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Archive - Sep 20, 2015

Serum Exosomal MicroRNAs May Be Novel Biomarkers for Hepatocellular Carcinoma (HCC)

In an open-access article published online on September 18, 2015 in Experimental & Molecular Medicine, scientists from Sungkyunkwan University School of Medicine in Seoul, Korea, show that levels of the serum exosomal microRNAs miR-18a, miR-221, miR-222, and miR-224 were significantly higher in patients with hepatocellular carcinoma (HCC) than in patients with either chronic hepatitis B (CHB) or liver cirrhosis (LC). Meanwhile, the scientists also showed that that the serum exosomal levels of miR-101, miR-106b, miR-122, and miR-195 were lower in those with HCC than in those with CHB. The scientists conclude that their data suggests that serum exosomal microRNA may be used as novel biomarkers for HCC. The EMM article is titled “Serum Exosomal MicroRNAs As Novel Biomarkers for Hepatocellular Carcinoma.”

[Experimental & Molecular Medicine article]

3.5-Billion-Year-Old Tree of Life Contains 2.3 Million Named Species; First Attempt at Comprehensive Tree Ever Released; First Draft Is Compiled from Digitally Available Smaller Trees; Tens of Millions of Species Estimated to Have Lived on Earth

A first draft of the "tree of life" for the roughly 2.3 million named species of animals, plants, fungi, and microbes has been released. A collaborative effort among eleven institutions, the tree depicts the relationships among living things as they diverged from one another over time, tracing back to the beginning of life on Earth more than 3.5 billion years ago. Tens of thousands of smaller trees have been published over the years for select branches of the tree of life -- some containing upwards of 100,000 species -- but this is the first time those results have been combined into a single tree that encompasses all of life. The end result is a digital resource that is available free online for anyone to use or edit, much like a "Wikipedia" for evolutionary trees. "This is the first real attempt to connect the dots and put it all together," said principal investigator Dr. Karen Cranston of Duke University. "Think of it as Version 1.0." The current version of the tree -- along with the underlying data and source code -- is available to browse and download at https://tree.opentreeoflife.org. It is also described in an open-access article appearing online on September 18, 2015 in PNAS. The article is titled “Synthesis of Phylogeny and Taxonomy Into a Comprehensive Tree of Life.” Evolutionary trees, branching diagrams that often look like a cross between a candelabra and a subway map, aren't just for figuring out whether aardvarks are more closely related to moles or manatees, or pinpointing a slime mold's closest cousins. Understanding how the millions of species on Earth are related to one another helps scientists discover new drugs, increase crop and livestock yields, and trace the origins and spread of infectious diseases such as HIV, Ebola, and influenza.

Cell Death Enzyme RIPK3 Found to Trigger Signals from Mitochondria to Natural Killer T Cells, Activating Inflammatory Cytokines; Newly Identified Pathway Influences Both Autoimmunity and Immune Response to Tumors

Scientists at The Scripps Research Institute (TSRI) have discovered a new role for an enzyme involved in cell death. Their study shows how the enzyme, called RIPK3 (image), relays signals between the cell's mitochondria "powerhouses" and the immune system. The new study shows that this crosstalk is important, not only for launching immune responses against tumors, but also for regulating the inflammatory responses that may result in autoimmune diseases. "This finding could be helpful for developing strategies to target cancer and inflammatory diseases," said TSRI Assistant Professor of Immunology Young Jun Kang, who collaborated on the study with the laboratory of TSRI Institute Professor Richard A. Lerner, who is also the Lita Annenberg Hazen Professor of Immunochemistry at TSRI. The study was published online on September 18, 2015 in an open-access article in Nature Communications. The article is titled “Regulation of NKT Cell-Mediated Immune Responses to Tumors and Liver Inflammation by Mitochondrial PGAM5-Drp1 Signaling." Previous studies have shown RIPK3 controls the induction of a type of programmed cell death, called necroptosis, which protects the body from harmful mutations and infections. However, scientists had not fully understood RIPK3's role in the immune system. In this new study, the scientists investigated the role of RIPK3 by studying RIPK3-deficient mice. The research results suggest that RIPK3 regulates the activation of natural killer T cells (NKTs), the immune cells that play dual roles in the development of autoimmune diseases and the destruction of cancers. RIPK3 does not directly cause necroptosis; rather, it regulates the activity of a mitochondrial enzyme (PGAM5) to trigger the expression of inflammatory cytokines in NKTs.