High-mobility group protein box-1 and its relevance to cerebral ischemia.
Ontology highlight
ABSTRACT:
SUBMITTER: Yang QW
PROVIDER: S-EPMC2949127 | biostudies-other | 2010 Feb
REPOSITORIES: biostudies-other
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Project description:Excessive release of high mobility group box-1 (HMGB1) protein from ischemic cardiomyocytes activates inflammatory cascades and enhances myocardial injury after reperfusion. Here we report evidence that electroacupuncture of mice at Neiguan acupoints can inhibit the up-regulation of cardiac HMGB1 following myocardial ischemia and attenuate the associated inflammatory responses and myocardial injury during reperfusion. These benefits of electroacupuncture were partially reversed by administering recombinant HMGB1 to the mice, and further potentiated by administering anti-HMGB1 antibody. Electroacupuncture-induced inhibition of HMGB1 release was markedly reduced by unilateral vagotomy or administration of nicotinic receptor antagonist, but not by chemical sympathectomy. The cholinesterase inhibitor neostigmine mimicked the effects of electroacupuncture on HMGB1 release and myocardial ischemia reperfusion injury. Culture experiments with isolated neonatal cardiomyocytes showed that acetylcholine, but not noradrenaline, inhibited hypoxia-induced release of HMGB1 via a ?7nAchR-dependent pathway. These results suggest that electroacupuncture acts via the vagal nerve and its nicotinic receptor-mediated signaling to inhibit HMGB1 release from ischemic cardiomyocytes. This helps attenuate pro-inflammatory responses and myocardial injury during reperfusion.
| S-EPMC4620449 | biostudies-literature
Project description:The unicellular eukaryote Entamoeba histolytica is a human parasite that causes amebic dysentery and liver abscess. A genome-wide analysis of gene expression modulated by intestinal colonization and invasion identified an up-regulated transcript that encoded a putative high-mobility-group box (HMGB) protein, EhHMGB1. We tested if EhHMGB1 encoded a functional HMGB protein, and determined its role in control of parasite gene expression. Recombinant EhHMGB1 was able to bend DNA in vitro, a characteristic of HMGB proteins. Core conserved residues required for DNA bending activity in other HMGB proteins were demonstrated by mutational analysis to be essential for EhHMGB1 activity. EhHMGB1 was also able to enhance the binding of human p53 to its cognate DNA sequence in vitro, which is expected for an HMGB1 protein. Confocal microscopy, using antibodies against the recombinant protein, confirmed its nuclear localization. Overexpression of EhHMGB1 in HM1: IMSS trophozoites led to modulation of 33 transcripts involved in a variety of cellular functions. Of these, twenty were also modulated at either day one or day 29 in the mouse model of intestinal amebiasis. Notably, four transcripts with known roles in virulence, including two encoding Gal/GalNAc lectin light chains, were modulated in response to EhHMGB1 overexpression. We concluded that EhHMGB1 was a bona fide HMGB protein with the capacity to recapitulate part of the modulation of parasite gene expression seen during adaptation to the host intestine. 6 samples for two groups: 3M and Gir. Each groups contain 3 samples
2008-11-19 | E-GEOD-12204 | biostudies-arrayexpress
Project description:UnlabelledHigh-mobility group box 1 (HMGB1) is an abundant chromatin-associated nuclear protein and released into the extracellular milieu during liver ischemia-reperfusion (I/R), signaling activation of proinflammatory cascades. Because the intracellular function of HMGB1 during sterile inflammation of I/R is currently unknown, we sought to determine the role of intracellular HMGB1 in hepatocytes after liver I/R. When hepatocyte-specific HMGB1 knockout (HMGB1-HC-KO) and control mice were subjected to a nonlethal warm liver I/R, it was found that HMGB1-HC-KO mice had significantly greater hepatocellular injury after I/R, compared to control mice. Additionally, there was significantly greater DNA damage and decreased chromatin accessibility to repair with lack of HMGB1. Furthermore, lack of hepatocyte HMGB1 led to excessive poly(ADP-ribose)polymerase 1 activation, exhausting nicotinamide adenine dinucleotide and adenosine triphosphate stores, exacerbating mitochondrial instability and damage, and, consequently, leading to increased cell death. We found that this was also associated with significantly more oxidative stress (OS) in HMGB1-HC-KO mice, compared to control. Increased nuclear instability led to a resultant increase in the release of histones with subsequently more inflammatory cytokine production and organ damage through activation of Toll-like receptor 9.ConclusionThe lack of HMGB1 within hepatocytes leads to increased susceptibility to cellular death after OS conditions.
