Deubiquitinase UCHL1 promotes angiogenesis and blood-spinal cord barrier function recovery after spinal cord injury by stabilizing Sox17.

Improving the function of the blood-spinal cord barrier (BSCB) benefits the functional recovery of mice following spinal cord injury (SCI). The death of endothelial cells and disruption of the BSCB at the injury site contribute to secondary damage, and the ubiquitin-proteasome system is involved in regulating protein function. However, little is known about the regulation of deubiquitinated enzymes in endothelial cells and their effect on BSCB function after SCI. We observed that Sox17 is predominantly localized in endothelial cells and is significantly upregulated after SCI and in LPS-treated brain microvascular endothelial cells. In vitro Sox17 knockdown attenuated endothelial cell proliferation, migration, and tube formation, while in vivo Sox17 knockdown inhibited endothelial regeneration and barrier recovery, leading to poor functional recovery after SCI. Conversely, in vivo overexpression of Sox17 promoted angiogenesis and functional recovery after injury. Additionally, immunoprecipitation-mass spectrometry revealed the interaction between the deubiquitinase UCHL1 and Sox17, which stabilized Sox17 and influenced angiogenesis and BSCB repair following injury. By generating UCHL1 conditional knockout mice and conducting rescue experiments, we further validated that the deubiquitinase UCHL1 promotes angiogenesis and restoration of BSCB function after injury by stabilizing Sox17. Collectively, our findings present a novel therapeutic target for treating SCI by revealing a potential mechanism for endothelial cell regeneration and BSCB repair after SCI.

Inhibition of BRD4 expression attenuates the inflammatory response and apoptosis by downregulating the HMGB-1/NF-κB signaling pathway following traumatic brain injury in rats.

Neuroinflammation plays an important part in secondary traumatic brain injury (TBI). Bromodomain-4 (BRD4) exerts specific proinflammatory effects in various neuropathological conditions. However, the underlying mechanism of action of BRD4 after TBI is not known. We measured BRD4 expression after TBI and investigated its possible mechanism of action. We established a model of craniocerebral injury in rats. After different intervention measures, we used western blotting, immunofluorescence, real-time reverse transcription-quantitative polymerase chain reaction, neuronal apoptosis, and behavioral tests to evaluate the effect of BRD4 on brain injury. At 72 h after brain injury, BRD4 overexpression aggravated the neuroinflammatory response, neuronal apoptosis, neurological dysfunction, and blood-brain-barrier damage, whereas upregulating expression of HMGB-1 and NF-κB had the opposite effect. Glycyrrhizic acid could reverse the proinflammatory effect of BRD4 overexpression upon TBI. Our results suggest that: (i) BRD4 may have a proinflammatory role in secondary brain injury through the HMGB-1/NF-κB signaling pathway; (ii) inhibition of BRD4 expression may play a part in secondary brain injury. BRD4 could be targeted therapy strategy for brain injury.

Sesquiterpene nootkatone counteracted the melamine-induced neurotoxicity via repressing of oxidative stress, inflammatory, and apoptotic trajectories.

Melamine (ML), a chemical substance of high nitrogen content, is used as a food adulterant. Former evidences implied that ML could induce a variety of toxic effects including neurotoxicity and cognitive impairment. Therefore, the aim of this study was to delineate the protective effect of the nootkatone (NK) against ML-induced neural adverse effects. Rats were orally pretreated with NK (5 and 10 mg/kg) prior to the oral administration of ML (700 mg/kg) for a period of 28 days. Our findings unveiled remarkable alleviating effect of NK on MK-induced neurobehavioral disturbance in open field test. Furthermore, NK lessened ML-caused increases in the acetylcholine esterase level in the brain tissue of exposed rats. NK also decreased the neural oxidative stress as represented by elevated levels of SOD, CAT, and GSH along with decreased MDA and NO levels. Upregulated mRNA expression levels of neural NRF-2 and HO-1 were noticed after NK administration. Remarkable anti-inflammatory impact was prominent by decreased neural IL-1ß, and TNF-α along with downregulated NF-κB and TLR-4 gene expression levels in NK-treated rats. Noteworthily, pre-treatment with NK decreased the immune reaction of RAGE and HMGB-1 induced by oral ML exposure. Brain histological examination validated the obtained biochemical and molecular results. To sum up, these outcomes reveal that NK successfully alleviated the neural damage induced by ML via blocking of oxidative stress, and inflammatory signaling pathways. Consequently, our study may suggest NK as a new effective therapeutic supplement for treatment of ML-mediated neurotoxicity in rats via inhibition of HMGB-1-RAGE/TLR-4/NF-κB.

