Biology subjects

Schaefer, L.

Publications and source records attributed to Schaefer, L..

6 recordsLinked to original sources

bioRxiv2026

Preclinical Evaluation of a Novel BOC-Modified Triazoloacridinone (TRA-01AR) in Combination with 5-Fluorouracil in Colorectal Cancer

5-Fluorouracil (5-FU) remains a cornerstone of colorectal cancer (CRC) therapy, yet its clinical efficacy is limited by resistance, systemic toxicity, and unfavorable pharmacokinetics. Strategies that enhance tumor sensitivity while maintaining tolerability are therefore of considerable interest. Here, we evaluated 5-FU in combination with two triazoloacridinones, C-1305 and a novel BOC-modified derivative, TRA-01AR, using integrated cellular, transcriptomic, bioenergetic, and in vivo approaches. Both compounds induced cytotoxic effects across cancer cell models and produced overlapping but distinct transcriptional responses, primarily affecting DNA replication and cell cycle pathways. Bioenergetic profiling revealed a shift toward oxidative phosphorylation accompanied by reduced glycolysis, indicating modulation of cellular metabolism relevant to chemotherapy response. Interestingly, TRA-01AR exhibited delayed cytotoxicity relative to C-1305, although the underlying mechanism remains to be defined. In vivo, the combination of 5-FU with C-1305 significantly reduced tumor weight in HT-29 xenografts, whereas 5-FU combined with TRA-01AR did not result in a statistically significant reduction compared to 5-FU alone. TRA-01AR was associated with a more favorable systemic profile and increased intratumoral blood flow compared with C-1305. Collectively, these findings indicate that triazoloacridinones modulate transcriptional and metabolic programs relevant to the 5-FU response. While C-1305 demonstrated greater antitumor activity under the tested conditions, TRA-01AR exhibited distinct biological effects, including improved tolerability and vascular modulation. Further studies are required to clarify TRA-01AR's mechanism of action and assess its potential relevance in CRC-specific therapies.

pharmacology and toxicology↗

bioRxiv2026

HIF1A-AS2 Regulates Hypoxia-Driven HIF Isoform Switching in Human Endothelial Cells

Hypoxia-inducible factors (HIFs) are central regulators of cellular adaptation to low oxygen, with a well-documented transition from HIF-1 to HIF-2 signaling during prolonged hypoxia. Here, we investigate the role of a natural antisense transcript of HIF1A, HIF1A-AS2, in modulating this transition in human endothelial cells (ECs). Genome-wide expression profiling revealed a strong hypoxia-induced upregulation of HIF1A-AS2 that coincided with a marked reduction in HIF1A mRNA levels, whereas EPAS1 remained stable. Interestingly, this negative correlation was consistent across multiple EC types and supported by silencing experiments which demonstrated that both HIF-1 and HIF-2 contribute to HIF1A-AS2 induction. Knockdown of HIF1A-AS2 partially restored HIF1A expression and increased HIF-1 protein and functional activity, as evidenced by elevated VEGFA and GLUT1 expression. Genomic analysis identified HIF-1 and HIF-2 binding motifs upstream of HIF1A-AS2, supporting the dual regulation. Furthermore, cancer tissue analysis revealed frequent downregulation of HIF1A-AS2, correlating with elevated HIF1A and EPAS1 levels. These findings suggest that HIF1A-AS2 acts as a hypoxia-responsive regulator that limits HIF-1 signaling and facilitates the HIF isoform switch, and suggests implications for endothelial adaptation, angiogenic signaling, and vascular remodeling under chronic hypoxia.

molecular biology↗

bioRxiv2026

Mechanisms of CD4+ T tolerance to a corneal epithelial neoantigen

Tissue-specific peripheral tolerance mechanisms are essential to prevent autoimmunity. The cornea is immune privileged, and anterior chamber-associated immune deviation (ACAID) governs its inner surface. However, the mechanisms that apply to corneal epithelial (outer surface) antigens remain unknown. Using an inducible, cornea-restricted neoantigen mouse model, we found that the cornea relies on inducible regulatory T cells (Tregs) rather than ignorance or ACAID for its epithelial antigens. Although the cornea is both avascular and alymphatic, its epithelial antigens are still efficiently presented by ocular surface-derived antigen-presenting cells to T cells in draining lymph nodes under homeostatic conditions, leading to conventional antigen-specific Treg expansion without ocular pathology. This tolerance was not absolute: systemic immunization redirected antigen-specific responses toward pathogenic effector T cells that disrupted epithelial barrier function. These findings identify Treg induction as a dominant mechanism of corneal epithelial immune homeostasis and demonstrate that inflammatory priming can render a tolerated corneal antigen into an autoimmune target, providing mechanistic insight into dry eye pathogenesis. SummaryThis study shows that immune tolerance to corneal epithelial neoantigens relies not on immune privilege but on peripherally induced regulatory T cells in the draining lymph nodes that can be subverted by innate activation, shedding light on ocular surface disease pathophysiology.

