Biology subjects

Jansen, L.

Publications and source records attributed to Jansen, L..

12 recordsLinked to original sources

bioRxiv2026

Lineage-associated tumor cell states predict outcome and guide immunotherapeutic target selection in pediatric osteosarcoma

Osteosarcoma is a highly heterogeneous primary bone malignancy that predominantly affects adolescents and young adults, and robust prognostic biomarkers and effective targeted therapies remain lacking. While single-cell transcriptomics has begun to resolve tumor composition, a tumor cell-intrinsic framework linking transcriptional states to clinical outcome and therapeutic targeting is not established. Here, we present a single-cell transcriptomic analysis of pediatric osteosarcoma, integrating 22 samples across 18 patients spanning six diagnostic, six post-treatment, and ten metastatic lesions profiled using complementary sequencing platforms. Using non-negative matrix factorization, we identify recurrent lineage-associated transcriptional programs that define osteoblastic-like, chondroblastic-like, and fibroblastic-like tumor cell states. These programs show overlapping activity across tumor cells, indicating that tumor cell states are not strictly discrete. Strikingly, combined osteoblastic-like and chondroblastic-like program activity is associated with poorer overall survival, a finding validated across two independent bulk RNA-sequencing cohorts. These tumor cell states are further linked to distinct immune microenvironmental compositions. Mapping candidate immunotherapeutic targets at single-cell resolution reveals variable expression across tumor cell states, supporting state-informed strategies for CAR T cell targeting. Together, our findings establish a tumor cell state framework that links osteosarcoma heterogeneity to clinical outcome and provides a basis for patient stratification and the development of state-informed therapeutic strategies in pediatric osteosarcoma.

Cancer Biology↗

bioRxiv2025

Nanoclustering of a plant transcription factor enables strong yet specific DNA binding

Transcription factors (TFs) are traditionally depicted as monomeric, or oligomeric, units that recognize and bind specific DNA sequences to regulate transcription. Emerging evidence suggests that many TFs can undergo liquid phase separation, resulting in condensates that bind DNA through a different mechanism. For the Auxin Response Factors (ARFs), canonical plant TFs, evidence for both scenarios exists. But which of these scenarios is operational in the plant nucleus is unclear. Here, we demonstrate using MpARF2 of Marchantia polymorpha that a third scenario is operational: MpARF2 forms nanoscopic clusters under physiological conditions. Nanoclusters combine DNA-binding features that cannot be accessed by the other two scenarios: high-affinity, switch-like, and sequence-specific. Our results suggest nanoclustering as a mechanism that equips TFs with the DNA-binding properties necessary for transcriptional regulation. TeaserTranscription factor nanoclusters balance the DNA-binding trade-off between weakly binding oligomers and nonspecific condensates.

plant biology↗

bioRxiv2025

Larger hybrid clutch size could drive regional displacement of native Iguana populations across the Lesser Antilles

Native Iguana populations across the Caribbean Lesser Antilles are being replaced by non-native green iguanas (NNGI) once these establish themselves, leading to eventual extinction. Despite this knowledge, and much effort towards NNGI removal and prevention of incursions, the underlying mechanisms of the observed genetic swamping are poorly understood. Previous studies show that larger clutch size is a key reproductive trait of mainland as opposed to insular lizard populations. Higher clutch size in NNGI and their progeny could be a driver in the genetic swamping of insular Iguana populations. We collected data on snout-vent length, tail length, clutch size and genetics opportunistically during an eradication program of hybrid and NNGIs on the island of Saba, home to a native Iguana Iguana population. Data of native and hybrid iguanas from Saba were combined with similar published data from native insular and mainland Iguana populations. Generalized linear modeling revealed that climatic variables could not explain differences in clutch size, in contrast to genetic origins. Our preliminary results show that hybrid iguanas lay significantly more eggs (~40%) than similar-sized native Saba iguanas. Therefore, we suggest that higher hybrid clutch size may be a contributing factor hastening the genetic swamping and declines in native Iguana populations across the Lesser Antilles. Further study is needed to clarify and better understand the drivers of the rapid genetic swamping and loss of Antillean iguana diversity, which should also focus on Iguana delicatissima and utilize genomic approaches to pinpoint genes under selection.

ecology↗

bioRxiv2025

Integrin-TGFβ axis induces partial EMT in basal-like cells to lead collective invasion

