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Paraskevopoulou, M. D.

Publications and source records attributed to Paraskevopoulou, M. D..

3 recordsLinked to original sources

A Micro-engineered Human Colon Intestine-Chip Platform to Study Leaky Barrier

The intestinal epithelial barrier supports the symbiotic relationship between the microbiota colonizing the intestinal epithelium and the host immune system to maintain homeostasis. Leaky barrier is increasingly recognized as part of the pathogenesis of a number of chronic conditions in addition to inflammatory and infectious diseases. As our understanding on the regulation of the barrier remains limited, effective therapeutic targeting for the compromised barrier is still an unmet need. Here we combined advancements on the organoids and Organ-on-Chip technologies to establish a micro-engineered Colon Intestine-Chip for studying development and regulation of the human intestinal barrier. Our data demonstrate the significance of the endothelium in co-culture with the epithelial cells within a tissue-relevant microenvironment for the establishment of a tight epithelial barrier of polarized cells. Pathway analysis of the RNA sequencing (RNA-Seq), revealed significant upregulation of mechanisms relevant to the maturation of the intestinal epithelium in organoid-derived epithelial cells in co-culture with endothelium as compared to organoids maintained in suspension. We provide evidence that the Colon Intestine-Chip platform responds to interferon gamma (IFN{gamma}), a prototype cytokine utilized to model inflammation-induced barrier disruption, by induction of apoptosis and reorganization of the apical junctional complexes as shown with other systems. We also describe the mechanism of action of interleukin 22 (IL-22) on mature, organoid-derived intestinal epithelial cells that is consistent with barrier disruption. Overall we propose the Colon Intestine-Chip as a promising human organoid-derived platform to decipher mechanisms driving the development of leaky gut in patients and enable their translation for this unmet medical need.

bioengineering

IWS1 phosphorylation promotes cell proliferation and predicts poor prognosis in EGFR mutant lung adenocarcinoma patients, through the cell cycle-regulated U2AF2 RNA splicing.

The authors have withdrawn their manuscript. While attempting to reproduce the data on the alternative splicing of exon 2 of U2AF2, they observed that the proposed splicing mechanism could not give rise to a functional U2AF2 protein. In addition, they observed evidence of manipulation in the electropherogram of the splicing junction between exons 1 and 3 and in the primary data on which this electropherogram was based, which were deposited in Mendeley by the first author. These observations raise questions on the integrity of the reported results. In light of this information, the authors have no confidence in the key findings of the paper, and therefore, do not wish it to be cited. If you have any questions, please contact the corresponding author.

cancer biology

The inhibition of KDM2B promotes the differentiation of basal-like breast cancer cells via the posttranslational destabilization of SLUG.

KDM2B is a JmjC domain H3K36me2/H3K36me1 demethylase, which immortalizes cells in culture and contributes to the biology of both embryonic and adult stem cells, including cancer stem cells. Here we show that the silencing of KDM2B activates a tyrosine kinase receptor-dependent paracrine mechanism, which results in the downregulation of SNAI2 (SLUG), SNAI1 (SNAIL) and SOX9, which also contribute to the biology of stem and progenitor cells. The downregulation of these molecules is posttranscriptional and in the case of SNAI2-encoded SLUG, it is due to calpain-dependent proteolytic degradation. SLUG abundance in normally growing cells is under the homeostatic control of GSK3, which phosphorylates SLUG and tags it for proteasomal degradation. The paracrine mechanism activated by KDM2B depletion, activates FGFR1 and EGFR family members, and blocks the homeostatic SLUG degradation by inactivating GSK3. This, however, sensitizes SLUG to classical calpains, which are also activated in KDM2B-depleted cells via Ca2+ influx and calpastatin downregulation. The switch in SLUG degradation pathways, results in the rapid degradation of SLUG and the differentiation of breast cancer stem cells, revealing an unexpected mechanism of stem cell regulation by a lysine demethylase. HIGHLIGHTSO_LIGSK3 phosphorylates SLUG and promotes its homeostatic proteasomal degradation C_LIO_LIKDM2B depletion results in GSK3 inactivation, Ca2+ upregulation and calpain activation. C_LIO_LIDownregulation of SLUG phosphorylation by GSK3, sensitizes SLUG to calpain activation. C_LIO_LIGSK3 inactivation and Ca2+ upregulation are due to an RTK-dependent paracrine mechanism C_LI O_FIG O_LINKSMALLFIG WIDTH=199 HEIGHT=200 SRC="FIGDIR/small/109819v2_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@1cee15corg.highwire.dtl.DTLVardef@12d757corg.highwire.dtl.DTLVardef@17c2dd4org.highwire.dtl.DTLVardef@1a4dcef_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology