High mobility group box 1 in the central nervous system:regeneration hidden beneath inflammation

High-mobility group box 1 was first discovered in the calf thymus as a DNA-binding nuclear protein and has been widely studied in diverse fields,including neurology and neuroscience.High-mobility group box 1 in the extracellular space functions as a pro-inflammatory damage-associated molecular pattern,which has been proven to play an important role in a wide variety of central nervous system disorders such as ischemic stroke,Alzheimer’s disease,frontotemporal dementia,Parkinson’s disease,multiple sclerosis,epilepsy,and traumatic brain injury.Several drugs that inhibit high-mobility group box 1 as a damage-associated molecular pattern,such as glycyrrhizin,ethyl pyruvate,and neutralizing anti-high-mobility group box 1 antibodies,are commonly used to target high-mobility group box 1 activity in central nervous system disorders.Although it is commonly known for its detrimental inflammatory effect,high-mobility group box 1 has also been shown to have beneficial pro-regenerative roles in central nervous system disorders.In this narrative review,we provide a brief summary of the history of high-mobility group box 1 research and its characterization as a damage-associated molecular pattern,its downstream receptors,and intracellular signaling pathways,how high-mobility group box 1 exerts the repair-favoring roles in general and in the central nervous system,and clues on how to differentiate the pro-regenerative from the pro-inflammatory role.Research targeting high-mobility group box 1 in the central nervous system may benefit from differentiating between the two functions rather than overall suppression of high-mobility group box 1.

Hmo1:A versatile member of the high mobility group box family of chromosomal architecture proteins

Eukaryotic chromatin consisting of nucleosomes connected by linker DNA is organized into higher order structures,which is facilitated by linker histone H1.Formation of chromatin compacts and protects the genome,but also hinders DNA transactions.Cells have evolved mechanisms to modify/remodel chromatin resulting in chromatin states suitable for genome functions.The high mobility group box(HMGB)proteins are non-histone chromatin architectural factors characterized by one or more HMGB motifs that bind DNA in a sequence nonspecific fashion.They play a major role in chromatin dynamics.The Saccharomyces cerevisiae(yeast hereafter)HMGB protein Hmo1 contains two HMGB motifs.However,unlike a canonical HMGB protein that has an acidic C-terminus,Hmo1 ends with a lysine rich,basic,C-terminus,resembling linker histone H1.Hmo1 exhibits characteristics of both HMGB proteins and linker histones in its multiple functions.For instance,Hmo1 promotes transcription by RNA polymerases I and II like canonical HMGB proteins but makes chromatin more compact/stable like linker histones.Recent studies have demonstrated that Hmo1 destabilizes/disrupts nucleosome similarly as other HMGB proteins in vitro and acts to maintain a common topological architecture of genes in yeast genome.This minireview reviews the functions of Hmo1 and the underlying mechanisms,highlighting recent discoveries.

Suppressing high mobility group box-1 release alleviates morphine tolerance via the adenosine5'-monophosphate-activated protein kinase/heme oxygenase-1 pathway

Opioids,such as morphine,are the most potent drugs used to treat pain.Long-term use results in high tolerance to morphine.High mobility group box-1(HMGB1) has been shown to participate in neuropathic or inflammatory pain,but its role in morphine tolerance is unclear.In this study,we established rat and mouse models of morphine tolerance by intrathecal injection of morphine for 7 consecutive days.We found that morphine induced rat spinal cord neurons to release a large amount of HMGB1.HMGB1 regulated nuclear factor κB p65 phosphorylation and interleukin-1β production by increasing Toll-like receptor 4receptor expression in microglia,thereby inducing morphine tolerance.Glycyrrhizin,an HMGB1 inhibito r,markedly attenuated chronic morphine tole rance in the mouse model.Finally,compound C(adenosine 5’-monophosphate-activated protein kinase inhibitor) and zinc protoporphyrin(heme oxygenase-1 inhibitor)alleviated the morphine-induced release of HMGB1 and reduced nuclear factor κB p65 phosphorylation and interleukin-1β production in a mouse model of morphine tolerance and an SH-SY5Y cell model of morphine tole rance,and alleviated morphine tolerance in the mouse model.These findings suggest that morphine induces HMGB1 release via the adenosine 5’-monophosphate-activated protein kinase/heme oxygenase-1 signaling pathway,and that inhibiting this signaling pathway can effectively reduce morphine tole rance.