| S-EPMC3999251 | biostudies-literature
Project description:Background and aimsSterile inflammation is a major clinical concern during ischemia-reperfusion injury (IRI) triggered by traumatic events, including stroke, myocardial infarction, and solid organ transplantation. Despite high-mobility group box 1 (HMGB1) clearly being involved in sterile inflammation, its role is controversial because of a paucity of patient-focused research.Approach and resultsHere, we examined the role of HMGB1 oxidation states in human IRI following liver transplantation. Portal blood immediately following allograft reperfusion (liver flush; LF) had increased total HMGB1, but only LF from patients with histopathological IRI had increased disulfide-HMGB1 and induced Toll-like receptor 4-dependent tumor necrosis factor alpha production by macrophages. Disulfide HMGB1 levels increased concomitantly with IRI severity. IRI+ prereperfusion biopsies contained macrophages with hyperacetylated, lysosomal disulfide-HMGB1 that increased postreperfusion at sites of injury, paralleling increased histone acetyltransferase general transcription factor IIIC subunit 4 and decreased histone deacetylase 5 expression. Purified disulfide-HMGB1 or IRI+ blood stimulated further production of disulfide-HMGB1 and increased proinflammatory molecule and cytokine expression in macrophages through a positive feedback loop.ConclusionsThese data identify disulfide-HMGB1 as a mechanistic biomarker of, and therapeutic target for, minimizing sterile inflammation during human liver IRI.
| S-EPMC8722704 | biostudies-literature
Project description:The unicellular eukaryote Entamoeba histolytica is a human parasite that causes amebic dysentery and liver abscess. A genome-wide analysis of gene expression modulated by intestinal colonization and invasion identified an up-regulated transcript that encoded a putative high-mobility-group box (HMGB) protein, EhHMGB1. We tested if EhHMGB1 encoded a functional HMGB protein, and determined its role in control of parasite gene expression. Recombinant EhHMGB1 was able to bend DNA in vitro, a characteristic of HMGB proteins. Core conserved residues required for DNA bending activity in other HMGB proteins were demonstrated by mutational analysis to be essential for EhHMGB1 activity. EhHMGB1 was also able to enhance the binding of human p53 to its cognate DNA sequence in vitro, which is expected for an HMGB1 protein. Confocal microscopy, using antibodies against the recombinant protein, confirmed its nuclear localization. Overexpression of EhHMGB1 in HM1: IMSS trophozoites led to modulation of 33 transcripts involved in a variety of cellular functions. Of these, twenty were also modulated at either day one or day 29 in the mouse model of intestinal amebiasis. Notably, four transcripts with known roles in virulence, including two encoding Gal/GalNAc lectin light chains, were modulated in response to EhHMGB1 overexpression. We concluded that EhHMGB1 was a bona fide HMGB protein with the capacity to recapitulate part of the modulation of parasite gene expression seen during adaptation to the host intestine.
