Biology subjects

Poisel, E.

Publications and source records attributed to Poisel, E..

3 recordsLinked to original sources

bioRxiv2024

Active repression of cell fate plasticity by PROX1 safeguards hepatocyte identity and prevents liver tumourigenesis

Cell fate plasticity enables development, yet unlocked plasticity is a cancer hallmark. Regulating cell identity requires gene activation and repression. While master regulators induce lineage-specific genes to restrict plasticity, it remains unclear whether unwanted plasticity is actively suppressed by lineage-specific repressors. Here, we computationally predict so-called safeguard repressors for 18 cell types that block phenotypic plasticity lifelong. We validated hepatocyte-specific candidates using reprogramming, revealing that Prospero homeobox protein 1 (PROX1) enhanced hepatocyte identity by direct repression of alternate fate master regulators. In mice, Prox1 was required for efficient hepatocyte regeneration after injury and acted as a tumour suppressor in multiple liver cancer models. In line with patient data, Prox1 depletion caused hepatocyte fate loss in vivo, and promoted transition of hepatocellular carcinoma to cholangiocarcinoma, conversely, overexpression promoted cholangiocarcinoma to hepatocellular carcinoma transdifferentiation. Our findings provide mechanistic evidence for PROX1 as a hepatocyte-specific safeguard and support a model where individual cell type-specific repressors actively suppress plasticity throughout life to safeguard lineage choice and prevent disease.

cancer biology↗

bioRxiv2022

Capturing the pathomechanisms of different disease severities in a human cerebral organoid model of LIS1-lissencephaly

Lissencephaly is a malformation of cortical development (MCD) characterized by reduced to absent gyri and a disorganized cortex, leading to severe neurological consequences in affected individuals, including epilepsy, intellectual disability, and reduced life expectancy. Treatments are purely symptomatic, and patients often remain refractory to them. Heterozygous mutations in the LIS1 gene, encoding a regulator of the microtubule motor dynein, cause LIS1-lissencephaly. For unknown reasons, LIS1-lissencephaly patients show marked differences in disease severity despite each carrying a heterozygous LIS1 mutation. We leveraged forebrain-type organoids from patients diagnosed with mild, moderate, or severe LIS1-lissencephaly to investigate, in a cytoarchitecture and multi-omics approach, disease and severity grade associated phenotypes, mechanisms, and rescue approaches. We identified alterations of the cytoarchitecture, progenitor cell homeostasis, and neurogenesis often with a severity-dependent gradient. Identified disease-linked molecular mechanisms were microtubule destabilization, WNT-signaling, protein metabolism, and perturbed cadherin- and unfolded protein-binding. Some mechanisms exhibited a severity-dependent gradient or were specific to a severe grade. We present strategies to reverse phenotypic changes in LIS1-patient organoids and identify mTOR pathway inhibitors in in silico drug repurposing analysis as potential novel therapeutic strategy. By probing the top hit drug, the mTOR inhibitor everolimus, we could indeed rescue severity-dependent phenotypic changes in LIS1-patient organoids. This study demonstrates that organoid-based modeling is sensitive in recapitulating disease severity, which presents an important step in patient stratification, and allows the development of novel personalized rescue strategies with therapeutic potential.

neuroscience↗

bioRxiv2021

Towards 3D-Bioprinting of an Endocrine Pancreas: A Building-Block Concept for Bioartificial Insulin-Secreting Tissue

Background & Aims3D-Bioprinting of an endocrine pancreas is a promising future curative treatment for selected patients with insulin secretion deficiency. In this study we present an end-to-end integrative, scalable concept extending from the molecular to the macroscopic level. MethodsA hybrid scaffold device was manufactured by 3D-(bio)printing. INS-1 cells with/without endothelial cells were bioprinted in gelatin methacrylate blend hydrogel. Polycaprolactone was 3D-printed and heparin-functionalized as structural scaffold component. In vitro evaluation was performed by viability and growth assays, total mRNA sequencing, and glucose-stimulated insulin secretion. In vivo, xenotransplantation to fertilized chicken eggs was used to investigate vascularization and function, and finite element analysis modeling served to detect boundary conditions and applicability for human islets of Langerhans. ResultsInsulin-secreting pseudoislets were formed and resulted in a viable and proliferative experimental model. Transcriptomics revealed upregulation of proliferative and {beta}-cell-specific signaling cascades, downregulation of apoptotic pathways, and overexpression of extracellular matrix proteins and VEGF induced by pseudoislet formation and 3D culture. Co-culture with human endothelial cells created a natural cellular niche resulting in enhanced insulin response after glucose stimulation. Survival and function of the pseudoislets after explantation and extensive scaffold vascularization of both the hydrogel and heparinized polycaprolactone components were demonstrated in ovo. Computer simulations of oxygen, glucose, and insulin flows were used to evaluate scaffold architectures and Langerhans islets at a future transplantation site along neurovascular structures. ConclusionA defined end-to-end process for multidisciplinary bioconvergence research on a bioartificial endocrine pancreas was developed. A modular, patient-specific device architecture is proposed for future research studies.

bioengineering↗