Collective invasion is the predominant mode of cancer cell dissemination in breast cancer and represents the initial step of metastatic spread. Basal-like leader cells drive this process by maintaining cell-cell junctions with the follower cells while extending actin-rich protrusions and remodeling the collagen I-rich peritumoral stroma. These features resemble those of individually-invading cells following epithelial-to-mesenchymal transition (EMT). However, how leader cells acquire these traits while preserving cohesion within the collective remains unclear. Here, we identify a collagen I-responsive subset of basal-like cells that coexpress cytoskeletal, extracellular matrix (ECM)-remodeling, and epithelial junction genes. We show that integrin 2 (Itg2) links collagen I engagement to mesenchymal reprogramming by inducing inhibin beta A (INHBA) expression and activating tumor growth factor {beta} (TGF{beta}) signaling. This, in turn, upregulates vimentin while preserving epithelial junction gene expression. In parallel, Itg2 promotes ECM degradation through a TGF{beta}-independent mechanism. This study identifies Itg2-TGF{beta} axis as a key regulator of partial EMT and leader cell function, highlighting it as a potential therapeutic target in aggressive breast cancers.

cell biology↗

bioRxiv2025

Mechanisms of dexamethasone-induced bone toxicity in developing bone: a single-cell perspective

AbstractGlucocorticoids, such as dexamethasone, are essential for treating severe childhood conditions, including cancer, organ transplantation, and inflammatory disorders. However, their long-term use can impair bone development, posing risks to pediatric bone health, which is vital for lifelong skeletal integrity. A mechanistic insight on how glucocorticoids negatively impact bone could improve decision-making in patient care to improve the quality of life for pediatric cancer patients and survivors. In this study, we aimed to elucidate the molecular mechanisms underlying dexamethasone-induced bone toxicity in developing bones using single-cell transcriptomics. We treated skeletally immature C57BL/6JRj mice with dexamethasone for 28 days, and assessed the bone architecture with micro-computed tomography, and characterized bone and bone marrow cells from the femurs using single-cell RNA sequencing. Our findings revealed a marked reduction in osteoblast and chondrocyte cell populations and impaired function of pre-osteoblasts. Additionally, dexamethasone adversely affected B cell subsets, significantly depleting early B cell progenitors while allowing some further developed immature B cells to persist. These cellular changes were accompanied by reduced longitudinal bone growth, compromised bone architecture, and increased bone fragility at the highest doses of dexamethasone. Interestingly, unlike observations in adults, dexamethasone did not enhance osteoclast activity in our model. Overall, our study suggests that the adverse effects of dexamethasone on bone development are primarily due to its impact on osteoblastic, chondroblastic and B cell lineages, disrupting the critical signaling crosstalk between the cells necessary for bone development and hematopoiesis. Layman summaryGlucocorticoids, like dexamethasone, are vital for treating severe childhood illnesses but can harm bone development when used long-term. This study investigated how dexamethasone affects bone health in young mice. Using advanced techniques, we found that dexamethasone reduced key bone-building cells (osteoblasts and chondrocytes) and weakened their function. It also disrupted immune cell development in the bone marrow, especially early B cells. These changes led to weaker, more fragile bones without increasing bone breakdown, unlike in adults. The findings highlight the need to carefully balance treatment benefits and risks for children to protect their bone health and overall well-being.

cancer biology↗

bioRxiv2024

The Mag-Click-Capture-Release Technology for Selective Capture and Release of Hepatocyte-Derived Extracellular Vesicles as Biomarkers for Liver Disease

Chronic liver diseases, such as liver cirrhosis and hepatocellular carcinoma (HCC), present major global health challenges, often diagnosed late. Circulating extracellular vesicles (EVs), which carry disease-specific biomolecular cargo, is emerging as an early diagnostic and prognostic biomarker for several diseases including cancer. However, current EV purification methods including ultracentrifugation and size exclusion chromatography present several limitations. Here, we present the Mag-Click-Capture-Release Technology for selective capture and release of EVs that combines magnetic beads, trans-cyclooctene (TCO) and tetrazine (Tz) click chemistry, immuno(antibody)-based capture and disulfide-driven release of EVs. Importantly, the Mag-Click-Capture-Release Technology is customizable, whereby using specific antibodies conjugated to TCO antibodies, different EV subtypes can be selectively captured and released for further analysis. With our Mag-Click-Capture-Release Technology, we successfully isolated hepatocyte-derived EVs from human serum with good recovery, high specificity and purity when compared with standard ultracentrifugation. Validation in serum samples obtained from cirrhosis and HCC patients with alcohol-associated liver disease evidenced an increasing trend in hepatocyte-EV levels correlating with disease severity, suggesting potential for early diagnosis and prognosis. In conclusion, we present here the Mag-Click-Capture-Release Technology, a customizable and efficient approach for selective isolation of organ-, cell-specific, and disease-relevant EVs from biological samples that can be subsequently released for downstream molecular EV analysis and EV-related functional assays.

bioengineering↗

bioRxiv2023

Patient-Derived Medullary Thyroid Cancer Organoids; a Model for Patient-tailored Drug and PET-Tracer Screening