2008-11-20 | GSE12204 | GEO
Project description:High mobility group box (HMGB)1 action contributes to late phases of sepsis, but the effects of increased endogenous plasma HMGB1 levels on brain cells during inflammation are unclear. Here, we aimed to further investigate the role of HMGB1 in the brain during septic-like lipopolysaccharide-induced inflammation in rats (LPS, 10 mg/kg, i.p.). HMGB-1 mRNA expression and release were measured in the periphery/brain by RT-PCR, immunohistochemistry and ELISA. In vitro experiments with disulfide-HMGB1 in primary neuro-glial cell cultures of the area postrema (AP), a circumventricular organ with a leaky blood-brain barrier and direct access to circulating mediators like HMGB1 and LPS, were performed to determine the direct influence of HMGB1 on this pivotal brain structure for immune-to-brain communication. Indeed, HMGB1 plasma levels stayed elevated after LPS injection. Immunohistochemistry of brains and AP cultures confirmed LPS-stimulated cytoplasmatic translocation of HMGB1 indicative of local HMGB1 release. Moreover, disulfide-HMGB1 stimulation induced nuclear factor (NF)-κB activation and a significant release of interleukin-6, but not tumor necrosis factor α, into AP culture supernatants. However, only a few AP cells directly responded to HMGB1 with increased intracellular calcium concentration. Interestingly, priming with LPS induced a seven-fold higher percentage of responsive cells to HMGB1. We conclude that, as a humoral and local mediator, HMGB1 enhances brain inflammatory responses, after LPS priming, linked to sustained sepsis symptoms.
| S-EPMC8230749 | biostudies-literature
Project description:Diabetes is a global epidemic and more than 50% diabetic patients are also diagnosed with neuropathy, which greatly affects the quality of life of the patients. Available treatments are not always successful due to the limited efficacy and complications, such as addiction and dependency. Studies have implicated that high mobility group box1 (HMGB1) protein plays a crucial role in neuroinflammation and the development of neuropathic conditions. HMGB1 is a proinflammatory cytokine that can be released from necrotic cells in passive form or in response to inflammatory signals as an active form. HMGB1 is the ligand for the receptor for advanced glycation end products (RAGE), and toll-like receptors, (TLR)-2 and TLR4, which also indirectly activates C-X-C chemokine receptor type 4 (CXCR4). We investigated whether blocking of HMGB1 can reduce pain and inflammation in diabetic neuropathic animals to further understand the role of HMGB1 in diabetic neuropathy. Type 2 diabetic rats and mice were treated with natural inhibitor of HMGB1, glycyrrhizin (GLC) for five days/week for four weeks at a dose of 50 mg/kg per day by intraperitoneal injection. The animals were divided into three categories: naïve control, diabetic alone, diabetic with GLC treatment. All of the behavioral analyses were conducted before and after the treatment. The expression of inflammatory markers and changes in histone acetylation in the peripheral nervous system were measured by immunohistochemistry and Western blot analysis after the completion of the treatment. Our study revealed that TLR4, HMGB1, CXCR4, and Nod-like receptor protein 3 (NLRP3) levels were increased in the spinal and dorsal root ganglia (DRG) neurons of Type 2 diabetic mice and rats with painful neuropathy. GLC treatment inhibited the increases in TLR4, NLRP3, and CXCR4 expressions and improved the mechanical and thermal pain threshold in these animals. Immunohistochemical studies revealed that hyperglycemia mediated inflammation influenced HMGB1 acetylation and its release from the neurons. It also altered histone 3 acetylation in the microglial cells. The inhibition of HMGB1 by GLC prevented the release of HMGB1 as well as H3K9 acetylation. These findings indicate that the interruption of HMGB1 mediated inflammation could ameliorate diabetic neuropathy and might exhibit a unique target for the treatment.
