A nucleoside anticancer drug, 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)cytosine (TAS106), sensitizes cells to radiation by suppressing BRCA2 expression

<p>Abstract</p> <p>Background</p> <p>A novel anticancer drug 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)cytosine (ECyd, TAS106) has been shown to radiosensitize tumor cells and to improve the therapeutic efficiency of X-irradiation. However, the effect of TAS106 on cellular DNA repair capacity has not been elucidated. Our aim in this study was to examine whether TAS106 modified the repair capacity of DNA double-strand breaks (DSBs) in tumor cells.</p> <p>Methods</p> <p>Various cultured cell lines treated with TAS106 were irradiated and then survival fraction was examined by the clonogenic survival assays. Repair of sublethal damage (SLD), which indicates DSBs repair capacity, was measured as an increase of surviving cells after split dose irradiation with an interval of incubation. To assess the effect of TAS106 on the DSBs repair activity, the time courses of γ-H2AX and 53BP1 foci formation were examined by using immunocytochemistry. The expression of DNA-repair-related proteins was also examined by Western blot analysis and semi-quantitative RT-PCR analysis.</p> <p>Results</p> <p>In clonogenic survival assays, pretreatment of TAS106 showed radiosensitizing effects in various cell lines. TAS106 inhibited SLD repair and delayed the disappearance of γ-H2AX and 53BP1 foci, suggesting that DSB repair occurred in A549 cells. Western blot analysis demonstrated that TAS106 down-regulated the expression of BRCA2 and Rad51, which are known as keys among DNA repair proteins in the homologous recombination (HR) pathway. Although a significant radiosensitizing effect of TAS106 was observed in the parental V79 cells, pretreatment with TAS106 did not induce any radiosensitizing effects in BRCA2-deficient V-C8 cells.</p> <p>Conclusions</p> <p>Our results indicate that TAS106 induces the down-regulation of BRCA2 and the subsequent abrogation of the HR pathway, leading to a radiosensitizing effect. Therefore, this study suggests that inhibition of the HR pathway may be useful to improve the therapeutic efficiency of radiotherapy for solid tumors.</p

Motor-Coordination-Dependent Learning, More than Others, Is Impaired in Transgenic Mice Expressing Pseudorabies Virus Immediate-Early Protein IE180

The cerebellum in transgenic mice expressing pseudorabies virus immediate-early protein IE180 (TgIE96) was substantially diminished in size, and its histoarchitecture was severely disorganized, resulting in severe ataxia. TgIE96 mice can therefore be used as an experimental model to study the involvement of cerebellar circuits in different learning tasks. The performance of three-month-old TgIE96 mice was studied in various behavioral tests, including associative learning (classical eyeblink conditioning), object recognition, spatial orientation (water maze), startle response and prepulse inhibition, and passive avoidance, and compared with that of wild-type mice. Wild-type and TgIE96 mice presented similar reflexively evoked eyeblinks, and acquired classical conditioned eyelid responses with similar learning curves for both trace and delay conditioning paradigms. The two groups of mice also had similar performances during the object recognition test. However, they showed significant differences for the other three tests included in this study. Although both groups of animals were capable of swimming, TgIE96 mice failed to learn the water maze task during the allowed time. The startle response to a severe tone was similar in both control and TgIE96 mice, but the latter were unable to produce a significant prepulse inhibition. TgIE96 mice also presented evident deficits for the proper accomplishment of a passive avoidance test. These results suggest that the cerebellum is not indispensable for the performance of classical eyeblink conditioning and for object recognition tasks, but seems to be necessary for the proper performance of water maze, prepulse inhibition, and passive avoidance tests

Molecular epidemiology of avian influenza viruses circulating among healthy poultry flocks in farms in northern Vietnam.

Repeated epizootics of highly pathogenic avian influenza (HPAI) virus subtype H5N1 were reported from 2003 to 2005 among poultry in Vietnam. More than 200 million birds were killed to control the spread of the disease. Human cases of H5N1 infection have been sporadically reported in an area where repeated H5N1 outbreaks among birds had occurred. Subtype H5N1 strains are established as endemic among poultry in Vietnam, however, insights into how avian influenza viruses including the H5N1 subtype are maintained in endemic areas is not clear. In order to determine the prevalence of different avian influenza viruses (AIVs), including H5N1 circulating among poultry in northern Vietnam, surveillance was conducted during the years 2006-2009. A subtype H5N1 strain was isolated from an apparently healthy duck reared on a farm in northern Vietnam in 2008 and was identified as an HPAI. Although only one H5N1 virus was isolated, it supports the view that healthy domestic ducks play a pivotal role in maintaining and transmitting H5N1 viruses which cause disease outbreaks in northern Vietnam. In addition, a total of 26 AIVs with low pathogenicity were isolated from poultry and phylogenetic analysis of all the eight gene segments revealed their diverse genetical backgrounds, implying that reassortments have occurred frequently among strains in northern Vietnam. It is, therefore, important to monitor the prevalence of influenza viruses among healthy poultry between epidemics in an area where AIVs are endemic

