Biology subjects

Maertens, A.

Publications and source records attributed to Maertens, A..

5 recordsLinked to original sources

bioRxiv2025

Genetic Background and Sex Modulate Androgen Responses in Human Brain Microphysiological System

Sex steroids shape human brain development, yet the cellular and molecular consequences of androgen addition need further exploration. Here, we used a human neural organoid model - brain microphysiological system (bMPS), derived from nine induced pluripotent stem cell (iPSC) lines to model the impact of dihydrotestosterone (DHT), a potent non-aromatizable androgen. All lines differentiated reproducibly into electrically active, neuron-glia-oligodendrocyte organoids expressing robust androgen-signaling components. DHT was bioavailable, elicited nuclear androgen receptor (AR) translocation and increased organoid size in most cell lines, consistent with androgen-responsive mTOR and metabolic pathway activation. Bulk RNA-seq across nine lines revealed that transcriptional responses varied across donor backgrounds, but DHT-responsive genes converged on mitochondrial energetics, lysosomal function, glycoprotein processing, apoptosis, and mTOR signaling. Cell-type expression profiling showed an androgen-driven shift primarily in male lines toward astrocytic profiles with reductions in oligodendrocyte, oligodendrocyte progenitor (OPC), excitatory, and inhibitory neuronal signatures, supported by immunohistochemistry and AR enrichment in astrocytes and OPCs. DHT also altered neurodevelopmental pathways, increasing variation in synaptic pruning and decreasing variation in neuronal migration, with autism spectrum disorder (ASD) diagnosis and seizure status of donors moderating these effects more strongly than sex. Baseline transcriptional differences distinguished iPSC lines which responded more strongly to DHT from weak responders: responders displayed enhanced synaptic maturity and reduced ECM gene expression. Using isogenic XX/XY lines, we found that differences in sex-chromosome expression exceeded DHT-induced changes and that DHT decreased expression of inhibitory neuron genes in males and increased it in females. Finally, DHT induced extensive DNA methylation changes, targeting HOX genes, patterning, and synaptic genes. Collectively, these findings reveal that androgen signaling shapes transcription, cell populations, and epigenetic landscapes in a genetic background-dependent manner. This work contributes to understanding how androgens influence human brain development and highlights how in vitro models can contribute to representing inter-individual variability in neurodevelopment and neurodevelopmental disorders.

neuroscience↗

bioRxiv2025

Cross-linking mass spectrometry for structure analysis of the intrinsically disordered Tau and phosphorylated Tau protein

We present a novel method for analyzing the folding of intrinsically disordered proteins (IDPs), such as Tau and phosphorylated Tau (pTau), in solution. Using cross-linking mass spectrometry combined with a new downstream analysis framework, we construct weighted interaction networks from cross-link-derived residue pairs without relying on predefined secondary structure assumptions. Structural differences between protein conformations are quantified by comparing the organization of loop structures within their cross-link networks. Validation with bovine serum albumin (BSA) in native and denatured states shows that at least 500 cross-links--requiring 5-10 replicate measurements--are needed for reliable detection of structural divergence. Leave-one-out analysis confirms that structural transitions are global, highlighting the importance of comprehensive cross-link datasets. The coverage of unique cross-links was evaluated using accumulation curves from randomized permutations. Saturation levels were found to be 9.7%, 5.0%, and 6.2% of the total 528 and 10,731 possible cross-links after 30, 84, and 62 technical replicates, respectively, for myoglobin, native BSA, and denatured BSA. For Tau and pTau, coverage reached 10.8% and 5.5% of the upper limit (8,256). Finally, applying our structural analysis to Tau and pTau during arachidonic acid-induced aggregation revealed distinct patterns of structural evolution between the two proteins.

biochemistry↗

bioRxiv2024

Prenatal Arsenic Exposure and Gene Expression in Fetal Liver, Heart, Lung, and Placenta