The Expression and Functional Analysis of the Gene At2G34450 in High Mobility Group B Proteins from Arabidopsis thaliana

[Objective]To better understand the functions of High Mobility Group B （HMGB） proteins in the transcriptional regulation of plant stress responses.[Method]We cloned the At2G33450 gene encoding At2G34450 protein in Arabidopsis thaliana.Binary vectors carrying the above gene were transformed into Arabidopsis to detect the influences of environmental stimuli to transgenic Arabidopsis.[Result] Under salt or drought stress the transgenic Arabidopsis plants over-expressed At2G33450 displayed retarded germination and subsequent growth compared with wild-type plants.[Conclusion]Our results provide a novel basis for understanding the biological functions of HMGB protein family members that differently affect germination and seedling growth of Arabidopsis plants under various stress conditions.

Expression and Purification of Arabidopsis High Mobility Group B Protein Gene At2G34450 in Pichia pastoris

[Objective] The aim was to study the expression of Arabidopsis gene A/2G34450 in Pichia pastoris and to obtain recombinant Arabidopsis HMGB protein. [Method] The At2G34450 gene was cloned into yeast expression vector pPIC9K containing AOXl promoter and the sequences of secreting α-signal peptides. Recombinant plasmid was linearized by Sal l and transformed into P. pastoris GSl15 competent cells by electroporation. Positive integrated clones were screened out, and the At2G34450 protein was expressed under the induction of methanol. [Result] The At2G34450 protein was expressed in yeast medium through methanol induction. SDS-PAGE results showed that recombination product was At2G34450 protein. [Conclusion] At2G34450 protein was successfully expressed in the P. pastoris system for the first time, which paves a direct path to further research on the functions of HMGB family members.

High mobility group box-1 protein inhibits regulatory T cell immune activity in liver failure in patients with chronic hepatitis B

BACKGROUND: Liver failure in chronic hepatitis B (CHB) patients is a severe, life-threatening condition. Intestinal endotoxemia plays a significant role in the progress to liver failure. High mobility group box-1 (HMGB1) protein is involved in the process of endotoxemia. Regulatory T (Treg) cells maintain immune tolerance and contribute to the immunological hyporesponsiveness against HBV infection. However, the roles of HMGB1 and Treg cells in the pathogenesis of liver failure in CHB patients, and whether HMGB1 affects the immune activity of Treg cells are poorly known at present, and so were explored in this study. METHODS: The levels of HMGB1 expression were detected by ELISA, real-time RT-PCR, and Western blotting, and the percentage of CD4(+)CD25(+)CD127(low) Treg cells among CD4(+) cells was detected by flow cytometry in liver failure patients with chronic HBV infection, CHB patients, and healthy controls. Then, CD4(+)CD25(+)CD127(low) Treg cells isolated from the peripheral blood mononuclear cells from CHB patients were stimulated with HMGB1 at different concentrations or at various intervals. The effect of HMGB1 on the immune activity of Treg cells was assessed by a suppression assay of the allogeneic mixed lymphocyte response. The levels of forkhead box P3 (Foxp3) expression in Treg cells treated with HMGB1 were detected by RT-PCR and Western blotting. RESULTS: A higher level of HMGB1 expression and a lower percentage of Treg cells within the population of CIA(+) cells were found in liver failure patients than in CHB patients (82.6+/-20.1 mu g/L vs. 34.2+/-13.7 mu g/L; 4.55+/-1.34% vs. 9.52+/-3.89%, respectively). The immune activity of Treg cells was significantly weakened and the levels of Foxp3 expression were reduced in a dose- or time-dependent manner when Treg cells were stimulated with HMGB1 in vitro. CONCLUSIONS: The high level of HMGB1 and the low percentage of Treg cells play an important role in the pathogenesis of liver failure in patients with chronic HBV infection. Moreover, HMGB1 can weaken the immune activity of Treg cells. It is suggested that effectively inhibiting HMGB1 expression could be a feasible way to treat liver failure by suppressing endotoxemia and enhancing Treg cell activity.

