Biomedical subjects

Weimin Xiao

Publications and source records attributed to Weimin Xiao.

6 recordsLinked to original sources

PubMed2006

Gene expression profiling in embryonic mouse lenses.

PURPOSE: In this study, we used laser capture microdissection (LCM) and microarray hybridization technology to compare the gene expression profiles of mouse embryonic days 10 and 12 lenses (E10 and E12). METHODS: Lens cells of C57/BL6 mouse embryos at E10 and E12 were harvested using the PixCell II LCM System. Total RNA was extracted, amplified, labeled, and hybridized to the 430 2.0 mouse chip (Affymetrix) according to the manufacturer's instructions. Data extracted from the images were analyzed using different software programs. Regulated expression of selected genes was confirmed by real-time PCR (RT-PCR). RESULTS: Analysis of the microarray data from E10 and E12 lenses identified 1,573 genes that showed a two fold or greater change in expression level. Among these 1,573 genes, 956 genes were downregulated and 617 were upregulated in E12 lenses. In addition to the upregulated expression of beta- and gamma-crystallin genes, genes that regulate the cell cycle showed significant changes of gene expression during the E10 (lens pit) to E12 (primary fiber cell induction) time period. Genes involved in insulin-like growth factor (IGF) signaling and Wnt (a family of secreted glycoproteins related to the Drosophila segment polarity gene, wingless, and to the proto-oncogene, int-1) signaling were also differentially regulated. In particular, positive regulators of Wnt signaling were downregulated and negative regulators were upregulated, indicating that modulation of Wnt signaling is important for normal lens morphogenesis. CONCLUSIONS: Our results provide new information about differential regulation of gene expression during early lens development. Analysis of global gene expression profiles in embryonic mouse lenses has allowed us to identify several molecular pathways that are differentially regulated during early lens development.

Animals↗

PubMed2006

Hydrogen peroxide stimulates macrophages and monocytes to actively release HMGB1.

High mobility group box 1 (HMGB1) can be actively secreted by macrophages/monocytes in response to exogenous and endogenous inflammatory stimuli (such as bacterial endotoxin, TNF-alpha, IL-1, and IFN-gamma) or passively released by necrotic cells and mediates innate and adaptive inflammatory responses to infection and injury. Here, we demonstrated that a reactive oxygen species, hydrogen peroxide (H(2)O(2)), induces active and passive HMGB1 release from macrophage and monocyte cultures in a time- and dose-dependent manner. At nontoxic doses (e.g., 0.0125-0.125 mM), H(2)O(2) induced HMGB1 cytoplasmic translocation and active release within 3-24 h. At higher concentrations (e.g., 0.25 mM), however, H(2)O(2) exhibited cytotoxicity to macrophage and monocyte cell cultures and consequently, triggered active and passive HMGB1 release. In addition, H(2)O(2) stimulated potential interaction of HMGB1 with a nuclear export factor, chromosome region maintenance (CRM1), in macrophage/monocyte cultures. Inhibitors specific for the JNK (SP600125) and MEK (PD98059), but not p38 MAPK (SB203580), abrogated H(2)O(2)-induced, active HMGB1 release. Together, these data establish an important role for oxidative stress in inducing active HMGB1 release, potentially through a MAPK- and CRM1-dependent mechanism.

Animals↗

PubMed2006

Isolation and characterization of Ty1/copia-like retrotransposons in mung bean (Vigna radiata).

Two Ty1/copia-like retrotransposons, RTvr1 and RTvr2, were isolated from mung bean (Vigna radiata (L.) Wilczek) genomic DNA and are the first complete elements of this kind to be reported in this legume. Nucleotide sequence analyses revealed that both elements are AT-rich (60% and 61%, respectively) and are flanked by a target-site duplication of 5 bp. The structures of RTvr1 and RTvr2 are those of typical long terminal repeat retrotransposons. Both transposons were able to produce putative proteins with the domain order of Gag-protease-integrase-reverse transcriptase-RNase H, indicating that RTvr1 and RTvr2 belong to the Ty1/copia-like retrotransposons. Except for a 2,500-bp insertion region in RTvr2, the overall similarity between RTvr1 and RTvr2 is 92%. Dot blots showed that these two retroelements were present at a copy number of 120 per mung bean haploid genome. Multiple sequence alignments showed that the conserved motifs of the aspartic proteases, integrase, reverse transcriptase, and the RNase H in the Ty1/copia-like group all exist in RTvr1 and RTvr2.

Amino Acid Sequence↗

PubMed2005

Role of Smac/DIABLO in hydrogen peroxide-induced apoptosis in C2C12 myogenic cells.

