Recombinant adeno associated viral (AAV) vector type 9 delivery of Ex1-Q138-mutant huntingtin in the rat striatum as a short-time model for in vivo studies in drug discovery

Huntington's disease (HD) is an inherited neurodegenerative disorder characterized by dyskinesia, cognitive impairment and emotional disturbances, presenting progressive neurodegeneration in the striatum and intracellular mutant Huntingtin (mHTT) aggregates in various areas of the brain. Recombinant Adeno Associated Viral (rAAV) vectors have been successfully used to transfer foreign genes to the brain of adult animals. In the present study we report a novel in vivo rat HD model obtained by stereotaxic injection of rAAV serotype2/9 containing Exon1-Q138 mHTT (Q138) and Exon1-Q17 wild type HTT (Q17; control), respectively in the right and in the left striatum, and expressed as C-terminal GFP fusions to facilitate detection of infected cells and aggregate production. Immunohistochemical analysis of brain slices from animals sacrificed twenty-one days after viral infection showed that Q138 injection resulted in robust formation of GFP-positive aggregates in the striatum, increased GFAP and microglial activation and neurodegeneration, with little evidence of any of these events in contralateral tissue infected with wild type (Q17) expressing construct. Differences in the relative metabolite concentrations (N-Acetyl Aspartate/Creatine and Myo-Inositol/Creatine) were observed by H1 MR Spectroscopy. By quantitative RT-PCR we also demonstrated that mHTT induced changes in the expression of genes previously shown to be altered in other rodent HD models. Importantly, administration of reference compounds previously shown to ameliorate the aggregation and neurodegeneration phenotypes in preclinical HD models was demonstrated to revert the mutant HTT-dependent effects in our model. In conclusion, the AAV2/9-Q138/Q17 exon 1 HTT stereotaxic injection represents a useful first-line in vivo preclinical model for studying the biology of mutant HTT exon 1 in the striatum and to provide early evidence of efficacy of therapeutic approaches

Polyglutamine expansion affects huntingtin conformation in multiple Huntington's disease models

Conformational changes in disease-associated or mutant proteins represent a key pathological aspect of Huntington's disease (HD) and other protein misfolding diseases. Using immunoassays and biophysical approaches, we and others have recently reported that polyglutamine expansion in purified or recombinantly expressed huntingtin (HTT) proteins affects their conformational properties in a manner dependent on both polyglutamine repeat length and temperature but independent of HTT protein fragment length. These findings are consistent with the HD mutation affecting structural aspects of the amino-terminal region of the protein, and support the concept that modulating mutant HTT conformation might provide novel therapeutic and diagnostic opportunities. We now report that the same conformational TR-FRET based immunoassay detects polyglutamine-and temperaturedependent changes on the endogenously expressed HTT protein in peripheral tissues and post-mortem HD brain tissue, as well as in tissues from HD animal models. We also find that these temperatureand polyglutamine-dependent conformational changes are sensitive to bona-fide phosphorylation on S13 and S16 within the N17 domain of HTT. These findings provide key clinical and preclinical relevance to the conformational immunoassay, and provide supportive evidence for its application in the development of therapeutics aimed at correcting the conformation of polyglutamine-expanded proteins as well as the pharmacodynamics readouts to monitor their efficacy in preclinical models and in HD patients