Blockade of high mobility group box-1 protein attenuates experimental severe acute pancreatitis

AIM： To examine the effects of anti-high mobility group box 1 （HIGB1） neutralizing antibody in experimental severe acute pancreatitis （SAP）. METHODS： SAP was induced by creating closed duodenal loop inC3H/HeN mice. SAP was induced immediately after intrapedtoneal injection of anti-HMGB1 neutralizing antibody （200 pg）. Sevedty of pancreatitis, organ injury （liver, kidney and lung）, and bacterial translocation to pancreas was examined 12 h after induction of SAP. RESULTS： Anti-HHGB1 neutralizing antibody significantly improved the elevation of the serum amylase level and the histological alterations of pancreas and lung in SAR Anti-HHGB1 antibody also significantly ameliorated the elevations of serum alanine aminotransferase and creatinine in SAR However, anti-HHGB1 antibody worsened the bacterial translocation to pancreas. CONCLUSION： Blockade of HHGB1 attenuated the development of SAP and associated organ dysfunction, suggesting that HHGB1 may act as a key mediator for inflammatory response and organ injury in SAR

Delayed ethyl pyruvate therapy attenuates experimental severe acute pancreatitis via reduced serum high mobility group box 1 levels in rats

AIM： To investigate the effect of delayed ethyl pyruvate （EP） delivery on distant organ injury, survival time and serum high mobility group box 1 （HMGB1） levels in rats with experimental severe acute pancreatitis （SAP）. METHODS： A SAP model was induced by retrograde injection of artificial bile into the pancreatic ducts of rats. Animals were divided randomly into three groups （n = 32 in each group）： sham group, SAP group and delayed EP treatment group. The rats in the delayed EP treatment group received EP （30 mg/kg） at 12 h, 18 h and 30 h after induction of SAP. Animals were sacrificed, and samples were obtained at 24 h and 48 h after induction of SAP. Serum HMGB1, aspartate arninotransferase （AST）, alanine arninotransferase （ALT）, blood urea nitrogen （BUN）, and creatinine （Cr） levels were measured. Lung wet-to-dry-weight （W/D） ratios and histological scores were calculated to evaluate lung injury. Additional experiments were performed between SAP and delayed EP treatment groups to study the influence of EP on survival times of SAP rats. RESULTS： Delayed EP treatment significantly reduced serum HMGB1 levels, and protected against liver, renal and lung injury with reduced lung W/D ratios （8.22 ±0.42 vs 9.76 ± 0.45, P 〈 0.01）, pulmonary histological scores （7.1 ± 0.7 vs 8.4 ± 1.1, P 〈 0.01）, serum AST （667 ± 103 vs 1 368 ± 271, P 〈 0.01）, ALT （446 ± 91 vs 653 ± 98, P 〈 0.01） and Cr （1.2 ± 0.3 vs 1.8 ± 0.3, P 〈 0.01） levels. SAP rats had a median survival time of 44 h. Delayed EP treatment significantly prolonged median survival time to 72 h （P 〈 0.01）. CONCLUSION： Delayed EP therapy protects against distant organ injury and prolongs survival time via reduced serum HMGBllevels in rats with experimental SAP. EP may potentially serve as an effective new therapeutic option against the inflammatory response and multiple organ dysfunction syndrome （MODS） in SAP patients.