Smac/DIABLO was recently identified as a protein released from mitochondria in response to apoptotic stimuli which promotes apoptosis by antagonizing inhibitors of apoptosis proteins. Furthermore, Smac/DIABLO plays an important regulatory role in the sensitization of cancer cells to both immune-and drug-induced apoptosis. However, little is known about the role of Smac/DIABLO in hydrogen peroxide (H(2)O(2))-induced apoptosis of C2C12 myogenic cells. In this study, Hoechst 33258 staining was used to examine cell morphological changes and to quantitate apoptotic nuclei. DNA fragmentation was observed by agarose gel electrophoresis. Intracellular translocation of Smac/DIABLO from mitochondria to the cytoplasm was observed by Western blotting. Activities of caspase-3 and caspase-9 were assayed by colorimetry and Western blotting. Full-length Smac/DIABLO cDNA and antisense phosphorothioate oligonucleotides against Smac/DIABLO were transiently transfected into C2C12 myogenic cells and Smac/DIABLO protein levels were analyzed by Western blotting. The results showed that: (1) H(2)O(2) (0.5 mmol/L) resulted in a marked release of Smac/DIABLO from mitochondria to cytoplasm 1 h after treatment, activation of caspase-3 and caspase-9 4 h after treatment, and specific morphological changes of apoptosis 24 h after treatment; (2) overexpression of Smac/DIABLO in C2C12 cells significantly enhanced H(2)O(2)-induced apoptosis and the activation of caspase-3 and caspase-9 (P<0.05). (3) Antisense phosphorothioate oligonucleotides against Smac/DIABLO markedly inhibited de novo synthesis of Smac/DIABLO and this effect was accompanied by decreased apoptosis and activation of caspase-3 and caspase-9 induced by H(2)O(2) (P<0.05). These data demonstrate that H(2)O(2) could result in apoptosis of C2C12 myogenic cells, and that release of Smac/DIABLO from mitochondria to cytoplasm and the subsequent activation of caspase-9 and caspase-3 played important roles in H(2)O(2)-induced apoptosis in C2C12 myogenic cells.

Animals↗

PubMed2005

Heat shock response inhibits release of high mobility group box 1 protein induced by endotoxin in murine macrophages.

The purpose of this study was to evaluate the kinetic changes and the localization of high-mobility group box 1 protein (HMGB1) and to observe the effect of heat shock response (HSR) on the expression and release of HMGB1 in lipopolysaccharide (LPS)-activated murine macrophage-like RAW 264.7 cells. Reverse transcriptase (RT)-PCR and Western blot were used to examine HMGB1 expression after LPS treatment. The intracellular localization of HMGB1 in normal or LPS-activated cells was investigated by immunocytochemical analysis and HMGB1 released from cultured macrophages by Western blot. HSR was performed by incubating RAW 264.7 cells at 42.5 degrees C for 1 h then recovery at 37 degrees C for 12 h. The effect of HSR on expression and release of HMGB1 was observed. The results showed that a decrease of HMGB1 mRNA expression was observed at 18 h after LPS (500 ng/mL) treatment, although the total intracellular HMGB1 protein levels were not affected. A visible translocation of HMGB1 from the nuclear to the cytoplasm was observed at 20 h after stimulation with LPS (500 ng/mL). Furthermore, HMGB1 was released into the medium by LPS-activated RAW 264.7 cells in a time- and dose-dependent manner. Heat shock pretreatment significantly inhibited LPS-induced release of HMGB1 and the translocation of HMGB1 from the nucleus to the cytoplasm in RAW 264.7 cells. These findings suggest that the release of HMGB1 by LPS-activated macrophages is a late event in the pathogenesis of sepsis and that HSR could inhibit the release and translocation of HMGB1 induced by LPS.

Animals↗

PubMed2005

Heat shock pretreatment inhibited the release of Smac/DIABLO from mitochondria and apoptosis induced by hydrogen peroxide in cardiomyocytes and C2C12 myogenic cells.

Oxidative stress may cause apoptosis of cardiomyocytes in ischemia-reperfused myocardium, and heat shock pretreatment is thought to be protective against ischemic injury when cardiac myocytes are subjected to ischemia or simulated ischemia. However, the detailed mechanisms responsible for the protective effect of heat shock pretreatment are currently unclear. The aim of this study was to determine whether heat shock pretreatment exerts a protective effect against hydrogen peroxide(H2O2)-induced apoptotic cell death in neonatal rat cardiomyocytes and C2C12 myogenic cells and whether such protection is associated with decreased release of second mitochondria-derived activator of caspase-direct IAP binding protein with low pl (where IAP is inhibitor of apoptosis protein) (Smac/DIABLO) from mitochondria and the activation of caspase-9 and caspase-3. After heat shock pretreatment (42 +/- 0.3 degrees C for 1 hour, recovery for 12 hours), cardiomyocytes and C2C12 myogenic cells were exposed to H2O2 (0.5 mmol/L) for 6, 12, 24, and 36 hours. Apoptosis was evaluated by Hoechst 33258 staining and DNA laddering. Caspase-9 and caspase-3 activities were assayed by caspase colorimetric assay kit and Western analysis. Inducible heat shock proteins (Hsp) were detected using Western analysis. The release of Smac/DIABLO from mitochondria to cytoplasm was observed by Western blot and indirect immunofluorescence analysis. (1) H2O2 (0.5 mmol/L) exposure induced apoptosis in neonatal rat cardiomyocytes and C2C12 myogenic cells, with a marked release of Smac/DIABLO from mitochondria into cytoplasm and activation of caspase-9 and caspase-3, (2) heat shock pretreatment induced expression of Hsp70, Hsp90, and alphaB-crystallin and inhibited H2O2-mediated Smac/DIABLO release from mitochondria, the activation of caspase-9, caspase-3, and subsequent apoptosis. H2O2 can induce the release of Smac/DIABLO from mitochondria and apoptosis in cardiomyocytes and C2C12 myogenic cells. Heat shock pretreatment protects the cells against H2O2-induced apoptosis, and its mechanism appears to involve the inhibition of Smac release from mitochondria.

Animals↗