Inflachromene attenuates seizure severity in mouse epilepsy models via inhibiting HMGB1 translocation.

Epilepsy is not well controlled by current anti-seizure drugs (ASDs). High mobility group box 1 (HMGB1) is a DNA-binding protein in the nucleus regulating transcriptional activity and maintaining chromatin structure and DNA repair. In epileptic brains, HMGB1 is released by activated glia and neurons, interacting with various receptors like Toll-like receptor 4 (TLR4) and downstream glutamatergic NMDA receptor, thus enhancing neural excitability. But there is a lack of small-molecule drugs targeting the HMGB1-related pathways. In this study we evaluated the therapeutic potential of inflachromene (ICM), an HMGB-targeting small-molecule inhibitor, in mouse epilepsy models. Pentylenetetrazol-, kainic acid- and kindling-induced epilepsy models were established in mice. The mice were pre-treated with ICM (3, 10 mg/kg, i.p.). We showed that ICM pretreatment significantly reduced the severity of epileptic seizures in all the three epilepsy models. ICM (10 mg/kg) exerted the most apparent anti-seizure effect in kainic acid-induced epileptic status (SE) model. By immunohistochemical analysis of brain sections from kainic acid-induced SE mice, we found that kainic acid greatly enhanced HMGB1 translocation in the hippocampus, which was attenuated by ICM pretreatment in subregion- and cell type-dependent manners. Notably, in CA1 region, the seizure focus, ICM pretreatment mainly inhibited HMGB1 translocation in microglia. Furthermore, the anti-seizure effect of ICM was related to HMGB1 targeting, as pre-injection of anti-HMGB1 monoclonal antibody (5 mg/kg, i.p.) blocked the seizure-suppressing effect of ICM in kainic acid-induced SE model. In addition, ICM pretreatment significantly alleviated pyramidal neuronal loss and granule cell dispersion in kainic acid-induced SE model. These results demonstrate that ICM is an HMGB-targeting small molecule with anti-seizure potential, which may help develop a potential drug for treating epilepsy.

Enhanced Wound Healing Potential of Spirulina platensis Nanophytosomes: Metabolomic Profiling, Molecular Networking, and Modulation of HMGB-1 in an Excisional Wound Rat Model.

Excisional wounds are considered one of the most common physical injuries. This study aims to test the effect of a nanophytosomal formulation loaded with a dried hydroalcoholic extract of S. platensis on promoting excisional wound healing. The Spirulina platensis nanophytosomal formulation (SPNP) containing 100 mg PC and 50 mg CH exhibited optimum physicochemical characteristics regarding particle size (598.40 ± 9.68 nm), zeta potential (-19.8 ± 0.49 mV), entrapment efficiency (62.76 ± 1.75%), and Q6h (74.00 ± 1.90%). It was selected to prepare an HPMC gel (SPNP-gel). Through metabolomic profiling of the algal extract, thirteen compounds were identified. Molecular docking of the identified compounds on the active site of the HMGB-1 protein revealed that 12,13-DiHome had the highest docking score of -7.130 kcal/mol. SPNP-gel showed higher wound closure potential and enhanced histopathological alterations as compared to standard (MEBO® ointment) and S. platensis gel in wounded Sprague-Dawley rats. Collectively, NPS promoted the wound healing process by enhancing the autophagy process (LC3B/Beclin-1) and the NRF-2/HO-1antioxidant pathway and halting the inflammatory (TNF-, NF-κB, TlR-4 and VEGF), apoptotic processes (AIF, Caspase-3), and the downregulation of HGMB-1 protein expression. The present study's findings suggest that the topical application of SPNP-gel possesses a potential therapeutic effect in excisional wound healing, chiefly by downregulating HGMB-1 protein expression.