Novel insights for high mobility group box 1 proteinmediated cellular immune response in sepsis:A systemic review

High mobility group box 1 protein （HMGB1） is a highly conserved, ubiquitous protein in the nuclei and cytoplasm of nearly all cell types. HMGB1 is secreted into the extracellular milieu and acts as a proinflammatory cytokine. In this article we reviewed briefly the cellular immune response mediated by HMGB1 in inflammation and sepsis. This systemic review is mainly based on our own work and other related reports HMGB1 can actively affect the immune functions of many types of cells including T lymphocytes, regulatory T cells （Tregs）, dendritic cells （DCs）, macrophages, and natural killer cells （NK cells）. Various cellular responses can be mediated by HMGB1 which binds to cell-surface receptors [e.g., the receptor for advanced glycation end products （RAGE）, Toll-like receptor （TLR）2, and TLR4]. Anti-HMGB1 treatment, such as anti-HMGB1 polyclonal or monoclonal antibodies, inhibitors （e.g., ethyl pyruvate） and antagonists （e.g., A box）, can protect against sepsis lethality and give a wider window for the treatment opportunity. HMGB1 is an attractive target for the development of new therapeutic strategies in the treatment of patients with septic complications.

Effect on proliferation and apoptosis of retinoblastoma cell by RNA inhibiting high mobility group protein box-1 expression

AIM： To investigate the effect of high mobility group protein box-1 （HMGB1） siRNA on proliferation and apoptosis of retinoblastoma （Rb） cells.METHODS： The expression of HMGB1 in Rb cells were detected by real-time polymerase chain reaction （RT-PCR） and Western blot. Chemically synthesized HMGB1 siRNA was transfected into Y79 cells. The inhibitory rate was also examined by RT-PCR and Western blot. After HMGB1 siRNA transfection, the cell proliferation was analyzed by MTT, and cell apoptosis was detected by Caspase-3 active detection kit. Cell cycle distribution and apoptosis were detected by flow cytometry. RESULTS： The expression of HMGB1 significantly elevated in Rb cells （P〈0.01）. After transfected by siRNA, the HMGB1 protein level of Y79 cells was significantly reduced （P〈0.01）. After siRNA interference HMGB1, the proportion of proliferating cells reduced, and the proportion of quiescent cells increased （P〈0.05）. In addition, apoptosis rate of Y79 cells increased from 2.03% to 9.10% after interfering with HMGB1 siRNA （P〈0.05）.CONCLUSION： Specific HMGB1 siRNA can inhibit the expression of HMGB1. The effect may be attributed to inhibit the proliferation and promote cell apoptosis.

Inflammatory response and immune regulation of high mobility group box-1 protein in treatment of sepsis

Sepsis is an infection induced systemic inflammatory response syndrome and is a major cause of morbidity as well as mortality in intensive care units. A growing body of evidence suggests that the activation of a proinflammatory cascade is responsible for the development of immune dysfunction, susceptibility to severe sepsis and septic shock. The present theories of sepsis as a dysregulated inflammatory response and immune function, as manifested by excessive release of inflammatory mediators such as high mobility group box 1 protein （HMGB1）, are supported by increasing studies employing animal models and clinical observations of sepsis. HMGB1, originally described as a DNA-binding protein and released passively by necrotic cells and actively by macrophages/monocytes, has been discovered to be one of essential cytokines that mediates the response to infection, injury and inflammation. A growing number of studies still focus on the inflammation-regulatory function and its contribution to infectious and inflammatory disorders, recent data suggest that HMGB1 formation can also markedly influence the host cell-mediated immunity, including T lymphocytes and macrophages. Here we review emerging evidence that support extracellular HMGB1 as a late mediator of septic complications, and discuss the therapeutic potential of several HMGBl-targeting agents in experimental sepsis. In addition, with the development of traditional Chinese medicine in recent years, it has been proven that traditional Chinese herbal materials and their extracts have remarkable effective in treating severe sepsis. In this review, we therefore provide some new concepts of HMGBl-targeted Chinese herbal therapies in sepsis.

