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In order to circumvent the limited access and donor variability of human primary alveolar cells, directed differentiation of human pluripotent stem cells (hiPSCs) into alveolar-like cells, provides a promising tool for respiratory disease modeling and drug discovery assays. In this work, a unique, miniaturized 96-Transwell microplate system is described where hiPSC-derived alveolar-like cells were cultured at an air–liquid interface (ALI). To this end, hiPSCs were differentiated into lung epithelial progenitor cells (LPCs) and subsequently matured into a functional alveolar type 2 (AT2)-like epithelium with monolayer-like morphology. AT2-like cells cultured at the physiological ALI conditions displayed characteristics of AT2 cells with classical alveolar surfactant protein expressions and lamellar-body like structures. The integrity of the epithelial barriers between the AT2-like cells was confirmed by applying a custom-made device for 96-parallelized transepithelial electric resistance (TEER) measurements. In order to generate an IPF disease-like phenotype in vitro, the functional AT2-like cells were stimulated with cytokines and growth factors present in the alveolar tissue of IPF patients. The cytokines stimulated the secretion of pro-fibrotic biomarker proteins both on the mRNA (messenger ribonucleic acid) and protein level. Thus, the hiPSC-derived and cellular model system enables the recapitulation of certain IPF hallmarks, while paving the route towards a miniaturized medium throughput approach of pharmaceutical drug discovery.

Unveiling the molecular mechanisms of tissue remodelling following injury is imperative to elucidate its regenerative capacity and aberrant repair in disease. Using different omics approaches, we identified enhancer of zester homolog 2 (EZH2) as a key regulator of fibrosis in injured lung epithelium. Epithelial injury drives an enrichment of nuclear transforming growth factor‐β‐activated kinase 1 (TAK1) that mediates EZH2 phosphorylation to facilitate its liberation from polycomb repressive complex 2 (PRC2). This process results in the establishment of a transcriptional complex of EZH2, RNA‐polymerase II (POL2) and nuclear actin, which orchestrates aberrant epithelial repair programmes. The liberation of EZH2 from PRC2 is accompanied by an EZH2‐EZH1 switch to preserve H3K27me3 deposition at non‐target genes. Loss of epithelial TAK1, EZH2 or blocking nuclear actin influx attenuates the fibrotic cascade and restores respiratory homeostasis. Accordingly, EZH2 inhibition significantly improves outcomes in a pulmonary fibrosis mouse model. Our results reveal an important non‐canonical function of EZH2, paving the way for new therapeutic interventions in fibrotic lung diseases., TAK1‐mediated phosphorylation of EZH2 regulates fibrotic epithelial remodelling after injury. EZH2 inhibition improves outcomes in a pulmonary fibrosis model, suggesting that targeting the TAK1‐EZH2 axis has therapeutic efficacy for idiopathic pulmonary fibrosis (IPF).

To restore organ homeostasis, a myriad of cell types need to activate rapid and transient programs to adjust cell fate decisions and elicit a collective behaviour. Characterisation of such programs are imperative to elucidate an organ’s regenerative capacity and its aberrant repair in disease. By modelling epithelial-mesenchymal crosstalk, we provide direct evidence for transforming growth factor β1 (TGFβ1)-damaged epithelium initiating a bi-directional fibrotic cascade with the mesenchyme. Strikingly, TGFβ1-damaged epithelia facilitates the release of Enhancer of Zester Homolog 2 (EZH2) from Polycomb Repressive Complex 2 (PRC2) to establish a novel fibrotic transcriptional complex of EZH2, RNA-polymerase II (POL2) and nuclear actin. Perturbing this complex by disrupting epithelial EZH2 or actomyosin remodelling abrogates the fibrotic crosstalk. The liberation of EZH2 from PRC2 is accompanied by an EZH2-EZH1 switch to preserve global H3K27me3 occupancy. Our results reveal an important non-canonical function of EZH2, paving the way for therapeutic interventions in fibrotic disease.

In order to overcome the challenges associated with a limited number of airway epithelial cells that can be obtained from clinical sampling and their restrained capacity to divide ex vivo, miniaturization of respiratory drug discovery assays is of pivotal importance. Thus, a 96-well microplate system was developed where primary human small airway epithelial (hSAE) cells were cultured at an air–liquid interface (ALI). After four weeks of ALI culture, a pseudostratified epithelium containing basal, club, goblet and ciliated cells was produced. The 96-well ALI cultures displayed a cellular composition, ciliary beating frequency, and intercellular tight junctions similar to 24-well conditions. A novel custom-made device for 96-parallelized transepithelial electric resistance (TEER) measurements, together with dextran permeability measurements, confirmed that the 96-well culture developed a tight barrier function during ALI differentiation. 96-well hSAE cultures were responsive to transforming growth factor β1 (TGF-β1) and tumor necrosis factor α (TNF-α) in a concentration dependent manner. Thus, the miniaturized cellular model system enables the recapitulation of a physiologically responsive, differentiated small airway epithelium, and a robotic integration provides a medium throughput approach towards pharmaceutical drug discovery, for instance, in respect of fibrotic distal airway/lung diseases.