Lavender essential oil accelerates lipopolysaccharide-induced chronic wound healing by inhibiting caspase-11-mediated macrophage pyroptosis.

Chronic wounds seriously affect the quality of life of the elderly, obese people, and diabetic patients. The excessive inflammatory response is a key driver of delayed chronic wound healing. Although lavender essential oil (EO [lav]) has been proven to have anti-inflammatory and accelerate wound curative effects, the specific molecular mechanism involved is still ambiguous. The results showed that the wounds treated with lipopolysaccharide (LPS) not only had delayed healing, but also the expression levels of pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1ß (IL-1ß), and the inflammatory mediator protein, high-mobility group box 1 protein (HMGB-1), in the wound tissues were significantly increased. However, treatment of LPS-induced chronic wounds with EO (lav) accelerated wound healing and decreased IL-1ß and HMGB-1 expression levels. It was further found that LPS induced macrophage pyroptosis to produce IL-1ß. After treatment with EO (lav), the expression level of macrophage pyroptosis marker Gasdermin D (GSDMD) and pyroptosis-related cytotoxic effects were significantly reduced. Immunofluorescence results also directly indicate that EO (lav) can protect macrophages from LPS-induced pyroptosis. Moreover, EO (lav) can down-regulate expression levels of IL-1ß, GSDMD, and nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) in the caspase-11-related pyroptotic signaling pathway. This study demonstrates that EO (lav) can reduce proinflammatory factor production and ameliorate inflammatory response by inhibiting macrophage pyroptosis, which accelerates LPS-induced chronic wound healing.

Upregulated miR-194-5p suppresses retinal microvascular endothelial cell dysfunction and mitigates the symptoms of hypertensive retinopathy in mice by targeting SOX17 and VEGF signaling.

BACKGROUND: Hypertensive retinopathy (HR) is a retinal disease that may lead to vision loss and blindness. Sex-determining region Y (SRY)-box (SOX) family transcription factors have been reported to be involved in HR development. In this study, the role and upstream mechanism of SRY-box transcription factor 17 (SOX17) in HR pathogenesis were investigated. METHODS: SOX17 and miR-194-5p levels in Angiotensin II (Ang II)-stimulated human retinal microvascular endothelial cells (HRMECs) and retinas of mice were detected by RT-qPCR. SOX17 protein level as well as levels of tight junction proteins and vascular endothelial growth factor (VEGF) signaling-associated proteins were quantified by western blotting. Tube formation assays were performed to evaluate angiogenesis in HRMECs. The structure of mouse retinal tissues was observed by H&E staining. The interaction between miR-194-5p and SOX17 was confirmed by a luciferase reporter assay. RESULTS: SOX17 was upregulated in HRMECs treated with Ang II. SOX17 knockdown inhibited angiogenesis in Ang II-stimulated HRMECs and increased tight junction protein levels. Mechanically, SOX17 was targeted by miR-194-5p. Moreover, miR-194-5p upregulation restrained angiogenesis and increased tight junction protein levels in Ang II-treated HRMECs, and the effect was reversed by SOX17 overexpression. MiR-194-5p elevation inactivated VEGF signaling via targeting SOX17. miR-194-5p alleviated pathological symptoms of HR in Ang II-treated mice, and its expression was negatively correlated with SOX17 expression in the retinas of model mice. CONCLUSIONS: MiR-194-5p upregulation suppressed Ang II-stimulated HRMEC dysfunction and mitigates the symptoms of HR in mice by regulating the SOX17/VEGF signaling.