High mobility group box 1 protein(HMGB1)as an immune-modulating factor for polarization of human T lymphocytes

Objective This study was performed to investigate the effect of high mobility group box-1 protein(HMGB1)on immune function of human T lymphocytes in vitro and explore its potential role in cell-mediated immune dysfunction.Methods Fresh blood was obtained from healthy adult volunteers and peripheral blood mononuclear cells(PBMCs)were isolated,then rhHMGB1 was added to PBMCs.Four-color flow cytometric(FCM)analysis was used for the measurement of intracellular cytokine including interleukin IL-4 and interferon IFN-?ELISA kits were employed for the determination of IL-2 and sIL-2R protein levels in cell culture supernatants.Results(1)Different stimulating time and dosage of rhHMGB1 did not alter the number of IFN-αpositive cells(Th1).rhHMGB1 stimulation provoked a dose-dependent and time-dependent increase in Th2 subset and decrease in ratio of Th1 to Th2.(2)Compared with the untreated cells,when the cells were coincubated with rhHMGB1(10-100ng/ml)for 12 hrs,protein release of IL-2 and sIL-2R were significantly up-regulated.At 48 hrs,in contrast,protein production was relatively lower in cells after exposure to 100-1000 ng/ml rhHMGB1.Conclusions These findings demonstrated that HMGB1 has a dual influence on immune functions of human T lymphocytes.

Changes of High Mobility Group box 1 in Serum of Pig Acute Hepatic Failure Model and Significance

The role of the high mobility group box 1 （HMGB-1） in acute hepatic failure and the effect of artificial liver support system treatment on HMGB-1 level were investigated. Pig models of acute hepatic failure were induced by D-galactosamine and randomly divided into two groups with or without artificial liver support system treatment. Tumor necrosis factor-α （TNF-α） and interleukin-1β （IL-1β） levels were detected by the enzyme linked immunosorbent assay （ELISA）, the expression of HMGB-1 by Western blot, and serum levels of HMGB-1, liver function and hepatic pathology were observed after artificial liver support system treatment. The levels of TNF-α and IL-1β were increased and reached the peak at 24th h in the acute hepatic failure group, then quickly decreased. The serum level of HMGB-1 was increased at 24th h in the acute hepatic failure group and reached the peak at 48th h, then kept a stable high level. Significant liver injury appeared at 24th h and was continuously getting worse in the pig models of acute hepatic failure. In contrast, the liver injury was significantly alleviated and serum level of HMGB-1 was significantly decreased in the group treated with artificial liver support system （P〈0.05）. It was suggested that HMGB-1 may participate in the inflammatory response and liver injury in the late stage of the acute liver failure. Artificial liver support system treatment can reduce serum HMGB-1 level and relieve liver pathological damage.

Association between thrombomodulin and high mobility group box 1 in sepsis patients

BACKGROUND High mobility group box 1(HMGB1)has been studied as a molecule associated with severe outcomes in sepsis and thrombomodulin(TM)seems to decrease HMGB1 activity.AIM To investigate the role of the thrombomodulin/high mobility group box 1(T/H)ratio in patients with sepsis and their association with their clinic,testing the hypothesis that higher ratios are associated with better outcomes.METHODS Twenty patients diagnosed with sepsis or septic shock,according to the 2016 criteria sepsis and septic shock(Sepsis-3),were studied.Patients were followed until they left the intensive care unit or until they achieved 28 d of hospitalization(D28).The following clinical outcomes were observed:Sequential Organ Failure Assessment(SOFA)score;Need for mechanical pulmonary ventilation;Presence of septic shock;Occurrence of sepsis-induced coagulopathy;Need for renal replacement therapy(RRT);and Death.RESULTS The results showed that patients with SOFA scores greater than or equal to 12 points had higher serum levels of TM:76.41±29.21 pg/mL vs 37.41±22.55 pg/mL among those whose SOFA scores were less than 12 points,P=0.003.The T/H ratio was also higher in patients whose SOFA scores were greater than or equal to 12 points,P=0.001.The T/H ratio was,on average,three times higher in patients in need of RRT(0.38±0.14 vs 0.11±0.09),P<0.001.CONCLUSION Higher serum levels of TM and,therefore,higher T/H ratio in the first 24 h after the diagnosis of sepsis were associated with more severe disease and the need for renal replacement therapy,while those with better clinical outcomes and those who were discharged before D28 showed a tendency for lower T/H ratio values.