The 5-Hydroxymethylcytosine Landscape of Prostate Cancer

Analysis of DNA methylation is a valuable tool to understand disease progression and is increasingly being used to create diagnostic and prognostic clinical biomarkers. While conversion of cytosine to 5-methylcytosine (5mC) commonly results in transcriptional repression, further conversion to 5-hydroxymethylcytosine (5hmC) is associated with transcriptional activation. Here we perform the first study integrating whole-genome 5hmC with DNA, 5mC, and transcriptome sequencing in clinical samples of benign, localized, and advanced prostate cancer. 5hmC is shown to mark activation of cancer drivers and downstream targets. Furthermore, 5hmC sequencing revealed profoundly altered cell states throughout the disease course, characterized by increased proliferation, oncogenic signaling, dedifferentiation, and lineage plasticity to neuroendocrine and gastrointestinal lineages. Finally, 5hmC sequencing of cell-free DNA from patients with metastatic disease proved useful as a prognostic biomarker able to identify an aggressive subtype of prostate cancer using the genes TOP2A and EZH2, previously only detectable by transcriptomic analysis of solid tumor biopsies. Overall, these findings reveal that 5hmC marks epigenomic activation in prostate cancer and identify hallmarks of prostate cancer progression with potential as biomarkers of aggressive disease. SIGNIFICANCE: In prostate cancer, 5-hydroxymethylcytosine delineates oncogene activation and stage-specific cell states and can be analyzed in liquid biopsies to detect cancer phenotypes. See related article by Wu and Attard, p. 3880.publishedVersionPeer reviewe

Phospho-S129 Alpha-Synuclein Is Present in Human Plasma but Not in Cerebrospinal Fluid as Determined by an Ultrasensitive Immunoassay

Accumulation and aggregation of misfolded alpha-synuclein is believed to be a cause of Parkinson's disease (PD). Phosphorylation of alpha-synuclein at S129 is known to be associated with the pathological misfolding process, but efforts to investigate the relevance of this post-translational modification for pathology have been frustrated by difficulties in detecting and quantifying it in relevant samples. We report novel, ultrasensitive immunoassays based on single-molecule counting technology, useful for detecting alpha-synuclein and its S129 phosphorylated form in clinical samples in the low pg/ml range. Using human CSF and plasma samples, we find levels of alpha-synuclein comparable to those previously reported. However, while alpha-synuclein phosphorylated on S129 could easily be detected in human plasma, where its detection is extremely sensitive to protein phosphatases, its levels in CSF were undetectable, with a possible influence of a matrix effect. In plasma samples from a small test cohort comprising 5 PD individuals and five age-matched control individuals we find that pS129 alpha-synuclein levels are increased in PD plasma samples, in line with previous reports. We conclude that pS129 alpha-synuclein is not detectable in CSF and recommend the addition of phosphatase inhibitors to plasma samples at the time of collection. Moreover, the findings obtained on the small cohort of clinical plasma samples point to plasma pS129 alpha-synuclein levels as a candidate diagnostic biomarker in PD

Ultrasensitive quantitative measurement of huntingtin phosphorylation at residue S13

Huntington's disease (HD) is a progressive neurodegenerative disorder caused by an expansion of a CAG triplet repeat (encoding for a polyglutamine tract) within the first exon of the huntingtin gene. Expression of the mutant huntingtin (mHTT) protein can result in the production of N-terminal fragments with a robust propensity to form oligomers and aggregates, which may be causally associated with HD pathology. Several lines of evidence indicate that N17 phosphorylation or pseudophosphorylation at any of the residues T3, S13 or S16, alone or in combination, modulates mHTT aggregation, subcellular localization and toxicity. Consequently, increasing N17 phosphorylation has been proposed as a potential therapeutic approach. However, developing genetic/pharmacological tools to quantify these phosphorylation events is necessary in order to subsequently develop tool modulators, which is difficult given the transient and incompletely penetrant nature of such post-translational modifications. Here we describe the first ultrasensitive sandwich immunoassay that quantifies HTT phosphorylated at residue S13 and demonstrate its utility for specific analyte detection in preclinical models of HD. (C) 2019 Published by Elsevier Inc

Phosphorylation of huntingtin at residue T3 is decreased in Huntington's disease and modulates mutant huntingtin protein conformation.