| S-EPMC7036925 | biostudies-literature
Project description:Multiple sclerosis (MS) is an autoimmune, demyelinating disease and as such, the gold standard of treatment is to selectively suppress the pathogenic autoimmune response without compromising the entire arm of the adaptive immune response. One target of this strategy lying upstream of the pathologic adaptive immune response is the local, innate immune signaling that initiates and drives autoimmunity and sterile injury. High-mobility group box 1 protein (HMGB1) is a ubiquitous nuclear protein that when released from necrotic cells, such as damaged oligodendrocytes in MS lesions, drives pro-inflammatory responses. Here we demonstrate that HMGB1 drives neuroinflammatory responses in experimental autoimmune encephalomyelitis (EAE), a murine model for MS, and that inhibition of HMGB1 signaling ameliorates disease. Specifically i.v. injection of an HMGB1 neutralizing antibody in the C57BL/6 model of chronic EAE or SJL/J model of relapsing-remitting EAE ameliorated clinical disease prophylactically or during ongoing disease, blocked T cell infiltration of the central nervous system, and inhibited systemic CD4(+) T cell responses to myelin epitopes. Additionally, lymphocytes from EAE mice restimulated in vitro in the presence of recombinant HMGB1 exhibited increased proliferation and pro-inflammatory cytokine production, an effect that was blocked by anti-HMGB1 antibody. Similarly recombinant HMGB1 promoted proliferation and pro-inflammatory cytokine production of human peripheral blood mononuclear cells stimulated in vitro, and anti-HMGB1 antibody blocked this effect. These findings indicate that HMGB1 contributes to neuroinflammatory responses that drive EAE pathogenesis and that HMGB1 blockade may be a novel means to selectively disrupt the pro-inflammatory loop that drives MS autoimmunity.
| S-EPMC3672339 | biostudies-literature
Project description:High mobility group box 1 (HMGB1) is a nuclear factor that usually binds DNA and modulates gene expression in multicellular organisms. Three HMGB1 orthologs were predicted in the genome of Toxoplasma gondii, an obligate intracellular protozoan pathogen, termed TgHMGB1a, b and c. Phylogenetic and bioinformatic analyses indicated that these proteins all contain a single HMG box and which shared in three genotypes. We cloned TgHMGB1a, a 33.9 kDa protein that can stimulates macrophages to release TNF-α, and, we demonstrated that the TgHMGB1a binds distorted DNA structures such as cruciform DNA in electrophoretic mobility shift assays (EMSA). Immunofluorescence assay indicated TgHMGB1a concentrated in the nucleus of intracellular tachyzoites but translocated into the cytoplasm while the parasites release to extracellular. There were no significant phenotypic changes when the TgHMGB1a B box was deleted, while transgenic parasites that overexpressed TgHMGB1a showed slower intracellular growth and caused delayed death in mouse, further quantitative RT-PCR analyses showed that the expression levels of many important genes, including virulence factors, increased when TgHMGB1a was overexpressed, but no significant changes were observed in TgHMGB1a B box-deficient parasites. Our findings demonstrated that TgHMGB1a is indeed a nuclear protein that maintains HMG box architectural functions and is a potential proinflammatory factor during the T.gondii infection. Further studies that clarify the functions of TgHMGB1s will increase our knowledge of transcriptional regulation and parasite virulence, and might provide new insight into host-parasite interactions for T. gondii infection.
| S-EPMC4219823 | biostudies-literature
Project description:High mobility group box 1 (HMGB1) is an extremely versatile protein that is located predominantly in the nucleus of quiescent eukaryotic cells, where it is critically involved in maintaining genomic structure and function. During cellular stress, however, this multifaceted, cytokine-like protein undergoes posttranslational modifications that promote its translocation to the cytosol, from where it is released extracellularly, either actively or passively, according to cell type and stressor. In the extracellular milieu, HMGB1 triggers innate inflammatory responses that may be beneficial or harmful, depending on the magnitude and duration of release of this pro-inflammatory protein at sites of tissue injury. Heightened awareness of the potentially harmful activities of HMGB1, together with a considerable body of innovative, recent research, have revealed that excessive production of HMGB1, resulting from misdirected, chronic inflammatory responses, appears to contribute to all the stages of tumorigenesis. In the setting of established cancers, the production of HMGB1 by tumor cells per se may also exacerbate inflammation-related immunosuppression. These pro-inflammatory mechanisms of HMGB1-orchestrated tumorigenesis, as well as the prognostic potential of detection of elevated expression of this protein in the tumor microenvironment, represent the major thrusts of this review.
| S-EPMC7407638 | biostudies-literature