Role of high mobility group box protein 1 in depression:A mechanistic and therapeutic perspective

As a common and serious psychiatric disorder,depression significantly affects psychosocial functioning and quality of life.However,the mechanism of depression is still enigmatic and perplexing,which limits its precise and effective therapeutic methods.Recent studies demonstrated that neuroinflammation activation plays an important role in the pathophysiology of depression.In this respect,high mobility group box 1(HMGB1)may be a possible signaling inducer of neuroinflammation and can be a potential mechanistic and therapeutic target for depression.Herein,we review recent studies on the mechanistic and therapeutic targets of HMGB1 in depression and propose potential perspectives on this topic.

Effects of Ethyl Pyruvate on High Mobility Group Box1 gene expression in septic lung of rat

Objective: Ethyl Pyruvate (EP) has been shown to be an effective anti-inflammatory agent in a variety of model systems. The aim of this study was to investigate the effects of EP on High Mobility Group Box1(HMGB1) genes expression and the possible mechanisms of EP protecting against acute lung injury induced by sepsis. Methods: Forty Wistar rats were randomly divided into normal controls,sham operation,acute lung injury,and EP treatment (40 mg/kg intra-peritoneally every 6 hrs) groups. At the time points of 24 hours the animals in each group were sacrificed, and the lungs were harvested. Wet/dry lung weight ratio, the protein in the bronchoalveolar lavage fluid(BALF),and pulmonary permeability index(PPI) were determined. The histological morphology of lung was observed under microscope. The expression of HMGB1 mRNA was measured using semi-quantitative RT-PCR. Results: EP treatment decreased wet/dry lung weight ratio, the protein in the BALF,and PPI (P<0.01). The histological morphology of lung injury was ameliorated. EP significantly inhibited the HMGB1 mRNA expression(P<0.01). HMGB1 mRNA expression in lungs positively correlation with wet/dry lung weight ratio, the protein in the BALF,and PPI. Conclusion: EP administered inhibits HMGB1 mRNA expression, and protects the lungs against acute injury induced by sepsis.

Relationship of plasma homocysteine, soluble intercellular adhesion molecule-1, high mobility group box 1 protein with carotid intima-media thickness in elderly patients with type 2 diabetes mellitus

Objective:To explore the relationship of plasma homocysteine(Hcy),soluble intercellular adhesion molecule-1(sICAM-1)and high mobility group box 1 protein(HMGB1)with carotid intima-media thickness(c-IMT)in elderly patients with type 2 diabetes mellitus.Methods:A total of 100 elderly patients who were diagnosed as type 2 diabetes mellitus in Baogang Hospital of Inner Mongolia from June 2017 to May 2020 were chosen as research objects.According to c-IMT,they were divided into the normal group(n=35),the mild to moderate group(n=41)and the severe group(n=24).The expression levels of plasma Hcy,sICAM-1 and HMGB1 were compared between groups respectively.Pearson’s correlation coefficient was used to analyze the relationship of plasma Hcy,sICAM-1,HMGB1 with c-IMT.Results:The comparison in plasma Hcy,sICAM-1,HMGB1 and c-IMT among the three groups of patients was of statistical significance(p<.05).The results of correlation analysis showed that the expression levels of plasma Hcy,sICAM-1 and HMGB1 were positively correlated with c-IMT in elderly patients with type 2 diabetes mellitus(r=.627,.598,.614;p<.05).Conclusions:The expression levels of plasma Hcy,sICAM-1 and HMGB1 are abnormally increased in elderly patients with type 2 diabetes mellitus,and related to c-IMT,which can provide a strong evidence for clinical diagnosis and treatment by detecting their levels in clinical practice.

