For "U" the bell tolls: Pseudouridine evades TLR detection.

TLRs detect pathogen-derived uridine but not endogenous pseudouridine, which promotes host defense without autoimmunity. This principle is critical for the safe design of mRNA-based therapeutics, but the underlying mechanisms driving differential innate immune activation were unknown. In a recent issue of Cell, Bérouti et al.

Three decades of caspases and RIPKs in life and death.

Caspases and RIPKs are critical regulators of life and death. These molecules have roles in innate immunity and cell death that drive host defense, development, and tumor immunity, but their activation can also contribute to aberrant inflammation and inflammatory disease. This review revisits three decades of genetic studies that have elucidated the critical functions of caspases and RIPKs, synthesizing seminal findings in development, lytic cell death pathways, inflammation, disease pathology, and therapeutic innovation.

CETSA-MS unveils novel targets engaged by rigosertib to promote anti-tumor activity and inflammatory responses.

Rigosertib (RGS) is a small-molecule inhibitor known to interfere with multiple disease signaling pathways. Despite its promise as an anti-cancer drug, the exact mechanisms of its action and rational for its observed clinical efficacy remain subjects of ongoing research. Our study aimed to elucidate the mechanism of action of rigosertib and to identify its novel targets.

ExSPECKt the unexpected: NLRP3-caspase-8-dependent cell death in RBCs.

Red blood cell (RBC) lysis can cause morbidity and mortality. However, the molecular mechanisms underlying RBC lysis are not fully characterized, limiting therapeutic options. In this issue of Cell, Chen et al.

HCK regulates NLRP12-mediated PANoptosis.

NOD-like receptors (NLRs) are a highly conserved family of cytosolic pattern recognition receptors that drive innate immune responses against pathogens, pathogen-associated molecular patterns, damage-associated molecular patterns, and homeostatic disruptions. Within the NLR family, NLRP12 was recently identified as a key regulator of PANoptosis, which is an innate immune, lytic cell death pathway initiated by innate immune sensors and driven by caspases and RIPKs through PANoptosome complexes. While NLRP12 activation is critical for maintaining homeostasis, aberrant activation has been implicated in a broad range of disorders, including cancers and metabolic, infectious, autoinflammatory, and hemolytic diseases.

Caspases: structural and molecular mechanisms and functions in cell death, innate immunity, and disease.

Caspases are critical regulators of cell death, development, innate immunity, host defense, and disease. Upon detection of pathogens, damage-associated molecular patterns, cytokines, or other homeostatic disruptions, innate immune sensors, such as NLRs, activate caspases to initiate distinct regulated cell death pathways, including non-lytic (apoptosis) and innate immune lytic (pyroptosis and PANoptosis) pathways. These cell death pathways are driven by specific caspases and distinguished by their unique molecular mechanisms, supramolecular complexes, and enzymatic properties.

Evolutionary and Functional Analysis of Caspase-8 and ASC Interactions to Drive Lytic Cell Death, PANoptosis.

Caspases are evolutionarily conserved proteins essential for driving cell death in development and host defense. Caspase-8, a key member of the caspase family, is implicated in nonlytic apoptosis, as well as lytic forms of cell death. Recently, caspase-8 has been identified as an integral component of PANoptosomes, multiprotein complexes formed in response to innate immune sensor activation.

Innate immune sensor NLRP3 drives PANoptosome formation and PANoptosis.

Inflammasomes are multiprotein innate immune complexes formed in response to infections, tissue damage, or cellular stress that promote the maturation and release of IL-1β/IL-18 and are implicated in lytic cell death. The NLRP3 inflammasome is canonically activated by an initial priming event followed by an activation stimulus, leading to rapid cell death that occurs through caspase-1 (CASP1) and gasdermin D (GSDMD) activation, called pyroptosis. CASP1- and GSDMD-deficient cells are protected from the rapid LPS plus ATP-induced pyroptosis.

The critical role of the ZBP1-NINJ1 axis and IRF1/IRF9 in ethanol-induced cell death, PANoptosis, and alcohol-associated liver disease.

Innate immunity provides the critical first line of defense against infection and sterile triggers. Cell death is a key component of the innate immune response to clear pathogens, but excessive or aberrant cell death can induce inflammation, cytokine storm, and pathology, making it a central molecular mechanism in inflammatory diseases. Alcohol-associated liver disease (ALD) is one such inflammatory disease, but the specific innate immune mechanisms driving pathology in this context remain unclear.

Extracellular vesicles transport gasdermin pores, amplifying inflammatory cell death.