immunology↗

bioRxiv2026

Autoimmune CD4+T cells Cause Meibomian Gland Dysfunction

Sjogren disease (SjD) is an autoimmune disease driven by autoreactive CD4+T cells that leads to an immune-mediated loss of lacrimal glands. Meibomian glands are lipid-producing glands in the eyelids that help prevent tear evaporation. While the role of T cells in lacrimal gland-mediated destruction is well established, it is unknown whether pathogenic T cells can cause MG dysfunction (MGD). Herein, we investigated whether autoreactive CD4+T cells induce MGD and characterized the pathophysiologic mechanisms using an adoptive transfer model. T cells were isolated from CD25KO (CD4KO) or wild-type (CD4WT) mice, transferred into Rag1KO mice. Further, CD4KO cells were co-adoptively transferred with WT regulatory T cells (CD4KO+TregsWT). Our results demonstrate that CD4KO recipients had MG dropout, CD4+IFN-{gamma}+ infiltration, increased MHC II presentation within the periglandular area, MG fibrosis, and decreased lipid production and upregulation of pathways related to inflammation, including Type II interferon signaling. Rag1KO, CD4WT, and CD4KO+TregsWT recipients exhibited minimal inflammation in the periglandular MG area. These results indicate that autoimmune CD4+T cells are sufficient to cause MGD, and healthy young regulatory T cells can prevent T-cell-mediated damage. Taken together, our findings provide mechanistic insights into the pathogenesis autoimmune SjD, and could impact how patients are managed in the clinic.

pathology↗

bioRxiv2025

Monocyte Dysregulation Defines an MDD-Specific Transcriptional Signature Closely Linked to Clinical MDD Traits

ObjectiveMajor depressive disorder (MDD) is a highly heterogeneous psychiatric condition contributing significantly to the global disease burden. In a subset of MDD patients inflammatory processes accompany the disease and this has also been reported for other psychiatric conditions like schizophrenia (SZ). However, little is known regarding immune deregulation in relation to clinical symptoms. MethodsCellular indexing of transcriptomes and epitopes by sequencing (CITE-Seq) of peripheral blood mononuclear cells (PBMCs) from patients with MDD (n=22), SZ (n=10), and healthy controls (HCs, n=26) was performed, yielding 633,284 high-quality single-cell profiles. Differential gene expression, cell composition, pathway enrichment, and weighted gene co-expression network analyses were conducted. MDD symptom severity was assessed using the Beck Depression Inventory-II (BDI-II), enabling the correlation of gene expression with individual disease symptoms. ResultsWe identified disease-specific transcriptomic signatures for MDD as well as for SZ and shared gene expression changes between the two conditions. For MDD, monocyte numbers were elevated concomitant with a strong enrichment of interferon signaling. The MDD-specific signature involving all peripheral cell types correlated strongly with key symptoms of depression like sadness or pessimism. Reactome analysis identified nuclear factor kappa-light-chain-enhancer of activated B cells (NF-{kappa}B)-associated pathways among the genes positively correlating with disease symptoms and traits. ConclusionOur findings might help to stratify psychiatric patients and provide a multidimensional framework for investigating immune contributions to psychiatric disorders and highlight potential targets for therapeutic intervention. Clinical symptoms might be reflected on a molecular level paving the way for more targeted and effective interventions.

genomics↗

bioRxiv2025

Protein dynamics affect O2-stability of Group B -hydrogenase from Thermosediminibacter oceani

In the pursuit of sustainable green energy generation, [FeFe]-hydrogenases have attracted significant attention due to their ability to catalyze hydrogen production. However, the sensitivity of these enzymes to O2 is a major obstacle for their application as biocatalysts in energy conversion technologies. In the search for an O2-stable [FeFe]-hydrogenase, we identified the hydrogenase ToHydA from Thermosediminibacter oceani that belongs to the rarely characterized Group B (M2a) [FeFe]-hydrogenases. Our findings demonstrate that ToHydA exhibits remarkable O2-stability, even under prolonged O2 exposure. By characterizing site-directed mutagenesis variants, we found that the highly conserved proton-transporting cysteine protects H-cluster from O2-induced degradation by forming Hinact state. The additional cysteine residue in the TSCCCP motif of ToHydA, a feature unique to Group B (M2a) [FeFe]-hydrogenases, enhances the flexibility of that motif and facilitates the formation of the Hinact state. Moreover, ToHydA possesses unique features, including the formation of an unusual Hinact resting state that distinguishes the enzyme from other [FeFe]-hydrogenases. Our atomistic molecular dynamics simulations reveal a previously unrecognized cluster of hydrophobic residues centered around the proton-transporting cysteine-bearing loop. This structural feature appears to be a common molecular characteristic in hydrogenases that form the O2-protected Hinact state. By exploiting these molecular features of ToHydA, future research can aim to rationally design hydrogenases that combine high catalytic activity with enhanced O2 stability, to develop more efficient and durable catalysts. Table of Contents Figure O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=153 SRC="FIGDIR/small/643706v1_ufig1.gif" ALT="Figure 1"> View larger version (61K): org.highwire.dtl.DTLVardef@96b4aorg.highwire.dtl.DTLVardef@62f367org.highwire.dtl.DTLVardef@59f170org.highwire.dtl.DTLVardef@fa2fd7_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