Hmo1 Promotes Efficient Transcription Elongation by RNA Polymerase I in Saccharomyces cerevisiae

RNA polymerase I (Pol I) is responsible for synthesizing the three largest eukaryotic ribosomal RNAs (rRNAs), which form the backbone of the ribosome. Transcription by Pol I is required for cell growth and, therefore, is subject to complex and intricate regulatory mechanisms. To accomplish this robust regulation, the cell engages a series of trans-acting transcription factors. One such factor, high mobility group protein 1 (Hmo1), has long been established as a trans-acting factor for Pol I in Saccharomyces cerevisiae; however, the mechanism by which Hmo1 promotes rRNA synthesis has not been defined. Here, we investigated the effect of the deletion of HMO1 on transcription elongation by Pol I in vivo. We determined that Hmo1 is an important activator of transcription elongation, and without this protein, Pol I accumulates across rDNA in a sequence-specific manner. Our results demonstrate that Hmo1 promotes efficient transcription elongation by rendering Pol I less sensitive to pausing in the G-rich regions of rDNA.

Determination of HMGB1 in hepatitis B virus-related acute-on-chronic liver failure patients with acute kidney injury: Early prediction and prognostic implications

Background: Acute kidney injury (AKI) is a frequent complication in patients with hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) and is associated with high rates of mortality. We aimed to estimate serum high mobility group protein 1 (HMGB1) levels in hepatitis B virus-related acute-on-chronic liver failure patients and analyze their clinical value in the development and outcomes of Acute kidney injury. Methods: A total of 251 consecutive patients with hepatitis B virus-related acute-on-chronic liver failure were enrolled in this retrospective study. Using the International Club of Ascites staging criteria of Acute kidney injury, 153 patients developed Acute kidney injury. The clinical data of patients were collected and serum levels of high mobility group protein 1 were measured by ELISA. All patients were followed up until death or for a minimum of 3 months. Early prediction and prognostic implications of high mobility group protein 1 in Hepatitis B Virus-Related Acute-on-Chronic Liver Failure Patients with Acute Kidney Injury were investigated in different cohorts, including a propensity score-matched ACLF cohort. Results: Among all individuals with hepatitis B virus-related acute-on-chronic liver failure, the incidence of Acute kidney injury was 61.0% (153/251). The patients who developed stage 2/3 Acute kidney injury showed the highest high mobility group protein 1 levels, followed by those who developed stage 1 Acute kidney injury, and those without Acute kidney injury showed the lowest high mobility group protein 1 levels. Moreover, high mobility group protein 1 levels were significantly higher in non-survivors than in survivors among hepatitis B virus-related acute-on-chronic liver failure patients with Acute kidney injury. Furthermore, analysis of the area under the receiver operating characteristic curve (AUROC) indicated that serum high mobility group protein 1 levels (pre-matching: AUC = 0.740; post-matching: AUC = 0.661) may be a potential predictive factor for Acute kidney injury development and that high mobility group protein 1 (AUC = 0.727) might be a reliable biomarker for prognosis in patients with Acute kidney injury. Conclusion: In patients with hepatitis B virus-related acute-on-chronic liver failure, Acute kidney injury is universal. Acute kidney injury and its stages negatively influence the 90-day transplant-free mortality rate. Serum high mobility group protein 1 levels can serve as a positive predictor of Acute kidney injury development, and high mobility group protein 1 might also be a prognostic biomarker for Acute kidney injury among hepatitis B virus-related acute-on-chronic liver failure patients.

circ‑LRP6 contributes to osteosarcoma progression by regulating the miR‑141‑3p/HDAC4/HMGB1 axis

Circular RNA-lipoprotein receptor 6 (circ-LRP6) serves a role in promoting the tumorigenesis of retinoblastoma, esophageal squamous cell cancer and oral squamous cell carcinoma; however, whether circ-LRP6 demonstrates the same effect in osteosarcoma (OS) is yet to be fully elucidated. The present study aimed to analyze the expression, role and potential molecular mechanism of circ-LRP6 in OS. The expression levels of circ-LRP6, microRNA (miR)-141-3p, histone deacetylase 4 (HDAC4) and high mobility group protein 1 (HMGB1) were evaluated by reverse transcription- quantitative PCR in OS tissues and cell lines. Cell Counting Kit-8, Transwell and Matrigel assays were conducted to evaluate cell proliferation, migration and invasion, respectively. Western blotting was also performed to determine HDAC4 and HMGB1 protein expression levels. Bioinformatics and dual-luciferase reporter assays were used to predict and analyze the interactions between circ-LRP6 and miR-141-3p, miR-141-3p and HDAC4, as well as between miR-141-3p and HMGB1. Additionally, RNA immunoprecipitation was performed to verify the association between circ-LRP6 and miR-141-3p. The results confirmed that circ-LRP6 was highly expressed in OS tissues and cell lines. In addition, circ-LRP6 negatively regulated the expression of miR-141-3p and, in turn, miR-141-3p negatively regulated HDAC4 and HMGB1 expression. Functional assays revealed that circ-LRP6 knockdown inhibited the proliferation, migration and invasion of OS cells, whereas the inhibition of miR-141-3p or the overexpression of either HDAC4 or HMGB1 partly reversed the inhibitory effect of circ-LRP6 knockdown. In summary, the present study determined that circ-LRP6 knockdown inhibited the proliferation, migration and invasion of OS cells by regulating the miR-141-3p/HDAC4/HMGB1 axis.