Lytic cell death is crucial for antimicrobial and antitumor immunity; however, unchecked pyroptosis drives pathology in sepsis. Wright et al. demonstrate that widespread cell death following pyroptosis is propagated by extracellular vesicles (EVs) carrying gasdermin D (GSDMD) pores that become integrated into the membrane of neighboring cells, driving inflammatory cell death.

The story behind the emergence of different forms of cell death.

Various types of cell death program are needed for cells to respond to changes in physiological conditions. In this collection of Voices, we asked scientists to tell the story behind their contributions to the identification and mechanistic dissection of cell death pathways and to discuss future directions for such research.

Inflammasomes and their role in PANoptosomes.

Inflammasomes are multiprotein signaling structures in the innate immune system that drive cell death and inflammatory responses. These protein complexes generally comprise an innate immune sensor, the adaptor protein ASC, and the inflammatory protease caspase-1. Inflammasomes are formed when a cytosolic sensor, also known as a pattern recognition receptor, senses its cognate ligand, which can include microbial components, endogenous damage/danger signals, or environmental stimuli.

Sensory nerves unlock the TOLL-7 gate for cancer spread.

Cancers hijack the nervous system for growth and spread. Thus, disrupting neuron-cancer crosstalk holds promise for blocking metastasis. Recently, Padmanaban et al.

Innate immune sensing of cell death in disease and therapeutics.

Innate immunity, cell death and inflammation underpin many aspects of health and disease. Upon sensing pathogens, pathogen-associated molecular patterns or damage-associated molecular patterns, the innate immune system activates lytic, inflammatory cell death, such as pyroptosis and PANoptosis. These genetically defined, regulated cell death pathways not only contribute to the host defence against infectious disease, but also promote pathological manifestations leading to cancer and inflammatory diseases.

Chromatin Regulator SMARCA4 Is Essential for MHV-Induced Inflammatory Cell Death, PANoptosis.

The innate immune system serves as the first line of defense against β-coronaviruses (β-CoVs), a family of viruses that includes SARS-CoV-2. Viral sensing via pattern recognition receptors triggers inflammation and cell death, which are essential components of the innate immune response that facilitate viral clearance. However, excessive activation of the innate immune system and inflammatory cell death can result in uncontrolled release of proinflammatory cytokines, resulting in cytokine storm and pathology.

Classical apoptotic stimulus, staurosporine, induces lytic inflammatory cell death, PANoptosis.

Innate immunity is the body's first line of defense against disease, and regulated cell death is a central component of this response that balances pathogen clearance and inflammation. Cell death pathways are generally categorized as non-lytic and lytic. While non-lytic apoptosis has been extensively studied in health and disease, lytic cell death pathways are also increasingly implicated in infectious and inflammatory diseases and cancers.

Defining PANoptosis: Biochemical and Mechanistic Evaluation of Innate Immune Cell Death Activation.

The innate immune system is the first line of host defense. Innate immune activation utilizes pattern recognition receptors to detect pathogens, pathogen-associated and damage-associated molecular patterns (PAMPs and DAMPs), and homeostatic alterations and drives inflammatory signaling pathways and regulated cell death. Cell death activation is critical to eliminate pathogens and aberrant or damaged cells, while excess activation can be linked to inflammation, tissue damage, and disease.

Erratum to "Fungal cell wall components modulate our immune system" [Cell Surf. 7 (2021) 100067].

[This corrects the article DOI: 10.1016/j.tcsw.

NLRC5 senses NAD depletion, forming a PANoptosome and driving PANoptosis and inflammation.

NLRs constitute a large, highly conserved family of cytosolic pattern recognition receptors that are central to health and disease, making them key therapeutic targets. NLRC5 is an enigmatic NLR with mutations associated with inflammatory and infectious diseases, but little is known about its function as an innate immune sensor and cell death regulator. Therefore, we screened for NLRC5's role in response to infections, PAMPs, DAMPs, and cytokines.

The protein phosphatase PP6 promotes RIPK1-dependent PANoptosis.

Background: The innate immune system serves as the first line of host defense. Transforming growth factor-β-activated kinase 1 (TAK1) is a key regulator of innate immunity, cell survival, and cellular homeostasis. Because of its importance in immunity, several pathogens have evolved to carry TAK1 inhibitors.

Voices: Challenges and opportunities in regulating the immune system.

The rise of immunotherapy and mRNA vaccines has underscored the power of modulating the immune system for a desired response. In this Voices piece, the Cell Chemical Biology editors ask researchers from a range of backgrounds: what are some major challenges and opportunities facing the field in coming years?