labeled cells only near the injection site. Altogether, this study provides practical parameters for selective genetic access to VSNs using AAV.
