Protein phosphatase 2A and complement component 4 are linked to the protective effect of APOE ɛ2 for Alzheimer's disease.

INTRODUCTION: The apolipoprotein E (APOE) ɛ2 allele reduces risk against Alzheimer's disease (AD) but mechanisms underlying this effect are largely unknown. METHODS: We conducted a genome-wide association study for AD among 2096 ɛ2 carriers. The potential role of the top-ranked gene and complement 4 (C4) proteins, which were previously linked to AD in ɛ2 carriers, was investigated using human isogenic APOE allele-specific induced pluripotent stem cell (iPSC)-derived neurons and astrocytes and in 224 neuropathologically examined human brains. RESULTS: PPP2CB rs117296832 was the second most significantly associated single nucleotide polymorphism among ɛ2 carriers (P = 1.1 × 10-7 ) and the AD risk allele increased PPP2CB expression in blood (P = 6.6 × 10-27 ). PPP2CB expression was correlated with phosphorylated tau231/total tau ratio (P = .01) and expression of C4 protein subunits C4A/B (P = 2.0 × 10-4 ) in the iPSCs. PPP2CB (subunit of protein phosphatase 2A) and C4b protein levels were correlated in brain (P = 3.3 × 10-7 ). DISCUSSION: PP2A may be linked to classical complement activation leading to AD-related tau pathology.

Wnt pathway-related three-mRNA clinical outcome signature in bladder urothelial carcinoma: computational biology and experimental analyses.

BACKGROUND: The Wnt signaling pathway is core to the growth of bladder tumors. Epithelial-to-mesenchymal transition (EMT) is significant for bladder tumor metastasis. Nevertheless, the relationship between the Wnt signaling pathway, outcomes of bladder cancer (BLCA), and the specific mechanisms driving immune infiltration have not been studied. METHODS: We obtained Wnt pathway-related gene mRNA and clinicopathological data from the Cancer Genome Atlas (TCGA). We obtained 34 genes that were greatly correlated with outcome using univariate Cox regression analysis and conducted a completely randomized data t-test to perform clinical staging. According to the single-sample gene set enrichment analysis (ssGSEA), the weighted correlation network analysis (WGCNA) was applied to identify relevant biological functions. Various subtypes were identified using consensus cluster analysis. Univariate Cox regression and least absolute shrinkage sum selection operator-Cox regression algorithm analysis were conducted on TCGA and Gene Expression Omnibus data to identify risk characteristics. The Kaplan-Meier method and receiver running feature curves were adopted to calculate overall survival. Single-sample gene set enrichment analysis (ssGSEA) was adopted for the assessment of the degree of immune infiltration. Then, we demonstrated the relationship between PPP2CB and EMT function in two cell lines. RESULTS: Thirty-four Wnt signaling pathway-related genes were risk factors for BLCA outcome, and their expression levels differed by clinical stage. The co-expression of WGCNA showed the relationship between the Wnt signaling pathway and biological functions and was closely associated with EMT. We divided BLCA patients into two subtypes using consensus clustering. Survival curves and clinical analysis showed that the Wnt pathway enriched group had worse outcomes. The Wnt signature showed the significance of the outcome for MAPK10, PPP2CB, and RAC3. Based on these genes, the degree of immune infiltration was evaluated. Cell function experiments suggested that PPP2CB drives the proliferation and migration of BLCA cells. CONCLUSION: We found that Wnt signaling pathway-related genes can be used as prognostic risk factors for BLCA, and the Wnt signaling pathway is a cancer-promoting signaling pathway associated with EMT. We identified three critical genes: MAPK10, RAC3, and PPP2CB. The genes in these three Wnt signaling pathways are associated with tumor cell EMT and immune cell infiltration. The most important finding was that these three genes were independent prognostic factors for BLCA.

Proteomic Maps of Human Gastrointestinal Stromal Tumor Subgroups.

Gastrointestinal stromal tumor (GIST) is a common sarcoma of gastrointestinal tract (GIT) with high metastatic and recurrence rates, but the proteomic features are still less understood. Here we performed systematic quantitative proteome profiling of GIST from 13 patients classified into very low/low, intermediate and high risk subgroups. An extended cohort of GIST (n = 131) was used for immunohistochemical validation of proteins of interest. In total, 9177 proteins were quantified, covering 55.9% of the GIT transcriptome from The Human Protein Altas. Out of the 9177 quantified proteins, 4930 proteins were observed in all 13 cases with 517 upregulated and 187 downregulated proteins in tumorous tissues independent of risk stage. Pathway analysis showed that the downregulated proteins were mostly enriched in metabolic pathway, whereas the upregulated proteins mainly belonged to spliceosome pathway. In addition, 131 proteins showed differentially expressed patterns among GIST subgroups with statistical significance. The 13 GIST cases were classified into 3 subgroups perfectly based on the expression of these proteins. The intensive comparison of molecular phenotypes and possible functions of quantified oncoproteins, tumor suppressors, phosphatases and kinases between GIST subgroups was carried out. Immunohistochemical analysis of the phosphatase PTPN1 (n = 117) revealed that the GIST patients with high PTPN1 expression had low chances of developing metastasis. Collectively, this work provides valuable information for understanding the inherent biology and evolution of GIST.

