Biology subjects

Seidler, S.

Publications and source records attributed to Seidler, S..

3 recordsLinked to original sources

bioRxiv2026

Reversible Opto-Chemical activation of KRASG12V signaling with near single-cell precision

KRAS mutations drive some of the most lethal carcinomas, and genomic and inducible systems have established many of the cellular and tissue-level consequences. However, these approaches operate at the level of oncogene expression, allowing for cellular adaptation that masks the individual role of KRAS oncoprotein signaling. Here, we developed a reversible Opto-Chemical system to activate KRAS signaling by chemically translocating a cytosolic mutant KRASG12V G-domain to the plasma membrane upon light or small-molecule input. In MDCK cells, the G-domain plasma membrane recruitment activated downstream signaling and reduced collective migration. In mouse small Intestinal Organoids, G-domain recruitment promoted increased crypt size and number under Epidermal Growth Factor-deprived conditions. We further showed that the increased number of crypts depended on continuous KRASG12V signaling. Finally, under the same deprived conditions, localized activation in just one budding crypt promoted crypt formation compared to controls. This system decouples oncoprotein activity from oncogene expression, allowing to investigate the KRAS signaling contribution to early epithelial transformation.

Systems Biology↗

bioRxiv2026

Oncomimetic β-catenin activity onset, duration and region defines aberrant intestinal development

In early intestinal carcinogenesis, adenoma formation is commonly initiated by loss-of-function mutations in a tumor suppressor that lead to oncoprotein gain-of-function, like in the tumor suppressor-oncoprotein pair APC-{beta}-catenin. Small intestinal organoids provide an in vitro system to study consequences of such mutations on tissue organization. However, conventional genetic manipulations do not allow precise control over the onset and duration of oncoprotein activity to study their influence on tissue transformation. Furthermore, homogenous tissues of clonal genetic models do not readily capture cellular interaction among mutated and neighboring wildtype tissue during early transformation. To mimic oncogenic activation of {beta}-catenin, we established a chemical-(opto)genetic approach to gain bio-orthogonal acute, spatial and temporal control over {beta}-catenin oncoprotein stability and relate oncoprotein levels to morphological development of mouse small intestinal organoids. We identified aberrant phenotypes that result from bio-orthogonally induced oncoprotein activity but persist even after oncoprotein depletion. Furthermore, local activation of oncomimetic {beta}-catenin activity within the stem cell niche leads to aberrant differentiation during homeorhesis and homeostasis, recapitulating early events of tissue transformation.

cancer biology↗

bioRxiv2026

Proliferation and differentiation in intestinal organoids as a balance of ligand-modulated the EGFR trafficking

Epidermal Growth factor (EGF) signaling is associated with (oncogenic) proliferation. Conversely, EGF-family ligands are able to trigger a differentiation program in cultured cells, an effect attributed to ligand affinity and EGFR phosphorylation. How EGF/EGFR driven proliferation-differentiation dynamics underlie tissue self-renewal has not been addressed. We show that culturing mouse small intestinal organoids (mSIOs) without EGF enhanced EGFR expression and base phosphorylation while maintaining a balanced development of proliferative crypts and differentiated villi. Addition of EGF or EREG triggers receptor endocytosis, reducing cell-surface and expression levels. While EGF promoted crypt proliferation, EREG promoted both proliferation and villus differentiation compared to untreated controls. Removal or re-introduction of EGF or EREG proved sufficient to induce development comparable to constant presence of ligands over 96h. Sub-saturating concentrations of EGF led to increased villus differentiation, resembling EREG treatments, suggesting that control over EGFR endocytic cycle ultimately regulates the balance of proliferation and differentiation in mSIOs SummaryExpression and signaling competency at the plasma membrane of EGFR drives crypt proliferation vs villus differentiation by medium ligand-composition, aiding mouse intestinal organoids self-renewal and regeneration.

developmental biology↗