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Necroptosis as a molecular program, rather than simply incidental cell death, was established by elucidating the roles of receptor interacting protein (RIP) kinases 1 and 3, along with their downstream partner, mixed lineage kinase-like domain protein (MLKL). Previous studies suggested that phosphoglycerate mutase family member 5 (PGAM5), a mitochondrial protein that associates with RIP1/RIP3/MLKL complex, promotes necroptosis. We have generated mice deficient in the pgam5 gene and surprisingly found PGAM5-deficiency exacerbated rather than reduced necroptosis in response to multiple in vitro and in vivo necroptotic stimuli, including ischemic reperfusion injury (I/R) in the heart and brain. Electron microscopy, biochemical, and confocal analysis revealed that PGAM5 is indispensable for the process of PINK1 dependent mitophagy which antagonizes necroptosis. The loss of PGAM5/PINK1 mediated mitophagy causes the accumulation of abnormal mitochondria, leading to the overproduction of reactive oxygen species (ROS) that worsen necroptosis. Our results revise the former proposal that PGAM5 acts downstream of RIP1/RIP3 to mediate necroptosis. Instead, PGAM5 protects cells from necroptosis by independently promoting mitophagy. PGAM5 promotion of mitophagy may represent a therapeutic target for stroke, myocardial infarction and other diseases caused by oxidative damage and necroptosis.

mTOR and autophagy During autophagy, double-membrane autophagosomes sequester intracellular components and then fuse with lysosomes to form autolysosomes in which cargo is degraded. Under starvation conditions, the nutrient-responsive kinase, target of rapamycin (TOR), is inhibited, which results in an induction of autophagy. In this study, Yu et al . report a negative feedback mechanism by which lysosomes are reformed after the termination of autophagy. They demonstrate that upon prolonged starvation conditions, mTOR is reactivated, which attenuates autophagy and results in the formation of tubules and vesicles that extrude from autolysosomes. These mature into functional lysosomes, thereby restoring lysosome numbers in the cell. This feedback mechanism tightly couples nutritional status with the induction and termination of autophagy. When cells are starved, the enzyme TOR is inhibited, inducing autophagy. In this process, autophagosomes sequester intracellular components and then fuse with lysosomes, producing autolysosomes in which cargo is degraded to regenerate nutrients. Now, a mechanism is revealed by which lysosomes are re-formed. When starvation conditions are prolonged, mTOR is re-activated; this attenuates autophagy and results in tubules and vesicles extruding from the autolysosome and maturing into functional lysosomes. Autophagy is an evolutionarily conserved process by which cytoplasmic proteins and organelles are catabolized 1 , 2 . During starvation, the protein TOR (target of rapamycin), a nutrient-responsive kinase, is inhibited, and this induces autophagy. In autophagy, double-membrane autophagosomes envelop and sequester intracellular components and then fuse with lysosomes to form autolysosomes, which degrade their contents to regenerate nutrients. Current models of autophagy terminate with the degradation of the autophagosome cargo in autolysosomes 3 , 4 , 5 , but the regulation of autophagy in response to nutrients and the subsequent fate of the autolysosome are poorly understood. Here we show that mTOR signalling in rat kidney cells is inhibited during initiation of autophagy, but reactivated by prolonged starvation. Reactivation of mTOR is autophagy-dependent and requires the degradation of autolysosomal products. Increased mTOR activity attenuates autophagy and generates proto-lysosomal tubules and vesicles that extrude from autolysosomes and ultimately mature into functional lysosomes, thereby restoring the full complement of lysosomes in the cell—a process we identify in multiple animal species. Thus, an evolutionarily conserved cycle in autophagy governs nutrient sensing and lysosome homeostasis during starvation.

CD55 prevents convertase enzyme formation in the complement cascade, acting as a brake on complement activation. Inactivating mutations in CD55 result in hyperactivation of complement, angiopathic thrombosis, and protein-losing enteropathy.

The T lymphocyte, especially its capacity for antigen-directed cytotoxicity, has become a central focus for engaging the immune system in the fight against cancer. Basic science discoveries elucidating the molecular and cellular biology of the T cell have led to new strategies in this fight, including checkpoint blockade, adoptive cellular therapy and cancer vaccinology. This area of immunological research has been highly active for the past 50 years and is now enjoying unprecedented bench-to-bedside clinical success. Here, we provide a comprehensive historical and biological perspective regarding the advent and clinical implementation of cancer immunotherapeutics, with an emphasis on the fundamental importance of T lymphocyte regulation. We highlight clinical trials that demonstrate therapeutic efficacy and toxicities associated with each class of drug. Finally, we summarize emerging therapies and emphasize the yet to be elucidated questions and future promise within the field of cancer immunotherapy.T cells play a central role in immune responses to cancer. In this guide to cancer immunotherapy, the authors provide a comprehensive historical and biological perspective on cancer immunotherapy, with a focus on current and emerging therapeutic approaches that harness T cells to fight cancer.

Protein-Losing EnteropathyLoss of plasma proteins into the gastrointestinal tract may be due to capillary diffusion of proteins into the interstitium, epithelial permeability, or leakage and rupture of dilated lacteals.