Effects of an Omega-3 Supplemented, High-Protein Diet in Combination with Vibration and Resistance Exercise on Muscle Power and Inflammation in Old Adults: A Pilot Randomized Controlled Trial.

BACKGROUND: Inflammaging is considered to drive loss of muscle function. Omega-3 fatty acids exhibit anti-inflammatory properties. Therefore, we examined the effects of eight weeks of vibration and home-based resistance exercise combined with a whey-enriched, omega-3-supplemented diet on muscle power, inflammation and muscle biomarkers in community-dwelling old adults. METHODS: Participants were randomized to either exercise (3x/week, n = 20), exercise + high-protein diet (1.2-1.5 g/kg, n = 20), or exercise + high-protein and omega-3-enriched diet (2.2 g/day, n = 21). Muscle power (watt/m2) and chair rise test (CRT) time (s) were assessed via CRT measured with mechanography. Furthermore, leg strength (kg/m2) and fasting concentrations of inflammatory (interleukin (IL-) 6, IL-10, high-mobility group box-1 (HMGB-1)) and muscle biomarkers (insulin-like growth factor (IGF-) 1, IGF-binding protein-3, myostatin) were assessed. RESULTS: Sixty-one participants (70.6 ± 4.7 years; 47% men) completed the study. According to generalized linear mixed models, a high-protein diet improved leg strength and CRT time. Only IGF-1 increased with additional omega-3. Sex-specific analyses revealed that muscle power, IL-6, IL-6/IL-10 ratio, and HMGB-1 improved significantly in the male high-protein, omega-3-enriched group only. CONCLUSION: Vibration and home-based resistance exercise combined with a high-protein, omega-3-enriched diet increased muscle power and reduced inflammation in old men, but not in old women. While muscle biomarkers remained unchanged, a high-protein diet combined with exercise improved leg strength and CRT time.

Tumor-targeting oxidative stress nanoamplifiers as anticancer nanomedicine with immunostimulating activity.

Compared to normal cells, cancer cells are more susceptible to insults of prooxidants that generate ROS (reactive oxygen species) or scavenge antioxidants such as glutathione (GSH). Cancer cells undergo immunogenic cell death (ICD) by elevated oxidative stress. Herein, we report rationally designed F-ssPBCA nanoparticles as a tumor-targeting prooxidant, which generates ROS and scavenges GSH simultaneously to cooperatively amplify oxidative stress, leading to ICD. Prooxidant F-ssPBCA nanoparticles are composed of a disulfide-bridged GSH scavenging dimeric prodrug (ssPB) that self-assembles to form nanoconstructs and encapsulates ROS-generating BCA (benzoyloxy cinnamaldehyde). F-ssPBCA nanoparticles significantly elevate oxidative stress to kill cancer cells and also evoke ICD featured by the release of CRT (calreticulin), HMGB-1 (high mobility group box-1), and adenosine triphosphate (ATP). Animal studies revealed that F-ssPBCA nanoparticles accumulate in tumors preferentially and suppress tumor growth effectively. The results of this study demonstrate that prooxidant-mediated oxidative stress elevation is a highly effective strategy to kill cancer cells selectively and even evoke abundant ICD. We anticipate that oxidative stress amplifying F-ssPBCA nanoparticles hold tremendous translational potential as a tumor targeted ICD-inducing anticancer nanomedicine.

Potential neurotoxic activity of diverse molecules released by astrocytes.

