AKT-dependent nuclear localization of EPRS1 activates PARP1 in breast cancer cells.

Glutamyl-prolyl-tRNA synthetase (EPRS1) is a bifunctional aminoacyl-tRNA-synthetase (aaRS) essential for decoding the genetic code. EPRS1 resides, with seven other aaRSs and three noncatalytic proteins, in the cytoplasmic multi-tRNA synthetase complex (MSC). Multiple MSC-resident aaRSs, including EPRS1, exhibit stimulus-dependent release from the MSC to perform noncanonical activities distinct from their primary function in protein synthesis.

Cell surface CD55 traffics to the nucleus leading to cisplatin resistance and stemness by inducing PRC2 and H3K27 trimethylation on chromatin in ovarian cancer.

Background: Platinum resistance is the primary cause of poor survival in ovarian cancer (OC) patients. Targeted therapies and biomarkers of chemoresistance are critical for the treatment of OC patients. Our previous studies identified cell surface CD55, a member of the complement regulatory proteins, drives chemoresistance and maintenance of cancer stem cells (CSCs).

Homozygous EPRS1 missense variant causing hypomyelinating leukodystrophy-15 alters variant-distal mRNA mA site accessibility.

Hypomyelinating leukodystrophy (HLD) is an autosomal recessive disorder characterized by defective central nervous system myelination. Exome sequencing of two siblings with severe cognitive and motor impairment and progressive hypomyelination characteristic of HLD revealed homozygosity for a missense single-nucleotide variant (SNV) in EPRS1 (c.4444 C > A; p.

Host-like RNA Elements Regulate Virus Translation.

Viruses are obligate, intracellular parasites that co-opt host cell machineries for propagation. Critical among these machineries are those that translate RNA into protein and their mechanisms of control. Most regulatory mechanisms effectuate their activity by targeting sequence or structural features at the RNA termini, i.

Homeostatic iron regulatory protein drives glioblastoma growth via tumor cell-intrinsic and sex-specific responses.

Background: Glioblastoma (GBM) displays alterations in iron that drive proliferation and tumor growth. Iron regulation is complex and involves many regulatory mechanisms, including the homeostatic iron regulator () gene, which encodes the homeostatic iron regulatory protein. While is upregulated in GBM and correlates with poor survival outcomes, the function of HFE in GBM remains unclear.

Aminoacyl-tRNA synthetase interactions in SARS-CoV-2 infection.

Aminoacyl-tRNA synthetases (aaRSs) are ancient enzymes that serve a foundational role in the efficient and accurate translation of genetic information from messenger RNA to proteins. These proteins play critical, non-canonical functions in a multitude of cellular processes. Multiple viruses are known to hijack the functions of aaRSs for proviral outcomes, while cells modify antiviral responses through non-canonical functions of certain synthetases.

Translational control of murine adiponectin expression by an upstream open reading frame element.

Adiponectin, an adipocyte-specific secretory protein encoded by the gene has a causal role in insulin resistance. Anti-diabetic drugs increase plasma adiponectin by a poorly understood, post-transcriptional mechanism enhancing insulin sensitivity. Deletion analysis of a reporter bearing the mouse mRNA 5'-leader identified an inhibitory -regulatory sequence.

Benefits of co-translational complex assembly for cellular fitness.

Complexes of two or more proteins form many, if not most, of the intracellular "machines" that execute physical and chemical work, and transmit information. Complexes can form from stochastic post-translational interactions of fully formed proteins, but recent attention has shifted to co-translational interactions in which the most common mechanism involves binding of a mature constituent to an incomplete polypeptide emerging from a translating ribosome. Studies in yeast have revealed co-translational interactions during formation of multiple major complexes, and together with recent mammalian cell studies, suggest widespread utilization of the mechanism.

Glutamyl-prolyl-tRNA synthetase 1 coordinates early endosomal anti-inflammatory AKT signaling.

The AKT signaling pathway plays critical roles in the resolution of inflammation. However, the underlying mechanisms of anti-inflammatory regulation and signal coordination remain unclear. Here, we report that anti-inflammatory AKT signaling is coordinated by glutamyl-prolyl-tRNA synthetase 1 (EPRS1).

Analysis of nested alternate open reading frames and their encoded proteins.

Transcriptional and post-transcriptional mechanisms diversify the proteome beyond gene number, while maintaining a sequence relationship between original and altered proteins. A new mechanism breaks this paradigm, generating novel proteins by translating alternative open reading frames (Alt-ORFs) within canonical host mRNAs. Uniquely, 'alt-proteins' lack sequence homology with host ORF-derived proteins.

Multimodal cotranslational interactions direct assembly of the human multi-tRNA synthetase complex.

Amino acid ligation to cognate transfer RNAs (tRNAs) is catalyzed by aminoacyl-tRNA synthetases (aaRSs)-essential interpreters of the genetic code during translation. Mammalian cells harbor 20 cytoplasmic aaRSs, out of which 9 (in 8 proteins), with 3 non-aaRS proteins, AIMPs 1 to 3, form the ∼1.25-MDa multi-tRNA synthetase complex (MSC).

IL-17-induced HIF1α drives resistance to anti-PD-L1 via fibroblast-mediated immune exclusion.

Increasing evidence suggests that intratumoral inflammation has an outsized influence on antitumor immunity. Here, we report that IL-17, a proinflammatory cytokine widely associated with poor prognosis in solid tumors, drives the therapeutic failure of anti-PD-L1. By timing the deletion of IL-17 signaling specifically in cancer-associated fibroblasts (CAFs) in late-stage tumors, we show that IL-17 signaling drives immune exclusion by activating a collagen deposition program in murine models of cutaneous squamous cell carcinoma (cSCC).

