Retinoic acid-inducible gene I (RIG-I) is an intracellular RNA virus sensor that induces type I interferon-mediated host-protective innate immunity against viral infection. Although cylindromatosis (CYLD) has been shown to negatively regulate innate antiviral response by removing K-63-linked polyubiquitin from RIG-I, the regulation of its expression and the underlying regulatory mechanisms are still incompletely understood. Here we show that RIG-I activity is regulated by inhibition of CYLD expression mediated by the microRNA miR-526a. We found that viral infection specifically upregulates miR-526a expression in macrophages via interferon regulatory factor (IRF)-dependent mechanisms. In turn, miR-526a positively regulates virus-triggered type I interferon (IFN-I) production, thus suppressing viral replication, the underlying mechanism of which is the enhancement of RIG-I K63-linked ubiquitination by miR-526a via suppression of the expression of CYLD. Remarkably, virusinduced miR-526a upregulation and CYLD downregulation are blocked by enterovirus 71 (EV71) 3C protein, while ectopic miR526a expression inhibits the replication of EV71 virus. The collective results of this study suggest a novel mechanism of the regulation of RIG-I activity during RNA virus infection by miR-526a and suggest a novel mechanism for the evasion of the innate immune response controlled by EV71. IMPORTANCERNA virus infection upregulates the expression of miR-526a in macrophages through IRF-dependent pathways. In turn, miR526a positively regulates virus-triggered type I IFN production and inhibits viral replication, the underlying mechanism of which is the enhancement of RIG-I K-63 ubiquitination by miR-526a via suppression of the expression of CYLD. Remarkably, virus-induced miR-526a upregulation and CYLD downregulation are blocked by enterovirus 71 (EV71) 3C protein; cells with overexpressed miR-526a were highly resistant to EV71 infection. The collective results of this study suggest a novel mechanism of the regulation of RIG-I activity during RNA virus infection by miR-526a and propose a novel mechanism for the evasion of the innate immune response controlled by EV71.

The first two-photon probe, Lyso-OC, was proposed for use in monitoring cell autophagy by detection of the change in the lysosomal polarity during the membrane fusion process of autophagy. The Lyso-OC probe exhibited desirable optical properties and a detection signal that was selective to the polarity change. More importantly, Lyso-OC displayed real-time monitoring of autophagy in living cells.

Resistance to antiestrogens is one of the major challenges in breast cancer treatment. Although phosphorylation of estrogen receptor α (ERα) is an important factor in endocrine resistance, the contributions of specific kinases in endocrine resistance are still not fully understood. Here, we report that an important innate immune response kinase, the IκB kinase-related TANK-binding kinase 1 (TBK1), is a crucial determinant of resistance to tamoxifen therapies. We show that TBK1 increases ERα transcriptional activity through phosphorylation modification of ERα at the Ser-305 site. Ectopic TBK1 expression impairs the responsiveness of breast cancer cells to tamoxifen. By studying the specimens from patients with breast cancer, we find a strong positive correlation of TBK1 with ERα, ERα Ser-305, and cyclin D1. Notably, patients with tumors highly expressing TBK1 respond poorly to tamoxifen treatment and show high potential for relapse. Therefore, our findings suggest that TBK1 contributes to tamoxifen resistance in breast cancer via phosphorylation modification of ERα.T ANK-binding kinase 1 (TBK1) and IκB kinase e (IKKe) are two IKK-related serine/threonine kinases that display 64% sequence identity and trigger the antiviral response of interferons (IFN) through NF-κB activation and interferon regulatory transcription factor (IRF) 3/7 phosphorylation (1-3). In addition to the proposed roles of IKK-related kinases in controlling transcription factors NF-κB and IRF, the involvement of TBK1 and IKKe in AKT-induced oncogenic transformation has been demonstrated in a recent study (4). TBK1 is identified as a Raslike (Ral) B effector in the Ral guanine nucleotide exchange factor pathway that is required for Ras-induced transformation (5). IKKe acts downstream of the PI3K-AKT pathway and cooperates with activated MEK to promote cellular transformation (6). IKKe has also been identified recently as a breast cancer oncogene that is frequently amplified or overexpressed in human breast cancer, and the phosphorylation of ERα by IKKe contributes to tamoxifen resistance in breast cancer (7-9). Interestingly, TBK1 is also highly expressed in breast cancer (10), and knocking down TBK1 diminishes the viability of MCF-7 cells (9). However, the exact role of TBK1 in breast cancer remains unclear.Estrogen receptor α (ERα) is a nuclear receptor that exerts a profound influence on the initiation and progression of breast cancer by regulating cell transformation, proliferation, and metastasis (11-13). For ERα-positive patients with breast cancer, targeting the ER signaling pathway with tamoxifen, a selective ER modulator, is efficacious in both prevention and treatment of breast cancer (14). Unfortunately, a substantial proportion of patients are intrinsically resistant to this therapy, and a significant number of patients with advanced disease eventually develop acquired resistance to the treatment (15-18). ERα is a key determinant of breast cancer susceptibility to endocrine therapy. Recent studies demonstrate that ERα phosphorylation ...

The mitochondrial antiviral signaling protein MAVS (IPS-1, VISA, or Cardif) plays an important role in the host defense against viral infection by inducing type I interferon. Recent reports have shown that MAVS is also critical for virus-induced apoptosis. However, the mechanism of MAVS-mediated apoptosis induction remains unclear. Here, we show that MAVS binds to voltagedependent anion channel 1 (VDAC1) and induces apoptosis by caspase-3 activation, which is independent of its role in innate immunity. MAVS modulates VDAC1 protein stability by decreasing its degradative K48-linked ubiquitination. In addition, MAVS knockout mouse embryonic fibroblasts (MEFs) display reduced VDAC1 expression with a consequent reduction of the vesicular stomatitis virus (VSV)-induced apoptosis response. Notably, the upregulation of VDAC1 triggered by VSV infection is completely abolished in MAVS knockout MEFs. We thus identify VDAC1 as a target of MAVS and describe a novel mechanism of MAVS control of virus-induced apoptotic cell death.