N6-Furfuryladenine is protective in Huntington’s disease models by signaling huntingtin phosphorylation

© 2018 National Academy of Sciences. All Rights Reserved. The huntingtin N17 domain is a modulator of mutant huntingtin toxicity and is hypophosphorylated in Huntington’s disease (HD). We conducted high-content analysis to find compounds that could restore N17 phosphorylation. One lead compound from this screen was N6-furfuryladenine (N6FFA). N6FFA was protective in HD model neurons, and N6FFA treatment of an HD mouse model corrects HD phenotypes and eliminates cortical mutant huntingtin inclusions. We show that N6FFA restores N17 phosphorylation levels by being salvaged to a triphosphate form by adenine phosphoribosyltransferase (APRT) and used as a phosphate donor by casein kinase 2 (CK2). N6FFA is a naturally occurring product of oxidative DNA damage. Phosphorylated huntingtin functionally redistributes and colocalizes with CK2, APRT, and N6FFA DNA ad-ducts at sites of induced DNA damage. We present a model in which this natural product compound is salvaged to provide a triphosphate substrate to signal huntingtin phosphorylation via CK2 during low-ATP stress under conditions of DNA damage, with protective effects in HD model systems

Naïve Huntington’s disease microglia mount a normal response to inflammatory stimuli but display a partially impaired development of innate immune tolerance that can be counteracted by ganglioside GM1

Abstract Chronic activation and dysfunction of microglia have been implicated in the pathogenesis and progression of many neurodegenerative disorders, including Huntington’s disease (HD). HD is a genetic condition caused by a mutation that affects the folding and function of huntingtin (HTT). Signs of microglia activation have been observed in HD patients even before the onset of symptoms. It is unclear, however, whether pro-inflammatory microglia activation in HD results from cell-autonomous expression of mutant HTT, is the response of microglia to a diseased brain environment, or both. In this study, we used primary microglia isolated from HD knock-in (Q140) and wild-type (Q7) mice to investigate their response to inflammatory conditions in vitro in the absence of confounding effects arising from brain pathology. We show that naïve Q140 microglia do not undergo spontaneous pro-inflammatory activation and respond to inflammatory triggers, including stimulation of TLR4 and TLR2 and exposure to necrotic cells, with similar kinetics of pro-inflammatory gene expression as wild-type microglia. Upon termination of the inflammatory insult, the transcription of pro-inflammatory cytokines is tapered off in Q140 and wild-type microglia with similar kinetics. However, the ability of Q140 microglia to develop tolerance in response to repeated inflammatory stimulations is partially impaired in vitro and in vivo, potentially contributing to the establishment of chronic neuroinflammation in HD. We further show that ganglioside GM1, a glycosphingolipid with anti-inflammatory effects on wild-type microglia, not only decreases the production of pro-inflammatory cytokines and nitric oxide in activated Q140 microglia, but also dramatically dampen microglia response to re-stimulation with LPS in an experimental model of tolerance. These effects are independent from the expression of interleukin 1 receptor associated kinase 3 (Irak-3), a strong modulator of LPS signaling involved in the development of innate immune tolerance and previously shown to be upregulated by immune cell treatment with gangliosides. Altogether, our data suggest that external triggers are required for HD microglia activation, but a cell-autonomous dysfunction that affects the ability of HD microglia to acquire tolerance might contribute to the establishment of neuroinflammation in HD. Administration of GM1 might be beneficial to attenuate chronic microglia activation and neuroinflammation

Molecular characterization of microbial populations in a low-grade copper ore bioleaching test heap

13 páginas, 9 figuras.A culture-independent approach based on PCR amplification and denaturing gradient gel electrophoresis (DGGE) and sequencing of 16S rRNA gene fragments from both Bacteria and Archaea were used to analyze the microbial community inhabiting a low-grade copper sulfide run-of-mine (ROM) test heap of a project in Chile. In this paper, we summarize results of a 1- year monitoring study. Phylogenetic analyses of 16S rRNA fragments revealed that the retrieved sequences clustered together with Acidithiobacillus ferrooxidans, Leptospirillum ferriphilum, Ferroplasma acidiphilum and environmental clones related to them. In addition, some sequences were distantly related (b95% similarity in the 16S rRNA gene fragment analyzed) to cultured microorganisms from the Sulfurisphaera and Sulfobacillus genera. Thus, the prokaryotic assemblage might be mainly composed of sulfur- and iron-oxidizing microorganisms. The remaining sequences were related to uncultured chrenarchaeota clones or had only partial homology with known microorganisms. Attempts were made to estimate the dynamic of phylogenetic microbial groups in different stages of the leaching cycle and to correlate them with chemical and physical parameters in the heap. The temporal distribution of microbial 16S rRNA gene sequences could be divided in three periods. In the bioleaching cycle, first stage A. ferrooxidans and Sulfurisphaera-like archaea were dominant within each respective phylogenetic domain. In the second stage (from days 255 to 338), Leptospirillum and Ferroplasma groups were mainly detected, respectively. Finally (the third period from operation days 598 to 749), Sulfobacillus-like microorganisms became predominant, while Ferroplasma was the only Archaea detected. These data are now being used to obtain more detailed and quantitative information on prokaryotic community structure over time and to explore the nature of the community metabolic pathways. These results extend our knowledge on microbial dynamics in bioheaps, a key issue required to improve commercial applications.This work was supported by Minera Escondida Limitada, and funds provided by Chilean Government through FONDEF project D99I1026 and FONDECYT Project 1030441 from the Science and Technology Chilean Commission (CONICYT). EOC contribution was supported by the Programa Ramón y Cajal and REN2003-08333 from the Spanish Ministerio de Ciencia y Tecnología.Peer reviewe