抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Efficient analysis of very large amounts of raw data for peptide identification and protein quantification is a principal challenge in mass spectrometry (MS)-based proteomics. Here we describe MaxQuant, an integrated suite of algorithms specifically developed for high-resolution, quantitative MS data. Using correlation analysis and graph theory, MaxQuant detects peaks, isotope clusters and stable amino acid isotope-labeled (SILAC) peptide pairs as three-dimensional objects in m/z, elution time and signal intensity space. By integrating multiple mass measurements and correcting for linear and nonlinear mass offsets, we achieve mass accuracy in the p.p.b. range, a sixfold increase over standard techniques. We increase the proportion of identified fragmentation spectra to 73% for SILAC peptide pairs via unambiguous assignment of isotope and missed-cleavage state and individual mass precision. MaxQuant automatically quantifies several hundred thousand peptides per SILAC-proteome experiment and allows statistically robust identification and quantification of >4,000 proteins in mammalian cell lysates.

MaxQuant enables high peptide identification rates, individualized p.p.b.-range mass accuracies and proteome-wide protein quantification.

Recent advances in high-throughput cDNA sequencing (RNA-seq) can reveal new genes and splice variants and quantify expression genome-wide in a single assay. The volume and complexity of data from RNA-seq experiments necessitate scalable, fast and mathematically principled analysis software. TopHat and Cufflinks are free, open-source software tools for gene discovery and comprehensive expression analysis of high-throughput mRNA sequencing (RNA-seq) data. Together, they allow biologists to identify new genes and new splice variants of known ones, as well as compare gene and transcript expression under two or more conditions. This protocol describes in detail how to use TopHat and Cufflinks to perform such analyses. It also covers several accessory tools and utilities that aid in managing data, including CummeRbund, a tool for visualizing RNA-seq analysis results. Although the procedure assumes basic informatics skills, these tools assume little to no background with RNA-seq analysis and are meant for novices and experts alike. The protocol begins with raw sequencing reads and produces a transcriptome assembly, lists of differentially expressed and regulated genes and transcripts, and publication-quality visualizations of analysis results. The protocol's execution time depends on the volume of transcriptome sequencing data and available computing resources but takes less than 1 d of computer time for typical experiments and ∼1 h of hands-on time.

/pdf/differential-gene-and-transcript-expression-analysis-of-rna-3x9xt7iq01.pdf

Differential gene and transcript expression analysis of RNA-seq experiments with TopHat and Cufflinks

Gene expression is a multistep process that involves the transcription, translation and turnover of messenger RNAs and proteins. Although it is one of the most fundamental processes of life, the entire cascade has never been quantified on a genome-wide scale. Here we simultaneously measured absolute mRNA and protein abundance and turnover by parallel metabolic pulse labelling for more than 5,000 genes in mammalian cells. Whereas mRNA and protein levels correlated better than previously thought, corresponding half-lives showed no correlation. Using a quantitative model we have obtained the first genome-scale prediction of synthesis rates of mRNAs and proteins. We find that the cellular abundance of proteins is predominantly controlled at the level of translation. Genes with similar combinations of mRNA and protein stability shared functional properties, indicating that half-lives evolved under energetic and dynamic constraints. Quantitative information about all stages of gene expression provides a rich resource and helps to provide a greater understanding of the underlying design principles.

/pdf/global-quantification-of-mammalian-gene-expression-control-h9i2bar49f.pdf

Global quantification of mammalian gene expression control

A main bottleneck in proteomics is the downstream biological analysis of highly multivariate quantitative protein abundance data generated using mass-spectrometry-based analysis. We developed the Perseus software platform (http://www.perseus-framework.org) to support biological and biomedical researchers in interpreting protein quantification, interaction and post-translational modification data. Perseus contains a comprehensive portfolio of statistical tools for high-dimensional omics data analysis covering normalization, pattern recognition, time-series analysis, cross-omics comparisons and multiple-hypothesis testing. A machine learning module supports the classification and validation of patient groups for diagnosis and prognosis, and it also detects predictive protein signatures. Central to Perseus is a user-friendly, interactive workflow environment that provides complete documentation of computational methods used in a publication. All activities in Perseus are realized as plugins, and users can extend the software by programming their own, which can be shared through a plugin store. We anticipate that Perseus's arsenal of algorithms and its intuitive usability will empower interdisciplinary analysis of complex large data sets.

/pdf/the-perseus-computational-platform-for-comprehensive-5a4p3g7pp4.pdf

The Perseus computational platform for comprehensive analysis of (prote)omics data.

The plant-derived sesquiterpene lactone micheliolide was recently found to possess promising antileukemic activity, including the ability to target and kill leukemia stem cells. Efforts toward improving the biological activity of micheliolide and investigating its mechanism of action have been hindered by the paucity of preexisting functional groups amenable for late-stage derivatization of this molecule. Here, we report the implementation of a probe-based P450 fingerprinting strategy to rapidly evolve engineered P450 catalysts useful for the regio- and stereoselective hydroxylation of micheliolide at two previously inaccessible aliphatic positions in this complex natural product. Via P450-mediated chemoenzymatic synthesis, a broad panel of novel micheliolide analogs could thus be obtained to gain structure-activity insights into the effect of C2, C4, and C14 substitutions on the antileukemic activity of micheliolide, ultimately leading to the discovery of "micheliologs" with improved potency against acute myelogenic leukemia cells. These late-stage C-H functionalization routes could be further leveraged to generate a panel of affinity probes for conducting a comprehensive analysis of the protein targeting profile of micheliolide in leukemia cells via chemical proteomics analyses. These studies introduce new micheliolide-based antileukemic agents and shed new light onto the biomolecular targets and mechanism of action of micheliolide in leukemia cells. More broadly, this work showcases the value of the present P450-mediated C-H functionalization strategy for streamlining the late-stage diversification and elucidation of the biomolecular targets of a complex bioactive molecule.