Functional analysis of duck, goose, and ostrich 2 '-5 '-oligoadenylate synthetase

Up-to-date the flavivirus infection in avian taxa is not clearly defined. Several reports have demonstrated that many viruses belonging to Flaviviridae may cause diseases in poultry species; however, the susceptibility of other avian species is variable and still unclear. In human and mice, the 2'-5'-oligoadenylate synthetase (OAS) proteins are associated with resistance to the flavivirus infection as well as other virus infections. However, the avian OAS proteins are rarely studied. In our previous studies, we confirmed that the chicken OAS-like protein (chOASL) expressed OAS-enzymatic activity (the classical OAS/RNase L-dependent pathway) as well as the anti-flavivirus activity (the putative OAS/RNase L-independent pathway). Therefore, the current study aimed at functional analysis of avian OAS proteins from duck, goose, and ostrich. The duOASL, goOASL, and osOAS1 proteins expressed enzymatic activity as well as chOASL, whereas osOASL expressed little enzymatic activity. On the other hand, duOASL, goOASL, and osOASL possessed significant antiviral activity against West Nile virus (WNV)-replicon replication as well as chOASL, whereas osOAS1 did not. In addition, similar to chOASL, their antiviral activity was independent of RNase L activation. These results suggest that OASL is the only OAS protein in the duck and goose as well as chicken and possesses both OAS-enzymatic and anti-flavivirus activities, whereas the ostrich possesses both OAS1 and OASL proteins with sharing the functional activities, OAS-enzymatic and anti-flavivirus activities, respectively. It is of interest that the ostrich undergoes differential process in OAS gene evolution from other poultries and thus possesses different molecular mechanism in antiviral activity

Nfkbiz regulates the proliferation and differentiation of keratinocytes

Nuclear factor of kappa light polypeptide gene enhancer in B cells (NF-κB) inhibitor zeta (Nfkbiz) is a nuclear inhibitor of NF-κB (IκB) protein that is also termed as molecule possessing ankyrin repeats induced by lipopolysaccharide, interleukin-1-inducible nuclear ankyrin repeat protein, or IκBζ. We found previously that disrupting the Nfkbiz gene resulted in atopic dermatitis-like lesions in mice, suggesting an important role for Nfkbiz in the skin. In this study, we examined the cellular function of Nfkbiz in keratinocytes. Immunohistochemical analyses for Ki-67 revealed that Nfkbiz－/－ keratinocytes were hypoproliferative. In skin from Nfkbiz－/－ mice, the expression of the keratinocyte differentiation markers K10 and filaggrin were reduced, although that of K14 was unchanged. The terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay revealed that the frequency of apoptosis was comparable between control and Nfkbiz－/－ keratinocytes. Interestingly, the subcellular localization of the NF-κB subunits and the transcriptional activity of NF-κB were not changed in Nfkbiz－/－ keratinocytes. These findings indicate a novel possible role of Nfkbiz in controlling the proliferation and differentiation of epidermal keratinocytes through NF-κB-independent mechanisms

HYPERPLASIA OF BROWN ADIPOSE TISSUE AFTER CHRONIC STIMULATION OF β3-ADRENERGIC RECEPTOR IN RATS

When mammals are exposed to a cold environment for a long time, the capacity of nonshivering thermogenesis by brown adipose tissue (BAT) increases in association with the increased expression of some specific proteins and tissue hyperplasia, which are totally dependent on sympathetic innervation to this tissue. To clarify roles of the β-adrenergic mechanism in BAT hyperplasia, the effects of chronic administration of various β-adrenergic agonists on BAT were examined in rats, especially focusing on some agonists to the β3-adrenoceptor which is present specifically in adipocytes. Chronic administration of noradrenaline or isoproterenol for 7-10 days produced a marked increase in the tissue contents of DNA, total protein, mitochondrial uncoupling protein, and insulinregulatable glucose transporter protein. The trophic effects of noradrenaline and isoproterenol were mimicked by chronic administration of β3-adrenergic agonists, such as CL316,243,BRL 26830A, and ICI D7114. These results suggest that the β3-adrenoceptor plays important roles for hyperplasia of BAT, and thereby increasing in the capacity of thermogenesis