Effect of silencing of high mobility group A2 gene on gastric cancer MKN-45 cells

AIM:To investigate the effect of high mobility group A2(HMGA2) gene silencing on gastric cancer MKN-45 cells in vitro.METHODS:HMGA2 short hairpin RNA(shRNA) expression plasmids were constructed,including a pair of random scrambled sequences.Human gastric cancer cell line MKN-45 cells were divided into three groups:blank control group(non-transfected cells),transfected group(cells transfected with HMGA2 shRNA recombinant plasmid) and scrambled sequence group(transfected with random scrambled plasmid).Cells were transfected with HMGA2 shRNA recombinant plasmids and scrambled plasmid in vitro,and the cells transfection efficiency was assayed by fluorescence microscopy.The HMGA2 messenger RNA(mRNA) expression was detected by reverse transcription polymerase chain reaction,gastric cancer cells apoptosis was detected by flow cytometry,cell proliferation was detected by methyl thiazol tetrazolium,and the protein expression of phosphatidylinositol 3-kinase(PI3K),protein kinase B(Akt),P27,caspase-9 and B-cell leukemia/lymphoma-2(Bcl-2) were analyzed by Western blotting.RESULTS:Compared with the blank control group and the scrambled sequence group,the levels of HMGA2 mRNA and protein expression in the transfected group were significantly reduced(P < 0.05).The relative HMGA2 mRNA expression levels of the blank control group,transfected group and scrambled sequence group were 0.674 ± 0.129,0.374 ± 0.048 and 0.689 ± 0.124,respectively.The relative HMGA2 protein expression levels of the blank control group,transfected group and scrambled sequence group were 0.554 ± 0.082,0.113 ± 0.032 and 0.484 ± 0.123,respectively.Moreover,transfection with the scrambled sequence had no effect on the expression of HMGA2.After being transfected with shRNA for 24,48 and 72 h,the cell apoptotic rates of the transfected group were 21.65% ± 0.28%,39.98% ± 1.82% and 24.51% ± 0.93%,respectively,which significantly higher than those of blank control group(4.72% ± 1.34%,5.83% ± 0.13% and 5.22% ± 1.07%) and scrambled sequence group(4.28% ± 1.33%,7.87% ± 1.43% and 6.71% ± 0.92%).After 24,48 and 72 h,the cell proliferation inhibition rates in the transfected group were 31.57% ± 1.17%,39.45% ± 2.07% and 37.56% ± 2.32%,respectively;the most obvious cell proliferation inhibition appeared at 48 h after transfection.Compared with the blank control group and scrambled sequence group,after transfection of shRNA for 72 h,the protein expression levels of PI3K(0.042 ± 0.005 vs 0.069 ± 0.003,0.067 ± 0.05),Akt(0.248 ± 0.004 vs 0.489 ± 0.006,0.496 ± 0.104) and Bcl-2(0.295 ± 0.084 vs 0.592 ± 0.072,0.594 ± 0.109) were significantly reduced.The protein expression levels of P27(0.151 ± 0.010 vs 0.068± 0.014,0.060 ± 0.013) and caspase-9(0.136 ± 0.042 vs 0.075 ± 0.010,0.073 ± 0.072) were significantly upregulated.CONCLUSION:HMGA2 shRNA gene silencing induces apoptosis and suppresses proliferation of MKN-45 cells.

