Netrin G1 Promotes Pancreatic Tumorigenesis through Cancer-Associated Fibroblast-Driven Nutritional Support and Immunosuppression.

Pancreatic ductal adenocarcinoma (PDAC) has a poor 5-year survival rate and lacks effective therapeutics. Therefore, it is of paramount importance to identify new targets. Using multiplex data from patient tissue, three-dimensional coculturing assays, and orthotopic murine models, we identified Netrin G1 (NetG1) as a promoter of PDAC tumorigenesis.

ZBP1/DAI Drives RIPK3-Mediated Cell Death Induced by IFNs in the Absence of RIPK1.

Receptor-interacting protein kinase 1 (RIPK1) regulates cell fate and proinflammatory signaling downstream of multiple innate immune pathways, including those initiated by TNF-α, TLR ligands, and IFNs. Genetic ablation of results in perinatal lethality arising from both RIPK3-mediated necroptosis and FADD/caspase-8-driven apoptosis. IFNs are thought to contribute to the lethality of -deficient mice by activating inopportune cell death during parturition, but how IFNs activate cell death in the absence of RIPK1 is not understood.

Host functions used by hepatitis B virus to complete its life cycle: Implications for developing host-targeting agents to treat chronic hepatitis B.

Similar to other mammalian viruses, the life cycle of hepatitis B virus (HBV) is heavily dependent upon and regulated by cellular (host) functions. These cellular functions can be generally placed in to two categories: (a) intrinsic host restriction factors and innate defenses, which must be evaded or repressed by the virus; and (b) gene products that provide functions necessary for the virus to complete its life cycle. Some of these functions may apply to all viruses, but some may be specific to HBV.

Analysis of Cytokine- and Influenza A Virus-Driven RIPK3 Necrosome Formation.

In multicellular organisms, regulated cell death plays a vital role in development, adult tissue homeostasis, and clearance of damaged or infected cells. Necroptosis is one such form of regulated cell death, characterized by its reliance on receptor-interacting protein kinase 3 (RIPK3). Once activated, RIPK3 nucleates a protein complex, termed the "necrosome," which includes the adaptors RIPK1 and FADD, and the effector protein MLKL.

DAI Senses Influenza A Virus Genomic RNA and Activates RIPK3-Dependent Cell Death.

Influenza A virus (IAV) is an RNA virus that is cytotoxic to most cell types in which it replicates. IAV activates the host kinase RIPK3, which induces cell death via parallel pathways of necroptosis, driven by the pseudokinase MLKL, and apoptosis, dependent on the adaptor proteins RIPK1 and FADD. How IAV activates RIPK3 remains unknown.

RIPK3 Is Largely Dispensable for RIG-I-Like Receptor- and Type I Interferon-Driven Transcriptional Responses to Influenza A Virus in Murine Fibroblasts.

The kinase RIPK3 is a key regulator of cell death responses to a growing number of viral and microbial agents. We have found that influenza A virus (IAV)-mediated cell death is largely reliant on RIPK3 and that RIPK3-deficient mice are notably more susceptible to lethal infection by IAV than their wild-type counterparts. Recent studies demonstrate that RIPK3 also participates in regulating gene transcription programs during host pro-inflammatory and innate-immune responses, indicating that this kinase is not solely an inducer of cell death and that RIPK3-driven transcriptional responses may collaborate with cell death in promoting clearance of IAV.

RIPK3 Activates Parallel Pathways of MLKL-Driven Necroptosis and FADD-Mediated Apoptosis to Protect against Influenza A Virus.

Influenza A virus (IAV) is a lytic virus in primary cultures of many cell types and in vivo. We report that the kinase RIPK3 is essential for IAV-induced lysis of mammalian fibroblasts and lung epithelial cells. Replicating IAV drives assembly of a RIPK3-containing complex that includes the kinase RIPK1, the pseudokinase MLKL, and the adaptor protein FADD, and forms independently of signaling by RNA-sensing innate immune receptors (RLRs, TLRs, PKR), or the cytokines type I interferons and TNF-α.

Structure guided design of potent and selective ponatinib-based hybrid inhibitors for RIPK1.

RIPK1 and RIPK3, two closely related RIPK family members, have emerged as important regulators of pathologic cell death and inflammation. In the current work, we report that the Bcr-Abl inhibitor and anti-leukemia agent ponatinib is also a first-in-class dual inhibitor of RIPK1 and RIPK3. Ponatinib potently inhibited multiple paradigms of RIPK1- and RIPK3-dependent cell death and inflammatory tumor necrosis factor alpha (TNF-α) gene transcription.

Targeted Blockade of JAK/STAT3 Signaling Inhibits Ovarian Carcinoma Growth.

Ovarian carcinoma is the fifth leading cause of death among women in the United States. Persistent activation of STAT3 is frequently detected in ovarian carcinoma. STAT3 is activated by Janus family kinases (JAK) via cytokine receptors, growth factor receptor, and non-growth factor receptor tyrosine kinases.

RIP1 suppresses innate immune necrotic as well as apoptotic cell death during mammalian parturition.

The pronecrotic kinase, receptor interacting protein (RIP1, also called RIPK1) mediates programmed necrosis and, together with its partner, RIP3 (RIPK3), drives midgestational death of caspase 8 (Casp8)-deficient embryos. RIP1 controls a second vital step in mammalian development immediately after birth, the mechanism of which remains unresolved. Rip1(-/-) mice display perinatal lethality, accompanied by gross immune system abnormalities.

