Inflammatory T cells contribute to the pathogenesis of autoimmune diseases such as systemic lupus erythematosus (SLE). Analysis of the T-cell transcriptomics data of two independent SLE patient cohorts by three machine learning models revealed the pseudogene UHRF1P as a novel SLE biomarker. The pseudogene-encoded UHRF1P protein was overexpressed in peripheral blood T cells of SLE patients. The UHRF1P protein lacks the amino-terminus of its parental UHRF1 protein, resulting in missing the proteasome-binding ubiquitin-like (Ubl) domain of UHRF1. T-cell-specific UHRF1P transgenic mice manifested the induction of IL-17A and autoimmune inflammation. Mechanistically, UHFR1P prevented UHRF1-induced Lys48-linked ubiquitination and degradation of MAP4K3 (GLK), which is a kinase known to induce IL-17A. Consistently, IL-17A induction and autoimmune phenotypes of UHRF1P transgenic mice were obliterated by MAP4K3 knockout. Collectively, UHRF1P overexpression in T cells inhibits the E3 ligase function of its parental UHRF1 and induces autoimmune diseases.
CCAAT-Enhancer-Binding Proteins , Interleukin-17 , Lupus Erythematosus, Systemic , Mice, Transgenic , Protein Serine-Threonine Kinases , Ubiquitin-Protein Ligases , Lupus Erythematosus, Systemic/immunology , Lupus Erythematosus, Systemic/genetics , Lupus Erythematosus, Systemic/metabolism , Animals , Interleukin-17/metabolism , Interleukin-17/genetics , Ubiquitin-Protein Ligases/genetics , Ubiquitin-Protein Ligases/metabolism , Humans , Mice , CCAAT-Enhancer-Binding Proteins/metabolism , CCAAT-Enhancer-Binding Proteins/genetics , Protein Serine-Threonine Kinases/metabolism , Protein Serine-Threonine Kinases/genetics , Ubiquitination , Mice, Knockout , Disease Models, Animal , Signal Transduction , T-Lymphocytes/immunology , T-Lymphocytes/metabolism , Autoimmunity , Female
The results of conventional gene-based analyses which combine epigenome and transcriptome data, including those conducted by the ENCODE/modENCODE projects, suggest various histone modifications performing regulatory functions in controlling mRNA expression (referred to as a histone code) in several model animals. While some histone codes were found to be universally adopted across organisms, "species-specific" histone codes have also been defined. We found that the characterization of these histone codes was confounded by factors (e.g. gene essentiality, expression breadth) that are independent of, but correlated with, gene expression levels. Hence, we attempted to decode histone marks in mouse (Mus musculus), fly (Drosophila melanogaster), and worm (Caenorhabditis elegans) genomes by examining ratios of RNA sequencing (and chromatin immunoprecipitation sequencing) intensities between paralog genes to remove confounding effects that would otherwise be present in a gene-based approach. With this paralog-based approach, associations between four histone modifications (H3K4me3, H3K27ac, H3K9ac, and H3K36me3) and gene expression are substantially revised. For example, we demonstrate that H3K27ac and H3K9ac represent universal active marks in promoters, rather than worm-specific marks as previously reported. Second, acting regions of the studied active marks that are common across species (and across a wide range of tissues at different developmental stages) were found to extend beyond the previously defined regions. Thus, it appears that the active histone codes analyzed have a universality that has previously been underappreciated. Our results suggested that these universal codes, including those previously considered species-specific, could have an ancient origin, and are important in regulating animal gene expression abundance.
