Biomedical subjects

Shubing Liu

Publications and source records attributed to Shubing Liu.

6 recordsLinked to original sources

PubMed2007

Early growth response 1 mediates the systemic and hepatic inflammatory response initiated by hemorrhagic shock.

Hemorrhagic shock (HS) is a major cause of morbidity and mortality in trauma patients. The early growth response 1 (Egr-1) transcription factor is induced by a variety of cellular stresses, including hypoxia, and may function as a master switch to trigger the expression of numerous key inflammatory mediators. We hypothesized that HS would induce hepatic expression of Egr-1 and that Egr-1 upregulates the inflammatory response after HS. The Egr-1 mice and wild-type (WT) controls (n>or=5 for all groups) were subjected to HS alone or HS followed by resuscitation (HS/R). Other mice were subjected to a sham procedure which included general anesthesia and vessel cannulation but no shock (sham). After the HS, HS/R, or sham procedures, mice were euthanized for determination of serum concentrations of interleukin (IL) 6, IL-10, and alanine aminotransferase. Northern blot analysis was performed to evaluate Egr-1 messenger RNA (mRNA) expression. Liver whole cell lysates were evaluated for Egr-1 protein expression by Western blot analysis. Hepatic expression of IL-6, granulocyte colony-stimulating factor, and intracellular adhesion molecule 1 mRNA was determined by semiquantitative reverse transcriptase-polymerase chain reaction. The Egr-1 DNA binding was assessed using the electrophoretic mobility shift assay. Hemorrhagic shock results in a rapid and transient hepatic expression of Egr-1 mRNA in WT mice by 1 h, whereas protein and DNA binding activity was evident by 2.5 h. The Egr-1 mRNA expression diminished after 4 h of resuscitation, whereas Egr-1 protein expression and DNA binding activity persisted through resuscitation. The Egr-1 mice exhibited decreased levels of hepatic inflammatory mediators compared with WT controls with a decrease in hepatic mRNA levels of IL-6 by 42%, granulocyte colony-stimulating factor by 39%, and intracellular adhesion molecule 1 by 43%. Similarly, Egr-1 mice demonstrated a decreased systemic inflammatory response and hepatic injury after HS/R compared with their WT counterparts. Early growth response 1 is rapidly upregulated in the liver during and after resuscitation from HS. Our results showing a blunted inflammatory response in Egr-1 mice provides evidence that Egr-1 functions as a proximal signal transduction mechanism responding to shock by amplifying the systemic inflammatory response.

Animals↗

PubMed2006

Development, utilization of introgression lines using a synthetic wheat as donor.

A series of introgression lines (ILs) were generated from repeated backcrossing between the exotic hexaploid wheat genotype Am3 and the common wheat genotype Laizhou953. Am3 was synthesized by crossing Triticum carthlicum with Aegilops tauschii and was used as the donor parent in this study, and Laizhou953 was used as the recurrent parent. Two hundred and five SSR markers showing polymorphism between the two parents were used to identify the introgressed Am3 chromosome segments in 97 BC4F3 ILs. The introgressed segments in each line and the length of the introgressed segments were estimated according to the wheat SSR consensus map. The introgressed segments from Am3 in the 97 lines covers 37.7% of the donor genome. The introgressed segments were most found on 2D, 3B, 6B, and 1D with coverage of 59.8, 59.5, 59.1, and 59% of the chromosomes, respectively. None of the 97 lines tested contained chromosome 4D segments introgressed from Am3. Introgressed segments for each of the chromosomes were mapped using the consensus wheat linkage map. Nine agronomic traits from BC4F3 lines were evaluated and the phenotype showed most lines have the tendency to be more similar to the recurrent parent. There were lines showing better agronomic traits than the recurrent parent, which indicated the introgression of favorable alleles from the exotic hexaploid wheat into the elite cultivar Laizhou953. Marker and phenotype data were used to identify quantitative trait loci (QTLs) controlling these nine traits. In total, 38, 33, and 28 putative QTLs were detected for seven of the nine traits in 2003, 2004, and 2005, respectively. Some of these agronomic important QTLs were detected in more than one season.

Alleles↗

PubMed2005

Hepatocytes enhance effects of lipopolysaccharide on liver nonparenchymal cells through close cell interactions.

The response to lipopolysaccharide (LPS) in the liver is complex, requiring cell-to-cell interactions between hepatocytes and liver nonparenchymal cells (NPC), in particular, Kupffer cells. Previous studies show that cytokines produced by Kupffer cells stimulated with LPS can, in turn, activate hepatocytes. In the present study, we sought to examine whether the reverse, hepatocyte (HC)-NPC interactions, is important in cytokine production in mixed cell cocultures. LPS-stimulated production of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 from NPC was augmented in mixed HC-NPC cocultures, as compared with NPC monocultures. This HC-NPC interaction was not observed when hepatocytes were cocultured with NPC from TLR4-mutant (C3H/HeJ) mice or CD14-deficient mice. The effect was partially lost when hepatocytes from lipopolysaccharide-binding protein (LBP)-deficient mice were cocultured with wild-type mice. These data indicate that functional TLR4 and CD14 are required for NPC production of cytokines and that at least one of the critical components from hepatocytes is LBP. The augmented cytokine production by mixed HC-NPC cocultures was abrogated when the cells were separated by a filter system, indicating that close cell interactions are also required for this interaction. Thus, interaction between hepatocytes and NPC are critical for cytokine secretion by NPC.

