A DNA adjuvant encoding a fusion protein between anti-CD3 single-chain Fv and AIMP1 enhances T helper type 1 cell-mediated immune responses in antigen-sensitized mice

The mARS complex: a critical mediator of immune regulation and homeostasis

Over the course of evolution, many proteins have undergone adaptive structural changes to meet the increasing homeostatic regulatory demands of multicellularity. Aminoacyl tRNA synthetases (aaRS), enzymes that catalyze the attachment of each amino acid to its cognate tRNA, are such proteins that have acquired new domains and motifs that enable non-canonical functions. Through these new domains and motifs, aaRS can assemble into large, multi-subunit complexes that enhance the efficiency of many biological functions. Moreover, because the complexity of multi-aminoacyl tRNA synthetase (mARS) complexes increases with the corresponding complexity of higher eukaryotes, a contribution to regulation of homeostatic functions in multicellular organisms is hypothesized. While mARS complexes in lower eukaryotes may enhance efficiency of aminoacylation, little evidence exists to support a similar role in chordates or other higher eukaryotes. Rather, mARS complexes are reported to regulate multiple and variegated cellular processes that include angiogenesis, apoptosis, inflammation, anaphylaxis, and metabolism. Because all such processes are critical components of immune homeostasis, it is important to understand the role of mARS complexes in immune regulation. Here we provide a conceptual analysis of the current understanding of mARS complex dynamics and emerging mARS complex roles in immune regulation, the increased understanding of which should reveal therapeutic targets in immunity and immune-mediated disease.

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. In some cases, environmental cues direct the release of constituents from the MSC which enables the execution of non-canonical, i.e., "moonlighting", functions distinct from their essential activities in protein translation. These activities are generally beneficial, but can also be deleterious to the cell. Elucidation of the non-canonical activities of several AARSs residing in the MSC suggest they are potential therapeutic targets for cancer, as well as metabolic and neurologic diseases. Here, we describe the role of MSC-resident AARSs in cancer progression, and the factors that regulate their release from the MSC. Also, we highlight recent developments in therapeutic modalities that target MSC AARSs for cancer prevention and treatment.

Extracellular activities of aminoacyl-tRNA synthetases: new mediators for cell-cell communication

Over the last decade, many reports have discussed aminoacyl-tRNA synthetases (ARSs) in extracellular space. Now that so many of them are known to be secreted with distinct activities in the broad range of target cells including endothelial, various immune cells, and fibroblasts, they need to be classified as a new family of extracellular signal mediators. In this chapter the identity of the secreted ARSs, receptors, and their physiological and pathological implications will be described.

Association of aminoacyl-tRNA synthetases with cancer

Although aminoacyl-tRNA synthetases (ARSs) and ARS-interacting multi-functional proteins (AIMPs) have long been recognized as housekeeping proteins, evidence indicating that they play a key role in regulating cancer is now accumulating. In this chapter we will review the conventional and non-conventional functions of ARSs and AIMPs with respect to carcinogenesis. First, we will address how ARSs and AIMPs are altered in terms of expression, mutation, splicing, and post-translational modifications. Second, the molecular mechanisms for ARSs' and AIMPs' involvement in the initiation, maintenance, and progress of carcinogenesis will be covered. Finally, we will introduce the development of therapeutic approaches that target ARSs and AIMPs with the goal of treating cancer.