Two-step role for mutant TERT promoters Telomeres preserve genomic stability by preventing chromosomal fusions. The recent discovery that human tumors harbor mutations in the promoter region of the telomerase gene ( TERT ) produced a flurry of research aimed at elucidating the role of these mutations in cancer development. Chiba et al. present data that reconcile many of the conflicting results reported to date (see the Perspective by Shay). In human melanoma samples and a fibroblast model, TERT promoter mutations acted in two steps. First, the mutations allowed cells to proliferate with short telomeres. This fueled genomic instability and up-regulation of telomerase expression, leading to uncontrolled cell proliferation. Science , this issue p. 1416 ; see also p. 1358

While the pathophysiology remains unclear, growing evidence suggests that a pro-fibrotic milieu and dysfunctional epithelial repair likely play key roles in IPF. An emergence of airway epithelial like cells of unknown origin is frequently observed in distorted alveolar regions in IFP. We aimed to investigate if a pro-fibrotic environment could drive aberrant trans-differentiation of alveolar epithelial progenitors towards airway epithelial like cells. We used an iPSC-derived air-liquid interface model of directed ATII cell differentiation and treated the cells with an IPF-relevant cocktail (IPF-RC), composed of cytokines previously described to be upregulated in IPF patient lungs. Characterization by qRT-PCR, RNAseq, IF and TEM confirmed the ATII-like phenotype of the cultures. IPF-RC stimulation during differentiation resulted in significantly reduced expression of SFTPC and increased airway related transcript expression, including KRT5, SCGB1A1, MUC5B and BPIFB1. In comparison, primary small airway basal cells differentiated in the presence of IPF-RC displayed an upregulated expression of KRT5, BPIFB1 and MUC5AC (but not MUC5B), and a downregulation in SCGB1A1. We have thus shown that an IPF-related cytokine environment has the potential to drive aberrant alveolar epithelial progenitor differentiation towards an airway epithelial like expression signature, resembling that observed in IPF lungs, that could be distinguished from primary small airway basal cells differentiated in the presence of the same cytokines. These findings indicate that aberrant alveolar epithelial stem cell differentiation could play a role in IPF-associated bronchiolisation.

In drug discovery, there is an increasing demand for more physiological in vitro models that recapitulate the disease situation in patients. Human induced pluripotent stem (hiPS) cell-derived model cells could serve this purpose. To date, several directed differentiation approaches have been described to generate definitive endoderm (DE) from hiPS cells, but protocols suitable for drug development and high-throughput screening (HTS) have not been reported yet. In this work, a large-scale expansion of hiPS cells for high-throughput adaption is presented and an optimized stepwise differentiation of hiPS cells into DE cells is described. The produced DE cells were demonstrated to express classical DE markers on the gene expression and protein level. The here described DE cells are multipotent progenitors and act as starting points for a broad spectrum of endodermal model cells in HTS and other areas of drug discovery.

// Patrick Wolter 1, * , Steffen Hanselmann 1, * , Grit Pattschull 1 , Eva Schruf 1 , Stefan Gaubatz 1 1 Theodor Boveri Institute, Biocenter, University of Wuerzburg and Comprehensive Cancer Center Mainfranken, University of Wuerzburg, University of Wuerzburg, Wuerzburg, Germany * These authors contributed equally to this work Correspondence to: Stefan Gaubatz, email: stefan.gaubatz@biozentrum.uni-wuerzburg.de Keywords: B-MYB, FOXM1, MuvB, DREAM, kinesin Received: October 04, 2016 Accepted: December 26, 2016 Published: January 03, 2017 ABSTRACT The MuvB multiprotein complex, together with B-MYB and FOXM1 (MMB-FOXM1), plays an essential role in cell cycle progression by regulating the transcription of genes required for mitosis and cytokinesis. In many tumors, B-MYB and FOXM1 are overexpressed as part of the proliferation signature. However, the transcriptional targets that are important for oncogenesis have not been identified. Given that mitotic kinesins are highly expressed in cancer cells and that selected kinesins have been reported as target genes of MMB-FOXM1, we sought to determine which mitotic kinesins are directly regulated by MMB-FOXM1. We demonstrate that six mitotic kinesins and two microtubule-associated non-motor proteins (MAPs) CEP55 and PRC1 are direct transcriptional targets of MuvB, B-MYB and FOXM1 in breast cancer cells. Suppression of KIF23 and PRC1 strongly suppressed proliferation of MDA-MB-231 cells. The set of MMB-FOXM1 regulated kinesins genes and 4 additional kinesins which we referred to as the mitotic kinesin signature (MKS) is linked to poor outcome in breast cancer patients. Thus, mitotic kinesins could be used as prognostic biomarker and could be potential therapeutic targets for the treatment of breast cancer.