Astrocytes are the main support cells of the central nervous system. They also participate in neuroimmune reactions. In response to pathological and immune stimuli, astrocytes transform to reactive states characterized by increased release of inflammatory mediators. Some of these molecules are neuroprotective and inflammation resolving while others, including reactive oxygen species (ROS), nitric oxide (NO), matrix metalloproteinase (MMP)- 9, L-glutamate, and tumor necrosis factor α (TNF), are well-established toxins known to cause damage to surrounding cells and tissues. We hypothesized that similar to microglia, the brain immune cells, reactive astrocytes can release a broader set of diverse molecules that are potentially neurotoxic. A literature search was conducted to identify such molecules using the following two criteria: 1) evidence of their expression and secretion by astrocytes and 2) direct neurotoxic action. This review describes 14 structurally diverse molecules as less-established astrocyte neurotoxins, including C-X-C motif chemokine ligand (CXCL)10, CXCL12/CXCL12(5-67), FS-7-associated surface antigen ligand (FasL), macrophage inflammatory protein (MIP)- 2α, TNF-related apoptosis inducing ligand (TRAIL), pro-nerve growth factor (proNGF), pro-brain-derived neurotrophic factor (proBDNF), chondroitin sulfate proteoglycans (CSPGs), cathepsin (Cat)B, group IIA secretory phospholipase A2 (sPLA2-IIA), amyloid beta peptides (Aß), high mobility group box (HMGB)1, ceramides, and lipocalin (LCN)2. For some of these molecules, further studies are required to establish either their direct neurotoxic effects or the full spectrum of stimuli that induce their release by astrocytes. Only limited studies with human-derived astrocytes and neurons are available for most of these potential neurotoxins, which is a knowledge gap that should be addressed in the future. We also summarize available evidence of the role these molecules play in select neuropathologies where reactive astrocytes are a key feature. A comprehensive understanding of the full spectrum of neurotoxins released by reactive astrocytes is key to understanding neuroinflammatory diseases characterized by the adverse activation of these cells and may guide the development of novel treatment strategies.

Two hydroxyflavanones isolated from Scutellaria baicalensis roots prevent colitis-associated colon cancer in C57BL/6 J mice by inhibiting programmed cell death-1, interleukin 10, and thymocyte selection-associated high mobility group box proteins TOX/TOX2.

BACKGROUND: Colorectal cancer was the second leading cause of mortality in 2019 and the number of new colorectal cancer cases was the highest in 2018 and 2019 in Japan. PURPOSE: The present study investigated the inhibitory effects of 2(S)-2',5,6',7-tetrahydroxyflavanone and 2 (R), 3(R)-2',3,5,6'-7-pentahydroxyflavanone on the incidence and growth of tumors in azoxymethane (AOM) plus dextran sulfate sodium (DSS)-treated mice. METHODS: The intraperitoneal administration of AOM (10 mg/kg) on day 0 induced colorectal carcinogenesis. Mice were given free and unlimited access to drinking water containing 1.5% (w/v) DSS on days 5 - 8, 30 - 33, and 56 - 57. They were orally administered tetra- and penta-hydroxyflavanones (10 and 30 mg/kg) for 10, 11, and 14 days followed by discontinuation intervals of 20 and 15 days. Cytokine, chemokine, programmed cell death-1 (PD-1), cyclooxygenase (COX)-2, and thymocyte selection-associated high mobility group box protein (TOX)/TOX2 expression levels were measured using their respective ELISA kits and an immunohistochemical analysis. RESULTS: The number and area of tumors decreased by 60.6 and 72.9% in mice administered 10 mg/kg tetra- and pentahydroxyflavanones, respectively, with reductions of 95.0 and 87.0% in Ki-67-positive cells, 91.7 and 92.7% in COX-2-postive cells, and 83.1 and 93.8% in TOX/TOX2-positive cells, respectively, in the colon. On the other hand, two tera- and pentahydroxyflavanone had no effect on p53 (a tumor suppressor by cell cycle arrest and apoptosis)-positive cells. The administration of 10 mg/kg tetra- and pentahydroxyflavanones to AOM/DSS-treated mice also resulted in decreases of 59.5 and 42.5% in IL-10 levels and 58.1 and 93.9% in PD-1 levels, respectively, in the colon. CONCLUSION: The inhibitory effects of tetra- and pentahydroxyflavanones on the growth of colon tumors in AOM/DSS-treated mice appear to be associated with decreases in the colon levels of IL-10 and PD-1 through the down-regulated expression of COX-2 and CD8+ T-cell exhaustion by TOX/TOX2 in the tumor microenvironment.

