The human gut-brain axis (GBA) is increasingly recognized as a complex bidirectional communication system integrating microbial, neural, endocrine, and immune networks that shape neurological health. While bacterial contributions to this dialogue have been extensively characterized, the viral component of the gut ecosystem, the virome, has emerged as an important component associated with host physiological regulation. This review synthesizes evidence suggesting that bacteriophages and eukaryotic viruses may contribute to microbial and immune homeostasis and may influence signaling along the microbiota–gut–brain axis. In experimental studies, Bacteriophages have been shown to influence microbial community structure through lytic and lysogenic cycles, horizontal gene transfer, and metabolic modulation, indirectly regulating production of neuroactive metabolites such as short-chain fatty acids and tryptophan derivatives which in turn have been linked to blood brain barrier integrity and modulate microglial activation. In observational human studies and experimental models, eukaryotic viruses including Epstein Barr virus and cytomegalovirus have been associated with systemic inflammation, molecular mimicry, and cytokine dysregulation, amplifying neuroimmune cascades implicated in Alzheimer’s disease (AD), multiple sclerosis (MS), autism spectrum disorder (ASD), and major depressive disorder (MDD). The convergence of viral-bacterial interactions highlights a transkingdom signaling network shaping neuroinflammatory tone and influencing disease susceptibility. Emerging experimental strategies, including precision phage therapy, engineered probiotics incorporating CRISPR-based antiviral systems, and fecal virome transplantation (FVT), are being explored as potential approaches to modulate virome–microbiome interactions. Integration of multiomics platforms with artificial intelligence–driven modeling will be critical for clarifying the temporal and mechanistic relationships between virome dynamics and neurological function. Collectively, these insights highlight the gut virobiome as a potentially important contributor to neuroimmune equilibrium and illuminate avenues for microbiome-informed diagnostics and interventions in neurodegenerative and neuropsychiatric disorders. This review therefore highlights the often underappreciated role of the gut virobiome and proposes an integrative conceptual model linking virome dynamics with microbiota–gut–brain axis signaling.
Cajal-Retzius neurons (CRN) represent an early-born transient neuronal population in the mammalian neocortex. They are best known for secreting reelin, which is essential for neuronal migration and layer formation in the developing cortex. However, their functional integration into developing cortical circuits and their contribution to early network dynamics have been poorly understood. In this study, we investigated the structural and functional integration of CRN into developing neocortical networks with immunohistochemistry, three-dimensional reconstruction of GABAergic inputs, extracellular electrophysiology and calcium imaging. In addition, multiplexed FISH was used to determine the expression levels of the chloride transporters NKCC1 and KCC2 in CRN at different postnatal stages. Finally, we employed optogenetic stimulation to assess the functional and developmental consequences of CRN activation. We found that CRN receive dense dendritic GABAergic synaptic inputs at early postnatal stages. Functional analyses revealed that a substantial fraction of CRN is spontaneously active, and that their activity is synchronized with both CRN and non-CRN neurons. At the molecular level, they display a persistent NKCC1-dominant expression profile. This profile can contribute to the excitatory GABA responses, but also affect their cell death, as chronic blockade of NKCC1 was associated with reduced CRN loss in vitro. Acute optogenetic activation of CRN at early stages increased network excitability in organotypic neocortical cultures and induced stimulus-evoked field responses, while chronic activation at later time points accelerated CRN loss. Overall, these findings demonstrate that, during development, dense GABAergic input connectivity, coupled with the putative excitatory action of GABA, can engage CRN in early network activity. Furthermore, not only do CRN actively participate in early immature circuits, but their activity also amplifies spontaneous network dynamics and contributes to their own transience, highlighting a potential novel functional role of CRN during neocortical development.
Abstract Vesicular membrane trafficking is central to eukaryotic homeostasis, governing receptor downregulation, lysosomal degradation, and intercellular communication via exosomes. These processes are classically explained by SNARE-mediated fusion and ESCRT-dependent membrane remodeling, which together define current models of vesicle biogenesis and multivesicular body (MVB) formation. Recent high-resolution cryo-electron tomography of intact mammalian cells has identified a structurally distinct membrane-associated assembly termed the hemifusome. Hemifusomes consist of two heterotypic vesicles connected by a persistent hemifusion diaphragm (~ 160 nm in diameter) and feature a ~ 42 nm proteolipid nanodroplet (PND) localized at the diaphragm rim. This architecture expands current views of hemifusion intermediates and raises the possibility of an alternative mode of endosomal membrane organization distinct from canonical ESCRT-mediated processes. However, the molecular composition, biogenesis, and regulatory mechanisms of this system remain undefined. Here, we provide the first integrated synthesis of hemifusome and PND biology, consolidating structural, biophysical, and mechanistic observations within the context of endosomal trafficking. We compare this emerging framework with ESCRT-mediated intraluminal vesicle formation, highlighting both shared features and key mechanistic gaps. We further examine preliminary and largely correlative links to neurodegenerative and lysosomal storage disorders, while emphasizing the absence of direct causal evidence. Given that this field currently rests on a single primary research report, we deliberately separate this evidence-based structural synthesis from more speculative functional, disease-related, and translational extensions, which are presented as explicit future perspectives rather than established conclusions. Finally, we outline unresolved questions, including PND molecular identity, determinants of hemifusion diaphragm organization and stability, and the temporal sequence of hemifusome assembly and remodeling. Together, these findings position hemifusomes as a potentially distinct structural state within the endosomal network, warranting systematic molecular and functional investigation.
