Biology subjects

Maciag, G.

Publications and source records attributed to Maciag, G..

3 recordsLinked to original sources

bioRxiv2024

JAK/STAT signaling promotes the emergence of unique cell states in ulcerative colitis

The intestinal epithelium forms a barrier to the lumen and ensures uptake of vital nutrients. During inflammatory diseases, such as ulcerative colitis (UC), this barrier is compromised. Here, we perform single-cell RNA sequencing (scRNA-seq) of epithelial cells and outline patterns of cell fate decisions in healthy individuals and patients with UC. We demonstrate that lineage biased progenitors are major sources of normal tissue replenishment, and that patterns of cell behavior are profoundly altered in UC. We furthermore identify unique regenerative cell states linked to JAK/STAT activation extending into the non-inflamed areas of the colon. In organoid models, this can be mimicked by cytokine mediated activation of JAK/STAT leading to the emergence of cell populations with regenerative potential. These findings have profound implications for our understanding of tissue regeneration and illustrates how cytokine signaling influences cell fate decisions. This suggests widespread consequences in patients with chronic ulcerative conditions.

cell biology↗

bioRxiv2023

An integrated transcriptomic cell atlas of human endoderm-derived organoids

Human stem cells can generate complex, multicellular epithelial tissues of endodermal origin in vitro that recapitulate aspects of developing and adult human physiology. These tissues, also called organoids, can be derived from pluripotent stem cells or tissue-resident fetal and adult stem cells. However, it has remained difficult to understand the precision and accuracy of organoid cell states through comparison with primary counterparts, and to comprehensively assess the similarity and differences between organoid protocols. Advances in computational single-cell biology now allow the integration of datasets with high technical variability. Here, we integrate single-cell transcriptomes from 218 samples covering organoids of diverse endoderm-derived tissues including lung, pancreas, intestine, liver, biliary system, stomach, and prostate to establish an initial version of a human endoderm organoid cell atlas (HEOCA). The integration includes nearly one million cells across diverse conditions, data sources and protocols. We align and compare cell types and states between organoid models, and harmonize cell type annotations by mapping the atlas to primary tissue counterparts. To demonstrate utility of the atlas, we focus on intestine and lung, and clarify ontogenic cell states that can be modeled in vitro. We further provide examples of mapping novel data from new organoid protocols to expand the atlas, and showcase how integrating organoid models of disease into the HEOCA identifies altered cell proportions and states between healthy and disease conditions. The atlas makes diverse datasets centrally available, and will be valuable to assess organoid fidelity, characterize perturbed and diseased states, and streamline protocol development.

cell biology↗

bioRxiv2023

Transcriptional and epigenomic profiling identifies YAP signaling as a key regulator of intestinal epithelium maturation

During intestinal organogenesis, equipotent epithelial progenitors mature into phenotypically distinct stem cells that are responsible for life-long maintenance of the tissue. While the morphological changes associated with the transition are well-characterized, the molecular mechanisms underpinning the maturation process are not fully understood. Here, we leverage intestinal organoid cultures to profile transcriptional, chromatin accessibility, DNA methylation and 3D chromatin conformation landscapes defining fetal and adult epithelial cells. We observed prominent differences in gene expression and enhancer activity, accompanied by changes in 3D organization and local changes in DNA accessibility and methylation, between the two cellular states. Using integrative analyses, we identified sustained YAP transcriptional activity as a major gatekeeper of the immature fetal state. We found the YAP-associated transcriptional network to be regulated at various levels of chromatin organization, and likely to be coordinated by changes in extracellular matrix composition. Altogether, our work highlights the value of unbiased profiling of regulatory landscapes for the identification of key mechanisms underlying tissue maturation.

developmental biology↗