BackgroundMedullary thyroid carcinoma (MTC) is a neuroendocrine tumor derived from the parafollicular C-cells of the thyroid gland. PET imaging, with various PET tracers, is performed when distant metastatic disease is suspected. After the recognition of progressive disease on imaging, targeted therapy may be initiated to prolong survival. Mutations in the gene encoding the REarranged during Transfection (RET) tyrosine kinase play a key role in the development of MTC. It seems that tyrosine kinase inhibitors (TKIs) inhibit tumor proliferation, but it remains challenging to determine the best patient specific treatment option. Here, we aim to set up an in vitro MTC organoid model to study its potential for patient-tailored drug-screening and uptake of PET tracers. MethodsDispersed cells obtained from surgical MTC biopsies were suspended in Matrigel with defined medium allowing MTC organoid formation. To study putative MTC stem cells, the self-renewal potential of organoids was tested by dissociation to single cells and re-plating. To check MTC origin, MTC-specific gene expression and proteins were characterized by qPCR and immunofluorescent (IF) staining. To investigate cytotoxicity, MTC-organoids (MTOs) were exposed to various TKIs after which hormone (calcitonin and CEA) excretion levels were determined. Lastly, we evaluated cell-specific uptake of clinically used Positron Emission Tomography (PET) tracers. ResultsNine MTC biopsies were processed and cultured as MTOs. Eight MTO lines were used to determine organoid formation efficiency (OFE), which yielded a maximum OFE of 6.3% in passage 1 (p1), 5.9% in p2, and 9.4% in p3, indicating the presence of putative stem cells. IF staining showed expression of MTC-specific markers in both tissue and MTOs showing tissue resemblance. Tumor marker measurements in MTO medium showed MTC-specific production of calcitonin and CEA with changed concentrations after exposure to TKIs. Exposure to PET tracers showed significant uptake in the MTOs. ConclusionMTC organoids can be successfully cultured and resemble the tissue of origin in gene expression, protein expression and functionality. In addition, MTOs can take up PET tracers, and have the potential to be used as a prediction model for TKI treatment in the future.

cancer biology↗

bioRxiv2022

Patient-derived parathyroid organoids as tracer and drug-screening application model

Parathyroid diseases are characterized by dysregulation of calcium homeostasis and alterations in parathyroid hormone (PTH) excretion. The understanding of parathyroid hyperplastic growth and the development of parathyroid-targeted treatment and imaging tracers could benefit from in vitro models. Therefore, we aim to establish stem cell-derived, three-dimensional organoids representing human parathyroid tissue in vitro. Patient-derived hyperplastic parathyroid tissue was dispersed and parathyroid organoids (PTO) were cultured and characterized. PTO-derived cells were shown to exhibit in vitro self-renewal over several passages, indicative of the presence of putative stem cells. Immunofluorescence and RNA-sequencing confirm that PTO phenocopy hyperplastic parathyroid tissue. Exposure of PTO to increasing calcium concentrations and to PTH-lowering drugs resulted in a significantly reduced PTH excretion. Next to this, the PTO showed specific binding of 11C-methionine to the targeted receptor. Additionally, when organoids were incubated with 99mTc-sestamibi, we observed a higher uptake in PTOs from patients with a 99mTc-sestamibi positive scan compared to patients with a negative scan. These data show functionality of PTOs resembling the parathyroid. In conclusion, we present a patient-derived PTO culture, that recapitulates the originating tissue on gene and protein expression and functionality. This PTO model paves the way for future physiology studies and therapeutic target and tracer discovery.

cell biology↗

bioRxiv2021

High resolution species detection: accurate long read eDNA metabarcoding of North Sea fish using Oxford Nanopore sequencing

To monitor the effect of nature restoration projects in North Sea ecosystems, accurate and intensive biodiversity assessments are vital. DNA based techniques and especially environmental DNA (eDNA) metabarcoding is becoming a powerful monitoring tool. However, current approaches are based on genetic target regions <500 nucleotides, which offer limited taxonomic resolution. We developed a method for eDNA metabarcoding, based on nanopore sequencing of a longer amplicon, enabling improved identification of fish species. We designed a universal primer pair targeting a 2kb region of fish mitochondria, and compared it to the commonly used MiFish primer pair that targets only [~]170bp. In sillico and mock community testing showed that the 2kb fragments improved the accurate identification of genetically closely related species. eDNA was amplified, and sequenced using the Oxford Nanopore MinION in combination with the sequence read processing pipeline Decona. Analyzing eDNA from a North Sea aquarium showed that sequences from both primer pairs could be assigned to most species, but both approaches also identified unique species in the aquarium eDNA. Next, both primer pairs were used on multiple eDNA samples from the North Sea. Here, similar location specific fish communities were obtained from both approaches. More species were identified through the MiFish approach in the field samples. Interestingly, this difference was not observed in the aquarium, suggesting that 2kb fragment based metabarcoding potentially detects more recent occurrences of animals. This new method has the potential to improve and expand the molecular toolbox for eDNA based monitoring approaches.

