Biology subjects

Sanders, A.

Publications and source records attributed to Sanders, A..

7 recordsLinked to original sources

bioRxiv2026

Live immunogenic melanoma cells generated by etoposide treatment upregulate B2M and lose tumor-forming potential

Cytotoxic chemotherapy has been the primary cancer treatment modality for decades, however, chemotherapy drugs do not selectively target cancer cells. These drugs are toxic to all proliferating cells including immune cells that constitute the host-defense system against pathogens and cancer cells. In an effort to develop non-toxic combinations of chemotherapy and immunotherapies for cancer, we previously reported in Sriram et al. 2021 that etoposide-treated B16 melanoma cells expressing ovalbumin, when co-cultured in vitro with dendritic cells and T-cells, enhance T-cell activation. The live fraction of melanoma cells after etoposide treatment was critical to promote T-cell activation as dead cells alone or in combination with cell-free supernatants were not effective. In this study, we show that the live fraction of etoposide-treated B16-Ova cells, which gain the ability to stimulate T-cells, are growth-arrested, but remain viable past the co-incubation period with dendritic cells and T-cells post etoposide washout. Furthermore, using a soft-agar colony-formation assay as a proxy for tumor-forming potential, we show that these live etoposide-treated B16-Ova cells have drastically reduced ability to form colonies displaying a near-complete loss of anchorage-independent growth. We also show that etoposide treatment upregulates the production of Beta-2-microglobulin (B2M), a subunit of Class I MHC. Intriguingly, we observed using immunofluorescence that the live etoposide-treated B16-Ova cells show enhanced intracellular perinuclear B2M accumulation but B2M surface staining, while detectable, is not enhanced by etoposide treatment. Furthermore, while the live etoposide-treated B16-Ova cells express Class I MHC protein, there is only a marginal drug treatment-induced increase observed in the expression levels by western blotting. Our results suggest that T-cell activation by live etoposide-treated B16-Ova cells is likely not driven by drug treatment-induced enhancement in cell surface levels of Class I MHC and point to other mechanisms.

cancer biology↗

bioRxiv2025

Population structure of Phytophthora infestans collected from potatoes in Guatemala and Honduras

Phytophthora infestans, the causal agent of late blight, remains a major constraint to potato production worldwide. In Central America, particularly in Guatemala and Honduras, information on the pathogen's population structure is limited despite its economic importance and reliance on imported seed potatoes. This study characterized the population structure of P. infestans in potato fields in Guatemala and Honduras using microsatellite markers, mitochondrial haplotypes, and mating type analyses. Four SSR-defined groups were identified, three corresponding to the previously described clonal lineages EU13A2, NI_1, and US8A2, and one putative group designated CeA (Central America). The detection of EU13A2, a lineage first reported in Europe and subsequently in Asia, indicates its establishment in Central America. All successfully characterized isolates exhibited the Ia mitochondrial haplotype, indicating limited mitochondrial diversity despite substantial nuclear SSR variation. AMOVA revealed significant genetic differentiation between Honduras and Guatemala, accounting for 24.43% of the total SSR variation (p = 0.022). Significant linkage disequilibrium was detected within the analyzed populations. The occurrence of genetically distinct P. infestans groups across the study area highlights the importance of monitoring transboundary pathogen movement in Central America.

pathology↗

bioRxiv2024

Opioid-driven disruption of the septal complex reveals a role for neurotensin- expressing neurons in withdrawal

Because opioid withdrawal is an intensely aversive experience, persons with opioid use disorder (OUD) often relapse to avoid it. The lateral septum (LS) is a forebrain structure that is important in aversion processing, and previous studies have linked the lateral septum (LS) to substance use disorders. It is unclear, however, which precise LS cell types might contribute to the maladaptive state of withdrawal. To address this, we used single-nucleus RNA-sequencing to interrogate cell type specific gene expression changes induced by chronic morphine and withdrawal. We discovered that morphine globally disrupted the transcriptional profile of LS cell types, but Neurotensin-expressing neurons (Nts; LS-Nts neurons) were selectively activated by naloxone. Using two-photon calcium imaging and ex vivo electrophysiology, we next demonstrate that LS-Nts neurons receive enhanced glutamatergic drive in morphine-dependent mice and remain hyperactivated during opioid withdrawal. Finally, we showed that activating and silencing LS-Nts neurons during opioid withdrawal regulates pain coping behaviors and sociability. Together, these results suggest that LS-Nts neurons are a key neural substrate involved in opioid withdrawal and establish the LS as a crucial regulator of adaptive behaviors, specifically pertaining to OUD.

neuroscience↗

bioRxiv2023

The helminth TGF-beta mimic TGM4 is a modular ligand that binds CD44, CD49d and TGF-beta receptors to preferentially target myeloid cells