An optimized protocol for and structural determination of the multi-tRNA synthetase complex by cross-linking mass spectrometry.

Despite recent advances in structural determination of individual proteins, elucidating the 3-dimensional architecture of large, multiprotein complexes remains challenging, partly because of issues related to structural integrity during purification. Here, we describe a protocol to determine the 3-dimensional architecture of the 11-constituent, multi-tRNA synthetase complex (MSC) using chemical cross-linking coupled with mass-spectrometry (XL-MS). The protocol does not require purification and is broadly applicable, facilitating determination of native structures in cell lysates and in non-disrupted cells as well as in purified complexes.

Aminoacyl-tRNA synthetases of the multi-tRNA synthetase complex and their role in tumorigenesis.

In mammalian cells, 20 aminoacyl-tRNA synthetases (AARS) catalyze the ligation of amino acids to their cognate tRNAs to generate aminoacylated-tRNAs. In higher eukaryotes, 9 of the 20 AARSs, along with 3 auxiliary proteins, join to form the cytoplasmic multi-tRNA synthetase complex (MSC). The complex is absent in prokaryotes, but evolutionary expansion of MSC constituents, primarily by addition of novel interacting domains, facilitates formation of subcomplexes that join to establish the holo-MSC.

Cotranslational interaction of human EBP50 and ezrin overcomes masked binding site during complex assembly.

Multiprotein assemblages are the intracellular workhorses of many physiological processes. Assembly of constituents into complexes can be driven by stochastic, domain-dependent, posttranslational events in which mature, folded proteins specifically interact. However, inaccessibility of interacting surfaces in mature proteins (e.

Screening of CRISPR-Cas9-generated point mutant mice using MiSeq and locked nucleic acid probe PCR.

CRISPR-Cas9-mediated, site-directed mutagenesis in mice generates mosaic founder mice with varied efficiency of desired point mutation and other non-homologous end-joined variants. Here, we present a protocol for design, sample preparation, and analysis for identification of mice with the desired mutation. Deep sequencing provides the proportion of reads of a particular allele for each mouse line.

The zinc-binding domain of mammalian prolyl-tRNA synthetase is indispensable for catalytic activity and organism viability.

Aminoacyl-tRNA synthetases (AARS) participate in decoding the genome by catalyzing conjugation of amino acids to their cognate tRNAs. During evolution, biochemical and environmental conditions markedly influenced the sequence and structure of the 20 AARSs, revealing adaptations dictating canonical and orthogonal activities. Here, we investigate the function of the appended Zn-binding domain (ZBD) in the bifunctional AARS, glutamyl-prolyl-tRNA synthetase (GluProRS).

Bidirectional Tumor-Promoting Activities of Macrophage Ezrin.

Ezrin links the cytoskeleton to cell surface integrins and plasma membrane receptors, contributing to the proliferative and metastatic potential of cancer cells. Elevated ezrin expression in several cancers is associated with poor outcomes. Tumor cell ezrin expression and function have been investigated in depth; however, its role in macrophages and other tumor microenvironment cells remains unexplored.

IL-1 induces mitochondrial translocation of IRAK2 to suppress oxidative metabolism in adipocytes.

Chronic inflammation is a common feature of obesity, with elevated cytokines such as interleukin-1 (IL-1) in the circulation and tissues. Here, we report an unconventional IL-1R-MyD88-IRAK2-PHB/OPA1 signaling axis that reprograms mitochondrial metabolism in adipocytes to exacerbate obesity. IL-1 induced recruitment of IRAK2 Myddosome to mitochondria outer membranes via recognition by TOM20, followed by TIMM50-guided translocation of IRAK2 into mitochondria inner membranes, to suppress oxidative phosphorylation and fatty acid oxidation, thereby attenuating energy expenditure.

3-Dimensional architecture of the human multi-tRNA synthetase complex.

In mammalian cells, eight cytoplasmic aminoacyl-tRNA synthetases (AARS), and three non-synthetase proteins, reside in a large multi-tRNA synthetase complex (MSC). AARSs have critical roles in interpretation of the genetic code during protein synthesis, and in non-canonical functions unrelated to translation. Nonetheless, the structure and function of the MSC remain unclear.

Protein S-Nitrosylation of Human Cytomegalovirus pp71 Inhibits Its Ability To Limit STING Antiviral Responses.

Human (HCMV) is a ubiquitous pathogen that has coevolved with its host and, in doing so, is highly efficient in undermining antiviral responses that limit successful infections. As a result, HCMV infections are highly problematic in individuals with weakened or underdeveloped immune systems, including transplant recipients and newborns. Understanding how HCMV controls the microenvironment of an infected cell so as to favor productive replication is of critical importance.

Inflammation mobilizes copper metabolism to promote colon tumorigenesis via an IL-17-STEAP4-XIAP axis.

Copper levels are known to be elevated in inflamed and malignant tissues. But the mechanism underlying this selective enrichment has been elusive. In this study, we report a axis by which inflammatory cytokines, such as IL-17, drive cellular copper uptake via the induction of a metalloreductase, STEAP4.

Selective deletion of MyD88 signaling in α-SMA positive cells ameliorates experimental intestinal fibrosis via post-transcriptional regulation.

Intestinal fibrosis leading to strictures remains a significant clinical problem in inflammatory bowel diseases (IBD). The role of bacterial components in activating intestinal mesenchymal cells and driving fibrogenesis is largely unexplored. Tamoxifen-inducible α-SMA promoter Cre mice crossed with floxed MyD88 mice were subjected to chronic dextran sodium sulfate colitis.