molecular biology↗

bioRxiv2018

Laboratory evolution of a Saccharomyces cerevisiae x S. eubayanus hybrid under simulated lager-brewing conditions: genetic diversity and phenotypic convergence

Saccharomyces pastorianus lager-brewing yeasts are domesticated hybrids of S. cerevisiae x S. eubayanus that display extensive inter-strain chromosome copy number variation and chromosomal recombinations. It is unclear to what extent such genome rearrangements are intrinsic to the domestication of hybrid brewing yeasts and whether they contribute to their industrial performance. Here, an allodiploid laboratory hybrid of S. cerevisiae and S. eubayanus was evolved for up to 418 generations on wort under simulated lager-brewing conditions in six independent sequential batch bioreactors. Characterization of 55 single-cell isolates from the evolved cultures showed large phenotypic diversity and whole-genome sequencing revealed a large array of mutations. Frequent loss of heterozygosity involved diverse, strain-specific chromosomal translocations, which differed from those observed in domesticated, aneuploid S. pastorianus brewing strains. In contrast to the extensive aneuploidy of domesticated S. pastorianus strains, the evolved isolates only showed limited (segmental) aneuploidy. Specific mutations could be linked to calcium-dependent flocculation, loss of maltotriose utilisation and loss of mitochondrial activity, three industrially relevant traits that also occur in domesticated S. pastorianus strains. This study indicates that fast acquisition of extensive aneuploidy is not required for genetic adaptation of S. cerevisiae x S. eubayanus hybrids to brewing environments. In addition, this work demonstrates that, consistent with the diversity of brewing strains for maltotriose utilization, domestication under brewing conditions can result in loss of this industrially relevant trait. These observations have important implications for the design of strategies to improve industrial performance of novel laboratory-made hybrids.

evolutionary biology↗

bioRxiv2018

Healthspan pathway maps in C. elegans and humans highlight transcription, prolifera-tion/biosynthesis and lipids

The molecular basis of aging and of aging-associated diseases is being unraveled at an increasing pace. An extended healthspan, and not merely an extension of lifespan, has become the aim of medical practice. However, a precise definition of health and healthspan is not straightforward, and the causal molecular basis of health \"per se\" is largely unknown. Here, we define health based on the absence of diseases and dysfunctions. Based on an extensive review of the literature, in particular for humans and C. elegans, we compile a list of features of health and of the genes associated with them. Clusters of these genes based on molecular interaction data give rise to maps of healthspan pathways for humans, featuring the themes transcription initiation, proliferation and cholesterol/lipid processing, and for C. elegans, featuring the themes immune response, mitochondrion and biosynthesis based on genetic and compound intervention data, and lipids, biosynthesis and transcription based on WormBase compound intervention data. Overlaying healthspan-related gene expression data (describing effects of metabolic intervention associated with improvements in health) onto the aforementioned healthspan pathway maps, we observe the downregulation of Notch signalling in humans and of proliferation/cell-cycle in C. elegans. The former reflects the proinflammatory role of the Notch pathway. We identify transcription, proliferation/biosynthesis and lipids as a common theme on the annotation level, and proliferation-related kinases on the gene/protein level. Our literature-based data corpus, including visualization, is available as a reference for future investigations, at http://www.h2020awe.eu/index.php/pathways/.

bioinformatics↗

bioRxiv2018

A synthetic, three-dimensional bone marrow hydrogel

Three-dimensional (3D) synthetic hydrogels have recently emerged as desirable in vitro cell culture platforms capable of representing the extracellular geometry, elasticity, and water content of tissue in a tunable fashion. However, they are critically limited in their biological functionality. Hydrogels are typically decorated with a scant 1-3 peptide moieties to direct cell behavior, which vastly underrepresents the proteins found in the extracellular matrix (ECM) of real tissues. Further, peptides chosen are ubiquitous in ECM, and are not derived from specific proteins. We developed an approach to incorporate the protein complexity of specific tissues into the design of biomaterials, and created a hydrogel with the elasticity of marrow, and 20 marrow-specific cell-instructive peptides. Compared to generic PEG hydrogels, our marrow-inspired hydrogel improves stem cell differentiation and proliferation. We propose this tissue-centric approach as the next generation of 3D hydrogel design for applications in tissue engineering.

bioengineering↗