Mitigating Ischemic Injury of Stem Cell-Derived Insulin-Producing Cells after Transplant.

The advent of large-scale in vitro differentiation of human stem cell-derived insulin-producing cells (SCIPC) has brought us closer to treating diabetes using stem cell technology. However, decades of experiences from islet transplantation show that ischemia-induced islet cell death after transplant severely limits the efficacy of the therapy. It is unclear to what extent human SCIPC are susceptible to ischemia. In this study, we show that more than half of SCIPC die shortly after transplantation. Nutrient deprivation and hypoxia acted synergistically to kill SCIPC in vitro. Amino acid supplementation rescued SCIPC from nutrient deprivation, likely by providing cellular energy. Generating SCIPC under physiological oxygen tension of 5% conferred hypoxia resistance without affecting their differentiation or function. A two-pronged strategy of physiological oxygen acclimatization during differentiation and amino acid supplementation during transplantation significantly improved SCIPC survival after transplant.

Brg1 promotes both tumor-suppressive and oncogenic activities at distinct stages of pancreatic cancer formation.

Pancreatic ductal adenocarcinoma (PDA) develops predominantly through pancreatic intraepithelial neoplasia (PanIN) and intraductal papillary mucinous neoplasm (IPMN) precursor lesions. Pancreatic acinar cells are reprogrammed to a "ductal-like" state during PanIN-PDA formation. Here, we demonstrate a parallel mechanism operative in mature duct cells during which functional cells undergo "ductal retrogression" to form IPMN-PDA. We further identify critical antagonistic roles for Brahma-related gene 1 (Brg1), a catalytic subunit of the SWI/SNF complexes, during IPMN-PDA development. In mature duct cells, Brg1 inhibits the dedifferentiation that precedes neoplastic transformation, thus attenuating tumor initiation. In contrast, Brg1 promotes tumorigenesis in full-blown PDA by supporting a mesenchymal-like transcriptional landscape. We further show that JQ1, a drug that is currently being tested in clinical trials for hematological malignancies, impairs PDA tumorigenesis by both mimicking some and inhibiting other Brg1-mediated functions. In summary, our study demonstrates the context-dependent roles of Brg1 and points to potential therapeutic treatment options based on epigenetic regulation in PDA.

De novo assembly and characterization of a maternal and developmental transcriptome for the emerging model crustacean Parhyale hawaiensis.

BACKGROUND: Arthropods are the most diverse animal phylum, but their genomic resources are relatively few. While the genome of the branchiopod Daphnia pulex is now available, no other large-scale crustacean genomic resources are available for comparison. In particular, genomic resources are lacking for the most tractable laboratory model of crustacean development, the amphipod Parhyale hawaiensis. Insight into shared and divergent characters of crustacean genomes will facilitate interpretation of future developmental, biomedical, and ecological research using crustacean models. RESULTS: To generate a transcriptome enriched for maternally provided and zygotically transcribed developmental genes, we created cDNA from ovaries and embryos of P. hawaiensis. Using 454 pyrosequencing, we sequenced over 1.1 billion bases of this cDNA, and assembled them de novo to create, to our knowledge, the second largest crustacean genomic resource to date. We found an unusually high proportion of C2H2 zinc finger-containing transcripts, as has also been reported for the genome of the pea aphid Acyrthosiphon pisum. Consistent with previous reports, we detected trans-spliced transcripts, but found that they did not noticeably impact transcriptome assembly. Our assembly products yielded 19,067 unique BLAST hits against nr (E-value cutoff e-10). These included over 400 predicted transcripts with significant similarity to D. pulex sequences but not to sequences of any other animal. Annotation of several hundred genes revealed P. hawaiensis homologues of genes involved in development, gametogenesis, and a majority of the members of six major conserved metazoan signaling pathways. CONCLUSIONS: The amphipod P. hawaiensis has higher transcript complexity than known insect transcriptomes, and trans-splicing does not appear to be a major contributor to this complexity. We discuss the importance of a reliable comparative genomic framework within which to consider findings from new crustacean models such as D. pulex and P. hawaiensis, as well as the need for development of further substantial crustacean genomic resources.