Ag-inexperienced memory-like T (AIMT) cells are functionally unique T cells, representing one of the two largest subsets of murine CD8+ T cells. However, differences between laboratory inbred strains, insufficient data from germ-free mice, a complete lack of data from feral mice, and an unclear relationship between AIMT cells formation during aging represent major barriers for better understanding of their biology. We performed a thorough characterization of AIMT cells from mice of different genetic background, age, and hygienic status by flow cytometry and multiomics approaches, including analyses of gene expression, TCR repertoire, and microbial colonization. Our data showed that AIMT cells are steadily present in mice, independent of their genetic background and hygienic status. Despite differences in their gene expression profiles, young and aged AIMT cells originate from identical clones. We identified that CD122 discriminates two major subsets of AIMT cells in a strain-independent manner. Whereas thymic CD122LOW AIMT cells (innate memory) prevail only in young animals with high thymic IL-4 production, peripheral CD122HIGH AIMT cells (virtual memory) dominate in aged mice. Cohousing with feral mice changed the bacterial colonization of laboratory strains but had only minimal effects on the CD8+ T cell compartment, including AIMT cells.

Glial cells expressing neuron‐glial antigen 2 (NG2), also known as oligodendrocyte progenitor cells (OPCs), play a critical role in maintaining brain health. However, their ability to differentiate after ischemic injury is poorly understood. The aim of this study was to investigate the properties and functions of NG2 glia in the ischemic brain. Using transgenic mice, we selectively labeled NG2‐expressing cells and their progeny in both healthy brain and after focal cerebral ischemia (FCI). Using single‐cell RNA sequencing, we classified the labeled glial cells into five distinct subpopulations based on their gene expression patterns. Additionally, we examined the membrane properties of these cells using the patch‐clamp technique. Of the identified subpopulations, three were identified as OPCs, whereas the fourth subpopulation had characteristics indicative of cells likely to develop into oligodendrocytes. The fifth subpopulation of NG2 glia showed astrocytic markers and had similarities to neural progenitor cells. Interestingly, this subpopulation was present in both healthy and post‐ischemic tissue; however, its gene expression profile changed after ischemia, with increased numbers of genes related to neurogenesis. Immunohistochemical analysis confirmed the temporal expression of neurogenic genes and showed an increased presence of NG2 cells positive for Purkinje cell protein‐4 at the periphery of the ischemic lesion 12 days after FCI, as well as NeuN‐positive NG2 cells 28 and 60 days after injury. These results suggest the potential development of neuron‐like cells arising from NG2 glia in the ischemic tissue. Our study provides insights into the plasticity of NG2 glia and their capacity for neurogenesis after stroke.

Trophoblastic cell surface antigen 2 (TROP2) is a membrane glycoprotein overexpressed in many solid tumors with a poor prognosis, including intestinal neoplasms. In our study, we show that TROP2 is expressed in preneoplastic lesions, and its expression is maintained in most colorectal cancers (CRC). High TROP2 positivity correlated with lymph node metastases and poor tumor differentiation and was a negative prognostic factor. To investigate the role of TROP2 in intestinal tumors, we analyzed two mouse models with conditional disruption of the adenomatous polyposis coli (Apc) tumor-suppressor gene, human adenocarcinoma samples, patient-derived organoids, and TROP2-deficient tumor cells. We found that Trop2 is produced early after Apc inactivation and its expression is associated with the transcription of genes involved in epithelial–mesenchymal transition, the regulation of migration, invasiveness, and extracellular matrix remodeling. A functionally similar group of genes was also enriched in TROP2-positive cells from human CRC samples. To decipher the driving mechanism of TROP2 expression, we analyzed its promoter. In human cells, this promoter was activated by β-catenin and additionally by the Yes1-associated transcriptional regulator (YAP). The regulation of TROP2 expression by active YAP was verified by YAP knockdown in CRC cells. Our results suggest a possible link between aberrantly activated Wnt/β-catenin signaling, YAP, and TROP2 expression.

Recent studies in humans and rats suggested that increased Na⁺ storage in the skin without parallel water retention may predispose to salt-sensitive hypertension. In the current studies, we compared tissue Na⁺ storage in salt sensitive spontaneously hypertensive rats (SHR) versus salt resistant normotensive Brown Norway (BN-Lx) rats. After salt loading (10 days drinking 1% NaCl solution), the SHR showed significant parallel increase in Na⁺-to-water as well as (Na⁺+K⁺)-to-water ratios suggesting increased storage of osmotically inactive Na⁺ in the skin while no significant changes in skin electrolyte concentrations were observed in BN-Lx rats. SHR rats after salt treatment exhibited a nonsignificant decrease in skin blood capillary number (rarefaction) while BN-Lx rats showed significantly increased skin blood capillary density. Analysis of dermal gene expression profiles in BN-Lx rats after salt treatment showed significant up-regulation of genes involved in angiogenesis and proliferation of endothelial cells contrary to the SHR. Since the skin harbors most of the body’s resistance vessels it is possible that blood capillary rarefaction may lead to increased peripheral resistance and salt sensitivity in the SHR.

Lambda interferons mediate antiviral immunity by inducing interferon-stimulated genes (ISGs) in epithelial tissues. A common variant rs368234815TT/∆G creating functional gene from an IFNL4 pseudogene is associated with the expression of major ISGs in the liver but impaired clearance of hepatitis C. To explain this, we compared Halo-tagged and non-tagged IFNL3 and IFNL4 signaling in liver-derived cell lines. Transfection with non-tagged IFNL3, non-tagged IFNL4 and Halo-tagged IFNL4 led to a similar degree of JAK-STAT activation and ISG induction; however, the response to transfection with Halo-tagged IFNL3 was lower and delayed. Transfection with non-tagged IFNL3 or IFNL4 induced no transcriptome change in the cells lacking either IL10R2 or IFNLR1 receptor subunits. Cytosolic overexpression of signal peptide-lacking IFNL3 or IFNL4 in wild type cells did not interfere with JAK-STAT signaling triggered by interferons in the medium. Finally, expression profile changes induced by transfection with non-tagged IFNL3 and IFNL4 were highly similar. These data do not support the hypothesis about IFNL4-specific non-canonical signaling and point out that functional studies conducted with tagged interferons should be interpreted with caution.

To shed light on the enigmatic origin of the vertebrate head, our study employs an integrated approach that combines single-cell transcriptomics, perturbations in signaling pathways, and cis-regulatory analysis in amphioxus. As a representative of a basal lineage within the chordate phylum, amphioxus retains many characteristics thought to have been present in the common chordate ancestor. Through cell type characterization, we identify the presence of prechordal plate-like, pre-migratory, and migratory neural crest-like cell populations in the developing amphioxus embryo. Functional analysis establishes conserved roles of the Nodal and Hedgehog signaling pathways in prechordal plate-like populations, and of the Wnt signaling pathway in neural crest-like populations’ development. Furthermore, our trans-species transgenic experiments highlight similarities in the regulatory environments that drive neural crest-like and prechordal plate-like developmental programs in both vertebrates and amphioxus. Our findings provide evidence that the key features of vertebrate head development can be traced back to the common ancestor of all chordates.