Interferon-induced RIP1/RIP3-mediated necrosis requires PKR and is licensed by FADD and caspases.

Interferons (IFNs) are cytokines with powerful immunomodulatory and antiviral properties, but less is known about how they induce cell death. Here, we show that both type I (α/β) and type II (γ) IFNs induce precipitous receptor-interacting protein (RIP)1/RIP3 kinase-mediated necrosis when the adaptor protein Fas-associated death domain (FADD) is lost or disabled by phosphorylation, or when caspases (e.g.

Crosstalk between the type 1 interferon and nuclear factor kappa B pathways confers resistance to a lethal virus infection.

Nuclear factor kappa B (NF-κB) and type 1 interferon (T1-IFN) signaling are innate immune mechanisms activated upon viral infection. However, the role of NF-κB and its interplay with T1-IFN in antiviral immunity is poorly understood. We show that NF-κB is essential for resistance to ectromelia virus (ECTV), a mouse orthopoxvirus related to the virus causing human smallpox.

NF-κB inhibition by bortezomib permits IFN-γ-activated RIP1 kinase-dependent necrosis in renal cell carcinoma.

Advanced renal cell carcinoma (RCC) is an invariably fatal cancer. Currently, small-molecule inhibitors that target cell growth, angiogenesis, or nutrient-sensing pathways represent the primary pharmacologic interventions for this disease, but these inhibitors only delay tumor progression and are not curative. The cytokine IFN-γ showed the potential to provide lasting remission in several phase I/II trials for advanced RCCs, but subsequent trials, including a multicenter phase III study using IFN-γ as a monotherapy for RCCs, were less promising.

Anti-CD70 immunocytokines for exploitation of interferon-γ-induced RIP1-dependent necrosis in renal cell carcinoma.

Metastatic renal cell carcinoma (RCC) is an incurable disease in clear need of new therapeutic interventions. In early-phase clinical trials, the cytokine IFN-γ showed promise as a biotherapeutic for advanced RCC, but subsequent trials were less promising. These trials, however, focused on the indirect immunomodulatory properties of IFN-γ, and its direct anti-tumor effects, including its ability to kill tumor cells, remains mostly unexploited.

NF-YA underlies EZH2 upregulation and is essential for proliferation of human epithelial ovarian cancer cells.

Epithelial ovarian cancer (EOC) accounts for the most gynecologic malignancy-associated deaths in the United States. Enhancer of zeste homolog 2 (EZH2), which silences gene expression through generating trimethylation on lysine 27 residue of histone H3 (H3K27Me3), is often overexpressed in EOCs and has been suggested as a therapeutic target. However, the mechanism underlying EZH2 overexpression in EOCs is unknown.

Identification of STAT2 serine 287 as a novel regulatory phosphorylation site in type I interferon-induced cellular responses.

STAT2 is a positive modulator of the transcriptional response to type I interferons (IFNs). STAT2 acquires transcriptional function by becoming tyrosine phosphorylated and imported to the nucleus following type I IFN receptor activation. Although most STAT proteins become dually phosphorylated on specific tyrosine and serine residues to acquire full transcriptional activity, no serine phosphorylation site in STAT2 has been reported.

Inactivation of ribosomal protein L22 promotes transformation by induction of the stemness factor, Lin28B.

Ribosomal protein (RP) mutations in diseases such as 5q- syndrome both disrupt hematopoiesis and increase the risk of developing hematologic malignancy. However, the mechanism by which RP mutations increase cancer risk has remained an important unanswered question. We show here that monoallelic, germline inactivation of the ribosomal protein L22 (Rpl22) predisposes T-lineage progenitors to transformation.

Requirement of FADD, NEMO, and BAX/BAK for aberrant mitochondrial function in tumor necrosis factor alpha-induced necrosis.

Necroptosis represents a form of alternative programmed cell death that is dependent on the kinase RIP1. RIP1-dependent necroptotic death manifests as increased reactive oxygen species (ROS) production in mitochondria and is accompanied by loss of ATP biogenesis and eventual dissipation of mitochondrial membrane potential. Here, we show that tumor necrosis factor alpha (TNF-α)-induced necroptosis requires the adaptor proteins FADD and NEMO.

NF-kappaB protects cells from gamma interferon-induced RIP1-dependent necroptosis.

Interferons (IFNs) are cytokines with well-described immunomodulatory and antiviral properties, but less is known about the mechanisms by which they promote cell survival or cell death. Here, we show that IFN-γ induces RIP1 kinase-dependent necroptosis in mammalian cells deficient in NF-κB signaling. Induction of necroptosis by IFN-γ was found to depend on Jak1 and partially on STAT1.

Distinct roles for the NF-kappa B RelA subunit during antiviral innate immune responses.

Production of type I interferons (IFNs; prominently, IFN-α/β) following virus infection is a pivotal antiviral innate immune response in higher vertebrates. The synthesis of IFN-β proceeds via the virus-induced assembly of the transcription factors IRF-3/7, ATF-2/c-Jun, and NF-κB on the ifnβ promoter. Surprisingly, recent data indicate that the NF-κB subunit RelA is not essential for virus-stimulated ifnβ expression.