Prenatal arsenic exposure has been linked to a myriad of negative health effects. There is relatively little insight into the mechanisms and signaling alterations across different fetal organs that drive long-term immune-related issues following prenatal arsenic exposure. Therefore, the effects of this exposure window on gene expression in the liver, placenta, heart, and lung of gestation day (GD) 18 C57BL/6 mouse fetuses were investigated. From two weeks prior to mating until tissue collection at GD18, mice were exposed to 0 or 100 ppb sodium (meta) arsenite in drinking water. Genes of interest were analyzed by RT-qPCR, complemented with untargeted Agilent 44K microarray analysis. Data cleanup and analysis was performed in RStudio. Differentially expressed mRNAs were queried in the String Database and using Cytoscape to create interaction networks and identify significantly enriched biological pathways. A total of 251, 165, 158, and 41 genes were significantly altered in the liver, placenta, heart, and lung, respectively, when treated samples were compared to controls. Many altered pathways were immune-related, supporting prior research. Most notably, gene expression of Gbp3, a key player in the cellular response to interferon gamma, was found to be reduced in placentas of female fetuses exposed to arsenic compared to controls (p=0.0762). ImpactThis is the first study comparing alterations in gene expression across multiple organs following prenatal exposure to environmentally relevant levels of arsenic. These findings, elucidating the multi-organ impact of prenatal arsenic exposure on predominantly immune-related pathways, further our mechanistic understanding of the long-term health effects observed in early-life arsenic-exposed populations.

pharmacology and toxicology↗

bioRxiv2023

Transcriptomic Effects of Low-Dose Inorganic Arsenic Exposure on Murine Bone Marrow-Derived Macrophages.

Both tissue-resident macrophages and monocytes recruited from the bone marrow that transform into tissue-resident cells play critical roles in mediating homeostasis as well as in the pathology of inflammatory diseases. Inorganic arsenic (iAs) is the most common drinking water contaminant worldwide and represents a major public health concern. Several diseases that macrophages have implicated involvement in are caused by iAs exposure, including cardiovascular disease, cancer, and increased risk of infectious disease. Therefore, understanding the effects of iAs exposure on macrophages can help us better grasp the full range of arsenic immunotoxicity and better design therapeutic targets for iAs-induced diseases particularly in exposed populations. In this study, we analyzed the transcriptome of low dose iAs-exposed male and female murine bone marrow-derived macrophages (BMDMs) with either M0, M1, or M2 stimulation. We identified differentially expressed genes by iAs in a sex- and stimulation-dependent manner and used bioinformatics tools to predict protein-protein interactions, transcriptional regulatory networks, and associated biological processes. Overall, our data suggest that M1-stimulated, especially female-derived, BMDMs are most susceptible to iAs exposure. Most notably, we observed significant downregulation of major proinflammatory transcription factors, like IRF8, and its downstream targets, as well as genes encoding proteins involved in pattern recognition and antigen presentation, such as TLR7, TLR8, and H2-D1, potentially providing causal insight regarding arsenics role in perturbing immune responses to infectious diseases. We also observed significant downregulation of genes involved in processes crucial to coordinating a proinflammatory response including leukocyte migration, differentiation, and cytokine and chemokine production and response. Finally, we discovered that 24 X-linked genes were dysregulated in iAs-exposed female stimulation groups compared to only 3 across the iAs-exposed male stimulation groups. These findings elucidate the potential mechanisms underlying the sex-differential iAs-associated immune-related disease risk.

pharmacology and toxicology↗

bioRxiv2021

Personalized Perturbation Profiles Reveal Concordance between Autism Blood Transcriptome Datasets

The complex heterogeneity of Autism Spectrum Disorder (ASD) has made quantifying disease specific molecular changes a challenge. Blood based transcriptomic assays have been performed to isolate these molecular changes and provide biomarkers to aid in ASD diagnoses, etiological understanding, and potential treatment1-6. However, establishing concordance amongst these studies is made difficult in part by the variation in methods used to call putative biomarkers. Here we use personal perturbation profiles to establish concordance amongst these datasets and reveal a pool of 1,189 commonly perturbed genes and new insights into poorly characterized genes that are perturbed in ASD subjects. We find the resultant perturbed gene pools to include the following unnamed genes: C18orf25, C15orf39, C1orf109, C1orf43, C19orf12, C6orf106, C3orf58, C19orf53, C17orf80, C4orf33, C21orf2, C10orf2, C1orf162, C10orf25 and C10orf90. Investigation into these genes using differential correlation analysis and the text mining tool Chilibot reveal interesting connections to DNA damage, ubiquitination, R-loops, autophagy, and mitochondrial damage. Our results support evidence that these cellular events are relevant to ASD molecular mechanisms. The personalized perturbation profile analysis scheme, as described in this work, offers a promising way to establish concordance between seemingly discordant expression datasets and expose the relevance of new genes in disease.

bioinformatics↗