The murine helminth parasite Heligmosomoides polygyrus expresses a family of modular proteins which, replicating the functional activity of the immunomodulatory cytokine TGF-{beta}, have been named TGM (TGF-{beta} Mimic). Multiple domains bind to different receptors, including TGF-{beta} receptors T{beta}RI (ALK5) and T{beta}RII through domains 1-3, and prototypic family member TGM1 binds the cell surface co-receptor CD44 through domains 4-5. This allows TGM1 to induce T lymphocyte Foxp3 expression, characteristic of regulatory (Treg) cells, and to activate a range of TGF-{beta}-responsive cell types. In contrast, a related protein, TGM4, targets a much more restricted cell repertoire, primarily acting on myeloid cells, with less potent effects on T cells and lacking activity on other TGF-{beta}-responsive cell types. TGM4 binds avidly to myeloid cells by flow cytometry, and can outcompete TGM1 for cell binding. Analysis of receptor binding in comparison to TGM1 reveals a 10-fold higher affinity than TGM1 for TGF{beta}R-I (T{beta}RI), but a 100-fold lower affinity for T{beta}RII through Domain 3. Consequently, TGM4 is more dependent on co-receptor binding; in addition to CD44, TGM4 also engages CD49d (Itga4) through Domains 1-3, as well as CD206 and Neuropilin-1 through Domains 4 and 5. TGM4 was found to effectively modulate macrophage populations, inhibiting lipopolysaccharide-driven inflammatory cytokine production and boosting interleukin (IL)-4-stimulated responses such as Arginase-1 in vitro and in vivo. These results reveal that the modular nature of TGMs has allowed the fine tuning of the binding affinities of the T{beta}R- and co-receptor binding domains to establish cell specificity for TGF-{beta} signalling in a manner that cannot be attained by the mammalian cytokine.

immunology↗

bioRxiv2023

Overexpression of MUC1 influences the anti-proliferative effect of STAT3-inhibitor Napabucasin in epithelial cancers.

MUC1 is a transmembrane glycoprotein that is overexpressed and aberrantly glycosylated in epithelial cancers. The cytoplasmic tail of MUC1 (MUC1 CT) aids in tumorigenesis by upregulating the expression of multiple oncogenes. Signal transducer and activator of transcription 3 (STAT3) plays a crucial role in several cellular processes and is aberrantly activated in many cancers. In this study, we focus on recent evidence suggesting that STAT3 and MUC1 regulate each others expression in cancer cells in an auto-inductive loop and found that their interaction plays a prominent role in mediating epithelial-to-mesenchymal transition (EMT) and drug resistance. The STAT3 inhibitor Napabucasin was in clinical trials but was discontinued due to futility. We found that higher expression of MUC1 increased the sensitivity of cancer cells to Napabucasin. Therefore, high-MUC1 tumors may have a better outcome to Napabucasin therapy. We report how MUC1 regulates STAT3 activity and provide a new perspective on repurposing the STAT3-inhibitor Napabucasin to improve clinical outcome of epithelial cancer treatment.

cancer biology↗

bioRxiv2021

Graded variation in cortical T1w/T2w myelination during adolescence

Myelination influences brain connectivity during sensitive periods of development by enhancing neural signaling speed and regulating synapse formation to reduce plasticity. However, in vivo studies characterizing the maturational timing of cortical myelination during human development remain scant. Here, we take advantage of recent advances in high-resolution cortical T1w/T2w myelin mapping methods, including principled correction of B1+ transmit field effects, using data from the Human Connectome Project in Development (N=628, ages 8-21) to characterize the maturational timing of myelination from childhood through early adulthood throughout the cerebral neocortex. We apply Bayesian spline models and functional latent clustering analysis to demonstrate graded variation in the rate of cortical T1w/T2w myelin growth in neocortical areas that is strongly correlated with the sensorimotor-association (S-A) axis of cortical organization reported by others. In sensorimotor areas T1w/T2w myelin starts at high levels at early ages, increases at a fast pace, and decelerates at later ages (18-21). In intermediate multimodal areas along the S-A axis, T1w/T2w myelin tends to start at intermediate levels and increase linearly at an intermediate pace. In transmodal/paralimbic association areas high along the S-A axis, T1w/T2w myelin tends to start at low levels and increase linearly at the slowest pace. These data provide evidence for graded variation along the S-A axis in the rate of cortical myelination during adolescence, which could reflect ongoing plasticity underlying the development of complex information processing and psychological functioning. Significance StatementMyelin is a lipid membrane that is essential to healthy brain function. Myelin wraps axons to increase neural signaling speed, enabling complex neuronal functioning underlying learning and cognition. Here we characterize the developmental timing of myelination across the cerebral cortex during adolescence using recent advances in non-invasive myelin mapping. Our results provide new evidence demonstrating graded variation across the cortex in the timing of myelination during adolescence, with rapid myelination in lower-order sensory areas and gradual myelination in higher-order association areas. This spatial pattern of microstructural brain development closely parallels the sensorimotor-to-association axis of cortical organization and plasticity during ontogeny.

neuroscience↗

bioRxiv2018

CONSTRUCTION OF WHOLE GENOMES FROM SCAFFOLDS USING SINGLE CELL STRAND-SEQ DATA

Accurate reference genome sequences provide the foundation for modern molecular biology and genomics as the interpretation of sequence data to study evolution, gene expression and epigenetics depends heavily on the quality of the genome assembly used for its alignment. Correctly organising sequenced fragments such as contigs and scaffolds in relation to each other is a critical and often challenging step in the construction of robust genome references. We previously identified misoriented regions in the mouse and human reference assemblies using Strand-seq, a single cell sequencing technique that preserves DNA directionality1, 2. Here we demonstrate the ability of Strand-seq to build and correct full-length chromosomes, by identifying which scaffolds belong to the same chromosome and determining their correct order and orientation, without the need for overlapping sequences. We demonstrate that Strand-seq exquisitely maps assembly fragments into large related groups and chromosome-sized clusters without using new assembly data. Using template strand inheritance as a bi-allelic marker, we employ genetic mapping principles to cluster scaffolds that are derived from the same chromosome and order them within the chromosome based solely on directionality of DNA strand inheritance. We prove the utility of our approach by generating improved genome assemblies for several model organisms including the ferret, pig, Xenopus, zebrafish, Tasmanian devil and the Guinea pig.

genomics↗