BACKGROUND: High mobility group box-1 (HMGB1) is an endogenous danger signal that mediates activation of the innate immune response including NLR pyrin domain containing 3 (NLRP3) inflammasome activation and proinflammatory cytokine release. Although HMGB1 and NLRP3 have been implicated in the pathophysiology of seizures, the correlation between HMGB1 and NLRP3 expression has not been determined in children with febrile seizures (FS). To explore the relationship between extra-cellular HMGB1 and NLRP3 in children with FS, we analyzed serum HMGB1, NLRP3, caspase-1, and proinflammatory cytokines in patients with FS.
METHODS: Thirty children with FS and thirty age-matched febrile controls were included in this study. Blood was obtained from the children with FS within 1 h of the time of the seizure; subsequently, the serum contents of HMGB1, NLRP3, caspase-1, interleukin (IL)-1β, interleukin (IL)-6, and tumour necrosis factor-α (TNF-α) were determined by enzyme-linked immunosorbent assay. The Mann‒Whitney U test was used to compare serum cytokine levels between FS patients and controls. Spearman\'s rank correlation coefficient was calculated to detect significant correlations between cytokine levels.
RESULTS: Serum levels of HMGB1, NLRP3, caspase-1, IL-1β, IL-6, and TNF-α were significantly higher in FS patients than in febrile controls (p < 0.05). Serum levels of HMGB1 were significantly correlated with levels of NLRP3 and caspase-1 (both, p < 0.05). Serum levels of caspase-1 were significantly correlated with levels of IL-1β (p < 0.05). Serum levels of IL-1β were significantly correlated with levels of IL-6 and TNF-α (p < 0.05).
CONCLUSIONS: HMGB1 is up-regulated in the peripheral serum of FS patients, which may be responsible, at least in part, for the increased expression of NLRP3 and Caspase-1. Increased expression of caspase-1 was significantly associated with elevated serum levels of IL-1β. Given that activated Caspase-1 directly regulates the expression of mature IL-1β and positively correlates with activation of the NLRP3 inflammasome, our data suggest that increased levels of peripheral HMGB1 possibly mediate IL-1β secretion through the activation of the NLRP3 inflammasome in children with FS. Thus, both HMGB1 and NLRP3 might be potential targets for preventing or limiting FS.

Metacaspases are highly conserved in plants and play essential roles in mediating programmed cell death, biotic and abiotic stress responses, and damage-induced innate immunity. Ca2+ signaling induced by plant damage leads to activation of metacaspase 4 from Arabidopsis thaliana (AtMC4), which subsequently processes a plant elicitor peptide to trigger downstream immuno-response. To understand the structural basis of AtMC4 activation by Ca2+, we previously determined its crystal structure and performed in-crystal Ca2+ treatment to probe activation-associated conformational changes. To enable structure determination and in-crystal Ca2+ activation analysis, we used microcrystals and related methods which were essential for our successful approach. Here we describe in detail the methods that we used for determination of AtMC4 structure using single-wavelength isomorphous replacement with anomalous signals assembled from 22 microcrystals. We also describe the method for in-crystal Ca2+ soaking, microcrystal data collection, data assembly and analysis to obtain the activated structure of AtMC4 from 91 micro-sized crystals. The described methods may be useful to study other plant metacaspases and more broadly other plant enzymes for their structure determination and in-crystal functional characterization.

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Caspases play a vital role during apoptosis. In addition to apoptosis, caspases play a role in cytokine gene induction and work to inhibit apoptosis. In order for individuals to thrive with useful tissue growth, the rate of cell growth and division must surpass the rate of cell division. It is well established that excessive cell death of embryonic cells is a vital process occurring before structural abnormalities, regardless of their nature. Here we describe a 13-month-old male patient with a 4.7Mb interstitial duplication of chromosome 2q33.1. This duplication was identified by chromosomal microarray (CMA) which is the first-tier clinical diagnostic test to identify copy number variants (CNVs) for patients with unexplained developmental delay or intellectual disability. This patient presents with global developmental delay, especially in speech, language, hypotonia, and bilateral simian creases. The duplicated region contains several disease-causing genes. We believe that the phenotype in this patient\'s case was likely related to the gain of caspase 8 and 10 genes.

As part of an ongoing effort to discover inhibitors of caspase-1 with an optimized selectivity and biopharmaceutical profile, acylsulfonamides were explored as carboxylate isosteres for caspase inhibitors. Acylsulfonamide analogues of the clinically investigated caspase-1 inhibitor VRT-043198 and of the pan-caspase inhibitor Z-VAD-CHO were synthesized. The isostere-containing analogues with an aldehyde warhead had inhibitory potencies comparable to the carboxylate references. In addition, the conformational and tautomeric characteristics of these molecules were determined using 1H- and 13C-based NMR. The propensity of acylsulfonamides with an aldehyde warhead to occur in a ring-closed conformation at physiological pH significantly increases the sensitivity to hydrolysis of the acylsulfonamide moiety, yielding the parent carboxylate containing inhibitors. These results indicate that the acylsulfonamide analogues of the aldehyde-based inhibitor VRT-043198 might have potential as a novel type of prodrug for the latter. Finally, inhibition of caspase 1 and 11 mediated inflammation in mouse macrophages was found to correlate with the potencies of the compounds in enzymatic assays.

