SOCS3 regulates p21 expression and cell cycle arrest in response to DNA damage

Genotoxic agents such as ionizing radiation trigger cell cycle arrest at the G1/S and G2/M checkpoints, allowing cells to repair damaged DNA before entry into mitosis. DNA damage-induced G1 arrest involves p53-dependent expression of p21 (Cip1/Waf-1), which inhibits cyclin-dependent kinases and blocks S phase entry. While much of the core DNA damage response has been well-studied, other signaling proteins that intersect with and modulate this response remain uncharacterized. In this study, we identify Suppressor of Cytokine Signaling (SOCS)-3 as an important regulator of radiation-induced G1 arrest. SOCS3-deficient fibroblasts fail to undergo G1 arrest and accumulate in the G2/M phase of the cell cycle. SOCS3 knockout cells phosphorylate p53 and H2AX normally in response to radiation, but fail to upregulate p21 expression. In addition, STAT3 phosphorylation is elevated in SOCS3-deficient cells compared to WT cells. Normal G1 arrest can be restored in SOCS3 KO cells by retroviral transduction of WT SOCS3 or a dominant-negative mutant of STAT3. Our results suggest a novel function for SOCS3 in the control of genome stability by negatively regulating STAT3-dependent radioresistant DNA synthesis, and promoting p53-dependent p21 expression.     

Removal of linear and branched alkylphenols from aqueous solutions with horseradish peroxidase

Alkylphenols were effectively treated with horseradish peroxidase at pH 7.0 and 30 degrees C in the presence of H(2)O(2) and poly(ethylene glycol) irrespective of the relative position or isomeric form of the alkyl chains. Water-insoluble oligomer precipitates were readily filtered out after enzymatic treatment, and transparent and colorless solutions were obtained for all p- and m-alkylphenols used.     

Synthesis of D-trigalacturonic acid methylglycoside and conformational comparison with its sulfur analogue

D-Trigalacturonic acid methylglycoside (3) was synthesized to evaluate the previously synthesized sulfur analogue 1 by comparison. The NOE experiments revealed that both 3 and 1 took on a similar conformation around their glycosyl linkage.     

Actin -related protein 3 (Arp3) is mutated in proteinuric BUF/Mna rats

The BUF/Mna strain of rat is a model of focal and segmental glomerulosclerosis (FSGS) in which a quantitative trait locus (QTL) for proteinuria, Pur1, has been identified. The aim of the present study was to identify candidates for the Pur1 gene. To narrow the Pur1 QTL, we performed fine QTL mapping and single nucleotide polymorphism (SNP) genotyping. To identify candidate genes, sequencing and gene-expression analyses of all genes contained in the narrowed locus were conducted. The narrowed Pur1 region contained 25 genes. Among these genes, only the Arp3 gene was mutated in the BUF/Mna strain; it contained a missense mutation that caused an ^L111^F substitution. This leucine is conserved across species. Gene-expression analysis failed to identify any other candidate genes for Pur1. Arp3-mediated actin assembly abnormalities were visible in immunohistochemical and electron microscopic examinations of podocytes in old BUF/Mna rats. Taken together, these data suggest that Arp3 is a candidate for the Pur1 gene. This observation is consistent with our growing recognition that abnormal signaling-induced assembly of actin in podocytes leads to the development of FSGS. Nucleotide sequence data reported in this article are available in the DDBJ/EMBL/GenBank database under accession numbers AB292042-292043 and AB294577-294580.     

A case of gastrointestinal stromal tumor with spontaneous rupture in the greater omentum

Background

Although GIST generally occurs in the digestive tract, such as the stomach, and small and small intestine primarily, Omental GIST tumours are very rare.