[Mechanism of high expression of high mobility group protein 1 in a rat model of knee osteoarthritis]

OBJECTIVE

To investigate the molecular mechanism triggering pyroptosis of synovial fibroblast-like synoviocytes(FLSs)and the release of high mobility group protein 1(HMGB1)in a rat model of knee osteoarthritis(KOA).

METHODS

Twelve SD rats were randomized equally into blank control group without any treatment and KOA group with anterior cruciate ligament amputation (ACLT) to induce KOA.HE staining and Mankin score were used to evaluate the damage of knee cartilage.Western blotting was used to detect the expression of pyroptosis-related proteins and HMGB1 in the synovial tissue.In the cell experiment, rat FLSs were treated with PBS (control group), LPS+ATP (to induce cell pyroptosis), or LPS+ATP+siRNAs (to inhibit pyroptosis of the FLSs), and the cellular expressions of apoptosis-related proteins and HMGB1 were detected using Western blotting; the level of HMGB1 in the culture supernatant was detected with ELISA.

RESULTS

In the rat models of KOA, the expressions of pyroptosis-related proteins and HMGB1 in the synovial tissue and Mankin score were significantly increased as compared with those in the control group(P < 0.05).In cultured rat FLSs, the expressions of apoptosis related proteins and HMGB1 were significantly higher in the pyroptosis group than in the control group and in cells transfected with the siRNAs targeting NLRP1, NLRP3, ASC and caspase-1(P < 0.05).The protein level of HMGB1 in the culture supernatant was significantly higher in pyroptosis group than in the control and siRNA groups (P < 0.05).

CONCLUSION

In the pathological process of KOA, NLRPs inflammasome-mediated FLS pyroptosis causes massive release of HMGB1, which is associated with the activation of the downstream molecule caspase-1.

Clinical effect of Changweishu on gastrointestinal dysfunction in patients with sepsis

Objective

To investigate Changweishu’s clinical effect on gastrointestinal dysfunction in patients with sepsis.

Methods

Fifty patients with gastrointestinal dysfunction and sepsis were randomly divided into treatment and control groups. The control group patients received routine Western medicine treatments (meropenem, noradrenaline, glutamine glue, Bifidobacterium lactis triple-strain tablet), and the treatment group patients received routine Western medicine treatment combined with Changweishu. Treatments in both groups lasted 7 days. Changes in APACHE II score, gastrointestinal dysfunction score, serum levels of diamine oxidase (DAO), D-lactic acid, inflammatory factors (tumor necrosis factor (TNF)-α, interleukin (IL)-6, and high-mobility group box 1 (HMGB-1)), and the incidence of multiple organ dysfunction syndrome (MODS) and mortality were observed.

Results

After treatment, APACHE II score, gastrointestinal dysfunction score, and DAO, D-lactic acid, TNF-α, IL-6, and HMGB-1 levels decreased significantly in both groups, but the decrease was more significant in the treatment group than in the control group. The incidence of MODS and mortality were significantly lower in the treatment group than in the control group.

Conclusion

The addition of Changweishu to routine Western treatments can improve gastrointestinal function in patients with sepsis and gastrointestinal dysfunction, as well as decreasing the incidence of MODS and mortality and improving patient prognosis.

Escin suppresses HMGB1-induced overexpression of aquaporin-1 and increased permeability in endothelial cells

Escin, a natural triterpene saponin mixture obtained from the horse chestnut tree (Aesculus hippocastanum), has been used for the treatment of chronic venous insufficiency (CVI), hemorrhoids, and edema. However, it is unclear how escin protects against endothelial barrier dysfunction induced by pro‐inflammatory high mobility group protein 1 (HMGB1). Here, we report that escin can suppress (a) HMGB1‐induced overexpression of the aquaporin‐1 (AQP1) water channel in endothelial cells and (b) HMGB1‐induced increases in endothelial cell permeability. This is the first report that escin inhibits AQP1 and alleviates barrier dysfunction in HMGB1‐induced inflammatory response.