BACKGROUND: Apoptotic dysregulation plays a role in the pathogenesis of polycystic ovary syndrome (PCOS).
OBJECTIVE: To evaluate circulatory apoptotic markers and oxidative stress in patients with PCOS.
METHODS: Forty-four women with PCOS, and 44 healthy women as controls were enrolled in the study. Oxidative stress parameters and caspases levels were measured in serum.
RESULTS: The caspase 9 level was significantly lower and related with oxidant status in patients with PCOS, while the circulating levels of caspases 3 and 7 were statistically similar in both groups.
CONCLUSIONS: This study is the first report demonstrating the circulating levels of apoptotic markers and their relationship with oxidant status in PCOS.
CONCLUSIONS: The circulating caspase 9 and oxidant status might contribute to apoptotic dysregulation in PCOS.

Caspases are a family of cysteine-dependent proteases known to be involved in the process of programmed cell death in metazoans. Recently, cyanobacteria were also found to contain caspase-like proteins, but their existence has only been identified in silico up to now. Here, we present the first experimental characterisation of a prokaryotic caspase homologue. We have expressed the putative caspase-like gene MaOC1 from the toxic bloom-forming cyanobacterium Microcystis aeruginosa PCC 7806 in Escherichia coli. Kinetic characterisation showed that MaOC1 is an endopeptidase with a preference for arginine in the P1 position and a pH optimum of 7.5. MaOC1 exhibited high catalytic rates with the kcat /KM value for Z-RR-AMC substrate of the order 10(6)  M(-1)  s(-1). In contrast to plant or metazoan caspase-like proteins, whose activity is calcium-dependent or requires dimerisation for activation, MaOC1 was activated by autocatalytic processing after residue Arg219, which separated the catalytic domain and the remaining 55 kDa subunit. The Arg219Ala mutant was resistant to autoprocessing and exhibited no proteolytic activity, confirming that processing of MaOC1 is a prerequisite for its activity. Due to their structural and functional differences to other known caspase-like proteins, we suggest to name these evolutionary primitive proteins orthocaspases.

We present a de novo 1.4 Mb deletion of chromosome 19p13.11-p13.12 in a 16 year old boy with intellectual disability, autistic features, microcephaly, hearing impairment, hypertrichosis, synophrys, protruding front teeth, and other dysmorphic features. By comparing our patient to reported cases with overlapping deletions, we have refined the minimal critical region of hypertrichosis, synophrys, and protruding front teeth to 305 kb, a region containing seven genes. CASP14, which is considered a good candidate gene for hypertrichosis, is not included in this region, questioning the causal relationship.

AZFc deletions of the Y chromosome are the major known genetic cause of spermatogenetic failure. Meiotic studies have shown a prevalence of synaptonemal complex fragmentation and an excess of early-stage sperm cells, suggesting that the maturation block could involve apoptosis. We present a prospective and observational study of apoptotic markers in the sperm of four AZFc-deleted patients and two non-obstructive azoospermic controls without an AZFc deletion. Polycaspases assays and terminal deoxynucleotidyl transferase dUDP nick-end labelling (TUNEL) assays were combined to evaluate the incidence of apoptosis in pre-meiotic, meiotic and post-meiotic germs cells identified, respectively, using anti-melanoma-associated antigen A4 (MAGE-A4), anti-synaptonemal complex protein 3 (SCP3) and anti-sperm acrosome membrane-associated protein 1 (SPACA1) antibodies. We detected apoptosis at all stages of AZFc-deletion spermatogenesis. Using the caspase assay, the incidence of positive cells was found to be heterogeneous for pre-meiotic (from 4.8 to 84.5%) and meiotic stages (from 7.9 to 57.6%), while for post-meiotic cells, the mean incidence was 6% in AZFc-deleted patients compared with 26.5% in controls (P < 0.05). Using the TUNEL assay, the mean percentage with DNA fragmentation for meiotic cells was 54.0% in AZFc-deleted patients compared with 20.3% in controls (P < 0.05), while the percentage of TUNEL-positive post-meiotic cells ranged from 5.3 to 44.7%. Spermatocyte loss in AZFc-deleted patients occurs via the apoptotic pathway. In post-meiotic cells, the lower incidence of apoptosis in testis from three of the four AZFc-deleted patients, compared with controls, is consistent with AZFc deletions having little negative impact on sperm quality.

Myristoylation, the addition of a 14-carbon fatty acid to the N-terminal glycine of a protein, is key to protein-membrane and protein-protein interactions. Typically, myristoylation occurs cotranslationally; however, post-translational myristoylation of caspase-cleaved proteins is now emerging as a well-established protein modification and as a novel regulator of apoptosis. To identify additional post-translationally myristoylated proteins, we engineered a plasmid vector encoding for a caspase-cleavable reporter protein named tandem reporter assay for myristoylation of proteins post-translationally (TRAMPP). pTRAMPP consists of tdTomato-DEVD-\"test myristoylation sequence\"-enhanced green fluorescent protein (EGFP). After induction of apoptosis, the reporter protein is cleaved by caspases, which frees a new N-terminal glycine residue attached to EGFP that can be myristoylated. We used pTRAMPP in appropriately transfected cells to identify 7 post-translationally myristoylated proteins. First, we confirmed the post-translational myristoylation of two previously identified putative substrates, cytoplasmic dynein intermediate chain 2A and PKCε (ctPKCε), and identified 5 more caspase-cleaved potential substrates for myristoylation that include the antiapoptotic regulator of apoptosis, Mcl-1, and the causative agent of Huntington\'s disease, huntingtin protein. Further investigation revealed that post-translationally myristoylated ctPKCε localized to membranes and increased Erk signaling and degradation of the proapoptotic protein Bim, which prevented a significant loss of mitochondrial potential of 17% over nonmyristoylated ctPKCε in HeLa cells in the presence of apoptotic stimuli. Taken together, these findings suggest a possible antiapoptotic role for post-translationally myristoylated caspase-cleaved ctPKCε.