High mobility group protein 1: A collaborator in nucleosome dynamics and estrogen-responsive gene expression

High mobility group protein 1(HMGB1) is a multifunctional protein that interacts with DNA and chromatin to influence the regulation of transcription, DNA replication and repair and recombination. We show that HMGB1 alters the structure and stability of the canonical nucleosome(N) in a nonenzymatic,adenosine triphosphate-independent manner. As a result, the canonical nucleosome is converted to two stable, physically distinct nucleosome conformers. Although estrogen receptor(ER) does not bind to its consensus estrogen response element within a nucleosome, HMGB1 restructures the nucleosome to facilitate strong ER binding. The isolated HMGB1-restructured nucleosomes(N' and N'') remain stable and exhibit a number of characteristics that are distinctly different from the canonical nucleosome. These findings complement previous studies that showed(1) HMGB1 stimulates in vivo transcriptional activation at estrogen response elements and(2) knock down of HMGB1 expression by siR NA precipitously reduced transcriptional activation. The findings indicate that a major facet of the mechanism of HMGB1 action involves a restructuring of aspects of the nucleosome that appear to relax structural constraints within the nucleosome. The findings are extended to reveal the differences between ER and the other steroid hormone receptors. A working proposal outlines mechanisms that highlight the multiple facets that HMGB1 may utilize in restructuring the nucleosome.

Expression of high mobility group protein B1 in the lungs of rats with sepsis

BACKGROUND： Vibrio vulnifi cus inside the body could activate the NF-!B signaling pathwayand initiate the inflammatory cascade. The lung is one of the earliest organs affected by sepsisassociated with acute lung injury. High mobility group protein B1 （HMGB1） is an important late-actingpro-infl ammatory cytokine involving in the pathophysiology of sepsis. It is also involved in the injuryprocess in the lung, liver and intestine. There has been no report on the involvement of HMGB1 inVibrio vulnifi cus sepsis-induced lung injury.METHODS： Sixty rats were randomly divided into a normal control group （group A, n=10） anda Vibrio vulnificus sepsis group （group B, n=50）. Sepsis was induced in the rats by subcutaneousinjection of Vibrio vulnificus （concentration 6×108 cfu/mL, volume 0.1 mL/100g）） into the left lowerlimbs. The rats in group B were sacrifi ced separately 1, 6, 12, 24, and 48 hours after the infection.Their lungs were stored as specimens, lung water content was measured, and lung pathology wasobserved under a light microscope. The expressions of the HMGB1 gene and protein in the lungswere detected by RT-PCR and Western blot. Data were analyzed with one-way analysis of variance（ANOVA） and the LSD method for pair-wise comparison between the two groups. P〈0.05 wasconsidered statistically signifi cant.RESULTS： Compared to group A （0.652±0.177）, HMGB1 mRNA expression in the lungs ofgroup B was signifi cantly higher at 0 hour （1.161±0.358, P=0.013）, 24 hours （1.679±0.235, P=0.000）,and 48 hours （1.258±0.274, P=0.004） （P〈0.05）, and peaked at 24 hours. Compared to group A（0.594±0.190）, HMGB1 protein expression at 6 hours （1.408±0.567, P=0.026） after infection wassignificantly increased （P〈0. 05）, and peaked at 24 hours （2.415±1.064, P=0.000） after infection.Compared to group A （0.699±0.054）, lung water content was significantly increased at 6 hours（0.759±0.030, P=0.001）,12 hours （0.767±0.023, P=0.000）, 24 hours （0.771±0.043, P=0.000） and 48hours （0.789±0.137, P=0.000） after infection （P〈0.05）. Compared to group A, pathological changesat 12 hours in group B indicate marked pulmonary vascular congestion, interstitial edema andinfl ammatory infi ltration. Alveolar cavity collapse and boundaries of the alveolar septum could not beclearly identifi ed.CONCLUSION： Vibrio vulnifi cus sepsis can lead to injury in rat lungs, and increased HMGB1expression in lung tissue may be one of the mechanisms for injury from Vibrio vulnifi cus sepsis.