Case Presentation

A 63-year-old male patient, who recognized an abdominal tumor 1 year before admission, had a slight expansion of the tumor, reduction of the body and malaise, was consulted to our hospital. Abdominal CT and MRI revealed a cystic lesion of 26 cm in diameter with a clear boundary from immediately below the interseptum to the pelvic cavity, and imaged the septum and cystic wall. We considered that the patient had a cystic tumor in the abdomen, of which the primary lesion was unknown, and scheduled surgery. The patient unfortunately deteriorated with shock and sudden pain in the abdomen. Wediagnosed tumor rapture, and emergency surgery was performed. The tumor, weighing 3,600 g, was mostly cystic, and filled with sanguinous fluid and clot. Histologically, the tumor was composed of spindle cells, and was positive for c-KIT (CD117), slightly positive for alpha-smooth muscle actin (SMA), and S-100 protein positive. Based on these findings, the tumor was diagnosed as GIST primarily occurring in the greater omentum.

Conclusion

We experienced a rare case of GIST which originated from the greater omentum. Recently, the prognosis of GIST has been improved since the treatment with Imatinib.It is necessary to consider the diagnosis of GIST on encountering a mass in the greater omentum.

     

Genetic variation in rice

Completion of the genomic sequencing of rice has enhanced the discovery of new genes. Wild rice relatives are good sources for extending the genetic variation of cultivated rice. Reproductive barriers are commonly found in distant crosses of rice and are attracting attention. The combination of genetic analyses and molecular tools has greatly facilitated the molecular cloning of rice genes based on the classical approach and enabled the tracking of dissemination of the alleles for domestication. Basic information for population genetics study in rice is still being collected and is expected to provide an alternative approach for finding new genes. The wide genetic variation available in wild rice relatives and the combination of various genetic approaches will allow the analysis and understanding of genetic variation at the nucleotide sequence level, as well as the discovery of novel alleles by sequence-based approaches.     

Inhibition of Sudan I genotoxicity in human liver-derived HepG2 cells by the antioxidant hydroxytyrosol

The chemoprotective effect of hydroxytyrosol (HT) against Sudan I-induced genotoxicity was investigated in a human hepatoma cell line, HepG2. The comet assay and micronucleus (MN) assay were used to monitor genotoxicity. Intracellular reactive oxygen species (ROS) formation was measured using a fluorescent probe, 2,7-dichlorofluorescein diacetate (DCFH-DA). The levels of oxidative DNA damage and lipid peroxidation were estimated by immunocytochemistry analysis of 8-hydroxydeoxyguanosine (8-OHdG) and by measuring levels of thiobarbituric acid-reactive substances (TBARS), respectively. Intracellular glutathione (GSH) level was estimated by fluorometric methods. The results showed that HT significantly reduced the genotoxicity caused by Sudan I. Furthermore, HT ameliorated lipid pexidation as demonstrated by a reduction in TBARS formation and attenuated GSH depletion in a concentration-dependent manner. It was also found that HT reduced intracellular ROS formation and 8-OHdG level caused by Sudan I. These results strongly suggest that HT has significant protective ability against Sudan I-induced genotoxicity.     

Alteration of a recombinant protein <Emphasis Type="Italic">N</Emphasis>-glycan structure in silkworms by partial suppression of <Emphasis Type="Italic">N</Emphasis>-acetylglucosaminidase gene expression

Objective

To synthesize complex type N-glycans in silkworms, shRNAs against the fused lobe from Bombyx mori (BmFDL), which codes N-acetylglucosaminidase (GlcNAcase) in the Golgi, was expressed by recombinant B. mori nucleopolyhedrovirus (BmNPV) in silkworm larvae.

Results

Expression was under the control of the actin promoter of B. mori or the U6-2 and i.e.-2 promoters from Orgyia pseudotsugata multiple nucleopolyhedrovirus (OpMNPV). The reduction of specific GlcNAcase activity was observed in Bm5 cells and silkworm larvae using the U6-2 promoter. In silkworm larvae, the partial suppression of BmFDL gene expression was observed. When shRNA against BmFDL was expressed under the control of U6-2 promoter, the Man₃GlcNAc(Fuc)GlcNAc structure appeared in a main N-glycans of recombinant human IgG. These results suggested that the control of BmFDL expression by its shRNA in silkworms caused the modification of its N-glycan synthetic pathway, which may lead to the alteration of N-glycans in the expressed recombinant proteins.

Conclusions

Suppression of BmFDL gene expression by shRNA is not sufficient to synthesize complex N-glycans in silkworm larvae but can modify the N-glycan synthetic pathway.