BACKGROUND:Although endurance exercise benefits liver health, sex-specific adaptive trajectories remain unclear. This study mapped dynamic liver adaptation in males and females during prolonged training and identified underlying molecular programs. METHODS:Using publicly available time-resolved liver multi-omics data generated by the Molecular Transducers of Physical Activity Consortium (MoTrPAC), we established a computational pipeline for differential analysis of transcriptomic, proteomic, phosphoproteomic, and metabolomic data with FDR correction, followed by FGSEA pathway enrichment. Kinase activities were inferred through ortholog mapping and PhosphoSitePlus. Cross-omics co-expression networks were constructed using WGCNA and topological overlap to link omics features with physiological phenotypes. For experimental validation, liver tissues were collected from endurance-trained Sprague-Dawley rats, and key nodes were confirmed by Western blotting, qRT-PCR, and immunofluorescence/immunohistochemical staining. Public scRNA-seq data were further integrated to map multi-omics signals to single-cell resolution and assess functional changes in specific cell types. RESULTS:The hepatic response to exercise stress was stage-specific, shifting from early transcriptional activation to later proteomic and metabolic remodeling. Multi-omics integration revealed distinct sex-associated adaptive trajectories: males were more strongly associated with energy metabolism, redox-related programs, and amino acid/organic acid catabolism, whereas females showed prominent membrane lipid remodeling, proteostasis -related programs, and mitochondrial/ribosomal translational features. Single-cell analysis showed that tissue remodeling occurred without major lineage turnover, instead involving altered communication among pre-existing cell communities. Validation of PPP1R3G identified a protein-dominant exercise-responsive marker, supporting the contribution of post-transcriptional or protein-level regulation. CONCLUSIONS:Hepatic adaptation to endurance stress follows a cross-omics evolutionary pattern with sex-specific reprogramming of energy supply and homeostatic maintenance. This time-resolved framework clarifies how exercise improves liver function and supports sex-oriented metabolic interventions and therapeutic target discovery.
Abstract Unlike adult hearts, neonatal hearts can regenerate and adapt to stress. To identify both cardioprotective and regenerative mechanisms, we compared activated genes and related signaling pathways in the neonatal mouse heart after myocardial infarction (MI) and after exposure to pressure overload using a neonatal model of transverse aortic constriction (nTAC) at postnatal day 1 (P1). We identified three immune-related genes—Ccl4, S100a8, and C1qa—of high interest, as they encode secreted factors, are highly expressed in the neonatal mouse heart in both injury types, and their receptors are expressed on neonatal cardiomyocytes (nCM) and cardiac endothelial cells (EC). We investigated their effects on primary mouse EC and nCM in vitro. Our study found that the combination of these secreted factors (Pool3) enhances EC and nCM cell cycle re-entry and reduces the rate of apoptosis. Combined in vivo and in vitro transcriptome analyses revealed that Toll-like receptor 2 (TLR2) activation in nCM induces a shared pro-survival and cell cycle re-entry-associated signaling, including upregulation of Bcl2 and Birc5, respectively. The direct and pivotal role of TLR2 in enhancing nCM cell cycle re-entry and survival was further confirmed using TLR2 knockout (KO) nCM, a TLR2 inhibitor, and a TLR2 agonist (zymosan). Moreover, the importance of TLR2 in mediating the adaptive response to pressure overload in neonatal mice was confirmed in TLR2 KO mice, which failed to adapt to pressure overload and exhibited high mortality together with maladaptive cardiac remodeling as early as 7 days post-surgery. Collectively, these findings demonstrate that TLR2 is essential for mediating nCM cell cycle re-entry, survival, and adaptive/regenerative response to injury. Graphical Abstract Schematic image of immune-cardiomyocyte crosstalk via TLR2 during cardiac injury in neonatal mice. TLR2 activation in response to secreted immune cytokines such as CCL4, C1QA, and S100A8 during cardiac injury promotes nCM survival and cell cycle re-entry via upregulation of Bcl2 and Birc5, respectively
