The accumulation of protein aggregates is toxic and linked to different diseases such as neurodegenerative disorders, but the role of the immune system to target and destroy aggregate-carrying cells is still relatively unknown. Here we show a substrate-specific presentation of antigenic peptides to the direct MHC class I pathway via autophagy. We observed no difference in presentation of peptides derived from the viral EBNA1 protein following suppression of autophagy by knocking down Atg5 and Atg12. However, the same knock down treatment suppressed the presentation from ovalbumin. Fusing the aggregate-prone poly-glutamine (PolyQ) to the ovalbumin had no effect on antigen presentation via autophagy. Interestingly, fusing the EBNA1-derived gly-ala repeat (GAr) sequence to ovalbumin rendered the presentation Atg5/12 independent. We also demonstrate that the relative levels of protein expression did not affect autophagy-mediated antigen presentation. These data suggest a substrate-dependent presentation of antigenic peptides for the MHC class I pathway via autophagy and indicate that the GAr of the EBNA1 illustrates a novel virus-mediated mechanism for immune evasion of autophagy-dependent antigen presentation.
Spinocerebellar ataxia type-1 (SCA1) is caused by an abnormally expanded polyglutamine (polyQ) tract in ataxin-1. These expansions are responsible for protein misfolding and self-assembly into intranuclear inclusion bodies (IIBs) that are somehow linked to neuronal death. However, owing to lack of a suitable cellular model, the downstream consequences of IIB formation are yet to be resolved. Here, we describe a nuclear protein aggregation model of pathogenic human ataxin-1 and characterize IIB effects. Using an inducible Sleeping Beauty transposon system, we overexpressed the ATXN1(Q82) gene in human mesenchymal stem cells that are resistant to the early cytotoxic effects caused by the expression of the mutant protein. We characterized the structure and the protein composition of insoluble polyQ IIBs which gradually occupy the nuclei and are responsible for the generation of reactive oxygen species. In response to their formation, our transcriptome analysis reveals a cerebellum-specific perturbed protein interaction network, primarily affecting protein synthesis. We propose that insoluble polyQ IIBs cause oxidative and nucleolar stress and affect the assembly of the ribosome by capturing or down-regulating essential components. The inducible cell system can be utilized to decipher the cellular consequences of polyQ protein aggregation. Our strategy provides a broadly applicable methodology for studying polyQ diseases.
- MeSH
- Ataxin-1 genetics metabolism MeSH
- Intranuclear Inclusion Bodies * metabolism MeSH
- Nuclear Proteins genetics metabolism MeSH
- Humans MeSH
- Oxidative Stress MeSH
- Nerve Tissue Proteins * genetics metabolism MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Sandwich ELISA-based methods use Abs that target the expanded polyglutamine (polyQ) tract to quantify mutant huntingtin (mHTT). Using Meso Scale Discovery (MSD) assay, the mHTT signal detected with MW1 Ab correlated with polyQ length and doubled with a difference of only 7 glutamine residues between equivalent amounts of purified mHTTexon1 proteins. Similar polyQ length-dependent effects on MSD signals were confirmed using endogenous full length mHTT from brains of Huntington's disease (HD) knock-in (KI) mice. We used this avidity bias to devise a method to assess average CAG repeat instability at the protein level in a mixed population of HTT proteins present in tissues. Signal detected for average polyQ length quantification at the protein level by our method exhibited a strong correlation with average CAG repeat length at the genomic DNA level determined by PCR method in striatal tissue homogenates from HdhQ140 KI mice and in human HD postmortem cortex. This work establishes that CAG repeat instability in mutant HTT is reflected at the protein level.