SOX17 inhibits proliferation and invasion of neuroblastoma through CXCL12/CXCR4 signaling axis.

SOX17 has been shown to be involved in the transcriptional regulation of CXCR4, and CXCL12 functions by binding to its receptor CXCR4. Here, we explored the expression of SOX17 in neuroblastoma (NB), its mutual regulation with CXCL12, and its effects on cancer cell proliferation, migration and invasion. Five human NB cell lines and 15 pairs of NB and adjacent tissue specimens were used, to conduct RT-qPCR, immunohistochemistry, western blot, ELISA, CCK-8, colony formation, Edu, transwell, chromatin immunoprecipitation (ChIP), and dual-luciferase assays, to study the role of SOX17 in NB. SOX17 levels were reduced in both NB tissues and cell lines. SOX17 inhibited NB tumor growth, migration and invasion in vivo and suppressed NB cell proliferation, migration, and invasion in vitro. SOX17 knockdown or overexpression revealed a negative correlation between SOX17 and CXCL12/CXCR4 pathway activation. ChIP and dual-luciferase assays in NB cells demonstrated that SOX17 significantly inhibited CXCL12 gene and protein levels by binding to CXCL12 promoter regions. In vivo and in vitro experiments using the CXCR4 antagonist, AMD3100, demonstrated that cell proliferation, migration and invasion were significantly abrogated by AMD3100 in NB cells with SOX17 knocked down. Further, AMD3100 impaired growth of NB tumors with SOX17 knocked down in mice. Importantly, SOX17 bound to the CXCL12 promoter, which then activated downstream targets to regulate cell viability, proliferation, and migration. In conclusion, our data demonstrate that SOX17 expression is repressed in NB tissues and cells, and that SOX17 suppresses NB tumor formation and proliferation through inhibition of CXCL12/CXCR4 signaling.

Overexpression of Trypanosoma cruzi High Mobility Group B protein (TcHMGB) alters the nuclear structure, impairs cytokinesis and reduces the parasite infectivity.

Kinetoplastid parasites, included Trypanosoma cruzi, the causal agent of Chagas disease, present a unique genome organization and gene expression. Although they control gene expression mainly post-transcriptionally, chromatin accessibility plays a fundamental role in transcription initiation control. We have previously shown that High Mobility Group B protein from Trypanosoma cruzi (TcHMGB) can bind DNA in vitro. Here, we show that TcHMGB also acts as an architectural protein in vivo, since the overexpression of this protein induces changes in the nuclear structure, mainly the reduction of the nucleolus and a decrease in the heterochromatin:euchromatin ratio. Epimastigote replication rate was markedly reduced presumably due to a delayed cell cycle progression with accumulation of parasites in G2/M phase and impaired cytokinesis. Some functions involved in pathogenesis were also altered in TcHMGB-overexpressing parasites, like the decreased efficiency of trypomastigotes to infect cells in vitro, the reduction of intracellular amastigotes replication and the number of released trypomastigotes. Taken together, our results suggest that the TcHMGB protein is a pleiotropic player that controls cell phenotype and it is involved in key cellular processes.

Damage-associated molecular patterns stimulate interleukin-33 expression in nasal polyp epithelial cells.