Animals↗

PubMed2004

Cytokines increase CRE binding but decrease CRE-mediated reporter activity in rat hepatocytes by increasing c-Jun.

The cyclic AMP response element (CRE) has been implicated in the regulation of the expression of many genes and cellular processes important in hepatocyte function. CRE sites exist in the promoter regions of several genes expressed during inflammation. Numerous studies on the role of CRE in hepatocyte gene expression have been performed in resting hepatocytes, but the role of CRE during inflammation is unknown. To evaluate the regulation of CRE-mediated transcription during sepsis, cultured hepatocytes were exposed to proinflammatory cytokines and lipopolysaccharide (LPS) was injected into rats. Nuclear proteins were collected and CRE binding activity measured by electromobility shift assay (EMSA) using a consensus CRE oligonucleotide. CRE binding activity was increased in vitro by cytokines and in vivo by LPS administration but CRE-dependent reporter activity was decreased by cytokine stimulation. A c-jun N-terminal kinase (JNK) inhibitor reversed the cytokine-induced increase in CRE binding and increased CRE-dependent reporter activity. Supershift assays indicated that cyclic AMP response element binding protein (CREB) and c-Jun proteins were included in the CRE binding complex. CREB induced and c-Jun suppressed reporter activity using a CRE-dependent construct transfected into cultured primary hepatocytes. In conclusion, these data demonstrate that proinflammatory cytokines regulate CRE binding and activity in cultured hepatocytes and suggest that sepsis-induced changes in CRE binding may participate in the cellular response to inflammation.

Animals↗

PubMed2003

Characterization of the expression of inducible nitric oxide synthase in rat and human liver during hemorrhagic shock.

It has been previously shown that the inducible nitric oxide (NO) synthase (iNOS; NOS-2) is elevated after hemorrhage, and that iNOS-derived NO participates in the upregulation of inflammation as well as lung and liver injury postresuscitation from shock. The purpose of this study was to elucidate the time course of iNOS mRNA expression, as well as the cellular and subcellular localization of iNOS protein in the liver posthemorrhage in rats subjected to varying durations of hemorrhagic shock (HS; mean arterial blood pressure [MAP] = 40 mmHg) with or without resuscitation. Expression of iNOS mRNA in rat liver by real-time reverse transcriptase (RT)-PCR demonstrated iNOS upregulation in shocked animals as compared with their sham counterparts as early as 60 min after the initiation of hemorrhage. By 1 h of HS, iNOS protein was detectable in rat liver by immunofluorescence, and this expression increased with time. Immunofluorescence localized iNOS primarily to the hepatocytes, and in particular to hepatocytes in the centrilobular regions. This analysis, confirmed by immunoelectron microscopy, revealed that iNOS colocalizes with catalase, a peroxisomal marker. Furthermore, we determined that iNOS mRNA is detectable by RT-PCR in liver biopsies from human subjects with HS (MAP < 90 mmHg) associated with trauma (n = 18). In contrast, none of the seven nontrauma surgical patients studied had detectable iNOS mRNA in their livers. Collectively, these results suggest that hepatic iNOS expression, associated with peroxisomal localization, is an early molecular response to HS in experimental animals and possibly in human patients with trauma with HS.

Animals↗

PubMed2002

Role of toll-like receptors in changes in gene expression and NF-kappa B activation in mouse hepatocytes stimulated with lipopolysaccharide.

The liver is an important site of host-microbe interaction. Although hepatocytes have been reported to be responsive to lipopolysaccharide (LPS), the global gene expression changes by LPS and mechanism(s) by which LPS stimulates cultured hepatocytes remain uncertain. Cultures of primary mouse hepatocytes were incubated with LPS to assess its effects on the global gene expression, hepatic transcription factors, and mitogen-activated protein (MAP) kinase activation. DNA microarray analysis indicated that LPS modulates the selective expression of more than 80 genes and expressed sequence tags. We have shown previously that hepatocytes express CD14, which is required both for uptake and responsiveness to LPS. In other cells, responsiveness to microbial products requires expression of Toll-like receptors (TLR) and their associated accessory molecules. Hepatocytes expressed TLR1 through TLR9 as well as MyD88 and MD-2 transcripts, as shown by reverse transcriptase PCR analysis, indicating that hepatocytes express all known microbe recognition molecules. The MAP kinase extracellular signal-regulated kinase 1/2 was phosphorylated in response to LPS in mouse hepatocytes, and the levels of phosphorylation were lower in hepatocytes from TLR4-null mice. NF-kappa B activation was reduced in TLR4-mutant or -null hepatocytes compared to control hepatocytes, and this defect was partially restored by adenoviral transduction of mouse TLR4. Thus, hepatocytes respond to nanogram concentrations of LPS through a TLR4 response pathway.

Adaptor Proteins, Signal Transducing↗