- MeSH
- DNA genetics MeSH
- Exons genetics MeSH
- Trinucleotide Repeat Expansion genetics MeSH
- Humans MeSH
- Mice, Inbred C57BL MeSH
- Mice, Transgenic MeSH
- Peptides genetics MeSH
- Huntingtin Protein chemistry genetics MeSH
- Antibodies metabolism MeSH
- Amino Acid Sequence MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Huntingtonova nemoc (HN) je autozomálně dominantně dědičné neurodegenerativní onemocnění charakterizované motorickým deficitem, poruchami chování a kognitivních funkcí. Postihuje především mozek, přičemž změny související s HN byly nalezeny rovněž i v periferních tkáních. Některé z nich mohou být způsobeny přímou expresí mutovaného huntingtinu, jehož nejvyšší koncentrace byly nalezeny v mozku a varlatech pacientů s HN. V roce 2009 jsme vytvořili miniprasečí model HN (TgHD) exprimující N‑terminální (548aa) část lidského mutovaného huntingtinu kódujícího 124 CAG/CAA repetic. Na základě předchozích experimentů byla u TgHD kanců od 13. měsíce věku zjištěna zhoršená schopnost reprodukce a snížený počet spermií v ejakulátu. Cílem této studie bylo prokázat změny ve varlatech 24 měsíčních transgenních kanců (F2 generace in vivo) pomocí neinvazivní metody 31P magnetické rezonanční spektroskopie a provést imunohistochemickou analýzu TgHD spermií odebraných z F1 a F3 generace před projevením se klinických příznaků HN. Na základě vyšetření magnetickou rezonancí bylo zjištěno signifikantní snížení relativní koncentrace fosfodiesterů v testikulárním parenchymu TgHD kanců v porovnání s netransgenními jedinci (WT) stejné věkové kategorie. Rovněž imunohistochemická analýza spermií odebraných z TgHD a WT kanců odhalila výrazné anti‑polyQ specifické (klon 3B5H10) stejně tak i signifikantně zvýšené anti‑huntingtin (klon EPR5526) barvení v bičících transgenních spermiích v porovnání s netransgenními spermiemi. Na základě našich výsledků lze usuzovat, že lidský mutovaný huntingtin má negativní vliv na metabolizmus varlat a způsobuje zvýšený výskyt abnormalit spermií. Klíčová slova: Huntingtonova nemoc – varlata – spermie – miniprase – magnetická rezonanční spektroskopie Autoři deklarují, že v souvislosti s předmětem studie nemají žádné komerční zájmy. Redakční rada potvrzuje, že rukopis práce splnil ICMJE kritéria pro publikace zasílané do biomedicínských časopisů.
Huntington's disease (HD) is an inherited autosomal neurodegenerative disorder characterized by motor dysfunctions, behavioral and cognitive disturbances. It affects predominantly the brain, however, changes were found also in peripheral tissues. Some of these changes can result from direct expression of mutant huntingtin; its highest levels have been found in the brain and testes. In 2009 we established a minipig model of HD (TgHD) expressing N‑terminal (548aa) part of human mutated huntingtin encoded 124 CAG/CAA repeats. Previous research has revealed the presence of reduced fertility and fewer spermatozoa per ejaculate in TgHD boars started at 13 months of age. The aim of this study was to determine changes in the testes of 24 months old transgenic boars (F2 generation in vivo) using non‑invasive methodology of 31P magnetic resonance (MR) spectroscopy as well as to perform imunohistochemical analysis of TgHD sperm collected fromform F1 and F3 generation before HD onset. The results have shown significant reduction of relative phosphodiester concentration in testicular parenchyma of TgHD boars compared to wild type (WT) ones of the same ages. Moreover immunohistochemical analysis of sperm collected from TgHD and WT have revealed exclusive anti‑polyQ specific (clone 3B5H10) as well as significantly increased anti‑huntingtin (clone EPR5526) staining in transgenic spermatozoa tails in comparison with WT counterparts. Thus, our results are suggestive of the negative impact of human mutated huntingtin on testes metabolism as well as sperm abnormalities.
- Keywords
- huntingtin,
- MeSH
- Animals, Genetically Modified MeSH
- Huntington Disease * genetics metabolism MeSH
- Immunohistochemistry statistics & numerical data MeSH
- Magnetic Resonance Spectroscopy statistics & numerical data MeSH
- Swine, Miniature MeSH
- Mutation MeSH
- Swine MeSH
- Nerve Tissue Proteins genetics metabolism MeSH
- Spermatozoa * chemistry MeSH
- Testis * metabolism pathology MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Animals MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
Huntington's disease (HD) is the most common inherited neurodegenerative disorder among polyglutamine (polyQ) diseases caused by cytosine-adenine-guanine repeat expansion in exon 1 of the huntingtin gene whose translation results in polyQ stretch in the N-terminus of the huntingtin protein (HD protein). This mutation significantly affects huntingtin conformation, proteolysis, PTMs, as well as its ability to bind interacting proteins. As a consequence, a variety of cellular mechanisms such as transcription, mitochondrial energy metabolism, axonal transport, neuronal vulnerability to oxidative stress, neurotransmission, and immune response are altered and involved in the pathogenesis of HD. Promising candidate molecular biomarkers of HD have emerged from proteomic studies. Recent analyses focused on HD protein itself, its PTM, and interacting proteins, which are of great importance for disease course. Furthermore, brain, body fluids, and immune system are intensively studied in order to search for additional proteins with a view to their use as a biomarker(s) or set of biomarkers in clinical trials in HD translational research.
