Transcription factors TEAD2 and E2A globally repress acetyl-CoA synthesis to promote tumorigenesis.

Acetyl-coenzyme A (acetyl-CoA) plays an important role in metabolism, gene expression, signaling, and other cellular processes via transfer of its acetyl group to proteins and metabolites. However, the synthesis and usage of acetyl-CoA in disease states such as cancer are poorly characterized. Here, we investigated global acetyl-CoA synthesis and protein acetylation in a mouse model and patient samples of hepatocellular carcinoma (HCC). Unexpectedly, we found that acetyl-CoA levels are decreased in HCC due to transcriptional downregulation of all six acetyl-CoA biosynthesis pathways. This led to hypo-acetylation specifically of non-histone proteins, including many enzymes in metabolic pathways. Importantly, repression of acetyl-CoA synthesis promoted oncogenic dedifferentiation and proliferation. Mechanistically, acetyl-CoA synthesis was repressed by the transcription factors TEAD2 and E2A, previously unknown to control acetyl-CoA synthesis. Knockdown of TEAD2 and E2A restored acetyl-CoA levels and inhibited tumor growth. Our findings causally link transcriptional reprogramming of acetyl-CoA metabolism, dedifferentiation, and cancer

Elevated arginine levels in liver tumors promote metabolic reprogramming and tumor growth

Arginine auxotropy, due to reduced expression of urea cycle genes, is common in cancer. However, little is known about the levels of arginine in these cancers. Here, we report that arginine levels are elevated in hepatocellular carcinoma (HCC) despite reduced expression of urea cycle enzymes. Liver tumors accumulate high levels specifically of arginine via increased uptake and, more importantly, via suppression of arginine-to-polyamine conversion due to reduced arginase 1 (ARG1) and agmatinase (AGMAT) expression. Furthermore, the high levels of arginine are required for tumor growth. Mechanistically, high levels of arginine promote tumorigenesis via transcriptional regulation of metabolic genes, including upregulation of asparagine synthetase (ASNS). ASNS-derived asparagine further enhances arginine uptake, creating a positive feedback loop to sustain high arginine levels and oncogenic metabolism. Thus, arginine is a novel second messenger-like molecule that reprograms metabolism to promote tumor growth

A Multi-Platform Flow Device for Microbial (Co-) Cultivation and Microscopic Analysis

Novel microbial cultivation platforms are of increasing interest to researchers in academia and industry. The development of materials with specialized chemical and geometric properties has opened up new possibilities in the study of previously unculturable microorganisms and has facilitated the design of elegant, high-throughput experimental set-ups. Within the context of the international Genetically Engineered Machine (iGEM) competition, we set out to design, manufacture, and implement a flow device that can accommodate multiple growth platforms, that is, a silicon nitride based microsieve and a porous aluminium oxide based microdish. It provides control over (co-)culturing conditions similar to a chemostat, while allowing organisms to be observed microscopically. The device was designed to be affordable, reusable, and above all, versatile. To test its functionality and general utility, we performed multiple experiments with Escherichia coli cells harboring synthetic gene circuits and were able to quantitatively study emerging expression dynamics in real-time via fluorescence microscopy. Furthermore, we demonstrated that the device provides a unique environment for the cultivation of nematodes, suggesting that the device could also prove useful in microscopy studies of multicellular microorganisms

Overview of the BioBrick parts used.

*<p>co-cultivated with RFP containing BioBrick part as control for leakage.</p

Oscillating GFP expression observed in microdish wells.

<p>Fluorescent <i>E. coli</i> cells in the wells of the microdish showing variations in signal strength over time. The graph depicts variations plotted with the image analysis and processing tool ImageJ. The x-axis represents time, and the y-axis represents fluorescence (in arbitrary units and with a variance of maximally 0.01 for the normalised data of 5 wells). Below the graph are microscopic images of fluorescent bacteria in the cultivation chip wells at different intervals using identical illumination conditions and CCD camera exposure times. The time points at which the images were taken are indicated with an asterisk.</p

Schematic representation of the flow device.

<p>A) Schematic representation of the flow device, with the dimensions in mm. Depicted in red and blue are the in- and outflow channels of the top compartment (light green). The respective in- and outflow channels of the lower compartment (yellow) are given in purple and dark green. B) Electron microscopy image of a microsieve. C) Electron microscopy image of a microdish. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036982#pone.0036982.s001" target="_blank">File S1</a> for more views of the device.</p

Fluorescent nematodes observed in the flow device.

<p>A) Nematodes floating over the wells while the chamber is filled with liquid. The fluorescent oesophagus in the front side of the nematode is clearly visible. B) Nematode trapped in a well filled with fluorescent <i>E. coli</i> cells after removing the liquid from the chamber. C) Next day: A nematode after consuming all fluorescent bacteria from the well, resulting in observable fluorescence in the nematode intestine.</p

Co-cultivation of cells separated by a microsieve.

<p>Increase of GFP expression of inducible cells on the sieve after inoculation of inducer cells below. Graph plotted with the image analysis and processing tool ImageJ. The x-axis corresponds to time and the y-axis shows the detected GFP signal (in arbitrary units). Below: a number of representative images of the microsieve. The time points at which the images were taken are indicated with an asterisk.</p

Cell retention on the microsieve.

<p>Retained clusters of fluorescent <i>E. coli</i> cells on the sieve (100x magnification). The diagonal light grey bands are the permeable areas of the microsieve that contain the pores.</p