Comprehensive Structure-Activity Profiling of Micheliolide and its Targeted Proteome in Leukemia Cells via Probe-Guided Late-Stage C-H Functionalization.

Prion diseases are a group of fatal neurodegenerative disorders caused by the misfolding of the cellular prion protein (PrPC) into a pathogenic conformation (PrPSc). PrPSc is capable of folding into multiple self-replicating prion strains that produce phenotypically distinct neurological disorders. Evidence suggests that the structural heterogeneity of PrPSc is the molecular basis of strain-specific prion properties. The self-templating of PrPSc typically ensures that prion strains breed true upon passage. However, prion strains also have the capacity to conformationally transform to maximize their rate of replication in a given environment. Here, we provide an overview of the prion-strain phenomenon and describe the role of strain adaptation in drug resistance. We also describe recent evidence that shows the presence of distinct conformational strains in other neurodegenerative disorders.

/pdf/biology-and-genetics-of-prp-prion-strains-2t011stapy.pdf

Biology and Genetics of PrP Prion Strains.

In proteomic research, it is often necessary to screen a large number of polypeptides for the presence of stable structure. Described herein are methods (referred to as MALDI MS-HX and SUPREX) for measuring the stability of proteins in a rapid, high-throughput fashion. The method employs hydrogen exchange to estimate the stability of quantities of unpurified protein extracts, using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. A method of quantitatively determining the stability of a test protein under native conditions is disclosed. The method includes the steps (a) providing a test protein; (b) contacting the protein with an exchange buffer comprising a denaturant and deuterium, the exchange buffer having a denaturant concentration; (c) contacting the test protein with a mass spectrometry matrix medium; (d) determining a change in mass of the test protein by mass spectrometry; (e) varying the denaturant concentration of the exchange buffer; (f) repeating steps (a)-(e) a desired number of times; and (g) quantitatively determining protein stability based on the change in mass of the test protein as a function of denaturant concentration, whereby the stability of a test protein under native conditions is quantitatively determined.

Quantitative, high-throughput screening method for protein stability

Aberrant expression of mitochondrial proteins impairs cardiac function and causes heart disease. The mechanism of regulation of mitochondria encoded protein expression during cardiac disease, however, remains underexplored. Here, we show that multiple pathogenic cardiac stressors induce the expression of miR-574 guide and passenger strands (miR-574-5p/3p) in both humans and mice. miR-574 knockout mice exhibit severe cardiac disorder under different pathogenic cardiac stresses while miR-574-5p/3p mimics that are delivered systematically using nanoparticles reduce cardiac pathogenesis under disease insults. Transcriptomic analysis of miR-574-null hearts uncovers family with sequence similarity 210 member A (FAM210A) as a common target mRNA of miR-574-5p and miR-574-3p. The interactome capture analysis suggests that FAM210A interacts with mitochondrial translation elongation factor EF-Tu. Manipulating miR-574-5p/3p or FAM210A expression changes the protein expression of mitochondrial-encoded electron transport chain (ETC) genes but not nuclear-encoded mitochondrial ETC genes in both human AC16 cardiomyocyte cells and miR-574-null murine hearts. Together, we discovered that miR-574 regulates FAM210A expression and modulates mitochondrial-encoded protein expression, which may influence cardiac remodeling in heart failure.

https://www.embopress.org/doi/pdf/10.15252/emmm.202012710

MicroRNA-574 regulates FAM210A expression and influences pathological cardiac remodeling.

Prion diseases are a group of fatal neurodegenerative diseases caused by the misfolding of cellular prion protein (PrP(C)) into pathogenic conformers (PrP(Sc)). Although no effective therapies for prion diseases are currently available, a number of small molecule inhibitors have been identified that are capable of reducing or eliminating PrP(Sc) in prion infected cells. However, recent experiments have shown that upon sustained treatment, prions have the capacity to evolve into drug resistant conformations. These studies suggest that the mechanism of prion strain adaptation involves rare conformational conversions followed by competitive selection among the heterogeneous pool of PrP(Sc) conformers. The plasticity of prion conformers makes PrP(Sc) a particularly challenging drug target and suggests that combination drug therapies or targeting of PrP(C) may be required for effective therapy. In this review, we highlight recent literature that demonstrate the phenomenon of prion drug resistance and strain specificity, and discuss potential ramifications for therapeutic efforts against prion diseases.

Sina Ghaemmaghami

Papers

Comprehensive Structure-Activity Profiling of Micheliolide and its Targeted Proteome in Leukemia Cells via Probe-Guided Late-Stage C-H Functionalization.

Biology and Genetics of PrP Prion Strains.

Quantitative, high-throughput screening method for protein stability

MicroRNA-574 regulates FAM210A expression and influences pathological cardiac remodeling.

Strain specificity and drug resistance in anti-prion therapy.