Posttranslational modifications can have profound effects on the biological and biophysical properties of proteins associated with misfolding and aggregation. However, their detection and quantification in clinical samples and an understanding of the mechanisms underlying the pathological properties of misfolding- and aggregation-prone proteins remain a challenge for diagnostics and therapeutics development. We have applied an ultrasensitive immunoassay platform to develop and validate a quantitative assay for detecting a posttranslational modification (phosphorylation at residue T3) of a protein associated with polyglutamine repeat expansion, namely Huntingtin, and characterized its presence in a variety of preclinical and clinical samples. We find that T3 phosphorylation is greatly reduced in samples from Huntington's disease models and in Huntington's disease patients, and we provide evidence that bona-fide T3 phosphorylation alters Huntingtin exon 1 protein conformation and aggregation properties. These findings have significant implications for both mechanisms of disease pathogenesis and the development of therapeutics and diagnostics for Huntington's disease

TBK1 phosphorylates mutant Huntingtin and suppresses its aggregation and toxicity in Huntington's disease models

Phosphorylation of the N‐terminal domain of the huntingtin (HTT ) protein has emerged as an important regulator of its localization, structure, aggregation, clearance and toxicity. However, validation of the effect of bona fide phosphorylation in vivo and assessing the therapeutic potential of targeting phosphorylation for the treatment of Huntington's disease (HD ) require the identification of the enzymes that regulate HTT phosphorylation. Herein, we report the discovery and validation of a kinase, TANK ‐binding kinase 1 (TBK 1), that efficiently phosphorylates full‐length and N‐terminal HTT fragments in vitro (at S13/S16), in cells (at S13) and in vivo . TBK 1 expression in HD models (cells, primary neurons, and Caenorhabditis elegans ) increases mutant HTT exon 1 phosphorylation and reduces its aggregation and cytotoxicity. We demonstrate that the TBK 1‐mediated neuroprotective effects are due to phosphorylation‐dependent inhibition of mutant HTT exon 1 aggregation and an increase in autophagic clearance of mutant HTT . These findings suggest that upregulation and/or activation of TBK 1 represents a viable strategy for the treatment of HD by simultaneously lowering mutant HTT levels and blocking its aggregation

Polyglutamine- and temperature-dependent conformational rigidity in mutant huntingtin revealed by immunoassays and circular dichroism spectroscopy.

BACKGROUND:In Huntington's disease, expansion of a CAG triplet repeat occurs in exon 1 of the huntingtin gene (HTT), resulting in a protein bearing>35 polyglutamine residues whose N-terminal fragments display a high propensity to misfold and aggregate. Recent data demonstrate that polyglutamine expansion results in conformational changes in the huntingtin protein (HTT), which likely influence its biological and biophysical properties. Developing assays to characterize and measure these conformational changes in isolated proteins and biological samples would advance the testing of novel therapeutic approaches aimed at correcting mutant HTT misfolding. Time-resolved Förster energy transfer (TR-FRET)-based assays represent high-throughput, homogeneous, sensitive immunoassays widely employed for the quantification of proteins of interest. TR-FRET is extremely sensitive to small distances and can therefore provide conformational information based on detection of exposure and relative position of epitopes present on the target protein as recognized by selective antibodies. We have previously reported TR-FRET assays to quantify HTT proteins based on the use of antibodies specific for different amino-terminal HTT epitopes. Here, we investigate the possibility of interrogating HTT protein conformation using these assays. METHODOLOGY/PRINCIPAL FINDINGS:By performing TR-FRET measurements on the same samples (purified recombinant proteins or lysates from cells expressing HTT fragments or full length protein) at different temperatures, we have discovered a temperature-dependent, reversible, polyglutamine-dependent conformational change of wild type and expanded mutant HTT proteins. Circular dichroism spectroscopy confirms the temperature and polyglutamine-dependent change in HTT structure, revealing an effect of polyglutamine length and of temperature on the alpha-helical content of the protein. CONCLUSIONS/SIGNIFICANCE:The temperature- and polyglutamine-dependent effects observed with TR-FRET on HTT proteins represent a simple, scalable, quantitative and sensitive assay to identify genetic and pharmacological modulators of mutant HTT conformation, and potentially to assess the relevance of conformational changes during onset and progression of Huntington's disease