Dynamic Phosphorylation of G9a Regulates its Repressive Activity on Chromatin Accessibility and Mitotic Progression.

Phosphorylation of Ser10 of histone H3 (H3S10p), together with the adjacent methylation of Lys9 (H3K9me), has been proposed to function as a 'phospho-methyl switch' to regulate mitotic chromatin architecture. Despite of immense understanding of the roles of H3S10 phosphorylation, how H3K9me2 are dynamically regulated during mitosis is poorly understood. Here, it is identified that Plk1 kinase phosphorylates the H3K9me1/2 methyltransferase G9a/EHMT2 at Thr1045 (pT1045) during early mitosis, which attenuates its catalytic activity toward H3K9me2. Cells bearing Thr1045 phosphomimic mutant of G9a (T1045E) show decreased H3K9me2 levels, increased chromatin accessibility, and delayed mitotic progression. By contrast, dephosphorylation of pT1045 during late mitosis by the protein phosphatase PPP2CB reactivates G9a activity and upregulates H3K9me2 levels, correlated with decreased levels of H3S10p. Therefore, the results provide a mechanistic explanation of the essential of a 'phospho-methyl switch' and highlight the importance of Plk1 and PPP2CB-mediated dynamic regulation of G9a activity in chromatin organization and mitotic progression.

Protein phosphatase 2A catalytic subunit ß suppresses PMA/ionomycin-induced T-cell activation by negatively regulating PI3K/Akt signaling.

The precise regulation of the T-cell activation process is critical for overall immune homeostasis. Although protein phosphatase 2A (PP2A) is required for T-cell development and function, the role of PPP2CB, which is the catalytic subunit ß isoform of PP2A, remains unknown. In the present study, using a T cell-specific knockout mouse of PPP2CB (PPP2CBfl/fl Lck-Cre+ ), we demonstrated that PPP2CB was dispensable for T-cell development in the thymus and peripheral lymphoid organs. Furthermore, PPP2CB deletion did not affect T-cell receptor (TCR)-induced T-cell activation or cytokine-induced T-cell responses; however, it specifically enhanced phorbol myristate acetate (PMA) plus ionomycin-induced T-cell activation with increased cellular proliferation, elevated CD69 and CD25 expression, and enhanced cytokine production (inteferon-γ, interleukin-2 and tumor necrosis factor). Mechanistic analyses suggested that the PPP2CB deletion enhanced activation of the phosphoinositide 3-kinase/Akt signaling pathway and Ca2+ flux following stimulation with PMA plus ionomycin. Moreover, the specific PI3K inhibitor rescued the augmented cell activation in PPP2CB-deficient T cells. Using mass spectrometry-based phospho-peptide analysis, we identified potential substrates of PPP2CB during PMA plus ionomycin-induced T-cell activation. Collectively, our study provides evidence of the specific role of PPP2CB in controlling PMA plus ionomycin-induced T-cell activation.

Novel Y Chromosome Retrocopies in Canids Revealed through a Genome-Wide Association Study for Sex.

The lack of an annotated reference sequence for the canine Y chromosome has limited evolutionary studies, as well as our understanding of the role of Y-linked sequences in phenotypes with a sex bias. In genome-wide association studies (GWASs), we observed spurious associations with autosomal SNPs when sex was unbalanced in case-control cohorts and hypothesized that a subset of SNPs mapped to autosomes are in fact sex-linked. Using the Illumina 230K CanineHD array in a GWAS for sex, we identified SNPs that amplify in both sexes but possess significant allele frequency differences between males and females. We found 48 SNPs mapping to 14 regions of eight autosomes and the X chromosome that are Y-linked, appearing heterozygous in males and monomorphic in females. Within these 14 regions are eight genes: three autosomal and five X-linked. We investigated the autosomal genes (MITF, PPP2CB, and WNK1) and determined that the SNPs are diverged nucleotides in retrocopies that have transposed to the Y chromosome. MITFY and WNK1Y are expressed and appeared recently in the Canidae lineage, whereas PPP2CBY represents a much older insertion with no evidence of expression in the dog. This work reveals novel canid Y chromosome sequences and provides evidence for gene transposition to the Y from autosomes and the X.

MRNA and miRNA expression patterns associated to pathways linked to metal mixture health effects.

Metals are a threat to human health by increasing disease risk. Experimental data have linked altered miRNA expression with exposure to some metals. MiRNAs comprise a large family of non-coding single-stranded molecules that primarily function to negatively regulate gene expression post-transcriptionally. Although several human populations are exposed to low concentrations of As, Cd and Pb as a mixture, most toxicology research focuses on the individual effects that these metals exert. Thus, this study aims to evaluate global miRNA and mRNA expression changes induced by a metal mixture containing NaAsO2, CdCl2, Pb(C2H3O2)2·3H2O and to predict possible metal-associated disease development under these conditions. Our results show that this metal mixture results in a miRNA expression profile that may be responsible for the mRNA expression changes observed under experimental conditions in which coding proteins are involved in cellular processes, including cell death, growth and proliferation related to the metal-associated inflammatory response and cancer.