Innate immune sensor laboratory of genetics and physiology 2 suppresses tumor cell growth and functions as a prognostic marker in neuroblastoma

Friend or foe: RIG- I like receptors and diseases

Retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs), which are pivotal sensors of RNA virus invasions, mediate the transcriptional induction of genes encoding type I interferons (IFNs) and proinflammatory cytokines, successfully establishing host antiviral immune response. A few excellent reviews have elaborated on the structural biology of RLRs and the antiviral mechanisms of RLR activation. In this review, we give a basic understanding of RLR biology and summarize recent findings of how RLR signaling cascade is strictly controlled by host regulatory mechanisms, which include RLR-interacting proteins, post-translational modifications and microRNAs (miRNAs). Furthermore, we pay particular attention to the relationship between RLRs and diseases, especially how RLRs participate in SARS-CoV-2, malaria or bacterial infections, how single-nucleotide polymorphisms (SNPs) or mutations in RLRs and antibodies against RLRs lead to autoinflammatory diseases and autoimmune diseases, and how RLRs are involved in anti-tumor immunity. These findings will provide insights and guidance for antiviral and immunomodulatory therapies targeting RLRs.

Emerging role of RNA sensors in tumor microenvironment and immunotherapy

RNA sensors detect foreign and endogenous RNAs to protect the host by initiating innate and adaptive immune response. In tumor microenvironment (TME), activation of RNA sensors induces tumor-inhibitory cytotoxic T lymphocyte responses and inhibits the activity of immunosuppressive cells though stimulating type I IFN signaling pathway. These characteristics allow RNA sensors to be prospective targets in tumor immunotherapy. Therefore, a comprehensive understanding of the roles of RNA sensors in TME could provide new insight into the antitumor immunotherapy. Moreover, RNA sensors could be prominent triggering targets to synergize with immunotherapies. In this review, we highlight the diverse mechanisms of RNA sensors in cancer immunity and their emerging contributions in cancer immunotherapy, including monotherapy with RNA sensor agonists, as well as combination with chemotherapy, radiotherapy, immune checkpoint blockade or cancer vaccine.

Inflammation-Related Risk Loci in Genome-Wide Association Studies of Coronary Artery Disease

Although the importance of inflammation in atherosclerosis is now well established, the exact molecular processes linking inflammation to the development and course of the disease are not sufficiently understood. In this context, modern genetics—as applied by genome-wide association studies (GWAS)—can serve as a comprehensive and unbiased tool for the screening of potentially involved pathways. Indeed, a considerable proportion of loci discovered by GWAS is assumed to affect inflammatory processes. Despite many well-replicated association findings, however, translating genomic hits to specific molecular mechanisms remains challenging. This review provides an overview of the currently most relevant inflammation-related GWAS findings in coronary artery disease and explores their potential clinical perspectives.

LGP2 virus sensor enhances apoptosis by upregulating apoptosis regulatory genes through TRBP-bound miRNAs during viral infection

During viral infection, viral nucleic acids are detected by virus sensor proteins including toll-like receptor 3 or retinoic acid-inducible gene I-like receptors (RLRs) in mammalian cells. Activation of these virus sensor proteins induces type-I interferon production and represses viral replication. Recently, we reported that an RLR family member, laboratory of genetics and physiology 2 (LGP2), modulates RNA silencing by interacting with an RNA silencing enhancer, TAR-RNA binding protein (TRBP). However, the biological implications remained unclear. Here, we show that LGP2 enhances apoptosis by upregulating apoptosis regulatory genes during viral infection. Sendai virus (SeV) infection increased LGP2 expression approximately 900 times compared to that in non-virus-infected cells. Then, the induced LGP2 interacted with TRBP, resulting in the inhibition of maturation of the TRBP-bound microRNA (miRNA) and its subsequent RNA silencing activity. Gene expression profiling revealed that apoptosis regulatory genes were upregulated during SeV infection: caspases-2, -8, -3 and -7, four cysteine proteases with key roles in apoptosis, were upregulated directly or indirectly through the repression of a typical TRBP-bound miRNA, miR-106b. Our findings may shed light on the mechanism of apoptosis, induced by the TRBP-bound miRNAs through the interaction of TRBP with LGP2, as an antiviral defense system in mammalian cells.

Innate immune sensor laboratory of genetics and physiology 2 suppresses tumor cell growth and functions as a prognostic marker in neuroblastoma

The innate immune receptors, such as toll-like receptor 3 (TLR3), melanoma differentiation-associated 5 (MDA5) and retinoic acid-inducible gene-I (RIG-I), have been shown to be differentially expressed in neuroblastoma (NB) and promote dsRNA poly (I:C)-induced NB suppression in vitro and in vivo. However, the role of another important innate immune cytosolic sensor, laboratory of genetics and physiology 2 (LGP2), in the cancer behavior of NB remains unclear. Here, we demonstrated that the expression levels of LGP2 were either low or undetectable in all NB cell lines tested with or without MYCN amplification. LGP2 expression levels were significantly increased only in NB cells without MYCN amplification, including SK-N-AS and SK-N-FI after poly (I:C) treatment in vitro and in mouse xenograft models. Ectopic expression of LGP2 in NB cells significantly enhanced poly (I:C)-induced NB cell death associated with downregulation of MDA5, RIG-I, MAVS and Bcl-2, as well as upregulation of Noxa and tBid. By immunofluorescence analyses, LGP2 localized mainly in the cytoplasm of NB cells after poly (I:C) treatment. In human NB tissue samples, cytoplasmic LGP2 expression was positively correlated with histological differentiation and inversely correlated with MYCN amplification. Positive cytoplasmic LGP2 expression in tumor tissues could predict a favorable outcome in NB patients independent of other prognostic factors. In short, LGP2 was effective in promoting poly (I:C)-induced NB suppression and cytoplasmic LGP2 can serve as an independent favorable prognostic factor in NB patients.