mRNA Levels Of HMGB1 Research Articles

Magnesium deficiency promotes secretion of high-mobility group box 1 protein from lipopolysaccharide-activated macrophages in vitro

BackgroundHigh-mobility group box 1 (HMGB1) is a critical mediator of sepsis that is closely related to sepsis lethality. Magnesium deficiency predisposes to worse outcomes from endotoxin challenge by promoting the production of cytokines. However, whether magnesium deficiency affects the expression and release of HMGB1 is not currently known. In the present study, we explored the effect of magnesium deficiency on the expression and secretion of HMGB1 in lipopolysaccharide (LPS)-activated RAW264.7 macrophages. MethodsRAW264.7 cells were incubated with LPS in normal magnesium (1 mmol/L magnesium sulfate) or low magnesium (0.1 mmol/L magnesium sulfate) in Roswell Park Memorial Institute 1640 medium. An enzyme-linked immunosorbent assay was used to detect HMGB1 levels in the culture supernatant. Real-time polymerase chain reaction was used to assess the HMGB1 mRNA levels. A nuclear/cytoplasm extraction kit was used to extract the nuclear and cytoplasmic proteins. Western blotting was used to observe the changes in translocation of HMGB1 from the nucleus to the cytoplasm. A nuclear factor κ-light chain enhancer of activated B cells (NF-κB) p50/p65 transcription factor assay kit was used to analyze the NF-κB activity in nuclear extracts. ResultsMagnesium deficiency promoted translocation of HMGB1 from the nucleus to the cytoplasm and its extracellular secretion in LPS-activated macrophages, while enhancing the expression of HMGB1 mRNA. Furthermore, magnesium deficiency promoted the translocation of NF-κB from the cytoplasm to the nucleus in LPS-activated macrophages. ConclusionsMagnesium deficiency promotes the translocation of HMGB1 from the nucleus to the cytoplasm and the expression of HMGB1 mRNA. Magnesium deficiency also activates the NF-κB signaling pathway.

HMGB1 regulates autophagy through increasing transcriptional activities of JNK and ERK in human myeloid leukemia cells

HMGB1 is associated with human cancers and is an activator of autophagy which mediates chemotherapy resistance. We here show that the mRNA levels of HMGB1 are high in leukemia cells and it is involved in the progression of childhood chronic myeloid leukemia (CML). HMGB1 decreases the sensitivity of human myeloid leukemia cells K562 to anti-cancer drug induced death through up-regulating the autophagy pathway, which is confirmed by the observation with an increase in fusion of autophagosomes and autophagolysosomes. When overexpressing HMGB1, both mRNA levels of Beclin-1, VSP34 and UVRAG which are key genes involved in mammalian autophagy and protein levels of p-Bcl-2 and LC3-II are increased. Luciferase assays document that over-expression of HMGB1 increases the transcriptional activity of JNK and ERK, which may be silenced by siRNA. The results suggest that HMGB1 regulates JNK and ERK required for autophagy, which provides a potential drug target for therapeutic interventions in childhood CML.

Differential expression of wheat genes during cold acclimation

Overwintering crops such as winter wheat display significant increase in freezing tolerance during a period of cold acclimation (CA). To gain better understanding of molecular mechanisms of CA, it is important to unravel functions and regulations of CA-associated genes. Differential screening of a cDNA library constructed from cold acclimated crown tissue of winter wheat identified three novel CA-associated cDNA clones. Nucleotide sequence analysis showed that the clones encode a high mobility globular protein (HMGB1), a glycine-rich RNA-binding protein (TaGRP2), and a LEA D-11 dehydrin (DHN14). Accumulation of the three mRNAs during 14 days of CA was differentially regulated. In response to drought, and ABA, DHN14 mRNA rapidly accumulated while HMGB1 and TaGRP2 mRNA levels remained unchanged. The possible functions of each of these genes in cold acclimation are discussed.

The potential mechanism on signal transduction pathway in regulation of mRNA expression of high mobility group box-1 protein in septic rats

To investigate the potential role of Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway in regulation of gene expression of high mobility group box-1 protein (HMGB1) in various tissues in rats with sepsis. A sepsis model reproduced by cecal ligation and puncture (CLP), and 128 male Wistar rats were randomly divided into normal control group (n = 10), sham operation group (n = 10), CLP group (n = 60), AG490 treatment group (n = 24), and rapamycin (RPM) treatment group (n = 24). At serial time points animals in each group were sacrificed after CLP, then tissue samples were harvested to determine HMGB1 mRNA expression and STAT1/3 DNA binding activity. STAT1 activities increased rapidly in the liver, lungs and small intestine after CLP, peaking at 6 - 12 h, while it increased slowly, and still kept at mild level from 2 to 48 h in the kidneys. Compared with STAT1, lower STAT3 activities were detected only in the liver and lungs, with negative detection in the small intestine and kidneys. HMGB1 mRNA levels significantly increased in liver, lungs and small intestine at various time points after CLP respectively (P < 0.05 or P < 0.01), while they didn't change in the kidneys. Treatment with AG490 could markedly inhibit HMGB1 mRNA expression in the liver and small intestine at 24 and 48 h (P < 0.05 or P < 0.01), and in lungs at 2 h following CLP (P < 0.01). Similarly, treatment with RPM significantly decreased HMGB1 mRNA expression in the lungs at 2, 6, 24 and 48 h, in the liver at 6 and 24 h, and in the small intestine at 24 and 48 h (P < 0.05 or P < 0.01). In addition, STAT1 and STAT3 activities in the liver and lungs were significantly correlated with corresponding tissue HMGB1 mRNA expression. Peritoneal infection could extensively activate STAT1 and limitedly activate STAT3 in vital organs. Activation of JAK/STAT pathway might be involved in up-regulating the gene expression of HMGB1 and systemic inflammation secondary to severe septic challenge.