High Mobility Group Protein 1 Reverses Immune System Paralysis in Late-Phase Sepsis

High mobility group protein 1 (HMGB1) is considered to be the primary inflammatory factor triggering immune paralysis in late-phase sepsis. In this study, however, we wanted to explore the possibility of using HMGB1 to boost local differentiation of bone marrow cells (BMCs) into regulatory dendritic cells (DCs) in vivo, thereby inducing immune reversal in late-phase sepsis and improving the prognosis. For this purpose, sepsis was induced by cecal ligation and puncture (CLP). Mice were injected intraperitoneally with HMGB1 (10, 50, or 250 μg/kg of body weight) 7 days before CLP. BMCs and liver immune cells were isolated at 0, 3, 5, and 7 days post-CLP. Mice were intranasally infected with Pseudomonas aeruginosa 3 days post-CLP as a secondary pneumonia infection model. BMCs and liver cells isolated from septic mice pretreated with HMGB1 were adoptively transferred into CLP mice. GFP⁺-C57BL/6 and C3H/HeN-C3H/HeJ parabiosis models were established. We found that HMGB1 pretreatment improved the survival of sepsis and increased the numbers of BMCs and liver immune cells in CLP mice. Furthermore, HMGB1 stimulation improved survival in the secondary pneumonia infection model. HMGB1 increased the number as well as the percentage of CD11c^- CD45RB^high DCs in septic BM and liver. Adoptive transfer of septic cells pretreated with HMGB1 into CLP mice attenuated sepsis. HMGB1 enhanced the redistribution of CD11c^- CD45RB^high DCs through TLR4 signaling in parabiosis models. We conclude that HMGB1 triggers immune reversal through the mobilization, redistribution, and local immune differentiation of BMCs, thereby compensating for impaired immunity and leading to sufficient bacterial eradication.

Exogenous MSCs ameliorate hypoxia/reoxygenation injury in renal tubular epithelial cells through JAK/STAT signaling pathway-mediated regulation of HMGB1

This study was conducted to investigate the repair mechanism of hypoxia/reoxygenation injury (HRI) in renal tubular epithelial cells (HK-2) by exogenous mesenchymal stem cells (MSCs). The activation of the JAK/STAT pathway in HK-2 cells after HRI and treatment of MSCs, JAK inhibitor WP1066 and STAT inhibitor SOCS3 was investigated using Western blot analysis. HK-2 cells were transfected with siRNA STAT3 and analyzed for expression of STAT3, JAK2 and HMGB1 using fluorescence quantitative PCR and Western blot. Cell viability and apoptosis were analyzed using the MTT assay and flow cytometry. After HRI, the JAK/STAT pathway in HK-2 cells was activated, resulting in the upregulation of JAK1, JAK2, JAK3, p-JAK1, p-JAK2, p-JAK3, STAT1, STAT2, STAT3, p-STAT1, p-STAT2 and p-STAT3. After treatment with MSC conditioned medium (MSCs CM), WP1066, or SOCS, the expression of these proteins was significantly down-regulated. When the cells were transfected with siRNA STAT3, the expression of STAT3 at protein and mRNA levels and JAK2 and HMGB1 at mRNA level was down-regulated; the cell viability was reduced and apoptosis increased. It is concluded that exogenous MSCs reduce HRI of HK-2 cells by suppressing the JAK/STAT signaling pathway and down-regulating the expression of HMGB1.

Expression and cell distribution of receptor for advanced glycation end-products in the rat cortex following experimental subarachnoid hemorrhage

Convincing evidence indicates that inflammation contributes to the adverse prognosis of subarachnoid hemorrhage (SAH). Some pro-inflammatory molecules such as high mobility group protein 1, S100 family of proteins, β-amyloid peptide, and macrophage antigen complex 1 have been involved in the damaging inflammation process following SAH. The receptor for advanced glycation end-products (RAGE) is a transmembrane receptor that senses these molecules and plays central role in inflammatory processes. This study aimed to determine the expression and cell distribution of RAGE in the brain cortex after SAH. Male Sprague-Dawley rats were randomly divided into sham group and SAH groups at 6 h, 12 h and on day 1, day 2 and day 3 (n=6 for each subgroup). SAH groups suffered experimental SAH by injection of 0.3 ml autologous blood into the prechiasmatic cistern. RAGE expression was measured by Western blot, real-time PCR, immunohistochemistry and immunofluorescence. Nuclear expression of p65 protein, the major subunit of nuclear factor kappa B, was also detected. Our data demonstrated that the expression levels of RAGE and nuclear p65 protein were both markedly increased after SAH. Moreover, there was a significant positive correlation between the expression of RAGE and that of p65 protein. Double immunofluorescence staining showed that RAGE was expressed by neuron and microglia rather than astrocyte after SAH. These results suggest that RAGE may be directly involved in the inflammatory response after SAH, and there might be important implications for further studies using specific RAGE antagonists to decrease inflammation-mediated brain injury following SAH.