Down-regulation of senescence marker protein 30 by iron-specific chelator deferoxamine drives cell senescence

To our knowledge, this is the first study to report down-regulation of senescence marker protein 30 (SMP30) by iron-specific chelator deferoxamine (DFO) on FAO cell senescence, using a DNA microarray. Furthermore, DFO treatment increased senescence marker β-galactosidase activity, whereas this activity was attenuated by overexpression of SMP30. Our data suggested that down-regulation of SMP30 drives cell senescence in iron-chelated condition.     

Filopodium-derived vesicles produced by MIM enhance the migration of recipient cells

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Campest-5-en-3-one,an oxidized derivative of campesterol,activates PPARα, promotes energy consumption and reduces visceral fat deposition in rats

Dietary campest-5-en-3-one (campestenone), an oxidized derivative of campesterol, significantly reduced visceral fat weight and the concentration of triacylglycerol in serum and liver of rats. Dietary campestenone dramatically increased the activities and the mRNA expressions of mitochondrial and peroxisomal enzymes involved in β-oxidation in the liver. Campestenone activated human peroxisome proliferator-activated receptor (PPAR) α as determined using the novel GAL4 ligand-binding domain chimera assay system with coactivator coexpression. In contrast, dietary campestenone reduced the activities and the mRNA expressions of enzymes involved in fatty acid synthesis, except for the malic enzyme. Dietary campestenone decreased the sterol regulatory element binding protein-1 (SREBP-1) mRNA level. Energy expenditure was significantly higher in the feeding of campestenone in rats. Dietary campestenone reduced hepatic cholesterol concentration and increased fecal excretion of neutral steroids originated from cholesterol. Lymphatic absorption of cholesterol was reduced by the coadministration of campestenone in rats cannulated in the thoracic duct. These observations suggest a possibility that campestenone has an ability to prevent coronary heart disease by improving obesity and abnormality of lipid metabolism.     

Thec-kit receptor transduces the stem cell factor-triggered growth signal in murine interleukin-3-dependent cell line

The stem cell factor is a glycoprotein hormone which regulates the proliferation and differentiation of primitive hematopoietic cells through its interaction with a tyrosine kinase transmembrane receptor which is encoded by thec-kit proto-oncogene. To examine whether a murinec-kit receptor can be functional in murine interleukin-3 (mlL-3)-dependent hematopoietic cell line, we introduced the murinec-kit cDNA into mlL-3-dependent pro-B cell line Ba/F3. One of the resulting clones, Ba/F3 clone BF-K96, expressed the 140 kDa protein recognized by anti-c-kit monoclonal antibody and the expressedc-kit receptor protein on the cell surface bound to a radiolabeled soluble form of murine stem cell factor (mSCF) with high affinity. BF-K96 clone expressing thec-kit receptor could proliferate in response to mSCF in the absence of mlL-3. The cell clone could also grow in co-culture with mouse 3T3 cells which are endogeneously expressing a membrane-associated type of mSCF on their cell surfaces. These findings demonstrate that thec-kit receptor expressed on mlL-3-dependent hematopoietic cell line Ba/F3 transduce the mSCF-dependent growth signal, indicating that established cell clone will provide a unique cellular system for the study of SCF/c-kit signal transduction mechanism.Abbreviations SCF stem cell factor - IL interleukin - CSF colony stimulating factor - IMDM Iscove's Modified Dulbecco's Medium - DME Dulbecco's Modified Eagle's Medium - FCS fetal calf serum - PCR polymerase chain reaction - EDTA ethylenediaminetetra-acetic acid; sodium dodecyl sulfate     

Metabolic engineering to improve 1,5-diaminopentane production from cellobiose using β-glucosidase-secreting Corynebacterium glutamicum

Microbial production of 1,5-diaminopentane (DAP) from renewable feedstock is a promising and sustainable approach for the production of polyamides. In this study, we constructed a β-glucosidase (BGL)-secreting Corynebacterium glutamicum and successfully used this strain to produce DAP from cellobiose and glucose. First, C. glutamicum was metabolically engineered to produce l -lysine (a direct precursor of DAP), followed by the coexpression of l -lysine decarboxylase and BGL derived from Escherichia coli and Thermobifida fusca YX (Tfu0937), respectively. This new engineered C. glutamicum strain produced 27 g/L of DAP from cellobiose in CGXII minimal medium using fed-batch cultivation. The yield of DAP was 0.43 g/g glucose (1 g of cellobiose corresponds to 1.1 g of glucose), which is the highest yield reported to date. These results demonstrate the feasibility of DAP production from cellobiose or cellooligosaccharides using an engineered C. glutamicum strain.     

The C-terminal domain of the toxic fragment of a Bacillus thuringiensis crystal protein determines receptor binding

The insecticidal crystal proteins of Bacillus thuringiensis show a high degree of specificity. In vitro binding studies with several crystal proteins demonstrated a correlation between toxicity and binding to receptors of larval midgut epithelial cells. In order to study the domain-function relationships of the toxic fragment, hybrid crystal proteins based on CryIA(b) and CryIC were constructed. Two out of 11 hybrid proteins constructed exhibited insecticidal activity. Both dispalyed an insecticidal spectrum similar to that of the parental crystal protein from which the C-terminal part of the toxic fragment originated. In addition, in vitro binding studies directly demonstrated the involvement of the C-terminal part of the toxic fragment in receptor binding. These results demonstrate that the C-terminal part of the toxic fragment determines specific receptor binding, which in turn determines, to a large extent, the insect specificity.