BACKGROUND: Chronic rhinosinusitis with nasal polyps (CRSwNP) is a disorder characterized by eosinophilic inflammation and local T-helper 2 (Th2) cytokine production. Innate lymphoid cells that elaborate Th2 cytokines have recently been characterized within nasal polyps. These cells can be activated by the epithelial cell-derived cytokine interleukin-33 (IL-33). The objective of this study is to determine whether 2 molecules associated with tissue damage (high mobility group box-1 [HMGB-1] and adenosine triphosphate [ATP]) elicit expression of IL-33 in sinonasal epithelial cells (SNECs) derived from recalcitrant CRSwNP patients. METHODS: Ethmoid tissue was obtained from 8 recalcitrant CRSwNP and 9 control subjects during endoscopic sinus surgery (ESS). Tissue was prepared for immunohistochemistry and for SNEC air-liquid interface culture. After exposure to either HMGB1 or ATP in vitro, SNECs were processed for messenger RNA (mRNA) extraction and immunocytochemistry. IL-33 levels were determined by real-time polymerase chain reaction (PCR) and by immunochemical staining with anti-IL-33 antibody. RESULTS: Intranuclear IL-33 is normally expressed in basal epithelial cells, but is present in more apical cells and outside the nucleus in CRSwNP. Exposure of SNECs to HMGB-1 or ATP resulted in a statistically significant increase in IL-33 mRNA expression in SNECs derived from recalcitrant CRSwNP patients. This increase was reflected at the protein level by immunochemical staining of IL-33. CONCLUSION: Tissue damage is a nonspecific trigger of epithelial IL-33 production in treatment-recalcitrant polyps, which may be responsible for perpetuating eosinophilic inflammation in CRSwNP. This common pathway may help explain why multiple environmental and infectious agents have been implicated in CRSwNP exacerbation.

Programmed necrosis induced by asbestos in human mesothelial cells causes high-mobility group box 1 protein release and resultant inflammation.

Asbestos carcinogenesis has been linked to the release of cytokines and mutagenic reactive oxygen species (ROS) from inflammatory cells. Asbestos is cytotoxic to human mesothelial cells (HM), which appears counterintuitive for a carcinogen. We show that asbestos-induced HM cell death is a regulated form of necrosis that links to carcinogenesis. Asbestos-exposed HM activate poly(ADP-ribose) polymerase, secrete H(2)O(2), deplete ATP, and translocate high-mobility group box 1 protein (HMGB1) from the nucleus to the cytoplasm, and into the extracellular space. The release of HMGB1 induces macrophages to secrete TNF-alpha, which protects HM from asbestos-induced cell death and triggers a chronic inflammatory response; both favor HM transformation. In both mice and hamsters injected with asbestos, HMGB1 was specifically detected in the nuclei, cytoplasm, and extracellular space of mesothelial and inflammatory cells around asbestos deposits. TNF-alpha was coexpressed in the same areas. HMGB1 levels in asbestos-exposed individuals were significantly higher than in nonexposed controls (P < 0.0001). Our findings identify the release of HMGB1 as a critical initial step in the pathogenesis of asbestos-related disease, and provide mechanistic links between asbestos-induced cell death, chronic inflammation, and carcinogenesis. Chemopreventive approaches aimed at inhibiting the chronic inflammatory response, and especially blocking HMGB1, may decrease the risk of malignant mesothelioma among asbestos-exposed cohorts.

Xenopus XsalF: anterior neuroectodermal specification by attenuating cellular responsiveness to Wnt signaling.

Here we show that XsalF, a frog homolog of the Drosophila homeotic selector spalt, plays an essential role for the forebrain/midbrain determination in Xenopus. XsalF overexpression expands the domain of forebrain/midbrain genes and suppresses midbrain/hindbrain boundary (MHB) markers and anterior hindbrain genes. Loss-of-function studies show that XsalF is essential for the expression of the forebrain/midbrain genes and for the repression of the caudal genes. Interestingly, XsalF functions by antagonizing canonical Wnt signaling, which promotes caudalization of neural tissues. XsalF is required for anterior-specific expressions of GSK3beta and Tcf3, genes encoding antagonistic effectors of Wnt signaling. Loss-of-function phenotypes of GSK3beta and Tcf3 mimic those of XsalF while injections of GSK3beta and Tcf3 rescue loss-of-function phenotypes of XsalF. These findings suggest that the forebrain/midbrain-specific gene XsalF negatively controls cellular responsiveness to posteriorizing Wnt signals by regulating region-specific GSK3beta and Tcf3 expression.