Autophagy is a conserved cellular process to degrade and recycle cytoplasmic components. During autophagy, lysosomes fuse with an autophagosome to form an autolysosome. Sequestered components are degraded by lysosomal hydrolases and presumably released into the cytosol by lysosomal efflux permeases. Following starvation-induced autophagy, lysosome homeostasis is restored by autophagic lysosome reformation (ALR) requiring activation of the \"target of rapamycin\" (TOR) kinase. Spinster (Spin) encodes a putative lysosomal efflux permease with the hallmarks of a sugar transporter. Drosophila spin mutants accumulate lysosomal carbohydrates and enlarged lysosomes. Here we show that defects in spin lead to the accumulation of enlarged autolysosomes. We find that spin is essential for mTOR reactivation and lysosome reformation following prolonged starvation. Further, we demonstrate that the sugar transporter activity of Spin is essential for ALR.

LRRK2 was recently identified as a major susceptibility gene for Crohn＇s disease （CD） by genome-wide association studies （GWAS）. LRRK2 deficiency in mice confers enhanced susceptibility to experimental colitis. In this research highlight, we discuss the current understanding of LRRK2 in the context of colitis, and postulate the future directions.

Background CD55 deficiency with hyper-activation of complement, angiopathic thrombosis, and protein-losing enteropathy (CHAPLE) disease is ultra-rare (< 100 children or young adults worldwide) and potentially fatal. The study used mixed-methods approaches to assess how pozelimab impacts the signs and symptoms of CHAPLE disease from the patient perspective by combining within-trial interviews and clinical outcome assessments (COAs) (ClinicalTrials.gov, NCT04209634). Methods Interviews conducted with patients/caregivers at screening and week 24 assessed the signs and symptoms of CHAPLE disease, including those which were most bothersome, and evaluated the change. Patients/caregivers and clinicians completed the COAs; interview data contextualized the meaningfulness of change. Results Ten patients (aged 3–19 years) were enrolled; caregivers contributed to nine interviews. Abdominal pain, diarrhea, facial and peripheral edema, nausea, and vomiting are the core signs and symptoms of CHAPLE disease (≥ 90% patients experienced pre-treatment); the most bothersome signs and symptoms were abdominal pain ( n  = 9) and facial edema ( n  = 1). All core signs and symptoms were reported as resolved at week 24 interviews. Severity on global assessments changed from “mild” to “very severe” at baseline to “no signs or symptoms” at week 24. Interview results were generally consistent with sign- or symptom-specific COA scores. Conclusions Patients with CHAPLE disease treated with pozelimab for 24 weeks experienced complete resolution of core signs and symptoms. Mixed-methods approaches can contextualize the patient experience (how patients feel and function) in rare disease trials. Trial registration Clinicaltrials.gov, NCT04209634, registered December 24, 2019, https://classic.clinicaltrials.gov/ct2/show/NCT04209634 .

Owing to advances in genomics that enable differentiation of molecular aetiologies, patients with monogenic inflammatory bowel disease (mIBD) potentially have access to genotype-guided precision medicine. In this Expert Recommendation, we review the therapeutic research landscape of mIBD, the reported response to therapies, the medication-related risks and systematic bias in reporting. The mIBD field is characterized by the absence of randomized controlled trials and is dominated by retrospective observational data based on case series and case reports. More than 25 off-label therapeutics (including small-molecule inhibitors and biologics) as well as cellular therapies (including haematopoietic stem cell transplantation and gene therapy) have been reported. Heterogeneous reporting of outcomes impedes the generation of robust therapeutic evidence as the basis for clinical decision making in mIBD. We discuss therapeutic goals in mIBD and recommend standardized reporting (mIBD REPORT (monogenic Inflammatory Bowel Disease Report Extended Phenotype and Outcome of Treatments) standards) to stratify patients according to a genetic diagnosis and phenotype, to assess treatment effects and to record safety signals. Implementation of these pragmatic standards should help clinicians to assess the therapy responses of individual patients in clinical practice and improve comparability between observational retrospective studies and controlled prospective trials, supporting future meta-analysis.In this Expert Recommendation, Uhlig and colleagues review the therapeutic landscape for monogenic inflammatory bowel disease and propose recommendations for standardized reporting of clinical outcomes.

The signaling adaptor TRAF6 is a ubiquitin E3 ligase whose activity can lead to activation of NF-κB and MAPK pathways. New data based on the structure of TRAF6 in complex with the ubiquitin E2 Ubc13 suggest that other TRAFs do not interact with Ubc13 and that oligomerization of TRAF6 is needed for downstream signal transduction. Tumor necrosis factor (TNF) receptor–associated factor (TRAF)-6 mediates Lys63-linked polyubiquitination for NF-κB activation via its N-terminal RING and zinc finger domains. Here we report the crystal structures of TRAF6 and its complex with the ubiquitin-conjugating enzyme (E2) Ubc13. The RING and zinc fingers of TRAF6 assume a rigid, elongated structure. Interaction of TRAF6 with Ubc13 involves direct contacts of the RING and the preceding residues, and the first zinc finger has a structural role. Unexpectedly, this region of TRAF6 is dimeric both in the crystal and in solution, different from the trimeric C-terminal TRAF domain. Structure-based mutagenesis reveals that TRAF6 dimerization is crucial for polyubiquitin synthesis and autoubiquitination. Fluorescence resonance energy transfer analysis shows that TRAF6 dimerization induces higher-order oligomerization of full-length TRAF6. The mismatch of dimeric and trimeric symmetry may provide a mode of infinite oligomerization that facilitates ligand-dependent signal transduction of many immune receptors.