- MeSH
- Biomarkers metabolism MeSH
- Huntington Disease metabolism therapy MeSH
- Humans MeSH
- Nerve Tissue Proteins metabolism MeSH
- Proteome analysis MeSH
- Proteomics methods MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
The density functional code deMon2k employs a fitted density throughout (Auxiliary Density Functional Theory), which offers a great speed advantage without sacrificing necessary accuracy. Powerful Quantum Mechanical/Molecular Mechanical (QM/MM) approaches are reviewed. Following an overview of the basic features of deMon2k that make it efficient while retaining accuracy, three QM/MM implementations are compared and contrasted. In the first, deMon2k is interfaced with the CHARMM MM code (CHARMM-deMon2k); in the second MM is coded directly within the deMon2k software; and in the third the Chemistry in Ruby (Cuby) wrapper is used to drive the calculations. Cuby is also used in the context of constrained-DFT/MM calculations. Each of these implementations is described briefly; pros and cons are discussed and a few recent applications are described briefly. Applications include solvated ions and biomolecules, polyglutamine peptides important in polyQ neurodegenerative diseases, copper monooxygenases and ultra-rapid electron transfer in cryptochromes.
- MeSH
- Quantum Theory MeSH
- Humans MeSH
- Models, Molecular MeSH
- Peptides chemistry MeSH
- Molecular Dynamics Simulation MeSH
- Software * MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
BACKGROUND: QTL cloning for the discovery of genes underlying polygenic traits has historically been cumbersome in long-lived perennial plants like Populus. Linkage disequilibrium-based association mapping has been proposed as a cloning tool, and recent advances in high-throughput genotyping and whole-genome resequencing enable marker saturation to levels sufficient for association mapping with no a priori candidate gene selection. Here, multiyear and multienvironment evaluation of cell wall phenotypes was conducted in an interspecific P. trichocarpa x P. deltoides pseudo-backcross mapping pedigree and two partially overlapping populations of unrelated P. trichocarpa genotypes using pyrolysis molecular beam mass spectrometry, saccharification, and/ or traditional wet chemistry. QTL mapping was conducted using a high-density genetic map with 3,568 SNP markers. As a fine-mapping approach, chromosome-wide association mapping targeting a QTL hot-spot on linkage group XIV was performed in the two P. trichocarpa populations. Both populations were genotyped using the 34 K Populus Infinium SNP array and whole-genome resequencing of one of the populations facilitated marker-saturation of candidate intervals for gene identification. RESULTS: Five QTLs ranging in size from 0.6 to 1.8 Mb were mapped on linkage group XIV for lignin content, syringyl to guaiacyl (S/G) ratio, 5- and 6-carbon sugars using the mapping pedigree. Six candidate loci exhibiting significant associations with phenotypes were identified within QTL intervals. These associations were reproducible across multiple environments, two independent genotyping platforms, and different plant growth stages. cDNA sequencing for allelic variants of three of the six loci identified polymorphisms leading to variable length poly glutamine (PolyQ) stretch in a transcription factor annotated as an ANGUSTIFOLIA C-terminus Binding Protein (CtBP) and premature stop codons in a KANADI transcription factor as well as a protein kinase. Results from protoplast transient expression assays suggested that each of the polymorphisms conferred allelic differences in the activation of cellulose, hemicelluloses, and lignin pathway marker genes. CONCLUSION: This study illustrates the utility of complementary QTL and association mapping as tools for gene discovery with no a priori candidate gene selection. This proof of concept in a perennial organism opens up opportunities for discovery of novel genetic determinants of economically important but complex traits in plants.
- MeSH
- Alleles MeSH
- Cell Wall genetics MeSH
- Cellulose metabolism MeSH
- Phenotype MeSH
- Genetic Linkage MeSH
- Genotype MeSH
- Polymorphism, Single Nucleotide MeSH
- Lignin biosynthesis MeSH
- Lod Score MeSH
- Quantitative Trait Loci MeSH
- Chromosome Mapping MeSH
- Populus genetics MeSH
- Genes, Plant * MeSH
- Plant Proteins chemistry genetics MeSH
- Base Sequence MeSH
- Sequence Alignment MeSH
- Transcription Factors chemistry genetics MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
- Keywords
- PolyQ nemoci,
- MeSH
- Ataxins isolation & purification adverse effects MeSH
- Atropine isolation & purification adverse effects MeSH
- Bulbo-Spinal Atrophy, X-Linked diagnosis etiology MeSH
- Friedreich Ataxia diagnosis etiology MeSH
- Glutamine * genetics metabolism MeSH
- Huntington Disease diagnosis etiology MeSH
- Humans MeSH
- Myoclonic Epilepsies, Progressive diagnosis etiology MeSH
- Neurodegenerative Diseases MeSH
- Polynucleotides * MeSH
- Huntingtin Protein isolation & purification adverse effects MeSH
- TATA-Box Binding Protein isolation & purification MeSH
- Protein Aggregates * MeSH
- Spinocerebellar Ataxias diagnosis etiology MeSH
- Statistics as Topic MeSH
- Check Tag
- Humans MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
